Line data Source code
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 :
69 : #include <linux/uaccess.h>
70 : #include <asm/mmu_context.h>
71 : #include <asm/tlb.h>
72 :
73 : #include <trace/events/task.h>
74 : #include "internal.h"
75 :
76 : #include <trace/events/sched.h>
77 :
78 : static int bprm_creds_from_file(struct linux_binprm *bprm);
79 :
80 : int suid_dumpable = 0;
81 :
82 : static LIST_HEAD(formats);
83 : static DEFINE_RWLOCK(binfmt_lock);
84 :
85 2 : void __register_binfmt(struct linux_binfmt * fmt, int insert)
86 : {
87 2 : write_lock(&binfmt_lock);
88 2 : insert ? list_add(&fmt->lh, &formats) :
89 2 : list_add_tail(&fmt->lh, &formats);
90 2 : write_unlock(&binfmt_lock);
91 2 : }
92 :
93 : EXPORT_SYMBOL(__register_binfmt);
94 :
95 0 : void unregister_binfmt(struct linux_binfmt * fmt)
96 : {
97 0 : write_lock(&binfmt_lock);
98 0 : list_del(&fmt->lh);
99 0 : write_unlock(&binfmt_lock);
100 0 : }
101 :
102 : EXPORT_SYMBOL(unregister_binfmt);
103 :
104 : static inline void put_binfmt(struct linux_binfmt * fmt)
105 : {
106 0 : module_put(fmt->module);
107 : }
108 :
109 0 : bool path_noexec(const struct path *path)
110 : {
111 0 : return (path->mnt->mnt_flags & MNT_NOEXEC) ||
112 0 : (path->mnt->mnt_sb->s_iflags & SB_I_NOEXEC);
113 : }
114 :
115 : #ifdef CONFIG_USELIB
116 : /*
117 : * Note that a shared library must be both readable and executable due to
118 : * security reasons.
119 : *
120 : * Also note that we take the address to load from the file itself.
121 : */
122 : SYSCALL_DEFINE1(uselib, const char __user *, library)
123 : {
124 : struct linux_binfmt *fmt;
125 : struct file *file;
126 : struct filename *tmp = getname(library);
127 : int error = PTR_ERR(tmp);
128 : static const struct open_flags uselib_flags = {
129 : .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
130 : .acc_mode = MAY_READ | MAY_EXEC,
131 : .intent = LOOKUP_OPEN,
132 : .lookup_flags = LOOKUP_FOLLOW,
133 : };
134 :
135 : if (IS_ERR(tmp))
136 : goto out;
137 :
138 : file = do_filp_open(AT_FDCWD, tmp, &uselib_flags);
139 : putname(tmp);
140 : error = PTR_ERR(file);
141 : if (IS_ERR(file))
142 : goto out;
143 :
144 : /*
145 : * may_open() has already checked for this, so it should be
146 : * impossible to trip now. But we need to be extra cautious
147 : * and check again at the very end too.
148 : */
149 : error = -EACCES;
150 : if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
151 : path_noexec(&file->f_path)))
152 : goto exit;
153 :
154 : fsnotify_open(file);
155 :
156 : error = -ENOEXEC;
157 :
158 : read_lock(&binfmt_lock);
159 : list_for_each_entry(fmt, &formats, lh) {
160 : if (!fmt->load_shlib)
161 : continue;
162 : if (!try_module_get(fmt->module))
163 : continue;
164 : read_unlock(&binfmt_lock);
165 : error = fmt->load_shlib(file);
166 : read_lock(&binfmt_lock);
167 : put_binfmt(fmt);
168 : if (error != -ENOEXEC)
169 : break;
170 : }
171 : read_unlock(&binfmt_lock);
172 : exit:
173 : fput(file);
174 : out:
175 : return error;
176 : }
177 : #endif /* #ifdef CONFIG_USELIB */
178 :
179 : #ifdef CONFIG_MMU
180 : /*
181 : * The nascent bprm->mm is not visible until exec_mmap() but it can
182 : * use a lot of memory, account these pages in current->mm temporary
183 : * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
184 : * change the counter back via acct_arg_size(0).
185 : */
186 0 : static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
187 : {
188 0 : struct mm_struct *mm = current->mm;
189 0 : long diff = (long)(pages - bprm->vma_pages);
190 :
191 0 : if (!mm || !diff)
192 : return;
193 :
194 0 : bprm->vma_pages = pages;
195 0 : add_mm_counter(mm, MM_ANONPAGES, diff);
196 : }
197 :
198 0 : static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
199 : int write)
200 : {
201 : struct page *page;
202 : int ret;
203 0 : unsigned int gup_flags = 0;
204 :
205 : #ifdef CONFIG_STACK_GROWSUP
206 : if (write) {
207 : ret = expand_downwards(bprm->vma, pos);
208 : if (ret < 0)
209 : return NULL;
210 : }
211 : #endif
212 :
213 0 : if (write)
214 0 : gup_flags |= FOLL_WRITE;
215 :
216 : /*
217 : * We are doing an exec(). 'current' is the process
218 : * doing the exec and bprm->mm is the new process's mm.
219 : */
220 0 : mmap_read_lock(bprm->mm);
221 0 : ret = get_user_pages_remote(bprm->mm, pos, 1, gup_flags,
222 : &page, NULL, NULL);
223 0 : mmap_read_unlock(bprm->mm);
224 0 : if (ret <= 0)
225 : return NULL;
226 :
227 0 : if (write)
228 0 : acct_arg_size(bprm, vma_pages(bprm->vma));
229 :
230 0 : return page;
231 : }
232 :
233 : static void put_arg_page(struct page *page)
234 : {
235 0 : put_page(page);
236 : }
237 :
238 : static void free_arg_pages(struct linux_binprm *bprm)
239 : {
240 : }
241 :
242 : static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
243 : struct page *page)
244 : {
245 0 : flush_cache_page(bprm->vma, pos, page_to_pfn(page));
246 : }
247 :
248 0 : static int __bprm_mm_init(struct linux_binprm *bprm)
249 : {
250 : int err;
251 0 : struct vm_area_struct *vma = NULL;
252 0 : struct mm_struct *mm = bprm->mm;
253 :
254 0 : bprm->vma = vma = vm_area_alloc(mm);
255 0 : if (!vma)
256 : return -ENOMEM;
257 0 : vma_set_anonymous(vma);
258 :
259 0 : if (mmap_write_lock_killable(mm)) {
260 : err = -EINTR;
261 : goto err_free;
262 : }
263 :
264 : /*
265 : * Place the stack at the largest stack address the architecture
266 : * supports. Later, we'll move this to an appropriate place. We don't
267 : * use STACK_TOP because that can depend on attributes which aren't
268 : * configured yet.
269 : */
270 : BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
271 0 : vma->vm_end = STACK_TOP_MAX;
272 0 : vma->vm_start = vma->vm_end - PAGE_SIZE;
273 0 : vm_flags_init(vma, VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP);
274 0 : vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
275 :
276 0 : err = insert_vm_struct(mm, vma);
277 0 : if (err)
278 : goto err;
279 :
280 0 : mm->stack_vm = mm->total_vm = 1;
281 0 : mmap_write_unlock(mm);
282 0 : bprm->p = vma->vm_end - sizeof(void *);
283 0 : return 0;
284 : err:
285 : mmap_write_unlock(mm);
286 : err_free:
287 0 : bprm->vma = NULL;
288 0 : vm_area_free(vma);
289 0 : return err;
290 : }
291 :
292 : static bool valid_arg_len(struct linux_binprm *bprm, long len)
293 : {
294 0 : return len <= MAX_ARG_STRLEN;
295 : }
296 :
297 : #else
298 :
299 : static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
300 : {
301 : }
302 :
303 : static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
304 : int write)
305 : {
306 : struct page *page;
307 :
308 : page = bprm->page[pos / PAGE_SIZE];
309 : if (!page && write) {
310 : page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
311 : if (!page)
312 : return NULL;
313 : bprm->page[pos / PAGE_SIZE] = page;
314 : }
315 :
316 : return page;
317 : }
318 :
319 : static void put_arg_page(struct page *page)
320 : {
321 : }
322 :
323 : static void free_arg_page(struct linux_binprm *bprm, int i)
324 : {
325 : if (bprm->page[i]) {
326 : __free_page(bprm->page[i]);
327 : bprm->page[i] = NULL;
328 : }
329 : }
330 :
331 : static void free_arg_pages(struct linux_binprm *bprm)
332 : {
333 : int i;
334 :
335 : for (i = 0; i < MAX_ARG_PAGES; i++)
336 : free_arg_page(bprm, i);
337 : }
338 :
339 : static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
340 : struct page *page)
341 : {
342 : }
343 :
344 : static int __bprm_mm_init(struct linux_binprm *bprm)
345 : {
346 : bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
347 : return 0;
348 : }
349 :
350 : static bool valid_arg_len(struct linux_binprm *bprm, long len)
351 : {
352 : return len <= bprm->p;
353 : }
354 :
355 : #endif /* CONFIG_MMU */
356 :
357 : /*
358 : * Create a new mm_struct and populate it with a temporary stack
359 : * vm_area_struct. We don't have enough context at this point to set the stack
360 : * flags, permissions, and offset, so we use temporary values. We'll update
361 : * them later in setup_arg_pages().
362 : */
363 0 : static int bprm_mm_init(struct linux_binprm *bprm)
364 : {
365 : int err;
366 0 : struct mm_struct *mm = NULL;
367 :
368 0 : bprm->mm = mm = mm_alloc();
369 0 : err = -ENOMEM;
370 0 : if (!mm)
371 : goto err;
372 :
373 : /* Save current stack limit for all calculations made during exec. */
374 0 : task_lock(current->group_leader);
375 0 : bprm->rlim_stack = current->signal->rlim[RLIMIT_STACK];
376 0 : task_unlock(current->group_leader);
377 :
378 0 : err = __bprm_mm_init(bprm);
379 0 : if (err)
380 : goto err;
381 :
382 : return 0;
383 :
384 : err:
385 0 : if (mm) {
386 0 : bprm->mm = NULL;
387 : mmdrop(mm);
388 : }
389 :
390 : return err;
391 : }
392 :
393 : struct user_arg_ptr {
394 : #ifdef CONFIG_COMPAT
395 : bool is_compat;
396 : #endif
397 : union {
398 : const char __user *const __user *native;
399 : #ifdef CONFIG_COMPAT
400 : const compat_uptr_t __user *compat;
401 : #endif
402 : } ptr;
403 : };
404 :
405 0 : static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
406 : {
407 : const char __user *native;
408 :
409 : #ifdef CONFIG_COMPAT
410 : if (unlikely(argv.is_compat)) {
411 : compat_uptr_t compat;
412 :
413 : if (get_user(compat, argv.ptr.compat + nr))
414 : return ERR_PTR(-EFAULT);
415 :
416 : return compat_ptr(compat);
417 : }
418 : #endif
419 :
420 0 : if (get_user(native, argv.ptr.native + nr))
421 : return ERR_PTR(-EFAULT);
422 :
423 0 : return native;
424 : }
425 :
426 : /*
427 : * count() counts the number of strings in array ARGV.
428 : */
429 0 : static int count(struct user_arg_ptr argv, int max)
430 : {
431 0 : int i = 0;
432 :
433 0 : if (argv.ptr.native != NULL) {
434 0 : for (;;) {
435 0 : const char __user *p = get_user_arg_ptr(argv, i);
436 :
437 0 : if (!p)
438 : break;
439 :
440 0 : if (IS_ERR(p))
441 : return -EFAULT;
442 :
443 0 : if (i >= max)
444 : return -E2BIG;
445 0 : ++i;
446 :
447 0 : if (fatal_signal_pending(current))
448 : return -ERESTARTNOHAND;
449 0 : cond_resched();
450 : }
451 : }
452 : return i;
453 : }
454 :
455 0 : static int count_strings_kernel(const char *const *argv)
456 : {
457 : int i;
458 :
459 0 : if (!argv)
460 : return 0;
461 :
462 0 : for (i = 0; argv[i]; ++i) {
463 0 : if (i >= MAX_ARG_STRINGS)
464 : return -E2BIG;
465 0 : if (fatal_signal_pending(current))
466 : return -ERESTARTNOHAND;
467 0 : cond_resched();
468 : }
469 : return i;
470 : }
471 :
472 : static int bprm_stack_limits(struct linux_binprm *bprm)
473 : {
474 : unsigned long limit, ptr_size;
475 :
476 : /*
477 : * Limit to 1/4 of the max stack size or 3/4 of _STK_LIM
478 : * (whichever is smaller) for the argv+env strings.
479 : * This ensures that:
480 : * - the remaining binfmt code will not run out of stack space,
481 : * - the program will have a reasonable amount of stack left
482 : * to work from.
483 : */
484 0 : limit = _STK_LIM / 4 * 3;
485 0 : limit = min(limit, bprm->rlim_stack.rlim_cur / 4);
486 : /*
487 : * We've historically supported up to 32 pages (ARG_MAX)
488 : * of argument strings even with small stacks
489 : */
490 0 : limit = max_t(unsigned long, limit, ARG_MAX);
491 : /*
492 : * We must account for the size of all the argv and envp pointers to
493 : * the argv and envp strings, since they will also take up space in
494 : * the stack. They aren't stored until much later when we can't
495 : * signal to the parent that the child has run out of stack space.
496 : * Instead, calculate it here so it's possible to fail gracefully.
497 : *
498 : * In the case of argc = 0, make sure there is space for adding a
499 : * empty string (which will bump argc to 1), to ensure confused
500 : * userspace programs don't start processing from argv[1], thinking
501 : * argc can never be 0, to keep them from walking envp by accident.
502 : * See do_execveat_common().
503 : */
504 0 : ptr_size = (max(bprm->argc, 1) + bprm->envc) * sizeof(void *);
505 0 : if (limit <= ptr_size)
506 : return -E2BIG;
507 0 : limit -= ptr_size;
508 :
509 0 : bprm->argmin = bprm->p - limit;
510 : return 0;
511 : }
512 :
513 : /*
514 : * 'copy_strings()' copies argument/environment strings from the old
515 : * processes's memory to the new process's stack. The call to get_user_pages()
516 : * ensures the destination page is created and not swapped out.
517 : */
518 0 : static int copy_strings(int argc, struct user_arg_ptr argv,
519 : struct linux_binprm *bprm)
520 : {
521 0 : struct page *kmapped_page = NULL;
522 0 : char *kaddr = NULL;
523 0 : unsigned long kpos = 0;
524 : int ret;
525 :
526 0 : while (argc-- > 0) {
527 : const char __user *str;
528 : int len;
529 : unsigned long pos;
530 :
531 0 : ret = -EFAULT;
532 0 : str = get_user_arg_ptr(argv, argc);
533 0 : if (IS_ERR(str))
534 : goto out;
535 :
536 0 : len = strnlen_user(str, MAX_ARG_STRLEN);
537 0 : if (!len)
538 : goto out;
539 :
540 0 : ret = -E2BIG;
541 0 : if (!valid_arg_len(bprm, len))
542 : goto out;
543 :
544 : /* We're going to work our way backwards. */
545 0 : pos = bprm->p;
546 0 : str += len;
547 0 : bprm->p -= len;
548 : #ifdef CONFIG_MMU
549 0 : if (bprm->p < bprm->argmin)
550 : goto out;
551 : #endif
552 :
553 0 : while (len > 0) {
554 : int offset, bytes_to_copy;
555 :
556 0 : if (fatal_signal_pending(current)) {
557 : ret = -ERESTARTNOHAND;
558 : goto out;
559 : }
560 0 : cond_resched();
561 :
562 0 : offset = pos % PAGE_SIZE;
563 0 : if (offset == 0)
564 0 : offset = PAGE_SIZE;
565 :
566 0 : bytes_to_copy = offset;
567 0 : if (bytes_to_copy > len)
568 0 : bytes_to_copy = len;
569 :
570 0 : offset -= bytes_to_copy;
571 0 : pos -= bytes_to_copy;
572 0 : str -= bytes_to_copy;
573 0 : len -= bytes_to_copy;
574 :
575 0 : if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
576 : struct page *page;
577 :
578 0 : page = get_arg_page(bprm, pos, 1);
579 0 : if (!page) {
580 : ret = -E2BIG;
581 : goto out;
582 : }
583 :
584 0 : if (kmapped_page) {
585 0 : flush_dcache_page(kmapped_page);
586 0 : kunmap_local(kaddr);
587 : put_arg_page(kmapped_page);
588 : }
589 0 : kmapped_page = page;
590 0 : kaddr = kmap_local_page(kmapped_page);
591 0 : kpos = pos & PAGE_MASK;
592 0 : flush_arg_page(bprm, kpos, kmapped_page);
593 : }
594 0 : if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
595 : ret = -EFAULT;
596 : goto out;
597 : }
598 : }
599 : }
600 : ret = 0;
601 : out:
602 0 : if (kmapped_page) {
603 0 : flush_dcache_page(kmapped_page);
604 0 : kunmap_local(kaddr);
605 : put_arg_page(kmapped_page);
606 : }
607 0 : return ret;
608 : }
609 :
610 : /*
611 : * Copy and argument/environment string from the kernel to the processes stack.
612 : */
613 0 : int copy_string_kernel(const char *arg, struct linux_binprm *bprm)
614 : {
615 0 : int len = strnlen(arg, MAX_ARG_STRLEN) + 1 /* terminating NUL */;
616 0 : unsigned long pos = bprm->p;
617 :
618 0 : if (len == 0)
619 : return -EFAULT;
620 0 : if (!valid_arg_len(bprm, len))
621 : return -E2BIG;
622 :
623 : /* We're going to work our way backwards. */
624 0 : arg += len;
625 0 : bprm->p -= len;
626 0 : if (IS_ENABLED(CONFIG_MMU) && bprm->p < bprm->argmin)
627 : return -E2BIG;
628 :
629 0 : while (len > 0) {
630 0 : unsigned int bytes_to_copy = min_t(unsigned int, len,
631 : min_not_zero(offset_in_page(pos), PAGE_SIZE));
632 : struct page *page;
633 :
634 0 : pos -= bytes_to_copy;
635 0 : arg -= bytes_to_copy;
636 0 : len -= bytes_to_copy;
637 :
638 0 : page = get_arg_page(bprm, pos, 1);
639 0 : if (!page)
640 : return -E2BIG;
641 0 : flush_arg_page(bprm, pos & PAGE_MASK, page);
642 0 : memcpy_to_page(page, offset_in_page(pos), arg, bytes_to_copy);
643 : put_arg_page(page);
644 : }
645 :
646 : return 0;
647 : }
648 : EXPORT_SYMBOL(copy_string_kernel);
649 :
650 0 : static int copy_strings_kernel(int argc, const char *const *argv,
651 : struct linux_binprm *bprm)
652 : {
653 0 : while (argc-- > 0) {
654 0 : int ret = copy_string_kernel(argv[argc], bprm);
655 0 : if (ret < 0)
656 : return ret;
657 0 : if (fatal_signal_pending(current))
658 : return -ERESTARTNOHAND;
659 0 : cond_resched();
660 : }
661 : return 0;
662 : }
663 :
664 : #ifdef CONFIG_MMU
665 :
666 : /*
667 : * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
668 : * the binfmt code determines where the new stack should reside, we shift it to
669 : * its final location. The process proceeds as follows:
670 : *
671 : * 1) Use shift to calculate the new vma endpoints.
672 : * 2) Extend vma to cover both the old and new ranges. This ensures the
673 : * arguments passed to subsequent functions are consistent.
674 : * 3) Move vma's page tables to the new range.
675 : * 4) Free up any cleared pgd range.
676 : * 5) Shrink the vma to cover only the new range.
677 : */
678 0 : static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
679 : {
680 0 : struct mm_struct *mm = vma->vm_mm;
681 0 : unsigned long old_start = vma->vm_start;
682 0 : unsigned long old_end = vma->vm_end;
683 0 : unsigned long length = old_end - old_start;
684 0 : unsigned long new_start = old_start - shift;
685 0 : unsigned long new_end = old_end - shift;
686 0 : VMA_ITERATOR(vmi, mm, new_start);
687 : struct vm_area_struct *next;
688 : struct mmu_gather tlb;
689 :
690 0 : BUG_ON(new_start > new_end);
691 :
692 : /*
693 : * ensure there are no vmas between where we want to go
694 : * and where we are
695 : */
696 0 : if (vma != vma_next(&vmi))
697 : return -EFAULT;
698 :
699 : /*
700 : * cover the whole range: [new_start, old_end)
701 : */
702 0 : if (vma_expand(&vmi, vma, new_start, old_end, vma->vm_pgoff, NULL))
703 : return -ENOMEM;
704 :
705 : /*
706 : * move the page tables downwards, on failure we rely on
707 : * process cleanup to remove whatever mess we made.
708 : */
709 0 : if (length != move_page_tables(vma, old_start,
710 : vma, new_start, length, false))
711 : return -ENOMEM;
712 :
713 0 : lru_add_drain();
714 0 : tlb_gather_mmu(&tlb, mm);
715 0 : next = vma_next(&vmi);
716 0 : if (new_end > old_start) {
717 : /*
718 : * when the old and new regions overlap clear from new_end.
719 : */
720 0 : free_pgd_range(&tlb, new_end, old_end, new_end,
721 : next ? next->vm_start : USER_PGTABLES_CEILING);
722 : } else {
723 : /*
724 : * otherwise, clean from old_start; this is done to not touch
725 : * the address space in [new_end, old_start) some architectures
726 : * have constraints on va-space that make this illegal (IA64) -
727 : * for the others its just a little faster.
728 : */
729 0 : free_pgd_range(&tlb, old_start, old_end, new_end,
730 : next ? next->vm_start : USER_PGTABLES_CEILING);
731 : }
732 0 : tlb_finish_mmu(&tlb);
733 :
734 0 : vma_prev(&vmi);
735 : /* Shrink the vma to just the new range */
736 0 : return vma_shrink(&vmi, vma, new_start, new_end, vma->vm_pgoff);
737 : }
738 :
739 : /*
740 : * Finalizes the stack vm_area_struct. The flags and permissions are updated,
741 : * the stack is optionally relocated, and some extra space is added.
742 : */
743 0 : int setup_arg_pages(struct linux_binprm *bprm,
744 : unsigned long stack_top,
745 : int executable_stack)
746 : {
747 : unsigned long ret;
748 : unsigned long stack_shift;
749 0 : struct mm_struct *mm = current->mm;
750 0 : struct vm_area_struct *vma = bprm->vma;
751 0 : struct vm_area_struct *prev = NULL;
752 : unsigned long vm_flags;
753 : unsigned long stack_base;
754 : unsigned long stack_size;
755 : unsigned long stack_expand;
756 : unsigned long rlim_stack;
757 : struct mmu_gather tlb;
758 : struct vma_iterator vmi;
759 :
760 : #ifdef CONFIG_STACK_GROWSUP
761 : /* Limit stack size */
762 : stack_base = bprm->rlim_stack.rlim_max;
763 :
764 : stack_base = calc_max_stack_size(stack_base);
765 :
766 : /* Add space for stack randomization. */
767 : stack_base += (STACK_RND_MASK << PAGE_SHIFT);
768 :
769 : /* Make sure we didn't let the argument array grow too large. */
770 : if (vma->vm_end - vma->vm_start > stack_base)
771 : return -ENOMEM;
772 :
773 : stack_base = PAGE_ALIGN(stack_top - stack_base);
774 :
775 : stack_shift = vma->vm_start - stack_base;
776 : mm->arg_start = bprm->p - stack_shift;
777 : bprm->p = vma->vm_end - stack_shift;
778 : #else
779 0 : stack_top = arch_align_stack(stack_top);
780 0 : stack_top = PAGE_ALIGN(stack_top);
781 :
782 0 : if (unlikely(stack_top < mmap_min_addr) ||
783 0 : unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
784 : return -ENOMEM;
785 :
786 0 : stack_shift = vma->vm_end - stack_top;
787 :
788 0 : bprm->p -= stack_shift;
789 0 : mm->arg_start = bprm->p;
790 : #endif
791 :
792 0 : if (bprm->loader)
793 0 : bprm->loader -= stack_shift;
794 0 : bprm->exec -= stack_shift;
795 :
796 0 : if (mmap_write_lock_killable(mm))
797 : return -EINTR;
798 :
799 0 : vm_flags = VM_STACK_FLAGS;
800 :
801 : /*
802 : * Adjust stack execute permissions; explicitly enable for
803 : * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
804 : * (arch default) otherwise.
805 : */
806 0 : if (unlikely(executable_stack == EXSTACK_ENABLE_X))
807 : vm_flags |= VM_EXEC;
808 0 : else if (executable_stack == EXSTACK_DISABLE_X)
809 0 : vm_flags &= ~VM_EXEC;
810 0 : vm_flags |= mm->def_flags;
811 0 : vm_flags |= VM_STACK_INCOMPLETE_SETUP;
812 :
813 0 : vma_iter_init(&vmi, mm, vma->vm_start);
814 :
815 0 : tlb_gather_mmu(&tlb, mm);
816 0 : ret = mprotect_fixup(&vmi, &tlb, vma, &prev, vma->vm_start, vma->vm_end,
817 : vm_flags);
818 0 : tlb_finish_mmu(&tlb);
819 :
820 0 : if (ret)
821 : goto out_unlock;
822 0 : BUG_ON(prev != vma);
823 :
824 0 : if (unlikely(vm_flags & VM_EXEC)) {
825 0 : pr_warn_once("process '%pD4' started with executable stack\n",
826 : bprm->file);
827 : }
828 :
829 : /* Move stack pages down in memory. */
830 0 : if (stack_shift) {
831 0 : ret = shift_arg_pages(vma, stack_shift);
832 0 : if (ret)
833 : goto out_unlock;
834 : }
835 :
836 : /* mprotect_fixup is overkill to remove the temporary stack flags */
837 0 : vm_flags_clear(vma, VM_STACK_INCOMPLETE_SETUP);
838 :
839 0 : stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
840 0 : stack_size = vma->vm_end - vma->vm_start;
841 : /*
842 : * Align this down to a page boundary as expand_stack
843 : * will align it up.
844 : */
845 0 : rlim_stack = bprm->rlim_stack.rlim_cur & PAGE_MASK;
846 :
847 0 : stack_expand = min(rlim_stack, stack_size + stack_expand);
848 :
849 : #ifdef CONFIG_STACK_GROWSUP
850 : stack_base = vma->vm_start + stack_expand;
851 : #else
852 0 : stack_base = vma->vm_end - stack_expand;
853 : #endif
854 0 : current->mm->start_stack = bprm->p;
855 0 : ret = expand_stack(vma, stack_base);
856 0 : if (ret)
857 0 : ret = -EFAULT;
858 :
859 : out_unlock:
860 0 : mmap_write_unlock(mm);
861 0 : return ret;
862 : }
863 : EXPORT_SYMBOL(setup_arg_pages);
864 :
865 : #else
866 :
867 : /*
868 : * Transfer the program arguments and environment from the holding pages
869 : * onto the stack. The provided stack pointer is adjusted accordingly.
870 : */
871 : int transfer_args_to_stack(struct linux_binprm *bprm,
872 : unsigned long *sp_location)
873 : {
874 : unsigned long index, stop, sp;
875 : int ret = 0;
876 :
877 : stop = bprm->p >> PAGE_SHIFT;
878 : sp = *sp_location;
879 :
880 : for (index = MAX_ARG_PAGES - 1; index >= stop; index--) {
881 : unsigned int offset = index == stop ? bprm->p & ~PAGE_MASK : 0;
882 : char *src = kmap_local_page(bprm->page[index]) + offset;
883 : sp -= PAGE_SIZE - offset;
884 : if (copy_to_user((void *) sp, src, PAGE_SIZE - offset) != 0)
885 : ret = -EFAULT;
886 : kunmap_local(src);
887 : if (ret)
888 : goto out;
889 : }
890 :
891 : *sp_location = sp;
892 :
893 : out:
894 : return ret;
895 : }
896 : EXPORT_SYMBOL(transfer_args_to_stack);
897 :
898 : #endif /* CONFIG_MMU */
899 :
900 0 : static struct file *do_open_execat(int fd, struct filename *name, int flags)
901 : {
902 : struct file *file;
903 : int err;
904 0 : struct open_flags open_exec_flags = {
905 : .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
906 : .acc_mode = MAY_EXEC,
907 : .intent = LOOKUP_OPEN,
908 : .lookup_flags = LOOKUP_FOLLOW,
909 : };
910 :
911 0 : if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
912 : return ERR_PTR(-EINVAL);
913 0 : if (flags & AT_SYMLINK_NOFOLLOW)
914 0 : open_exec_flags.lookup_flags &= ~LOOKUP_FOLLOW;
915 0 : if (flags & AT_EMPTY_PATH)
916 0 : open_exec_flags.lookup_flags |= LOOKUP_EMPTY;
917 :
918 0 : file = do_filp_open(fd, name, &open_exec_flags);
919 0 : if (IS_ERR(file))
920 : goto out;
921 :
922 : /*
923 : * may_open() has already checked for this, so it should be
924 : * impossible to trip now. But we need to be extra cautious
925 : * and check again at the very end too.
926 : */
927 0 : err = -EACCES;
928 0 : if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
929 : path_noexec(&file->f_path)))
930 : goto exit;
931 :
932 0 : err = deny_write_access(file);
933 0 : if (err)
934 : goto exit;
935 :
936 0 : if (name->name[0] != '\0')
937 0 : fsnotify_open(file);
938 :
939 : out:
940 : return file;
941 :
942 : exit:
943 0 : fput(file);
944 0 : return ERR_PTR(err);
945 : }
946 :
947 0 : struct file *open_exec(const char *name)
948 : {
949 0 : struct filename *filename = getname_kernel(name);
950 0 : struct file *f = ERR_CAST(filename);
951 :
952 0 : if (!IS_ERR(filename)) {
953 0 : f = do_open_execat(AT_FDCWD, filename, 0);
954 0 : putname(filename);
955 : }
956 0 : return f;
957 : }
958 : EXPORT_SYMBOL(open_exec);
959 :
960 : #if defined(CONFIG_BINFMT_FLAT) || defined(CONFIG_BINFMT_ELF_FDPIC)
961 : ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
962 : {
963 : ssize_t res = vfs_read(file, (void __user *)addr, len, &pos);
964 : if (res > 0)
965 : flush_icache_user_range(addr, addr + len);
966 : return res;
967 : }
968 : EXPORT_SYMBOL(read_code);
969 : #endif
970 :
971 : /*
972 : * Maps the mm_struct mm into the current task struct.
973 : * On success, this function returns with exec_update_lock
974 : * held for writing.
975 : */
976 0 : static int exec_mmap(struct mm_struct *mm)
977 : {
978 : struct task_struct *tsk;
979 : struct mm_struct *old_mm, *active_mm;
980 : int ret;
981 :
982 : /* Notify parent that we're no longer interested in the old VM */
983 0 : tsk = current;
984 0 : old_mm = current->mm;
985 0 : exec_mm_release(tsk, old_mm);
986 : if (old_mm)
987 : sync_mm_rss(old_mm);
988 :
989 0 : ret = down_write_killable(&tsk->signal->exec_update_lock);
990 0 : if (ret)
991 : return ret;
992 :
993 0 : if (old_mm) {
994 : /*
995 : * If there is a pending fatal signal perhaps a signal
996 : * whose default action is to create a coredump get
997 : * out and die instead of going through with the exec.
998 : */
999 0 : ret = mmap_read_lock_killable(old_mm);
1000 0 : if (ret) {
1001 0 : up_write(&tsk->signal->exec_update_lock);
1002 0 : return ret;
1003 : }
1004 : }
1005 :
1006 0 : task_lock(tsk);
1007 0 : membarrier_exec_mmap(mm);
1008 :
1009 : local_irq_disable();
1010 0 : active_mm = tsk->active_mm;
1011 0 : tsk->active_mm = mm;
1012 0 : tsk->mm = mm;
1013 0 : mm_init_cid(mm);
1014 : /*
1015 : * This prevents preemption while active_mm is being loaded and
1016 : * it and mm are being updated, which could cause problems for
1017 : * lazy tlb mm refcounting when these are updated by context
1018 : * switches. Not all architectures can handle irqs off over
1019 : * activate_mm yet.
1020 : */
1021 : if (!IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
1022 : local_irq_enable();
1023 0 : activate_mm(active_mm, mm);
1024 : if (IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
1025 : local_irq_enable();
1026 0 : lru_gen_add_mm(mm);
1027 0 : task_unlock(tsk);
1028 0 : lru_gen_use_mm(mm);
1029 0 : if (old_mm) {
1030 0 : mmap_read_unlock(old_mm);
1031 0 : BUG_ON(active_mm != old_mm);
1032 0 : setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
1033 0 : mm_update_next_owner(old_mm);
1034 0 : mmput(old_mm);
1035 0 : return 0;
1036 : }
1037 : mmdrop(active_mm);
1038 : return 0;
1039 : }
1040 :
1041 0 : static int de_thread(struct task_struct *tsk)
1042 : {
1043 0 : struct signal_struct *sig = tsk->signal;
1044 0 : struct sighand_struct *oldsighand = tsk->sighand;
1045 0 : spinlock_t *lock = &oldsighand->siglock;
1046 :
1047 0 : if (thread_group_empty(tsk))
1048 : goto no_thread_group;
1049 :
1050 : /*
1051 : * Kill all other threads in the thread group.
1052 : */
1053 0 : spin_lock_irq(lock);
1054 0 : if ((sig->flags & SIGNAL_GROUP_EXIT) || sig->group_exec_task) {
1055 : /*
1056 : * Another group action in progress, just
1057 : * return so that the signal is processed.
1058 : */
1059 0 : spin_unlock_irq(lock);
1060 0 : return -EAGAIN;
1061 : }
1062 :
1063 0 : sig->group_exec_task = tsk;
1064 0 : sig->notify_count = zap_other_threads(tsk);
1065 0 : if (!thread_group_leader(tsk))
1066 0 : sig->notify_count--;
1067 :
1068 0 : while (sig->notify_count) {
1069 0 : __set_current_state(TASK_KILLABLE);
1070 0 : spin_unlock_irq(lock);
1071 0 : schedule();
1072 0 : if (__fatal_signal_pending(tsk))
1073 : goto killed;
1074 : spin_lock_irq(lock);
1075 : }
1076 0 : spin_unlock_irq(lock);
1077 :
1078 : /*
1079 : * At this point all other threads have exited, all we have to
1080 : * do is to wait for the thread group leader to become inactive,
1081 : * and to assume its PID:
1082 : */
1083 0 : if (!thread_group_leader(tsk)) {
1084 0 : struct task_struct *leader = tsk->group_leader;
1085 :
1086 : for (;;) {
1087 0 : cgroup_threadgroup_change_begin(tsk);
1088 0 : write_lock_irq(&tasklist_lock);
1089 : /*
1090 : * Do this under tasklist_lock to ensure that
1091 : * exit_notify() can't miss ->group_exec_task
1092 : */
1093 0 : sig->notify_count = -1;
1094 0 : if (likely(leader->exit_state))
1095 : break;
1096 0 : __set_current_state(TASK_KILLABLE);
1097 0 : write_unlock_irq(&tasklist_lock);
1098 0 : cgroup_threadgroup_change_end(tsk);
1099 0 : schedule();
1100 0 : if (__fatal_signal_pending(tsk))
1101 : goto killed;
1102 : }
1103 :
1104 : /*
1105 : * The only record we have of the real-time age of a
1106 : * process, regardless of execs it's done, is start_time.
1107 : * All the past CPU time is accumulated in signal_struct
1108 : * from sister threads now dead. But in this non-leader
1109 : * exec, nothing survives from the original leader thread,
1110 : * whose birth marks the true age of this process now.
1111 : * When we take on its identity by switching to its PID, we
1112 : * also take its birthdate (always earlier than our own).
1113 : */
1114 0 : tsk->start_time = leader->start_time;
1115 0 : tsk->start_boottime = leader->start_boottime;
1116 :
1117 0 : BUG_ON(!same_thread_group(leader, tsk));
1118 : /*
1119 : * An exec() starts a new thread group with the
1120 : * TGID of the previous thread group. Rehash the
1121 : * two threads with a switched PID, and release
1122 : * the former thread group leader:
1123 : */
1124 :
1125 : /* Become a process group leader with the old leader's pid.
1126 : * The old leader becomes a thread of the this thread group.
1127 : */
1128 0 : exchange_tids(tsk, leader);
1129 0 : transfer_pid(leader, tsk, PIDTYPE_TGID);
1130 0 : transfer_pid(leader, tsk, PIDTYPE_PGID);
1131 0 : transfer_pid(leader, tsk, PIDTYPE_SID);
1132 :
1133 0 : list_replace_rcu(&leader->tasks, &tsk->tasks);
1134 0 : list_replace_init(&leader->sibling, &tsk->sibling);
1135 :
1136 0 : tsk->group_leader = tsk;
1137 0 : leader->group_leader = tsk;
1138 :
1139 0 : tsk->exit_signal = SIGCHLD;
1140 0 : leader->exit_signal = -1;
1141 :
1142 0 : BUG_ON(leader->exit_state != EXIT_ZOMBIE);
1143 0 : leader->exit_state = EXIT_DEAD;
1144 :
1145 : /*
1146 : * We are going to release_task()->ptrace_unlink() silently,
1147 : * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
1148 : * the tracer won't block again waiting for this thread.
1149 : */
1150 0 : if (unlikely(leader->ptrace))
1151 0 : __wake_up_parent(leader, leader->parent);
1152 0 : write_unlock_irq(&tasklist_lock);
1153 0 : cgroup_threadgroup_change_end(tsk);
1154 :
1155 0 : release_task(leader);
1156 : }
1157 :
1158 0 : sig->group_exec_task = NULL;
1159 0 : sig->notify_count = 0;
1160 :
1161 : no_thread_group:
1162 : /* we have changed execution domain */
1163 0 : tsk->exit_signal = SIGCHLD;
1164 :
1165 0 : BUG_ON(!thread_group_leader(tsk));
1166 : return 0;
1167 :
1168 : killed:
1169 : /* protects against exit_notify() and __exit_signal() */
1170 0 : read_lock(&tasklist_lock);
1171 0 : sig->group_exec_task = NULL;
1172 0 : sig->notify_count = 0;
1173 0 : read_unlock(&tasklist_lock);
1174 0 : return -EAGAIN;
1175 : }
1176 :
1177 :
1178 : /*
1179 : * This function makes sure the current process has its own signal table,
1180 : * so that flush_signal_handlers can later reset the handlers without
1181 : * disturbing other processes. (Other processes might share the signal
1182 : * table via the CLONE_SIGHAND option to clone().)
1183 : */
1184 0 : static int unshare_sighand(struct task_struct *me)
1185 : {
1186 0 : struct sighand_struct *oldsighand = me->sighand;
1187 :
1188 0 : if (refcount_read(&oldsighand->count) != 1) {
1189 : struct sighand_struct *newsighand;
1190 : /*
1191 : * This ->sighand is shared with the CLONE_SIGHAND
1192 : * but not CLONE_THREAD task, switch to the new one.
1193 : */
1194 0 : newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1195 0 : if (!newsighand)
1196 : return -ENOMEM;
1197 :
1198 0 : refcount_set(&newsighand->count, 1);
1199 :
1200 0 : write_lock_irq(&tasklist_lock);
1201 0 : spin_lock(&oldsighand->siglock);
1202 0 : memcpy(newsighand->action, oldsighand->action,
1203 : sizeof(newsighand->action));
1204 0 : rcu_assign_pointer(me->sighand, newsighand);
1205 0 : spin_unlock(&oldsighand->siglock);
1206 0 : write_unlock_irq(&tasklist_lock);
1207 :
1208 0 : __cleanup_sighand(oldsighand);
1209 : }
1210 : return 0;
1211 : }
1212 :
1213 0 : char *__get_task_comm(char *buf, size_t buf_size, struct task_struct *tsk)
1214 : {
1215 0 : task_lock(tsk);
1216 : /* Always NUL terminated and zero-padded */
1217 0 : strscpy_pad(buf, tsk->comm, buf_size);
1218 0 : task_unlock(tsk);
1219 0 : return buf;
1220 : }
1221 : EXPORT_SYMBOL_GPL(__get_task_comm);
1222 :
1223 : /*
1224 : * These functions flushes out all traces of the currently running executable
1225 : * so that a new one can be started
1226 : */
1227 :
1228 339 : void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
1229 : {
1230 339 : task_lock(tsk);
1231 339 : trace_task_rename(tsk, buf);
1232 339 : strscpy_pad(tsk->comm, buf, sizeof(tsk->comm));
1233 339 : task_unlock(tsk);
1234 339 : perf_event_comm(tsk, exec);
1235 339 : }
1236 :
1237 : /*
1238 : * Calling this is the point of no return. None of the failures will be
1239 : * seen by userspace since either the process is already taking a fatal
1240 : * signal (via de_thread() or coredump), or will have SEGV raised
1241 : * (after exec_mmap()) by search_binary_handler (see below).
1242 : */
1243 0 : int begin_new_exec(struct linux_binprm * bprm)
1244 : {
1245 0 : struct task_struct *me = current;
1246 : int retval;
1247 :
1248 : /* Once we are committed compute the creds */
1249 0 : retval = bprm_creds_from_file(bprm);
1250 0 : if (retval)
1251 : return retval;
1252 :
1253 : /*
1254 : * Ensure all future errors are fatal.
1255 : */
1256 0 : bprm->point_of_no_return = true;
1257 :
1258 : /*
1259 : * Make this the only thread in the thread group.
1260 : */
1261 0 : retval = de_thread(me);
1262 0 : if (retval)
1263 : goto out;
1264 :
1265 : /*
1266 : * Cancel any io_uring activity across execve
1267 : */
1268 0 : io_uring_task_cancel();
1269 :
1270 : /* Ensure the files table is not shared. */
1271 0 : retval = unshare_files();
1272 0 : if (retval)
1273 : goto out;
1274 :
1275 : /*
1276 : * Must be called _before_ exec_mmap() as bprm->mm is
1277 : * not visible until then. This also enables the update
1278 : * to be lockless.
1279 : */
1280 0 : retval = set_mm_exe_file(bprm->mm, bprm->file);
1281 0 : if (retval)
1282 : goto out;
1283 :
1284 : /* If the binary is not readable then enforce mm->dumpable=0 */
1285 0 : would_dump(bprm, bprm->file);
1286 0 : if (bprm->have_execfd)
1287 0 : would_dump(bprm, bprm->executable);
1288 :
1289 : /*
1290 : * Release all of the old mmap stuff
1291 : */
1292 0 : acct_arg_size(bprm, 0);
1293 0 : retval = exec_mmap(bprm->mm);
1294 0 : if (retval)
1295 : goto out;
1296 :
1297 0 : bprm->mm = NULL;
1298 :
1299 0 : retval = exec_task_namespaces();
1300 0 : if (retval)
1301 : goto out_unlock;
1302 :
1303 : #ifdef CONFIG_POSIX_TIMERS
1304 0 : spin_lock_irq(&me->sighand->siglock);
1305 0 : posix_cpu_timers_exit(me);
1306 0 : spin_unlock_irq(&me->sighand->siglock);
1307 0 : exit_itimers(me);
1308 0 : flush_itimer_signals();
1309 : #endif
1310 :
1311 : /*
1312 : * Make the signal table private.
1313 : */
1314 0 : retval = unshare_sighand(me);
1315 0 : if (retval)
1316 : goto out_unlock;
1317 :
1318 0 : me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC |
1319 : PF_NOFREEZE | PF_NO_SETAFFINITY);
1320 0 : flush_thread();
1321 0 : me->personality &= ~bprm->per_clear;
1322 :
1323 0 : clear_syscall_work_syscall_user_dispatch(me);
1324 :
1325 : /*
1326 : * We have to apply CLOEXEC before we change whether the process is
1327 : * dumpable (in setup_new_exec) to avoid a race with a process in userspace
1328 : * trying to access the should-be-closed file descriptors of a process
1329 : * undergoing exec(2).
1330 : */
1331 0 : do_close_on_exec(me->files);
1332 :
1333 0 : if (bprm->secureexec) {
1334 : /* Make sure parent cannot signal privileged process. */
1335 0 : me->pdeath_signal = 0;
1336 :
1337 : /*
1338 : * For secureexec, reset the stack limit to sane default to
1339 : * avoid bad behavior from the prior rlimits. This has to
1340 : * happen before arch_pick_mmap_layout(), which examines
1341 : * RLIMIT_STACK, but after the point of no return to avoid
1342 : * needing to clean up the change on failure.
1343 : */
1344 0 : if (bprm->rlim_stack.rlim_cur > _STK_LIM)
1345 0 : bprm->rlim_stack.rlim_cur = _STK_LIM;
1346 : }
1347 :
1348 0 : me->sas_ss_sp = me->sas_ss_size = 0;
1349 :
1350 : /*
1351 : * Figure out dumpability. Note that this checking only of current
1352 : * is wrong, but userspace depends on it. This should be testing
1353 : * bprm->secureexec instead.
1354 : */
1355 0 : if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP ||
1356 0 : !(uid_eq(current_euid(), current_uid()) &&
1357 0 : gid_eq(current_egid(), current_gid())))
1358 0 : set_dumpable(current->mm, suid_dumpable);
1359 : else
1360 0 : set_dumpable(current->mm, SUID_DUMP_USER);
1361 :
1362 : perf_event_exec();
1363 0 : __set_task_comm(me, kbasename(bprm->filename), true);
1364 :
1365 : /* An exec changes our domain. We are no longer part of the thread
1366 : group */
1367 0 : WRITE_ONCE(me->self_exec_id, me->self_exec_id + 1);
1368 0 : flush_signal_handlers(me, 0);
1369 :
1370 0 : retval = set_cred_ucounts(bprm->cred);
1371 0 : if (retval < 0)
1372 : goto out_unlock;
1373 :
1374 : /*
1375 : * install the new credentials for this executable
1376 : */
1377 0 : security_bprm_committing_creds(bprm);
1378 :
1379 0 : commit_creds(bprm->cred);
1380 0 : bprm->cred = NULL;
1381 :
1382 : /*
1383 : * Disable monitoring for regular users
1384 : * when executing setuid binaries. Must
1385 : * wait until new credentials are committed
1386 : * by commit_creds() above
1387 : */
1388 0 : if (get_dumpable(me->mm) != SUID_DUMP_USER)
1389 : perf_event_exit_task(me);
1390 : /*
1391 : * cred_guard_mutex must be held at least to this point to prevent
1392 : * ptrace_attach() from altering our determination of the task's
1393 : * credentials; any time after this it may be unlocked.
1394 : */
1395 0 : security_bprm_committed_creds(bprm);
1396 :
1397 : /* Pass the opened binary to the interpreter. */
1398 0 : if (bprm->have_execfd) {
1399 0 : retval = get_unused_fd_flags(0);
1400 0 : if (retval < 0)
1401 : goto out_unlock;
1402 0 : fd_install(retval, bprm->executable);
1403 0 : bprm->executable = NULL;
1404 0 : bprm->execfd = retval;
1405 : }
1406 : return 0;
1407 :
1408 : out_unlock:
1409 0 : up_write(&me->signal->exec_update_lock);
1410 : out:
1411 : return retval;
1412 : }
1413 : EXPORT_SYMBOL(begin_new_exec);
1414 :
1415 0 : void would_dump(struct linux_binprm *bprm, struct file *file)
1416 : {
1417 0 : struct inode *inode = file_inode(file);
1418 0 : struct mnt_idmap *idmap = file_mnt_idmap(file);
1419 0 : if (inode_permission(idmap, inode, MAY_READ) < 0) {
1420 : struct user_namespace *old, *user_ns;
1421 0 : bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1422 :
1423 : /* Ensure mm->user_ns contains the executable */
1424 0 : user_ns = old = bprm->mm->user_ns;
1425 0 : while ((user_ns != &init_user_ns) &&
1426 0 : !privileged_wrt_inode_uidgid(user_ns, idmap, inode))
1427 0 : user_ns = user_ns->parent;
1428 :
1429 0 : if (old != user_ns) {
1430 0 : bprm->mm->user_ns = get_user_ns(user_ns);
1431 0 : put_user_ns(old);
1432 : }
1433 : }
1434 0 : }
1435 : EXPORT_SYMBOL(would_dump);
1436 :
1437 0 : void setup_new_exec(struct linux_binprm * bprm)
1438 : {
1439 : /* Setup things that can depend upon the personality */
1440 0 : struct task_struct *me = current;
1441 :
1442 0 : arch_pick_mmap_layout(me->mm, &bprm->rlim_stack);
1443 :
1444 : arch_setup_new_exec();
1445 :
1446 : /* Set the new mm task size. We have to do that late because it may
1447 : * depend on TIF_32BIT which is only updated in flush_thread() on
1448 : * some architectures like powerpc
1449 : */
1450 0 : me->mm->task_size = TASK_SIZE;
1451 0 : up_write(&me->signal->exec_update_lock);
1452 0 : mutex_unlock(&me->signal->cred_guard_mutex);
1453 0 : }
1454 : EXPORT_SYMBOL(setup_new_exec);
1455 :
1456 : /* Runs immediately before start_thread() takes over. */
1457 0 : void finalize_exec(struct linux_binprm *bprm)
1458 : {
1459 : /* Store any stack rlimit changes before starting thread. */
1460 0 : task_lock(current->group_leader);
1461 0 : current->signal->rlim[RLIMIT_STACK] = bprm->rlim_stack;
1462 0 : task_unlock(current->group_leader);
1463 0 : }
1464 : EXPORT_SYMBOL(finalize_exec);
1465 :
1466 : /*
1467 : * Prepare credentials and lock ->cred_guard_mutex.
1468 : * setup_new_exec() commits the new creds and drops the lock.
1469 : * Or, if exec fails before, free_bprm() should release ->cred
1470 : * and unlock.
1471 : */
1472 0 : static int prepare_bprm_creds(struct linux_binprm *bprm)
1473 : {
1474 0 : if (mutex_lock_interruptible(¤t->signal->cred_guard_mutex))
1475 : return -ERESTARTNOINTR;
1476 :
1477 0 : bprm->cred = prepare_exec_creds();
1478 0 : if (likely(bprm->cred))
1479 : return 0;
1480 :
1481 0 : mutex_unlock(¤t->signal->cred_guard_mutex);
1482 : return -ENOMEM;
1483 : }
1484 :
1485 0 : static void free_bprm(struct linux_binprm *bprm)
1486 : {
1487 0 : if (bprm->mm) {
1488 0 : acct_arg_size(bprm, 0);
1489 0 : mmput(bprm->mm);
1490 : }
1491 0 : free_arg_pages(bprm);
1492 0 : if (bprm->cred) {
1493 0 : mutex_unlock(¤t->signal->cred_guard_mutex);
1494 0 : abort_creds(bprm->cred);
1495 : }
1496 0 : if (bprm->file) {
1497 0 : allow_write_access(bprm->file);
1498 0 : fput(bprm->file);
1499 : }
1500 0 : if (bprm->executable)
1501 0 : fput(bprm->executable);
1502 : /* If a binfmt changed the interp, free it. */
1503 0 : if (bprm->interp != bprm->filename)
1504 0 : kfree(bprm->interp);
1505 0 : kfree(bprm->fdpath);
1506 0 : kfree(bprm);
1507 0 : }
1508 :
1509 0 : static struct linux_binprm *alloc_bprm(int fd, struct filename *filename)
1510 : {
1511 0 : struct linux_binprm *bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1512 0 : int retval = -ENOMEM;
1513 0 : if (!bprm)
1514 : goto out;
1515 :
1516 0 : if (fd == AT_FDCWD || filename->name[0] == '/') {
1517 0 : bprm->filename = filename->name;
1518 : } else {
1519 0 : if (filename->name[0] == '\0')
1520 0 : bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d", fd);
1521 : else
1522 0 : bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d/%s",
1523 : fd, filename->name);
1524 0 : if (!bprm->fdpath)
1525 : goto out_free;
1526 :
1527 0 : bprm->filename = bprm->fdpath;
1528 : }
1529 0 : bprm->interp = bprm->filename;
1530 :
1531 0 : retval = bprm_mm_init(bprm);
1532 0 : if (retval)
1533 : goto out_free;
1534 : return bprm;
1535 :
1536 : out_free:
1537 0 : free_bprm(bprm);
1538 : out:
1539 0 : return ERR_PTR(retval);
1540 : }
1541 :
1542 0 : int bprm_change_interp(const char *interp, struct linux_binprm *bprm)
1543 : {
1544 : /* If a binfmt changed the interp, free it first. */
1545 0 : if (bprm->interp != bprm->filename)
1546 0 : kfree(bprm->interp);
1547 0 : bprm->interp = kstrdup(interp, GFP_KERNEL);
1548 0 : if (!bprm->interp)
1549 : return -ENOMEM;
1550 0 : return 0;
1551 : }
1552 : EXPORT_SYMBOL(bprm_change_interp);
1553 :
1554 : /*
1555 : * determine how safe it is to execute the proposed program
1556 : * - the caller must hold ->cred_guard_mutex to protect against
1557 : * PTRACE_ATTACH or seccomp thread-sync
1558 : */
1559 0 : static void check_unsafe_exec(struct linux_binprm *bprm)
1560 : {
1561 0 : struct task_struct *p = current, *t;
1562 : unsigned n_fs;
1563 :
1564 0 : if (p->ptrace)
1565 0 : bprm->unsafe |= LSM_UNSAFE_PTRACE;
1566 :
1567 : /*
1568 : * This isn't strictly necessary, but it makes it harder for LSMs to
1569 : * mess up.
1570 : */
1571 0 : if (task_no_new_privs(current))
1572 0 : bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1573 :
1574 : /*
1575 : * If another task is sharing our fs, we cannot safely
1576 : * suid exec because the differently privileged task
1577 : * will be able to manipulate the current directory, etc.
1578 : * It would be nice to force an unshare instead...
1579 : */
1580 0 : t = p;
1581 0 : n_fs = 1;
1582 0 : spin_lock(&p->fs->lock);
1583 : rcu_read_lock();
1584 0 : while_each_thread(p, t) {
1585 0 : if (t->fs == p->fs)
1586 0 : n_fs++;
1587 : }
1588 : rcu_read_unlock();
1589 :
1590 0 : if (p->fs->users > n_fs)
1591 0 : bprm->unsafe |= LSM_UNSAFE_SHARE;
1592 : else
1593 0 : p->fs->in_exec = 1;
1594 0 : spin_unlock(&p->fs->lock);
1595 0 : }
1596 :
1597 0 : static void bprm_fill_uid(struct linux_binprm *bprm, struct file *file)
1598 : {
1599 : /* Handle suid and sgid on files */
1600 : struct mnt_idmap *idmap;
1601 0 : struct inode *inode = file_inode(file);
1602 : unsigned int mode;
1603 : vfsuid_t vfsuid;
1604 : vfsgid_t vfsgid;
1605 :
1606 0 : if (!mnt_may_suid(file->f_path.mnt))
1607 : return;
1608 :
1609 0 : if (task_no_new_privs(current))
1610 : return;
1611 :
1612 0 : mode = READ_ONCE(inode->i_mode);
1613 0 : if (!(mode & (S_ISUID|S_ISGID)))
1614 : return;
1615 :
1616 0 : idmap = file_mnt_idmap(file);
1617 :
1618 : /* Be careful if suid/sgid is set */
1619 0 : inode_lock(inode);
1620 :
1621 : /* reload atomically mode/uid/gid now that lock held */
1622 0 : mode = inode->i_mode;
1623 0 : vfsuid = i_uid_into_vfsuid(idmap, inode);
1624 0 : vfsgid = i_gid_into_vfsgid(idmap, inode);
1625 0 : inode_unlock(inode);
1626 :
1627 : /* We ignore suid/sgid if there are no mappings for them in the ns */
1628 0 : if (!vfsuid_has_mapping(bprm->cred->user_ns, vfsuid) ||
1629 0 : !vfsgid_has_mapping(bprm->cred->user_ns, vfsgid))
1630 : return;
1631 :
1632 0 : if (mode & S_ISUID) {
1633 0 : bprm->per_clear |= PER_CLEAR_ON_SETID;
1634 0 : bprm->cred->euid = vfsuid_into_kuid(vfsuid);
1635 : }
1636 :
1637 0 : if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1638 0 : bprm->per_clear |= PER_CLEAR_ON_SETID;
1639 0 : bprm->cred->egid = vfsgid_into_kgid(vfsgid);
1640 : }
1641 : }
1642 :
1643 : /*
1644 : * Compute brpm->cred based upon the final binary.
1645 : */
1646 0 : static int bprm_creds_from_file(struct linux_binprm *bprm)
1647 : {
1648 : /* Compute creds based on which file? */
1649 0 : struct file *file = bprm->execfd_creds ? bprm->executable : bprm->file;
1650 :
1651 0 : bprm_fill_uid(bprm, file);
1652 0 : return security_bprm_creds_from_file(bprm, file);
1653 : }
1654 :
1655 : /*
1656 : * Fill the binprm structure from the inode.
1657 : * Read the first BINPRM_BUF_SIZE bytes
1658 : *
1659 : * This may be called multiple times for binary chains (scripts for example).
1660 : */
1661 0 : static int prepare_binprm(struct linux_binprm *bprm)
1662 : {
1663 0 : loff_t pos = 0;
1664 :
1665 0 : memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1666 0 : return kernel_read(bprm->file, bprm->buf, BINPRM_BUF_SIZE, &pos);
1667 : }
1668 :
1669 : /*
1670 : * Arguments are '\0' separated strings found at the location bprm->p
1671 : * points to; chop off the first by relocating brpm->p to right after
1672 : * the first '\0' encountered.
1673 : */
1674 0 : int remove_arg_zero(struct linux_binprm *bprm)
1675 : {
1676 0 : int ret = 0;
1677 : unsigned long offset;
1678 : char *kaddr;
1679 : struct page *page;
1680 :
1681 0 : if (!bprm->argc)
1682 : return 0;
1683 :
1684 : do {
1685 0 : offset = bprm->p & ~PAGE_MASK;
1686 0 : page = get_arg_page(bprm, bprm->p, 0);
1687 0 : if (!page) {
1688 : ret = -EFAULT;
1689 : goto out;
1690 : }
1691 0 : kaddr = kmap_local_page(page);
1692 :
1693 0 : for (; offset < PAGE_SIZE && kaddr[offset];
1694 0 : offset++, bprm->p++)
1695 : ;
1696 :
1697 0 : kunmap_local(kaddr);
1698 0 : put_arg_page(page);
1699 0 : } while (offset == PAGE_SIZE);
1700 :
1701 0 : bprm->p++;
1702 0 : bprm->argc--;
1703 0 : ret = 0;
1704 :
1705 : out:
1706 : return ret;
1707 : }
1708 : EXPORT_SYMBOL(remove_arg_zero);
1709 :
1710 : #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1711 : /*
1712 : * cycle the list of binary formats handler, until one recognizes the image
1713 : */
1714 0 : static int search_binary_handler(struct linux_binprm *bprm)
1715 : {
1716 0 : bool need_retry = IS_ENABLED(CONFIG_MODULES);
1717 : struct linux_binfmt *fmt;
1718 : int retval;
1719 :
1720 0 : retval = prepare_binprm(bprm);
1721 0 : if (retval < 0)
1722 : return retval;
1723 :
1724 0 : retval = security_bprm_check(bprm);
1725 : if (retval)
1726 : return retval;
1727 :
1728 0 : retval = -ENOENT;
1729 : retry:
1730 0 : read_lock(&binfmt_lock);
1731 0 : list_for_each_entry(fmt, &formats, lh) {
1732 0 : if (!try_module_get(fmt->module))
1733 : continue;
1734 0 : read_unlock(&binfmt_lock);
1735 :
1736 0 : retval = fmt->load_binary(bprm);
1737 :
1738 0 : read_lock(&binfmt_lock);
1739 0 : put_binfmt(fmt);
1740 0 : if (bprm->point_of_no_return || (retval != -ENOEXEC)) {
1741 0 : read_unlock(&binfmt_lock);
1742 0 : return retval;
1743 : }
1744 : }
1745 0 : read_unlock(&binfmt_lock);
1746 :
1747 : if (need_retry) {
1748 : if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
1749 : printable(bprm->buf[2]) && printable(bprm->buf[3]))
1750 : return retval;
1751 : if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
1752 : return retval;
1753 : need_retry = false;
1754 : goto retry;
1755 : }
1756 :
1757 0 : return retval;
1758 : }
1759 :
1760 : /* binfmt handlers will call back into begin_new_exec() on success. */
1761 0 : static int exec_binprm(struct linux_binprm *bprm)
1762 : {
1763 : pid_t old_pid, old_vpid;
1764 : int ret, depth;
1765 :
1766 : /* Need to fetch pid before load_binary changes it */
1767 0 : old_pid = current->pid;
1768 : rcu_read_lock();
1769 0 : old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1770 : rcu_read_unlock();
1771 :
1772 : /* This allows 4 levels of binfmt rewrites before failing hard. */
1773 0 : for (depth = 0;; depth++) {
1774 : struct file *exec;
1775 0 : if (depth > 5)
1776 : return -ELOOP;
1777 :
1778 0 : ret = search_binary_handler(bprm);
1779 0 : if (ret < 0)
1780 : return ret;
1781 0 : if (!bprm->interpreter)
1782 : break;
1783 :
1784 0 : exec = bprm->file;
1785 0 : bprm->file = bprm->interpreter;
1786 0 : bprm->interpreter = NULL;
1787 :
1788 0 : allow_write_access(exec);
1789 0 : if (unlikely(bprm->have_execfd)) {
1790 0 : if (bprm->executable) {
1791 0 : fput(exec);
1792 0 : return -ENOEXEC;
1793 : }
1794 0 : bprm->executable = exec;
1795 : } else
1796 0 : fput(exec);
1797 : }
1798 :
1799 0 : audit_bprm(bprm);
1800 0 : trace_sched_process_exec(current, old_pid, bprm);
1801 0 : ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1802 0 : proc_exec_connector(current);
1803 0 : return 0;
1804 : }
1805 :
1806 : /*
1807 : * sys_execve() executes a new program.
1808 : */
1809 0 : static int bprm_execve(struct linux_binprm *bprm,
1810 : int fd, struct filename *filename, int flags)
1811 : {
1812 : struct file *file;
1813 : int retval;
1814 :
1815 0 : retval = prepare_bprm_creds(bprm);
1816 0 : if (retval)
1817 : return retval;
1818 :
1819 : /*
1820 : * Check for unsafe execution states before exec_binprm(), which
1821 : * will call back into begin_new_exec(), into bprm_creds_from_file(),
1822 : * where setuid-ness is evaluated.
1823 : */
1824 0 : check_unsafe_exec(bprm);
1825 0 : current->in_execve = 1;
1826 0 : sched_mm_cid_before_execve(current);
1827 :
1828 0 : file = do_open_execat(fd, filename, flags);
1829 0 : retval = PTR_ERR(file);
1830 0 : if (IS_ERR(file))
1831 : goto out_unmark;
1832 :
1833 : sched_exec();
1834 :
1835 0 : bprm->file = file;
1836 : /*
1837 : * Record that a name derived from an O_CLOEXEC fd will be
1838 : * inaccessible after exec. This allows the code in exec to
1839 : * choose to fail when the executable is not mmaped into the
1840 : * interpreter and an open file descriptor is not passed to
1841 : * the interpreter. This makes for a better user experience
1842 : * than having the interpreter start and then immediately fail
1843 : * when it finds the executable is inaccessible.
1844 : */
1845 0 : if (bprm->fdpath && get_close_on_exec(fd))
1846 0 : bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;
1847 :
1848 : /* Set the unchanging part of bprm->cred */
1849 0 : retval = security_bprm_creds_for_exec(bprm);
1850 : if (retval)
1851 : goto out;
1852 :
1853 0 : retval = exec_binprm(bprm);
1854 0 : if (retval < 0)
1855 : goto out;
1856 :
1857 0 : sched_mm_cid_after_execve(current);
1858 : /* execve succeeded */
1859 0 : current->fs->in_exec = 0;
1860 0 : current->in_execve = 0;
1861 0 : rseq_execve(current);
1862 0 : acct_update_integrals(current);
1863 0 : task_numa_free(current, false);
1864 0 : return retval;
1865 :
1866 : out:
1867 : /*
1868 : * If past the point of no return ensure the code never
1869 : * returns to the userspace process. Use an existing fatal
1870 : * signal if present otherwise terminate the process with
1871 : * SIGSEGV.
1872 : */
1873 0 : if (bprm->point_of_no_return && !fatal_signal_pending(current))
1874 0 : force_fatal_sig(SIGSEGV);
1875 :
1876 : out_unmark:
1877 0 : sched_mm_cid_after_execve(current);
1878 0 : current->fs->in_exec = 0;
1879 0 : current->in_execve = 0;
1880 :
1881 0 : return retval;
1882 : }
1883 :
1884 0 : static int do_execveat_common(int fd, struct filename *filename,
1885 : struct user_arg_ptr argv,
1886 : struct user_arg_ptr envp,
1887 : int flags)
1888 : {
1889 : struct linux_binprm *bprm;
1890 : int retval;
1891 :
1892 0 : if (IS_ERR(filename))
1893 0 : return PTR_ERR(filename);
1894 :
1895 : /*
1896 : * We move the actual failure in case of RLIMIT_NPROC excess from
1897 : * set*uid() to execve() because too many poorly written programs
1898 : * don't check setuid() return code. Here we additionally recheck
1899 : * whether NPROC limit is still exceeded.
1900 : */
1901 0 : if ((current->flags & PF_NPROC_EXCEEDED) &&
1902 0 : is_rlimit_overlimit(current_ucounts(), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
1903 : retval = -EAGAIN;
1904 : goto out_ret;
1905 : }
1906 :
1907 : /* We're below the limit (still or again), so we don't want to make
1908 : * further execve() calls fail. */
1909 0 : current->flags &= ~PF_NPROC_EXCEEDED;
1910 :
1911 0 : bprm = alloc_bprm(fd, filename);
1912 0 : if (IS_ERR(bprm)) {
1913 0 : retval = PTR_ERR(bprm);
1914 0 : goto out_ret;
1915 : }
1916 :
1917 0 : retval = count(argv, MAX_ARG_STRINGS);
1918 0 : if (retval == 0)
1919 0 : pr_warn_once("process '%s' launched '%s' with NULL argv: empty string added\n",
1920 : current->comm, bprm->filename);
1921 0 : if (retval < 0)
1922 : goto out_free;
1923 0 : bprm->argc = retval;
1924 :
1925 0 : retval = count(envp, MAX_ARG_STRINGS);
1926 0 : if (retval < 0)
1927 : goto out_free;
1928 0 : bprm->envc = retval;
1929 :
1930 0 : retval = bprm_stack_limits(bprm);
1931 0 : if (retval < 0)
1932 : goto out_free;
1933 :
1934 0 : retval = copy_string_kernel(bprm->filename, bprm);
1935 0 : if (retval < 0)
1936 : goto out_free;
1937 0 : bprm->exec = bprm->p;
1938 :
1939 0 : retval = copy_strings(bprm->envc, envp, bprm);
1940 0 : if (retval < 0)
1941 : goto out_free;
1942 :
1943 0 : retval = copy_strings(bprm->argc, argv, bprm);
1944 0 : if (retval < 0)
1945 : goto out_free;
1946 :
1947 : /*
1948 : * When argv is empty, add an empty string ("") as argv[0] to
1949 : * ensure confused userspace programs that start processing
1950 : * from argv[1] won't end up walking envp. See also
1951 : * bprm_stack_limits().
1952 : */
1953 0 : if (bprm->argc == 0) {
1954 0 : retval = copy_string_kernel("", bprm);
1955 0 : if (retval < 0)
1956 : goto out_free;
1957 0 : bprm->argc = 1;
1958 : }
1959 :
1960 0 : retval = bprm_execve(bprm, fd, filename, flags);
1961 : out_free:
1962 0 : free_bprm(bprm);
1963 :
1964 : out_ret:
1965 0 : putname(filename);
1966 0 : return retval;
1967 : }
1968 :
1969 0 : int kernel_execve(const char *kernel_filename,
1970 : const char *const *argv, const char *const *envp)
1971 : {
1972 : struct filename *filename;
1973 : struct linux_binprm *bprm;
1974 0 : int fd = AT_FDCWD;
1975 : int retval;
1976 :
1977 : /* It is non-sense for kernel threads to call execve */
1978 0 : if (WARN_ON_ONCE(current->flags & PF_KTHREAD))
1979 : return -EINVAL;
1980 :
1981 0 : filename = getname_kernel(kernel_filename);
1982 0 : if (IS_ERR(filename))
1983 0 : return PTR_ERR(filename);
1984 :
1985 0 : bprm = alloc_bprm(fd, filename);
1986 0 : if (IS_ERR(bprm)) {
1987 0 : retval = PTR_ERR(bprm);
1988 0 : goto out_ret;
1989 : }
1990 :
1991 0 : retval = count_strings_kernel(argv);
1992 0 : if (WARN_ON_ONCE(retval == 0))
1993 0 : retval = -EINVAL;
1994 0 : if (retval < 0)
1995 : goto out_free;
1996 0 : bprm->argc = retval;
1997 :
1998 0 : retval = count_strings_kernel(envp);
1999 0 : if (retval < 0)
2000 : goto out_free;
2001 0 : bprm->envc = retval;
2002 :
2003 0 : retval = bprm_stack_limits(bprm);
2004 0 : if (retval < 0)
2005 : goto out_free;
2006 :
2007 0 : retval = copy_string_kernel(bprm->filename, bprm);
2008 0 : if (retval < 0)
2009 : goto out_free;
2010 0 : bprm->exec = bprm->p;
2011 :
2012 0 : retval = copy_strings_kernel(bprm->envc, envp, bprm);
2013 0 : if (retval < 0)
2014 : goto out_free;
2015 :
2016 0 : retval = copy_strings_kernel(bprm->argc, argv, bprm);
2017 0 : if (retval < 0)
2018 : goto out_free;
2019 :
2020 0 : retval = bprm_execve(bprm, fd, filename, 0);
2021 : out_free:
2022 0 : free_bprm(bprm);
2023 : out_ret:
2024 0 : putname(filename);
2025 0 : return retval;
2026 : }
2027 :
2028 : static int do_execve(struct filename *filename,
2029 : const char __user *const __user *__argv,
2030 : const char __user *const __user *__envp)
2031 : {
2032 0 : struct user_arg_ptr argv = { .ptr.native = __argv };
2033 0 : struct user_arg_ptr envp = { .ptr.native = __envp };
2034 0 : return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
2035 : }
2036 :
2037 : static int do_execveat(int fd, struct filename *filename,
2038 : const char __user *const __user *__argv,
2039 : const char __user *const __user *__envp,
2040 : int flags)
2041 : {
2042 0 : struct user_arg_ptr argv = { .ptr.native = __argv };
2043 0 : struct user_arg_ptr envp = { .ptr.native = __envp };
2044 :
2045 0 : return do_execveat_common(fd, filename, argv, envp, flags);
2046 : }
2047 :
2048 : #ifdef CONFIG_COMPAT
2049 : static int compat_do_execve(struct filename *filename,
2050 : const compat_uptr_t __user *__argv,
2051 : const compat_uptr_t __user *__envp)
2052 : {
2053 : struct user_arg_ptr argv = {
2054 : .is_compat = true,
2055 : .ptr.compat = __argv,
2056 : };
2057 : struct user_arg_ptr envp = {
2058 : .is_compat = true,
2059 : .ptr.compat = __envp,
2060 : };
2061 : return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
2062 : }
2063 :
2064 : static int compat_do_execveat(int fd, struct filename *filename,
2065 : const compat_uptr_t __user *__argv,
2066 : const compat_uptr_t __user *__envp,
2067 : int flags)
2068 : {
2069 : struct user_arg_ptr argv = {
2070 : .is_compat = true,
2071 : .ptr.compat = __argv,
2072 : };
2073 : struct user_arg_ptr envp = {
2074 : .is_compat = true,
2075 : .ptr.compat = __envp,
2076 : };
2077 : return do_execveat_common(fd, filename, argv, envp, flags);
2078 : }
2079 : #endif
2080 :
2081 0 : void set_binfmt(struct linux_binfmt *new)
2082 : {
2083 0 : struct mm_struct *mm = current->mm;
2084 :
2085 0 : if (mm->binfmt)
2086 : module_put(mm->binfmt->module);
2087 :
2088 0 : mm->binfmt = new;
2089 : if (new)
2090 : __module_get(new->module);
2091 0 : }
2092 : EXPORT_SYMBOL(set_binfmt);
2093 :
2094 : /*
2095 : * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
2096 : */
2097 0 : void set_dumpable(struct mm_struct *mm, int value)
2098 : {
2099 0 : if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
2100 : return;
2101 :
2102 0 : set_mask_bits(&mm->flags, MMF_DUMPABLE_MASK, value);
2103 : }
2104 :
2105 0 : SYSCALL_DEFINE3(execve,
2106 : const char __user *, filename,
2107 : const char __user *const __user *, argv,
2108 : const char __user *const __user *, envp)
2109 : {
2110 0 : return do_execve(getname(filename), argv, envp);
2111 : }
2112 :
2113 0 : SYSCALL_DEFINE5(execveat,
2114 : int, fd, const char __user *, filename,
2115 : const char __user *const __user *, argv,
2116 : const char __user *const __user *, envp,
2117 : int, flags)
2118 : {
2119 0 : return do_execveat(fd,
2120 : getname_uflags(filename, flags),
2121 : argv, envp, flags);
2122 : }
2123 :
2124 : #ifdef CONFIG_COMPAT
2125 : COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
2126 : const compat_uptr_t __user *, argv,
2127 : const compat_uptr_t __user *, envp)
2128 : {
2129 : return compat_do_execve(getname(filename), argv, envp);
2130 : }
2131 :
2132 : COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
2133 : const char __user *, filename,
2134 : const compat_uptr_t __user *, argv,
2135 : const compat_uptr_t __user *, envp,
2136 : int, flags)
2137 : {
2138 : return compat_do_execveat(fd,
2139 : getname_uflags(filename, flags),
2140 : argv, envp, flags);
2141 : }
2142 : #endif
2143 :
2144 : #ifdef CONFIG_SYSCTL
2145 :
2146 0 : static int proc_dointvec_minmax_coredump(struct ctl_table *table, int write,
2147 : void *buffer, size_t *lenp, loff_t *ppos)
2148 : {
2149 0 : int error = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
2150 :
2151 0 : if (!error)
2152 0 : validate_coredump_safety();
2153 0 : return error;
2154 : }
2155 :
2156 : static struct ctl_table fs_exec_sysctls[] = {
2157 : {
2158 : .procname = "suid_dumpable",
2159 : .data = &suid_dumpable,
2160 : .maxlen = sizeof(int),
2161 : .mode = 0644,
2162 : .proc_handler = proc_dointvec_minmax_coredump,
2163 : .extra1 = SYSCTL_ZERO,
2164 : .extra2 = SYSCTL_TWO,
2165 : },
2166 : { }
2167 : };
2168 :
2169 1 : static int __init init_fs_exec_sysctls(void)
2170 : {
2171 1 : register_sysctl_init("fs", fs_exec_sysctls);
2172 1 : return 0;
2173 : }
2174 :
2175 : fs_initcall(init_fs_exec_sysctls);
2176 : #endif /* CONFIG_SYSCTL */
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