projects/linux·blob v4.10 · refs

1928 lines · 44.4 KiB

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 <linux/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 unsigned int gup_flags = FOLL_FORCE;
195
196#ifdef CONFIG_STACK_GROWSUP
197 if (write) {
198 ret = expand_downwards(bprm->vma, pos);
199 if (ret < 0)
200 return NULL;
201 }
202#endif
203
204 if (write)
205 gup_flags |= FOLL_WRITE;
206
207 /*
208 * We are doing an exec(). 'current' is the process
209 * doing the exec and bprm->mm is the new process's mm.
210 */
211 ret = get_user_pages_remote(current, bprm->mm, pos, 1, gup_flags,
212 &page, NULL, NULL);
213 if (ret <= 0)
214 return NULL;
215
216 if (write) {
217 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
218 struct rlimit *rlim;
219
220 acct_arg_size(bprm, size / PAGE_SIZE);
221
222 /*
223 * We've historically supported up to 32 pages (ARG_MAX)
224 * of argument strings even with small stacks
225 */
226 if (size <= ARG_MAX)
227 return page;
228
229 /*
230 * Limit to 1/4-th the stack size for the argv+env strings.
231 * This ensures that:
232 * - the remaining binfmt code will not run out of stack space,
233 * - the program will have a reasonable amount of stack left
234 * to work from.
235 */
236 rlim = current->signal->rlim;
237 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
238 put_page(page);
239 return NULL;
240 }
241 }
242
243 return page;
244}
245
246static void put_arg_page(struct page *page)
247{
248 put_page(page);
249}
250
251static void free_arg_pages(struct linux_binprm *bprm)
252{
253}
254
255static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
256 struct page *page)
257{
258 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
259}
260
261static int __bprm_mm_init(struct linux_binprm *bprm)
262{
263 int err;
264 struct vm_area_struct *vma = NULL;
265 struct mm_struct *mm = bprm->mm;
266
267 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
268 if (!vma)
269 return -ENOMEM;
270
271 if (down_write_killable(&mm->mmap_sem)) {
272 err = -EINTR;
273 goto err_free;
274 }
275 vma->vm_mm = mm;
276
277 /*
278 * Place the stack at the largest stack address the architecture
279 * supports. Later, we'll move this to an appropriate place. We don't
280 * use STACK_TOP because that can depend on attributes which aren't
281 * configured yet.
282 */
283 BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
284 vma->vm_end = STACK_TOP_MAX;
285 vma->vm_start = vma->vm_end - PAGE_SIZE;
286 vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
287 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
288 INIT_LIST_HEAD(&vma->anon_vma_chain);
289
290 err = insert_vm_struct(mm, vma);
291 if (err)
292 goto err;
293
294 mm->stack_vm = mm->total_vm = 1;
295 arch_bprm_mm_init(mm, vma);
296 up_write(&mm->mmap_sem);
297 bprm->p = vma->vm_end - sizeof(void *);
298 return 0;
299err:
300 up_write(&mm->mmap_sem);
301err_free:
302 bprm->vma = NULL;
303 kmem_cache_free(vm_area_cachep, vma);
304 return err;
305}
306
307static bool valid_arg_len(struct linux_binprm *bprm, long len)
308{
309 return len <= MAX_ARG_STRLEN;
310}
311
312#else
313
314static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
315{
316}
317
318static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
319 int write)
320{
321 struct page *page;
322
323 page = bprm->page[pos / PAGE_SIZE];
324 if (!page && write) {
325 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
326 if (!page)
327 return NULL;
328 bprm->page[pos / PAGE_SIZE] = page;
329 }
330
331 return page;
332}
333
334static void put_arg_page(struct page *page)
335{
336}
337
338static void free_arg_page(struct linux_binprm *bprm, int i)
339{
340 if (bprm->page[i]) {
341 __free_page(bprm->page[i]);
342 bprm->page[i] = NULL;
343 }
344}
345
346static void free_arg_pages(struct linux_binprm *bprm)
347{
348 int i;
349
350 for (i = 0; i < MAX_ARG_PAGES; i++)
351 free_arg_page(bprm, i);
352}
353
354static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
355 struct page *page)
356{
357}
358
359static int __bprm_mm_init(struct linux_binprm *bprm)
360{
361 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
362 return 0;
363}
364
365static bool valid_arg_len(struct linux_binprm *bprm, long len)
366{
367 return len <= bprm->p;
368}
369
370#endif /* CONFIG_MMU */
371
372/*
373 * Create a new mm_struct and populate it with a temporary stack
374 * vm_area_struct. We don't have enough context at this point to set the stack
375 * flags, permissions, and offset, so we use temporary values. We'll update
376 * them later in setup_arg_pages().
377 */
378static int bprm_mm_init(struct linux_binprm *bprm)
379{
380 int err;
381 struct mm_struct *mm = NULL;
382
383 bprm->mm = mm = mm_alloc();
384 err = -ENOMEM;
385 if (!mm)
386 goto err;
387
388 err = __bprm_mm_init(bprm);
389 if (err)
390 goto err;
391
392 return 0;
393
394err:
395 if (mm) {
396 bprm->mm = NULL;
397 mmdrop(mm);
398 }
399
400 return err;
401}
402
403struct user_arg_ptr {
404#ifdef CONFIG_COMPAT
405 bool is_compat;
406#endif
407 union {
408 const char __user *const __user *native;
409#ifdef CONFIG_COMPAT
410 const compat_uptr_t __user *compat;
411#endif
412 } ptr;
413};
414
415static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
416{
417 const char __user *native;
418
419#ifdef CONFIG_COMPAT
420 if (unlikely(argv.is_compat)) {
421 compat_uptr_t compat;
422
423 if (get_user(compat, argv.ptr.compat + nr))
424 return ERR_PTR(-EFAULT);
425
426 return compat_ptr(compat);
427 }
428#endif
429
430 if (get_user(native, argv.ptr.native + nr))
431 return ERR_PTR(-EFAULT);
432
433 return native;
434}
435
436/*
437 * count() counts the number of strings in array ARGV.
438 */
439static int count(struct user_arg_ptr argv, int max)
440{
441 int i = 0;
442
443 if (argv.ptr.native != NULL) {
444 for (;;) {
445 const char __user *p = get_user_arg_ptr(argv, i);
446
447 if (!p)
448 break;
449
450 if (IS_ERR(p))
451 return -EFAULT;
452
453 if (i >= max)
454 return -E2BIG;
455 ++i;
456
457 if (fatal_signal_pending(current))
458 return -ERESTARTNOHAND;
459 cond_resched();
460 }
461 }
462 return i;
463}
464
465/*
466 * 'copy_strings()' copies argument/environment strings from the old
467 * processes's memory to the new process's stack. The call to get_user_pages()
468 * ensures the destination page is created and not swapped out.
469 */
470static int copy_strings(int argc, struct user_arg_ptr argv,
471 struct linux_binprm *bprm)
472{
473 struct page *kmapped_page = NULL;
474 char *kaddr = NULL;
475 unsigned long kpos = 0;
476 int ret;
477
478 while (argc-- > 0) {
479 const char __user *str;
480 int len;
481 unsigned long pos;
482
483 ret = -EFAULT;
484 str = get_user_arg_ptr(argv, argc);
485 if (IS_ERR(str))
486 goto out;
487
488 len = strnlen_user(str, MAX_ARG_STRLEN);
489 if (!len)
490 goto out;
491
492 ret = -E2BIG;
493 if (!valid_arg_len(bprm, len))
494 goto out;
495
496 /* We're going to work our way backwords. */
497 pos = bprm->p;
498 str += len;
499 bprm->p -= len;
500
501 while (len > 0) {
502 int offset, bytes_to_copy;
503
504 if (fatal_signal_pending(current)) {
505 ret = -ERESTARTNOHAND;
506 goto out;
507 }
508 cond_resched();
509
510 offset = pos % PAGE_SIZE;
511 if (offset == 0)
512 offset = PAGE_SIZE;
513
514 bytes_to_copy = offset;
515 if (bytes_to_copy > len)
516 bytes_to_copy = len;
517
518 offset -= bytes_to_copy;
519 pos -= bytes_to_copy;
520 str -= bytes_to_copy;
521 len -= bytes_to_copy;
522
523 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
524 struct page *page;
525
526 page = get_arg_page(bprm, pos, 1);
527 if (!page) {
528 ret = -E2BIG;
529 goto out;
530 }
531
532 if (kmapped_page) {
533 flush_kernel_dcache_page(kmapped_page);
534 kunmap(kmapped_page);
535 put_arg_page(kmapped_page);
536 }
537 kmapped_page = page;
538 kaddr = kmap(kmapped_page);
539 kpos = pos & PAGE_MASK;
540 flush_arg_page(bprm, kpos, kmapped_page);
541 }
542 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
543 ret = -EFAULT;
544 goto out;
545 }
546 }
547 }
548 ret = 0;
549out:
550 if (kmapped_page) {
551 flush_kernel_dcache_page(kmapped_page);
552 kunmap(kmapped_page);
553 put_arg_page(kmapped_page);
554 }
555 return ret;
556}
557
558/*
559 * Like copy_strings, but get argv and its values from kernel memory.
560 */
561int copy_strings_kernel(int argc, const char *const *__argv,
562 struct linux_binprm *bprm)
563{
564 int r;
565 mm_segment_t oldfs = get_fs();
566 struct user_arg_ptr argv = {
567 .ptr.native = (const char __user *const __user *)__argv,
568 };
569
570 set_fs(KERNEL_DS);
571 r = copy_strings(argc, argv, bprm);
572 set_fs(oldfs);
573
574 return r;
575}
576EXPORT_SYMBOL(copy_strings_kernel);
577
578#ifdef CONFIG_MMU
579
580/*
581 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
582 * the binfmt code determines where the new stack should reside, we shift it to
583 * its final location. The process proceeds as follows:
584 *
585 * 1) Use shift to calculate the new vma endpoints.
586 * 2) Extend vma to cover both the old and new ranges. This ensures the
587 * arguments passed to subsequent functions are consistent.
588 * 3) Move vma's page tables to the new range.
589 * 4) Free up any cleared pgd range.
590 * 5) Shrink the vma to cover only the new range.
591 */
592static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
593{
594 struct mm_struct *mm = vma->vm_mm;
595 unsigned long old_start = vma->vm_start;
596 unsigned long old_end = vma->vm_end;
597 unsigned long length = old_end - old_start;
598 unsigned long new_start = old_start - shift;
599 unsigned long new_end = old_end - shift;
600 struct mmu_gather tlb;
601
602 BUG_ON(new_start > new_end);
603
604 /*
605 * ensure there are no vmas between where we want to go
606 * and where we are
607 */
608 if (vma != find_vma(mm, new_start))
609 return -EFAULT;
610
611 /*
612 * cover the whole range: [new_start, old_end)
613 */
614 if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
615 return -ENOMEM;
616
617 /*
618 * move the page tables downwards, on failure we rely on
619 * process cleanup to remove whatever mess we made.
620 */
621 if (length != move_page_tables(vma, old_start,
622 vma, new_start, length, false))
623 return -ENOMEM;
624
625 lru_add_drain();
626 tlb_gather_mmu(&tlb, mm, old_start, old_end);
627 if (new_end > old_start) {
628 /*
629 * when the old and new regions overlap clear from new_end.
630 */
631 free_pgd_range(&tlb, new_end, old_end, new_end,
632 vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
633 } else {
634 /*
635 * otherwise, clean from old_start; this is done to not touch
636 * the address space in [new_end, old_start) some architectures
637 * have constraints on va-space that make this illegal (IA64) -
638 * for the others its just a little faster.
639 */
640 free_pgd_range(&tlb, old_start, old_end, new_end,
641 vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
642 }
643 tlb_finish_mmu(&tlb, old_start, old_end);
644
645 /*
646 * Shrink the vma to just the new range. Always succeeds.
647 */
648 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
649
650 return 0;
651}
652
653/*
654 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
655 * the stack is optionally relocated, and some extra space is added.
656 */
657int setup_arg_pages(struct linux_binprm *bprm,
658 unsigned long stack_top,
659 int executable_stack)
660{
661 unsigned long ret;
662 unsigned long stack_shift;
663 struct mm_struct *mm = current->mm;
664 struct vm_area_struct *vma = bprm->vma;
665 struct vm_area_struct *prev = NULL;
666 unsigned long vm_flags;
667 unsigned long stack_base;
668 unsigned long stack_size;
669 unsigned long stack_expand;
670 unsigned long rlim_stack;
671
672#ifdef CONFIG_STACK_GROWSUP
673 /* Limit stack size */
674 stack_base = rlimit_max(RLIMIT_STACK);
675 if (stack_base > STACK_SIZE_MAX)
676 stack_base = STACK_SIZE_MAX;
677
678 /* Add space for stack randomization. */
679 stack_base += (STACK_RND_MASK << PAGE_SHIFT);
680
681 /* Make sure we didn't let the argument array grow too large. */
682 if (vma->vm_end - vma->vm_start > stack_base)
683 return -ENOMEM;
684
685 stack_base = PAGE_ALIGN(stack_top - stack_base);
686
687 stack_shift = vma->vm_start - stack_base;
688 mm->arg_start = bprm->p - stack_shift;
689 bprm->p = vma->vm_end - stack_shift;
690#else
691 stack_top = arch_align_stack(stack_top);
692 stack_top = PAGE_ALIGN(stack_top);
693
694 if (unlikely(stack_top < mmap_min_addr) ||
695 unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
696 return -ENOMEM;
697
698 stack_shift = vma->vm_end - stack_top;
699
700 bprm->p -= stack_shift;
701 mm->arg_start = bprm->p;
702#endif
703
704 if (bprm->loader)
705 bprm->loader -= stack_shift;
706 bprm->exec -= stack_shift;
707
708 if (down_write_killable(&mm->mmap_sem))
709 return -EINTR;
710
711 vm_flags = VM_STACK_FLAGS;
712
713 /*
714 * Adjust stack execute permissions; explicitly enable for
715 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
716 * (arch default) otherwise.
717 */
718 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
719 vm_flags |= VM_EXEC;
720 else if (executable_stack == EXSTACK_DISABLE_X)
721 vm_flags &= ~VM_EXEC;
722 vm_flags |= mm->def_flags;
723 vm_flags |= VM_STACK_INCOMPLETE_SETUP;
724
725 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
726 vm_flags);
727 if (ret)
728 goto out_unlock;
729 BUG_ON(prev != vma);
730
731 /* Move stack pages down in memory. */
732 if (stack_shift) {
733 ret = shift_arg_pages(vma, stack_shift);
734 if (ret)
735 goto out_unlock;
736 }
737
738 /* mprotect_fixup is overkill to remove the temporary stack flags */
739 vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
740
741 stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
742 stack_size = vma->vm_end - vma->vm_start;
743 /*
744 * Align this down to a page boundary as expand_stack
745 * will align it up.
746 */
747 rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
748#ifdef CONFIG_STACK_GROWSUP
749 if (stack_size + stack_expand > rlim_stack)
750 stack_base = vma->vm_start + rlim_stack;
751 else
752 stack_base = vma->vm_end + stack_expand;
753#else
754 if (stack_size + stack_expand > rlim_stack)
755 stack_base = vma->vm_end - rlim_stack;
756 else
757 stack_base = vma->vm_start - stack_expand;
758#endif
759 current->mm->start_stack = bprm->p;
760 ret = expand_stack(vma, stack_base);
761 if (ret)
762 ret = -EFAULT;
763
764out_unlock:
765 up_write(&mm->mmap_sem);
766 return ret;
767}
768EXPORT_SYMBOL(setup_arg_pages);
769
770#else
771
772/*
773 * Transfer the program arguments and environment from the holding pages
774 * onto the stack. The provided stack pointer is adjusted accordingly.
775 */
776int transfer_args_to_stack(struct linux_binprm *bprm,
777 unsigned long *sp_location)
778{
779 unsigned long index, stop, sp;
780 int ret = 0;
781
782 stop = bprm->p >> PAGE_SHIFT;
783 sp = *sp_location;
784
785 for (index = MAX_ARG_PAGES - 1; index >= stop; index--) {
786 unsigned int offset = index == stop ? bprm->p & ~PAGE_MASK : 0;
787 char *src = kmap(bprm->page[index]) + offset;
788 sp -= PAGE_SIZE - offset;
789 if (copy_to_user((void *) sp, src, PAGE_SIZE - offset) != 0)
790 ret = -EFAULT;
791 kunmap(bprm->page[index]);
792 if (ret)
793 goto out;
794 }
795
796 *sp_location = sp;
797
798out:
799 return ret;
800}
801EXPORT_SYMBOL(transfer_args_to_stack);
802
803#endif /* CONFIG_MMU */
804
805static struct file *do_open_execat(int fd, struct filename *name, int flags)
806{
807 struct file *file;
808 int err;
809 struct open_flags open_exec_flags = {
810 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
811 .acc_mode = MAY_EXEC,
812 .intent = LOOKUP_OPEN,
813 .lookup_flags = LOOKUP_FOLLOW,
814 };
815
816 if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
817 return ERR_PTR(-EINVAL);
818 if (flags & AT_SYMLINK_NOFOLLOW)
819 open_exec_flags.lookup_flags &= ~LOOKUP_FOLLOW;
820 if (flags & AT_EMPTY_PATH)
821 open_exec_flags.lookup_flags |= LOOKUP_EMPTY;
822
823 file = do_filp_open(fd, name, &open_exec_flags);
824 if (IS_ERR(file))
825 goto out;
826
827 err = -EACCES;
828 if (!S_ISREG(file_inode(file)->i_mode))
829 goto exit;
830
831 if (path_noexec(&file->f_path))
832 goto exit;
833
834 err = deny_write_access(file);
835 if (err)
836 goto exit;
837
838 if (name->name[0] != '\0')
839 fsnotify_open(file);
840
841out:
842 return file;
843
844exit:
845 fput(file);
846 return ERR_PTR(err);
847}
848
849struct file *open_exec(const char *name)
850{
851 struct filename *filename = getname_kernel(name);
852 struct file *f = ERR_CAST(filename);
853
854 if (!IS_ERR(filename)) {
855 f = do_open_execat(AT_FDCWD, filename, 0);
856 putname(filename);
857 }
858 return f;
859}
860EXPORT_SYMBOL(open_exec);
861
862int kernel_read(struct file *file, loff_t offset,
863 char *addr, unsigned long count)
864{
865 mm_segment_t old_fs;
866 loff_t pos = offset;
867 int result;
868
869 old_fs = get_fs();
870 set_fs(get_ds());
871 /* The cast to a user pointer is valid due to the set_fs() */
872 result = vfs_read(file, (void __user *)addr, count, &pos);
873 set_fs(old_fs);
874 return result;
875}
876
877EXPORT_SYMBOL(kernel_read);
878
879int kernel_read_file(struct file *file, void **buf, loff_t *size,
880 loff_t max_size, enum kernel_read_file_id id)
881{
882 loff_t i_size, pos;
883 ssize_t bytes = 0;
884 int ret;
885
886 if (!S_ISREG(file_inode(file)->i_mode) || max_size < 0)
887 return -EINVAL;
888
889 ret = security_kernel_read_file(file, id);
890 if (ret)
891 return ret;
892
893 ret = deny_write_access(file);
894 if (ret)
895 return ret;
896
897 i_size = i_size_read(file_inode(file));
898 if (max_size > 0 && i_size > max_size) {
899 ret = -EFBIG;
900 goto out;
901 }
902 if (i_size <= 0) {
903 ret = -EINVAL;
904 goto out;
905 }
906
907 if (id != READING_FIRMWARE_PREALLOC_BUFFER)
908 *buf = vmalloc(i_size);
909 if (!*buf) {
910 ret = -ENOMEM;
911 goto out;
912 }
913
914 pos = 0;
915 while (pos < i_size) {
916 bytes = kernel_read(file, pos, (char *)(*buf) + pos,
917 i_size - pos);
918 if (bytes < 0) {
919 ret = bytes;
920 goto out;
921 }
922
923 if (bytes == 0)
924 break;
925 pos += bytes;
926 }
927
928 if (pos != i_size) {
929 ret = -EIO;
930 goto out_free;
931 }
932
933 ret = security_kernel_post_read_file(file, *buf, i_size, id);
934 if (!ret)
935 *size = pos;
936
937out_free:
938 if (ret < 0) {
939 if (id != READING_FIRMWARE_PREALLOC_BUFFER) {
940 vfree(*buf);
941 *buf = NULL;
942 }
943 }
944
945out:
946 allow_write_access(file);
947 return ret;
948}
949EXPORT_SYMBOL_GPL(kernel_read_file);
950
951int kernel_read_file_from_path(char *path, void **buf, loff_t *size,
952 loff_t max_size, enum kernel_read_file_id id)
953{
954 struct file *file;
955 int ret;
956
957 if (!path || !*path)
958 return -EINVAL;
959
960 file = filp_open(path, O_RDONLY, 0);
961 if (IS_ERR(file))
962 return PTR_ERR(file);
963
964 ret = kernel_read_file(file, buf, size, max_size, id);
965 fput(file);
966 return ret;
967}
968EXPORT_SYMBOL_GPL(kernel_read_file_from_path);
969
970int kernel_read_file_from_fd(int fd, void **buf, loff_t *size, loff_t max_size,
971 enum kernel_read_file_id id)
972{
973 struct fd f = fdget(fd);
974 int ret = -EBADF;
975
976 if (!f.file)
977 goto out;
978
979 ret = kernel_read_file(f.file, buf, size, max_size, id);
980out:
981 fdput(f);
982 return ret;
983}
984EXPORT_SYMBOL_GPL(kernel_read_file_from_fd);
985
986ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
987{
988 ssize_t res = vfs_read(file, (void __user *)addr, len, &pos);
989 if (res > 0)
990 flush_icache_range(addr, addr + len);
991 return res;
992}
993EXPORT_SYMBOL(read_code);
994
995static int exec_mmap(struct mm_struct *mm)
996{
997 struct task_struct *tsk;
998 struct mm_struct *old_mm, *active_mm;
999
1000 /* Notify parent that we're no longer interested in the old VM */
1001 tsk = current;
1002 old_mm = current->mm;
1003 mm_release(tsk, old_mm);
1004
1005 if (old_mm) {
1006 sync_mm_rss(old_mm);
1007 /*
1008 * Make sure that if there is a core dump in progress
1009 * for the old mm, we get out and die instead of going
1010 * through with the exec. We must hold mmap_sem around
1011 * checking core_state and changing tsk->mm.
1012 */
1013 down_read(&old_mm->mmap_sem);
1014 if (unlikely(old_mm->core_state)) {
1015 up_read(&old_mm->mmap_sem);
1016 return -EINTR;
1017 }
1018 }
1019 task_lock(tsk);
1020 active_mm = tsk->active_mm;
1021 tsk->mm = mm;
1022 tsk->active_mm = mm;
1023 activate_mm(active_mm, mm);
1024 tsk->mm->vmacache_seqnum = 0;
1025 vmacache_flush(tsk);
1026 task_unlock(tsk);
1027 if (old_mm) {
1028 up_read(&old_mm->mmap_sem);
1029 BUG_ON(active_mm != old_mm);
1030 setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
1031 mm_update_next_owner(old_mm);
1032 mmput(old_mm);
1033 return 0;
1034 }
1035 mmdrop(active_mm);
1036 return 0;
1037}
1038
1039/*
1040 * This function makes sure the current process has its own signal table,
1041 * so that flush_signal_handlers can later reset the handlers without
1042 * disturbing other processes. (Other processes might share the signal
1043 * table via the CLONE_SIGHAND option to clone().)
1044 */
1045static int de_thread(struct task_struct *tsk)
1046{
1047 struct signal_struct *sig = tsk->signal;
1048 struct sighand_struct *oldsighand = tsk->sighand;
1049 spinlock_t *lock = &oldsighand->siglock;
1050
1051 if (thread_group_empty(tsk))
1052 goto no_thread_group;
1053
1054 /*
1055 * Kill all other threads in the thread group.
1056 */
1057 spin_lock_irq(lock);
1058 if (signal_group_exit(sig)) {
1059 /*
1060 * Another group action in progress, just
1061 * return so that the signal is processed.
1062 */
1063 spin_unlock_irq(lock);
1064 return -EAGAIN;
1065 }
1066
1067 sig->group_exit_task = tsk;
1068 sig->notify_count = zap_other_threads(tsk);
1069 if (!thread_group_leader(tsk))
1070 sig->notify_count--;
1071
1072 while (sig->notify_count) {
1073 __set_current_state(TASK_KILLABLE);
1074 spin_unlock_irq(lock);
1075 schedule();
1076 if (unlikely(__fatal_signal_pending(tsk)))
1077 goto killed;
1078 spin_lock_irq(lock);
1079 }
1080 spin_unlock_irq(lock);
1081
1082 /*
1083 * At this point all other threads have exited, all we have to
1084 * do is to wait for the thread group leader to become inactive,
1085 * and to assume its PID:
1086 */
1087 if (!thread_group_leader(tsk)) {
1088 struct task_struct *leader = tsk->group_leader;
1089
1090 for (;;) {
1091 threadgroup_change_begin(tsk);
1092 write_lock_irq(&tasklist_lock);
1093 /*
1094 * Do this under tasklist_lock to ensure that
1095 * exit_notify() can't miss ->group_exit_task
1096 */
1097 sig->notify_count = -1;
1098 if (likely(leader->exit_state))
1099 break;
1100 __set_current_state(TASK_KILLABLE);
1101 write_unlock_irq(&tasklist_lock);
1102 threadgroup_change_end(tsk);
1103 schedule();
1104 if (unlikely(__fatal_signal_pending(tsk)))
1105 goto killed;
1106 }
1107
1108 /*
1109 * The only record we have of the real-time age of a
1110 * process, regardless of execs it's done, is start_time.
1111 * All the past CPU time is accumulated in signal_struct
1112 * from sister threads now dead. But in this non-leader
1113 * exec, nothing survives from the original leader thread,
1114 * whose birth marks the true age of this process now.
1115 * When we take on its identity by switching to its PID, we
1116 * also take its birthdate (always earlier than our own).
1117 */
1118 tsk->start_time = leader->start_time;
1119 tsk->real_start_time = leader->real_start_time;
1120
1121 BUG_ON(!same_thread_group(leader, tsk));
1122 BUG_ON(has_group_leader_pid(tsk));
1123 /*
1124 * An exec() starts a new thread group with the
1125 * TGID of the previous thread group. Rehash the
1126 * two threads with a switched PID, and release
1127 * the former thread group leader:
1128 */
1129
1130 /* Become a process group leader with the old leader's pid.
1131 * The old leader becomes a thread of the this thread group.
1132 * Note: The old leader also uses this pid until release_task
1133 * is called. Odd but simple and correct.
1134 */
1135 tsk->pid = leader->pid;
1136 change_pid(tsk, PIDTYPE_PID, task_pid(leader));
1137 transfer_pid(leader, tsk, PIDTYPE_PGID);
1138 transfer_pid(leader, tsk, PIDTYPE_SID);
1139
1140 list_replace_rcu(&leader->tasks, &tsk->tasks);
1141 list_replace_init(&leader->sibling, &tsk->sibling);
1142
1143 tsk->group_leader = tsk;
1144 leader->group_leader = tsk;
1145
1146 tsk->exit_signal = SIGCHLD;
1147 leader->exit_signal = -1;
1148
1149 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
1150 leader->exit_state = EXIT_DEAD;
1151
1152 /*
1153 * We are going to release_task()->ptrace_unlink() silently,
1154 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
1155 * the tracer wont't block again waiting for this thread.
1156 */
1157 if (unlikely(leader->ptrace))
1158 __wake_up_parent(leader, leader->parent);
1159 write_unlock_irq(&tasklist_lock);
1160 threadgroup_change_end(tsk);
1161
1162 release_task(leader);
1163 }
1164
1165 sig->group_exit_task = NULL;
1166 sig->notify_count = 0;
1167
1168no_thread_group:
1169 /* we have changed execution domain */
1170 tsk->exit_signal = SIGCHLD;
1171
1172#ifdef CONFIG_POSIX_TIMERS
1173 exit_itimers(sig);
1174 flush_itimer_signals();
1175#endif
1176
1177 if (atomic_read(&oldsighand->count) != 1) {
1178 struct sighand_struct *newsighand;
1179 /*
1180 * This ->sighand is shared with the CLONE_SIGHAND
1181 * but not CLONE_THREAD task, switch to the new one.
1182 */
1183 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1184 if (!newsighand)
1185 return -ENOMEM;
1186
1187 atomic_set(&newsighand->count, 1);
1188 memcpy(newsighand->action, oldsighand->action,
1189 sizeof(newsighand->action));
1190
1191 write_lock_irq(&tasklist_lock);
1192 spin_lock(&oldsighand->siglock);
1193 rcu_assign_pointer(tsk->sighand, newsighand);
1194 spin_unlock(&oldsighand->siglock);
1195 write_unlock_irq(&tasklist_lock);
1196
1197 __cleanup_sighand(oldsighand);
1198 }
1199
1200 BUG_ON(!thread_group_leader(tsk));
1201 return 0;
1202
1203killed:
1204 /* protects against exit_notify() and __exit_signal() */
1205 read_lock(&tasklist_lock);
1206 sig->group_exit_task = NULL;
1207 sig->notify_count = 0;
1208 read_unlock(&tasklist_lock);
1209 return -EAGAIN;
1210}
1211
1212char *get_task_comm(char *buf, struct task_struct *tsk)
1213{
1214 /* buf must be at least sizeof(tsk->comm) in size */
1215 task_lock(tsk);
1216 strncpy(buf, tsk->comm, sizeof(tsk->comm));
1217 task_unlock(tsk);
1218 return buf;
1219}
1220EXPORT_SYMBOL_GPL(get_task_comm);
1221
1222/*
1223 * These functions flushes out all traces of the currently running executable
1224 * so that a new one can be started
1225 */
1226
1227void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
1228{
1229 task_lock(tsk);
1230 trace_task_rename(tsk, buf);
1231 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1232 task_unlock(tsk);
1233 perf_event_comm(tsk, exec);
1234}
1235
1236int flush_old_exec(struct linux_binprm * bprm)
1237{
1238 int retval;
1239
1240 /*
1241 * Make sure we have a private signal table and that
1242 * we are unassociated from the previous thread group.
1243 */
1244 retval = de_thread(current);
1245 if (retval)
1246 goto out;
1247
1248 /*
1249 * Must be called _before_ exec_mmap() as bprm->mm is
1250 * not visibile until then. This also enables the update
1251 * to be lockless.
1252 */
1253 set_mm_exe_file(bprm->mm, bprm->file);
1254
1255 /*
1256 * Release all of the old mmap stuff
1257 */
1258 acct_arg_size(bprm, 0);
1259 retval = exec_mmap(bprm->mm);
1260 if (retval)
1261 goto out;
1262
1263 bprm->mm = NULL; /* We're using it now */
1264
1265 set_fs(USER_DS);
1266 current->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD |
1267 PF_NOFREEZE | PF_NO_SETAFFINITY);
1268 flush_thread();
1269 current->personality &= ~bprm->per_clear;
1270
1271 /*
1272 * We have to apply CLOEXEC before we change whether the process is
1273 * dumpable (in setup_new_exec) to avoid a race with a process in userspace
1274 * trying to access the should-be-closed file descriptors of a process
1275 * undergoing exec(2).
1276 */
1277 do_close_on_exec(current->files);
1278 return 0;
1279
1280out:
1281 return retval;
1282}
1283EXPORT_SYMBOL(flush_old_exec);
1284
1285void would_dump(struct linux_binprm *bprm, struct file *file)
1286{
1287 struct inode *inode = file_inode(file);
1288 if (inode_permission(inode, MAY_READ) < 0) {
1289 struct user_namespace *old, *user_ns;
1290 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1291
1292 /* Ensure mm->user_ns contains the executable */
1293 user_ns = old = bprm->mm->user_ns;
1294 while ((user_ns != &init_user_ns) &&
1295 !privileged_wrt_inode_uidgid(user_ns, inode))
1296 user_ns = user_ns->parent;
1297
1298 if (old != user_ns) {
1299 bprm->mm->user_ns = get_user_ns(user_ns);
1300 put_user_ns(old);
1301 }
1302 }
1303}
1304EXPORT_SYMBOL(would_dump);
1305
1306void setup_new_exec(struct linux_binprm * bprm)
1307{
1308 arch_pick_mmap_layout(current->mm);
1309
1310 /* This is the point of no return */
1311 current->sas_ss_sp = current->sas_ss_size = 0;
1312
1313 if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid()))
1314 set_dumpable(current->mm, SUID_DUMP_USER);
1315 else
1316 set_dumpable(current->mm, suid_dumpable);
1317
1318 perf_event_exec();
1319 __set_task_comm(current, kbasename(bprm->filename), true);
1320
1321 /* Set the new mm task size. We have to do that late because it may
1322 * depend on TIF_32BIT which is only updated in flush_thread() on
1323 * some architectures like powerpc
1324 */
1325 current->mm->task_size = TASK_SIZE;
1326
1327 /* install the new credentials */
1328 if (!uid_eq(bprm->cred->uid, current_euid()) ||
1329 !gid_eq(bprm->cred->gid, current_egid())) {
1330 current->pdeath_signal = 0;
1331 } else {
1332 if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
1333 set_dumpable(current->mm, suid_dumpable);
1334 }
1335
1336 /* An exec changes our domain. We are no longer part of the thread
1337 group */
1338 current->self_exec_id++;
1339 flush_signal_handlers(current, 0);
1340}
1341EXPORT_SYMBOL(setup_new_exec);
1342
1343/*
1344 * Prepare credentials and lock ->cred_guard_mutex.
1345 * install_exec_creds() commits the new creds and drops the lock.
1346 * Or, if exec fails before, free_bprm() should release ->cred and
1347 * and unlock.
1348 */
1349int prepare_bprm_creds(struct linux_binprm *bprm)
1350{
1351 if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1352 return -ERESTARTNOINTR;
1353
1354 bprm->cred = prepare_exec_creds();
1355 if (likely(bprm->cred))
1356 return 0;
1357
1358 mutex_unlock(&current->signal->cred_guard_mutex);
1359 return -ENOMEM;
1360}
1361
1362static void free_bprm(struct linux_binprm *bprm)
1363{
1364 free_arg_pages(bprm);
1365 if (bprm->cred) {
1366 mutex_unlock(&current->signal->cred_guard_mutex);
1367 abort_creds(bprm->cred);
1368 }
1369 if (bprm->file) {
1370 allow_write_access(bprm->file);
1371 fput(bprm->file);
1372 }
1373 /* If a binfmt changed the interp, free it. */
1374 if (bprm->interp != bprm->filename)
1375 kfree(bprm->interp);
1376 kfree(bprm);
1377}
1378
1379int bprm_change_interp(char *interp, struct linux_binprm *bprm)
1380{
1381 /* If a binfmt changed the interp, free it first. */
1382 if (bprm->interp != bprm->filename)
1383 kfree(bprm->interp);
1384 bprm->interp = kstrdup(interp, GFP_KERNEL);
1385 if (!bprm->interp)
1386 return -ENOMEM;
1387 return 0;
1388}
1389EXPORT_SYMBOL(bprm_change_interp);
1390
1391/*
1392 * install the new credentials for this executable
1393 */
1394void install_exec_creds(struct linux_binprm *bprm)
1395{
1396 security_bprm_committing_creds(bprm);
1397
1398 commit_creds(bprm->cred);
1399 bprm->cred = NULL;
1400
1401 /*
1402 * Disable monitoring for regular users
1403 * when executing setuid binaries. Must
1404 * wait until new credentials are committed
1405 * by commit_creds() above
1406 */
1407 if (get_dumpable(current->mm) != SUID_DUMP_USER)
1408 perf_event_exit_task(current);
1409 /*
1410 * cred_guard_mutex must be held at least to this point to prevent
1411 * ptrace_attach() from altering our determination of the task's
1412 * credentials; any time after this it may be unlocked.
1413 */
1414 security_bprm_committed_creds(bprm);
1415 mutex_unlock(&current->signal->cred_guard_mutex);
1416}
1417EXPORT_SYMBOL(install_exec_creds);
1418
1419/*
1420 * determine how safe it is to execute the proposed program
1421 * - the caller must hold ->cred_guard_mutex to protect against
1422 * PTRACE_ATTACH or seccomp thread-sync
1423 */
1424static void check_unsafe_exec(struct linux_binprm *bprm)
1425{
1426 struct task_struct *p = current, *t;
1427 unsigned n_fs;
1428
1429 if (p->ptrace) {
1430 if (ptracer_capable(p, current_user_ns()))
1431 bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP;
1432 else
1433 bprm->unsafe |= LSM_UNSAFE_PTRACE;
1434 }
1435
1436 /*
1437 * This isn't strictly necessary, but it makes it harder for LSMs to
1438 * mess up.
1439 */
1440 if (task_no_new_privs(current))
1441 bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1442
1443 t = p;
1444 n_fs = 1;
1445 spin_lock(&p->fs->lock);
1446 rcu_read_lock();
1447 while_each_thread(p, t) {
1448 if (t->fs == p->fs)
1449 n_fs++;
1450 }
1451 rcu_read_unlock();
1452
1453 if (p->fs->users > n_fs)
1454 bprm->unsafe |= LSM_UNSAFE_SHARE;
1455 else
1456 p->fs->in_exec = 1;
1457 spin_unlock(&p->fs->lock);
1458}
1459
1460static void bprm_fill_uid(struct linux_binprm *bprm)
1461{
1462 struct inode *inode;
1463 unsigned int mode;
1464 kuid_t uid;
1465 kgid_t gid;
1466
1467 /*
1468 * Since this can be called multiple times (via prepare_binprm),
1469 * we must clear any previous work done when setting set[ug]id
1470 * bits from any earlier bprm->file uses (for example when run
1471 * first for a setuid script then again for its interpreter).
1472 */
1473 bprm->cred->euid = current_euid();
1474 bprm->cred->egid = current_egid();
1475
1476 if (!mnt_may_suid(bprm->file->f_path.mnt))
1477 return;
1478
1479 if (task_no_new_privs(current))
1480 return;
1481
1482 inode = file_inode(bprm->file);
1483 mode = READ_ONCE(inode->i_mode);
1484 if (!(mode & (S_ISUID|S_ISGID)))
1485 return;
1486
1487 /* Be careful if suid/sgid is set */
1488 inode_lock(inode);
1489
1490 /* reload atomically mode/uid/gid now that lock held */
1491 mode = inode->i_mode;
1492 uid = inode->i_uid;
1493 gid = inode->i_gid;
1494 inode_unlock(inode);
1495
1496 /* We ignore suid/sgid if there are no mappings for them in the ns */
1497 if (!kuid_has_mapping(bprm->cred->user_ns, uid) ||
1498 !kgid_has_mapping(bprm->cred->user_ns, gid))
1499 return;
1500
1501 if (mode & S_ISUID) {
1502 bprm->per_clear |= PER_CLEAR_ON_SETID;
1503 bprm->cred->euid = uid;
1504 }
1505
1506 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1507 bprm->per_clear |= PER_CLEAR_ON_SETID;
1508 bprm->cred->egid = gid;
1509 }
1510}
1511
1512/*
1513 * Fill the binprm structure from the inode.
1514 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1515 *
1516 * This may be called multiple times for binary chains (scripts for example).
1517 */
1518int prepare_binprm(struct linux_binprm *bprm)
1519{
1520 int retval;
1521
1522 bprm_fill_uid(bprm);
1523
1524 /* fill in binprm security blob */
1525 retval = security_bprm_set_creds(bprm);
1526 if (retval)
1527 return retval;
1528 bprm->cred_prepared = 1;
1529
1530 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1531 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1532}
1533
1534EXPORT_SYMBOL(prepare_binprm);
1535
1536/*
1537 * Arguments are '\0' separated strings found at the location bprm->p
1538 * points to; chop off the first by relocating brpm->p to right after
1539 * the first '\0' encountered.
1540 */
1541int remove_arg_zero(struct linux_binprm *bprm)
1542{
1543 int ret = 0;
1544 unsigned long offset;
1545 char *kaddr;
1546 struct page *page;
1547
1548 if (!bprm->argc)
1549 return 0;
1550
1551 do {
1552 offset = bprm->p & ~PAGE_MASK;
1553 page = get_arg_page(bprm, bprm->p, 0);
1554 if (!page) {
1555 ret = -EFAULT;
1556 goto out;
1557 }
1558 kaddr = kmap_atomic(page);
1559
1560 for (; offset < PAGE_SIZE && kaddr[offset];
1561 offset++, bprm->p++)
1562 ;
1563
1564 kunmap_atomic(kaddr);
1565 put_arg_page(page);
1566 } while (offset == PAGE_SIZE);
1567
1568 bprm->p++;
1569 bprm->argc--;
1570 ret = 0;
1571
1572out:
1573 return ret;
1574}
1575EXPORT_SYMBOL(remove_arg_zero);
1576
1577#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1578/*
1579 * cycle the list of binary formats handler, until one recognizes the image
1580 */
1581int search_binary_handler(struct linux_binprm *bprm)
1582{
1583 bool need_retry = IS_ENABLED(CONFIG_MODULES);
1584 struct linux_binfmt *fmt;
1585 int retval;
1586
1587 /* This allows 4 levels of binfmt rewrites before failing hard. */
1588 if (bprm->recursion_depth > 5)
1589 return -ELOOP;
1590
1591 retval = security_bprm_check(bprm);
1592 if (retval)
1593 return retval;
1594
1595 retval = -ENOENT;
1596 retry:
1597 read_lock(&binfmt_lock);
1598 list_for_each_entry(fmt, &formats, lh) {
1599 if (!try_module_get(fmt->module))
1600 continue;
1601 read_unlock(&binfmt_lock);
1602 bprm->recursion_depth++;
1603 retval = fmt->load_binary(bprm);
1604 read_lock(&binfmt_lock);
1605 put_binfmt(fmt);
1606 bprm->recursion_depth--;
1607 if (retval < 0 && !bprm->mm) {
1608 /* we got to flush_old_exec() and failed after it */
1609 read_unlock(&binfmt_lock);
1610 force_sigsegv(SIGSEGV, current);
1611 return retval;
1612 }
1613 if (retval != -ENOEXEC || !bprm->file) {
1614 read_unlock(&binfmt_lock);
1615 return retval;
1616 }
1617 }
1618 read_unlock(&binfmt_lock);
1619
1620 if (need_retry) {
1621 if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
1622 printable(bprm->buf[2]) && printable(bprm->buf[3]))
1623 return retval;
1624 if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
1625 return retval;
1626 need_retry = false;
1627 goto retry;
1628 }
1629
1630 return retval;
1631}
1632EXPORT_SYMBOL(search_binary_handler);
1633
1634static int exec_binprm(struct linux_binprm *bprm)
1635{
1636 pid_t old_pid, old_vpid;
1637 int ret;
1638
1639 /* Need to fetch pid before load_binary changes it */
1640 old_pid = current->pid;
1641 rcu_read_lock();
1642 old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1643 rcu_read_unlock();
1644
1645 ret = search_binary_handler(bprm);
1646 if (ret >= 0) {
1647 audit_bprm(bprm);
1648 trace_sched_process_exec(current, old_pid, bprm);
1649 ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1650 proc_exec_connector(current);
1651 }
1652
1653 return ret;
1654}
1655
1656/*
1657 * sys_execve() executes a new program.
1658 */
1659static int do_execveat_common(int fd, struct filename *filename,
1660 struct user_arg_ptr argv,
1661 struct user_arg_ptr envp,
1662 int flags)
1663{
1664 char *pathbuf = NULL;
1665 struct linux_binprm *bprm;
1666 struct file *file;
1667 struct files_struct *displaced;
1668 int retval;
1669
1670 if (IS_ERR(filename))
1671 return PTR_ERR(filename);
1672
1673 /*
1674 * We move the actual failure in case of RLIMIT_NPROC excess from
1675 * set*uid() to execve() because too many poorly written programs
1676 * don't check setuid() return code. Here we additionally recheck
1677 * whether NPROC limit is still exceeded.
1678 */
1679 if ((current->flags & PF_NPROC_EXCEEDED) &&
1680 atomic_read(&current_user()->processes) > rlimit(RLIMIT_NPROC)) {
1681 retval = -EAGAIN;
1682 goto out_ret;
1683 }
1684
1685 /* We're below the limit (still or again), so we don't want to make
1686 * further execve() calls fail. */
1687 current->flags &= ~PF_NPROC_EXCEEDED;
1688
1689 retval = unshare_files(&displaced);
1690 if (retval)
1691 goto out_ret;
1692
1693 retval = -ENOMEM;
1694 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1695 if (!bprm)
1696 goto out_files;
1697
1698 retval = prepare_bprm_creds(bprm);
1699 if (retval)
1700 goto out_free;
1701
1702 check_unsafe_exec(bprm);
1703 current->in_execve = 1;
1704
1705 file = do_open_execat(fd, filename, flags);
1706 retval = PTR_ERR(file);
1707 if (IS_ERR(file))
1708 goto out_unmark;
1709
1710 sched_exec();
1711
1712 bprm->file = file;
1713 if (fd == AT_FDCWD || filename->name[0] == '/') {
1714 bprm->filename = filename->name;
1715 } else {
1716 if (filename->name[0] == '\0')
1717 pathbuf = kasprintf(GFP_TEMPORARY, "/dev/fd/%d", fd);
1718 else
1719 pathbuf = kasprintf(GFP_TEMPORARY, "/dev/fd/%d/%s",
1720 fd, filename->name);
1721 if (!pathbuf) {
1722 retval = -ENOMEM;
1723 goto out_unmark;
1724 }
1725 /*
1726 * Record that a name derived from an O_CLOEXEC fd will be
1727 * inaccessible after exec. Relies on having exclusive access to
1728 * current->files (due to unshare_files above).
1729 */
1730 if (close_on_exec(fd, rcu_dereference_raw(current->files->fdt)))
1731 bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;
1732 bprm->filename = pathbuf;
1733 }
1734 bprm->interp = bprm->filename;
1735
1736 retval = bprm_mm_init(bprm);
1737 if (retval)
1738 goto out_unmark;
1739
1740 bprm->argc = count(argv, MAX_ARG_STRINGS);
1741 if ((retval = bprm->argc) < 0)
1742 goto out;
1743
1744 bprm->envc = count(envp, MAX_ARG_STRINGS);
1745 if ((retval = bprm->envc) < 0)
1746 goto out;
1747
1748 retval = prepare_binprm(bprm);
1749 if (retval < 0)
1750 goto out;
1751
1752 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1753 if (retval < 0)
1754 goto out;
1755
1756 bprm->exec = bprm->p;
1757 retval = copy_strings(bprm->envc, envp, bprm);
1758 if (retval < 0)
1759 goto out;
1760
1761 retval = copy_strings(bprm->argc, argv, bprm);
1762 if (retval < 0)
1763 goto out;
1764
1765 would_dump(bprm, bprm->file);
1766
1767 retval = exec_binprm(bprm);
1768 if (retval < 0)
1769 goto out;
1770
1771 /* execve succeeded */
1772 current->fs->in_exec = 0;
1773 current->in_execve = 0;
1774 acct_update_integrals(current);
1775 task_numa_free(current);
1776 free_bprm(bprm);
1777 kfree(pathbuf);
1778 putname(filename);
1779 if (displaced)
1780 put_files_struct(displaced);
1781 return retval;
1782
1783out:
1784 if (bprm->mm) {
1785 acct_arg_size(bprm, 0);
1786 mmput(bprm->mm);
1787 }
1788
1789out_unmark:
1790 current->fs->in_exec = 0;
1791 current->in_execve = 0;
1792
1793out_free:
1794 free_bprm(bprm);
1795 kfree(pathbuf);
1796
1797out_files:
1798 if (displaced)
1799 reset_files_struct(displaced);
1800out_ret:
1801 putname(filename);
1802 return retval;
1803}
1804
1805int do_execve(struct filename *filename,
1806 const char __user *const __user *__argv,
1807 const char __user *const __user *__envp)
1808{
1809 struct user_arg_ptr argv = { .ptr.native = __argv };
1810 struct user_arg_ptr envp = { .ptr.native = __envp };
1811 return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
1812}
1813
1814int do_execveat(int fd, struct filename *filename,
1815 const char __user *const __user *__argv,
1816 const char __user *const __user *__envp,
1817 int flags)
1818{
1819 struct user_arg_ptr argv = { .ptr.native = __argv };
1820 struct user_arg_ptr envp = { .ptr.native = __envp };
1821
1822 return do_execveat_common(fd, filename, argv, envp, flags);
1823}
1824
1825#ifdef CONFIG_COMPAT
1826static int compat_do_execve(struct filename *filename,
1827 const compat_uptr_t __user *__argv,
1828 const compat_uptr_t __user *__envp)
1829{
1830 struct user_arg_ptr argv = {
1831 .is_compat = true,
1832 .ptr.compat = __argv,
1833 };
1834 struct user_arg_ptr envp = {
1835 .is_compat = true,
1836 .ptr.compat = __envp,
1837 };
1838 return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
1839}
1840
1841static int compat_do_execveat(int fd, struct filename *filename,
1842 const compat_uptr_t __user *__argv,
1843 const compat_uptr_t __user *__envp,
1844 int flags)
1845{
1846 struct user_arg_ptr argv = {
1847 .is_compat = true,
1848 .ptr.compat = __argv,
1849 };
1850 struct user_arg_ptr envp = {
1851 .is_compat = true,
1852 .ptr.compat = __envp,
1853 };
1854 return do_execveat_common(fd, filename, argv, envp, flags);
1855}
1856#endif
1857
1858void set_binfmt(struct linux_binfmt *new)
1859{
1860 struct mm_struct *mm = current->mm;
1861
1862 if (mm->binfmt)
1863 module_put(mm->binfmt->module);
1864
1865 mm->binfmt = new;
1866 if (new)
1867 __module_get(new->module);
1868}
1869EXPORT_SYMBOL(set_binfmt);
1870
1871/*
1872 * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
1873 */
1874void set_dumpable(struct mm_struct *mm, int value)
1875{
1876 unsigned long old, new;
1877
1878 if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
1879 return;
1880
1881 do {
1882 old = ACCESS_ONCE(mm->flags);
1883 new = (old & ~MMF_DUMPABLE_MASK) | value;
1884 } while (cmpxchg(&mm->flags, old, new) != old);
1885}
1886
1887SYSCALL_DEFINE3(execve,
1888 const char __user *, filename,
1889 const char __user *const __user *, argv,
1890 const char __user *const __user *, envp)
1891{
1892 return do_execve(getname(filename), argv, envp);
1893}
1894
1895SYSCALL_DEFINE5(execveat,
1896 int, fd, const char __user *, filename,
1897 const char __user *const __user *, argv,
1898 const char __user *const __user *, envp,
1899 int, flags)
1900{
1901 int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
1902
1903 return do_execveat(fd,
1904 getname_flags(filename, lookup_flags, NULL),
1905 argv, envp, flags);
1906}
1907
1908#ifdef CONFIG_COMPAT
1909COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
1910 const compat_uptr_t __user *, argv,
1911 const compat_uptr_t __user *, envp)
1912{
1913 return compat_do_execve(getname(filename), argv, envp);
1914}
1915
1916COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
1917 const char __user *, filename,
1918 const compat_uptr_t __user *, argv,
1919 const compat_uptr_t __user *, envp,
1920 int, flags)
1921{
1922 int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
1923
1924 return compat_do_execveat(fd,
1925 getname_flags(filename, lookup_flags, NULL),
1926 argv, envp, flags);
1927}
1928#endif