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
  60#include <asm/uaccess.h>
  61#include <asm/mmu_context.h>
  62#include <asm/tlb.h>
 
  63
  64#include <trace/events/task.h>
  65#include "internal.h"
  66
  67#include <trace/events/sched.h>
  68
 
 
 
  69int suid_dumpable = 0;
  70
 
 
 
 
 
 
 
 
  71static LIST_HEAD(formats);
  72static DEFINE_RWLOCK(binfmt_lock);
  73
  74void __register_binfmt(struct linux_binfmt * fmt, int insert)
  75{
  76	BUG_ON(!fmt);
  77	if (WARN_ON(!fmt->load_binary))
  78		return;
  79	write_lock(&binfmt_lock);
  80	insert ? list_add(&fmt->lh, &formats) :
  81		 list_add_tail(&fmt->lh, &formats);
  82	write_unlock(&binfmt_lock);
  83}
  84
  85EXPORT_SYMBOL(__register_binfmt);
  86
  87void unregister_binfmt(struct linux_binfmt * fmt)
  88{
  89	write_lock(&binfmt_lock);
  90	list_del(&fmt->lh);
  91	write_unlock(&binfmt_lock);
  92}
  93
  94EXPORT_SYMBOL(unregister_binfmt);
  95
  96static inline void put_binfmt(struct linux_binfmt * fmt)
  97{
  98	module_put(fmt->module);
  99}
 100
 101#ifdef CONFIG_USELIB
 102/*
 103 * Note that a shared library must be both readable and executable due to
 104 * security reasons.
 105 *
 106 * Also note that we take the address to load from from the file itself.
 107 */
 108SYSCALL_DEFINE1(uselib, const char __user *, library)
 109{
 110	struct linux_binfmt *fmt;
 111	struct file *file;
 112	struct filename *tmp = getname(library);
 113	int error = PTR_ERR(tmp);
 114	static const struct open_flags uselib_flags = {
 115		.open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 116		.acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN,
 117		.intent = LOOKUP_OPEN,
 118		.lookup_flags = LOOKUP_FOLLOW,
 119	};
 120
 121	if (IS_ERR(tmp))
 122		goto out;
 123
 124	file = do_filp_open(AT_FDCWD, tmp, &uselib_flags);
 125	putname(tmp);
 126	error = PTR_ERR(file);
 127	if (IS_ERR(file))
 128		goto out;
 129
 130	error = -EINVAL;
 131	if (!S_ISREG(file_inode(file)->i_mode))
 132		goto exit;
 133
 134	error = -EACCES;
 135	if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
 136		goto exit;
 137
 138	fsnotify_open(file);
 139
 140	error = -ENOEXEC;
 
 
 141
 142	read_lock(&binfmt_lock);
 143	list_for_each_entry(fmt, &formats, lh) {
 144		if (!fmt->load_shlib)
 145			continue;
 146		if (!try_module_get(fmt->module))
 147			continue;
 148		read_unlock(&binfmt_lock);
 149		error = fmt->load_shlib(file);
 150		read_lock(&binfmt_lock);
 151		put_binfmt(fmt);
 152		if (error != -ENOEXEC)
 153			break;
 
 
 
 
 
 
 
 
 
 
 154	}
 155	read_unlock(&binfmt_lock);
 156exit:
 157	fput(file);
 158out:
 159  	return error;
 160}
 161#endif /* #ifdef CONFIG_USELIB */
 162
 163#ifdef CONFIG_MMU
 164/*
 165 * The nascent bprm->mm is not visible until exec_mmap() but it can
 166 * use a lot of memory, account these pages in current->mm temporary
 167 * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
 168 * change the counter back via acct_arg_size(0).
 169 */
 170static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 171{
 172	struct mm_struct *mm = current->mm;
 173	long diff = (long)(pages - bprm->vma_pages);
 174
 175	if (!mm || !diff)
 176		return;
 177
 178	bprm->vma_pages = pages;
 179	add_mm_counter(mm, MM_ANONPAGES, diff);
 180}
 181
 182static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 183		int write)
 184{
 185	struct page *page;
 186	int ret;
 187
 188#ifdef CONFIG_STACK_GROWSUP
 189	if (write) {
 190		ret = expand_downwards(bprm->vma, pos);
 191		if (ret < 0)
 192			return NULL;
 193	}
 194#endif
 195	ret = get_user_pages(current, bprm->mm, pos,
 196			1, write, 1, &page, NULL);
 197	if (ret <= 0)
 198		return NULL;
 199
 200	if (write) {
 201		unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
 202		struct rlimit *rlim;
 203
 204		acct_arg_size(bprm, size / PAGE_SIZE);
 205
 206		/*
 207		 * We've historically supported up to 32 pages (ARG_MAX)
 208		 * of argument strings even with small stacks
 209		 */
 210		if (size <= ARG_MAX)
 211			return page;
 212
 213		/*
 214		 * Limit to 1/4-th the stack size for the argv+env strings.
 215		 * This ensures that:
 216		 *  - the remaining binfmt code will not run out of stack space,
 217		 *  - the program will have a reasonable amount of stack left
 218		 *    to work from.
 219		 */
 220		rlim = current->signal->rlim;
 221		if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
 222			put_page(page);
 223			return NULL;
 224		}
 225	}
 226
 227	return page;
 228}
 229
 230static void put_arg_page(struct page *page)
 231{
 232	put_page(page);
 233}
 234
 235static void free_arg_page(struct linux_binprm *bprm, int i)
 236{
 237}
 238
 239static void free_arg_pages(struct linux_binprm *bprm)
 240{
 241}
 242
 243static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 244		struct page *page)
 245{
 246	flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 247}
 248
 249static int __bprm_mm_init(struct linux_binprm *bprm)
 250{
 251	int err;
 252	struct vm_area_struct *vma = NULL;
 253	struct mm_struct *mm = bprm->mm;
 254
 255	bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
 256	if (!vma)
 257		return -ENOMEM;
 258
 259	down_write(&mm->mmap_sem);
 260	vma->vm_mm = mm;
 261
 262	/*
 263	 * Place the stack at the largest stack address the architecture
 264	 * supports. Later, we'll move this to an appropriate place. We don't
 265	 * use STACK_TOP because that can depend on attributes which aren't
 266	 * configured yet.
 267	 */
 268	BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
 269	vma->vm_end = STACK_TOP_MAX;
 270	vma->vm_start = vma->vm_end - PAGE_SIZE;
 271	vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
 272	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 273	INIT_LIST_HEAD(&vma->anon_vma_chain);
 274
 275	err = insert_vm_struct(mm, vma);
 276	if (err)
 277		goto err;
 278
 279	mm->stack_vm = mm->total_vm = 1;
 280	up_write(&mm->mmap_sem);
 281	bprm->p = vma->vm_end - sizeof(void *);
 282	return 0;
 283err:
 284	up_write(&mm->mmap_sem);
 285	bprm->vma = NULL;
 286	kmem_cache_free(vm_area_cachep, vma);
 287	return err;
 288}
 289
 290static bool valid_arg_len(struct linux_binprm *bprm, long len)
 291{
 292	return len <= MAX_ARG_STRLEN;
 293}
 294
 295#else
 296
 297static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 298{
 299}
 300
 301static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 302		int write)
 303{
 304	struct page *page;
 305
 306	page = bprm->page[pos / PAGE_SIZE];
 307	if (!page && write) {
 308		page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 309		if (!page)
 310			return NULL;
 311		bprm->page[pos / PAGE_SIZE] = page;
 312	}
 313
 314	return page;
 315}
 316
 317static void put_arg_page(struct page *page)
 318{
 319}
 320
 321static void free_arg_page(struct linux_binprm *bprm, int i)
 322{
 323	if (bprm->page[i]) {
 324		__free_page(bprm->page[i]);
 325		bprm->page[i] = NULL;
 326	}
 327}
 328
 329static void free_arg_pages(struct linux_binprm *bprm)
 330{
 331	int i;
 332
 333	for (i = 0; i < MAX_ARG_PAGES; i++)
 334		free_arg_page(bprm, i);
 335}
 336
 337static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 338		struct page *page)
 339{
 340}
 341
 342static int __bprm_mm_init(struct linux_binprm *bprm)
 343{
 344	bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 345	return 0;
 346}
 347
 348static bool valid_arg_len(struct linux_binprm *bprm, long len)
 349{
 350	return len <= bprm->p;
 351}
 352
 353#endif /* CONFIG_MMU */
 354
 355/*
 356 * Create a new mm_struct and populate it with a temporary stack
 357 * vm_area_struct.  We don't have enough context at this point to set the stack
 358 * flags, permissions, and offset, so we use temporary values.  We'll update
 359 * them later in setup_arg_pages().
 360 */
 361static int bprm_mm_init(struct linux_binprm *bprm)
 362{
 363	int err;
 364	struct mm_struct *mm = NULL;
 365
 366	bprm->mm = mm = mm_alloc();
 367	err = -ENOMEM;
 368	if (!mm)
 369		goto err;
 370
 371	err = init_new_context(current, mm);
 372	if (err)
 373		goto err;
 374
 375	err = __bprm_mm_init(bprm);
 376	if (err)
 377		goto err;
 378
 379	return 0;
 380
 381err:
 382	if (mm) {
 383		bprm->mm = NULL;
 384		mmdrop(mm);
 385	}
 386
 387	return err;
 388}
 389
 390struct user_arg_ptr {
 391#ifdef CONFIG_COMPAT
 392	bool is_compat;
 393#endif
 394	union {
 395		const char __user *const __user *native;
 396#ifdef CONFIG_COMPAT
 397		const compat_uptr_t __user *compat;
 398#endif
 399	} ptr;
 400};
 401
 402static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
 403{
 404	const char __user *native;
 405
 406#ifdef CONFIG_COMPAT
 407	if (unlikely(argv.is_compat)) {
 408		compat_uptr_t compat;
 409
 410		if (get_user(compat, argv.ptr.compat + nr))
 411			return ERR_PTR(-EFAULT);
 412
 413		return compat_ptr(compat);
 414	}
 415#endif
 416
 417	if (get_user(native, argv.ptr.native + nr))
 418		return ERR_PTR(-EFAULT);
 419
 420	return native;
 421}
 422
 423/*
 424 * count() counts the number of strings in array ARGV.
 425 */
 426static int count(struct user_arg_ptr argv, int max)
 427{
 428	int i = 0;
 429
 430	if (argv.ptr.native != NULL) {
 431		for (;;) {
 432			const char __user *p = get_user_arg_ptr(argv, i);
 433
 434			if (!p)
 435				break;
 436
 437			if (IS_ERR(p))
 438				return -EFAULT;
 439
 440			if (i >= max)
 441				return -E2BIG;
 442			++i;
 443
 444			if (fatal_signal_pending(current))
 445				return -ERESTARTNOHAND;
 446			cond_resched();
 447		}
 448	}
 449	return i;
 450}
 451
 452/*
 453 * 'copy_strings()' copies argument/environment strings from the old
 454 * processes's memory to the new process's stack.  The call to get_user_pages()
 455 * ensures the destination page is created and not swapped out.
 456 */
 457static int copy_strings(int argc, struct user_arg_ptr argv,
 458			struct linux_binprm *bprm)
 459{
 460	struct page *kmapped_page = NULL;
 461	char *kaddr = NULL;
 462	unsigned long kpos = 0;
 463	int ret;
 464
 465	while (argc-- > 0) {
 466		const char __user *str;
 467		int len;
 468		unsigned long pos;
 469
 470		ret = -EFAULT;
 471		str = get_user_arg_ptr(argv, argc);
 472		if (IS_ERR(str))
 473			goto out;
 474
 475		len = strnlen_user(str, MAX_ARG_STRLEN);
 476		if (!len)
 477			goto out;
 478
 479		ret = -E2BIG;
 480		if (!valid_arg_len(bprm, len))
 481			goto out;
 482
 483		/* We're going to work our way backwords. */
 484		pos = bprm->p;
 485		str += len;
 486		bprm->p -= len;
 487
 488		while (len > 0) {
 489			int offset, bytes_to_copy;
 490
 491			if (fatal_signal_pending(current)) {
 492				ret = -ERESTARTNOHAND;
 493				goto out;
 494			}
 495			cond_resched();
 496
 497			offset = pos % PAGE_SIZE;
 498			if (offset == 0)
 499				offset = PAGE_SIZE;
 500
 501			bytes_to_copy = offset;
 502			if (bytes_to_copy > len)
 503				bytes_to_copy = len;
 504
 505			offset -= bytes_to_copy;
 506			pos -= bytes_to_copy;
 507			str -= bytes_to_copy;
 508			len -= bytes_to_copy;
 509
 510			if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 511				struct page *page;
 512
 513				page = get_arg_page(bprm, pos, 1);
 514				if (!page) {
 515					ret = -E2BIG;
 516					goto out;
 517				}
 518
 519				if (kmapped_page) {
 520					flush_kernel_dcache_page(kmapped_page);
 521					kunmap(kmapped_page);
 522					put_arg_page(kmapped_page);
 523				}
 524				kmapped_page = page;
 525				kaddr = kmap(kmapped_page);
 526				kpos = pos & PAGE_MASK;
 527				flush_arg_page(bprm, kpos, kmapped_page);
 528			}
 529			if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 530				ret = -EFAULT;
 531				goto out;
 532			}
 533		}
 534	}
 535	ret = 0;
 536out:
 537	if (kmapped_page) {
 538		flush_kernel_dcache_page(kmapped_page);
 539		kunmap(kmapped_page);
 540		put_arg_page(kmapped_page);
 541	}
 542	return ret;
 543}
 544
 545/*
 546 * Like copy_strings, but get argv and its values from kernel memory.
 547 */
 548int copy_strings_kernel(int argc, const char *const *__argv,
 549			struct linux_binprm *bprm)
 550{
 551	int r;
 552	mm_segment_t oldfs = get_fs();
 553	struct user_arg_ptr argv = {
 554		.ptr.native = (const char __user *const  __user *)__argv,
 555	};
 556
 557	set_fs(KERNEL_DS);
 558	r = copy_strings(argc, argv, bprm);
 559	set_fs(oldfs);
 560
 561	return r;
 562}
 563EXPORT_SYMBOL(copy_strings_kernel);
 564
 565#ifdef CONFIG_MMU
 566
 567/*
 568 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 569 * the binfmt code determines where the new stack should reside, we shift it to
 570 * its final location.  The process proceeds as follows:
 571 *
 572 * 1) Use shift to calculate the new vma endpoints.
 573 * 2) Extend vma to cover both the old and new ranges.  This ensures the
 574 *    arguments passed to subsequent functions are consistent.
 575 * 3) Move vma's page tables to the new range.
 576 * 4) Free up any cleared pgd range.
 577 * 5) Shrink the vma to cover only the new range.
 578 */
 579static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 580{
 581	struct mm_struct *mm = vma->vm_mm;
 582	unsigned long old_start = vma->vm_start;
 583	unsigned long old_end = vma->vm_end;
 584	unsigned long length = old_end - old_start;
 585	unsigned long new_start = old_start - shift;
 586	unsigned long new_end = old_end - shift;
 587	struct mmu_gather tlb;
 588
 589	BUG_ON(new_start > new_end);
 590
 591	/*
 592	 * ensure there are no vmas between where we want to go
 593	 * and where we are
 594	 */
 595	if (vma != find_vma(mm, new_start))
 596		return -EFAULT;
 597
 598	/*
 599	 * cover the whole range: [new_start, old_end)
 600	 */
 601	if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
 602		return -ENOMEM;
 603
 604	/*
 605	 * move the page tables downwards, on failure we rely on
 606	 * process cleanup to remove whatever mess we made.
 607	 */
 608	if (length != move_page_tables(vma, old_start,
 609				       vma, new_start, length, false))
 610		return -ENOMEM;
 611
 612	lru_add_drain();
 613	tlb_gather_mmu(&tlb, mm, old_start, old_end);
 614	if (new_end > old_start) {
 615		/*
 616		 * when the old and new regions overlap clear from new_end.
 617		 */
 618		free_pgd_range(&tlb, new_end, old_end, new_end,
 619			vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
 620	} else {
 621		/*
 622		 * otherwise, clean from old_start; this is done to not touch
 623		 * the address space in [new_end, old_start) some architectures
 624		 * have constraints on va-space that make this illegal (IA64) -
 625		 * for the others its just a little faster.
 626		 */
 627		free_pgd_range(&tlb, old_start, old_end, new_end,
 628			vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
 629	}
 630	tlb_finish_mmu(&tlb, old_start, old_end);
 631
 632	/*
 633	 * Shrink the vma to just the new range.  Always succeeds.
 634	 */
 635	vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 636
 637	return 0;
 638}
 639
 640/*
 641 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 642 * the stack is optionally relocated, and some extra space is added.
 643 */
 644int setup_arg_pages(struct linux_binprm *bprm,
 645		    unsigned long stack_top,
 646		    int executable_stack)
 647{
 648	unsigned long ret;
 649	unsigned long stack_shift;
 650	struct mm_struct *mm = current->mm;
 651	struct vm_area_struct *vma = bprm->vma;
 652	struct vm_area_struct *prev = NULL;
 653	unsigned long vm_flags;
 654	unsigned long stack_base;
 655	unsigned long stack_size;
 656	unsigned long stack_expand;
 657	unsigned long rlim_stack;
 658
 659#ifdef CONFIG_STACK_GROWSUP
 660	/* Limit stack size */
 661	stack_base = rlimit_max(RLIMIT_STACK);
 662	if (stack_base > STACK_SIZE_MAX)
 663		stack_base = STACK_SIZE_MAX;
 664
 665	/* Make sure we didn't let the argument array grow too large. */
 666	if (vma->vm_end - vma->vm_start > stack_base)
 667		return -ENOMEM;
 668
 669	stack_base = PAGE_ALIGN(stack_top - stack_base);
 670
 671	stack_shift = vma->vm_start - stack_base;
 672	mm->arg_start = bprm->p - stack_shift;
 673	bprm->p = vma->vm_end - stack_shift;
 674#else
 675	stack_top = arch_align_stack(stack_top);
 676	stack_top = PAGE_ALIGN(stack_top);
 677
 678	if (unlikely(stack_top < mmap_min_addr) ||
 679	    unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
 680		return -ENOMEM;
 681
 682	stack_shift = vma->vm_end - stack_top;
 683
 684	bprm->p -= stack_shift;
 685	mm->arg_start = bprm->p;
 686#endif
 687
 688	if (bprm->loader)
 689		bprm->loader -= stack_shift;
 690	bprm->exec -= stack_shift;
 691
 692	down_write(&mm->mmap_sem);
 693	vm_flags = VM_STACK_FLAGS;
 694
 695	/*
 696	 * Adjust stack execute permissions; explicitly enable for
 697	 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 698	 * (arch default) otherwise.
 699	 */
 700	if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 701		vm_flags |= VM_EXEC;
 702	else if (executable_stack == EXSTACK_DISABLE_X)
 703		vm_flags &= ~VM_EXEC;
 704	vm_flags |= mm->def_flags;
 705	vm_flags |= VM_STACK_INCOMPLETE_SETUP;
 706
 707	ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 708			vm_flags);
 709	if (ret)
 710		goto out_unlock;
 711	BUG_ON(prev != vma);
 712
 713	/* Move stack pages down in memory. */
 714	if (stack_shift) {
 715		ret = shift_arg_pages(vma, stack_shift);
 716		if (ret)
 717			goto out_unlock;
 718	}
 719
 720	/* mprotect_fixup is overkill to remove the temporary stack flags */
 721	vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
 722
 723	stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
 724	stack_size = vma->vm_end - vma->vm_start;
 725	/*
 726	 * Align this down to a page boundary as expand_stack
 727	 * will align it up.
 728	 */
 729	rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
 730#ifdef CONFIG_STACK_GROWSUP
 731	if (stack_size + stack_expand > rlim_stack)
 732		stack_base = vma->vm_start + rlim_stack;
 733	else
 734		stack_base = vma->vm_end + stack_expand;
 735#else
 736	if (stack_size + stack_expand > rlim_stack)
 737		stack_base = vma->vm_end - rlim_stack;
 738	else
 739		stack_base = vma->vm_start - stack_expand;
 740#endif
 741	current->mm->start_stack = bprm->p;
 742	ret = expand_stack(vma, stack_base);
 743	if (ret)
 744		ret = -EFAULT;
 745
 746out_unlock:
 747	up_write(&mm->mmap_sem);
 748	return ret;
 749}
 750EXPORT_SYMBOL(setup_arg_pages);
 751
 752#endif /* CONFIG_MMU */
 753
 754static struct file *do_open_exec(struct filename *name)
 755{
 756	struct file *file;
 757	int err;
 758	static const struct open_flags open_exec_flags = {
 759		.open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 760		.acc_mode = MAY_EXEC | MAY_OPEN,
 761		.intent = LOOKUP_OPEN,
 762		.lookup_flags = LOOKUP_FOLLOW,
 763	};
 764
 765	file = do_filp_open(AT_FDCWD, name, &open_exec_flags);
 766	if (IS_ERR(file))
 767		goto out;
 768
 769	err = -EACCES;
 770	if (!S_ISREG(file_inode(file)->i_mode))
 771		goto exit;
 772
 773	if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
 774		goto exit;
 775
 776	fsnotify_open(file);
 777
 778	err = deny_write_access(file);
 779	if (err)
 780		goto exit;
 781
 782out:
 783	return file;
 784
 785exit:
 786	fput(file);
 787	return ERR_PTR(err);
 788}
 789
 790struct file *open_exec(const char *name)
 791{
 792	struct filename tmp = { .name = name };
 793	return do_open_exec(&tmp);
 794}
 795EXPORT_SYMBOL(open_exec);
 796
 797int kernel_read(struct file *file, loff_t offset,
 798		char *addr, unsigned long count)
 799{
 800	mm_segment_t old_fs;
 801	loff_t pos = offset;
 802	int result;
 803
 804	old_fs = get_fs();
 805	set_fs(get_ds());
 806	/* The cast to a user pointer is valid due to the set_fs() */
 807	result = vfs_read(file, (void __user *)addr, count, &pos);
 808	set_fs(old_fs);
 809	return result;
 810}
 811
 812EXPORT_SYMBOL(kernel_read);
 813
 814ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
 815{
 816	ssize_t res = vfs_read(file, (void __user *)addr, len, &pos);
 817	if (res > 0)
 818		flush_icache_range(addr, addr + len);
 819	return res;
 820}
 821EXPORT_SYMBOL(read_code);
 822
 823static int exec_mmap(struct mm_struct *mm)
 824{
 825	struct task_struct *tsk;
 826	struct mm_struct *old_mm, *active_mm;
 827
 828	/* Notify parent that we're no longer interested in the old VM */
 829	tsk = current;
 830	old_mm = current->mm;
 831	mm_release(tsk, old_mm);
 832
 833	if (old_mm) {
 834		sync_mm_rss(old_mm);
 835		/*
 836		 * Make sure that if there is a core dump in progress
 837		 * for the old mm, we get out and die instead of going
 838		 * through with the exec.  We must hold mmap_sem around
 839		 * checking core_state and changing tsk->mm.
 840		 */
 841		down_read(&old_mm->mmap_sem);
 842		if (unlikely(old_mm->core_state)) {
 843			up_read(&old_mm->mmap_sem);
 844			return -EINTR;
 845		}
 846	}
 847	task_lock(tsk);
 848	active_mm = tsk->active_mm;
 849	tsk->mm = mm;
 850	tsk->active_mm = mm;
 851	activate_mm(active_mm, mm);
 852	tsk->mm->vmacache_seqnum = 0;
 853	vmacache_flush(tsk);
 854	task_unlock(tsk);
 
 855	if (old_mm) {
 856		up_read(&old_mm->mmap_sem);
 857		BUG_ON(active_mm != old_mm);
 858		setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
 859		mm_update_next_owner(old_mm);
 860		mmput(old_mm);
 861		return 0;
 862	}
 863	mmdrop(active_mm);
 864	return 0;
 865}
 866
 867/*
 868 * This function makes sure the current process has its own signal table,
 869 * so that flush_signal_handlers can later reset the handlers without
 870 * disturbing other processes.  (Other processes might share the signal
 871 * table via the CLONE_SIGHAND option to clone().)
 872 */
 873static int de_thread(struct task_struct *tsk)
 874{
 875	struct signal_struct *sig = tsk->signal;
 876	struct sighand_struct *oldsighand = tsk->sighand;
 877	spinlock_t *lock = &oldsighand->siglock;
 878
 879	if (thread_group_empty(tsk))
 880		goto no_thread_group;
 881
 882	/*
 883	 * Kill all other threads in the thread group.
 884	 */
 885	spin_lock_irq(lock);
 886	if (signal_group_exit(sig)) {
 887		/*
 888		 * Another group action in progress, just
 889		 * return so that the signal is processed.
 890		 */
 891		spin_unlock_irq(lock);
 892		return -EAGAIN;
 893	}
 894
 895	sig->group_exit_task = tsk;
 896	sig->notify_count = zap_other_threads(tsk);
 897	if (!thread_group_leader(tsk))
 898		sig->notify_count--;
 899
 900	while (sig->notify_count) {
 901		__set_current_state(TASK_KILLABLE);
 902		spin_unlock_irq(lock);
 903		schedule();
 904		if (unlikely(__fatal_signal_pending(tsk)))
 905			goto killed;
 906		spin_lock_irq(lock);
 907	}
 908	spin_unlock_irq(lock);
 909
 910	/*
 911	 * At this point all other threads have exited, all we have to
 912	 * do is to wait for the thread group leader to become inactive,
 913	 * and to assume its PID:
 914	 */
 915	if (!thread_group_leader(tsk)) {
 916		struct task_struct *leader = tsk->group_leader;
 917
 918		sig->notify_count = -1;	/* for exit_notify() */
 919		for (;;) {
 920			threadgroup_change_begin(tsk);
 921			write_lock_irq(&tasklist_lock);
 922			if (likely(leader->exit_state))
 923				break;
 924			__set_current_state(TASK_KILLABLE);
 925			write_unlock_irq(&tasklist_lock);
 926			threadgroup_change_end(tsk);
 927			schedule();
 928			if (unlikely(__fatal_signal_pending(tsk)))
 929				goto killed;
 930		}
 931
 932		/*
 933		 * The only record we have of the real-time age of a
 934		 * process, regardless of execs it's done, is start_time.
 935		 * All the past CPU time is accumulated in signal_struct
 936		 * from sister threads now dead.  But in this non-leader
 937		 * exec, nothing survives from the original leader thread,
 938		 * whose birth marks the true age of this process now.
 939		 * When we take on its identity by switching to its PID, we
 940		 * also take its birthdate (always earlier than our own).
 941		 */
 942		tsk->start_time = leader->start_time;
 943		tsk->real_start_time = leader->real_start_time;
 944
 945		BUG_ON(!same_thread_group(leader, tsk));
 946		BUG_ON(has_group_leader_pid(tsk));
 947		/*
 948		 * An exec() starts a new thread group with the
 949		 * TGID of the previous thread group. Rehash the
 950		 * two threads with a switched PID, and release
 951		 * the former thread group leader:
 952		 */
 953
 954		/* Become a process group leader with the old leader's pid.
 955		 * The old leader becomes a thread of the this thread group.
 956		 * Note: The old leader also uses this pid until release_task
 957		 *       is called.  Odd but simple and correct.
 958		 */
 
 959		tsk->pid = leader->pid;
 960		change_pid(tsk, PIDTYPE_PID, task_pid(leader));
 961		transfer_pid(leader, tsk, PIDTYPE_PGID);
 962		transfer_pid(leader, tsk, PIDTYPE_SID);
 963
 964		list_replace_rcu(&leader->tasks, &tsk->tasks);
 965		list_replace_init(&leader->sibling, &tsk->sibling);
 966
 967		tsk->group_leader = tsk;
 968		leader->group_leader = tsk;
 969
 970		tsk->exit_signal = SIGCHLD;
 971		leader->exit_signal = -1;
 972
 973		BUG_ON(leader->exit_state != EXIT_ZOMBIE);
 974		leader->exit_state = EXIT_DEAD;
 975
 976		/*
 977		 * We are going to release_task()->ptrace_unlink() silently,
 978		 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
 979		 * the tracer wont't block again waiting for this thread.
 980		 */
 981		if (unlikely(leader->ptrace))
 982			__wake_up_parent(leader, leader->parent);
 983		write_unlock_irq(&tasklist_lock);
 984		threadgroup_change_end(tsk);
 985
 986		release_task(leader);
 987	}
 988
 989	sig->group_exit_task = NULL;
 990	sig->notify_count = 0;
 991
 992no_thread_group:
 993	/* we have changed execution domain */
 994	tsk->exit_signal = SIGCHLD;
 995
 996	exit_itimers(sig);
 997	flush_itimer_signals();
 998
 999	if (atomic_read(&oldsighand->count) != 1) {
1000		struct sighand_struct *newsighand;
1001		/*
1002		 * This ->sighand is shared with the CLONE_SIGHAND
1003		 * but not CLONE_THREAD task, switch to the new one.
1004		 */
1005		newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1006		if (!newsighand)
1007			return -ENOMEM;
1008
1009		atomic_set(&newsighand->count, 1);
1010		memcpy(newsighand->action, oldsighand->action,
1011		       sizeof(newsighand->action));
1012
1013		write_lock_irq(&tasklist_lock);
1014		spin_lock(&oldsighand->siglock);
1015		rcu_assign_pointer(tsk->sighand, newsighand);
1016		spin_unlock(&oldsighand->siglock);
1017		write_unlock_irq(&tasklist_lock);
1018
1019		__cleanup_sighand(oldsighand);
1020	}
1021
1022	BUG_ON(!thread_group_leader(tsk));
1023	return 0;
 
1024
1025killed:
1026	/* protects against exit_notify() and __exit_signal() */
1027	read_lock(&tasklist_lock);
1028	sig->group_exit_task = NULL;
1029	sig->notify_count = 0;
1030	read_unlock(&tasklist_lock);
1031	return -EAGAIN;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1032}
1033
1034char *get_task_comm(char *buf, struct task_struct *tsk)
1035{
1036	/* buf must be at least sizeof(tsk->comm) in size */
1037	task_lock(tsk);
1038	strncpy(buf, tsk->comm, sizeof(tsk->comm));
1039	task_unlock(tsk);
1040	return buf;
1041}
1042EXPORT_SYMBOL_GPL(get_task_comm);
1043
1044/*
1045 * These functions flushes out all traces of the currently running executable
1046 * so that a new one can be started
1047 */
1048
1049void set_task_comm(struct task_struct *tsk, const char *buf)
1050{
1051	task_lock(tsk);
 
1052	trace_task_rename(tsk, buf);
 
 
 
 
 
 
 
 
 
1053	strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1054	task_unlock(tsk);
1055	perf_event_comm(tsk);
1056}
1057
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1058int flush_old_exec(struct linux_binprm * bprm)
1059{
1060	int retval;
1061
1062	/*
1063	 * Make sure we have a private signal table and that
1064	 * we are unassociated from the previous thread group.
1065	 */
1066	retval = de_thread(current);
1067	if (retval)
1068		goto out;
1069
1070	set_mm_exe_file(bprm->mm, bprm->file);
 
 
1071	/*
1072	 * Release all of the old mmap stuff
1073	 */
1074	acct_arg_size(bprm, 0);
1075	retval = exec_mmap(bprm->mm);
1076	if (retval)
1077		goto out;
1078
1079	bprm->mm = NULL;		/* We're using it now */
1080
1081	set_fs(USER_DS);
1082	current->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD |
1083					PF_NOFREEZE | PF_NO_SETAFFINITY);
1084	flush_thread();
1085	current->personality &= ~bprm->per_clear;
1086
1087	return 0;
1088
1089out:
1090	return retval;
1091}
1092EXPORT_SYMBOL(flush_old_exec);
1093
1094void would_dump(struct linux_binprm *bprm, struct file *file)
1095{
1096	if (inode_permission(file_inode(file), MAY_READ) < 0)
1097		bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1098}
1099EXPORT_SYMBOL(would_dump);
1100
1101void setup_new_exec(struct linux_binprm * bprm)
1102{
1103	arch_pick_mmap_layout(current->mm);
1104
1105	/* This is the point of no return */
1106	current->sas_ss_sp = current->sas_ss_size = 0;
1107
1108	if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid()))
1109		set_dumpable(current->mm, SUID_DUMP_USER);
1110	else
1111		set_dumpable(current->mm, suid_dumpable);
1112
1113	set_task_comm(current, kbasename(bprm->filename));
1114
1115	/* Set the new mm task size. We have to do that late because it may
1116	 * depend on TIF_32BIT which is only updated in flush_thread() on
1117	 * some architectures like powerpc
1118	 */
1119	current->mm->task_size = TASK_SIZE;
1120
1121	/* install the new credentials */
1122	if (!uid_eq(bprm->cred->uid, current_euid()) ||
1123	    !gid_eq(bprm->cred->gid, current_egid())) {
1124		current->pdeath_signal = 0;
1125	} else {
1126		would_dump(bprm, bprm->file);
1127		if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
1128			set_dumpable(current->mm, suid_dumpable);
1129	}
1130
 
 
 
 
 
 
 
1131	/* An exec changes our domain. We are no longer part of the thread
1132	   group */
 
1133	current->self_exec_id++;
 
1134	flush_signal_handlers(current, 0);
1135	do_close_on_exec(current->files);
1136}
1137EXPORT_SYMBOL(setup_new_exec);
1138
1139/*
1140 * Prepare credentials and lock ->cred_guard_mutex.
1141 * install_exec_creds() commits the new creds and drops the lock.
1142 * Or, if exec fails before, free_bprm() should release ->cred and
1143 * and unlock.
1144 */
1145int prepare_bprm_creds(struct linux_binprm *bprm)
1146{
1147	if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1148		return -ERESTARTNOINTR;
1149
1150	bprm->cred = prepare_exec_creds();
1151	if (likely(bprm->cred))
1152		return 0;
1153
1154	mutex_unlock(&current->signal->cred_guard_mutex);
1155	return -ENOMEM;
1156}
1157
1158static void free_bprm(struct linux_binprm *bprm)
1159{
1160	free_arg_pages(bprm);
1161	if (bprm->cred) {
1162		mutex_unlock(&current->signal->cred_guard_mutex);
1163		abort_creds(bprm->cred);
1164	}
1165	if (bprm->file) {
1166		allow_write_access(bprm->file);
1167		fput(bprm->file);
1168	}
1169	/* If a binfmt changed the interp, free it. */
1170	if (bprm->interp != bprm->filename)
1171		kfree(bprm->interp);
1172	kfree(bprm);
1173}
1174
1175int bprm_change_interp(char *interp, struct linux_binprm *bprm)
1176{
1177	/* If a binfmt changed the interp, free it first. */
1178	if (bprm->interp != bprm->filename)
1179		kfree(bprm->interp);
1180	bprm->interp = kstrdup(interp, GFP_KERNEL);
1181	if (!bprm->interp)
1182		return -ENOMEM;
1183	return 0;
1184}
1185EXPORT_SYMBOL(bprm_change_interp);
1186
1187/*
1188 * install the new credentials for this executable
1189 */
1190void install_exec_creds(struct linux_binprm *bprm)
1191{
1192	security_bprm_committing_creds(bprm);
1193
1194	commit_creds(bprm->cred);
1195	bprm->cred = NULL;
1196
1197	/*
1198	 * Disable monitoring for regular users
1199	 * when executing setuid binaries. Must
1200	 * wait until new credentials are committed
1201	 * by commit_creds() above
1202	 */
1203	if (get_dumpable(current->mm) != SUID_DUMP_USER)
1204		perf_event_exit_task(current);
1205	/*
1206	 * cred_guard_mutex must be held at least to this point to prevent
1207	 * ptrace_attach() from altering our determination of the task's
1208	 * credentials; any time after this it may be unlocked.
1209	 */
1210	security_bprm_committed_creds(bprm);
1211	mutex_unlock(&current->signal->cred_guard_mutex);
1212}
1213EXPORT_SYMBOL(install_exec_creds);
1214
1215/*
1216 * determine how safe it is to execute the proposed program
1217 * - the caller must hold ->cred_guard_mutex to protect against
1218 *   PTRACE_ATTACH
1219 */
1220static void check_unsafe_exec(struct linux_binprm *bprm)
1221{
1222	struct task_struct *p = current, *t;
1223	unsigned n_fs;
 
1224
1225	if (p->ptrace) {
1226		if (p->ptrace & PT_PTRACE_CAP)
1227			bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP;
1228		else
1229			bprm->unsafe |= LSM_UNSAFE_PTRACE;
1230	}
1231
1232	/*
1233	 * This isn't strictly necessary, but it makes it harder for LSMs to
1234	 * mess up.
1235	 */
1236	if (current->no_new_privs)
1237		bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1238
1239	t = p;
1240	n_fs = 1;
1241	spin_lock(&p->fs->lock);
1242	rcu_read_lock();
1243	while_each_thread(p, t) {
1244		if (t->fs == p->fs)
1245			n_fs++;
1246	}
1247	rcu_read_unlock();
1248
1249	if (p->fs->users > n_fs)
1250		bprm->unsafe |= LSM_UNSAFE_SHARE;
1251	else
1252		p->fs->in_exec = 1;
 
 
 
 
 
1253	spin_unlock(&p->fs->lock);
 
 
1254}
1255
1256/*
1257 * Fill the binprm structure from the inode.
1258 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1259 *
1260 * This may be called multiple times for binary chains (scripts for example).
1261 */
1262int prepare_binprm(struct linux_binprm *bprm)
1263{
1264	struct inode *inode = file_inode(bprm->file);
1265	umode_t mode = inode->i_mode;
1266	int retval;
1267
 
 
 
1268
1269	/* clear any previous set[ug]id data from a previous binary */
1270	bprm->cred->euid = current_euid();
1271	bprm->cred->egid = current_egid();
1272
1273	if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) &&
1274	    !current->no_new_privs &&
1275	    kuid_has_mapping(bprm->cred->user_ns, inode->i_uid) &&
1276	    kgid_has_mapping(bprm->cred->user_ns, inode->i_gid)) {
1277		/* Set-uid? */
1278		if (mode & S_ISUID) {
 
 
1279			bprm->per_clear |= PER_CLEAR_ON_SETID;
1280			bprm->cred->euid = inode->i_uid;
 
1281		}
1282
1283		/* Set-gid? */
1284		/*
1285		 * If setgid is set but no group execute bit then this
1286		 * is a candidate for mandatory locking, not a setgid
1287		 * executable.
1288		 */
1289		if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
 
 
1290			bprm->per_clear |= PER_CLEAR_ON_SETID;
1291			bprm->cred->egid = inode->i_gid;
1292		}
1293	}
1294
1295	/* fill in binprm security blob */
1296	retval = security_bprm_set_creds(bprm);
1297	if (retval)
1298		return retval;
1299	bprm->cred_prepared = 1;
1300
1301	memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1302	return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1303}
1304
1305EXPORT_SYMBOL(prepare_binprm);
1306
1307/*
1308 * Arguments are '\0' separated strings found at the location bprm->p
1309 * points to; chop off the first by relocating brpm->p to right after
1310 * the first '\0' encountered.
1311 */
1312int remove_arg_zero(struct linux_binprm *bprm)
1313{
1314	int ret = 0;
1315	unsigned long offset;
1316	char *kaddr;
1317	struct page *page;
1318
1319	if (!bprm->argc)
1320		return 0;
1321
1322	do {
1323		offset = bprm->p & ~PAGE_MASK;
1324		page = get_arg_page(bprm, bprm->p, 0);
1325		if (!page) {
1326			ret = -EFAULT;
1327			goto out;
1328		}
1329		kaddr = kmap_atomic(page);
1330
1331		for (; offset < PAGE_SIZE && kaddr[offset];
1332				offset++, bprm->p++)
1333			;
1334
1335		kunmap_atomic(kaddr);
1336		put_arg_page(page);
1337
1338		if (offset == PAGE_SIZE)
1339			free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1340	} while (offset == PAGE_SIZE);
1341
1342	bprm->p++;
1343	bprm->argc--;
1344	ret = 0;
1345
1346out:
1347	return ret;
1348}
1349EXPORT_SYMBOL(remove_arg_zero);
1350
1351#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1352/*
1353 * cycle the list of binary formats handler, until one recognizes the image
1354 */
1355int search_binary_handler(struct linux_binprm *bprm)
1356{
1357	bool need_retry = IS_ENABLED(CONFIG_MODULES);
 
1358	struct linux_binfmt *fmt;
1359	int retval;
1360
1361	/* This allows 4 levels of binfmt rewrites before failing hard. */
1362	if (bprm->recursion_depth > 5)
1363		return -ELOOP;
1364
1365	retval = security_bprm_check(bprm);
1366	if (retval)
1367		return retval;
1368
1369	retval = -ENOENT;
1370 retry:
1371	read_lock(&binfmt_lock);
1372	list_for_each_entry(fmt, &formats, lh) {
1373		if (!try_module_get(fmt->module))
1374			continue;
1375		read_unlock(&binfmt_lock);
1376		bprm->recursion_depth++;
1377		retval = fmt->load_binary(bprm);
1378		bprm->recursion_depth--;
1379		if (retval >= 0 || retval != -ENOEXEC ||
1380		    bprm->mm == NULL || bprm->file == NULL) {
1381			put_binfmt(fmt);
1382			return retval;
1383		}
1384		read_lock(&binfmt_lock);
1385		put_binfmt(fmt);
1386	}
1387	read_unlock(&binfmt_lock);
1388
1389	if (need_retry && retval == -ENOEXEC) {
1390		if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
1391		    printable(bprm->buf[2]) && printable(bprm->buf[3]))
1392			return retval;
1393		if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
1394			return retval;
1395		need_retry = false;
1396		goto retry;
1397	}
1398
1399	return retval;
1400}
1401EXPORT_SYMBOL(search_binary_handler);
1402
1403static int exec_binprm(struct linux_binprm *bprm)
1404{
1405	pid_t old_pid, old_vpid;
1406	int ret;
1407
1408	/* Need to fetch pid before load_binary changes it */
1409	old_pid = current->pid;
1410	rcu_read_lock();
1411	old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1412	rcu_read_unlock();
1413
1414	ret = search_binary_handler(bprm);
1415	if (ret >= 0) {
1416		audit_bprm(bprm);
1417		trace_sched_process_exec(current, old_pid, bprm);
1418		ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1419		proc_exec_connector(current);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1420	}
1421
1422	return ret;
1423}
1424
 
 
1425/*
1426 * sys_execve() executes a new program.
1427 */
1428static int do_execve_common(struct filename *filename,
1429				struct user_arg_ptr argv,
1430				struct user_arg_ptr envp)
 
1431{
1432	struct linux_binprm *bprm;
1433	struct file *file;
1434	struct files_struct *displaced;
 
1435	int retval;
1436
1437	if (IS_ERR(filename))
1438		return PTR_ERR(filename);
1439
1440	/*
1441	 * We move the actual failure in case of RLIMIT_NPROC excess from
1442	 * set*uid() to execve() because too many poorly written programs
1443	 * don't check setuid() return code.  Here we additionally recheck
1444	 * whether NPROC limit is still exceeded.
1445	 */
1446	if ((current->flags & PF_NPROC_EXCEEDED) &&
1447	    atomic_read(&current_user()->processes) > rlimit(RLIMIT_NPROC)) {
1448		retval = -EAGAIN;
1449		goto out_ret;
1450	}
1451
1452	/* We're below the limit (still or again), so we don't want to make
1453	 * further execve() calls fail. */
1454	current->flags &= ~PF_NPROC_EXCEEDED;
1455
1456	retval = unshare_files(&displaced);
1457	if (retval)
1458		goto out_ret;
1459
1460	retval = -ENOMEM;
1461	bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1462	if (!bprm)
1463		goto out_files;
1464
1465	retval = prepare_bprm_creds(bprm);
1466	if (retval)
1467		goto out_free;
1468
1469	check_unsafe_exec(bprm);
 
 
 
1470	current->in_execve = 1;
1471
1472	file = do_open_exec(filename);
1473	retval = PTR_ERR(file);
1474	if (IS_ERR(file))
1475		goto out_unmark;
1476
1477	sched_exec();
1478
1479	bprm->file = file;
1480	bprm->filename = bprm->interp = filename->name;
 
1481
1482	retval = bprm_mm_init(bprm);
1483	if (retval)
1484		goto out_unmark;
1485
1486	bprm->argc = count(argv, MAX_ARG_STRINGS);
1487	if ((retval = bprm->argc) < 0)
1488		goto out;
1489
1490	bprm->envc = count(envp, MAX_ARG_STRINGS);
1491	if ((retval = bprm->envc) < 0)
1492		goto out;
1493
1494	retval = prepare_binprm(bprm);
1495	if (retval < 0)
1496		goto out;
1497
1498	retval = copy_strings_kernel(1, &bprm->filename, bprm);
1499	if (retval < 0)
1500		goto out;
1501
1502	bprm->exec = bprm->p;
1503	retval = copy_strings(bprm->envc, envp, bprm);
1504	if (retval < 0)
1505		goto out;
1506
1507	retval = copy_strings(bprm->argc, argv, bprm);
1508	if (retval < 0)
1509		goto out;
1510
1511	retval = exec_binprm(bprm);
1512	if (retval < 0)
1513		goto out;
1514
1515	/* execve succeeded */
1516	current->fs->in_exec = 0;
1517	current->in_execve = 0;
1518	acct_update_integrals(current);
1519	task_numa_free(current);
1520	free_bprm(bprm);
1521	putname(filename);
1522	if (displaced)
1523		put_files_struct(displaced);
1524	return retval;
1525
1526out:
1527	if (bprm->mm) {
1528		acct_arg_size(bprm, 0);
1529		mmput(bprm->mm);
1530	}
1531
 
 
 
 
 
 
1532out_unmark:
1533	current->fs->in_exec = 0;
 
1534	current->in_execve = 0;
1535
1536out_free:
1537	free_bprm(bprm);
1538
1539out_files:
1540	if (displaced)
1541		reset_files_struct(displaced);
1542out_ret:
1543	putname(filename);
1544	return retval;
1545}
1546
1547int do_execve(struct filename *filename,
1548	const char __user *const __user *__argv,
1549	const char __user *const __user *__envp)
 
1550{
1551	struct user_arg_ptr argv = { .ptr.native = __argv };
1552	struct user_arg_ptr envp = { .ptr.native = __envp };
1553	return do_execve_common(filename, argv, envp);
1554}
1555
1556#ifdef CONFIG_COMPAT
1557static int compat_do_execve(struct filename *filename,
1558	const compat_uptr_t __user *__argv,
1559	const compat_uptr_t __user *__envp)
 
1560{
1561	struct user_arg_ptr argv = {
1562		.is_compat = true,
1563		.ptr.compat = __argv,
1564	};
1565	struct user_arg_ptr envp = {
1566		.is_compat = true,
1567		.ptr.compat = __envp,
1568	};
1569	return do_execve_common(filename, argv, envp);
1570}
1571#endif
1572
1573void set_binfmt(struct linux_binfmt *new)
1574{
1575	struct mm_struct *mm = current->mm;
1576
1577	if (mm->binfmt)
1578		module_put(mm->binfmt->module);
1579
1580	mm->binfmt = new;
1581	if (new)
1582		__module_get(new->module);
1583}
 
1584EXPORT_SYMBOL(set_binfmt);
1585
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1586/*
1587 * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1588 */
1589void set_dumpable(struct mm_struct *mm, int value)
1590{
1591	unsigned long old, new;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1592
1593	if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
1594		return;
 
1595
1596	do {
1597		old = ACCESS_ONCE(mm->flags);
1598		new = (old & ~MMF_DUMPABLE_MASK) | value;
1599	} while (cmpxchg(&mm->flags, old, new) != old);
1600}
1601
1602SYSCALL_DEFINE3(execve,
1603		const char __user *, filename,
1604		const char __user *const __user *, argv,
1605		const char __user *const __user *, envp)
1606{
1607	return do_execve(getname(filename), argv, envp);
1608}
1609#ifdef CONFIG_COMPAT
1610COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
1611	const compat_uptr_t __user *, argv,
1612	const compat_uptr_t __user *, envp)
1613{
1614	return compat_do_execve(getname(filename), argv, envp);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1615}
1616#endif