1 // SPDX-License-Identifier: GPL-2.0-only 1
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 ne
13 * the header into memory. The inode of the ex
14 * "current->executable", and page faults do t
15 *
16 * Once more I can proudly say that linux stoo
17 * was less than 2 hours work to get demand-lo
18 *
19 * Demand loading changed July 1993 by Eric Yo
20 * current->executable is only used by the pro
21 * table to check for several different types
22 * trying until we recognize the file or we ru
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 #include <linux/rseq.h>
70 #include <linux/ksm.h>
71
72 #include <linux/uaccess.h>
73 #include <asm/mmu_context.h>
74 #include <asm/tlb.h>
75
76 #include <trace/events/task.h>
77 #include "internal.h"
78
79 #include <trace/events/sched.h>
80
81 static int bprm_creds_from_file(struct linux_b
82
83 int suid_dumpable = 0;
84
85 static LIST_HEAD(formats);
86 static DEFINE_RWLOCK(binfmt_lock);
87
88 void __register_binfmt(struct linux_binfmt * f
89 {
90 write_lock(&binfmt_lock);
91 insert ? list_add(&fmt->lh, &formats)
92 list_add_tail(&fmt->lh, &form
93 write_unlock(&binfmt_lock);
94 }
95
96 EXPORT_SYMBOL(__register_binfmt);
97
98 void unregister_binfmt(struct linux_binfmt * f
99 {
100 write_lock(&binfmt_lock);
101 list_del(&fmt->lh);
102 write_unlock(&binfmt_lock);
103 }
104
105 EXPORT_SYMBOL(unregister_binfmt);
106
107 static inline void put_binfmt(struct linux_bin
108 {
109 module_put(fmt->module);
110 }
111
112 bool path_noexec(const struct path *path)
113 {
114 return (path->mnt->mnt_flags & MNT_NOE
115 (path->mnt->mnt_sb->s_iflags &
116 }
117
118 #ifdef CONFIG_USELIB
119 /*
120 * Note that a shared library must be both rea
121 * security reasons.
122 *
123 * Also note that we take the address to load
124 */
125 SYSCALL_DEFINE1(uselib, const char __user *, l
126 {
127 struct linux_binfmt *fmt;
128 struct file *file;
129 struct filename *tmp = getname(library
130 int error = PTR_ERR(tmp);
131 static const struct open_flags uselib_
132 .open_flag = O_LARGEFILE | O_R
133 .acc_mode = MAY_READ | MAY_EXE
134 .intent = LOOKUP_OPEN,
135 .lookup_flags = LOOKUP_FOLLOW,
136 };
137
138 if (IS_ERR(tmp))
139 goto out;
140
141 file = do_filp_open(AT_FDCWD, tmp, &us
142 putname(tmp);
143 error = PTR_ERR(file);
144 if (IS_ERR(file))
145 goto out;
146
147 /*
148 * Check do_open_execat() for an expla
149 */
150 error = -EACCES;
151 if (WARN_ON_ONCE(!S_ISREG(file_inode(f
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->modul
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 e
181 * use a lot of memory, account these pages in
182 * for oom_badness()->get_mm_rss(). Once exec
183 * change the counter back via acct_arg_size(0
184 */
185 static void acct_arg_size(struct linux_binprm
186 {
187 struct mm_struct *mm = current->mm;
188 long diff = (long)(pages - bprm->vma_p
189
190 if (!mm || !diff)
191 return;
192
193 bprm->vma_pages = pages;
194 add_mm_counter(mm, MM_ANONPAGES, diff)
195 }
196
197 static struct page *get_arg_page(struct linux_
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 stac
207 * does not work for STACK_GROWSUP any
208 * by hand ahead of time.
209 */
210 if (write && pos < vma->vm_start) {
211 mmap_write_lock(mm);
212 ret = expand_downwards(vma, po
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'
223 * doing the exec and 'mm' is the new
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(
234
235 return page;
236 }
237
238 static void put_arg_page(struct page *page)
239 {
240 put_page(page);
241 }
242
243 static void free_arg_pages(struct linux_binprm
244 {
245 }
246
247 static void flush_arg_page(struct linux_binprm
248 struct page *page)
249 {
250 flush_cache_page(bprm->vma, pos, page_
251 }
252
253 static int __bprm_mm_init(struct linux_binprm
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 * Need to be called with mmap write l
271 * held, to avoid race with ksmd.
272 */
273 err = ksm_execve(mm);
274 if (err)
275 goto err_ksm;
276
277 /*
278 * Place the stack at the largest stac
279 * supports. Later, we'll move this to
280 * use STACK_TOP because that can depe
281 * configured yet.
282 */
283 BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK
284 vma->vm_end = STACK_TOP_MAX;
285 vma->vm_start = vma->vm_end - PAGE_SIZ
286 vm_flags_init(vma, VM_SOFTDIRTY | VM_S
287 vma->vm_page_prot = vm_get_page_prot(v
288
289 err = insert_vm_struct(mm, vma);
290 if (err)
291 goto err;
292
293 mm->stack_vm = mm->total_vm = 1;
294 mmap_write_unlock(mm);
295 bprm->p = vma->vm_end - sizeof(void *)
296 return 0;
297 err:
298 ksm_exit(mm);
299 err_ksm:
300 mmap_write_unlock(mm);
301 err_free:
302 bprm->vma = NULL;
303 vm_area_free(vma);
304 return err;
305 }
306
307 static bool valid_arg_len(struct linux_binprm
308 {
309 return len <= MAX_ARG_STRLEN;
310 }
311
312 #else
313
314 static inline void acct_arg_size(struct linux_
315 {
316 }
317
318 static struct page *get_arg_page(struct linux_
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
326 if (!page)
327 return NULL;
328 bprm->page[pos / PAGE_SIZE] =
329 }
330
331 return page;
332 }
333
334 static void put_arg_page(struct page *page)
335 {
336 }
337
338 static void free_arg_page(struct linux_binprm
339 {
340 if (bprm->page[i]) {
341 __free_page(bprm->page[i]);
342 bprm->page[i] = NULL;
343 }
344 }
345
346 static void free_arg_pages(struct linux_binprm
347 {
348 int i;
349
350 for (i = 0; i < MAX_ARG_PAGES; i++)
351 free_arg_page(bprm, i);
352 }
353
354 static void flush_arg_page(struct linux_binprm
355 struct page *page)
356 {
357 }
358
359 static int __bprm_mm_init(struct linux_binprm
360 {
361 bprm->p = PAGE_SIZE * MAX_ARG_PAGES -
362 return 0;
363 }
364
365 static bool valid_arg_len(struct linux_binprm
366 {
367 return len <= bprm->p;
368 }
369
370 #endif /* CONFIG_MMU */
371
372 /*
373 * Create a new mm_struct and populate it with
374 * vm_area_struct. We don't have enough conte
375 * flags, permissions, and offset, so we use t
376 * them later in setup_arg_pages().
377 */
378 static int bprm_mm_init(struct linux_binprm *b
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 /* Save current stack limit for all ca
389 task_lock(current->group_leader);
390 bprm->rlim_stack = current->signal->rl
391 task_unlock(current->group_leader);
392
393 err = __bprm_mm_init(bprm);
394 if (err)
395 goto err;
396
397 return 0;
398
399 err:
400 if (mm) {
401 bprm->mm = NULL;
402 mmdrop(mm);
403 }
404
405 return err;
406 }
407
408 struct user_arg_ptr {
409 #ifdef CONFIG_COMPAT
410 bool is_compat;
411 #endif
412 union {
413 const char __user *const __use
414 #ifdef CONFIG_COMPAT
415 const compat_uptr_t __user *co
416 #endif
417 } ptr;
418 };
419
420 static const char __user *get_user_arg_ptr(str
421 {
422 const char __user *native;
423
424 #ifdef CONFIG_COMPAT
425 if (unlikely(argv.is_compat)) {
426 compat_uptr_t compat;
427
428 if (get_user(compat, argv.ptr.
429 return ERR_PTR(-EFAULT
430
431 return compat_ptr(compat);
432 }
433 #endif
434
435 if (get_user(native, argv.ptr.native +
436 return ERR_PTR(-EFAULT);
437
438 return native;
439 }
440
441 /*
442 * count() counts the number of strings in arr
443 */
444 static int count(struct user_arg_ptr argv, int
445 {
446 int i = 0;
447
448 if (argv.ptr.native != NULL) {
449 for (;;) {
450 const char __user *p =
451
452 if (!p)
453 break;
454
455 if (IS_ERR(p))
456 return -EFAULT
457
458 if (i >= max)
459 return -E2BIG;
460 ++i;
461
462 if (fatal_signal_pendi
463 return -ERESTA
464 cond_resched();
465 }
466 }
467 return i;
468 }
469
470 static int count_strings_kernel(const char *co
471 {
472 int i;
473
474 if (!argv)
475 return 0;
476
477 for (i = 0; argv[i]; ++i) {
478 if (i >= MAX_ARG_STRINGS)
479 return -E2BIG;
480 if (fatal_signal_pending(curre
481 return -ERESTARTNOHAND
482 cond_resched();
483 }
484 return i;
485 }
486
487 static inline int bprm_set_stack_limit(struct
488 unsigne
489 {
490 #ifdef CONFIG_MMU
491 /* Avoid a pathological bprm->p. */
492 if (bprm->p < limit)
493 return -E2BIG;
494 bprm->argmin = bprm->p - limit;
495 #endif
496 return 0;
497 }
498 static inline bool bprm_hit_stack_limit(struct
499 {
500 #ifdef CONFIG_MMU
501 return bprm->p < bprm->argmin;
502 #else
503 return false;
504 #endif
505 }
506
507 /*
508 * Calculate bprm->argmin from:
509 * - _STK_LIM
510 * - ARG_MAX
511 * - bprm->rlim_stack.rlim_cur
512 * - bprm->argc
513 * - bprm->envc
514 * - bprm->p
515 */
516 static int bprm_stack_limits(struct linux_binp
517 {
518 unsigned long limit, ptr_size;
519
520 /*
521 * Limit to 1/4 of the max stack size
522 * (whichever is smaller) for the argv
523 * This ensures that:
524 * - the remaining binfmt code will n
525 * - the program will have a reasonab
526 * to work from.
527 */
528 limit = _STK_LIM / 4 * 3;
529 limit = min(limit, bprm->rlim_stack.rl
530 /*
531 * We've historically supported up to
532 * of argument strings even with small
533 */
534 limit = max_t(unsigned long, limit, AR
535 /* Reject totally pathological counts.
536 if (bprm->argc < 0 || bprm->envc < 0)
537 return -E2BIG;
538 /*
539 * We must account for the size of all
540 * the argv and envp strings, since th
541 * the stack. They aren't stored until
542 * signal to the parent that the child
543 * Instead, calculate it here so it's
544 *
545 * In the case of argc = 0, make sure
546 * empty string (which will bump argc
547 * userspace programs don't start proc
548 * argc can never be 0, to keep them f
549 * See do_execveat_common().
550 */
551 if (check_add_overflow(max(bprm->argc,
552 check_mul_overflow(ptr_size, sizeo
553 return -E2BIG;
554 if (limit <= ptr_size)
555 return -E2BIG;
556 limit -= ptr_size;
557
558 return bprm_set_stack_limit(bprm, limi
559 }
560
561 /*
562 * 'copy_strings()' copies argument/environmen
563 * processes's memory to the new process's sta
564 * ensures the destination page is created and
565 */
566 static int copy_strings(int argc, struct user_
567 struct linux_binprm *b
568 {
569 struct page *kmapped_page = NULL;
570 char *kaddr = NULL;
571 unsigned long kpos = 0;
572 int ret;
573
574 while (argc-- > 0) {
575 const char __user *str;
576 int len;
577 unsigned long pos;
578
579 ret = -EFAULT;
580 str = get_user_arg_ptr(argv, a
581 if (IS_ERR(str))
582 goto out;
583
584 len = strnlen_user(str, MAX_AR
585 if (!len)
586 goto out;
587
588 ret = -E2BIG;
589 if (!valid_arg_len(bprm, len))
590 goto out;
591
592 /* We're going to work our way
593 pos = bprm->p;
594 str += len;
595 bprm->p -= len;
596 if (bprm_hit_stack_limit(bprm)
597 goto out;
598
599 while (len > 0) {
600 int offset, bytes_to_c
601
602 if (fatal_signal_pendi
603 ret = -ERESTAR
604 goto out;
605 }
606 cond_resched();
607
608 offset = pos % PAGE_SI
609 if (offset == 0)
610 offset = PAGE_
611
612 bytes_to_copy = offset
613 if (bytes_to_copy > le
614 bytes_to_copy
615
616 offset -= bytes_to_cop
617 pos -= bytes_to_copy;
618 str -= bytes_to_copy;
619 len -= bytes_to_copy;
620
621 if (!kmapped_page || k
622 struct page *p
623
624 page = get_arg
625 if (!page) {
626 ret =
627 goto o
628 }
629
630 if (kmapped_pa
631 flush_
632 kunmap
633 put_ar
634 }
635 kmapped_page =
636 kaddr = kmap_l
637 kpos = pos & P
638 flush_arg_page
639 }
640 if (copy_from_user(kad
641 ret = -EFAULT;
642 goto out;
643 }
644 }
645 }
646 ret = 0;
647 out:
648 if (kmapped_page) {
649 flush_dcache_page(kmapped_page
650 kunmap_local(kaddr);
651 put_arg_page(kmapped_page);
652 }
653 return ret;
654 }
655
656 /*
657 * Copy and argument/environment string from t
658 */
659 int copy_string_kernel(const char *arg, struct
660 {
661 int len = strnlen(arg, MAX_ARG_STRLEN)
662 unsigned long pos = bprm->p;
663
664 if (len == 0)
665 return -EFAULT;
666 if (!valid_arg_len(bprm, len))
667 return -E2BIG;
668
669 /* We're going to work our way backwar
670 arg += len;
671 bprm->p -= len;
672 if (bprm_hit_stack_limit(bprm))
673 return -E2BIG;
674
675 while (len > 0) {
676 unsigned int bytes_to_copy = m
677 min_not_zero(o
678 struct page *page;
679
680 pos -= bytes_to_copy;
681 arg -= bytes_to_copy;
682 len -= bytes_to_copy;
683
684 page = get_arg_page(bprm, pos,
685 if (!page)
686 return -E2BIG;
687 flush_arg_page(bprm, pos & PAG
688 memcpy_to_page(page, offset_in
689 put_arg_page(page);
690 }
691
692 return 0;
693 }
694 EXPORT_SYMBOL(copy_string_kernel);
695
696 static int copy_strings_kernel(int argc, const
697 struct linux_bi
698 {
699 while (argc-- > 0) {
700 int ret = copy_string_kernel(a
701 if (ret < 0)
702 return ret;
703 if (fatal_signal_pending(curre
704 return -ERESTARTNOHAND
705 cond_resched();
706 }
707 return 0;
708 }
709
710 #ifdef CONFIG_MMU
711
712 /*
713 * Finalizes the stack vm_area_struct. The fla
714 * the stack is optionally relocated, and some
715 */
716 int setup_arg_pages(struct linux_binprm *bprm,
717 unsigned long stack_top,
718 int executable_stack)
719 {
720 unsigned long ret;
721 unsigned long stack_shift;
722 struct mm_struct *mm = current->mm;
723 struct vm_area_struct *vma = bprm->vma
724 struct vm_area_struct *prev = NULL;
725 unsigned long vm_flags;
726 unsigned long stack_base;
727 unsigned long stack_size;
728 unsigned long stack_expand;
729 unsigned long rlim_stack;
730 struct mmu_gather tlb;
731 struct vma_iterator vmi;
732
733 #ifdef CONFIG_STACK_GROWSUP
734 /* Limit stack size */
735 stack_base = bprm->rlim_stack.rlim_max
736
737 stack_base = calc_max_stack_size(stack
738
739 /* Add space for stack randomization.
740 if (current->flags & PF_RANDOMIZE)
741 stack_base += (STACK_RND_MASK
742
743 /* Make sure we didn't let the argumen
744 if (vma->vm_end - vma->vm_start > stac
745 return -ENOMEM;
746
747 stack_base = PAGE_ALIGN(stack_top - st
748
749 stack_shift = vma->vm_start - stack_ba
750 mm->arg_start = bprm->p - stack_shift;
751 bprm->p = vma->vm_end - stack_shift;
752 #else
753 stack_top = arch_align_stack(stack_top
754 stack_top = PAGE_ALIGN(stack_top);
755
756 if (unlikely(stack_top < mmap_min_addr
757 unlikely(vma->vm_end - vma->vm_sta
758 return -ENOMEM;
759
760 stack_shift = vma->vm_end - stack_top;
761
762 bprm->p -= stack_shift;
763 mm->arg_start = bprm->p;
764 #endif
765
766 if (bprm->loader)
767 bprm->loader -= stack_shift;
768 bprm->exec -= stack_shift;
769
770 if (mmap_write_lock_killable(mm))
771 return -EINTR;
772
773 vm_flags = VM_STACK_FLAGS;
774
775 /*
776 * Adjust stack execute permissions; e
777 * EXSTACK_ENABLE_X, disable for EXSTA
778 * (arch default) otherwise.
779 */
780 if (unlikely(executable_stack == EXSTA
781 vm_flags |= VM_EXEC;
782 else if (executable_stack == EXSTACK_D
783 vm_flags &= ~VM_EXEC;
784 vm_flags |= mm->def_flags;
785 vm_flags |= VM_STACK_INCOMPLETE_SETUP;
786
787 vma_iter_init(&vmi, mm, vma->vm_start)
788
789 tlb_gather_mmu(&tlb, mm);
790 ret = mprotect_fixup(&vmi, &tlb, vma,
791 vm_flags);
792 tlb_finish_mmu(&tlb);
793
794 if (ret)
795 goto out_unlock;
796 BUG_ON(prev != vma);
797
798 if (unlikely(vm_flags & VM_EXEC)) {
799 pr_warn_once("process '%pD4' s
800 bprm->file);
801 }
802
803 /* Move stack pages down in memory. */
804 if (stack_shift) {
805 /*
806 * During bprm_mm_init(), we c
807 * the binfmt code determines
808 * its final location.
809 */
810 ret = relocate_vma_down(vma, s
811 if (ret)
812 goto out_unlock;
813 }
814
815 /* mprotect_fixup is overkill to remov
816 vm_flags_clear(vma, VM_STACK_INCOMPLET
817
818 stack_expand = 131072UL; /* randomly 3
819 stack_size = vma->vm_end - vma->vm_sta
820 /*
821 * Align this down to a page boundary
822 * will align it up.
823 */
824 rlim_stack = bprm->rlim_stack.rlim_cur
825
826 stack_expand = min(rlim_stack, stack_s
827
828 #ifdef CONFIG_STACK_GROWSUP
829 stack_base = vma->vm_start + stack_exp
830 #else
831 stack_base = vma->vm_end - stack_expan
832 #endif
833 current->mm->start_stack = bprm->p;
834 ret = expand_stack_locked(vma, stack_b
835 if (ret)
836 ret = -EFAULT;
837
838 out_unlock:
839 mmap_write_unlock(mm);
840 return ret;
841 }
842 EXPORT_SYMBOL(setup_arg_pages);
843
844 #else
845
846 /*
847 * Transfer the program arguments and environm
848 * onto the stack. The provided stack pointer
849 */
850 int transfer_args_to_stack(struct linux_binprm
851 unsigned long *sp_l
852 {
853 unsigned long index, stop, sp;
854 int ret = 0;
855
856 stop = bprm->p >> PAGE_SHIFT;
857 sp = *sp_location;
858
859 for (index = MAX_ARG_PAGES - 1; index
860 unsigned int offset = index ==
861 char *src = kmap_local_page(bp
862 sp -= PAGE_SIZE - offset;
863 if (copy_to_user((void *) sp,
864 ret = -EFAULT;
865 kunmap_local(src);
866 if (ret)
867 goto out;
868 }
869
870 bprm->exec += *sp_location - MAX_ARG_P
871 *sp_location = sp;
872
873 out:
874 return ret;
875 }
876 EXPORT_SYMBOL(transfer_args_to_stack);
877
878 #endif /* CONFIG_MMU */
879
880 /*
881 * On success, caller must call do_close_execa
882 * struct file to close it.
883 */
884 static struct file *do_open_execat(int fd, str
885 {
886 struct file *file;
887 struct open_flags open_exec_flags = {
888 .open_flag = O_LARGEFILE | O_R
889 .acc_mode = MAY_EXEC,
890 .intent = LOOKUP_OPEN,
891 .lookup_flags = LOOKUP_FOLLOW,
892 };
893
894 if ((flags & ~(AT_SYMLINK_NOFOLLOW | A
895 return ERR_PTR(-EINVAL);
896 if (flags & AT_SYMLINK_NOFOLLOW)
897 open_exec_flags.lookup_flags &
898 if (flags & AT_EMPTY_PATH)
899 open_exec_flags.lookup_flags |
900
901 file = do_filp_open(fd, name, &open_ex
902 if (IS_ERR(file))
903 return file;
904
905 /*
906 * In the past the regular type check
907 * 633fb6ac3980 ("exec: move S_ISREG()
908 * an invariant that all non-regular f
909 */
910 if (WARN_ON_ONCE(!S_ISREG(file_inode(f
911 path_noexec(&file->f_path)) {
912 fput(file);
913 return ERR_PTR(-EACCES);
914 }
915
916 return file;
917 }
918
919 /**
920 * open_exec - Open a path name for execution
921 *
922 * @name: path name to open with the intent of
923 *
924 * Returns ERR_PTR on failure or allocated str
925 *
926 * As this is a wrapper for the internal do_op
927 * do_close_execat().
928 */
929 struct file *open_exec(const char *name)
930 {
931 struct filename *filename = getname_ke
932 struct file *f = ERR_CAST(filename);
933
934 if (!IS_ERR(filename)) {
935 f = do_open_execat(AT_FDCWD, f
936 putname(filename);
937 }
938 return f;
939 }
940 EXPORT_SYMBOL(open_exec);
941
942 #if defined(CONFIG_BINFMT_FLAT) || defined(CON
943 ssize_t read_code(struct file *file, unsigned
944 {
945 ssize_t res = vfs_read(file, (void __u
946 if (res > 0)
947 flush_icache_user_range(addr,
948 return res;
949 }
950 EXPORT_SYMBOL(read_code);
951 #endif
952
953 /*
954 * Maps the mm_struct mm into the current task
955 * On success, this function returns with exec
956 * held for writing.
957 */
958 static int exec_mmap(struct mm_struct *mm)
959 {
960 struct task_struct *tsk;
961 struct mm_struct *old_mm, *active_mm;
962 int ret;
963
964 /* Notify parent that we're no longer
965 tsk = current;
966 old_mm = current->mm;
967 exec_mm_release(tsk, old_mm);
968
969 ret = down_write_killable(&tsk->signal
970 if (ret)
971 return ret;
972
973 if (old_mm) {
974 /*
975 * If there is a pending fatal
976 * whose default action is to
977 * out and die instead of goin
978 */
979 ret = mmap_read_lock_killable(
980 if (ret) {
981 up_write(&tsk->signal-
982 return ret;
983 }
984 }
985
986 task_lock(tsk);
987 membarrier_exec_mmap(mm);
988
989 local_irq_disable();
990 active_mm = tsk->active_mm;
991 tsk->active_mm = mm;
992 tsk->mm = mm;
993 mm_init_cid(mm);
994 /*
995 * This prevents preemption while acti
996 * it and mm are being updated, which
997 * lazy tlb mm refcounting when these
998 * switches. Not all architectures can
999 * activate_mm yet.
1000 */
1001 if (!IS_ENABLED(CONFIG_ARCH_WANT_IRQS
1002 local_irq_enable();
1003 activate_mm(active_mm, mm);
1004 if (IS_ENABLED(CONFIG_ARCH_WANT_IRQS_
1005 local_irq_enable();
1006 lru_gen_add_mm(mm);
1007 task_unlock(tsk);
1008 lru_gen_use_mm(mm);
1009 if (old_mm) {
1010 mmap_read_unlock(old_mm);
1011 BUG_ON(active_mm != old_mm);
1012 setmax_mm_hiwater_rss(&tsk->s
1013 mm_update_next_owner(old_mm);
1014 mmput(old_mm);
1015 return 0;
1016 }
1017 mmdrop_lazy_tlb(active_mm);
1018 return 0;
1019 }
1020
1021 static int de_thread(struct task_struct *tsk)
1022 {
1023 struct signal_struct *sig = tsk->sign
1024 struct sighand_struct *oldsighand = t
1025 spinlock_t *lock = &oldsighand->siglo
1026
1027 if (thread_group_empty(tsk))
1028 goto no_thread_group;
1029
1030 /*
1031 * Kill all other threads in the thre
1032 */
1033 spin_lock_irq(lock);
1034 if ((sig->flags & SIGNAL_GROUP_EXIT)
1035 /*
1036 * Another group action in pr
1037 * return so that the signal
1038 */
1039 spin_unlock_irq(lock);
1040 return -EAGAIN;
1041 }
1042
1043 sig->group_exec_task = tsk;
1044 sig->notify_count = zap_other_threads
1045 if (!thread_group_leader(tsk))
1046 sig->notify_count--;
1047
1048 while (sig->notify_count) {
1049 __set_current_state(TASK_KILL
1050 spin_unlock_irq(lock);
1051 schedule();
1052 if (__fatal_signal_pending(ts
1053 goto killed;
1054 spin_lock_irq(lock);
1055 }
1056 spin_unlock_irq(lock);
1057
1058 /*
1059 * At this point all other threads ha
1060 * do is to wait for the thread group
1061 * and to assume its PID:
1062 */
1063 if (!thread_group_leader(tsk)) {
1064 struct task_struct *leader =
1065
1066 for (;;) {
1067 cgroup_threadgroup_ch
1068 write_lock_irq(&taskl
1069 /*
1070 * Do this under task
1071 * exit_notify() can'
1072 */
1073 sig->notify_count = -
1074 if (likely(leader->ex
1075 break;
1076 __set_current_state(T
1077 write_unlock_irq(&tas
1078 cgroup_threadgroup_ch
1079 schedule();
1080 if (__fatal_signal_pe
1081 goto killed;
1082 }
1083
1084 /*
1085 * The only record we have of
1086 * process, regardless of exe
1087 * All the past CPU time is a
1088 * from sister threads now de
1089 * exec, nothing survives fro
1090 * whose birth marks the true
1091 * When we take on its identi
1092 * also take its birthdate (a
1093 */
1094 tsk->start_time = leader->sta
1095 tsk->start_boottime = leader-
1096
1097 BUG_ON(!same_thread_group(lea
1098 /*
1099 * An exec() starts a new thr
1100 * TGID of the previous threa
1101 * two threads with a switche
1102 * the former thread group le
1103 */
1104
1105 /* Become a process group lea
1106 * The old leader becomes a t
1107 */
1108 exchange_tids(tsk, leader);
1109 transfer_pid(leader, tsk, PID
1110 transfer_pid(leader, tsk, PID
1111 transfer_pid(leader, tsk, PID
1112
1113 list_replace_rcu(&leader->tas
1114 list_replace_init(&leader->si
1115
1116 tsk->group_leader = tsk;
1117 leader->group_leader = tsk;
1118
1119 tsk->exit_signal = SIGCHLD;
1120 leader->exit_signal = -1;
1121
1122 BUG_ON(leader->exit_state !=
1123 leader->exit_state = EXIT_DEA
1124 /*
1125 * We are going to release_ta
1126 * the tracer can sleep in do
1127 * the tracer won't block aga
1128 */
1129 if (unlikely(leader->ptrace))
1130 __wake_up_parent(lead
1131 write_unlock_irq(&tasklist_lo
1132 cgroup_threadgroup_change_end
1133
1134 release_task(leader);
1135 }
1136
1137 sig->group_exec_task = NULL;
1138 sig->notify_count = 0;
1139
1140 no_thread_group:
1141 /* we have changed execution domain *
1142 tsk->exit_signal = SIGCHLD;
1143
1144 BUG_ON(!thread_group_leader(tsk));
1145 return 0;
1146
1147 killed:
1148 /* protects against exit_notify() and
1149 read_lock(&tasklist_lock);
1150 sig->group_exec_task = NULL;
1151 sig->notify_count = 0;
1152 read_unlock(&tasklist_lock);
1153 return -EAGAIN;
1154 }
1155
1156
1157 /*
1158 * This function makes sure the current proce
1159 * so that flush_signal_handlers can later re
1160 * disturbing other processes. (Other proces
1161 * table via the CLONE_SIGHAND option to clon
1162 */
1163 static int unshare_sighand(struct task_struct
1164 {
1165 struct sighand_struct *oldsighand = m
1166
1167 if (refcount_read(&oldsighand->count)
1168 struct sighand_struct *newsig
1169 /*
1170 * This ->sighand is shared w
1171 * but not CLONE_THREAD task,
1172 */
1173 newsighand = kmem_cache_alloc
1174 if (!newsighand)
1175 return -ENOMEM;
1176
1177 refcount_set(&newsighand->cou
1178
1179 write_lock_irq(&tasklist_lock
1180 spin_lock(&oldsighand->sigloc
1181 memcpy(newsighand->action, ol
1182 sizeof(newsighand->act
1183 rcu_assign_pointer(me->sighan
1184 spin_unlock(&oldsighand->sigl
1185 write_unlock_irq(&tasklist_lo
1186
1187 __cleanup_sighand(oldsighand)
1188 }
1189 return 0;
1190 }
1191
1192 char *__get_task_comm(char *buf, size_t buf_s
1193 {
1194 task_lock(tsk);
1195 /* Always NUL terminated and zero-pad
1196 strscpy_pad(buf, tsk->comm, buf_size)
1197 task_unlock(tsk);
1198 return buf;
1199 }
1200 EXPORT_SYMBOL_GPL(__get_task_comm);
1201
1202 /*
1203 * These functions flushes out all traces of
1204 * so that a new one can be started
1205 */
1206
1207 void __set_task_comm(struct task_struct *tsk,
1208 {
1209 task_lock(tsk);
1210 trace_task_rename(tsk, buf);
1211 strscpy_pad(tsk->comm, buf, sizeof(ts
1212 task_unlock(tsk);
1213 perf_event_comm(tsk, exec);
1214 }
1215
1216 /*
1217 * Calling this is the point of no return. No
1218 * seen by userspace since either the process
1219 * signal (via de_thread() or coredump), or w
1220 * (after exec_mmap()) by search_binary_handl
1221 */
1222 int begin_new_exec(struct linux_binprm * bprm
1223 {
1224 struct task_struct *me = current;
1225 int retval;
1226
1227 /* Once we are committed compute the
1228 retval = bprm_creds_from_file(bprm);
1229 if (retval)
1230 return retval;
1231
1232 /*
1233 * This tracepoint marks the point be
1234 * the current task is still unchange
1235 * no return). The later "sched_proce
1236 * the current task has successfully
1237 */
1238 trace_sched_prepare_exec(current, bpr
1239
1240 /*
1241 * Ensure all future errors are fatal
1242 */
1243 bprm->point_of_no_return = true;
1244
1245 /*
1246 * Make this the only thread in the t
1247 */
1248 retval = de_thread(me);
1249 if (retval)
1250 goto out;
1251
1252 /*
1253 * Cancel any io_uring activity acros
1254 */
1255 io_uring_task_cancel();
1256
1257 /* Ensure the files table is not shar
1258 retval = unshare_files();
1259 if (retval)
1260 goto out;
1261
1262 /*
1263 * Must be called _before_ exec_mmap(
1264 * not visible until then. Doing it h
1265 * we don't race against replace_mm_e
1266 */
1267 retval = set_mm_exe_file(bprm->mm, bp
1268 if (retval)
1269 goto out;
1270
1271 /* If the binary is not readable then
1272 would_dump(bprm, bprm->file);
1273 if (bprm->have_execfd)
1274 would_dump(bprm, bprm->execut
1275
1276 /*
1277 * Release all of the old mmap stuff
1278 */
1279 acct_arg_size(bprm, 0);
1280 retval = exec_mmap(bprm->mm);
1281 if (retval)
1282 goto out;
1283
1284 bprm->mm = NULL;
1285
1286 retval = exec_task_namespaces();
1287 if (retval)
1288 goto out_unlock;
1289
1290 #ifdef CONFIG_POSIX_TIMERS
1291 spin_lock_irq(&me->sighand->siglock);
1292 posix_cpu_timers_exit(me);
1293 spin_unlock_irq(&me->sighand->siglock
1294 exit_itimers(me);
1295 flush_itimer_signals();
1296 #endif
1297
1298 /*
1299 * Make the signal table private.
1300 */
1301 retval = unshare_sighand(me);
1302 if (retval)
1303 goto out_unlock;
1304
1305 me->flags &= ~(PF_RANDOMIZE | PF_FORK
1306 PF_NO
1307 flush_thread();
1308 me->personality &= ~bprm->per_clear;
1309
1310 clear_syscall_work_syscall_user_dispa
1311
1312 /*
1313 * We have to apply CLOEXEC before we
1314 * dumpable (in setup_new_exec) to av
1315 * trying to access the should-be-clo
1316 * undergoing exec(2).
1317 */
1318 do_close_on_exec(me->files);
1319
1320 if (bprm->secureexec) {
1321 /* Make sure parent cannot si
1322 me->pdeath_signal = 0;
1323
1324 /*
1325 * For secureexec, reset the
1326 * avoid bad behavior from th
1327 * happen before arch_pick_mm
1328 * RLIMIT_STACK, but after th
1329 * needing to clean up the ch
1330 */
1331 if (bprm->rlim_stack.rlim_cur
1332 bprm->rlim_stack.rlim
1333 }
1334
1335 me->sas_ss_sp = me->sas_ss_size = 0;
1336
1337 /*
1338 * Figure out dumpability. Note that
1339 * is wrong, but userspace depends on
1340 * bprm->secureexec instead.
1341 */
1342 if (bprm->interp_flags & BINPRM_FLAGS
1343 !(uid_eq(current_euid(), current_
1344 gid_eq(current_egid(), current_
1345 set_dumpable(current->mm, sui
1346 else
1347 set_dumpable(current->mm, SUI
1348
1349 perf_event_exec();
1350 __set_task_comm(me, kbasename(bprm->f
1351
1352 /* An exec changes our domain. We are
1353 group */
1354 WRITE_ONCE(me->self_exec_id, me->self
1355 flush_signal_handlers(me, 0);
1356
1357 retval = set_cred_ucounts(bprm->cred)
1358 if (retval < 0)
1359 goto out_unlock;
1360
1361 /*
1362 * install the new credentials for th
1363 */
1364 security_bprm_committing_creds(bprm);
1365
1366 commit_creds(bprm->cred);
1367 bprm->cred = NULL;
1368
1369 /*
1370 * Disable monitoring for regular use
1371 * when executing setuid binaries. Mu
1372 * wait until new credentials are com
1373 * by commit_creds() above
1374 */
1375 if (get_dumpable(me->mm) != SUID_DUMP
1376 perf_event_exit_task(me);
1377 /*
1378 * cred_guard_mutex must be held at l
1379 * ptrace_attach() from altering our
1380 * credentials; any time after this i
1381 */
1382 security_bprm_committed_creds(bprm);
1383
1384 /* Pass the opened binary to the inte
1385 if (bprm->have_execfd) {
1386 retval = get_unused_fd_flags(
1387 if (retval < 0)
1388 goto out_unlock;
1389 fd_install(retval, bprm->exec
1390 bprm->executable = NULL;
1391 bprm->execfd = retval;
1392 }
1393 return 0;
1394
1395 out_unlock:
1396 up_write(&me->signal->exec_update_loc
1397 if (!bprm->cred)
1398 mutex_unlock(&me->signal->cre
1399
1400 out:
1401 return retval;
1402 }
1403 EXPORT_SYMBOL(begin_new_exec);
1404
1405 void would_dump(struct linux_binprm *bprm, st
1406 {
1407 struct inode *inode = file_inode(file
1408 struct mnt_idmap *idmap = file_mnt_id
1409 if (inode_permission(idmap, inode, MA
1410 struct user_namespace *old, *
1411 bprm->interp_flags |= BINPRM_
1412
1413 /* Ensure mm->user_ns contain
1414 user_ns = old = bprm->mm->use
1415 while ((user_ns != &init_user
1416 !privileged_wrt_inode_
1417 user_ns = user_ns->pa
1418
1419 if (old != user_ns) {
1420 bprm->mm->user_ns = g
1421 put_user_ns(old);
1422 }
1423 }
1424 }
1425 EXPORT_SYMBOL(would_dump);
1426
1427 void setup_new_exec(struct linux_binprm * bpr
1428 {
1429 /* Setup things that can depend upon
1430 struct task_struct *me = current;
1431
1432 arch_pick_mmap_layout(me->mm, &bprm->
1433
1434 arch_setup_new_exec();
1435
1436 /* Set the new mm task size. We have
1437 * depend on TIF_32BIT which is only
1438 * some architectures like powerpc
1439 */
1440 me->mm->task_size = TASK_SIZE;
1441 up_write(&me->signal->exec_update_loc
1442 mutex_unlock(&me->signal->cred_guard_
1443 }
1444 EXPORT_SYMBOL(setup_new_exec);
1445
1446 /* Runs immediately before start_thread() tak
1447 void finalize_exec(struct linux_binprm *bprm)
1448 {
1449 /* Store any stack rlimit changes bef
1450 task_lock(current->group_leader);
1451 current->signal->rlim[RLIMIT_STACK] =
1452 task_unlock(current->group_leader);
1453 }
1454 EXPORT_SYMBOL(finalize_exec);
1455
1456 /*
1457 * Prepare credentials and lock ->cred_guard_
1458 * setup_new_exec() commits the new creds and
1459 * Or, if exec fails before, free_bprm() shou
1460 * and unlock.
1461 */
1462 static int prepare_bprm_creds(struct linux_bi
1463 {
1464 if (mutex_lock_interruptible(¤t
1465 return -ERESTARTNOINTR;
1466
1467 bprm->cred = prepare_exec_creds();
1468 if (likely(bprm->cred))
1469 return 0;
1470
1471 mutex_unlock(¤t->signal->cred_g
1472 return -ENOMEM;
1473 }
1474
1475 /* Matches do_open_execat() */
1476 static void do_close_execat(struct file *file
1477 {
1478 if (file)
1479 fput(file);
1480 }
1481
1482 static void free_bprm(struct linux_binprm *bp
1483 {
1484 if (bprm->mm) {
1485 acct_arg_size(bprm, 0);
1486 mmput(bprm->mm);
1487 }
1488 free_arg_pages(bprm);
1489 if (bprm->cred) {
1490 mutex_unlock(¤t->signal
1491 abort_creds(bprm->cred);
1492 }
1493 do_close_execat(bprm->file);
1494 if (bprm->executable)
1495 fput(bprm->executable);
1496 /* If a binfmt changed the interp, fr
1497 if (bprm->interp != bprm->filename)
1498 kfree(bprm->interp);
1499 kfree(bprm->fdpath);
1500 kfree(bprm);
1501 }
1502
1503 static struct linux_binprm *alloc_bprm(int fd
1504 {
1505 struct linux_binprm *bprm;
1506 struct file *file;
1507 int retval = -ENOMEM;
1508
1509 file = do_open_execat(fd, filename, f
1510 if (IS_ERR(file))
1511 return ERR_CAST(file);
1512
1513 bprm = kzalloc(sizeof(*bprm), GFP_KER
1514 if (!bprm) {
1515 do_close_execat(file);
1516 return ERR_PTR(-ENOMEM);
1517 }
1518
1519 bprm->file = file;
1520
1521 if (fd == AT_FDCWD || filename->name[
1522 bprm->filename = filename->na
1523 } else {
1524 if (filename->name[0] == '\0'
1525 bprm->fdpath = kaspri
1526 else
1527 bprm->fdpath = kaspri
1528
1529 if (!bprm->fdpath)
1530 goto out_free;
1531
1532 /*
1533 * Record that a name derived
1534 * inaccessible after exec.
1535 * choose to fail when the ex
1536 * interpreter and an open fi
1537 * the interpreter. This mak
1538 * than having the interprete
1539 * when it finds the executab
1540 */
1541 if (get_close_on_exec(fd))
1542 bprm->interp_flags |=
1543
1544 bprm->filename = bprm->fdpath
1545 }
1546 bprm->interp = bprm->filename;
1547
1548 retval = bprm_mm_init(bprm);
1549 if (!retval)
1550 return bprm;
1551
1552 out_free:
1553 free_bprm(bprm);
1554 return ERR_PTR(retval);
1555 }
1556
1557 int bprm_change_interp(const char *interp, st
1558 {
1559 /* If a binfmt changed the interp, fr
1560 if (bprm->interp != bprm->filename)
1561 kfree(bprm->interp);
1562 bprm->interp = kstrdup(interp, GFP_KE
1563 if (!bprm->interp)
1564 return -ENOMEM;
1565 return 0;
1566 }
1567 EXPORT_SYMBOL(bprm_change_interp);
1568
1569 /*
1570 * determine how safe it is to execute the pr
1571 * - the caller must hold ->cred_guard_mutex
1572 * PTRACE_ATTACH or seccomp thread-sync
1573 */
1574 static void check_unsafe_exec(struct linux_bi
1575 {
1576 struct task_struct *p = current, *t;
1577 unsigned n_fs;
1578
1579 if (p->ptrace)
1580 bprm->unsafe |= LSM_UNSAFE_PT
1581
1582 /*
1583 * This isn't strictly necessary, but
1584 * mess up.
1585 */
1586 if (task_no_new_privs(current))
1587 bprm->unsafe |= LSM_UNSAFE_NO
1588
1589 /*
1590 * If another task is sharing our fs,
1591 * suid exec because the differently
1592 * will be able to manipulate the cur
1593 * It would be nice to force an unsha
1594 */
1595 n_fs = 1;
1596 spin_lock(&p->fs->lock);
1597 rcu_read_lock();
1598 for_other_threads(p, t) {
1599 if (t->fs == p->fs)
1600 n_fs++;
1601 }
1602 rcu_read_unlock();
1603
1604 /* "users" and "in_exec" locked for c
1605 if (p->fs->users > n_fs)
1606 bprm->unsafe |= LSM_UNSAFE_SH
1607 else
1608 p->fs->in_exec = 1;
1609 spin_unlock(&p->fs->lock);
1610 }
1611
1612 static void bprm_fill_uid(struct linux_binprm
1613 {
1614 /* Handle suid and sgid on files */
1615 struct mnt_idmap *idmap;
1616 struct inode *inode = file_inode(file
1617 unsigned int mode;
1618 vfsuid_t vfsuid;
1619 vfsgid_t vfsgid;
1620 int err;
1621
1622 if (!mnt_may_suid(file->f_path.mnt))
1623 return;
1624
1625 if (task_no_new_privs(current))
1626 return;
1627
1628 mode = READ_ONCE(inode->i_mode);
1629 if (!(mode & (S_ISUID|S_ISGID)))
1630 return;
1631
1632 idmap = file_mnt_idmap(file);
1633
1634 /* Be careful if suid/sgid is set */
1635 inode_lock(inode);
1636
1637 /* Atomically reload and check mode/u
1638 mode = inode->i_mode;
1639 vfsuid = i_uid_into_vfsuid(idmap, ino
1640 vfsgid = i_gid_into_vfsgid(idmap, ino
1641 err = inode_permission(idmap, inode,
1642 inode_unlock(inode);
1643
1644 /* Did the exec bit vanish out from u
1645 if (err)
1646 return;
1647
1648 /* We ignore suid/sgid if there are n
1649 if (!vfsuid_has_mapping(bprm->cred->u
1650 !vfsgid_has_mapping(bprm->cred->u
1651 return;
1652
1653 if (mode & S_ISUID) {
1654 bprm->per_clear |= PER_CLEAR_
1655 bprm->cred->euid = vfsuid_int
1656 }
1657
1658 if ((mode & (S_ISGID | S_IXGRP)) == (
1659 bprm->per_clear |= PER_CLEAR_
1660 bprm->cred->egid = vfsgid_int
1661 }
1662 }
1663
1664 /*
1665 * Compute brpm->cred based upon the final bi
1666 */
1667 static int bprm_creds_from_file(struct linux_
1668 {
1669 /* Compute creds based on which file?
1670 struct file *file = bprm->execfd_cred
1671
1672 bprm_fill_uid(bprm, file);
1673 return security_bprm_creds_from_file(
1674 }
1675
1676 /*
1677 * Fill the binprm structure from the inode.
1678 * Read the first BINPRM_BUF_SIZE bytes
1679 *
1680 * This may be called multiple times for bina
1681 */
1682 static int prepare_binprm(struct linux_binprm
1683 {
1684 loff_t pos = 0;
1685
1686 memset(bprm->buf, 0, BINPRM_BUF_SIZE)
1687 return kernel_read(bprm->file, bprm->
1688 }
1689
1690 /*
1691 * Arguments are '\0' separated strings found
1692 * points to; chop off the first by relocatin
1693 * the first '\0' encountered.
1694 */
1695 int remove_arg_zero(struct linux_binprm *bprm
1696 {
1697 unsigned long offset;
1698 char *kaddr;
1699 struct page *page;
1700
1701 if (!bprm->argc)
1702 return 0;
1703
1704 do {
1705 offset = bprm->p & ~PAGE_MASK
1706 page = get_arg_page(bprm, bpr
1707 if (!page)
1708 return -EFAULT;
1709 kaddr = kmap_local_page(page)
1710
1711 for (; offset < PAGE_SIZE &&
1712 offset++, bpr
1713 ;
1714
1715 kunmap_local(kaddr);
1716 put_arg_page(page);
1717 } while (offset == PAGE_SIZE);
1718
1719 bprm->p++;
1720 bprm->argc--;
1721
1722 return 0;
1723 }
1724 EXPORT_SYMBOL(remove_arg_zero);
1725
1726 #define printable(c) (((c)=='\t') || ((c)=='\
1727 /*
1728 * cycle the list of binary formats handler,
1729 */
1730 static int search_binary_handler(struct linux
1731 {
1732 bool need_retry = IS_ENABLED(CONFIG_M
1733 struct linux_binfmt *fmt;
1734 int retval;
1735
1736 retval = prepare_binprm(bprm);
1737 if (retval < 0)
1738 return retval;
1739
1740 retval = security_bprm_check(bprm);
1741 if (retval)
1742 return retval;
1743
1744 retval = -ENOENT;
1745 retry:
1746 read_lock(&binfmt_lock);
1747 list_for_each_entry(fmt, &formats, lh
1748 if (!try_module_get(fmt->modu
1749 continue;
1750 read_unlock(&binfmt_lock);
1751
1752 retval = fmt->load_binary(bpr
1753
1754 read_lock(&binfmt_lock);
1755 put_binfmt(fmt);
1756 if (bprm->point_of_no_return
1757 read_unlock(&binfmt_l
1758 return retval;
1759 }
1760 }
1761 read_unlock(&binfmt_lock);
1762
1763 if (need_retry) {
1764 if (printable(bprm->buf[0]) &
1765 printable(bprm->buf[2]) &
1766 return retval;
1767 if (request_module("binfmt-%0
1768 return retval;
1769 need_retry = false;
1770 goto retry;
1771 }
1772
1773 return retval;
1774 }
1775
1776 /* binfmt handlers will call back into begin_
1777 static int exec_binprm(struct linux_binprm *b
1778 {
1779 pid_t old_pid, old_vpid;
1780 int ret, depth;
1781
1782 /* Need to fetch pid before load_bina
1783 old_pid = current->pid;
1784 rcu_read_lock();
1785 old_vpid = task_pid_nr_ns(current, ta
1786 rcu_read_unlock();
1787
1788 /* This allows 4 levels of binfmt rew
1789 for (depth = 0;; depth++) {
1790 struct file *exec;
1791 if (depth > 5)
1792 return -ELOOP;
1793
1794 ret = search_binary_handler(b
1795 if (ret < 0)
1796 return ret;
1797 if (!bprm->interpreter)
1798 break;
1799
1800 exec = bprm->file;
1801 bprm->file = bprm->interprete
1802 bprm->interpreter = NULL;
1803
1804 if (unlikely(bprm->have_execf
1805 if (bprm->executable)
1806 fput(exec);
1807 return -ENOEX
1808 }
1809 bprm->executable = ex
1810 } else
1811 fput(exec);
1812 }
1813
1814 audit_bprm(bprm);
1815 trace_sched_process_exec(current, old
1816 ptrace_event(PTRACE_EVENT_EXEC, old_v
1817 proc_exec_connector(current);
1818 return 0;
1819 }
1820
1821 static int bprm_execve(struct linux_binprm *b
1822 {
1823 int retval;
1824
1825 retval = prepare_bprm_creds(bprm);
1826 if (retval)
1827 return retval;
1828
1829 /*
1830 * Check for unsafe execution states
1831 * will call back into begin_new_exec
1832 * where setuid-ness is evaluated.
1833 */
1834 check_unsafe_exec(bprm);
1835 current->in_execve = 1;
1836 sched_mm_cid_before_execve(current);
1837
1838 sched_exec();
1839
1840 /* Set the unchanging part of bprm->c
1841 retval = security_bprm_creds_for_exec
1842 if (retval)
1843 goto out;
1844
1845 retval = ccs_exec_binprm(bprm);
1846 if (retval < 0)
1847 goto out;
1848
1849 sched_mm_cid_after_execve(current);
1850 /* execve succeeded */
1851 current->fs->in_exec = 0;
1852 current->in_execve = 0;
1853 rseq_execve(current);
1854 user_events_execve(current);
1855 acct_update_integrals(current);
1856 task_numa_free(current, false);
1857 return retval;
1858
1859 out:
1860 /*
1861 * If past the point of no return ens
1862 * returns to the userspace process.
1863 * signal if present otherwise termin
1864 * SIGSEGV.
1865 */
1866 if (bprm->point_of_no_return && !fata
1867 force_fatal_sig(SIGSEGV);
1868
1869 sched_mm_cid_after_execve(current);
1870 current->fs->in_exec = 0;
1871 current->in_execve = 0;
1872
1873 return retval;
1874 }
1875
1876 static int do_execveat_common(int fd, struct
1877 struct user_arg
1878 struct user_arg
1879 int flags)
1880 {
1881 struct linux_binprm *bprm;
1882 int retval;
1883
1884 if (IS_ERR(filename))
1885 return PTR_ERR(filename);
1886
1887 /*
1888 * We move the actual failure in case
1889 * set*uid() to execve() because too
1890 * don't check setuid() return code.
1891 * whether NPROC limit is still excee
1892 */
1893 if ((current->flags & PF_NPROC_EXCEED
1894 is_rlimit_overlimit(current_ucoun
1895 retval = -EAGAIN;
1896 goto out_ret;
1897 }
1898
1899 /* We're below the limit (still or ag
1900 * further execve() calls fail. */
1901 current->flags &= ~PF_NPROC_EXCEEDED;
1902
1903 bprm = alloc_bprm(fd, filename, flags
1904 if (IS_ERR(bprm)) {
1905 retval = PTR_ERR(bprm);
1906 goto out_ret;
1907 }
1908
1909 retval = count(argv, MAX_ARG_STRINGS)
1910 if (retval == 0)
1911 pr_warn_once("process '%s' la
1912 current->comm, b
1913 if (retval < 0)
1914 goto out_free;
1915 bprm->argc = retval;
1916
1917 retval = count(envp, MAX_ARG_STRINGS)
1918 if (retval < 0)
1919 goto out_free;
1920 bprm->envc = retval;
1921
1922 retval = bprm_stack_limits(bprm);
1923 if (retval < 0)
1924 goto out_free;
1925
1926 retval = copy_string_kernel(bprm->fil
1927 if (retval < 0)
1928 goto out_free;
1929 bprm->exec = bprm->p;
1930
1931 retval = copy_strings(bprm->envc, env
1932 if (retval < 0)
1933 goto out_free;
1934
1935 retval = copy_strings(bprm->argc, arg
1936 if (retval < 0)
1937 goto out_free;
1938
1939 /*
1940 * When argv is empty, add an empty s
1941 * ensure confused userspace programs
1942 * from argv[1] won't end up walking
1943 * bprm_stack_limits().
1944 */
1945 if (bprm->argc == 0) {
1946 retval = copy_string_kernel("
1947 if (retval < 0)
1948 goto out_free;
1949 bprm->argc = 1;
1950 }
1951
1952 retval = bprm_execve(bprm);
1953 out_free:
1954 free_bprm(bprm);
1955
1956 out_ret:
1957 putname(filename);
1958 return retval;
1959 }
1960
1961 int kernel_execve(const char *kernel_filename
1962 const char *const *argv, co
1963 {
1964 struct filename *filename;
1965 struct linux_binprm *bprm;
1966 int fd = AT_FDCWD;
1967 int retval;
1968
1969 /* It is non-sense for kernel threads
1970 if (WARN_ON_ONCE(current->flags & PF_
1971 return -EINVAL;
1972
1973 filename = getname_kernel(kernel_file
1974 if (IS_ERR(filename))
1975 return PTR_ERR(filename);
1976
1977 bprm = alloc_bprm(fd, filename, 0);
1978 if (IS_ERR(bprm)) {
1979 retval = PTR_ERR(bprm);
1980 goto out_ret;
1981 }
1982
1983 retval = count_strings_kernel(argv);
1984 if (WARN_ON_ONCE(retval == 0))
1985 retval = -EINVAL;
1986 if (retval < 0)
1987 goto out_free;
1988 bprm->argc = retval;
1989
1990 retval = count_strings_kernel(envp);
1991 if (retval < 0)
1992 goto out_free;
1993 bprm->envc = retval;
1994
1995 retval = bprm_stack_limits(bprm);
1996 if (retval < 0)
1997 goto out_free;
1998
1999 retval = copy_string_kernel(bprm->fil
2000 if (retval < 0)
2001 goto out_free;
2002 bprm->exec = bprm->p;
2003
2004 retval = copy_strings_kernel(bprm->en
2005 if (retval < 0)
2006 goto out_free;
2007
2008 retval = copy_strings_kernel(bprm->ar
2009 if (retval < 0)
2010 goto out_free;
2011
2012 retval = bprm_execve(bprm);
2013 out_free:
2014 free_bprm(bprm);
2015 out_ret:
2016 putname(filename);
2017 return retval;
2018 }
2019
2020 static int do_execve(struct filename *filenam
2021 const char __user *const __user *__ar
2022 const char __user *const __user *__en
2023 {
2024 struct user_arg_ptr argv = { .ptr.nat
2025 struct user_arg_ptr envp = { .ptr.nat
2026 return do_execveat_common(AT_FDCWD, f
2027 }
2028
2029 static int do_execveat(int fd, struct filenam
2030 const char __user *const __us
2031 const char __user *const __us
2032 int flags)
2033 {
2034 struct user_arg_ptr argv = { .ptr.nat
2035 struct user_arg_ptr envp = { .ptr.nat
2036
2037 return do_execveat_common(fd, filenam
2038 }
2039
2040 #ifdef CONFIG_COMPAT
2041 static int compat_do_execve(struct filename *
2042 const compat_uptr_t __user *__argv,
2043 const compat_uptr_t __user *__envp)
2044 {
2045 struct user_arg_ptr argv = {
2046 .is_compat = true,
2047 .ptr.compat = __argv,
2048 };
2049 struct user_arg_ptr envp = {
2050 .is_compat = true,
2051 .ptr.compat = __envp,
2052 };
2053 return do_execveat_common(AT_FDCWD, f
2054 }
2055
2056 static int compat_do_execveat(int fd, struct
2057 const compat_up
2058 const compat_up
2059 int flags)
2060 {
2061 struct user_arg_ptr argv = {
2062 .is_compat = true,
2063 .ptr.compat = __argv,
2064 };
2065 struct user_arg_ptr envp = {
2066 .is_compat = true,
2067 .ptr.compat = __envp,
2068 };
2069 return do_execveat_common(fd, filenam
2070 }
2071 #endif
2072
2073 void set_binfmt(struct linux_binfmt *new)
2074 {
2075 struct mm_struct *mm = current->mm;
2076
2077 if (mm->binfmt)
2078 module_put(mm->binfmt->module
2079
2080 mm->binfmt = new;
2081 if (new)
2082 __module_get(new->module);
2083 }
2084 EXPORT_SYMBOL(set_binfmt);
2085
2086 /*
2087 * set_dumpable stores three-value SUID_DUMP_
2088 */
2089 void set_dumpable(struct mm_struct *mm, int v
2090 {
2091 if (WARN_ON((unsigned)value > SUID_DU
2092 return;
2093
2094 set_mask_bits(&mm->flags, MMF_DUMPABL
2095 }
2096
2097 SYSCALL_DEFINE3(execve,
2098 const char __user *, filename
2099 const char __user *const __us
2100 const char __user *const __us
2101 {
2102 return do_execve(getname(filename), a
2103 }
2104
2105 SYSCALL_DEFINE5(execveat,
2106 int, fd, const char __user *,
2107 const char __user *const __us
2108 const char __user *const __us
2109 int, flags)
2110 {
2111 return do_execveat(fd,
2112 getname_uflags(fil
2113 argv, envp, flags)
2114 }
2115
2116 #ifdef CONFIG_COMPAT
2117 COMPAT_SYSCALL_DEFINE3(execve, const char __u
2118 const compat_uptr_t __user *, argv,
2119 const compat_uptr_t __user *, envp)
2120 {
2121 return compat_do_execve(getname(filen
2122 }
2123
2124 COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
2125 const char __user *, f
2126 const compat_uptr_t __
2127 const compat_uptr_t __
2128 int, flags)
2129 {
2130 return compat_do_execveat(fd,
2131 getname_ufl
2132 argv, envp,
2133 }
2134 #endif
2135
2136 #ifdef CONFIG_SYSCTL
2137
2138 static int proc_dointvec_minmax_coredump(cons
2139 void *buffer, size_t *lenp, l
2140 {
2141 int error = proc_dointvec_minmax(tabl
2142
2143 if (!error)
2144 validate_coredump_safety();
2145 return error;
2146 }
2147
2148 static struct ctl_table fs_exec_sysctls[] = {
2149 {
2150 .procname = "suid_dumpa
2151 .data = &suid_dumpa
2152 .maxlen = sizeof(int)
2153 .mode = 0644,
2154 .proc_handler = proc_dointv
2155 .extra1 = SYSCTL_ZERO
2156 .extra2 = SYSCTL_TWO,
2157 },
2158 };
2159
2160 static int __init init_fs_exec_sysctls(void)
2161 {
2162 register_sysctl_init("fs", fs_exec_sy
2163 return 0;
2164 }
2165
2166 fs_initcall(init_fs_exec_sysctls);
2167 #endif /* CONFIG_SYSCTL */
2168
2169 #ifdef CONFIG_EXEC_KUNIT_TEST
2170 #include "tests/exec_kunit.c"
2171 #endif
2172
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