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1// SPDX-License-Identifier: GPL-2.0-only
2#include <linux/mm.h>
3#include <linux/slab.h>
4#include <linux/string.h>
5#include <linux/compiler.h>
6#include <linux/export.h>
7#include <linux/err.h>
8#include <linux/sched.h>
9#include <linux/sched/mm.h>
10#include <linux/sched/signal.h>
11#include <linux/sched/task_stack.h>
12#include <linux/security.h>
13#include <linux/swap.h>
14#include <linux/swapops.h>
15#include <linux/mman.h>
16#include <linux/hugetlb.h>
17#include <linux/vmalloc.h>
18#include <linux/userfaultfd_k.h>
19#include <linux/elf.h>
20#include <linux/elf-randomize.h>
21#include <linux/personality.h>
22#include <linux/random.h>
23#include <linux/processor.h>
24#include <linux/sizes.h>
25#include <linux/compat.h>
26
27#include <linux/uaccess.h>
28
29#include "internal.h"
30
31/**
32 * kfree_const - conditionally free memory
33 * @x: pointer to the memory
34 *
35 * Function calls kfree only if @x is not in .rodata section.
36 */
37void kfree_const(const void *x)
38{
39 if (!is_kernel_rodata((unsigned long)x))
40 kfree(x);
41}
42EXPORT_SYMBOL(kfree_const);
43
44/**
45 * kstrdup - allocate space for and copy an existing string
46 * @s: the string to duplicate
47 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
48 *
49 * Return: newly allocated copy of @s or %NULL in case of error
50 */
51char *kstrdup(const char *s, gfp_t gfp)
52{
53 size_t len;
54 char *buf;
55
56 if (!s)
57 return NULL;
58
59 len = strlen(s) + 1;
60 buf = kmalloc_track_caller(len, gfp);
61 if (buf)
62 memcpy(buf, s, len);
63 return buf;
64}
65EXPORT_SYMBOL(kstrdup);
66
67/**
68 * kstrdup_const - conditionally duplicate an existing const string
69 * @s: the string to duplicate
70 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
71 *
72 * Note: Strings allocated by kstrdup_const should be freed by kfree_const.
73 *
74 * Return: source string if it is in .rodata section otherwise
75 * fallback to kstrdup.
76 */
77const char *kstrdup_const(const char *s, gfp_t gfp)
78{
79 if (is_kernel_rodata((unsigned long)s))
80 return s;
81
82 return kstrdup(s, gfp);
83}
84EXPORT_SYMBOL(kstrdup_const);
85
86/**
87 * kstrndup - allocate space for and copy an existing string
88 * @s: the string to duplicate
89 * @max: read at most @max chars from @s
90 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
91 *
92 * Note: Use kmemdup_nul() instead if the size is known exactly.
93 *
94 * Return: newly allocated copy of @s or %NULL in case of error
95 */
96char *kstrndup(const char *s, size_t max, gfp_t gfp)
97{
98 size_t len;
99 char *buf;
100
101 if (!s)
102 return NULL;
103
104 len = strnlen(s, max);
105 buf = kmalloc_track_caller(len+1, gfp);
106 if (buf) {
107 memcpy(buf, s, len);
108 buf[len] = '\0';
109 }
110 return buf;
111}
112EXPORT_SYMBOL(kstrndup);
113
114/**
115 * kmemdup - duplicate region of memory
116 *
117 * @src: memory region to duplicate
118 * @len: memory region length
119 * @gfp: GFP mask to use
120 *
121 * Return: newly allocated copy of @src or %NULL in case of error
122 */
123void *kmemdup(const void *src, size_t len, gfp_t gfp)
124{
125 void *p;
126
127 p = kmalloc_track_caller(len, gfp);
128 if (p)
129 memcpy(p, src, len);
130 return p;
131}
132EXPORT_SYMBOL(kmemdup);
133
134/**
135 * kmemdup_nul - Create a NUL-terminated string from unterminated data
136 * @s: The data to stringify
137 * @len: The size of the data
138 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
139 *
140 * Return: newly allocated copy of @s with NUL-termination or %NULL in
141 * case of error
142 */
143char *kmemdup_nul(const char *s, size_t len, gfp_t gfp)
144{
145 char *buf;
146
147 if (!s)
148 return NULL;
149
150 buf = kmalloc_track_caller(len + 1, gfp);
151 if (buf) {
152 memcpy(buf, s, len);
153 buf[len] = '\0';
154 }
155 return buf;
156}
157EXPORT_SYMBOL(kmemdup_nul);
158
159/**
160 * memdup_user - duplicate memory region from user space
161 *
162 * @src: source address in user space
163 * @len: number of bytes to copy
164 *
165 * Return: an ERR_PTR() on failure. Result is physically
166 * contiguous, to be freed by kfree().
167 */
168void *memdup_user(const void __user *src, size_t len)
169{
170 void *p;
171
172 p = kmalloc_track_caller(len, GFP_USER | __GFP_NOWARN);
173 if (!p)
174 return ERR_PTR(-ENOMEM);
175
176 if (copy_from_user(p, src, len)) {
177 kfree(p);
178 return ERR_PTR(-EFAULT);
179 }
180
181 return p;
182}
183EXPORT_SYMBOL(memdup_user);
184
185/**
186 * vmemdup_user - duplicate memory region from user space
187 *
188 * @src: source address in user space
189 * @len: number of bytes to copy
190 *
191 * Return: an ERR_PTR() on failure. Result may be not
192 * physically contiguous. Use kvfree() to free.
193 */
194void *vmemdup_user(const void __user *src, size_t len)
195{
196 void *p;
197
198 p = kvmalloc(len, GFP_USER);
199 if (!p)
200 return ERR_PTR(-ENOMEM);
201
202 if (copy_from_user(p, src, len)) {
203 kvfree(p);
204 return ERR_PTR(-EFAULT);
205 }
206
207 return p;
208}
209EXPORT_SYMBOL(vmemdup_user);
210
211/**
212 * strndup_user - duplicate an existing string from user space
213 * @s: The string to duplicate
214 * @n: Maximum number of bytes to copy, including the trailing NUL.
215 *
216 * Return: newly allocated copy of @s or an ERR_PTR() in case of error
217 */
218char *strndup_user(const char __user *s, long n)
219{
220 char *p;
221 long length;
222
223 length = strnlen_user(s, n);
224
225 if (!length)
226 return ERR_PTR(-EFAULT);
227
228 if (length > n)
229 return ERR_PTR(-EINVAL);
230
231 p = memdup_user(s, length);
232
233 if (IS_ERR(p))
234 return p;
235
236 p[length - 1] = '\0';
237
238 return p;
239}
240EXPORT_SYMBOL(strndup_user);
241
242/**
243 * memdup_user_nul - duplicate memory region from user space and NUL-terminate
244 *
245 * @src: source address in user space
246 * @len: number of bytes to copy
247 *
248 * Return: an ERR_PTR() on failure.
249 */
250void *memdup_user_nul(const void __user *src, size_t len)
251{
252 char *p;
253
254 /*
255 * Always use GFP_KERNEL, since copy_from_user() can sleep and
256 * cause pagefault, which makes it pointless to use GFP_NOFS
257 * or GFP_ATOMIC.
258 */
259 p = kmalloc_track_caller(len + 1, GFP_KERNEL);
260 if (!p)
261 return ERR_PTR(-ENOMEM);
262
263 if (copy_from_user(p, src, len)) {
264 kfree(p);
265 return ERR_PTR(-EFAULT);
266 }
267 p[len] = '\0';
268
269 return p;
270}
271EXPORT_SYMBOL(memdup_user_nul);
272
273void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
274 struct vm_area_struct *prev, struct rb_node *rb_parent)
275{
276 struct vm_area_struct *next;
277
278 vma->vm_prev = prev;
279 if (prev) {
280 next = prev->vm_next;
281 prev->vm_next = vma;
282 } else {
283 mm->mmap = vma;
284 if (rb_parent)
285 next = rb_entry(rb_parent,
286 struct vm_area_struct, vm_rb);
287 else
288 next = NULL;
289 }
290 vma->vm_next = next;
291 if (next)
292 next->vm_prev = vma;
293}
294
295/* Check if the vma is being used as a stack by this task */
296int vma_is_stack_for_current(struct vm_area_struct *vma)
297{
298 struct task_struct * __maybe_unused t = current;
299
300 return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
301}
302
303#ifndef STACK_RND_MASK
304#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) /* 8MB of VA */
305#endif
306
307unsigned long randomize_stack_top(unsigned long stack_top)
308{
309 unsigned long random_variable = 0;
310
311 if (current->flags & PF_RANDOMIZE) {
312 random_variable = get_random_long();
313 random_variable &= STACK_RND_MASK;
314 random_variable <<= PAGE_SHIFT;
315 }
316#ifdef CONFIG_STACK_GROWSUP
317 return PAGE_ALIGN(stack_top) + random_variable;
318#else
319 return PAGE_ALIGN(stack_top) - random_variable;
320#endif
321}
322
323#ifdef CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
324unsigned long arch_randomize_brk(struct mm_struct *mm)
325{
326 /* Is the current task 32bit ? */
327 if (!IS_ENABLED(CONFIG_64BIT) || is_compat_task())
328 return randomize_page(mm->brk, SZ_32M);
329
330 return randomize_page(mm->brk, SZ_1G);
331}
332
333unsigned long arch_mmap_rnd(void)
334{
335 unsigned long rnd;
336
337#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
338 if (is_compat_task())
339 rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
340 else
341#endif /* CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS */
342 rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
343
344 return rnd << PAGE_SHIFT;
345}
346
347static int mmap_is_legacy(struct rlimit *rlim_stack)
348{
349 if (current->personality & ADDR_COMPAT_LAYOUT)
350 return 1;
351
352 if (rlim_stack->rlim_cur == RLIM_INFINITY)
353 return 1;
354
355 return sysctl_legacy_va_layout;
356}
357
358/*
359 * Leave enough space between the mmap area and the stack to honour ulimit in
360 * the face of randomisation.
361 */
362#define MIN_GAP (SZ_128M)
363#define MAX_GAP (STACK_TOP / 6 * 5)
364
365static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
366{
367 unsigned long gap = rlim_stack->rlim_cur;
368 unsigned long pad = stack_guard_gap;
369
370 /* Account for stack randomization if necessary */
371 if (current->flags & PF_RANDOMIZE)
372 pad += (STACK_RND_MASK << PAGE_SHIFT);
373
374 /* Values close to RLIM_INFINITY can overflow. */
375 if (gap + pad > gap)
376 gap += pad;
377
378 if (gap < MIN_GAP)
379 gap = MIN_GAP;
380 else if (gap > MAX_GAP)
381 gap = MAX_GAP;
382
383 return PAGE_ALIGN(STACK_TOP - gap - rnd);
384}
385
386void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
387{
388 unsigned long random_factor = 0UL;
389
390 if (current->flags & PF_RANDOMIZE)
391 random_factor = arch_mmap_rnd();
392
393 if (mmap_is_legacy(rlim_stack)) {
394 mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
395 mm->get_unmapped_area = arch_get_unmapped_area;
396 } else {
397 mm->mmap_base = mmap_base(random_factor, rlim_stack);
398 mm->get_unmapped_area = arch_get_unmapped_area_topdown;
399 }
400}
401#elif defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
402void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
403{
404 mm->mmap_base = TASK_UNMAPPED_BASE;
405 mm->get_unmapped_area = arch_get_unmapped_area;
406}
407#endif
408
409/**
410 * __account_locked_vm - account locked pages to an mm's locked_vm
411 * @mm: mm to account against
412 * @pages: number of pages to account
413 * @inc: %true if @pages should be considered positive, %false if not
414 * @task: task used to check RLIMIT_MEMLOCK
415 * @bypass_rlim: %true if checking RLIMIT_MEMLOCK should be skipped
416 *
417 * Assumes @task and @mm are valid (i.e. at least one reference on each), and
418 * that mmap_sem is held as writer.
419 *
420 * Return:
421 * * 0 on success
422 * * -ENOMEM if RLIMIT_MEMLOCK would be exceeded.
423 */
424int __account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc,
425 struct task_struct *task, bool bypass_rlim)
426{
427 unsigned long locked_vm, limit;
428 int ret = 0;
429
430 lockdep_assert_held_write(&mm->mmap_sem);
431
432 locked_vm = mm->locked_vm;
433 if (inc) {
434 if (!bypass_rlim) {
435 limit = task_rlimit(task, RLIMIT_MEMLOCK) >> PAGE_SHIFT;
436 if (locked_vm + pages > limit)
437 ret = -ENOMEM;
438 }
439 if (!ret)
440 mm->locked_vm = locked_vm + pages;
441 } else {
442 WARN_ON_ONCE(pages > locked_vm);
443 mm->locked_vm = locked_vm - pages;
444 }
445
446 pr_debug("%s: [%d] caller %ps %c%lu %lu/%lu%s\n", __func__, task->pid,
447 (void *)_RET_IP_, (inc) ? '+' : '-', pages << PAGE_SHIFT,
448 locked_vm << PAGE_SHIFT, task_rlimit(task, RLIMIT_MEMLOCK),
449 ret ? " - exceeded" : "");
450
451 return ret;
452}
453EXPORT_SYMBOL_GPL(__account_locked_vm);
454
455/**
456 * account_locked_vm - account locked pages to an mm's locked_vm
457 * @mm: mm to account against, may be NULL
458 * @pages: number of pages to account
459 * @inc: %true if @pages should be considered positive, %false if not
460 *
461 * Assumes a non-NULL @mm is valid (i.e. at least one reference on it).
462 *
463 * Return:
464 * * 0 on success, or if mm is NULL
465 * * -ENOMEM if RLIMIT_MEMLOCK would be exceeded.
466 */
467int account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc)
468{
469 int ret;
470
471 if (pages == 0 || !mm)
472 return 0;
473
474 down_write(&mm->mmap_sem);
475 ret = __account_locked_vm(mm, pages, inc, current,
476 capable(CAP_IPC_LOCK));
477 up_write(&mm->mmap_sem);
478
479 return ret;
480}
481EXPORT_SYMBOL_GPL(account_locked_vm);
482
483unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
484 unsigned long len, unsigned long prot,
485 unsigned long flag, unsigned long pgoff)
486{
487 unsigned long ret;
488 struct mm_struct *mm = current->mm;
489 unsigned long populate;
490 LIST_HEAD(uf);
491
492 ret = security_mmap_file(file, prot, flag);
493 if (!ret) {
494 if (down_write_killable(&mm->mmap_sem))
495 return -EINTR;
496 ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
497 &populate, &uf);
498 up_write(&mm->mmap_sem);
499 userfaultfd_unmap_complete(mm, &uf);
500 if (populate)
501 mm_populate(ret, populate);
502 }
503 return ret;
504}
505
506unsigned long vm_mmap(struct file *file, unsigned long addr,
507 unsigned long len, unsigned long prot,
508 unsigned long flag, unsigned long offset)
509{
510 if (unlikely(offset + PAGE_ALIGN(len) < offset))
511 return -EINVAL;
512 if (unlikely(offset_in_page(offset)))
513 return -EINVAL;
514
515 return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
516}
517EXPORT_SYMBOL(vm_mmap);
518
519/**
520 * kvmalloc_node - attempt to allocate physically contiguous memory, but upon
521 * failure, fall back to non-contiguous (vmalloc) allocation.
522 * @size: size of the request.
523 * @flags: gfp mask for the allocation - must be compatible (superset) with GFP_KERNEL.
524 * @node: numa node to allocate from
525 *
526 * Uses kmalloc to get the memory but if the allocation fails then falls back
527 * to the vmalloc allocator. Use kvfree for freeing the memory.
528 *
529 * Reclaim modifiers - __GFP_NORETRY and __GFP_NOFAIL are not supported.
530 * __GFP_RETRY_MAYFAIL is supported, and it should be used only if kmalloc is
531 * preferable to the vmalloc fallback, due to visible performance drawbacks.
532 *
533 * Please note that any use of gfp flags outside of GFP_KERNEL is careful to not
534 * fall back to vmalloc.
535 *
536 * Return: pointer to the allocated memory of %NULL in case of failure
537 */
538void *kvmalloc_node(size_t size, gfp_t flags, int node)
539{
540 gfp_t kmalloc_flags = flags;
541 void *ret;
542
543 /*
544 * vmalloc uses GFP_KERNEL for some internal allocations (e.g page tables)
545 * so the given set of flags has to be compatible.
546 */
547 if ((flags & GFP_KERNEL) != GFP_KERNEL)
548 return kmalloc_node(size, flags, node);
549
550 /*
551 * We want to attempt a large physically contiguous block first because
552 * it is less likely to fragment multiple larger blocks and therefore
553 * contribute to a long term fragmentation less than vmalloc fallback.
554 * However make sure that larger requests are not too disruptive - no
555 * OOM killer and no allocation failure warnings as we have a fallback.
556 */
557 if (size > PAGE_SIZE) {
558 kmalloc_flags |= __GFP_NOWARN;
559
560 if (!(kmalloc_flags & __GFP_RETRY_MAYFAIL))
561 kmalloc_flags |= __GFP_NORETRY;
562 }
563
564 ret = kmalloc_node(size, kmalloc_flags, node);
565
566 /*
567 * It doesn't really make sense to fallback to vmalloc for sub page
568 * requests
569 */
570 if (ret || size <= PAGE_SIZE)
571 return ret;
572
573 return __vmalloc_node_flags_caller(size, node, flags,
574 __builtin_return_address(0));
575}
576EXPORT_SYMBOL(kvmalloc_node);
577
578/**
579 * kvfree() - Free memory.
580 * @addr: Pointer to allocated memory.
581 *
582 * kvfree frees memory allocated by any of vmalloc(), kmalloc() or kvmalloc().
583 * It is slightly more efficient to use kfree() or vfree() if you are certain
584 * that you know which one to use.
585 *
586 * Context: Either preemptible task context or not-NMI interrupt.
587 */
588void kvfree(const void *addr)
589{
590 if (is_vmalloc_addr(addr))
591 vfree(addr);
592 else
593 kfree(addr);
594}
595EXPORT_SYMBOL(kvfree);
596
597static inline void *__page_rmapping(struct page *page)
598{
599 unsigned long mapping;
600
601 mapping = (unsigned long)page->mapping;
602 mapping &= ~PAGE_MAPPING_FLAGS;
603
604 return (void *)mapping;
605}
606
607/* Neutral page->mapping pointer to address_space or anon_vma or other */
608void *page_rmapping(struct page *page)
609{
610 page = compound_head(page);
611 return __page_rmapping(page);
612}
613
614/*
615 * Return true if this page is mapped into pagetables.
616 * For compound page it returns true if any subpage of compound page is mapped.
617 */
618bool page_mapped(struct page *page)
619{
620 int i;
621
622 if (likely(!PageCompound(page)))
623 return atomic_read(&page->_mapcount) >= 0;
624 page = compound_head(page);
625 if (atomic_read(compound_mapcount_ptr(page)) >= 0)
626 return true;
627 if (PageHuge(page))
628 return false;
629 for (i = 0; i < compound_nr(page); i++) {
630 if (atomic_read(&page[i]._mapcount) >= 0)
631 return true;
632 }
633 return false;
634}
635EXPORT_SYMBOL(page_mapped);
636
637struct anon_vma *page_anon_vma(struct page *page)
638{
639 unsigned long mapping;
640
641 page = compound_head(page);
642 mapping = (unsigned long)page->mapping;
643 if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
644 return NULL;
645 return __page_rmapping(page);
646}
647
648struct address_space *page_mapping(struct page *page)
649{
650 struct address_space *mapping;
651
652 page = compound_head(page);
653
654 /* This happens if someone calls flush_dcache_page on slab page */
655 if (unlikely(PageSlab(page)))
656 return NULL;
657
658 if (unlikely(PageSwapCache(page))) {
659 swp_entry_t entry;
660
661 entry.val = page_private(page);
662 return swap_address_space(entry);
663 }
664
665 mapping = page->mapping;
666 if ((unsigned long)mapping & PAGE_MAPPING_ANON)
667 return NULL;
668
669 return (void *)((unsigned long)mapping & ~PAGE_MAPPING_FLAGS);
670}
671EXPORT_SYMBOL(page_mapping);
672
673/*
674 * For file cache pages, return the address_space, otherwise return NULL
675 */
676struct address_space *page_mapping_file(struct page *page)
677{
678 if (unlikely(PageSwapCache(page)))
679 return NULL;
680 return page_mapping(page);
681}
682
683/* Slow path of page_mapcount() for compound pages */
684int __page_mapcount(struct page *page)
685{
686 int ret;
687
688 ret = atomic_read(&page->_mapcount) + 1;
689 /*
690 * For file THP page->_mapcount contains total number of mapping
691 * of the page: no need to look into compound_mapcount.
692 */
693 if (!PageAnon(page) && !PageHuge(page))
694 return ret;
695 page = compound_head(page);
696 ret += atomic_read(compound_mapcount_ptr(page)) + 1;
697 if (PageDoubleMap(page))
698 ret--;
699 return ret;
700}
701EXPORT_SYMBOL_GPL(__page_mapcount);
702
703int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;
704int sysctl_overcommit_ratio __read_mostly = 50;
705unsigned long sysctl_overcommit_kbytes __read_mostly;
706int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
707unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
708unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
709
710int overcommit_ratio_handler(struct ctl_table *table, int write,
711 void __user *buffer, size_t *lenp,
712 loff_t *ppos)
713{
714 int ret;
715
716 ret = proc_dointvec(table, write, buffer, lenp, ppos);
717 if (ret == 0 && write)
718 sysctl_overcommit_kbytes = 0;
719 return ret;
720}
721
722int overcommit_kbytes_handler(struct ctl_table *table, int write,
723 void __user *buffer, size_t *lenp,
724 loff_t *ppos)
725{
726 int ret;
727
728 ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
729 if (ret == 0 && write)
730 sysctl_overcommit_ratio = 0;
731 return ret;
732}
733
734/*
735 * Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
736 */
737unsigned long vm_commit_limit(void)
738{
739 unsigned long allowed;
740
741 if (sysctl_overcommit_kbytes)
742 allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10);
743 else
744 allowed = ((totalram_pages() - hugetlb_total_pages())
745 * sysctl_overcommit_ratio / 100);
746 allowed += total_swap_pages;
747
748 return allowed;
749}
750
751/*
752 * Make sure vm_committed_as in one cacheline and not cacheline shared with
753 * other variables. It can be updated by several CPUs frequently.
754 */
755struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
756
757/*
758 * The global memory commitment made in the system can be a metric
759 * that can be used to drive ballooning decisions when Linux is hosted
760 * as a guest. On Hyper-V, the host implements a policy engine for dynamically
761 * balancing memory across competing virtual machines that are hosted.
762 * Several metrics drive this policy engine including the guest reported
763 * memory commitment.
764 */
765unsigned long vm_memory_committed(void)
766{
767 return percpu_counter_read_positive(&vm_committed_as);
768}
769EXPORT_SYMBOL_GPL(vm_memory_committed);
770
771/*
772 * Check that a process has enough memory to allocate a new virtual
773 * mapping. 0 means there is enough memory for the allocation to
774 * succeed and -ENOMEM implies there is not.
775 *
776 * We currently support three overcommit policies, which are set via the
777 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting.rst
778 *
779 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
780 * Additional code 2002 Jul 20 by Robert Love.
781 *
782 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
783 *
784 * Note this is a helper function intended to be used by LSMs which
785 * wish to use this logic.
786 */
787int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
788{
789 long allowed;
790
791 VM_WARN_ONCE(percpu_counter_read(&vm_committed_as) <
792 -(s64)vm_committed_as_batch * num_online_cpus(),
793 "memory commitment underflow");
794
795 vm_acct_memory(pages);
796
797 /*
798 * Sometimes we want to use more memory than we have
799 */
800 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
801 return 0;
802
803 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
804 if (pages > totalram_pages() + total_swap_pages)
805 goto error;
806 return 0;
807 }
808
809 allowed = vm_commit_limit();
810 /*
811 * Reserve some for root
812 */
813 if (!cap_sys_admin)
814 allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
815
816 /*
817 * Don't let a single process grow so big a user can't recover
818 */
819 if (mm) {
820 long reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
821
822 allowed -= min_t(long, mm->total_vm / 32, reserve);
823 }
824
825 if (percpu_counter_read_positive(&vm_committed_as) < allowed)
826 return 0;
827error:
828 vm_unacct_memory(pages);
829
830 return -ENOMEM;
831}
832
833/**
834 * get_cmdline() - copy the cmdline value to a buffer.
835 * @task: the task whose cmdline value to copy.
836 * @buffer: the buffer to copy to.
837 * @buflen: the length of the buffer. Larger cmdline values are truncated
838 * to this length.
839 *
840 * Return: the size of the cmdline field copied. Note that the copy does
841 * not guarantee an ending NULL byte.
842 */
843int get_cmdline(struct task_struct *task, char *buffer, int buflen)
844{
845 int res = 0;
846 unsigned int len;
847 struct mm_struct *mm = get_task_mm(task);
848 unsigned long arg_start, arg_end, env_start, env_end;
849 if (!mm)
850 goto out;
851 if (!mm->arg_end)
852 goto out_mm; /* Shh! No looking before we're done */
853
854 spin_lock(&mm->arg_lock);
855 arg_start = mm->arg_start;
856 arg_end = mm->arg_end;
857 env_start = mm->env_start;
858 env_end = mm->env_end;
859 spin_unlock(&mm->arg_lock);
860
861 len = arg_end - arg_start;
862
863 if (len > buflen)
864 len = buflen;
865
866 res = access_process_vm(task, arg_start, buffer, len, FOLL_FORCE);
867
868 /*
869 * If the nul at the end of args has been overwritten, then
870 * assume application is using setproctitle(3).
871 */
872 if (res > 0 && buffer[res-1] != '\0' && len < buflen) {
873 len = strnlen(buffer, res);
874 if (len < res) {
875 res = len;
876 } else {
877 len = env_end - env_start;
878 if (len > buflen - res)
879 len = buflen - res;
880 res += access_process_vm(task, env_start,
881 buffer+res, len,
882 FOLL_FORCE);
883 res = strnlen(buffer, res);
884 }
885 }
886out_mm:
887 mmput(mm);
888out:
889 return res;
890}
891
892int memcmp_pages(struct page *page1, struct page *page2)
893{
894 char *addr1, *addr2;
895 int ret;
896
897 addr1 = kmap_atomic(page1);
898 addr2 = kmap_atomic(page2);
899 ret = memcmp(addr1, addr2, PAGE_SIZE);
900 kunmap_atomic(addr2);
901 kunmap_atomic(addr1);
902 return ret;
903}
1#include <linux/mm.h>
2#include <linux/slab.h>
3#include <linux/string.h>
4#include <linux/compiler.h>
5#include <linux/export.h>
6#include <linux/err.h>
7#include <linux/sched.h>
8#include <linux/security.h>
9#include <linux/swap.h>
10#include <linux/swapops.h>
11#include <linux/mman.h>
12#include <linux/hugetlb.h>
13#include <linux/vmalloc.h>
14
15#include <asm/uaccess.h>
16
17#include "internal.h"
18
19#define CREATE_TRACE_POINTS
20#include <trace/events/kmem.h>
21
22/**
23 * kstrdup - allocate space for and copy an existing string
24 * @s: the string to duplicate
25 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
26 */
27char *kstrdup(const char *s, gfp_t gfp)
28{
29 size_t len;
30 char *buf;
31
32 if (!s)
33 return NULL;
34
35 len = strlen(s) + 1;
36 buf = kmalloc_track_caller(len, gfp);
37 if (buf)
38 memcpy(buf, s, len);
39 return buf;
40}
41EXPORT_SYMBOL(kstrdup);
42
43/**
44 * kstrndup - allocate space for and copy an existing string
45 * @s: the string to duplicate
46 * @max: read at most @max chars from @s
47 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
48 */
49char *kstrndup(const char *s, size_t max, gfp_t gfp)
50{
51 size_t len;
52 char *buf;
53
54 if (!s)
55 return NULL;
56
57 len = strnlen(s, max);
58 buf = kmalloc_track_caller(len+1, gfp);
59 if (buf) {
60 memcpy(buf, s, len);
61 buf[len] = '\0';
62 }
63 return buf;
64}
65EXPORT_SYMBOL(kstrndup);
66
67/**
68 * kmemdup - duplicate region of memory
69 *
70 * @src: memory region to duplicate
71 * @len: memory region length
72 * @gfp: GFP mask to use
73 */
74void *kmemdup(const void *src, size_t len, gfp_t gfp)
75{
76 void *p;
77
78 p = kmalloc_track_caller(len, gfp);
79 if (p)
80 memcpy(p, src, len);
81 return p;
82}
83EXPORT_SYMBOL(kmemdup);
84
85/**
86 * memdup_user - duplicate memory region from user space
87 *
88 * @src: source address in user space
89 * @len: number of bytes to copy
90 *
91 * Returns an ERR_PTR() on failure.
92 */
93void *memdup_user(const void __user *src, size_t len)
94{
95 void *p;
96
97 /*
98 * Always use GFP_KERNEL, since copy_from_user() can sleep and
99 * cause pagefault, which makes it pointless to use GFP_NOFS
100 * or GFP_ATOMIC.
101 */
102 p = kmalloc_track_caller(len, GFP_KERNEL);
103 if (!p)
104 return ERR_PTR(-ENOMEM);
105
106 if (copy_from_user(p, src, len)) {
107 kfree(p);
108 return ERR_PTR(-EFAULT);
109 }
110
111 return p;
112}
113EXPORT_SYMBOL(memdup_user);
114
115static __always_inline void *__do_krealloc(const void *p, size_t new_size,
116 gfp_t flags)
117{
118 void *ret;
119 size_t ks = 0;
120
121 if (p)
122 ks = ksize(p);
123
124 if (ks >= new_size)
125 return (void *)p;
126
127 ret = kmalloc_track_caller(new_size, flags);
128 if (ret && p)
129 memcpy(ret, p, ks);
130
131 return ret;
132}
133
134/**
135 * __krealloc - like krealloc() but don't free @p.
136 * @p: object to reallocate memory for.
137 * @new_size: how many bytes of memory are required.
138 * @flags: the type of memory to allocate.
139 *
140 * This function is like krealloc() except it never frees the originally
141 * allocated buffer. Use this if you don't want to free the buffer immediately
142 * like, for example, with RCU.
143 */
144void *__krealloc(const void *p, size_t new_size, gfp_t flags)
145{
146 if (unlikely(!new_size))
147 return ZERO_SIZE_PTR;
148
149 return __do_krealloc(p, new_size, flags);
150
151}
152EXPORT_SYMBOL(__krealloc);
153
154/**
155 * krealloc - reallocate memory. The contents will remain unchanged.
156 * @p: object to reallocate memory for.
157 * @new_size: how many bytes of memory are required.
158 * @flags: the type of memory to allocate.
159 *
160 * The contents of the object pointed to are preserved up to the
161 * lesser of the new and old sizes. If @p is %NULL, krealloc()
162 * behaves exactly like kmalloc(). If @new_size is 0 and @p is not a
163 * %NULL pointer, the object pointed to is freed.
164 */
165void *krealloc(const void *p, size_t new_size, gfp_t flags)
166{
167 void *ret;
168
169 if (unlikely(!new_size)) {
170 kfree(p);
171 return ZERO_SIZE_PTR;
172 }
173
174 ret = __do_krealloc(p, new_size, flags);
175 if (ret && p != ret)
176 kfree(p);
177
178 return ret;
179}
180EXPORT_SYMBOL(krealloc);
181
182/**
183 * kzfree - like kfree but zero memory
184 * @p: object to free memory of
185 *
186 * The memory of the object @p points to is zeroed before freed.
187 * If @p is %NULL, kzfree() does nothing.
188 *
189 * Note: this function zeroes the whole allocated buffer which can be a good
190 * deal bigger than the requested buffer size passed to kmalloc(). So be
191 * careful when using this function in performance sensitive code.
192 */
193void kzfree(const void *p)
194{
195 size_t ks;
196 void *mem = (void *)p;
197
198 if (unlikely(ZERO_OR_NULL_PTR(mem)))
199 return;
200 ks = ksize(mem);
201 memset(mem, 0, ks);
202 kfree(mem);
203}
204EXPORT_SYMBOL(kzfree);
205
206/*
207 * strndup_user - duplicate an existing string from user space
208 * @s: The string to duplicate
209 * @n: Maximum number of bytes to copy, including the trailing NUL.
210 */
211char *strndup_user(const char __user *s, long n)
212{
213 char *p;
214 long length;
215
216 length = strnlen_user(s, n);
217
218 if (!length)
219 return ERR_PTR(-EFAULT);
220
221 if (length > n)
222 return ERR_PTR(-EINVAL);
223
224 p = memdup_user(s, length);
225
226 if (IS_ERR(p))
227 return p;
228
229 p[length - 1] = '\0';
230
231 return p;
232}
233EXPORT_SYMBOL(strndup_user);
234
235void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
236 struct vm_area_struct *prev, struct rb_node *rb_parent)
237{
238 struct vm_area_struct *next;
239
240 vma->vm_prev = prev;
241 if (prev) {
242 next = prev->vm_next;
243 prev->vm_next = vma;
244 } else {
245 mm->mmap = vma;
246 if (rb_parent)
247 next = rb_entry(rb_parent,
248 struct vm_area_struct, vm_rb);
249 else
250 next = NULL;
251 }
252 vma->vm_next = next;
253 if (next)
254 next->vm_prev = vma;
255}
256
257/* Check if the vma is being used as a stack by this task */
258static int vm_is_stack_for_task(struct task_struct *t,
259 struct vm_area_struct *vma)
260{
261 return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
262}
263
264/*
265 * Check if the vma is being used as a stack.
266 * If is_group is non-zero, check in the entire thread group or else
267 * just check in the current task. Returns the pid of the task that
268 * the vma is stack for.
269 */
270pid_t vm_is_stack(struct task_struct *task,
271 struct vm_area_struct *vma, int in_group)
272{
273 pid_t ret = 0;
274
275 if (vm_is_stack_for_task(task, vma))
276 return task->pid;
277
278 if (in_group) {
279 struct task_struct *t;
280 rcu_read_lock();
281 if (!pid_alive(task))
282 goto done;
283
284 t = task;
285 do {
286 if (vm_is_stack_for_task(t, vma)) {
287 ret = t->pid;
288 goto done;
289 }
290 } while_each_thread(task, t);
291done:
292 rcu_read_unlock();
293 }
294
295 return ret;
296}
297
298#if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
299void arch_pick_mmap_layout(struct mm_struct *mm)
300{
301 mm->mmap_base = TASK_UNMAPPED_BASE;
302 mm->get_unmapped_area = arch_get_unmapped_area;
303}
304#endif
305
306/*
307 * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
308 * back to the regular GUP.
309 * If the architecture not support this function, simply return with no
310 * page pinned
311 */
312int __weak __get_user_pages_fast(unsigned long start,
313 int nr_pages, int write, struct page **pages)
314{
315 return 0;
316}
317EXPORT_SYMBOL_GPL(__get_user_pages_fast);
318
319/**
320 * get_user_pages_fast() - pin user pages in memory
321 * @start: starting user address
322 * @nr_pages: number of pages from start to pin
323 * @write: whether pages will be written to
324 * @pages: array that receives pointers to the pages pinned.
325 * Should be at least nr_pages long.
326 *
327 * Returns number of pages pinned. This may be fewer than the number
328 * requested. If nr_pages is 0 or negative, returns 0. If no pages
329 * were pinned, returns -errno.
330 *
331 * get_user_pages_fast provides equivalent functionality to get_user_pages,
332 * operating on current and current->mm, with force=0 and vma=NULL. However
333 * unlike get_user_pages, it must be called without mmap_sem held.
334 *
335 * get_user_pages_fast may take mmap_sem and page table locks, so no
336 * assumptions can be made about lack of locking. get_user_pages_fast is to be
337 * implemented in a way that is advantageous (vs get_user_pages()) when the
338 * user memory area is already faulted in and present in ptes. However if the
339 * pages have to be faulted in, it may turn out to be slightly slower so
340 * callers need to carefully consider what to use. On many architectures,
341 * get_user_pages_fast simply falls back to get_user_pages.
342 */
343int __weak get_user_pages_fast(unsigned long start,
344 int nr_pages, int write, struct page **pages)
345{
346 struct mm_struct *mm = current->mm;
347 int ret;
348
349 down_read(&mm->mmap_sem);
350 ret = get_user_pages(current, mm, start, nr_pages,
351 write, 0, pages, NULL);
352 up_read(&mm->mmap_sem);
353
354 return ret;
355}
356EXPORT_SYMBOL_GPL(get_user_pages_fast);
357
358unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
359 unsigned long len, unsigned long prot,
360 unsigned long flag, unsigned long pgoff)
361{
362 unsigned long ret;
363 struct mm_struct *mm = current->mm;
364 unsigned long populate;
365
366 ret = security_mmap_file(file, prot, flag);
367 if (!ret) {
368 down_write(&mm->mmap_sem);
369 ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
370 &populate);
371 up_write(&mm->mmap_sem);
372 if (populate)
373 mm_populate(ret, populate);
374 }
375 return ret;
376}
377
378unsigned long vm_mmap(struct file *file, unsigned long addr,
379 unsigned long len, unsigned long prot,
380 unsigned long flag, unsigned long offset)
381{
382 if (unlikely(offset + PAGE_ALIGN(len) < offset))
383 return -EINVAL;
384 if (unlikely(offset & ~PAGE_MASK))
385 return -EINVAL;
386
387 return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
388}
389EXPORT_SYMBOL(vm_mmap);
390
391void kvfree(const void *addr)
392{
393 if (is_vmalloc_addr(addr))
394 vfree(addr);
395 else
396 kfree(addr);
397}
398EXPORT_SYMBOL(kvfree);
399
400struct address_space *page_mapping(struct page *page)
401{
402 struct address_space *mapping = page->mapping;
403
404 /* This happens if someone calls flush_dcache_page on slab page */
405 if (unlikely(PageSlab(page)))
406 return NULL;
407
408 if (unlikely(PageSwapCache(page))) {
409 swp_entry_t entry;
410
411 entry.val = page_private(page);
412 mapping = swap_address_space(entry);
413 } else if ((unsigned long)mapping & PAGE_MAPPING_ANON)
414 mapping = NULL;
415 return mapping;
416}
417
418int overcommit_ratio_handler(struct ctl_table *table, int write,
419 void __user *buffer, size_t *lenp,
420 loff_t *ppos)
421{
422 int ret;
423
424 ret = proc_dointvec(table, write, buffer, lenp, ppos);
425 if (ret == 0 && write)
426 sysctl_overcommit_kbytes = 0;
427 return ret;
428}
429
430int overcommit_kbytes_handler(struct ctl_table *table, int write,
431 void __user *buffer, size_t *lenp,
432 loff_t *ppos)
433{
434 int ret;
435
436 ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
437 if (ret == 0 && write)
438 sysctl_overcommit_ratio = 0;
439 return ret;
440}
441
442/*
443 * Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
444 */
445unsigned long vm_commit_limit(void)
446{
447 unsigned long allowed;
448
449 if (sysctl_overcommit_kbytes)
450 allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10);
451 else
452 allowed = ((totalram_pages - hugetlb_total_pages())
453 * sysctl_overcommit_ratio / 100);
454 allowed += total_swap_pages;
455
456 return allowed;
457}
458
459/**
460 * get_cmdline() - copy the cmdline value to a buffer.
461 * @task: the task whose cmdline value to copy.
462 * @buffer: the buffer to copy to.
463 * @buflen: the length of the buffer. Larger cmdline values are truncated
464 * to this length.
465 * Returns the size of the cmdline field copied. Note that the copy does
466 * not guarantee an ending NULL byte.
467 */
468int get_cmdline(struct task_struct *task, char *buffer, int buflen)
469{
470 int res = 0;
471 unsigned int len;
472 struct mm_struct *mm = get_task_mm(task);
473 if (!mm)
474 goto out;
475 if (!mm->arg_end)
476 goto out_mm; /* Shh! No looking before we're done */
477
478 len = mm->arg_end - mm->arg_start;
479
480 if (len > buflen)
481 len = buflen;
482
483 res = access_process_vm(task, mm->arg_start, buffer, len, 0);
484
485 /*
486 * If the nul at the end of args has been overwritten, then
487 * assume application is using setproctitle(3).
488 */
489 if (res > 0 && buffer[res-1] != '\0' && len < buflen) {
490 len = strnlen(buffer, res);
491 if (len < res) {
492 res = len;
493 } else {
494 len = mm->env_end - mm->env_start;
495 if (len > buflen - res)
496 len = buflen - res;
497 res += access_process_vm(task, mm->env_start,
498 buffer+res, len, 0);
499 res = strnlen(buffer, res);
500 }
501 }
502out_mm:
503 mmput(mm);
504out:
505 return res;
506}
507
508/* Tracepoints definitions. */
509EXPORT_TRACEPOINT_SYMBOL(kmalloc);
510EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
511EXPORT_TRACEPOINT_SYMBOL(kmalloc_node);
512EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node);
513EXPORT_TRACEPOINT_SYMBOL(kfree);
514EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);