1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * linux/fs/exec.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 */
7
8 /*
9 * #!-checking implemented by tytso.
10 */
11 /*
12 * Demand-loading implemented 01.12.91 - no need to read anything but
13 * the header into memory. The inode of the executable is put into
14 * "current->executable", and page faults do the actual loading. Clean.
15 *
16 * Once more I can proudly say that linux stood up to being changed: it
17 * was less than 2 hours work to get demand-loading completely implemented.
18 *
19 * Demand loading changed July 1993 by Eric Youngdale. Use mmap instead,
20 * current->executable is only used by the procfs. This allows a dispatch
21 * table to check for several different types of binary formats. We keep
22 * trying until we recognize the file or we run out of supported binary
23 * formats.
24 */
25
26 #include <linux/kernel_read_file.h>
27 #include <linux/slab.h>
28 #include <linux/file.h>
29 #include <linux/fdtable.h>
30 #include <linux/mm.h>
31 #include <linux/stat.h>
32 #include <linux/fcntl.h>
33 #include <linux/swap.h>
34 #include <linux/string.h>
35 #include <linux/init.h>
36 #include <linux/sched/mm.h>
37 #include <linux/sched/coredump.h>
38 #include <linux/sched/signal.h>
39 #include <linux/sched/numa_balancing.h>
40 #include <linux/sched/task.h>
41 #include <linux/pagemap.h>
42 #include <linux/perf_event.h>
43 #include <linux/highmem.h>
44 #include <linux/spinlock.h>
45 #include <linux/key.h>
46 #include <linux/personality.h>
47 #include <linux/binfmts.h>
48 #include <linux/utsname.h>
49 #include <linux/pid_namespace.h>
50 #include <linux/module.h>
51 #include <linux/namei.h>
52 #include <linux/mount.h>
53 #include <linux/security.h>
54 #include <linux/syscalls.h>
55 #include <linux/tsacct_kern.h>
56 #include <linux/cn_proc.h>
57 #include <linux/audit.h>
58 #include <linux/kmod.h>
59 #include <linux/fsnotify.h>
60 #include <linux/fs_struct.h>
61 #include <linux/oom.h>
62 #include <linux/compat.h>
63 #include <linux/vmalloc.h>
64 #include <linux/io_uring.h>
65 #include <linux/syscall_user_dispatch.h>
66 #include <linux/coredump.h>
67 #include <linux/time_namespace.h>
68 #include <linux/user_events.h>
69
70 #include <linux/uaccess.h>
71 #include <asm/mmu_context.h>
72 #include <asm/tlb.h>
73
74 #include <trace/events/task.h>
75 #include "internal.h"
76
77 #include <trace/events/sched.h>
78
79 static int bprm_creds_from_file(struct linux_binprm *bprm);
80
81 int suid_dumpable = 0;
82
83 static LIST_HEAD(formats);
84 static DEFINE_RWLOCK(binfmt_lock);
85
__register_binfmt(struct linux_binfmt * fmt,int insert)86 void __register_binfmt(struct linux_binfmt * fmt, int insert)
87 {
88 write_lock(&binfmt_lock);
89 insert ? list_add(&fmt->lh, &formats) :
90 list_add_tail(&fmt->lh, &formats);
91 write_unlock(&binfmt_lock);
92 }
93
94 EXPORT_SYMBOL(__register_binfmt);
95
unregister_binfmt(struct linux_binfmt * fmt)96 void unregister_binfmt(struct linux_binfmt * fmt)
97 {
98 write_lock(&binfmt_lock);
99 list_del(&fmt->lh);
100 write_unlock(&binfmt_lock);
101 }
102
103 EXPORT_SYMBOL(unregister_binfmt);
104
put_binfmt(struct linux_binfmt * fmt)105 static inline void put_binfmt(struct linux_binfmt * fmt)
106 {
107 module_put(fmt->module);
108 }
109
path_noexec(const struct path * path)110 bool path_noexec(const struct path *path)
111 {
112 return (path->mnt->mnt_flags & MNT_NOEXEC) ||
113 (path->mnt->mnt_sb->s_iflags & SB_I_NOEXEC);
114 }
115
116 #ifdef CONFIG_USELIB
117 /*
118 * Note that a shared library must be both readable and executable due to
119 * security reasons.
120 *
121 * Also note that we take the address to load from the file itself.
122 */
SYSCALL_DEFINE1(uselib,const char __user *,library)123 SYSCALL_DEFINE1(uselib, const char __user *, library)
124 {
125 struct linux_binfmt *fmt;
126 struct file *file;
127 struct filename *tmp = getname(library);
128 int error = PTR_ERR(tmp);
129 static const struct open_flags uselib_flags = {
130 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
131 .acc_mode = MAY_READ | MAY_EXEC,
132 .intent = LOOKUP_OPEN,
133 .lookup_flags = LOOKUP_FOLLOW,
134 };
135
136 if (IS_ERR(tmp))
137 goto out;
138
139 file = do_filp_open(AT_FDCWD, tmp, &uselib_flags);
140 putname(tmp);
141 error = PTR_ERR(file);
142 if (IS_ERR(file))
143 goto out;
144
145 /*
146 * may_open() has already checked for this, so it should be
147 * impossible to trip now. But we need to be extra cautious
148 * and check again at the very end too.
149 */
150 error = -EACCES;
151 if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
152 path_noexec(&file->f_path)))
153 goto exit;
154
155 error = -ENOEXEC;
156
157 read_lock(&binfmt_lock);
158 list_for_each_entry(fmt, &formats, lh) {
159 if (!fmt->load_shlib)
160 continue;
161 if (!try_module_get(fmt->module))
162 continue;
163 read_unlock(&binfmt_lock);
164 error = fmt->load_shlib(file);
165 read_lock(&binfmt_lock);
166 put_binfmt(fmt);
167 if (error != -ENOEXEC)
168 break;
169 }
170 read_unlock(&binfmt_lock);
171 exit:
172 fput(file);
173 out:
174 return error;
175 }
176 #endif /* #ifdef CONFIG_USELIB */
177
178 #ifdef CONFIG_MMU
179 /*
180 * The nascent bprm->mm is not visible until exec_mmap() but it can
181 * use a lot of memory, account these pages in current->mm temporary
182 * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
183 * change the counter back via acct_arg_size(0).
184 */
acct_arg_size(struct linux_binprm * bprm,unsigned long pages)185 static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
186 {
187 struct mm_struct *mm = current->mm;
188 long diff = (long)(pages - bprm->vma_pages);
189
190 if (!mm || !diff)
191 return;
192
193 bprm->vma_pages = pages;
194 add_mm_counter(mm, MM_ANONPAGES, diff);
195 }
196
get_arg_page(struct linux_binprm * bprm,unsigned long pos,int write)197 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
198 int write)
199 {
200 struct page *page;
201 struct vm_area_struct *vma = bprm->vma;
202 struct mm_struct *mm = bprm->mm;
203 int ret;
204
205 /*
206 * Avoid relying on expanding the stack down in GUP (which
207 * does not work for STACK_GROWSUP anyway), and just do it
208 * by hand ahead of time.
209 */
210 if (write && pos < vma->vm_start) {
211 mmap_write_lock(mm);
212 ret = expand_downwards(vma, pos);
213 if (unlikely(ret < 0)) {
214 mmap_write_unlock(mm);
215 return NULL;
216 }
217 mmap_write_downgrade(mm);
218 } else
219 mmap_read_lock(mm);
220
221 /*
222 * We are doing an exec(). 'current' is the process
223 * doing the exec and 'mm' is the new process's mm.
224 */
225 ret = get_user_pages_remote(mm, pos, 1,
226 write ? FOLL_WRITE : 0,
227 &page, NULL);
228 mmap_read_unlock(mm);
229 if (ret <= 0)
230 return NULL;
231
232 if (write)
233 acct_arg_size(bprm, vma_pages(vma));
234
235 return page;
236 }
237
put_arg_page(struct page * page)238 static void put_arg_page(struct page *page)
239 {
240 put_page(page);
241 }
242
free_arg_pages(struct linux_binprm * bprm)243 static void free_arg_pages(struct linux_binprm *bprm)
244 {
245 }
246
flush_arg_page(struct linux_binprm * bprm,unsigned long pos,struct page * page)247 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
248 struct page *page)
249 {
250 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
251 }
252
__bprm_mm_init(struct linux_binprm * bprm)253 static int __bprm_mm_init(struct linux_binprm *bprm)
254 {
255 int err;
256 struct vm_area_struct *vma = NULL;
257 struct mm_struct *mm = bprm->mm;
258
259 bprm->vma = vma = vm_area_alloc(mm);
260 if (!vma)
261 return -ENOMEM;
262 vma_set_anonymous(vma);
263
264 if (mmap_write_lock_killable(mm)) {
265 err = -EINTR;
266 goto err_free;
267 }
268
269 /*
270 * Place the stack at the largest stack address the architecture
271 * supports. Later, we'll move this to an appropriate place. We don't
272 * use STACK_TOP because that can depend on attributes which aren't
273 * configured yet.
274 */
275 BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
276 vma->vm_end = STACK_TOP_MAX;
277 vma->vm_start = vma->vm_end - PAGE_SIZE;
278 vm_flags_init(vma, VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP);
279 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
280
281 err = insert_vm_struct(mm, vma);
282 if (err)
283 goto err;
284
285 mm->stack_vm = mm->total_vm = 1;
286 mmap_write_unlock(mm);
287 bprm->p = vma->vm_end - sizeof(void *);
288 return 0;
289 err:
290 mmap_write_unlock(mm);
291 err_free:
292 bprm->vma = NULL;
293 vm_area_free(vma);
294 return err;
295 }
296
valid_arg_len(struct linux_binprm * bprm,long len)297 static bool valid_arg_len(struct linux_binprm *bprm, long len)
298 {
299 return len <= MAX_ARG_STRLEN;
300 }
301
302 #else
303
acct_arg_size(struct linux_binprm * bprm,unsigned long pages)304 static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
305 {
306 }
307
get_arg_page(struct linux_binprm * bprm,unsigned long pos,int write)308 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
309 int write)
310 {
311 struct page *page;
312
313 page = bprm->page[pos / PAGE_SIZE];
314 if (!page && write) {
315 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
316 if (!page)
317 return NULL;
318 bprm->page[pos / PAGE_SIZE] = page;
319 }
320
321 return page;
322 }
323
put_arg_page(struct page * page)324 static void put_arg_page(struct page *page)
325 {
326 }
327
free_arg_page(struct linux_binprm * bprm,int i)328 static void free_arg_page(struct linux_binprm *bprm, int i)
329 {
330 if (bprm->page[i]) {
331 __free_page(bprm->page[i]);
332 bprm->page[i] = NULL;
333 }
334 }
335
free_arg_pages(struct linux_binprm * bprm)336 static void free_arg_pages(struct linux_binprm *bprm)
337 {
338 int i;
339
340 for (i = 0; i < MAX_ARG_PAGES; i++)
341 free_arg_page(bprm, i);
342 }
343
flush_arg_page(struct linux_binprm * bprm,unsigned long pos,struct page * page)344 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
345 struct page *page)
346 {
347 }
348
__bprm_mm_init(struct linux_binprm * bprm)349 static int __bprm_mm_init(struct linux_binprm *bprm)
350 {
351 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
352 return 0;
353 }
354
valid_arg_len(struct linux_binprm * bprm,long len)355 static bool valid_arg_len(struct linux_binprm *bprm, long len)
356 {
357 return len <= bprm->p;
358 }
359
360 #endif /* CONFIG_MMU */
361
362 /*
363 * Create a new mm_struct and populate it with a temporary stack
364 * vm_area_struct. We don't have enough context at this point to set the stack
365 * flags, permissions, and offset, so we use temporary values. We'll update
366 * them later in setup_arg_pages().
367 */
bprm_mm_init(struct linux_binprm * bprm)368 static int bprm_mm_init(struct linux_binprm *bprm)
369 {
370 int err;
371 struct mm_struct *mm = NULL;
372
373 bprm->mm = mm = mm_alloc();
374 err = -ENOMEM;
375 if (!mm)
376 goto err;
377
378 /* Save current stack limit for all calculations made during exec. */
379 task_lock(current->group_leader);
380 bprm->rlim_stack = current->signal->rlim[RLIMIT_STACK];
381 task_unlock(current->group_leader);
382
383 err = __bprm_mm_init(bprm);
384 if (err)
385 goto err;
386
387 return 0;
388
389 err:
390 if (mm) {
391 bprm->mm = NULL;
392 mmdrop(mm);
393 }
394
395 return err;
396 }
397
398 struct user_arg_ptr {
399 #ifdef CONFIG_COMPAT
400 bool is_compat;
401 #endif
402 union {
403 const char __user *const __user *native;
404 #ifdef CONFIG_COMPAT
405 const compat_uptr_t __user *compat;
406 #endif
407 } ptr;
408 };
409
get_user_arg_ptr(struct user_arg_ptr argv,int nr)410 static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
411 {
412 const char __user *native;
413
414 #ifdef CONFIG_COMPAT
415 if (unlikely(argv.is_compat)) {
416 compat_uptr_t compat;
417
418 if (get_user(compat, argv.ptr.compat + nr))
419 return ERR_PTR(-EFAULT);
420
421 return compat_ptr(compat);
422 }
423 #endif
424
425 if (get_user(native, argv.ptr.native + nr))
426 return ERR_PTR(-EFAULT);
427
428 return native;
429 }
430
431 /*
432 * count() counts the number of strings in array ARGV.
433 */
count(struct user_arg_ptr argv,int max)434 static int count(struct user_arg_ptr argv, int max)
435 {
436 int i = 0;
437
438 if (argv.ptr.native != NULL) {
439 for (;;) {
440 const char __user *p = get_user_arg_ptr(argv, i);
441
442 if (!p)
443 break;
444
445 if (IS_ERR(p))
446 return -EFAULT;
447
448 if (i >= max)
449 return -E2BIG;
450 ++i;
451
452 if (fatal_signal_pending(current))
453 return -ERESTARTNOHAND;
454 cond_resched();
455 }
456 }
457 return i;
458 }
459
count_strings_kernel(const char * const * argv)460 static int count_strings_kernel(const char *const *argv)
461 {
462 int i;
463
464 if (!argv)
465 return 0;
466
467 for (i = 0; argv[i]; ++i) {
468 if (i >= MAX_ARG_STRINGS)
469 return -E2BIG;
470 if (fatal_signal_pending(current))
471 return -ERESTARTNOHAND;
472 cond_resched();
473 }
474 return i;
475 }
476
bprm_stack_limits(struct linux_binprm * bprm)477 static int bprm_stack_limits(struct linux_binprm *bprm)
478 {
479 unsigned long limit, ptr_size;
480
481 /*
482 * Limit to 1/4 of the max stack size or 3/4 of _STK_LIM
483 * (whichever is smaller) for the argv+env strings.
484 * This ensures that:
485 * - the remaining binfmt code will not run out of stack space,
486 * - the program will have a reasonable amount of stack left
487 * to work from.
488 */
489 limit = _STK_LIM / 4 * 3;
490 limit = min(limit, bprm->rlim_stack.rlim_cur / 4);
491 /*
492 * We've historically supported up to 32 pages (ARG_MAX)
493 * of argument strings even with small stacks
494 */
495 limit = max_t(unsigned long, limit, ARG_MAX);
496 /*
497 * We must account for the size of all the argv and envp pointers to
498 * the argv and envp strings, since they will also take up space in
499 * the stack. They aren't stored until much later when we can't
500 * signal to the parent that the child has run out of stack space.
501 * Instead, calculate it here so it's possible to fail gracefully.
502 *
503 * In the case of argc = 0, make sure there is space for adding a
504 * empty string (which will bump argc to 1), to ensure confused
505 * userspace programs don't start processing from argv[1], thinking
506 * argc can never be 0, to keep them from walking envp by accident.
507 * See do_execveat_common().
508 */
509 ptr_size = (max(bprm->argc, 1) + bprm->envc) * sizeof(void *);
510 if (limit <= ptr_size)
511 return -E2BIG;
512 limit -= ptr_size;
513
514 bprm->argmin = bprm->p - limit;
515 return 0;
516 }
517
518 /*
519 * 'copy_strings()' copies argument/environment strings from the old
520 * processes's memory to the new process's stack. The call to get_user_pages()
521 * ensures the destination page is created and not swapped out.
522 */
copy_strings(int argc,struct user_arg_ptr argv,struct linux_binprm * bprm)523 static int copy_strings(int argc, struct user_arg_ptr argv,
524 struct linux_binprm *bprm)
525 {
526 struct page *kmapped_page = NULL;
527 char *kaddr = NULL;
528 unsigned long kpos = 0;
529 int ret;
530
531 while (argc-- > 0) {
532 const char __user *str;
533 int len;
534 unsigned long pos;
535
536 ret = -EFAULT;
537 str = get_user_arg_ptr(argv, argc);
538 if (IS_ERR(str))
539 goto out;
540
541 len = strnlen_user(str, MAX_ARG_STRLEN);
542 if (!len)
543 goto out;
544
545 ret = -E2BIG;
546 if (!valid_arg_len(bprm, len))
547 goto out;
548
549 /* We're going to work our way backwards. */
550 pos = bprm->p;
551 str += len;
552 bprm->p -= len;
553 #ifdef CONFIG_MMU
554 if (bprm->p < bprm->argmin)
555 goto out;
556 #endif
557
558 while (len > 0) {
559 int offset, bytes_to_copy;
560
561 if (fatal_signal_pending(current)) {
562 ret = -ERESTARTNOHAND;
563 goto out;
564 }
565 cond_resched();
566
567 offset = pos % PAGE_SIZE;
568 if (offset == 0)
569 offset = PAGE_SIZE;
570
571 bytes_to_copy = offset;
572 if (bytes_to_copy > len)
573 bytes_to_copy = len;
574
575 offset -= bytes_to_copy;
576 pos -= bytes_to_copy;
577 str -= bytes_to_copy;
578 len -= bytes_to_copy;
579
580 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
581 struct page *page;
582
583 page = get_arg_page(bprm, pos, 1);
584 if (!page) {
585 ret = -E2BIG;
586 goto out;
587 }
588
589 if (kmapped_page) {
590 flush_dcache_page(kmapped_page);
591 kunmap_local(kaddr);
592 put_arg_page(kmapped_page);
593 }
594 kmapped_page = page;
595 kaddr = kmap_local_page(kmapped_page);
596 kpos = pos & PAGE_MASK;
597 flush_arg_page(bprm, kpos, kmapped_page);
598 }
599 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
600 ret = -EFAULT;
601 goto out;
602 }
603 }
604 }
605 ret = 0;
606 out:
607 if (kmapped_page) {
608 flush_dcache_page(kmapped_page);
609 kunmap_local(kaddr);
610 put_arg_page(kmapped_page);
611 }
612 return ret;
613 }
614
615 /*
616 * Copy and argument/environment string from the kernel to the processes stack.
617 */
copy_string_kernel(const char * arg,struct linux_binprm * bprm)618 int copy_string_kernel(const char *arg, struct linux_binprm *bprm)
619 {
620 int len = strnlen(arg, MAX_ARG_STRLEN) + 1 /* terminating NUL */;
621 unsigned long pos = bprm->p;
622
623 if (len == 0)
624 return -EFAULT;
625 if (!valid_arg_len(bprm, len))
626 return -E2BIG;
627
628 /* We're going to work our way backwards. */
629 arg += len;
630 bprm->p -= len;
631 if (IS_ENABLED(CONFIG_MMU) && bprm->p < bprm->argmin)
632 return -E2BIG;
633
634 while (len > 0) {
635 unsigned int bytes_to_copy = min_t(unsigned int, len,
636 min_not_zero(offset_in_page(pos), PAGE_SIZE));
637 struct page *page;
638
639 pos -= bytes_to_copy;
640 arg -= bytes_to_copy;
641 len -= bytes_to_copy;
642
643 page = get_arg_page(bprm, pos, 1);
644 if (!page)
645 return -E2BIG;
646 flush_arg_page(bprm, pos & PAGE_MASK, page);
647 memcpy_to_page(page, offset_in_page(pos), arg, bytes_to_copy);
648 put_arg_page(page);
649 }
650
651 return 0;
652 }
653 EXPORT_SYMBOL(copy_string_kernel);
654
copy_strings_kernel(int argc,const char * const * argv,struct linux_binprm * bprm)655 static int copy_strings_kernel(int argc, const char *const *argv,
656 struct linux_binprm *bprm)
657 {
658 while (argc-- > 0) {
659 int ret = copy_string_kernel(argv[argc], bprm);
660 if (ret < 0)
661 return ret;
662 if (fatal_signal_pending(current))
663 return -ERESTARTNOHAND;
664 cond_resched();
665 }
666 return 0;
667 }
668
669 #ifdef CONFIG_MMU
670
671 /*
672 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
673 * the binfmt code determines where the new stack should reside, we shift it to
674 * its final location. The process proceeds as follows:
675 *
676 * 1) Use shift to calculate the new vma endpoints.
677 * 2) Extend vma to cover both the old and new ranges. This ensures the
678 * arguments passed to subsequent functions are consistent.
679 * 3) Move vma's page tables to the new range.
680 * 4) Free up any cleared pgd range.
681 * 5) Shrink the vma to cover only the new range.
682 */
shift_arg_pages(struct vm_area_struct * vma,unsigned long shift)683 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
684 {
685 struct mm_struct *mm = vma->vm_mm;
686 unsigned long old_start = vma->vm_start;
687 unsigned long old_end = vma->vm_end;
688 unsigned long length = old_end - old_start;
689 unsigned long new_start = old_start - shift;
690 unsigned long new_end = old_end - shift;
691 VMA_ITERATOR(vmi, mm, new_start);
692 struct vm_area_struct *next;
693 struct mmu_gather tlb;
694
695 BUG_ON(new_start > new_end);
696
697 /*
698 * ensure there are no vmas between where we want to go
699 * and where we are
700 */
701 if (vma != vma_next(&vmi))
702 return -EFAULT;
703
704 vma_iter_prev_range(&vmi);
705 /*
706 * cover the whole range: [new_start, old_end)
707 */
708 if (vma_expand(&vmi, vma, new_start, old_end, vma->vm_pgoff, NULL))
709 return -ENOMEM;
710
711 /*
712 * move the page tables downwards, on failure we rely on
713 * process cleanup to remove whatever mess we made.
714 */
715 if (length != move_page_tables(vma, old_start,
716 vma, new_start, length, false))
717 return -ENOMEM;
718
719 lru_add_drain();
720 tlb_gather_mmu(&tlb, mm);
721 next = vma_next(&vmi);
722 if (new_end > old_start) {
723 /*
724 * when the old and new regions overlap clear from new_end.
725 */
726 free_pgd_range(&tlb, new_end, old_end, new_end,
727 next ? next->vm_start : USER_PGTABLES_CEILING);
728 } else {
729 /*
730 * otherwise, clean from old_start; this is done to not touch
731 * the address space in [new_end, old_start) some architectures
732 * have constraints on va-space that make this illegal (IA64) -
733 * for the others its just a little faster.
734 */
735 free_pgd_range(&tlb, old_start, old_end, new_end,
736 next ? next->vm_start : USER_PGTABLES_CEILING);
737 }
738 tlb_finish_mmu(&tlb);
739
740 vma_prev(&vmi);
741 /* Shrink the vma to just the new range */
742 return vma_shrink(&vmi, vma, new_start, new_end, vma->vm_pgoff);
743 }
744
745 /*
746 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
747 * the stack is optionally relocated, and some extra space is added.
748 */
setup_arg_pages(struct linux_binprm * bprm,unsigned long stack_top,int executable_stack)749 int setup_arg_pages(struct linux_binprm *bprm,
750 unsigned long stack_top,
751 int executable_stack)
752 {
753 unsigned long ret;
754 unsigned long stack_shift;
755 struct mm_struct *mm = current->mm;
756 struct vm_area_struct *vma = bprm->vma;
757 struct vm_area_struct *prev = NULL;
758 unsigned long vm_flags;
759 unsigned long stack_base;
760 unsigned long stack_size;
761 unsigned long stack_expand;
762 unsigned long rlim_stack;
763 struct mmu_gather tlb;
764 struct vma_iterator vmi;
765
766 #ifdef CONFIG_STACK_GROWSUP
767 /* Limit stack size */
768 stack_base = bprm->rlim_stack.rlim_max;
769
770 stack_base = calc_max_stack_size(stack_base);
771
772 /* Add space for stack randomization. */
773 stack_base += (STACK_RND_MASK << PAGE_SHIFT);
774
775 /* Make sure we didn't let the argument array grow too large. */
776 if (vma->vm_end - vma->vm_start > stack_base)
777 return -ENOMEM;
778
779 stack_base = PAGE_ALIGN(stack_top - stack_base);
780
781 stack_shift = vma->vm_start - stack_base;
782 mm->arg_start = bprm->p - stack_shift;
783 bprm->p = vma->vm_end - stack_shift;
784 #else
785 stack_top = arch_align_stack(stack_top);
786 stack_top = PAGE_ALIGN(stack_top);
787
788 if (unlikely(stack_top < mmap_min_addr) ||
789 unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
790 return -ENOMEM;
791
792 stack_shift = vma->vm_end - stack_top;
793
794 bprm->p -= stack_shift;
795 mm->arg_start = bprm->p;
796 #endif
797
798 if (bprm->loader)
799 bprm->loader -= stack_shift;
800 bprm->exec -= stack_shift;
801
802 if (mmap_write_lock_killable(mm))
803 return -EINTR;
804
805 vm_flags = VM_STACK_FLAGS;
806
807 /*
808 * Adjust stack execute permissions; explicitly enable for
809 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
810 * (arch default) otherwise.
811 */
812 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
813 vm_flags |= VM_EXEC;
814 else if (executable_stack == EXSTACK_DISABLE_X)
815 vm_flags &= ~VM_EXEC;
816 vm_flags |= mm->def_flags;
817 vm_flags |= VM_STACK_INCOMPLETE_SETUP;
818
819 vma_iter_init(&vmi, mm, vma->vm_start);
820
821 tlb_gather_mmu(&tlb, mm);
822 ret = mprotect_fixup(&vmi, &tlb, vma, &prev, vma->vm_start, vma->vm_end,
823 vm_flags);
824 tlb_finish_mmu(&tlb);
825
826 if (ret)
827 goto out_unlock;
828 BUG_ON(prev != vma);
829
830 if (unlikely(vm_flags & VM_EXEC)) {
831 pr_warn_once("process '%pD4' started with executable stack\n",
832 bprm->file);
833 }
834
835 /* Move stack pages down in memory. */
836 if (stack_shift) {
837 ret = shift_arg_pages(vma, stack_shift);
838 if (ret)
839 goto out_unlock;
840 }
841
842 /* mprotect_fixup is overkill to remove the temporary stack flags */
843 vm_flags_clear(vma, VM_STACK_INCOMPLETE_SETUP);
844
845 stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
846 stack_size = vma->vm_end - vma->vm_start;
847 /*
848 * Align this down to a page boundary as expand_stack
849 * will align it up.
850 */
851 rlim_stack = bprm->rlim_stack.rlim_cur & PAGE_MASK;
852
853 stack_expand = min(rlim_stack, stack_size + stack_expand);
854
855 #ifdef CONFIG_STACK_GROWSUP
856 stack_base = vma->vm_start + stack_expand;
857 #else
858 stack_base = vma->vm_end - stack_expand;
859 #endif
860 current->mm->start_stack = bprm->p;
861 ret = expand_stack_locked(vma, stack_base);
862 if (ret)
863 ret = -EFAULT;
864
865 out_unlock:
866 mmap_write_unlock(mm);
867 return ret;
868 }
869 EXPORT_SYMBOL(setup_arg_pages);
870
871 #else
872
873 /*
874 * Transfer the program arguments and environment from the holding pages
875 * onto the stack. The provided stack pointer is adjusted accordingly.
876 */
transfer_args_to_stack(struct linux_binprm * bprm,unsigned long * sp_location)877 int transfer_args_to_stack(struct linux_binprm *bprm,
878 unsigned long *sp_location)
879 {
880 unsigned long index, stop, sp;
881 int ret = 0;
882
883 stop = bprm->p >> PAGE_SHIFT;
884 sp = *sp_location;
885
886 for (index = MAX_ARG_PAGES - 1; index >= stop; index--) {
887 unsigned int offset = index == stop ? bprm->p & ~PAGE_MASK : 0;
888 char *src = kmap_local_page(bprm->page[index]) + offset;
889 sp -= PAGE_SIZE - offset;
890 if (copy_to_user((void *) sp, src, PAGE_SIZE - offset) != 0)
891 ret = -EFAULT;
892 kunmap_local(src);
893 if (ret)
894 goto out;
895 }
896
897 bprm->exec += *sp_location - MAX_ARG_PAGES * PAGE_SIZE;
898 *sp_location = sp;
899
900 out:
901 return ret;
902 }
903 EXPORT_SYMBOL(transfer_args_to_stack);
904
905 #endif /* CONFIG_MMU */
906
do_open_execat(int fd,struct filename * name,int flags)907 static struct file *do_open_execat(int fd, struct filename *name, int flags)
908 {
909 struct file *file;
910 int err;
911 struct open_flags open_exec_flags = {
912 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
913 .acc_mode = MAY_EXEC,
914 .intent = LOOKUP_OPEN,
915 .lookup_flags = LOOKUP_FOLLOW,
916 };
917
918 if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
919 return ERR_PTR(-EINVAL);
920 if (flags & AT_SYMLINK_NOFOLLOW)
921 open_exec_flags.lookup_flags &= ~LOOKUP_FOLLOW;
922 if (flags & AT_EMPTY_PATH)
923 open_exec_flags.lookup_flags |= LOOKUP_EMPTY;
924
925 file = do_filp_open(fd, name, &open_exec_flags);
926 if (IS_ERR(file))
927 goto out;
928
929 /*
930 * may_open() has already checked for this, so it should be
931 * impossible to trip now. But we need to be extra cautious
932 * and check again at the very end too.
933 */
934 err = -EACCES;
935 if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
936 path_noexec(&file->f_path)))
937 goto exit;
938
939 err = deny_write_access(file);
940 if (err)
941 goto exit;
942
943 out:
944 return file;
945
946 exit:
947 fput(file);
948 return ERR_PTR(err);
949 }
950
open_exec(const char * name)951 struct file *open_exec(const char *name)
952 {
953 struct filename *filename = getname_kernel(name);
954 struct file *f = ERR_CAST(filename);
955
956 if (!IS_ERR(filename)) {
957 f = do_open_execat(AT_FDCWD, filename, 0);
958 putname(filename);
959 }
960 return f;
961 }
962 EXPORT_SYMBOL(open_exec);
963
964 #if defined(CONFIG_BINFMT_FLAT) || defined(CONFIG_BINFMT_ELF_FDPIC)
read_code(struct file * file,unsigned long addr,loff_t pos,size_t len)965 ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
966 {
967 ssize_t res = vfs_read(file, (void __user *)addr, len, &pos);
968 if (res > 0)
969 flush_icache_user_range(addr, addr + len);
970 return res;
971 }
972 EXPORT_SYMBOL(read_code);
973 #endif
974
975 /*
976 * Maps the mm_struct mm into the current task struct.
977 * On success, this function returns with exec_update_lock
978 * held for writing.
979 */
exec_mmap(struct mm_struct * mm)980 static int exec_mmap(struct mm_struct *mm)
981 {
982 struct task_struct *tsk;
983 struct mm_struct *old_mm, *active_mm;
984 int ret;
985
986 /* Notify parent that we're no longer interested in the old VM */
987 tsk = current;
988 old_mm = current->mm;
989 exec_mm_release(tsk, old_mm);
990 if (old_mm)
991 sync_mm_rss(old_mm);
992
993 ret = down_write_killable(&tsk->signal->exec_update_lock);
994 if (ret)
995 return ret;
996
997 if (old_mm) {
998 /*
999 * If there is a pending fatal signal perhaps a signal
1000 * whose default action is to create a coredump get
1001 * out and die instead of going through with the exec.
1002 */
1003 ret = mmap_read_lock_killable(old_mm);
1004 if (ret) {
1005 up_write(&tsk->signal->exec_update_lock);
1006 return ret;
1007 }
1008 }
1009
1010 task_lock(tsk);
1011 membarrier_exec_mmap(mm);
1012
1013 local_irq_disable();
1014 active_mm = tsk->active_mm;
1015 tsk->active_mm = mm;
1016 tsk->mm = mm;
1017 mm_init_cid(mm);
1018 /*
1019 * This prevents preemption while active_mm is being loaded and
1020 * it and mm are being updated, which could cause problems for
1021 * lazy tlb mm refcounting when these are updated by context
1022 * switches. Not all architectures can handle irqs off over
1023 * activate_mm yet.
1024 */
1025 if (!IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
1026 local_irq_enable();
1027 activate_mm(active_mm, mm);
1028 if (IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
1029 local_irq_enable();
1030 lru_gen_add_mm(mm);
1031 task_unlock(tsk);
1032 lru_gen_use_mm(mm);
1033 if (old_mm) {
1034 mmap_read_unlock(old_mm);
1035 BUG_ON(active_mm != old_mm);
1036 setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
1037 mm_update_next_owner(old_mm);
1038 mmput(old_mm);
1039 return 0;
1040 }
1041 mmdrop_lazy_tlb(active_mm);
1042 return 0;
1043 }
1044
de_thread(struct task_struct * tsk)1045 static 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 ((sig->flags & SIGNAL_GROUP_EXIT) || sig->group_exec_task) {
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_exec_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 (__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 cgroup_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_exec_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 cgroup_threadgroup_change_end(tsk);
1103 schedule();
1104 if (__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->start_boottime = leader->start_boottime;
1120
1121 BUG_ON(!same_thread_group(leader, tsk));
1122 /*
1123 * An exec() starts a new thread group with the
1124 * TGID of the previous thread group. Rehash the
1125 * two threads with a switched PID, and release
1126 * the former thread group leader:
1127 */
1128
1129 /* Become a process group leader with the old leader's pid.
1130 * The old leader becomes a thread of the this thread group.
1131 */
1132 exchange_tids(tsk, leader);
1133 transfer_pid(leader, tsk, PIDTYPE_TGID);
1134 transfer_pid(leader, tsk, PIDTYPE_PGID);
1135 transfer_pid(leader, tsk, PIDTYPE_SID);
1136
1137 list_replace_rcu(&leader->tasks, &tsk->tasks);
1138 list_replace_init(&leader->sibling, &tsk->sibling);
1139
1140 tsk->group_leader = tsk;
1141 leader->group_leader = tsk;
1142
1143 tsk->exit_signal = SIGCHLD;
1144 leader->exit_signal = -1;
1145
1146 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
1147 leader->exit_state = EXIT_DEAD;
1148
1149 /*
1150 * We are going to release_task()->ptrace_unlink() silently,
1151 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
1152 * the tracer won't block again waiting for this thread.
1153 */
1154 if (unlikely(leader->ptrace))
1155 __wake_up_parent(leader, leader->parent);
1156 write_unlock_irq(&tasklist_lock);
1157 cgroup_threadgroup_change_end(tsk);
1158
1159 release_task(leader);
1160 }
1161
1162 sig->group_exec_task = NULL;
1163 sig->notify_count = 0;
1164
1165 no_thread_group:
1166 /* we have changed execution domain */
1167 tsk->exit_signal = SIGCHLD;
1168
1169 BUG_ON(!thread_group_leader(tsk));
1170 return 0;
1171
1172 killed:
1173 /* protects against exit_notify() and __exit_signal() */
1174 read_lock(&tasklist_lock);
1175 sig->group_exec_task = NULL;
1176 sig->notify_count = 0;
1177 read_unlock(&tasklist_lock);
1178 return -EAGAIN;
1179 }
1180
1181
1182 /*
1183 * This function makes sure the current process has its own signal table,
1184 * so that flush_signal_handlers can later reset the handlers without
1185 * disturbing other processes. (Other processes might share the signal
1186 * table via the CLONE_SIGHAND option to clone().)
1187 */
unshare_sighand(struct task_struct * me)1188 static int unshare_sighand(struct task_struct *me)
1189 {
1190 struct sighand_struct *oldsighand = me->sighand;
1191
1192 if (refcount_read(&oldsighand->count) != 1) {
1193 struct sighand_struct *newsighand;
1194 /*
1195 * This ->sighand is shared with the CLONE_SIGHAND
1196 * but not CLONE_THREAD task, switch to the new one.
1197 */
1198 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1199 if (!newsighand)
1200 return -ENOMEM;
1201
1202 refcount_set(&newsighand->count, 1);
1203
1204 write_lock_irq(&tasklist_lock);
1205 spin_lock(&oldsighand->siglock);
1206 memcpy(newsighand->action, oldsighand->action,
1207 sizeof(newsighand->action));
1208 rcu_assign_pointer(me->sighand, newsighand);
1209 spin_unlock(&oldsighand->siglock);
1210 write_unlock_irq(&tasklist_lock);
1211
1212 __cleanup_sighand(oldsighand);
1213 }
1214 return 0;
1215 }
1216
__get_task_comm(char * buf,size_t buf_size,struct task_struct * tsk)1217 char *__get_task_comm(char *buf, size_t buf_size, struct task_struct *tsk)
1218 {
1219 task_lock(tsk);
1220 /* Always NUL terminated and zero-padded */
1221 strscpy_pad(buf, tsk->comm, buf_size);
1222 task_unlock(tsk);
1223 return buf;
1224 }
1225 EXPORT_SYMBOL_GPL(__get_task_comm);
1226
1227 /*
1228 * These functions flushes out all traces of the currently running executable
1229 * so that a new one can be started
1230 */
1231
__set_task_comm(struct task_struct * tsk,const char * buf,bool exec)1232 void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
1233 {
1234 task_lock(tsk);
1235 trace_task_rename(tsk, buf);
1236 strscpy_pad(tsk->comm, buf, sizeof(tsk->comm));
1237 task_unlock(tsk);
1238 perf_event_comm(tsk, exec);
1239 }
1240
1241 /*
1242 * Calling this is the point of no return. None of the failures will be
1243 * seen by userspace since either the process is already taking a fatal
1244 * signal (via de_thread() or coredump), or will have SEGV raised
1245 * (after exec_mmap()) by search_binary_handler (see below).
1246 */
begin_new_exec(struct linux_binprm * bprm)1247 int begin_new_exec(struct linux_binprm * bprm)
1248 {
1249 struct task_struct *me = current;
1250 int retval;
1251
1252 /* Once we are committed compute the creds */
1253 retval = bprm_creds_from_file(bprm);
1254 if (retval)
1255 return retval;
1256
1257 /*
1258 * Ensure all future errors are fatal.
1259 */
1260 bprm->point_of_no_return = true;
1261
1262 /*
1263 * Make this the only thread in the thread group.
1264 */
1265 retval = de_thread(me);
1266 if (retval)
1267 goto out;
1268
1269 /*
1270 * Cancel any io_uring activity across execve
1271 */
1272 io_uring_task_cancel();
1273
1274 /* Ensure the files table is not shared. */
1275 retval = unshare_files();
1276 if (retval)
1277 goto out;
1278
1279 /*
1280 * Must be called _before_ exec_mmap() as bprm->mm is
1281 * not visible until then. Doing it here also ensures
1282 * we don't race against replace_mm_exe_file().
1283 */
1284 retval = set_mm_exe_file(bprm->mm, bprm->file);
1285 if (retval)
1286 goto out;
1287
1288 /* If the binary is not readable then enforce mm->dumpable=0 */
1289 would_dump(bprm, bprm->file);
1290 if (bprm->have_execfd)
1291 would_dump(bprm, bprm->executable);
1292
1293 /*
1294 * Release all of the old mmap stuff
1295 */
1296 acct_arg_size(bprm, 0);
1297 retval = exec_mmap(bprm->mm);
1298 if (retval)
1299 goto out;
1300
1301 bprm->mm = NULL;
1302
1303 retval = exec_task_namespaces();
1304 if (retval)
1305 goto out_unlock;
1306
1307 #ifdef CONFIG_POSIX_TIMERS
1308 spin_lock_irq(&me->sighand->siglock);
1309 posix_cpu_timers_exit(me);
1310 spin_unlock_irq(&me->sighand->siglock);
1311 exit_itimers(me);
1312 flush_itimer_signals();
1313 #endif
1314
1315 /*
1316 * Make the signal table private.
1317 */
1318 retval = unshare_sighand(me);
1319 if (retval)
1320 goto out_unlock;
1321
1322 me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC |
1323 PF_NOFREEZE | PF_NO_SETAFFINITY);
1324 flush_thread();
1325 me->personality &= ~bprm->per_clear;
1326
1327 clear_syscall_work_syscall_user_dispatch(me);
1328
1329 /*
1330 * We have to apply CLOEXEC before we change whether the process is
1331 * dumpable (in setup_new_exec) to avoid a race with a process in userspace
1332 * trying to access the should-be-closed file descriptors of a process
1333 * undergoing exec(2).
1334 */
1335 do_close_on_exec(me->files);
1336
1337 if (bprm->secureexec) {
1338 /* Make sure parent cannot signal privileged process. */
1339 me->pdeath_signal = 0;
1340
1341 /*
1342 * For secureexec, reset the stack limit to sane default to
1343 * avoid bad behavior from the prior rlimits. This has to
1344 * happen before arch_pick_mmap_layout(), which examines
1345 * RLIMIT_STACK, but after the point of no return to avoid
1346 * needing to clean up the change on failure.
1347 */
1348 if (bprm->rlim_stack.rlim_cur > _STK_LIM)
1349 bprm->rlim_stack.rlim_cur = _STK_LIM;
1350 }
1351
1352 me->sas_ss_sp = me->sas_ss_size = 0;
1353
1354 /*
1355 * Figure out dumpability. Note that this checking only of current
1356 * is wrong, but userspace depends on it. This should be testing
1357 * bprm->secureexec instead.
1358 */
1359 if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP ||
1360 !(uid_eq(current_euid(), current_uid()) &&
1361 gid_eq(current_egid(), current_gid())))
1362 set_dumpable(current->mm, suid_dumpable);
1363 else
1364 set_dumpable(current->mm, SUID_DUMP_USER);
1365
1366 perf_event_exec();
1367 __set_task_comm(me, kbasename(bprm->filename), true);
1368
1369 /* An exec changes our domain. We are no longer part of the thread
1370 group */
1371 WRITE_ONCE(me->self_exec_id, me->self_exec_id + 1);
1372 flush_signal_handlers(me, 0);
1373
1374 retval = set_cred_ucounts(bprm->cred);
1375 if (retval < 0)
1376 goto out_unlock;
1377
1378 /*
1379 * install the new credentials for this executable
1380 */
1381 security_bprm_committing_creds(bprm);
1382
1383 commit_creds(bprm->cred);
1384 bprm->cred = NULL;
1385
1386 /*
1387 * Disable monitoring for regular users
1388 * when executing setuid binaries. Must
1389 * wait until new credentials are committed
1390 * by commit_creds() above
1391 */
1392 if (get_dumpable(me->mm) != SUID_DUMP_USER)
1393 perf_event_exit_task(me);
1394 /*
1395 * cred_guard_mutex must be held at least to this point to prevent
1396 * ptrace_attach() from altering our determination of the task's
1397 * credentials; any time after this it may be unlocked.
1398 */
1399 security_bprm_committed_creds(bprm);
1400
1401 /* Pass the opened binary to the interpreter. */
1402 if (bprm->have_execfd) {
1403 retval = get_unused_fd_flags(0);
1404 if (retval < 0)
1405 goto out_unlock;
1406 fd_install(retval, bprm->executable);
1407 bprm->executable = NULL;
1408 bprm->execfd = retval;
1409 }
1410 return 0;
1411
1412 out_unlock:
1413 up_write(&me->signal->exec_update_lock);
1414 if (!bprm->cred)
1415 mutex_unlock(&me->signal->cred_guard_mutex);
1416
1417 out:
1418 return retval;
1419 }
1420 EXPORT_SYMBOL(begin_new_exec);
1421
would_dump(struct linux_binprm * bprm,struct file * file)1422 void would_dump(struct linux_binprm *bprm, struct file *file)
1423 {
1424 struct inode *inode = file_inode(file);
1425 struct mnt_idmap *idmap = file_mnt_idmap(file);
1426 if (inode_permission(idmap, inode, MAY_READ) < 0) {
1427 struct user_namespace *old, *user_ns;
1428 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1429
1430 /* Ensure mm->user_ns contains the executable */
1431 user_ns = old = bprm->mm->user_ns;
1432 while ((user_ns != &init_user_ns) &&
1433 !privileged_wrt_inode_uidgid(user_ns, idmap, inode))
1434 user_ns = user_ns->parent;
1435
1436 if (old != user_ns) {
1437 bprm->mm->user_ns = get_user_ns(user_ns);
1438 put_user_ns(old);
1439 }
1440 }
1441 }
1442 EXPORT_SYMBOL(would_dump);
1443
setup_new_exec(struct linux_binprm * bprm)1444 void setup_new_exec(struct linux_binprm * bprm)
1445 {
1446 /* Setup things that can depend upon the personality */
1447 struct task_struct *me = current;
1448
1449 arch_pick_mmap_layout(me->mm, &bprm->rlim_stack);
1450
1451 arch_setup_new_exec();
1452
1453 /* Set the new mm task size. We have to do that late because it may
1454 * depend on TIF_32BIT which is only updated in flush_thread() on
1455 * some architectures like powerpc
1456 */
1457 me->mm->task_size = TASK_SIZE;
1458 up_write(&me->signal->exec_update_lock);
1459 mutex_unlock(&me->signal->cred_guard_mutex);
1460 }
1461 EXPORT_SYMBOL(setup_new_exec);
1462
1463 /* Runs immediately before start_thread() takes over. */
finalize_exec(struct linux_binprm * bprm)1464 void finalize_exec(struct linux_binprm *bprm)
1465 {
1466 /* Store any stack rlimit changes before starting thread. */
1467 task_lock(current->group_leader);
1468 current->signal->rlim[RLIMIT_STACK] = bprm->rlim_stack;
1469 task_unlock(current->group_leader);
1470 }
1471 EXPORT_SYMBOL(finalize_exec);
1472
1473 /*
1474 * Prepare credentials and lock ->cred_guard_mutex.
1475 * setup_new_exec() commits the new creds and drops the lock.
1476 * Or, if exec fails before, free_bprm() should release ->cred
1477 * and unlock.
1478 */
prepare_bprm_creds(struct linux_binprm * bprm)1479 static int prepare_bprm_creds(struct linux_binprm *bprm)
1480 {
1481 if (mutex_lock_interruptible(¤t->signal->cred_guard_mutex))
1482 return -ERESTARTNOINTR;
1483
1484 bprm->cred = prepare_exec_creds();
1485 if (likely(bprm->cred))
1486 return 0;
1487
1488 mutex_unlock(¤t->signal->cred_guard_mutex);
1489 return -ENOMEM;
1490 }
1491
free_bprm(struct linux_binprm * bprm)1492 static void free_bprm(struct linux_binprm *bprm)
1493 {
1494 if (bprm->mm) {
1495 acct_arg_size(bprm, 0);
1496 mmput(bprm->mm);
1497 }
1498 free_arg_pages(bprm);
1499 if (bprm->cred) {
1500 mutex_unlock(¤t->signal->cred_guard_mutex);
1501 abort_creds(bprm->cred);
1502 }
1503 if (bprm->file) {
1504 allow_write_access(bprm->file);
1505 fput(bprm->file);
1506 }
1507 if (bprm->executable)
1508 fput(bprm->executable);
1509 /* If a binfmt changed the interp, free it. */
1510 if (bprm->interp != bprm->filename)
1511 kfree(bprm->interp);
1512 kfree(bprm->fdpath);
1513 kfree(bprm);
1514 }
1515
alloc_bprm(int fd,struct filename * filename)1516 static struct linux_binprm *alloc_bprm(int fd, struct filename *filename)
1517 {
1518 struct linux_binprm *bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1519 int retval = -ENOMEM;
1520 if (!bprm)
1521 goto out;
1522
1523 if (fd == AT_FDCWD || filename->name[0] == '/') {
1524 bprm->filename = filename->name;
1525 } else {
1526 if (filename->name[0] == '\0')
1527 bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d", fd);
1528 else
1529 bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d/%s",
1530 fd, filename->name);
1531 if (!bprm->fdpath)
1532 goto out_free;
1533
1534 bprm->filename = bprm->fdpath;
1535 }
1536 bprm->interp = bprm->filename;
1537
1538 retval = bprm_mm_init(bprm);
1539 if (retval)
1540 goto out_free;
1541 return bprm;
1542
1543 out_free:
1544 free_bprm(bprm);
1545 out:
1546 return ERR_PTR(retval);
1547 }
1548
bprm_change_interp(const char * interp,struct linux_binprm * bprm)1549 int bprm_change_interp(const char *interp, struct linux_binprm *bprm)
1550 {
1551 /* If a binfmt changed the interp, free it first. */
1552 if (bprm->interp != bprm->filename)
1553 kfree(bprm->interp);
1554 bprm->interp = kstrdup(interp, GFP_KERNEL);
1555 if (!bprm->interp)
1556 return -ENOMEM;
1557 return 0;
1558 }
1559 EXPORT_SYMBOL(bprm_change_interp);
1560
1561 /*
1562 * determine how safe it is to execute the proposed program
1563 * - the caller must hold ->cred_guard_mutex to protect against
1564 * PTRACE_ATTACH or seccomp thread-sync
1565 */
check_unsafe_exec(struct linux_binprm * bprm)1566 static void check_unsafe_exec(struct linux_binprm *bprm)
1567 {
1568 struct task_struct *p = current, *t;
1569 unsigned n_fs;
1570
1571 if (p->ptrace)
1572 bprm->unsafe |= LSM_UNSAFE_PTRACE;
1573
1574 /*
1575 * This isn't strictly necessary, but it makes it harder for LSMs to
1576 * mess up.
1577 */
1578 if (task_no_new_privs(current))
1579 bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1580
1581 /*
1582 * If another task is sharing our fs, we cannot safely
1583 * suid exec because the differently privileged task
1584 * will be able to manipulate the current directory, etc.
1585 * It would be nice to force an unshare instead...
1586 */
1587 t = p;
1588 n_fs = 1;
1589 spin_lock(&p->fs->lock);
1590 rcu_read_lock();
1591 while_each_thread(p, t) {
1592 if (t->fs == p->fs)
1593 n_fs++;
1594 }
1595 rcu_read_unlock();
1596
1597 if (p->fs->users > n_fs)
1598 bprm->unsafe |= LSM_UNSAFE_SHARE;
1599 else
1600 p->fs->in_exec = 1;
1601 spin_unlock(&p->fs->lock);
1602 }
1603
bprm_fill_uid(struct linux_binprm * bprm,struct file * file)1604 static void bprm_fill_uid(struct linux_binprm *bprm, struct file *file)
1605 {
1606 /* Handle suid and sgid on files */
1607 struct mnt_idmap *idmap;
1608 struct inode *inode = file_inode(file);
1609 unsigned int mode;
1610 vfsuid_t vfsuid;
1611 vfsgid_t vfsgid;
1612 int err;
1613
1614 if (!mnt_may_suid(file->f_path.mnt))
1615 return;
1616
1617 if (task_no_new_privs(current))
1618 return;
1619
1620 mode = READ_ONCE(inode->i_mode);
1621 if (!(mode & (S_ISUID|S_ISGID)))
1622 return;
1623
1624 idmap = file_mnt_idmap(file);
1625
1626 /* Be careful if suid/sgid is set */
1627 inode_lock(inode);
1628
1629 /* Atomically reload and check mode/uid/gid now that lock held. */
1630 mode = inode->i_mode;
1631 vfsuid = i_uid_into_vfsuid(idmap, inode);
1632 vfsgid = i_gid_into_vfsgid(idmap, inode);
1633 err = inode_permission(idmap, inode, MAY_EXEC);
1634 inode_unlock(inode);
1635
1636 /* Did the exec bit vanish out from under us? Give up. */
1637 if (err)
1638 return;
1639
1640 /* We ignore suid/sgid if there are no mappings for them in the ns */
1641 if (!vfsuid_has_mapping(bprm->cred->user_ns, vfsuid) ||
1642 !vfsgid_has_mapping(bprm->cred->user_ns, vfsgid))
1643 return;
1644
1645 if (mode & S_ISUID) {
1646 bprm->per_clear |= PER_CLEAR_ON_SETID;
1647 bprm->cred->euid = vfsuid_into_kuid(vfsuid);
1648 }
1649
1650 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1651 bprm->per_clear |= PER_CLEAR_ON_SETID;
1652 bprm->cred->egid = vfsgid_into_kgid(vfsgid);
1653 }
1654 }
1655
1656 /*
1657 * Compute brpm->cred based upon the final binary.
1658 */
bprm_creds_from_file(struct linux_binprm * bprm)1659 static int bprm_creds_from_file(struct linux_binprm *bprm)
1660 {
1661 /* Compute creds based on which file? */
1662 struct file *file = bprm->execfd_creds ? bprm->executable : bprm->file;
1663
1664 bprm_fill_uid(bprm, file);
1665 return security_bprm_creds_from_file(bprm, file);
1666 }
1667
1668 /*
1669 * Fill the binprm structure from the inode.
1670 * Read the first BINPRM_BUF_SIZE bytes
1671 *
1672 * This may be called multiple times for binary chains (scripts for example).
1673 */
prepare_binprm(struct linux_binprm * bprm)1674 static int prepare_binprm(struct linux_binprm *bprm)
1675 {
1676 loff_t pos = 0;
1677
1678 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1679 return kernel_read(bprm->file, bprm->buf, BINPRM_BUF_SIZE, &pos);
1680 }
1681
1682 /*
1683 * Arguments are '\0' separated strings found at the location bprm->p
1684 * points to; chop off the first by relocating brpm->p to right after
1685 * the first '\0' encountered.
1686 */
remove_arg_zero(struct linux_binprm * bprm)1687 int remove_arg_zero(struct linux_binprm *bprm)
1688 {
1689 int ret = 0;
1690 unsigned long offset;
1691 char *kaddr;
1692 struct page *page;
1693
1694 if (!bprm->argc)
1695 return 0;
1696
1697 do {
1698 offset = bprm->p & ~PAGE_MASK;
1699 page = get_arg_page(bprm, bprm->p, 0);
1700 if (!page) {
1701 ret = -EFAULT;
1702 goto out;
1703 }
1704 kaddr = kmap_local_page(page);
1705
1706 for (; offset < PAGE_SIZE && kaddr[offset];
1707 offset++, bprm->p++)
1708 ;
1709
1710 kunmap_local(kaddr);
1711 put_arg_page(page);
1712 } while (offset == PAGE_SIZE);
1713
1714 bprm->p++;
1715 bprm->argc--;
1716 ret = 0;
1717
1718 out:
1719 return ret;
1720 }
1721 EXPORT_SYMBOL(remove_arg_zero);
1722
1723 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1724 /*
1725 * cycle the list of binary formats handler, until one recognizes the image
1726 */
search_binary_handler(struct linux_binprm * bprm)1727 static int search_binary_handler(struct linux_binprm *bprm)
1728 {
1729 bool need_retry = IS_ENABLED(CONFIG_MODULES);
1730 struct linux_binfmt *fmt;
1731 int retval;
1732
1733 retval = prepare_binprm(bprm);
1734 if (retval < 0)
1735 return retval;
1736
1737 retval = security_bprm_check(bprm);
1738 if (retval)
1739 return retval;
1740
1741 retval = -ENOENT;
1742 retry:
1743 read_lock(&binfmt_lock);
1744 list_for_each_entry(fmt, &formats, lh) {
1745 if (!try_module_get(fmt->module))
1746 continue;
1747 read_unlock(&binfmt_lock);
1748
1749 retval = fmt->load_binary(bprm);
1750
1751 read_lock(&binfmt_lock);
1752 put_binfmt(fmt);
1753 if (bprm->point_of_no_return || (retval != -ENOEXEC)) {
1754 read_unlock(&binfmt_lock);
1755 return retval;
1756 }
1757 }
1758 read_unlock(&binfmt_lock);
1759
1760 if (need_retry) {
1761 if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
1762 printable(bprm->buf[2]) && printable(bprm->buf[3]))
1763 return retval;
1764 if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
1765 return retval;
1766 need_retry = false;
1767 goto retry;
1768 }
1769
1770 return retval;
1771 }
1772
1773 /* binfmt handlers will call back into begin_new_exec() on success. */
exec_binprm(struct linux_binprm * bprm)1774 static int exec_binprm(struct linux_binprm *bprm)
1775 {
1776 pid_t old_pid, old_vpid;
1777 int ret, depth;
1778
1779 /* Need to fetch pid before load_binary changes it */
1780 old_pid = current->pid;
1781 rcu_read_lock();
1782 old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1783 rcu_read_unlock();
1784
1785 /* This allows 4 levels of binfmt rewrites before failing hard. */
1786 for (depth = 0;; depth++) {
1787 struct file *exec;
1788 if (depth > 5)
1789 return -ELOOP;
1790
1791 ret = search_binary_handler(bprm);
1792 if (ret < 0)
1793 return ret;
1794 if (!bprm->interpreter)
1795 break;
1796
1797 exec = bprm->file;
1798 bprm->file = bprm->interpreter;
1799 bprm->interpreter = NULL;
1800
1801 allow_write_access(exec);
1802 if (unlikely(bprm->have_execfd)) {
1803 if (bprm->executable) {
1804 fput(exec);
1805 return -ENOEXEC;
1806 }
1807 bprm->executable = exec;
1808 } else
1809 fput(exec);
1810 }
1811
1812 audit_bprm(bprm);
1813 trace_sched_process_exec(current, old_pid, bprm);
1814 ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1815 proc_exec_connector(current);
1816 return 0;
1817 }
1818
1819 /*
1820 * sys_execve() executes a new program.
1821 */
bprm_execve(struct linux_binprm * bprm,int fd,struct filename * filename,int flags)1822 static int bprm_execve(struct linux_binprm *bprm,
1823 int fd, struct filename *filename, int flags)
1824 {
1825 struct file *file;
1826 int retval;
1827
1828 retval = prepare_bprm_creds(bprm);
1829 if (retval)
1830 return retval;
1831
1832 /*
1833 * Check for unsafe execution states before exec_binprm(), which
1834 * will call back into begin_new_exec(), into bprm_creds_from_file(),
1835 * where setuid-ness is evaluated.
1836 */
1837 check_unsafe_exec(bprm);
1838 current->in_execve = 1;
1839 sched_mm_cid_before_execve(current);
1840
1841 file = do_open_execat(fd, filename, flags);
1842 retval = PTR_ERR(file);
1843 if (IS_ERR(file))
1844 goto out_unmark;
1845
1846 sched_exec();
1847
1848 bprm->file = file;
1849 /*
1850 * Record that a name derived from an O_CLOEXEC fd will be
1851 * inaccessible after exec. This allows the code in exec to
1852 * choose to fail when the executable is not mmaped into the
1853 * interpreter and an open file descriptor is not passed to
1854 * the interpreter. This makes for a better user experience
1855 * than having the interpreter start and then immediately fail
1856 * when it finds the executable is inaccessible.
1857 */
1858 if (bprm->fdpath && get_close_on_exec(fd))
1859 bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;
1860
1861 /* Set the unchanging part of bprm->cred */
1862 retval = security_bprm_creds_for_exec(bprm);
1863 if (retval)
1864 goto out;
1865
1866 retval = exec_binprm(bprm);
1867 if (retval < 0)
1868 goto out;
1869
1870 sched_mm_cid_after_execve(current);
1871 /* execve succeeded */
1872 current->fs->in_exec = 0;
1873 current->in_execve = 0;
1874 rseq_execve(current);
1875 user_events_execve(current);
1876 acct_update_integrals(current);
1877 task_numa_free(current, false);
1878 return retval;
1879
1880 out:
1881 /*
1882 * If past the point of no return ensure the code never
1883 * returns to the userspace process. Use an existing fatal
1884 * signal if present otherwise terminate the process with
1885 * SIGSEGV.
1886 */
1887 if (bprm->point_of_no_return && !fatal_signal_pending(current))
1888 force_fatal_sig(SIGSEGV);
1889
1890 out_unmark:
1891 sched_mm_cid_after_execve(current);
1892 current->fs->in_exec = 0;
1893 current->in_execve = 0;
1894
1895 return retval;
1896 }
1897
do_execveat_common(int fd,struct filename * filename,struct user_arg_ptr argv,struct user_arg_ptr envp,int flags)1898 static int do_execveat_common(int fd, struct filename *filename,
1899 struct user_arg_ptr argv,
1900 struct user_arg_ptr envp,
1901 int flags)
1902 {
1903 struct linux_binprm *bprm;
1904 int retval;
1905
1906 if (IS_ERR(filename))
1907 return PTR_ERR(filename);
1908
1909 /*
1910 * We move the actual failure in case of RLIMIT_NPROC excess from
1911 * set*uid() to execve() because too many poorly written programs
1912 * don't check setuid() return code. Here we additionally recheck
1913 * whether NPROC limit is still exceeded.
1914 */
1915 if ((current->flags & PF_NPROC_EXCEEDED) &&
1916 is_rlimit_overlimit(current_ucounts(), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
1917 retval = -EAGAIN;
1918 goto out_ret;
1919 }
1920
1921 /* We're below the limit (still or again), so we don't want to make
1922 * further execve() calls fail. */
1923 current->flags &= ~PF_NPROC_EXCEEDED;
1924
1925 bprm = alloc_bprm(fd, filename);
1926 if (IS_ERR(bprm)) {
1927 retval = PTR_ERR(bprm);
1928 goto out_ret;
1929 }
1930
1931 retval = count(argv, MAX_ARG_STRINGS);
1932 if (retval == 0)
1933 pr_warn_once("process '%s' launched '%s' with NULL argv: empty string added\n",
1934 current->comm, bprm->filename);
1935 if (retval < 0)
1936 goto out_free;
1937 bprm->argc = retval;
1938
1939 retval = count(envp, MAX_ARG_STRINGS);
1940 if (retval < 0)
1941 goto out_free;
1942 bprm->envc = retval;
1943
1944 retval = bprm_stack_limits(bprm);
1945 if (retval < 0)
1946 goto out_free;
1947
1948 retval = copy_string_kernel(bprm->filename, bprm);
1949 if (retval < 0)
1950 goto out_free;
1951 bprm->exec = bprm->p;
1952
1953 retval = copy_strings(bprm->envc, envp, bprm);
1954 if (retval < 0)
1955 goto out_free;
1956
1957 retval = copy_strings(bprm->argc, argv, bprm);
1958 if (retval < 0)
1959 goto out_free;
1960
1961 /*
1962 * When argv is empty, add an empty string ("") as argv[0] to
1963 * ensure confused userspace programs that start processing
1964 * from argv[1] won't end up walking envp. See also
1965 * bprm_stack_limits().
1966 */
1967 if (bprm->argc == 0) {
1968 retval = copy_string_kernel("", bprm);
1969 if (retval < 0)
1970 goto out_free;
1971 bprm->argc = 1;
1972 }
1973
1974 retval = bprm_execve(bprm, fd, filename, flags);
1975 out_free:
1976 free_bprm(bprm);
1977
1978 out_ret:
1979 putname(filename);
1980 return retval;
1981 }
1982
kernel_execve(const char * kernel_filename,const char * const * argv,const char * const * envp)1983 int kernel_execve(const char *kernel_filename,
1984 const char *const *argv, const char *const *envp)
1985 {
1986 struct filename *filename;
1987 struct linux_binprm *bprm;
1988 int fd = AT_FDCWD;
1989 int retval;
1990
1991 /* It is non-sense for kernel threads to call execve */
1992 if (WARN_ON_ONCE(current->flags & PF_KTHREAD))
1993 return -EINVAL;
1994
1995 filename = getname_kernel(kernel_filename);
1996 if (IS_ERR(filename))
1997 return PTR_ERR(filename);
1998
1999 bprm = alloc_bprm(fd, filename);
2000 if (IS_ERR(bprm)) {
2001 retval = PTR_ERR(bprm);
2002 goto out_ret;
2003 }
2004
2005 retval = count_strings_kernel(argv);
2006 if (WARN_ON_ONCE(retval == 0))
2007 retval = -EINVAL;
2008 if (retval < 0)
2009 goto out_free;
2010 bprm->argc = retval;
2011
2012 retval = count_strings_kernel(envp);
2013 if (retval < 0)
2014 goto out_free;
2015 bprm->envc = retval;
2016
2017 retval = bprm_stack_limits(bprm);
2018 if (retval < 0)
2019 goto out_free;
2020
2021 retval = copy_string_kernel(bprm->filename, bprm);
2022 if (retval < 0)
2023 goto out_free;
2024 bprm->exec = bprm->p;
2025
2026 retval = copy_strings_kernel(bprm->envc, envp, bprm);
2027 if (retval < 0)
2028 goto out_free;
2029
2030 retval = copy_strings_kernel(bprm->argc, argv, bprm);
2031 if (retval < 0)
2032 goto out_free;
2033
2034 retval = bprm_execve(bprm, fd, filename, 0);
2035 out_free:
2036 free_bprm(bprm);
2037 out_ret:
2038 putname(filename);
2039 return retval;
2040 }
2041
do_execve(struct filename * filename,const char __user * const __user * __argv,const char __user * const __user * __envp)2042 static int do_execve(struct filename *filename,
2043 const char __user *const __user *__argv,
2044 const char __user *const __user *__envp)
2045 {
2046 struct user_arg_ptr argv = { .ptr.native = __argv };
2047 struct user_arg_ptr envp = { .ptr.native = __envp };
2048 return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
2049 }
2050
do_execveat(int fd,struct filename * filename,const char __user * const __user * __argv,const char __user * const __user * __envp,int flags)2051 static int do_execveat(int fd, struct filename *filename,
2052 const char __user *const __user *__argv,
2053 const char __user *const __user *__envp,
2054 int flags)
2055 {
2056 struct user_arg_ptr argv = { .ptr.native = __argv };
2057 struct user_arg_ptr envp = { .ptr.native = __envp };
2058
2059 return do_execveat_common(fd, filename, argv, envp, flags);
2060 }
2061
2062 #ifdef CONFIG_COMPAT
compat_do_execve(struct filename * filename,const compat_uptr_t __user * __argv,const compat_uptr_t __user * __envp)2063 static int compat_do_execve(struct filename *filename,
2064 const compat_uptr_t __user *__argv,
2065 const compat_uptr_t __user *__envp)
2066 {
2067 struct user_arg_ptr argv = {
2068 .is_compat = true,
2069 .ptr.compat = __argv,
2070 };
2071 struct user_arg_ptr envp = {
2072 .is_compat = true,
2073 .ptr.compat = __envp,
2074 };
2075 return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
2076 }
2077
compat_do_execveat(int fd,struct filename * filename,const compat_uptr_t __user * __argv,const compat_uptr_t __user * __envp,int flags)2078 static int compat_do_execveat(int fd, struct filename *filename,
2079 const compat_uptr_t __user *__argv,
2080 const compat_uptr_t __user *__envp,
2081 int flags)
2082 {
2083 struct user_arg_ptr argv = {
2084 .is_compat = true,
2085 .ptr.compat = __argv,
2086 };
2087 struct user_arg_ptr envp = {
2088 .is_compat = true,
2089 .ptr.compat = __envp,
2090 };
2091 return do_execveat_common(fd, filename, argv, envp, flags);
2092 }
2093 #endif
2094
set_binfmt(struct linux_binfmt * new)2095 void set_binfmt(struct linux_binfmt *new)
2096 {
2097 struct mm_struct *mm = current->mm;
2098
2099 if (mm->binfmt)
2100 module_put(mm->binfmt->module);
2101
2102 mm->binfmt = new;
2103 if (new)
2104 __module_get(new->module);
2105 }
2106 EXPORT_SYMBOL(set_binfmt);
2107
2108 /*
2109 * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
2110 */
set_dumpable(struct mm_struct * mm,int value)2111 void set_dumpable(struct mm_struct *mm, int value)
2112 {
2113 if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
2114 return;
2115
2116 set_mask_bits(&mm->flags, MMF_DUMPABLE_MASK, value);
2117 }
2118
SYSCALL_DEFINE3(execve,const char __user *,filename,const char __user * const __user *,argv,const char __user * const __user *,envp)2119 SYSCALL_DEFINE3(execve,
2120 const char __user *, filename,
2121 const char __user *const __user *, argv,
2122 const char __user *const __user *, envp)
2123 {
2124 return do_execve(getname(filename), argv, envp);
2125 }
2126
SYSCALL_DEFINE5(execveat,int,fd,const char __user *,filename,const char __user * const __user *,argv,const char __user * const __user *,envp,int,flags)2127 SYSCALL_DEFINE5(execveat,
2128 int, fd, const char __user *, filename,
2129 const char __user *const __user *, argv,
2130 const char __user *const __user *, envp,
2131 int, flags)
2132 {
2133 return do_execveat(fd,
2134 getname_uflags(filename, flags),
2135 argv, envp, flags);
2136 }
2137
2138 #ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE3(execve,const char __user *,filename,const compat_uptr_t __user *,argv,const compat_uptr_t __user *,envp)2139 COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
2140 const compat_uptr_t __user *, argv,
2141 const compat_uptr_t __user *, envp)
2142 {
2143 return compat_do_execve(getname(filename), argv, envp);
2144 }
2145
COMPAT_SYSCALL_DEFINE5(execveat,int,fd,const char __user *,filename,const compat_uptr_t __user *,argv,const compat_uptr_t __user *,envp,int,flags)2146 COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
2147 const char __user *, filename,
2148 const compat_uptr_t __user *, argv,
2149 const compat_uptr_t __user *, envp,
2150 int, flags)
2151 {
2152 return compat_do_execveat(fd,
2153 getname_uflags(filename, flags),
2154 argv, envp, flags);
2155 }
2156 #endif
2157
2158 #ifdef CONFIG_SYSCTL
2159
proc_dointvec_minmax_coredump(struct ctl_table * table,int write,void * buffer,size_t * lenp,loff_t * ppos)2160 static int proc_dointvec_minmax_coredump(struct ctl_table *table, int write,
2161 void *buffer, size_t *lenp, loff_t *ppos)
2162 {
2163 int error = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
2164
2165 if (!error)
2166 validate_coredump_safety();
2167 return error;
2168 }
2169
2170 static struct ctl_table fs_exec_sysctls[] = {
2171 {
2172 .procname = "suid_dumpable",
2173 .data = &suid_dumpable,
2174 .maxlen = sizeof(int),
2175 .mode = 0644,
2176 .proc_handler = proc_dointvec_minmax_coredump,
2177 .extra1 = SYSCTL_ZERO,
2178 .extra2 = SYSCTL_TWO,
2179 },
2180 { }
2181 };
2182
init_fs_exec_sysctls(void)2183 static int __init init_fs_exec_sysctls(void)
2184 {
2185 register_sysctl_init("fs", fs_exec_sysctls);
2186 return 0;
2187 }
2188
2189 fs_initcall(init_fs_exec_sysctls);
2190 #endif /* CONFIG_SYSCTL */
2191