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1/*
2 * linux/fs/exec.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7/*
8 * #!-checking implemented by tytso.
9 */
10/*
11 * Demand-loading implemented 01.12.91 - no need to read anything but
12 * the header into memory. The inode of the executable is put into
13 * "current->executable", and page faults do the actual loading. Clean.
14 *
15 * Once more I can proudly say that linux stood up to being changed: it
16 * was less than 2 hours work to get demand-loading completely implemented.
17 *
18 * Demand loading changed July 1993 by Eric Youngdale. Use mmap instead,
19 * current->executable is only used by the procfs. This allows a dispatch
20 * table to check for several different types of binary formats. We keep
21 * trying until we recognize the file or we run out of supported binary
22 * formats.
23 */
24
25#include <linux/slab.h>
26#include <linux/file.h>
27#include <linux/fdtable.h>
28#include <linux/mm.h>
29#include <linux/vmacache.h>
30#include <linux/stat.h>
31#include <linux/fcntl.h>
32#include <linux/swap.h>
33#include <linux/string.h>
34#include <linux/init.h>
35#include <linux/pagemap.h>
36#include <linux/perf_event.h>
37#include <linux/highmem.h>
38#include <linux/spinlock.h>
39#include <linux/key.h>
40#include <linux/personality.h>
41#include <linux/binfmts.h>
42#include <linux/utsname.h>
43#include <linux/pid_namespace.h>
44#include <linux/module.h>
45#include <linux/namei.h>
46#include <linux/mount.h>
47#include <linux/security.h>
48#include <linux/syscalls.h>
49#include <linux/tsacct_kern.h>
50#include <linux/cn_proc.h>
51#include <linux/audit.h>
52#include <linux/tracehook.h>
53#include <linux/kmod.h>
54#include <linux/fsnotify.h>
55#include <linux/fs_struct.h>
56#include <linux/pipe_fs_i.h>
57#include <linux/oom.h>
58#include <linux/compat.h>
59#include <linux/vmalloc.h>
60
61#include <asm/uaccess.h>
62#include <asm/mmu_context.h>
63#include <asm/tlb.h>
64
65#include <trace/events/task.h>
66#include "internal.h"
67
68#include <trace/events/sched.h>
69
70int suid_dumpable = 0;
71
72static LIST_HEAD(formats);
73static DEFINE_RWLOCK(binfmt_lock);
74
75void __register_binfmt(struct linux_binfmt * fmt, int insert)
76{
77 BUG_ON(!fmt);
78 if (WARN_ON(!fmt->load_binary))
79 return;
80 write_lock(&binfmt_lock);
81 insert ? list_add(&fmt->lh, &formats) :
82 list_add_tail(&fmt->lh, &formats);
83 write_unlock(&binfmt_lock);
84}
85
86EXPORT_SYMBOL(__register_binfmt);
87
88void unregister_binfmt(struct linux_binfmt * fmt)
89{
90 write_lock(&binfmt_lock);
91 list_del(&fmt->lh);
92 write_unlock(&binfmt_lock);
93}
94
95EXPORT_SYMBOL(unregister_binfmt);
96
97static inline void put_binfmt(struct linux_binfmt * fmt)
98{
99 module_put(fmt->module);
100}
101
102bool path_noexec(const struct path *path)
103{
104 return (path->mnt->mnt_flags & MNT_NOEXEC) ||
105 (path->mnt->mnt_sb->s_iflags & SB_I_NOEXEC);
106}
107
108#ifdef CONFIG_USELIB
109/*
110 * Note that a shared library must be both readable and executable due to
111 * security reasons.
112 *
113 * Also note that we take the address to load from from the file itself.
114 */
115SYSCALL_DEFINE1(uselib, const char __user *, library)
116{
117 struct linux_binfmt *fmt;
118 struct file *file;
119 struct filename *tmp = getname(library);
120 int error = PTR_ERR(tmp);
121 static const struct open_flags uselib_flags = {
122 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
123 .acc_mode = MAY_READ | MAY_EXEC,
124 .intent = LOOKUP_OPEN,
125 .lookup_flags = LOOKUP_FOLLOW,
126 };
127
128 if (IS_ERR(tmp))
129 goto out;
130
131 file = do_filp_open(AT_FDCWD, tmp, &uselib_flags);
132 putname(tmp);
133 error = PTR_ERR(file);
134 if (IS_ERR(file))
135 goto out;
136
137 error = -EINVAL;
138 if (!S_ISREG(file_inode(file)->i_mode))
139 goto exit;
140
141 error = -EACCES;
142 if (path_noexec(&file->f_path))
143 goto exit;
144
145 fsnotify_open(file);
146
147 error = -ENOEXEC;
148
149 read_lock(&binfmt_lock);
150 list_for_each_entry(fmt, &formats, lh) {
151 if (!fmt->load_shlib)
152 continue;
153 if (!try_module_get(fmt->module))
154 continue;
155 read_unlock(&binfmt_lock);
156 error = fmt->load_shlib(file);
157 read_lock(&binfmt_lock);
158 put_binfmt(fmt);
159 if (error != -ENOEXEC)
160 break;
161 }
162 read_unlock(&binfmt_lock);
163exit:
164 fput(file);
165out:
166 return error;
167}
168#endif /* #ifdef CONFIG_USELIB */
169
170#ifdef CONFIG_MMU
171/*
172 * The nascent bprm->mm is not visible until exec_mmap() but it can
173 * use a lot of memory, account these pages in current->mm temporary
174 * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
175 * change the counter back via acct_arg_size(0).
176 */
177static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
178{
179 struct mm_struct *mm = current->mm;
180 long diff = (long)(pages - bprm->vma_pages);
181
182 if (!mm || !diff)
183 return;
184
185 bprm->vma_pages = pages;
186 add_mm_counter(mm, MM_ANONPAGES, diff);
187}
188
189static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
190 int write)
191{
192 struct page *page;
193 int ret;
194
195#ifdef CONFIG_STACK_GROWSUP
196 if (write) {
197 ret = expand_downwards(bprm->vma, pos);
198 if (ret < 0)
199 return NULL;
200 }
201#endif
202 /*
203 * We are doing an exec(). 'current' is the process
204 * doing the exec and bprm->mm is the new process's mm.
205 */
206 ret = get_user_pages_remote(current, bprm->mm, pos, 1, write,
207 1, &page, NULL);
208 if (ret <= 0)
209 return NULL;
210
211 if (write) {
212 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
213 struct rlimit *rlim;
214
215 acct_arg_size(bprm, size / PAGE_SIZE);
216
217 /*
218 * We've historically supported up to 32 pages (ARG_MAX)
219 * of argument strings even with small stacks
220 */
221 if (size <= ARG_MAX)
222 return page;
223
224 /*
225 * Limit to 1/4-th the stack size for the argv+env strings.
226 * This ensures that:
227 * - the remaining binfmt code will not run out of stack space,
228 * - the program will have a reasonable amount of stack left
229 * to work from.
230 */
231 rlim = current->signal->rlim;
232 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
233 put_page(page);
234 return NULL;
235 }
236 }
237
238 return page;
239}
240
241static void put_arg_page(struct page *page)
242{
243 put_page(page);
244}
245
246static void free_arg_page(struct linux_binprm *bprm, int i)
247{
248}
249
250static void free_arg_pages(struct linux_binprm *bprm)
251{
252}
253
254static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
255 struct page *page)
256{
257 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
258}
259
260static int __bprm_mm_init(struct linux_binprm *bprm)
261{
262 int err;
263 struct vm_area_struct *vma = NULL;
264 struct mm_struct *mm = bprm->mm;
265
266 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
267 if (!vma)
268 return -ENOMEM;
269
270 down_write(&mm->mmap_sem);
271 vma->vm_mm = mm;
272
273 /*
274 * Place the stack at the largest stack address the architecture
275 * supports. Later, we'll move this to an appropriate place. We don't
276 * use STACK_TOP because that can depend on attributes which aren't
277 * configured yet.
278 */
279 BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
280 vma->vm_end = STACK_TOP_MAX;
281 vma->vm_start = vma->vm_end - PAGE_SIZE;
282 vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
283 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
284 INIT_LIST_HEAD(&vma->anon_vma_chain);
285
286 err = insert_vm_struct(mm, vma);
287 if (err)
288 goto err;
289
290 mm->stack_vm = mm->total_vm = 1;
291 arch_bprm_mm_init(mm, vma);
292 up_write(&mm->mmap_sem);
293 bprm->p = vma->vm_end - sizeof(void *);
294 return 0;
295err:
296 up_write(&mm->mmap_sem);
297 bprm->vma = NULL;
298 kmem_cache_free(vm_area_cachep, vma);
299 return err;
300}
301
302static bool valid_arg_len(struct linux_binprm *bprm, long len)
303{
304 return len <= MAX_ARG_STRLEN;
305}
306
307#else
308
309static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
310{
311}
312
313static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
314 int write)
315{
316 struct page *page;
317
318 page = bprm->page[pos / PAGE_SIZE];
319 if (!page && write) {
320 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
321 if (!page)
322 return NULL;
323 bprm->page[pos / PAGE_SIZE] = page;
324 }
325
326 return page;
327}
328
329static void put_arg_page(struct page *page)
330{
331}
332
333static void free_arg_page(struct linux_binprm *bprm, int i)
334{
335 if (bprm->page[i]) {
336 __free_page(bprm->page[i]);
337 bprm->page[i] = NULL;
338 }
339}
340
341static void free_arg_pages(struct linux_binprm *bprm)
342{
343 int i;
344
345 for (i = 0; i < MAX_ARG_PAGES; i++)
346 free_arg_page(bprm, i);
347}
348
349static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
350 struct page *page)
351{
352}
353
354static int __bprm_mm_init(struct linux_binprm *bprm)
355{
356 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
357 return 0;
358}
359
360static bool valid_arg_len(struct linux_binprm *bprm, long len)
361{
362 return len <= bprm->p;
363}
364
365#endif /* CONFIG_MMU */
366
367/*
368 * Create a new mm_struct and populate it with a temporary stack
369 * vm_area_struct. We don't have enough context at this point to set the stack
370 * flags, permissions, and offset, so we use temporary values. We'll update
371 * them later in setup_arg_pages().
372 */
373static int bprm_mm_init(struct linux_binprm *bprm)
374{
375 int err;
376 struct mm_struct *mm = NULL;
377
378 bprm->mm = mm = mm_alloc();
379 err = -ENOMEM;
380 if (!mm)
381 goto err;
382
383 err = __bprm_mm_init(bprm);
384 if (err)
385 goto err;
386
387 return 0;
388
389err:
390 if (mm) {
391 bprm->mm = NULL;
392 mmdrop(mm);
393 }
394
395 return err;
396}
397
398struct user_arg_ptr {
399#ifdef CONFIG_COMPAT
400 bool is_compat;
401#endif
402 union {
403 const char __user *const __user *native;
404#ifdef CONFIG_COMPAT
405 const compat_uptr_t __user *compat;
406#endif
407 } ptr;
408};
409
410static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
411{
412 const char __user *native;
413
414#ifdef CONFIG_COMPAT
415 if (unlikely(argv.is_compat)) {
416 compat_uptr_t compat;
417
418 if (get_user(compat, argv.ptr.compat + nr))
419 return ERR_PTR(-EFAULT);
420
421 return compat_ptr(compat);
422 }
423#endif
424
425 if (get_user(native, argv.ptr.native + nr))
426 return ERR_PTR(-EFAULT);
427
428 return native;
429}
430
431/*
432 * count() counts the number of strings in array ARGV.
433 */
434static int count(struct user_arg_ptr argv, int max)
435{
436 int i = 0;
437
438 if (argv.ptr.native != NULL) {
439 for (;;) {
440 const char __user *p = get_user_arg_ptr(argv, i);
441
442 if (!p)
443 break;
444
445 if (IS_ERR(p))
446 return -EFAULT;
447
448 if (i >= max)
449 return -E2BIG;
450 ++i;
451
452 if (fatal_signal_pending(current))
453 return -ERESTARTNOHAND;
454 cond_resched();
455 }
456 }
457 return i;
458}
459
460/*
461 * 'copy_strings()' copies argument/environment strings from the old
462 * processes's memory to the new process's stack. The call to get_user_pages()
463 * ensures the destination page is created and not swapped out.
464 */
465static int copy_strings(int argc, struct user_arg_ptr argv,
466 struct linux_binprm *bprm)
467{
468 struct page *kmapped_page = NULL;
469 char *kaddr = NULL;
470 unsigned long kpos = 0;
471 int ret;
472
473 while (argc-- > 0) {
474 const char __user *str;
475 int len;
476 unsigned long pos;
477
478 ret = -EFAULT;
479 str = get_user_arg_ptr(argv, argc);
480 if (IS_ERR(str))
481 goto out;
482
483 len = strnlen_user(str, MAX_ARG_STRLEN);
484 if (!len)
485 goto out;
486
487 ret = -E2BIG;
488 if (!valid_arg_len(bprm, len))
489 goto out;
490
491 /* We're going to work our way backwords. */
492 pos = bprm->p;
493 str += len;
494 bprm->p -= len;
495
496 while (len > 0) {
497 int offset, bytes_to_copy;
498
499 if (fatal_signal_pending(current)) {
500 ret = -ERESTARTNOHAND;
501 goto out;
502 }
503 cond_resched();
504
505 offset = pos % PAGE_SIZE;
506 if (offset == 0)
507 offset = PAGE_SIZE;
508
509 bytes_to_copy = offset;
510 if (bytes_to_copy > len)
511 bytes_to_copy = len;
512
513 offset -= bytes_to_copy;
514 pos -= bytes_to_copy;
515 str -= bytes_to_copy;
516 len -= bytes_to_copy;
517
518 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
519 struct page *page;
520
521 page = get_arg_page(bprm, pos, 1);
522 if (!page) {
523 ret = -E2BIG;
524 goto out;
525 }
526
527 if (kmapped_page) {
528 flush_kernel_dcache_page(kmapped_page);
529 kunmap(kmapped_page);
530 put_arg_page(kmapped_page);
531 }
532 kmapped_page = page;
533 kaddr = kmap(kmapped_page);
534 kpos = pos & PAGE_MASK;
535 flush_arg_page(bprm, kpos, kmapped_page);
536 }
537 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
538 ret = -EFAULT;
539 goto out;
540 }
541 }
542 }
543 ret = 0;
544out:
545 if (kmapped_page) {
546 flush_kernel_dcache_page(kmapped_page);
547 kunmap(kmapped_page);
548 put_arg_page(kmapped_page);
549 }
550 return ret;
551}
552
553/*
554 * Like copy_strings, but get argv and its values from kernel memory.
555 */
556int copy_strings_kernel(int argc, const char *const *__argv,
557 struct linux_binprm *bprm)
558{
559 int r;
560 mm_segment_t oldfs = get_fs();
561 struct user_arg_ptr argv = {
562 .ptr.native = (const char __user *const __user *)__argv,
563 };
564
565 set_fs(KERNEL_DS);
566 r = copy_strings(argc, argv, bprm);
567 set_fs(oldfs);
568
569 return r;
570}
571EXPORT_SYMBOL(copy_strings_kernel);
572
573#ifdef CONFIG_MMU
574
575/*
576 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
577 * the binfmt code determines where the new stack should reside, we shift it to
578 * its final location. The process proceeds as follows:
579 *
580 * 1) Use shift to calculate the new vma endpoints.
581 * 2) Extend vma to cover both the old and new ranges. This ensures the
582 * arguments passed to subsequent functions are consistent.
583 * 3) Move vma's page tables to the new range.
584 * 4) Free up any cleared pgd range.
585 * 5) Shrink the vma to cover only the new range.
586 */
587static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
588{
589 struct mm_struct *mm = vma->vm_mm;
590 unsigned long old_start = vma->vm_start;
591 unsigned long old_end = vma->vm_end;
592 unsigned long length = old_end - old_start;
593 unsigned long new_start = old_start - shift;
594 unsigned long new_end = old_end - shift;
595 struct mmu_gather tlb;
596
597 BUG_ON(new_start > new_end);
598
599 /*
600 * ensure there are no vmas between where we want to go
601 * and where we are
602 */
603 if (vma != find_vma(mm, new_start))
604 return -EFAULT;
605
606 /*
607 * cover the whole range: [new_start, old_end)
608 */
609 if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
610 return -ENOMEM;
611
612 /*
613 * move the page tables downwards, on failure we rely on
614 * process cleanup to remove whatever mess we made.
615 */
616 if (length != move_page_tables(vma, old_start,
617 vma, new_start, length, false))
618 return -ENOMEM;
619
620 lru_add_drain();
621 tlb_gather_mmu(&tlb, mm, old_start, old_end);
622 if (new_end > old_start) {
623 /*
624 * when the old and new regions overlap clear from new_end.
625 */
626 free_pgd_range(&tlb, new_end, old_end, new_end,
627 vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
628 } else {
629 /*
630 * otherwise, clean from old_start; this is done to not touch
631 * the address space in [new_end, old_start) some architectures
632 * have constraints on va-space that make this illegal (IA64) -
633 * for the others its just a little faster.
634 */
635 free_pgd_range(&tlb, old_start, old_end, new_end,
636 vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
637 }
638 tlb_finish_mmu(&tlb, old_start, old_end);
639
640 /*
641 * Shrink the vma to just the new range. Always succeeds.
642 */
643 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
644
645 return 0;
646}
647
648/*
649 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
650 * the stack is optionally relocated, and some extra space is added.
651 */
652int setup_arg_pages(struct linux_binprm *bprm,
653 unsigned long stack_top,
654 int executable_stack)
655{
656 unsigned long ret;
657 unsigned long stack_shift;
658 struct mm_struct *mm = current->mm;
659 struct vm_area_struct *vma = bprm->vma;
660 struct vm_area_struct *prev = NULL;
661 unsigned long vm_flags;
662 unsigned long stack_base;
663 unsigned long stack_size;
664 unsigned long stack_expand;
665 unsigned long rlim_stack;
666
667#ifdef CONFIG_STACK_GROWSUP
668 /* Limit stack size */
669 stack_base = rlimit_max(RLIMIT_STACK);
670 if (stack_base > STACK_SIZE_MAX)
671 stack_base = STACK_SIZE_MAX;
672
673 /* Add space for stack randomization. */
674 stack_base += (STACK_RND_MASK << PAGE_SHIFT);
675
676 /* Make sure we didn't let the argument array grow too large. */
677 if (vma->vm_end - vma->vm_start > stack_base)
678 return -ENOMEM;
679
680 stack_base = PAGE_ALIGN(stack_top - stack_base);
681
682 stack_shift = vma->vm_start - stack_base;
683 mm->arg_start = bprm->p - stack_shift;
684 bprm->p = vma->vm_end - stack_shift;
685#else
686 stack_top = arch_align_stack(stack_top);
687 stack_top = PAGE_ALIGN(stack_top);
688
689 if (unlikely(stack_top < mmap_min_addr) ||
690 unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
691 return -ENOMEM;
692
693 stack_shift = vma->vm_end - stack_top;
694
695 bprm->p -= stack_shift;
696 mm->arg_start = bprm->p;
697#endif
698
699 if (bprm->loader)
700 bprm->loader -= stack_shift;
701 bprm->exec -= stack_shift;
702
703 down_write(&mm->mmap_sem);
704 vm_flags = VM_STACK_FLAGS;
705
706 /*
707 * Adjust stack execute permissions; explicitly enable for
708 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
709 * (arch default) otherwise.
710 */
711 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
712 vm_flags |= VM_EXEC;
713 else if (executable_stack == EXSTACK_DISABLE_X)
714 vm_flags &= ~VM_EXEC;
715 vm_flags |= mm->def_flags;
716 vm_flags |= VM_STACK_INCOMPLETE_SETUP;
717
718 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
719 vm_flags);
720 if (ret)
721 goto out_unlock;
722 BUG_ON(prev != vma);
723
724 /* Move stack pages down in memory. */
725 if (stack_shift) {
726 ret = shift_arg_pages(vma, stack_shift);
727 if (ret)
728 goto out_unlock;
729 }
730
731 /* mprotect_fixup is overkill to remove the temporary stack flags */
732 vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
733
734 stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
735 stack_size = vma->vm_end - vma->vm_start;
736 /*
737 * Align this down to a page boundary as expand_stack
738 * will align it up.
739 */
740 rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
741#ifdef CONFIG_STACK_GROWSUP
742 if (stack_size + stack_expand > rlim_stack)
743 stack_base = vma->vm_start + rlim_stack;
744 else
745 stack_base = vma->vm_end + stack_expand;
746#else
747 if (stack_size + stack_expand > rlim_stack)
748 stack_base = vma->vm_end - rlim_stack;
749 else
750 stack_base = vma->vm_start - stack_expand;
751#endif
752 current->mm->start_stack = bprm->p;
753 ret = expand_stack(vma, stack_base);
754 if (ret)
755 ret = -EFAULT;
756
757out_unlock:
758 up_write(&mm->mmap_sem);
759 return ret;
760}
761EXPORT_SYMBOL(setup_arg_pages);
762
763#endif /* CONFIG_MMU */
764
765static struct file *do_open_execat(int fd, struct filename *name, int flags)
766{
767 struct file *file;
768 int err;
769 struct open_flags open_exec_flags = {
770 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
771 .acc_mode = MAY_EXEC,
772 .intent = LOOKUP_OPEN,
773 .lookup_flags = LOOKUP_FOLLOW,
774 };
775
776 if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
777 return ERR_PTR(-EINVAL);
778 if (flags & AT_SYMLINK_NOFOLLOW)
779 open_exec_flags.lookup_flags &= ~LOOKUP_FOLLOW;
780 if (flags & AT_EMPTY_PATH)
781 open_exec_flags.lookup_flags |= LOOKUP_EMPTY;
782
783 file = do_filp_open(fd, name, &open_exec_flags);
784 if (IS_ERR(file))
785 goto out;
786
787 err = -EACCES;
788 if (!S_ISREG(file_inode(file)->i_mode))
789 goto exit;
790
791 if (path_noexec(&file->f_path))
792 goto exit;
793
794 err = deny_write_access(file);
795 if (err)
796 goto exit;
797
798 if (name->name[0] != '\0')
799 fsnotify_open(file);
800
801out:
802 return file;
803
804exit:
805 fput(file);
806 return ERR_PTR(err);
807}
808
809struct file *open_exec(const char *name)
810{
811 struct filename *filename = getname_kernel(name);
812 struct file *f = ERR_CAST(filename);
813
814 if (!IS_ERR(filename)) {
815 f = do_open_execat(AT_FDCWD, filename, 0);
816 putname(filename);
817 }
818 return f;
819}
820EXPORT_SYMBOL(open_exec);
821
822int kernel_read(struct file *file, loff_t offset,
823 char *addr, unsigned long count)
824{
825 mm_segment_t old_fs;
826 loff_t pos = offset;
827 int result;
828
829 old_fs = get_fs();
830 set_fs(get_ds());
831 /* The cast to a user pointer is valid due to the set_fs() */
832 result = vfs_read(file, (void __user *)addr, count, &pos);
833 set_fs(old_fs);
834 return result;
835}
836
837EXPORT_SYMBOL(kernel_read);
838
839int kernel_read_file(struct file *file, void **buf, loff_t *size,
840 loff_t max_size, enum kernel_read_file_id id)
841{
842 loff_t i_size, pos;
843 ssize_t bytes = 0;
844 int ret;
845
846 if (!S_ISREG(file_inode(file)->i_mode) || max_size < 0)
847 return -EINVAL;
848
849 ret = security_kernel_read_file(file, id);
850 if (ret)
851 return ret;
852
853 i_size = i_size_read(file_inode(file));
854 if (max_size > 0 && i_size > max_size)
855 return -EFBIG;
856 if (i_size <= 0)
857 return -EINVAL;
858
859 *buf = vmalloc(i_size);
860 if (!*buf)
861 return -ENOMEM;
862
863 pos = 0;
864 while (pos < i_size) {
865 bytes = kernel_read(file, pos, (char *)(*buf) + pos,
866 i_size - pos);
867 if (bytes < 0) {
868 ret = bytes;
869 goto out;
870 }
871
872 if (bytes == 0)
873 break;
874 pos += bytes;
875 }
876
877 if (pos != i_size) {
878 ret = -EIO;
879 goto out;
880 }
881
882 ret = security_kernel_post_read_file(file, *buf, i_size, id);
883 if (!ret)
884 *size = pos;
885
886out:
887 if (ret < 0) {
888 vfree(*buf);
889 *buf = NULL;
890 }
891 return ret;
892}
893EXPORT_SYMBOL_GPL(kernel_read_file);
894
895int kernel_read_file_from_path(char *path, void **buf, loff_t *size,
896 loff_t max_size, enum kernel_read_file_id id)
897{
898 struct file *file;
899 int ret;
900
901 if (!path || !*path)
902 return -EINVAL;
903
904 file = filp_open(path, O_RDONLY, 0);
905 if (IS_ERR(file))
906 return PTR_ERR(file);
907
908 ret = kernel_read_file(file, buf, size, max_size, id);
909 fput(file);
910 return ret;
911}
912EXPORT_SYMBOL_GPL(kernel_read_file_from_path);
913
914int kernel_read_file_from_fd(int fd, void **buf, loff_t *size, loff_t max_size,
915 enum kernel_read_file_id id)
916{
917 struct fd f = fdget(fd);
918 int ret = -EBADF;
919
920 if (!f.file)
921 goto out;
922
923 ret = kernel_read_file(f.file, buf, size, max_size, id);
924out:
925 fdput(f);
926 return ret;
927}
928EXPORT_SYMBOL_GPL(kernel_read_file_from_fd);
929
930ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
931{
932 ssize_t res = vfs_read(file, (void __user *)addr, len, &pos);
933 if (res > 0)
934 flush_icache_range(addr, addr + len);
935 return res;
936}
937EXPORT_SYMBOL(read_code);
938
939static int exec_mmap(struct mm_struct *mm)
940{
941 struct task_struct *tsk;
942 struct mm_struct *old_mm, *active_mm;
943
944 /* Notify parent that we're no longer interested in the old VM */
945 tsk = current;
946 old_mm = current->mm;
947 mm_release(tsk, old_mm);
948
949 if (old_mm) {
950 sync_mm_rss(old_mm);
951 /*
952 * Make sure that if there is a core dump in progress
953 * for the old mm, we get out and die instead of going
954 * through with the exec. We must hold mmap_sem around
955 * checking core_state and changing tsk->mm.
956 */
957 down_read(&old_mm->mmap_sem);
958 if (unlikely(old_mm->core_state)) {
959 up_read(&old_mm->mmap_sem);
960 return -EINTR;
961 }
962 }
963 task_lock(tsk);
964 active_mm = tsk->active_mm;
965 tsk->mm = mm;
966 tsk->active_mm = mm;
967 activate_mm(active_mm, mm);
968 tsk->mm->vmacache_seqnum = 0;
969 vmacache_flush(tsk);
970 task_unlock(tsk);
971 if (old_mm) {
972 up_read(&old_mm->mmap_sem);
973 BUG_ON(active_mm != old_mm);
974 setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
975 mm_update_next_owner(old_mm);
976 mmput(old_mm);
977 return 0;
978 }
979 mmdrop(active_mm);
980 return 0;
981}
982
983/*
984 * This function makes sure the current process has its own signal table,
985 * so that flush_signal_handlers can later reset the handlers without
986 * disturbing other processes. (Other processes might share the signal
987 * table via the CLONE_SIGHAND option to clone().)
988 */
989static int de_thread(struct task_struct *tsk)
990{
991 struct signal_struct *sig = tsk->signal;
992 struct sighand_struct *oldsighand = tsk->sighand;
993 spinlock_t *lock = &oldsighand->siglock;
994
995 if (thread_group_empty(tsk))
996 goto no_thread_group;
997
998 /*
999 * Kill all other threads in the thread group.
1000 */
1001 spin_lock_irq(lock);
1002 if (signal_group_exit(sig)) {
1003 /*
1004 * Another group action in progress, just
1005 * return so that the signal is processed.
1006 */
1007 spin_unlock_irq(lock);
1008 return -EAGAIN;
1009 }
1010
1011 sig->group_exit_task = tsk;
1012 sig->notify_count = zap_other_threads(tsk);
1013 if (!thread_group_leader(tsk))
1014 sig->notify_count--;
1015
1016 while (sig->notify_count) {
1017 __set_current_state(TASK_KILLABLE);
1018 spin_unlock_irq(lock);
1019 schedule();
1020 if (unlikely(__fatal_signal_pending(tsk)))
1021 goto killed;
1022 spin_lock_irq(lock);
1023 }
1024 spin_unlock_irq(lock);
1025
1026 /*
1027 * At this point all other threads have exited, all we have to
1028 * do is to wait for the thread group leader to become inactive,
1029 * and to assume its PID:
1030 */
1031 if (!thread_group_leader(tsk)) {
1032 struct task_struct *leader = tsk->group_leader;
1033
1034 for (;;) {
1035 threadgroup_change_begin(tsk);
1036 write_lock_irq(&tasklist_lock);
1037 /*
1038 * Do this under tasklist_lock to ensure that
1039 * exit_notify() can't miss ->group_exit_task
1040 */
1041 sig->notify_count = -1;
1042 if (likely(leader->exit_state))
1043 break;
1044 __set_current_state(TASK_KILLABLE);
1045 write_unlock_irq(&tasklist_lock);
1046 threadgroup_change_end(tsk);
1047 schedule();
1048 if (unlikely(__fatal_signal_pending(tsk)))
1049 goto killed;
1050 }
1051
1052 /*
1053 * The only record we have of the real-time age of a
1054 * process, regardless of execs it's done, is start_time.
1055 * All the past CPU time is accumulated in signal_struct
1056 * from sister threads now dead. But in this non-leader
1057 * exec, nothing survives from the original leader thread,
1058 * whose birth marks the true age of this process now.
1059 * When we take on its identity by switching to its PID, we
1060 * also take its birthdate (always earlier than our own).
1061 */
1062 tsk->start_time = leader->start_time;
1063 tsk->real_start_time = leader->real_start_time;
1064
1065 BUG_ON(!same_thread_group(leader, tsk));
1066 BUG_ON(has_group_leader_pid(tsk));
1067 /*
1068 * An exec() starts a new thread group with the
1069 * TGID of the previous thread group. Rehash the
1070 * two threads with a switched PID, and release
1071 * the former thread group leader:
1072 */
1073
1074 /* Become a process group leader with the old leader's pid.
1075 * The old leader becomes a thread of the this thread group.
1076 * Note: The old leader also uses this pid until release_task
1077 * is called. Odd but simple and correct.
1078 */
1079 tsk->pid = leader->pid;
1080 change_pid(tsk, PIDTYPE_PID, task_pid(leader));
1081 transfer_pid(leader, tsk, PIDTYPE_PGID);
1082 transfer_pid(leader, tsk, PIDTYPE_SID);
1083
1084 list_replace_rcu(&leader->tasks, &tsk->tasks);
1085 list_replace_init(&leader->sibling, &tsk->sibling);
1086
1087 tsk->group_leader = tsk;
1088 leader->group_leader = tsk;
1089
1090 tsk->exit_signal = SIGCHLD;
1091 leader->exit_signal = -1;
1092
1093 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
1094 leader->exit_state = EXIT_DEAD;
1095
1096 /*
1097 * We are going to release_task()->ptrace_unlink() silently,
1098 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
1099 * the tracer wont't block again waiting for this thread.
1100 */
1101 if (unlikely(leader->ptrace))
1102 __wake_up_parent(leader, leader->parent);
1103 write_unlock_irq(&tasklist_lock);
1104 threadgroup_change_end(tsk);
1105
1106 release_task(leader);
1107 }
1108
1109 sig->group_exit_task = NULL;
1110 sig->notify_count = 0;
1111
1112no_thread_group:
1113 /* we have changed execution domain */
1114 tsk->exit_signal = SIGCHLD;
1115
1116 exit_itimers(sig);
1117 flush_itimer_signals();
1118
1119 if (atomic_read(&oldsighand->count) != 1) {
1120 struct sighand_struct *newsighand;
1121 /*
1122 * This ->sighand is shared with the CLONE_SIGHAND
1123 * but not CLONE_THREAD task, switch to the new one.
1124 */
1125 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1126 if (!newsighand)
1127 return -ENOMEM;
1128
1129 atomic_set(&newsighand->count, 1);
1130 memcpy(newsighand->action, oldsighand->action,
1131 sizeof(newsighand->action));
1132
1133 write_lock_irq(&tasklist_lock);
1134 spin_lock(&oldsighand->siglock);
1135 rcu_assign_pointer(tsk->sighand, newsighand);
1136 spin_unlock(&oldsighand->siglock);
1137 write_unlock_irq(&tasklist_lock);
1138
1139 __cleanup_sighand(oldsighand);
1140 }
1141
1142 BUG_ON(!thread_group_leader(tsk));
1143 return 0;
1144
1145killed:
1146 /* protects against exit_notify() and __exit_signal() */
1147 read_lock(&tasklist_lock);
1148 sig->group_exit_task = NULL;
1149 sig->notify_count = 0;
1150 read_unlock(&tasklist_lock);
1151 return -EAGAIN;
1152}
1153
1154char *get_task_comm(char *buf, struct task_struct *tsk)
1155{
1156 /* buf must be at least sizeof(tsk->comm) in size */
1157 task_lock(tsk);
1158 strncpy(buf, tsk->comm, sizeof(tsk->comm));
1159 task_unlock(tsk);
1160 return buf;
1161}
1162EXPORT_SYMBOL_GPL(get_task_comm);
1163
1164/*
1165 * These functions flushes out all traces of the currently running executable
1166 * so that a new one can be started
1167 */
1168
1169void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
1170{
1171 task_lock(tsk);
1172 trace_task_rename(tsk, buf);
1173 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1174 task_unlock(tsk);
1175 perf_event_comm(tsk, exec);
1176}
1177
1178int flush_old_exec(struct linux_binprm * bprm)
1179{
1180 int retval;
1181
1182 /*
1183 * Make sure we have a private signal table and that
1184 * we are unassociated from the previous thread group.
1185 */
1186 retval = de_thread(current);
1187 if (retval)
1188 goto out;
1189
1190 /*
1191 * Must be called _before_ exec_mmap() as bprm->mm is
1192 * not visibile until then. This also enables the update
1193 * to be lockless.
1194 */
1195 set_mm_exe_file(bprm->mm, bprm->file);
1196
1197 /*
1198 * Release all of the old mmap stuff
1199 */
1200 acct_arg_size(bprm, 0);
1201 retval = exec_mmap(bprm->mm);
1202 if (retval)
1203 goto out;
1204
1205 bprm->mm = NULL; /* We're using it now */
1206
1207 set_fs(USER_DS);
1208 current->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD |
1209 PF_NOFREEZE | PF_NO_SETAFFINITY);
1210 flush_thread();
1211 current->personality &= ~bprm->per_clear;
1212
1213 return 0;
1214
1215out:
1216 return retval;
1217}
1218EXPORT_SYMBOL(flush_old_exec);
1219
1220void would_dump(struct linux_binprm *bprm, struct file *file)
1221{
1222 if (inode_permission(file_inode(file), MAY_READ) < 0)
1223 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1224}
1225EXPORT_SYMBOL(would_dump);
1226
1227void setup_new_exec(struct linux_binprm * bprm)
1228{
1229 arch_pick_mmap_layout(current->mm);
1230
1231 /* This is the point of no return */
1232 current->sas_ss_sp = current->sas_ss_size = 0;
1233
1234 if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid()))
1235 set_dumpable(current->mm, SUID_DUMP_USER);
1236 else
1237 set_dumpable(current->mm, suid_dumpable);
1238
1239 perf_event_exec();
1240 __set_task_comm(current, kbasename(bprm->filename), true);
1241
1242 /* Set the new mm task size. We have to do that late because it may
1243 * depend on TIF_32BIT which is only updated in flush_thread() on
1244 * some architectures like powerpc
1245 */
1246 current->mm->task_size = TASK_SIZE;
1247
1248 /* install the new credentials */
1249 if (!uid_eq(bprm->cred->uid, current_euid()) ||
1250 !gid_eq(bprm->cred->gid, current_egid())) {
1251 current->pdeath_signal = 0;
1252 } else {
1253 would_dump(bprm, bprm->file);
1254 if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
1255 set_dumpable(current->mm, suid_dumpable);
1256 }
1257
1258 /* An exec changes our domain. We are no longer part of the thread
1259 group */
1260 current->self_exec_id++;
1261 flush_signal_handlers(current, 0);
1262 do_close_on_exec(current->files);
1263}
1264EXPORT_SYMBOL(setup_new_exec);
1265
1266/*
1267 * Prepare credentials and lock ->cred_guard_mutex.
1268 * install_exec_creds() commits the new creds and drops the lock.
1269 * Or, if exec fails before, free_bprm() should release ->cred and
1270 * and unlock.
1271 */
1272int prepare_bprm_creds(struct linux_binprm *bprm)
1273{
1274 if (mutex_lock_interruptible(¤t->signal->cred_guard_mutex))
1275 return -ERESTARTNOINTR;
1276
1277 bprm->cred = prepare_exec_creds();
1278 if (likely(bprm->cred))
1279 return 0;
1280
1281 mutex_unlock(¤t->signal->cred_guard_mutex);
1282 return -ENOMEM;
1283}
1284
1285static void free_bprm(struct linux_binprm *bprm)
1286{
1287 free_arg_pages(bprm);
1288 if (bprm->cred) {
1289 mutex_unlock(¤t->signal->cred_guard_mutex);
1290 abort_creds(bprm->cred);
1291 }
1292 if (bprm->file) {
1293 allow_write_access(bprm->file);
1294 fput(bprm->file);
1295 }
1296 /* If a binfmt changed the interp, free it. */
1297 if (bprm->interp != bprm->filename)
1298 kfree(bprm->interp);
1299 kfree(bprm);
1300}
1301
1302int bprm_change_interp(char *interp, struct linux_binprm *bprm)
1303{
1304 /* If a binfmt changed the interp, free it first. */
1305 if (bprm->interp != bprm->filename)
1306 kfree(bprm->interp);
1307 bprm->interp = kstrdup(interp, GFP_KERNEL);
1308 if (!bprm->interp)
1309 return -ENOMEM;
1310 return 0;
1311}
1312EXPORT_SYMBOL(bprm_change_interp);
1313
1314/*
1315 * install the new credentials for this executable
1316 */
1317void install_exec_creds(struct linux_binprm *bprm)
1318{
1319 security_bprm_committing_creds(bprm);
1320
1321 commit_creds(bprm->cred);
1322 bprm->cred = NULL;
1323
1324 /*
1325 * Disable monitoring for regular users
1326 * when executing setuid binaries. Must
1327 * wait until new credentials are committed
1328 * by commit_creds() above
1329 */
1330 if (get_dumpable(current->mm) != SUID_DUMP_USER)
1331 perf_event_exit_task(current);
1332 /*
1333 * cred_guard_mutex must be held at least to this point to prevent
1334 * ptrace_attach() from altering our determination of the task's
1335 * credentials; any time after this it may be unlocked.
1336 */
1337 security_bprm_committed_creds(bprm);
1338 mutex_unlock(¤t->signal->cred_guard_mutex);
1339}
1340EXPORT_SYMBOL(install_exec_creds);
1341
1342/*
1343 * determine how safe it is to execute the proposed program
1344 * - the caller must hold ->cred_guard_mutex to protect against
1345 * PTRACE_ATTACH or seccomp thread-sync
1346 */
1347static void check_unsafe_exec(struct linux_binprm *bprm)
1348{
1349 struct task_struct *p = current, *t;
1350 unsigned n_fs;
1351
1352 if (p->ptrace) {
1353 if (p->ptrace & PT_PTRACE_CAP)
1354 bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP;
1355 else
1356 bprm->unsafe |= LSM_UNSAFE_PTRACE;
1357 }
1358
1359 /*
1360 * This isn't strictly necessary, but it makes it harder for LSMs to
1361 * mess up.
1362 */
1363 if (task_no_new_privs(current))
1364 bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1365
1366 t = p;
1367 n_fs = 1;
1368 spin_lock(&p->fs->lock);
1369 rcu_read_lock();
1370 while_each_thread(p, t) {
1371 if (t->fs == p->fs)
1372 n_fs++;
1373 }
1374 rcu_read_unlock();
1375
1376 if (p->fs->users > n_fs)
1377 bprm->unsafe |= LSM_UNSAFE_SHARE;
1378 else
1379 p->fs->in_exec = 1;
1380 spin_unlock(&p->fs->lock);
1381}
1382
1383static void bprm_fill_uid(struct linux_binprm *bprm)
1384{
1385 struct inode *inode;
1386 unsigned int mode;
1387 kuid_t uid;
1388 kgid_t gid;
1389
1390 /* clear any previous set[ug]id data from a previous binary */
1391 bprm->cred->euid = current_euid();
1392 bprm->cred->egid = current_egid();
1393
1394 if (bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)
1395 return;
1396
1397 if (task_no_new_privs(current))
1398 return;
1399
1400 inode = file_inode(bprm->file);
1401 mode = READ_ONCE(inode->i_mode);
1402 if (!(mode & (S_ISUID|S_ISGID)))
1403 return;
1404
1405 /* Be careful if suid/sgid is set */
1406 inode_lock(inode);
1407
1408 /* reload atomically mode/uid/gid now that lock held */
1409 mode = inode->i_mode;
1410 uid = inode->i_uid;
1411 gid = inode->i_gid;
1412 inode_unlock(inode);
1413
1414 /* We ignore suid/sgid if there are no mappings for them in the ns */
1415 if (!kuid_has_mapping(bprm->cred->user_ns, uid) ||
1416 !kgid_has_mapping(bprm->cred->user_ns, gid))
1417 return;
1418
1419 if (mode & S_ISUID) {
1420 bprm->per_clear |= PER_CLEAR_ON_SETID;
1421 bprm->cred->euid = uid;
1422 }
1423
1424 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1425 bprm->per_clear |= PER_CLEAR_ON_SETID;
1426 bprm->cred->egid = gid;
1427 }
1428}
1429
1430/*
1431 * Fill the binprm structure from the inode.
1432 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1433 *
1434 * This may be called multiple times for binary chains (scripts for example).
1435 */
1436int prepare_binprm(struct linux_binprm *bprm)
1437{
1438 int retval;
1439
1440 bprm_fill_uid(bprm);
1441
1442 /* fill in binprm security blob */
1443 retval = security_bprm_set_creds(bprm);
1444 if (retval)
1445 return retval;
1446 bprm->cred_prepared = 1;
1447
1448 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1449 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1450}
1451
1452EXPORT_SYMBOL(prepare_binprm);
1453
1454/*
1455 * Arguments are '\0' separated strings found at the location bprm->p
1456 * points to; chop off the first by relocating brpm->p to right after
1457 * the first '\0' encountered.
1458 */
1459int remove_arg_zero(struct linux_binprm *bprm)
1460{
1461 int ret = 0;
1462 unsigned long offset;
1463 char *kaddr;
1464 struct page *page;
1465
1466 if (!bprm->argc)
1467 return 0;
1468
1469 do {
1470 offset = bprm->p & ~PAGE_MASK;
1471 page = get_arg_page(bprm, bprm->p, 0);
1472 if (!page) {
1473 ret = -EFAULT;
1474 goto out;
1475 }
1476 kaddr = kmap_atomic(page);
1477
1478 for (; offset < PAGE_SIZE && kaddr[offset];
1479 offset++, bprm->p++)
1480 ;
1481
1482 kunmap_atomic(kaddr);
1483 put_arg_page(page);
1484
1485 if (offset == PAGE_SIZE)
1486 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1487 } while (offset == PAGE_SIZE);
1488
1489 bprm->p++;
1490 bprm->argc--;
1491 ret = 0;
1492
1493out:
1494 return ret;
1495}
1496EXPORT_SYMBOL(remove_arg_zero);
1497
1498#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1499/*
1500 * cycle the list of binary formats handler, until one recognizes the image
1501 */
1502int search_binary_handler(struct linux_binprm *bprm)
1503{
1504 bool need_retry = IS_ENABLED(CONFIG_MODULES);
1505 struct linux_binfmt *fmt;
1506 int retval;
1507
1508 /* This allows 4 levels of binfmt rewrites before failing hard. */
1509 if (bprm->recursion_depth > 5)
1510 return -ELOOP;
1511
1512 retval = security_bprm_check(bprm);
1513 if (retval)
1514 return retval;
1515
1516 retval = -ENOENT;
1517 retry:
1518 read_lock(&binfmt_lock);
1519 list_for_each_entry(fmt, &formats, lh) {
1520 if (!try_module_get(fmt->module))
1521 continue;
1522 read_unlock(&binfmt_lock);
1523 bprm->recursion_depth++;
1524 retval = fmt->load_binary(bprm);
1525 read_lock(&binfmt_lock);
1526 put_binfmt(fmt);
1527 bprm->recursion_depth--;
1528 if (retval < 0 && !bprm->mm) {
1529 /* we got to flush_old_exec() and failed after it */
1530 read_unlock(&binfmt_lock);
1531 force_sigsegv(SIGSEGV, current);
1532 return retval;
1533 }
1534 if (retval != -ENOEXEC || !bprm->file) {
1535 read_unlock(&binfmt_lock);
1536 return retval;
1537 }
1538 }
1539 read_unlock(&binfmt_lock);
1540
1541 if (need_retry) {
1542 if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
1543 printable(bprm->buf[2]) && printable(bprm->buf[3]))
1544 return retval;
1545 if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
1546 return retval;
1547 need_retry = false;
1548 goto retry;
1549 }
1550
1551 return retval;
1552}
1553EXPORT_SYMBOL(search_binary_handler);
1554
1555static int exec_binprm(struct linux_binprm *bprm)
1556{
1557 pid_t old_pid, old_vpid;
1558 int ret;
1559
1560 /* Need to fetch pid before load_binary changes it */
1561 old_pid = current->pid;
1562 rcu_read_lock();
1563 old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1564 rcu_read_unlock();
1565
1566 ret = search_binary_handler(bprm);
1567 if (ret >= 0) {
1568 audit_bprm(bprm);
1569 trace_sched_process_exec(current, old_pid, bprm);
1570 ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1571 proc_exec_connector(current);
1572 }
1573
1574 return ret;
1575}
1576
1577/*
1578 * sys_execve() executes a new program.
1579 */
1580static int do_execveat_common(int fd, struct filename *filename,
1581 struct user_arg_ptr argv,
1582 struct user_arg_ptr envp,
1583 int flags)
1584{
1585 char *pathbuf = NULL;
1586 struct linux_binprm *bprm;
1587 struct file *file;
1588 struct files_struct *displaced;
1589 int retval;
1590
1591 if (IS_ERR(filename))
1592 return PTR_ERR(filename);
1593
1594 /*
1595 * We move the actual failure in case of RLIMIT_NPROC excess from
1596 * set*uid() to execve() because too many poorly written programs
1597 * don't check setuid() return code. Here we additionally recheck
1598 * whether NPROC limit is still exceeded.
1599 */
1600 if ((current->flags & PF_NPROC_EXCEEDED) &&
1601 atomic_read(¤t_user()->processes) > rlimit(RLIMIT_NPROC)) {
1602 retval = -EAGAIN;
1603 goto out_ret;
1604 }
1605
1606 /* We're below the limit (still or again), so we don't want to make
1607 * further execve() calls fail. */
1608 current->flags &= ~PF_NPROC_EXCEEDED;
1609
1610 retval = unshare_files(&displaced);
1611 if (retval)
1612 goto out_ret;
1613
1614 retval = -ENOMEM;
1615 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1616 if (!bprm)
1617 goto out_files;
1618
1619 retval = prepare_bprm_creds(bprm);
1620 if (retval)
1621 goto out_free;
1622
1623 check_unsafe_exec(bprm);
1624 current->in_execve = 1;
1625
1626 file = do_open_execat(fd, filename, flags);
1627 retval = PTR_ERR(file);
1628 if (IS_ERR(file))
1629 goto out_unmark;
1630
1631 sched_exec();
1632
1633 bprm->file = file;
1634 if (fd == AT_FDCWD || filename->name[0] == '/') {
1635 bprm->filename = filename->name;
1636 } else {
1637 if (filename->name[0] == '\0')
1638 pathbuf = kasprintf(GFP_TEMPORARY, "/dev/fd/%d", fd);
1639 else
1640 pathbuf = kasprintf(GFP_TEMPORARY, "/dev/fd/%d/%s",
1641 fd, filename->name);
1642 if (!pathbuf) {
1643 retval = -ENOMEM;
1644 goto out_unmark;
1645 }
1646 /*
1647 * Record that a name derived from an O_CLOEXEC fd will be
1648 * inaccessible after exec. Relies on having exclusive access to
1649 * current->files (due to unshare_files above).
1650 */
1651 if (close_on_exec(fd, rcu_dereference_raw(current->files->fdt)))
1652 bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;
1653 bprm->filename = pathbuf;
1654 }
1655 bprm->interp = bprm->filename;
1656
1657 retval = bprm_mm_init(bprm);
1658 if (retval)
1659 goto out_unmark;
1660
1661 bprm->argc = count(argv, MAX_ARG_STRINGS);
1662 if ((retval = bprm->argc) < 0)
1663 goto out;
1664
1665 bprm->envc = count(envp, MAX_ARG_STRINGS);
1666 if ((retval = bprm->envc) < 0)
1667 goto out;
1668
1669 retval = prepare_binprm(bprm);
1670 if (retval < 0)
1671 goto out;
1672
1673 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1674 if (retval < 0)
1675 goto out;
1676
1677 bprm->exec = bprm->p;
1678 retval = copy_strings(bprm->envc, envp, bprm);
1679 if (retval < 0)
1680 goto out;
1681
1682 retval = copy_strings(bprm->argc, argv, bprm);
1683 if (retval < 0)
1684 goto out;
1685
1686 retval = exec_binprm(bprm);
1687 if (retval < 0)
1688 goto out;
1689
1690 /* execve succeeded */
1691 current->fs->in_exec = 0;
1692 current->in_execve = 0;
1693 acct_update_integrals(current);
1694 task_numa_free(current);
1695 free_bprm(bprm);
1696 kfree(pathbuf);
1697 putname(filename);
1698 if (displaced)
1699 put_files_struct(displaced);
1700 return retval;
1701
1702out:
1703 if (bprm->mm) {
1704 acct_arg_size(bprm, 0);
1705 mmput(bprm->mm);
1706 }
1707
1708out_unmark:
1709 current->fs->in_exec = 0;
1710 current->in_execve = 0;
1711
1712out_free:
1713 free_bprm(bprm);
1714 kfree(pathbuf);
1715
1716out_files:
1717 if (displaced)
1718 reset_files_struct(displaced);
1719out_ret:
1720 putname(filename);
1721 return retval;
1722}
1723
1724int do_execve(struct filename *filename,
1725 const char __user *const __user *__argv,
1726 const char __user *const __user *__envp)
1727{
1728 struct user_arg_ptr argv = { .ptr.native = __argv };
1729 struct user_arg_ptr envp = { .ptr.native = __envp };
1730 return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
1731}
1732
1733int do_execveat(int fd, struct filename *filename,
1734 const char __user *const __user *__argv,
1735 const char __user *const __user *__envp,
1736 int flags)
1737{
1738 struct user_arg_ptr argv = { .ptr.native = __argv };
1739 struct user_arg_ptr envp = { .ptr.native = __envp };
1740
1741 return do_execveat_common(fd, filename, argv, envp, flags);
1742}
1743
1744#ifdef CONFIG_COMPAT
1745static int compat_do_execve(struct filename *filename,
1746 const compat_uptr_t __user *__argv,
1747 const compat_uptr_t __user *__envp)
1748{
1749 struct user_arg_ptr argv = {
1750 .is_compat = true,
1751 .ptr.compat = __argv,
1752 };
1753 struct user_arg_ptr envp = {
1754 .is_compat = true,
1755 .ptr.compat = __envp,
1756 };
1757 return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
1758}
1759
1760static int compat_do_execveat(int fd, struct filename *filename,
1761 const compat_uptr_t __user *__argv,
1762 const compat_uptr_t __user *__envp,
1763 int flags)
1764{
1765 struct user_arg_ptr argv = {
1766 .is_compat = true,
1767 .ptr.compat = __argv,
1768 };
1769 struct user_arg_ptr envp = {
1770 .is_compat = true,
1771 .ptr.compat = __envp,
1772 };
1773 return do_execveat_common(fd, filename, argv, envp, flags);
1774}
1775#endif
1776
1777void set_binfmt(struct linux_binfmt *new)
1778{
1779 struct mm_struct *mm = current->mm;
1780
1781 if (mm->binfmt)
1782 module_put(mm->binfmt->module);
1783
1784 mm->binfmt = new;
1785 if (new)
1786 __module_get(new->module);
1787}
1788EXPORT_SYMBOL(set_binfmt);
1789
1790/*
1791 * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
1792 */
1793void set_dumpable(struct mm_struct *mm, int value)
1794{
1795 unsigned long old, new;
1796
1797 if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
1798 return;
1799
1800 do {
1801 old = ACCESS_ONCE(mm->flags);
1802 new = (old & ~MMF_DUMPABLE_MASK) | value;
1803 } while (cmpxchg(&mm->flags, old, new) != old);
1804}
1805
1806SYSCALL_DEFINE3(execve,
1807 const char __user *, filename,
1808 const char __user *const __user *, argv,
1809 const char __user *const __user *, envp)
1810{
1811 return do_execve(getname(filename), argv, envp);
1812}
1813
1814SYSCALL_DEFINE5(execveat,
1815 int, fd, const char __user *, filename,
1816 const char __user *const __user *, argv,
1817 const char __user *const __user *, envp,
1818 int, flags)
1819{
1820 int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
1821
1822 return do_execveat(fd,
1823 getname_flags(filename, lookup_flags, NULL),
1824 argv, envp, flags);
1825}
1826
1827#ifdef CONFIG_COMPAT
1828COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
1829 const compat_uptr_t __user *, argv,
1830 const compat_uptr_t __user *, envp)
1831{
1832 return compat_do_execve(getname(filename), argv, envp);
1833}
1834
1835COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
1836 const char __user *, filename,
1837 const compat_uptr_t __user *, argv,
1838 const compat_uptr_t __user *, envp,
1839 int, flags)
1840{
1841 int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
1842
1843 return compat_do_execveat(fd,
1844 getname_flags(filename, lookup_flags, NULL),
1845 argv, envp, flags);
1846}
1847#endif
1/*
2 * linux/fs/exec.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7/*
8 * #!-checking implemented by tytso.
9 */
10/*
11 * Demand-loading implemented 01.12.91 - no need to read anything but
12 * the header into memory. The inode of the executable is put into
13 * "current->executable", and page faults do the actual loading. Clean.
14 *
15 * Once more I can proudly say that linux stood up to being changed: it
16 * was less than 2 hours work to get demand-loading completely implemented.
17 *
18 * Demand loading changed July 1993 by Eric Youngdale. Use mmap instead,
19 * current->executable is only used by the procfs. This allows a dispatch
20 * table to check for several different types of binary formats. We keep
21 * trying until we recognize the file or we run out of supported binary
22 * formats.
23 */
24
25#include <linux/slab.h>
26#include <linux/file.h>
27#include <linux/fdtable.h>
28#include <linux/mm.h>
29#include <linux/stat.h>
30#include <linux/fcntl.h>
31#include <linux/swap.h>
32#include <linux/string.h>
33#include <linux/init.h>
34#include <linux/pagemap.h>
35#include <linux/perf_event.h>
36#include <linux/highmem.h>
37#include <linux/spinlock.h>
38#include <linux/key.h>
39#include <linux/personality.h>
40#include <linux/binfmts.h>
41#include <linux/utsname.h>
42#include <linux/pid_namespace.h>
43#include <linux/module.h>
44#include <linux/namei.h>
45#include <linux/mount.h>
46#include <linux/security.h>
47#include <linux/syscalls.h>
48#include <linux/tsacct_kern.h>
49#include <linux/cn_proc.h>
50#include <linux/audit.h>
51#include <linux/tracehook.h>
52#include <linux/kmod.h>
53#include <linux/fsnotify.h>
54#include <linux/fs_struct.h>
55#include <linux/pipe_fs_i.h>
56#include <linux/oom.h>
57#include <linux/compat.h>
58
59#include <asm/uaccess.h>
60#include <asm/mmu_context.h>
61#include <asm/tlb.h>
62#include "internal.h"
63
64int core_uses_pid;
65char core_pattern[CORENAME_MAX_SIZE] = "core";
66unsigned int core_pipe_limit;
67int suid_dumpable = 0;
68
69struct core_name {
70 char *corename;
71 int used, size;
72};
73static atomic_t call_count = ATOMIC_INIT(1);
74
75/* The maximal length of core_pattern is also specified in sysctl.c */
76
77static LIST_HEAD(formats);
78static DEFINE_RWLOCK(binfmt_lock);
79
80int __register_binfmt(struct linux_binfmt * fmt, int insert)
81{
82 if (!fmt)
83 return -EINVAL;
84 write_lock(&binfmt_lock);
85 insert ? list_add(&fmt->lh, &formats) :
86 list_add_tail(&fmt->lh, &formats);
87 write_unlock(&binfmt_lock);
88 return 0;
89}
90
91EXPORT_SYMBOL(__register_binfmt);
92
93void unregister_binfmt(struct linux_binfmt * fmt)
94{
95 write_lock(&binfmt_lock);
96 list_del(&fmt->lh);
97 write_unlock(&binfmt_lock);
98}
99
100EXPORT_SYMBOL(unregister_binfmt);
101
102static inline void put_binfmt(struct linux_binfmt * fmt)
103{
104 module_put(fmt->module);
105}
106
107/*
108 * Note that a shared library must be both readable and executable due to
109 * security reasons.
110 *
111 * Also note that we take the address to load from from the file itself.
112 */
113SYSCALL_DEFINE1(uselib, const char __user *, library)
114{
115 struct file *file;
116 char *tmp = getname(library);
117 int error = PTR_ERR(tmp);
118 static const struct open_flags uselib_flags = {
119 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
120 .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN,
121 .intent = LOOKUP_OPEN
122 };
123
124 if (IS_ERR(tmp))
125 goto out;
126
127 file = do_filp_open(AT_FDCWD, tmp, &uselib_flags, LOOKUP_FOLLOW);
128 putname(tmp);
129 error = PTR_ERR(file);
130 if (IS_ERR(file))
131 goto out;
132
133 error = -EINVAL;
134 if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
135 goto exit;
136
137 error = -EACCES;
138 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
139 goto exit;
140
141 fsnotify_open(file);
142
143 error = -ENOEXEC;
144 if(file->f_op) {
145 struct linux_binfmt * fmt;
146
147 read_lock(&binfmt_lock);
148 list_for_each_entry(fmt, &formats, lh) {
149 if (!fmt->load_shlib)
150 continue;
151 if (!try_module_get(fmt->module))
152 continue;
153 read_unlock(&binfmt_lock);
154 error = fmt->load_shlib(file);
155 read_lock(&binfmt_lock);
156 put_binfmt(fmt);
157 if (error != -ENOEXEC)
158 break;
159 }
160 read_unlock(&binfmt_lock);
161 }
162exit:
163 fput(file);
164out:
165 return error;
166}
167
168#ifdef CONFIG_MMU
169/*
170 * The nascent bprm->mm is not visible until exec_mmap() but it can
171 * use a lot of memory, account these pages in current->mm temporary
172 * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
173 * change the counter back via acct_arg_size(0).
174 */
175static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
176{
177 struct mm_struct *mm = current->mm;
178 long diff = (long)(pages - bprm->vma_pages);
179
180 if (!mm || !diff)
181 return;
182
183 bprm->vma_pages = pages;
184 add_mm_counter(mm, MM_ANONPAGES, diff);
185}
186
187static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
188 int write)
189{
190 struct page *page;
191 int ret;
192
193#ifdef CONFIG_STACK_GROWSUP
194 if (write) {
195 ret = expand_downwards(bprm->vma, pos);
196 if (ret < 0)
197 return NULL;
198 }
199#endif
200 ret = get_user_pages(current, bprm->mm, pos,
201 1, write, 1, &page, NULL);
202 if (ret <= 0)
203 return NULL;
204
205 if (write) {
206 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
207 struct rlimit *rlim;
208
209 acct_arg_size(bprm, size / PAGE_SIZE);
210
211 /*
212 * We've historically supported up to 32 pages (ARG_MAX)
213 * of argument strings even with small stacks
214 */
215 if (size <= ARG_MAX)
216 return page;
217
218 /*
219 * Limit to 1/4-th the stack size for the argv+env strings.
220 * This ensures that:
221 * - the remaining binfmt code will not run out of stack space,
222 * - the program will have a reasonable amount of stack left
223 * to work from.
224 */
225 rlim = current->signal->rlim;
226 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
227 put_page(page);
228 return NULL;
229 }
230 }
231
232 return page;
233}
234
235static void put_arg_page(struct page *page)
236{
237 put_page(page);
238}
239
240static void free_arg_page(struct linux_binprm *bprm, int i)
241{
242}
243
244static void free_arg_pages(struct linux_binprm *bprm)
245{
246}
247
248static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
249 struct page *page)
250{
251 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
252}
253
254static int __bprm_mm_init(struct linux_binprm *bprm)
255{
256 int err;
257 struct vm_area_struct *vma = NULL;
258 struct mm_struct *mm = bprm->mm;
259
260 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
261 if (!vma)
262 return -ENOMEM;
263
264 down_write(&mm->mmap_sem);
265 vma->vm_mm = mm;
266
267 /*
268 * Place the stack at the largest stack address the architecture
269 * supports. Later, we'll move this to an appropriate place. We don't
270 * use STACK_TOP because that can depend on attributes which aren't
271 * configured yet.
272 */
273 BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
274 vma->vm_end = STACK_TOP_MAX;
275 vma->vm_start = vma->vm_end - PAGE_SIZE;
276 vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
277 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
278 INIT_LIST_HEAD(&vma->anon_vma_chain);
279
280 err = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1);
281 if (err)
282 goto err;
283
284 err = insert_vm_struct(mm, vma);
285 if (err)
286 goto err;
287
288 mm->stack_vm = mm->total_vm = 1;
289 up_write(&mm->mmap_sem);
290 bprm->p = vma->vm_end - sizeof(void *);
291 return 0;
292err:
293 up_write(&mm->mmap_sem);
294 bprm->vma = NULL;
295 kmem_cache_free(vm_area_cachep, vma);
296 return err;
297}
298
299static bool valid_arg_len(struct linux_binprm *bprm, long len)
300{
301 return len <= MAX_ARG_STRLEN;
302}
303
304#else
305
306static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
307{
308}
309
310static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
311 int write)
312{
313 struct page *page;
314
315 page = bprm->page[pos / PAGE_SIZE];
316 if (!page && write) {
317 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
318 if (!page)
319 return NULL;
320 bprm->page[pos / PAGE_SIZE] = page;
321 }
322
323 return page;
324}
325
326static void put_arg_page(struct page *page)
327{
328}
329
330static void free_arg_page(struct linux_binprm *bprm, int i)
331{
332 if (bprm->page[i]) {
333 __free_page(bprm->page[i]);
334 bprm->page[i] = NULL;
335 }
336}
337
338static void free_arg_pages(struct linux_binprm *bprm)
339{
340 int i;
341
342 for (i = 0; i < MAX_ARG_PAGES; i++)
343 free_arg_page(bprm, i);
344}
345
346static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
347 struct page *page)
348{
349}
350
351static int __bprm_mm_init(struct linux_binprm *bprm)
352{
353 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
354 return 0;
355}
356
357static bool valid_arg_len(struct linux_binprm *bprm, long len)
358{
359 return len <= bprm->p;
360}
361
362#endif /* CONFIG_MMU */
363
364/*
365 * Create a new mm_struct and populate it with a temporary stack
366 * vm_area_struct. We don't have enough context at this point to set the stack
367 * flags, permissions, and offset, so we use temporary values. We'll update
368 * them later in setup_arg_pages().
369 */
370int bprm_mm_init(struct linux_binprm *bprm)
371{
372 int err;
373 struct mm_struct *mm = NULL;
374
375 bprm->mm = mm = mm_alloc();
376 err = -ENOMEM;
377 if (!mm)
378 goto err;
379
380 err = init_new_context(current, mm);
381 if (err)
382 goto err;
383
384 err = __bprm_mm_init(bprm);
385 if (err)
386 goto err;
387
388 return 0;
389
390err:
391 if (mm) {
392 bprm->mm = NULL;
393 mmdrop(mm);
394 }
395
396 return err;
397}
398
399struct user_arg_ptr {
400#ifdef CONFIG_COMPAT
401 bool is_compat;
402#endif
403 union {
404 const char __user *const __user *native;
405#ifdef CONFIG_COMPAT
406 compat_uptr_t __user *compat;
407#endif
408 } ptr;
409};
410
411static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
412{
413 const char __user *native;
414
415#ifdef CONFIG_COMPAT
416 if (unlikely(argv.is_compat)) {
417 compat_uptr_t compat;
418
419 if (get_user(compat, argv.ptr.compat + nr))
420 return ERR_PTR(-EFAULT);
421
422 return compat_ptr(compat);
423 }
424#endif
425
426 if (get_user(native, argv.ptr.native + nr))
427 return ERR_PTR(-EFAULT);
428
429 return native;
430}
431
432/*
433 * count() counts the number of strings in array ARGV.
434 */
435static int count(struct user_arg_ptr argv, int max)
436{
437 int i = 0;
438
439 if (argv.ptr.native != NULL) {
440 for (;;) {
441 const char __user *p = get_user_arg_ptr(argv, i);
442
443 if (!p)
444 break;
445
446 if (IS_ERR(p))
447 return -EFAULT;
448
449 if (i++ >= max)
450 return -E2BIG;
451
452 if (fatal_signal_pending(current))
453 return -ERESTARTNOHAND;
454 cond_resched();
455 }
456 }
457 return i;
458}
459
460/*
461 * 'copy_strings()' copies argument/environment strings from the old
462 * processes's memory to the new process's stack. The call to get_user_pages()
463 * ensures the destination page is created and not swapped out.
464 */
465static int copy_strings(int argc, struct user_arg_ptr argv,
466 struct linux_binprm *bprm)
467{
468 struct page *kmapped_page = NULL;
469 char *kaddr = NULL;
470 unsigned long kpos = 0;
471 int ret;
472
473 while (argc-- > 0) {
474 const char __user *str;
475 int len;
476 unsigned long pos;
477
478 ret = -EFAULT;
479 str = get_user_arg_ptr(argv, argc);
480 if (IS_ERR(str))
481 goto out;
482
483 len = strnlen_user(str, MAX_ARG_STRLEN);
484 if (!len)
485 goto out;
486
487 ret = -E2BIG;
488 if (!valid_arg_len(bprm, len))
489 goto out;
490
491 /* We're going to work our way backwords. */
492 pos = bprm->p;
493 str += len;
494 bprm->p -= len;
495
496 while (len > 0) {
497 int offset, bytes_to_copy;
498
499 if (fatal_signal_pending(current)) {
500 ret = -ERESTARTNOHAND;
501 goto out;
502 }
503 cond_resched();
504
505 offset = pos % PAGE_SIZE;
506 if (offset == 0)
507 offset = PAGE_SIZE;
508
509 bytes_to_copy = offset;
510 if (bytes_to_copy > len)
511 bytes_to_copy = len;
512
513 offset -= bytes_to_copy;
514 pos -= bytes_to_copy;
515 str -= bytes_to_copy;
516 len -= bytes_to_copy;
517
518 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
519 struct page *page;
520
521 page = get_arg_page(bprm, pos, 1);
522 if (!page) {
523 ret = -E2BIG;
524 goto out;
525 }
526
527 if (kmapped_page) {
528 flush_kernel_dcache_page(kmapped_page);
529 kunmap(kmapped_page);
530 put_arg_page(kmapped_page);
531 }
532 kmapped_page = page;
533 kaddr = kmap(kmapped_page);
534 kpos = pos & PAGE_MASK;
535 flush_arg_page(bprm, kpos, kmapped_page);
536 }
537 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
538 ret = -EFAULT;
539 goto out;
540 }
541 }
542 }
543 ret = 0;
544out:
545 if (kmapped_page) {
546 flush_kernel_dcache_page(kmapped_page);
547 kunmap(kmapped_page);
548 put_arg_page(kmapped_page);
549 }
550 return ret;
551}
552
553/*
554 * Like copy_strings, but get argv and its values from kernel memory.
555 */
556int copy_strings_kernel(int argc, const char *const *__argv,
557 struct linux_binprm *bprm)
558{
559 int r;
560 mm_segment_t oldfs = get_fs();
561 struct user_arg_ptr argv = {
562 .ptr.native = (const char __user *const __user *)__argv,
563 };
564
565 set_fs(KERNEL_DS);
566 r = copy_strings(argc, argv, bprm);
567 set_fs(oldfs);
568
569 return r;
570}
571EXPORT_SYMBOL(copy_strings_kernel);
572
573#ifdef CONFIG_MMU
574
575/*
576 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
577 * the binfmt code determines where the new stack should reside, we shift it to
578 * its final location. The process proceeds as follows:
579 *
580 * 1) Use shift to calculate the new vma endpoints.
581 * 2) Extend vma to cover both the old and new ranges. This ensures the
582 * arguments passed to subsequent functions are consistent.
583 * 3) Move vma's page tables to the new range.
584 * 4) Free up any cleared pgd range.
585 * 5) Shrink the vma to cover only the new range.
586 */
587static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
588{
589 struct mm_struct *mm = vma->vm_mm;
590 unsigned long old_start = vma->vm_start;
591 unsigned long old_end = vma->vm_end;
592 unsigned long length = old_end - old_start;
593 unsigned long new_start = old_start - shift;
594 unsigned long new_end = old_end - shift;
595 struct mmu_gather tlb;
596
597 BUG_ON(new_start > new_end);
598
599 /*
600 * ensure there are no vmas between where we want to go
601 * and where we are
602 */
603 if (vma != find_vma(mm, new_start))
604 return -EFAULT;
605
606 /*
607 * cover the whole range: [new_start, old_end)
608 */
609 if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
610 return -ENOMEM;
611
612 /*
613 * move the page tables downwards, on failure we rely on
614 * process cleanup to remove whatever mess we made.
615 */
616 if (length != move_page_tables(vma, old_start,
617 vma, new_start, length))
618 return -ENOMEM;
619
620 lru_add_drain();
621 tlb_gather_mmu(&tlb, mm, 0);
622 if (new_end > old_start) {
623 /*
624 * when the old and new regions overlap clear from new_end.
625 */
626 free_pgd_range(&tlb, new_end, old_end, new_end,
627 vma->vm_next ? vma->vm_next->vm_start : 0);
628 } else {
629 /*
630 * otherwise, clean from old_start; this is done to not touch
631 * the address space in [new_end, old_start) some architectures
632 * have constraints on va-space that make this illegal (IA64) -
633 * for the others its just a little faster.
634 */
635 free_pgd_range(&tlb, old_start, old_end, new_end,
636 vma->vm_next ? vma->vm_next->vm_start : 0);
637 }
638 tlb_finish_mmu(&tlb, new_end, old_end);
639
640 /*
641 * Shrink the vma to just the new range. Always succeeds.
642 */
643 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
644
645 return 0;
646}
647
648/*
649 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
650 * the stack is optionally relocated, and some extra space is added.
651 */
652int setup_arg_pages(struct linux_binprm *bprm,
653 unsigned long stack_top,
654 int executable_stack)
655{
656 unsigned long ret;
657 unsigned long stack_shift;
658 struct mm_struct *mm = current->mm;
659 struct vm_area_struct *vma = bprm->vma;
660 struct vm_area_struct *prev = NULL;
661 unsigned long vm_flags;
662 unsigned long stack_base;
663 unsigned long stack_size;
664 unsigned long stack_expand;
665 unsigned long rlim_stack;
666
667#ifdef CONFIG_STACK_GROWSUP
668 /* Limit stack size to 1GB */
669 stack_base = rlimit_max(RLIMIT_STACK);
670 if (stack_base > (1 << 30))
671 stack_base = 1 << 30;
672
673 /* Make sure we didn't let the argument array grow too large. */
674 if (vma->vm_end - vma->vm_start > stack_base)
675 return -ENOMEM;
676
677 stack_base = PAGE_ALIGN(stack_top - stack_base);
678
679 stack_shift = vma->vm_start - stack_base;
680 mm->arg_start = bprm->p - stack_shift;
681 bprm->p = vma->vm_end - stack_shift;
682#else
683 stack_top = arch_align_stack(stack_top);
684 stack_top = PAGE_ALIGN(stack_top);
685
686 if (unlikely(stack_top < mmap_min_addr) ||
687 unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
688 return -ENOMEM;
689
690 stack_shift = vma->vm_end - stack_top;
691
692 bprm->p -= stack_shift;
693 mm->arg_start = bprm->p;
694#endif
695
696 if (bprm->loader)
697 bprm->loader -= stack_shift;
698 bprm->exec -= stack_shift;
699
700 down_write(&mm->mmap_sem);
701 vm_flags = VM_STACK_FLAGS;
702
703 /*
704 * Adjust stack execute permissions; explicitly enable for
705 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
706 * (arch default) otherwise.
707 */
708 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
709 vm_flags |= VM_EXEC;
710 else if (executable_stack == EXSTACK_DISABLE_X)
711 vm_flags &= ~VM_EXEC;
712 vm_flags |= mm->def_flags;
713 vm_flags |= VM_STACK_INCOMPLETE_SETUP;
714
715 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
716 vm_flags);
717 if (ret)
718 goto out_unlock;
719 BUG_ON(prev != vma);
720
721 /* Move stack pages down in memory. */
722 if (stack_shift) {
723 ret = shift_arg_pages(vma, stack_shift);
724 if (ret)
725 goto out_unlock;
726 }
727
728 /* mprotect_fixup is overkill to remove the temporary stack flags */
729 vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
730
731 stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
732 stack_size = vma->vm_end - vma->vm_start;
733 /*
734 * Align this down to a page boundary as expand_stack
735 * will align it up.
736 */
737 rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
738#ifdef CONFIG_STACK_GROWSUP
739 if (stack_size + stack_expand > rlim_stack)
740 stack_base = vma->vm_start + rlim_stack;
741 else
742 stack_base = vma->vm_end + stack_expand;
743#else
744 if (stack_size + stack_expand > rlim_stack)
745 stack_base = vma->vm_end - rlim_stack;
746 else
747 stack_base = vma->vm_start - stack_expand;
748#endif
749 current->mm->start_stack = bprm->p;
750 ret = expand_stack(vma, stack_base);
751 if (ret)
752 ret = -EFAULT;
753
754out_unlock:
755 up_write(&mm->mmap_sem);
756 return ret;
757}
758EXPORT_SYMBOL(setup_arg_pages);
759
760#endif /* CONFIG_MMU */
761
762struct file *open_exec(const char *name)
763{
764 struct file *file;
765 int err;
766 static const struct open_flags open_exec_flags = {
767 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
768 .acc_mode = MAY_EXEC | MAY_OPEN,
769 .intent = LOOKUP_OPEN
770 };
771
772 file = do_filp_open(AT_FDCWD, name, &open_exec_flags, LOOKUP_FOLLOW);
773 if (IS_ERR(file))
774 goto out;
775
776 err = -EACCES;
777 if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
778 goto exit;
779
780 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
781 goto exit;
782
783 fsnotify_open(file);
784
785 err = deny_write_access(file);
786 if (err)
787 goto exit;
788
789out:
790 return file;
791
792exit:
793 fput(file);
794 return ERR_PTR(err);
795}
796EXPORT_SYMBOL(open_exec);
797
798int kernel_read(struct file *file, loff_t offset,
799 char *addr, unsigned long count)
800{
801 mm_segment_t old_fs;
802 loff_t pos = offset;
803 int result;
804
805 old_fs = get_fs();
806 set_fs(get_ds());
807 /* The cast to a user pointer is valid due to the set_fs() */
808 result = vfs_read(file, (void __user *)addr, count, &pos);
809 set_fs(old_fs);
810 return result;
811}
812
813EXPORT_SYMBOL(kernel_read);
814
815static int exec_mmap(struct mm_struct *mm)
816{
817 struct task_struct *tsk;
818 struct mm_struct * old_mm, *active_mm;
819
820 /* Notify parent that we're no longer interested in the old VM */
821 tsk = current;
822 old_mm = current->mm;
823 sync_mm_rss(tsk, old_mm);
824 mm_release(tsk, old_mm);
825
826 if (old_mm) {
827 /*
828 * Make sure that if there is a core dump in progress
829 * for the old mm, we get out and die instead of going
830 * through with the exec. We must hold mmap_sem around
831 * checking core_state and changing tsk->mm.
832 */
833 down_read(&old_mm->mmap_sem);
834 if (unlikely(old_mm->core_state)) {
835 up_read(&old_mm->mmap_sem);
836 return -EINTR;
837 }
838 }
839 task_lock(tsk);
840 active_mm = tsk->active_mm;
841 tsk->mm = mm;
842 tsk->active_mm = mm;
843 activate_mm(active_mm, mm);
844 if (old_mm && tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) {
845 atomic_dec(&old_mm->oom_disable_count);
846 atomic_inc(&tsk->mm->oom_disable_count);
847 }
848 task_unlock(tsk);
849 arch_pick_mmap_layout(mm);
850 if (old_mm) {
851 up_read(&old_mm->mmap_sem);
852 BUG_ON(active_mm != old_mm);
853 mm_update_next_owner(old_mm);
854 mmput(old_mm);
855 return 0;
856 }
857 mmdrop(active_mm);
858 return 0;
859}
860
861/*
862 * This function makes sure the current process has its own signal table,
863 * so that flush_signal_handlers can later reset the handlers without
864 * disturbing other processes. (Other processes might share the signal
865 * table via the CLONE_SIGHAND option to clone().)
866 */
867static int de_thread(struct task_struct *tsk)
868{
869 struct signal_struct *sig = tsk->signal;
870 struct sighand_struct *oldsighand = tsk->sighand;
871 spinlock_t *lock = &oldsighand->siglock;
872
873 if (thread_group_empty(tsk))
874 goto no_thread_group;
875
876 /*
877 * Kill all other threads in the thread group.
878 */
879 spin_lock_irq(lock);
880 if (signal_group_exit(sig)) {
881 /*
882 * Another group action in progress, just
883 * return so that the signal is processed.
884 */
885 spin_unlock_irq(lock);
886 return -EAGAIN;
887 }
888
889 sig->group_exit_task = tsk;
890 sig->notify_count = zap_other_threads(tsk);
891 if (!thread_group_leader(tsk))
892 sig->notify_count--;
893
894 while (sig->notify_count) {
895 __set_current_state(TASK_UNINTERRUPTIBLE);
896 spin_unlock_irq(lock);
897 schedule();
898 spin_lock_irq(lock);
899 }
900 spin_unlock_irq(lock);
901
902 /*
903 * At this point all other threads have exited, all we have to
904 * do is to wait for the thread group leader to become inactive,
905 * and to assume its PID:
906 */
907 if (!thread_group_leader(tsk)) {
908 struct task_struct *leader = tsk->group_leader;
909
910 sig->notify_count = -1; /* for exit_notify() */
911 for (;;) {
912 write_lock_irq(&tasklist_lock);
913 if (likely(leader->exit_state))
914 break;
915 __set_current_state(TASK_UNINTERRUPTIBLE);
916 write_unlock_irq(&tasklist_lock);
917 schedule();
918 }
919
920 /*
921 * The only record we have of the real-time age of a
922 * process, regardless of execs it's done, is start_time.
923 * All the past CPU time is accumulated in signal_struct
924 * from sister threads now dead. But in this non-leader
925 * exec, nothing survives from the original leader thread,
926 * whose birth marks the true age of this process now.
927 * When we take on its identity by switching to its PID, we
928 * also take its birthdate (always earlier than our own).
929 */
930 tsk->start_time = leader->start_time;
931
932 BUG_ON(!same_thread_group(leader, tsk));
933 BUG_ON(has_group_leader_pid(tsk));
934 /*
935 * An exec() starts a new thread group with the
936 * TGID of the previous thread group. Rehash the
937 * two threads with a switched PID, and release
938 * the former thread group leader:
939 */
940
941 /* Become a process group leader with the old leader's pid.
942 * The old leader becomes a thread of the this thread group.
943 * Note: The old leader also uses this pid until release_task
944 * is called. Odd but simple and correct.
945 */
946 detach_pid(tsk, PIDTYPE_PID);
947 tsk->pid = leader->pid;
948 attach_pid(tsk, PIDTYPE_PID, task_pid(leader));
949 transfer_pid(leader, tsk, PIDTYPE_PGID);
950 transfer_pid(leader, tsk, PIDTYPE_SID);
951
952 list_replace_rcu(&leader->tasks, &tsk->tasks);
953 list_replace_init(&leader->sibling, &tsk->sibling);
954
955 tsk->group_leader = tsk;
956 leader->group_leader = tsk;
957
958 tsk->exit_signal = SIGCHLD;
959 leader->exit_signal = -1;
960
961 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
962 leader->exit_state = EXIT_DEAD;
963
964 /*
965 * We are going to release_task()->ptrace_unlink() silently,
966 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
967 * the tracer wont't block again waiting for this thread.
968 */
969 if (unlikely(leader->ptrace))
970 __wake_up_parent(leader, leader->parent);
971 write_unlock_irq(&tasklist_lock);
972
973 release_task(leader);
974 }
975
976 sig->group_exit_task = NULL;
977 sig->notify_count = 0;
978
979no_thread_group:
980 if (current->mm)
981 setmax_mm_hiwater_rss(&sig->maxrss, current->mm);
982
983 exit_itimers(sig);
984 flush_itimer_signals();
985
986 if (atomic_read(&oldsighand->count) != 1) {
987 struct sighand_struct *newsighand;
988 /*
989 * This ->sighand is shared with the CLONE_SIGHAND
990 * but not CLONE_THREAD task, switch to the new one.
991 */
992 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
993 if (!newsighand)
994 return -ENOMEM;
995
996 atomic_set(&newsighand->count, 1);
997 memcpy(newsighand->action, oldsighand->action,
998 sizeof(newsighand->action));
999
1000 write_lock_irq(&tasklist_lock);
1001 spin_lock(&oldsighand->siglock);
1002 rcu_assign_pointer(tsk->sighand, newsighand);
1003 spin_unlock(&oldsighand->siglock);
1004 write_unlock_irq(&tasklist_lock);
1005
1006 __cleanup_sighand(oldsighand);
1007 }
1008
1009 BUG_ON(!thread_group_leader(tsk));
1010 return 0;
1011}
1012
1013/*
1014 * These functions flushes out all traces of the currently running executable
1015 * so that a new one can be started
1016 */
1017static void flush_old_files(struct files_struct * files)
1018{
1019 long j = -1;
1020 struct fdtable *fdt;
1021
1022 spin_lock(&files->file_lock);
1023 for (;;) {
1024 unsigned long set, i;
1025
1026 j++;
1027 i = j * __NFDBITS;
1028 fdt = files_fdtable(files);
1029 if (i >= fdt->max_fds)
1030 break;
1031 set = fdt->close_on_exec->fds_bits[j];
1032 if (!set)
1033 continue;
1034 fdt->close_on_exec->fds_bits[j] = 0;
1035 spin_unlock(&files->file_lock);
1036 for ( ; set ; i++,set >>= 1) {
1037 if (set & 1) {
1038 sys_close(i);
1039 }
1040 }
1041 spin_lock(&files->file_lock);
1042
1043 }
1044 spin_unlock(&files->file_lock);
1045}
1046
1047char *get_task_comm(char *buf, struct task_struct *tsk)
1048{
1049 /* buf must be at least sizeof(tsk->comm) in size */
1050 task_lock(tsk);
1051 strncpy(buf, tsk->comm, sizeof(tsk->comm));
1052 task_unlock(tsk);
1053 return buf;
1054}
1055EXPORT_SYMBOL_GPL(get_task_comm);
1056
1057void set_task_comm(struct task_struct *tsk, char *buf)
1058{
1059 task_lock(tsk);
1060
1061 /*
1062 * Threads may access current->comm without holding
1063 * the task lock, so write the string carefully.
1064 * Readers without a lock may see incomplete new
1065 * names but are safe from non-terminating string reads.
1066 */
1067 memset(tsk->comm, 0, TASK_COMM_LEN);
1068 wmb();
1069 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1070 task_unlock(tsk);
1071 perf_event_comm(tsk);
1072}
1073
1074int flush_old_exec(struct linux_binprm * bprm)
1075{
1076 int retval;
1077
1078 /*
1079 * Make sure we have a private signal table and that
1080 * we are unassociated from the previous thread group.
1081 */
1082 retval = de_thread(current);
1083 if (retval)
1084 goto out;
1085
1086 set_mm_exe_file(bprm->mm, bprm->file);
1087
1088 /*
1089 * Release all of the old mmap stuff
1090 */
1091 acct_arg_size(bprm, 0);
1092 retval = exec_mmap(bprm->mm);
1093 if (retval)
1094 goto out;
1095
1096 bprm->mm = NULL; /* We're using it now */
1097
1098 set_fs(USER_DS);
1099 current->flags &= ~(PF_RANDOMIZE | PF_KTHREAD);
1100 flush_thread();
1101 current->personality &= ~bprm->per_clear;
1102
1103 return 0;
1104
1105out:
1106 return retval;
1107}
1108EXPORT_SYMBOL(flush_old_exec);
1109
1110void would_dump(struct linux_binprm *bprm, struct file *file)
1111{
1112 if (inode_permission(file->f_path.dentry->d_inode, MAY_READ) < 0)
1113 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1114}
1115EXPORT_SYMBOL(would_dump);
1116
1117void setup_new_exec(struct linux_binprm * bprm)
1118{
1119 int i, ch;
1120 const char *name;
1121 char tcomm[sizeof(current->comm)];
1122
1123 arch_pick_mmap_layout(current->mm);
1124
1125 /* This is the point of no return */
1126 current->sas_ss_sp = current->sas_ss_size = 0;
1127
1128 if (current_euid() == current_uid() && current_egid() == current_gid())
1129 set_dumpable(current->mm, 1);
1130 else
1131 set_dumpable(current->mm, suid_dumpable);
1132
1133 name = bprm->filename;
1134
1135 /* Copies the binary name from after last slash */
1136 for (i=0; (ch = *(name++)) != '\0';) {
1137 if (ch == '/')
1138 i = 0; /* overwrite what we wrote */
1139 else
1140 if (i < (sizeof(tcomm) - 1))
1141 tcomm[i++] = ch;
1142 }
1143 tcomm[i] = '\0';
1144 set_task_comm(current, tcomm);
1145
1146 /* Set the new mm task size. We have to do that late because it may
1147 * depend on TIF_32BIT which is only updated in flush_thread() on
1148 * some architectures like powerpc
1149 */
1150 current->mm->task_size = TASK_SIZE;
1151
1152 /* install the new credentials */
1153 if (bprm->cred->uid != current_euid() ||
1154 bprm->cred->gid != current_egid()) {
1155 current->pdeath_signal = 0;
1156 } else {
1157 would_dump(bprm, bprm->file);
1158 if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
1159 set_dumpable(current->mm, suid_dumpable);
1160 }
1161
1162 /*
1163 * Flush performance counters when crossing a
1164 * security domain:
1165 */
1166 if (!get_dumpable(current->mm))
1167 perf_event_exit_task(current);
1168
1169 /* An exec changes our domain. We are no longer part of the thread
1170 group */
1171
1172 current->self_exec_id++;
1173
1174 flush_signal_handlers(current, 0);
1175 flush_old_files(current->files);
1176}
1177EXPORT_SYMBOL(setup_new_exec);
1178
1179/*
1180 * Prepare credentials and lock ->cred_guard_mutex.
1181 * install_exec_creds() commits the new creds and drops the lock.
1182 * Or, if exec fails before, free_bprm() should release ->cred and
1183 * and unlock.
1184 */
1185int prepare_bprm_creds(struct linux_binprm *bprm)
1186{
1187 if (mutex_lock_interruptible(¤t->signal->cred_guard_mutex))
1188 return -ERESTARTNOINTR;
1189
1190 bprm->cred = prepare_exec_creds();
1191 if (likely(bprm->cred))
1192 return 0;
1193
1194 mutex_unlock(¤t->signal->cred_guard_mutex);
1195 return -ENOMEM;
1196}
1197
1198void free_bprm(struct linux_binprm *bprm)
1199{
1200 free_arg_pages(bprm);
1201 if (bprm->cred) {
1202 mutex_unlock(¤t->signal->cred_guard_mutex);
1203 abort_creds(bprm->cred);
1204 }
1205 kfree(bprm);
1206}
1207
1208/*
1209 * install the new credentials for this executable
1210 */
1211void install_exec_creds(struct linux_binprm *bprm)
1212{
1213 security_bprm_committing_creds(bprm);
1214
1215 commit_creds(bprm->cred);
1216 bprm->cred = NULL;
1217 /*
1218 * cred_guard_mutex must be held at least to this point to prevent
1219 * ptrace_attach() from altering our determination of the task's
1220 * credentials; any time after this it may be unlocked.
1221 */
1222 security_bprm_committed_creds(bprm);
1223 mutex_unlock(¤t->signal->cred_guard_mutex);
1224}
1225EXPORT_SYMBOL(install_exec_creds);
1226
1227/*
1228 * determine how safe it is to execute the proposed program
1229 * - the caller must hold ->cred_guard_mutex to protect against
1230 * PTRACE_ATTACH
1231 */
1232int check_unsafe_exec(struct linux_binprm *bprm)
1233{
1234 struct task_struct *p = current, *t;
1235 unsigned n_fs;
1236 int res = 0;
1237
1238 if (p->ptrace) {
1239 if (p->ptrace & PT_PTRACE_CAP)
1240 bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP;
1241 else
1242 bprm->unsafe |= LSM_UNSAFE_PTRACE;
1243 }
1244
1245 n_fs = 1;
1246 spin_lock(&p->fs->lock);
1247 rcu_read_lock();
1248 for (t = next_thread(p); t != p; t = next_thread(t)) {
1249 if (t->fs == p->fs)
1250 n_fs++;
1251 }
1252 rcu_read_unlock();
1253
1254 if (p->fs->users > n_fs) {
1255 bprm->unsafe |= LSM_UNSAFE_SHARE;
1256 } else {
1257 res = -EAGAIN;
1258 if (!p->fs->in_exec) {
1259 p->fs->in_exec = 1;
1260 res = 1;
1261 }
1262 }
1263 spin_unlock(&p->fs->lock);
1264
1265 return res;
1266}
1267
1268/*
1269 * Fill the binprm structure from the inode.
1270 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1271 *
1272 * This may be called multiple times for binary chains (scripts for example).
1273 */
1274int prepare_binprm(struct linux_binprm *bprm)
1275{
1276 umode_t mode;
1277 struct inode * inode = bprm->file->f_path.dentry->d_inode;
1278 int retval;
1279
1280 mode = inode->i_mode;
1281 if (bprm->file->f_op == NULL)
1282 return -EACCES;
1283
1284 /* clear any previous set[ug]id data from a previous binary */
1285 bprm->cred->euid = current_euid();
1286 bprm->cred->egid = current_egid();
1287
1288 if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1289 /* Set-uid? */
1290 if (mode & S_ISUID) {
1291 bprm->per_clear |= PER_CLEAR_ON_SETID;
1292 bprm->cred->euid = inode->i_uid;
1293 }
1294
1295 /* Set-gid? */
1296 /*
1297 * If setgid is set but no group execute bit then this
1298 * is a candidate for mandatory locking, not a setgid
1299 * executable.
1300 */
1301 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1302 bprm->per_clear |= PER_CLEAR_ON_SETID;
1303 bprm->cred->egid = inode->i_gid;
1304 }
1305 }
1306
1307 /* fill in binprm security blob */
1308 retval = security_bprm_set_creds(bprm);
1309 if (retval)
1310 return retval;
1311 bprm->cred_prepared = 1;
1312
1313 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1314 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1315}
1316
1317EXPORT_SYMBOL(prepare_binprm);
1318
1319/*
1320 * Arguments are '\0' separated strings found at the location bprm->p
1321 * points to; chop off the first by relocating brpm->p to right after
1322 * the first '\0' encountered.
1323 */
1324int remove_arg_zero(struct linux_binprm *bprm)
1325{
1326 int ret = 0;
1327 unsigned long offset;
1328 char *kaddr;
1329 struct page *page;
1330
1331 if (!bprm->argc)
1332 return 0;
1333
1334 do {
1335 offset = bprm->p & ~PAGE_MASK;
1336 page = get_arg_page(bprm, bprm->p, 0);
1337 if (!page) {
1338 ret = -EFAULT;
1339 goto out;
1340 }
1341 kaddr = kmap_atomic(page, KM_USER0);
1342
1343 for (; offset < PAGE_SIZE && kaddr[offset];
1344 offset++, bprm->p++)
1345 ;
1346
1347 kunmap_atomic(kaddr, KM_USER0);
1348 put_arg_page(page);
1349
1350 if (offset == PAGE_SIZE)
1351 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1352 } while (offset == PAGE_SIZE);
1353
1354 bprm->p++;
1355 bprm->argc--;
1356 ret = 0;
1357
1358out:
1359 return ret;
1360}
1361EXPORT_SYMBOL(remove_arg_zero);
1362
1363/*
1364 * cycle the list of binary formats handler, until one recognizes the image
1365 */
1366int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1367{
1368 unsigned int depth = bprm->recursion_depth;
1369 int try,retval;
1370 struct linux_binfmt *fmt;
1371 pid_t old_pid;
1372
1373 retval = security_bprm_check(bprm);
1374 if (retval)
1375 return retval;
1376
1377 retval = audit_bprm(bprm);
1378 if (retval)
1379 return retval;
1380
1381 /* Need to fetch pid before load_binary changes it */
1382 rcu_read_lock();
1383 old_pid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1384 rcu_read_unlock();
1385
1386 retval = -ENOENT;
1387 for (try=0; try<2; try++) {
1388 read_lock(&binfmt_lock);
1389 list_for_each_entry(fmt, &formats, lh) {
1390 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1391 if (!fn)
1392 continue;
1393 if (!try_module_get(fmt->module))
1394 continue;
1395 read_unlock(&binfmt_lock);
1396 retval = fn(bprm, regs);
1397 /*
1398 * Restore the depth counter to its starting value
1399 * in this call, so we don't have to rely on every
1400 * load_binary function to restore it on return.
1401 */
1402 bprm->recursion_depth = depth;
1403 if (retval >= 0) {
1404 if (depth == 0)
1405 ptrace_event(PTRACE_EVENT_EXEC,
1406 old_pid);
1407 put_binfmt(fmt);
1408 allow_write_access(bprm->file);
1409 if (bprm->file)
1410 fput(bprm->file);
1411 bprm->file = NULL;
1412 current->did_exec = 1;
1413 proc_exec_connector(current);
1414 return retval;
1415 }
1416 read_lock(&binfmt_lock);
1417 put_binfmt(fmt);
1418 if (retval != -ENOEXEC || bprm->mm == NULL)
1419 break;
1420 if (!bprm->file) {
1421 read_unlock(&binfmt_lock);
1422 return retval;
1423 }
1424 }
1425 read_unlock(&binfmt_lock);
1426#ifdef CONFIG_MODULES
1427 if (retval != -ENOEXEC || bprm->mm == NULL) {
1428 break;
1429 } else {
1430#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1431 if (printable(bprm->buf[0]) &&
1432 printable(bprm->buf[1]) &&
1433 printable(bprm->buf[2]) &&
1434 printable(bprm->buf[3]))
1435 break; /* -ENOEXEC */
1436 if (try)
1437 break; /* -ENOEXEC */
1438 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1439 }
1440#else
1441 break;
1442#endif
1443 }
1444 return retval;
1445}
1446
1447EXPORT_SYMBOL(search_binary_handler);
1448
1449/*
1450 * sys_execve() executes a new program.
1451 */
1452static int do_execve_common(const char *filename,
1453 struct user_arg_ptr argv,
1454 struct user_arg_ptr envp,
1455 struct pt_regs *regs)
1456{
1457 struct linux_binprm *bprm;
1458 struct file *file;
1459 struct files_struct *displaced;
1460 bool clear_in_exec;
1461 int retval;
1462 const struct cred *cred = current_cred();
1463
1464 /*
1465 * We move the actual failure in case of RLIMIT_NPROC excess from
1466 * set*uid() to execve() because too many poorly written programs
1467 * don't check setuid() return code. Here we additionally recheck
1468 * whether NPROC limit is still exceeded.
1469 */
1470 if ((current->flags & PF_NPROC_EXCEEDED) &&
1471 atomic_read(&cred->user->processes) > rlimit(RLIMIT_NPROC)) {
1472 retval = -EAGAIN;
1473 goto out_ret;
1474 }
1475
1476 /* We're below the limit (still or again), so we don't want to make
1477 * further execve() calls fail. */
1478 current->flags &= ~PF_NPROC_EXCEEDED;
1479
1480 retval = unshare_files(&displaced);
1481 if (retval)
1482 goto out_ret;
1483
1484 retval = -ENOMEM;
1485 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1486 if (!bprm)
1487 goto out_files;
1488
1489 retval = prepare_bprm_creds(bprm);
1490 if (retval)
1491 goto out_free;
1492
1493 retval = check_unsafe_exec(bprm);
1494 if (retval < 0)
1495 goto out_free;
1496 clear_in_exec = retval;
1497 current->in_execve = 1;
1498
1499 file = open_exec(filename);
1500 retval = PTR_ERR(file);
1501 if (IS_ERR(file))
1502 goto out_unmark;
1503
1504 sched_exec();
1505
1506 bprm->file = file;
1507 bprm->filename = filename;
1508 bprm->interp = filename;
1509
1510 retval = bprm_mm_init(bprm);
1511 if (retval)
1512 goto out_file;
1513
1514 bprm->argc = count(argv, MAX_ARG_STRINGS);
1515 if ((retval = bprm->argc) < 0)
1516 goto out;
1517
1518 bprm->envc = count(envp, MAX_ARG_STRINGS);
1519 if ((retval = bprm->envc) < 0)
1520 goto out;
1521
1522 retval = prepare_binprm(bprm);
1523 if (retval < 0)
1524 goto out;
1525
1526 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1527 if (retval < 0)
1528 goto out;
1529
1530 bprm->exec = bprm->p;
1531 retval = copy_strings(bprm->envc, envp, bprm);
1532 if (retval < 0)
1533 goto out;
1534
1535 retval = copy_strings(bprm->argc, argv, bprm);
1536 if (retval < 0)
1537 goto out;
1538
1539 retval = search_binary_handler(bprm,regs);
1540 if (retval < 0)
1541 goto out;
1542
1543 /* execve succeeded */
1544 current->fs->in_exec = 0;
1545 current->in_execve = 0;
1546 acct_update_integrals(current);
1547 free_bprm(bprm);
1548 if (displaced)
1549 put_files_struct(displaced);
1550 return retval;
1551
1552out:
1553 if (bprm->mm) {
1554 acct_arg_size(bprm, 0);
1555 mmput(bprm->mm);
1556 }
1557
1558out_file:
1559 if (bprm->file) {
1560 allow_write_access(bprm->file);
1561 fput(bprm->file);
1562 }
1563
1564out_unmark:
1565 if (clear_in_exec)
1566 current->fs->in_exec = 0;
1567 current->in_execve = 0;
1568
1569out_free:
1570 free_bprm(bprm);
1571
1572out_files:
1573 if (displaced)
1574 reset_files_struct(displaced);
1575out_ret:
1576 return retval;
1577}
1578
1579int do_execve(const char *filename,
1580 const char __user *const __user *__argv,
1581 const char __user *const __user *__envp,
1582 struct pt_regs *regs)
1583{
1584 struct user_arg_ptr argv = { .ptr.native = __argv };
1585 struct user_arg_ptr envp = { .ptr.native = __envp };
1586 return do_execve_common(filename, argv, envp, regs);
1587}
1588
1589#ifdef CONFIG_COMPAT
1590int compat_do_execve(char *filename,
1591 compat_uptr_t __user *__argv,
1592 compat_uptr_t __user *__envp,
1593 struct pt_regs *regs)
1594{
1595 struct user_arg_ptr argv = {
1596 .is_compat = true,
1597 .ptr.compat = __argv,
1598 };
1599 struct user_arg_ptr envp = {
1600 .is_compat = true,
1601 .ptr.compat = __envp,
1602 };
1603 return do_execve_common(filename, argv, envp, regs);
1604}
1605#endif
1606
1607void set_binfmt(struct linux_binfmt *new)
1608{
1609 struct mm_struct *mm = current->mm;
1610
1611 if (mm->binfmt)
1612 module_put(mm->binfmt->module);
1613
1614 mm->binfmt = new;
1615 if (new)
1616 __module_get(new->module);
1617}
1618
1619EXPORT_SYMBOL(set_binfmt);
1620
1621static int expand_corename(struct core_name *cn)
1622{
1623 char *old_corename = cn->corename;
1624
1625 cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count);
1626 cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL);
1627
1628 if (!cn->corename) {
1629 kfree(old_corename);
1630 return -ENOMEM;
1631 }
1632
1633 return 0;
1634}
1635
1636static int cn_printf(struct core_name *cn, const char *fmt, ...)
1637{
1638 char *cur;
1639 int need;
1640 int ret;
1641 va_list arg;
1642
1643 va_start(arg, fmt);
1644 need = vsnprintf(NULL, 0, fmt, arg);
1645 va_end(arg);
1646
1647 if (likely(need < cn->size - cn->used - 1))
1648 goto out_printf;
1649
1650 ret = expand_corename(cn);
1651 if (ret)
1652 goto expand_fail;
1653
1654out_printf:
1655 cur = cn->corename + cn->used;
1656 va_start(arg, fmt);
1657 vsnprintf(cur, need + 1, fmt, arg);
1658 va_end(arg);
1659 cn->used += need;
1660 return 0;
1661
1662expand_fail:
1663 return ret;
1664}
1665
1666static void cn_escape(char *str)
1667{
1668 for (; *str; str++)
1669 if (*str == '/')
1670 *str = '!';
1671}
1672
1673static int cn_print_exe_file(struct core_name *cn)
1674{
1675 struct file *exe_file;
1676 char *pathbuf, *path;
1677 int ret;
1678
1679 exe_file = get_mm_exe_file(current->mm);
1680 if (!exe_file) {
1681 char *commstart = cn->corename + cn->used;
1682 ret = cn_printf(cn, "%s (path unknown)", current->comm);
1683 cn_escape(commstart);
1684 return ret;
1685 }
1686
1687 pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
1688 if (!pathbuf) {
1689 ret = -ENOMEM;
1690 goto put_exe_file;
1691 }
1692
1693 path = d_path(&exe_file->f_path, pathbuf, PATH_MAX);
1694 if (IS_ERR(path)) {
1695 ret = PTR_ERR(path);
1696 goto free_buf;
1697 }
1698
1699 cn_escape(path);
1700
1701 ret = cn_printf(cn, "%s", path);
1702
1703free_buf:
1704 kfree(pathbuf);
1705put_exe_file:
1706 fput(exe_file);
1707 return ret;
1708}
1709
1710/* format_corename will inspect the pattern parameter, and output a
1711 * name into corename, which must have space for at least
1712 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1713 */
1714static int format_corename(struct core_name *cn, long signr)
1715{
1716 const struct cred *cred = current_cred();
1717 const char *pat_ptr = core_pattern;
1718 int ispipe = (*pat_ptr == '|');
1719 int pid_in_pattern = 0;
1720 int err = 0;
1721
1722 cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count);
1723 cn->corename = kmalloc(cn->size, GFP_KERNEL);
1724 cn->used = 0;
1725
1726 if (!cn->corename)
1727 return -ENOMEM;
1728
1729 /* Repeat as long as we have more pattern to process and more output
1730 space */
1731 while (*pat_ptr) {
1732 if (*pat_ptr != '%') {
1733 if (*pat_ptr == 0)
1734 goto out;
1735 err = cn_printf(cn, "%c", *pat_ptr++);
1736 } else {
1737 switch (*++pat_ptr) {
1738 /* single % at the end, drop that */
1739 case 0:
1740 goto out;
1741 /* Double percent, output one percent */
1742 case '%':
1743 err = cn_printf(cn, "%c", '%');
1744 break;
1745 /* pid */
1746 case 'p':
1747 pid_in_pattern = 1;
1748 err = cn_printf(cn, "%d",
1749 task_tgid_vnr(current));
1750 break;
1751 /* uid */
1752 case 'u':
1753 err = cn_printf(cn, "%d", cred->uid);
1754 break;
1755 /* gid */
1756 case 'g':
1757 err = cn_printf(cn, "%d", cred->gid);
1758 break;
1759 /* signal that caused the coredump */
1760 case 's':
1761 err = cn_printf(cn, "%ld", signr);
1762 break;
1763 /* UNIX time of coredump */
1764 case 't': {
1765 struct timeval tv;
1766 do_gettimeofday(&tv);
1767 err = cn_printf(cn, "%lu", tv.tv_sec);
1768 break;
1769 }
1770 /* hostname */
1771 case 'h': {
1772 char *namestart = cn->corename + cn->used;
1773 down_read(&uts_sem);
1774 err = cn_printf(cn, "%s",
1775 utsname()->nodename);
1776 up_read(&uts_sem);
1777 cn_escape(namestart);
1778 break;
1779 }
1780 /* executable */
1781 case 'e': {
1782 char *commstart = cn->corename + cn->used;
1783 err = cn_printf(cn, "%s", current->comm);
1784 cn_escape(commstart);
1785 break;
1786 }
1787 case 'E':
1788 err = cn_print_exe_file(cn);
1789 break;
1790 /* core limit size */
1791 case 'c':
1792 err = cn_printf(cn, "%lu",
1793 rlimit(RLIMIT_CORE));
1794 break;
1795 default:
1796 break;
1797 }
1798 ++pat_ptr;
1799 }
1800
1801 if (err)
1802 return err;
1803 }
1804
1805 /* Backward compatibility with core_uses_pid:
1806 *
1807 * If core_pattern does not include a %p (as is the default)
1808 * and core_uses_pid is set, then .%pid will be appended to
1809 * the filename. Do not do this for piped commands. */
1810 if (!ispipe && !pid_in_pattern && core_uses_pid) {
1811 err = cn_printf(cn, ".%d", task_tgid_vnr(current));
1812 if (err)
1813 return err;
1814 }
1815out:
1816 return ispipe;
1817}
1818
1819static int zap_process(struct task_struct *start, int exit_code)
1820{
1821 struct task_struct *t;
1822 int nr = 0;
1823
1824 start->signal->flags = SIGNAL_GROUP_EXIT;
1825 start->signal->group_exit_code = exit_code;
1826 start->signal->group_stop_count = 0;
1827
1828 t = start;
1829 do {
1830 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1831 if (t != current && t->mm) {
1832 sigaddset(&t->pending.signal, SIGKILL);
1833 signal_wake_up(t, 1);
1834 nr++;
1835 }
1836 } while_each_thread(start, t);
1837
1838 return nr;
1839}
1840
1841static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1842 struct core_state *core_state, int exit_code)
1843{
1844 struct task_struct *g, *p;
1845 unsigned long flags;
1846 int nr = -EAGAIN;
1847
1848 spin_lock_irq(&tsk->sighand->siglock);
1849 if (!signal_group_exit(tsk->signal)) {
1850 mm->core_state = core_state;
1851 nr = zap_process(tsk, exit_code);
1852 }
1853 spin_unlock_irq(&tsk->sighand->siglock);
1854 if (unlikely(nr < 0))
1855 return nr;
1856
1857 if (atomic_read(&mm->mm_users) == nr + 1)
1858 goto done;
1859 /*
1860 * We should find and kill all tasks which use this mm, and we should
1861 * count them correctly into ->nr_threads. We don't take tasklist
1862 * lock, but this is safe wrt:
1863 *
1864 * fork:
1865 * None of sub-threads can fork after zap_process(leader). All
1866 * processes which were created before this point should be
1867 * visible to zap_threads() because copy_process() adds the new
1868 * process to the tail of init_task.tasks list, and lock/unlock
1869 * of ->siglock provides a memory barrier.
1870 *
1871 * do_exit:
1872 * The caller holds mm->mmap_sem. This means that the task which
1873 * uses this mm can't pass exit_mm(), so it can't exit or clear
1874 * its ->mm.
1875 *
1876 * de_thread:
1877 * It does list_replace_rcu(&leader->tasks, ¤t->tasks),
1878 * we must see either old or new leader, this does not matter.
1879 * However, it can change p->sighand, so lock_task_sighand(p)
1880 * must be used. Since p->mm != NULL and we hold ->mmap_sem
1881 * it can't fail.
1882 *
1883 * Note also that "g" can be the old leader with ->mm == NULL
1884 * and already unhashed and thus removed from ->thread_group.
1885 * This is OK, __unhash_process()->list_del_rcu() does not
1886 * clear the ->next pointer, we will find the new leader via
1887 * next_thread().
1888 */
1889 rcu_read_lock();
1890 for_each_process(g) {
1891 if (g == tsk->group_leader)
1892 continue;
1893 if (g->flags & PF_KTHREAD)
1894 continue;
1895 p = g;
1896 do {
1897 if (p->mm) {
1898 if (unlikely(p->mm == mm)) {
1899 lock_task_sighand(p, &flags);
1900 nr += zap_process(p, exit_code);
1901 unlock_task_sighand(p, &flags);
1902 }
1903 break;
1904 }
1905 } while_each_thread(g, p);
1906 }
1907 rcu_read_unlock();
1908done:
1909 atomic_set(&core_state->nr_threads, nr);
1910 return nr;
1911}
1912
1913static int coredump_wait(int exit_code, struct core_state *core_state)
1914{
1915 struct task_struct *tsk = current;
1916 struct mm_struct *mm = tsk->mm;
1917 struct completion *vfork_done;
1918 int core_waiters = -EBUSY;
1919
1920 init_completion(&core_state->startup);
1921 core_state->dumper.task = tsk;
1922 core_state->dumper.next = NULL;
1923
1924 down_write(&mm->mmap_sem);
1925 if (!mm->core_state)
1926 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1927 up_write(&mm->mmap_sem);
1928
1929 if (unlikely(core_waiters < 0))
1930 goto fail;
1931
1932 /*
1933 * Make sure nobody is waiting for us to release the VM,
1934 * otherwise we can deadlock when we wait on each other
1935 */
1936 vfork_done = tsk->vfork_done;
1937 if (vfork_done) {
1938 tsk->vfork_done = NULL;
1939 complete(vfork_done);
1940 }
1941
1942 if (core_waiters)
1943 wait_for_completion(&core_state->startup);
1944fail:
1945 return core_waiters;
1946}
1947
1948static void coredump_finish(struct mm_struct *mm)
1949{
1950 struct core_thread *curr, *next;
1951 struct task_struct *task;
1952
1953 next = mm->core_state->dumper.next;
1954 while ((curr = next) != NULL) {
1955 next = curr->next;
1956 task = curr->task;
1957 /*
1958 * see exit_mm(), curr->task must not see
1959 * ->task == NULL before we read ->next.
1960 */
1961 smp_mb();
1962 curr->task = NULL;
1963 wake_up_process(task);
1964 }
1965
1966 mm->core_state = NULL;
1967}
1968
1969/*
1970 * set_dumpable converts traditional three-value dumpable to two flags and
1971 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1972 * these bits are not changed atomically. So get_dumpable can observe the
1973 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1974 * return either old dumpable or new one by paying attention to the order of
1975 * modifying the bits.
1976 *
1977 * dumpable | mm->flags (binary)
1978 * old new | initial interim final
1979 * ---------+-----------------------
1980 * 0 1 | 00 01 01
1981 * 0 2 | 00 10(*) 11
1982 * 1 0 | 01 00 00
1983 * 1 2 | 01 11 11
1984 * 2 0 | 11 10(*) 00
1985 * 2 1 | 11 11 01
1986 *
1987 * (*) get_dumpable regards interim value of 10 as 11.
1988 */
1989void set_dumpable(struct mm_struct *mm, int value)
1990{
1991 switch (value) {
1992 case 0:
1993 clear_bit(MMF_DUMPABLE, &mm->flags);
1994 smp_wmb();
1995 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1996 break;
1997 case 1:
1998 set_bit(MMF_DUMPABLE, &mm->flags);
1999 smp_wmb();
2000 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
2001 break;
2002 case 2:
2003 set_bit(MMF_DUMP_SECURELY, &mm->flags);
2004 smp_wmb();
2005 set_bit(MMF_DUMPABLE, &mm->flags);
2006 break;
2007 }
2008}
2009
2010static int __get_dumpable(unsigned long mm_flags)
2011{
2012 int ret;
2013
2014 ret = mm_flags & MMF_DUMPABLE_MASK;
2015 return (ret >= 2) ? 2 : ret;
2016}
2017
2018int get_dumpable(struct mm_struct *mm)
2019{
2020 return __get_dumpable(mm->flags);
2021}
2022
2023static void wait_for_dump_helpers(struct file *file)
2024{
2025 struct pipe_inode_info *pipe;
2026
2027 pipe = file->f_path.dentry->d_inode->i_pipe;
2028
2029 pipe_lock(pipe);
2030 pipe->readers++;
2031 pipe->writers--;
2032
2033 while ((pipe->readers > 1) && (!signal_pending(current))) {
2034 wake_up_interruptible_sync(&pipe->wait);
2035 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
2036 pipe_wait(pipe);
2037 }
2038
2039 pipe->readers--;
2040 pipe->writers++;
2041 pipe_unlock(pipe);
2042
2043}
2044
2045
2046/*
2047 * umh_pipe_setup
2048 * helper function to customize the process used
2049 * to collect the core in userspace. Specifically
2050 * it sets up a pipe and installs it as fd 0 (stdin)
2051 * for the process. Returns 0 on success, or
2052 * PTR_ERR on failure.
2053 * Note that it also sets the core limit to 1. This
2054 * is a special value that we use to trap recursive
2055 * core dumps
2056 */
2057static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
2058{
2059 struct file *rp, *wp;
2060 struct fdtable *fdt;
2061 struct coredump_params *cp = (struct coredump_params *)info->data;
2062 struct files_struct *cf = current->files;
2063
2064 wp = create_write_pipe(0);
2065 if (IS_ERR(wp))
2066 return PTR_ERR(wp);
2067
2068 rp = create_read_pipe(wp, 0);
2069 if (IS_ERR(rp)) {
2070 free_write_pipe(wp);
2071 return PTR_ERR(rp);
2072 }
2073
2074 cp->file = wp;
2075
2076 sys_close(0);
2077 fd_install(0, rp);
2078 spin_lock(&cf->file_lock);
2079 fdt = files_fdtable(cf);
2080 FD_SET(0, fdt->open_fds);
2081 FD_CLR(0, fdt->close_on_exec);
2082 spin_unlock(&cf->file_lock);
2083
2084 /* and disallow core files too */
2085 current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
2086
2087 return 0;
2088}
2089
2090void do_coredump(long signr, int exit_code, struct pt_regs *regs)
2091{
2092 struct core_state core_state;
2093 struct core_name cn;
2094 struct mm_struct *mm = current->mm;
2095 struct linux_binfmt * binfmt;
2096 const struct cred *old_cred;
2097 struct cred *cred;
2098 int retval = 0;
2099 int flag = 0;
2100 int ispipe;
2101 static atomic_t core_dump_count = ATOMIC_INIT(0);
2102 struct coredump_params cprm = {
2103 .signr = signr,
2104 .regs = regs,
2105 .limit = rlimit(RLIMIT_CORE),
2106 /*
2107 * We must use the same mm->flags while dumping core to avoid
2108 * inconsistency of bit flags, since this flag is not protected
2109 * by any locks.
2110 */
2111 .mm_flags = mm->flags,
2112 };
2113
2114 audit_core_dumps(signr);
2115
2116 binfmt = mm->binfmt;
2117 if (!binfmt || !binfmt->core_dump)
2118 goto fail;
2119 if (!__get_dumpable(cprm.mm_flags))
2120 goto fail;
2121
2122 cred = prepare_creds();
2123 if (!cred)
2124 goto fail;
2125 /*
2126 * We cannot trust fsuid as being the "true" uid of the
2127 * process nor do we know its entire history. We only know it
2128 * was tainted so we dump it as root in mode 2.
2129 */
2130 if (__get_dumpable(cprm.mm_flags) == 2) {
2131 /* Setuid core dump mode */
2132 flag = O_EXCL; /* Stop rewrite attacks */
2133 cred->fsuid = 0; /* Dump root private */
2134 }
2135
2136 retval = coredump_wait(exit_code, &core_state);
2137 if (retval < 0)
2138 goto fail_creds;
2139
2140 old_cred = override_creds(cred);
2141
2142 /*
2143 * Clear any false indication of pending signals that might
2144 * be seen by the filesystem code called to write the core file.
2145 */
2146 clear_thread_flag(TIF_SIGPENDING);
2147
2148 ispipe = format_corename(&cn, signr);
2149
2150 if (ispipe) {
2151 int dump_count;
2152 char **helper_argv;
2153
2154 if (ispipe < 0) {
2155 printk(KERN_WARNING "format_corename failed\n");
2156 printk(KERN_WARNING "Aborting core\n");
2157 goto fail_corename;
2158 }
2159
2160 if (cprm.limit == 1) {
2161 /*
2162 * Normally core limits are irrelevant to pipes, since
2163 * we're not writing to the file system, but we use
2164 * cprm.limit of 1 here as a speacial value. Any
2165 * non-1 limit gets set to RLIM_INFINITY below, but
2166 * a limit of 0 skips the dump. This is a consistent
2167 * way to catch recursive crashes. We can still crash
2168 * if the core_pattern binary sets RLIM_CORE = !1
2169 * but it runs as root, and can do lots of stupid things
2170 * Note that we use task_tgid_vnr here to grab the pid
2171 * of the process group leader. That way we get the
2172 * right pid if a thread in a multi-threaded
2173 * core_pattern process dies.
2174 */
2175 printk(KERN_WARNING
2176 "Process %d(%s) has RLIMIT_CORE set to 1\n",
2177 task_tgid_vnr(current), current->comm);
2178 printk(KERN_WARNING "Aborting core\n");
2179 goto fail_unlock;
2180 }
2181 cprm.limit = RLIM_INFINITY;
2182
2183 dump_count = atomic_inc_return(&core_dump_count);
2184 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
2185 printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
2186 task_tgid_vnr(current), current->comm);
2187 printk(KERN_WARNING "Skipping core dump\n");
2188 goto fail_dropcount;
2189 }
2190
2191 helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL);
2192 if (!helper_argv) {
2193 printk(KERN_WARNING "%s failed to allocate memory\n",
2194 __func__);
2195 goto fail_dropcount;
2196 }
2197
2198 retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
2199 NULL, UMH_WAIT_EXEC, umh_pipe_setup,
2200 NULL, &cprm);
2201 argv_free(helper_argv);
2202 if (retval) {
2203 printk(KERN_INFO "Core dump to %s pipe failed\n",
2204 cn.corename);
2205 goto close_fail;
2206 }
2207 } else {
2208 struct inode *inode;
2209
2210 if (cprm.limit < binfmt->min_coredump)
2211 goto fail_unlock;
2212
2213 cprm.file = filp_open(cn.corename,
2214 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
2215 0600);
2216 if (IS_ERR(cprm.file))
2217 goto fail_unlock;
2218
2219 inode = cprm.file->f_path.dentry->d_inode;
2220 if (inode->i_nlink > 1)
2221 goto close_fail;
2222 if (d_unhashed(cprm.file->f_path.dentry))
2223 goto close_fail;
2224 /*
2225 * AK: actually i see no reason to not allow this for named
2226 * pipes etc, but keep the previous behaviour for now.
2227 */
2228 if (!S_ISREG(inode->i_mode))
2229 goto close_fail;
2230 /*
2231 * Dont allow local users get cute and trick others to coredump
2232 * into their pre-created files.
2233 */
2234 if (inode->i_uid != current_fsuid())
2235 goto close_fail;
2236 if (!cprm.file->f_op || !cprm.file->f_op->write)
2237 goto close_fail;
2238 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
2239 goto close_fail;
2240 }
2241
2242 retval = binfmt->core_dump(&cprm);
2243 if (retval)
2244 current->signal->group_exit_code |= 0x80;
2245
2246 if (ispipe && core_pipe_limit)
2247 wait_for_dump_helpers(cprm.file);
2248close_fail:
2249 if (cprm.file)
2250 filp_close(cprm.file, NULL);
2251fail_dropcount:
2252 if (ispipe)
2253 atomic_dec(&core_dump_count);
2254fail_unlock:
2255 kfree(cn.corename);
2256fail_corename:
2257 coredump_finish(mm);
2258 revert_creds(old_cred);
2259fail_creds:
2260 put_cred(cred);
2261fail:
2262 return;
2263}
2264
2265/*
2266 * Core dumping helper functions. These are the only things you should
2267 * do on a core-file: use only these functions to write out all the
2268 * necessary info.
2269 */
2270int dump_write(struct file *file, const void *addr, int nr)
2271{
2272 return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr;
2273}
2274EXPORT_SYMBOL(dump_write);
2275
2276int dump_seek(struct file *file, loff_t off)
2277{
2278 int ret = 1;
2279
2280 if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
2281 if (file->f_op->llseek(file, off, SEEK_CUR) < 0)
2282 return 0;
2283 } else {
2284 char *buf = (char *)get_zeroed_page(GFP_KERNEL);
2285
2286 if (!buf)
2287 return 0;
2288 while (off > 0) {
2289 unsigned long n = off;
2290
2291 if (n > PAGE_SIZE)
2292 n = PAGE_SIZE;
2293 if (!dump_write(file, buf, n)) {
2294 ret = 0;
2295 break;
2296 }
2297 off -= n;
2298 }
2299 free_page((unsigned long)buf);
2300 }
2301 return ret;
2302}
2303EXPORT_SYMBOL(dump_seek);