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1 | /* |
2 | * linux/fs/exec.c |
3 | * |
4 | * Copyright (C) 1991, 1992 Linus Torvalds |
5 | */ |
6 | |
7 | /* |
8 | * #!-checking implemented by tytso. |
9 | */ |
10 | /* |
11 | * Demand-loading implemented 01.12.91 - no need to read anything but |
12 | * the header into memory. The inode of the executable is put into |
13 | * "current->executable", and page faults do the actual loading. Clean. |
14 | * |
15 | * Once more I can proudly say that linux stood up to being changed: it |
16 | * was less than 2 hours work to get demand-loading completely implemented. |
17 | * |
18 | * Demand loading changed July 1993 by Eric Youngdale. Use mmap instead, |
19 | * current->executable is only used by the procfs. This allows a dispatch |
20 | * table to check for several different types of binary formats. We keep |
21 | * trying until we recognize the file or we run out of supported binary |
22 | * formats. |
23 | */ |
24 | |
25 | #include <linux/slab.h> |
26 | #include <linux/file.h> |
27 | #include <linux/fdtable.h> |
28 | #include <linux/mm.h> |
29 | #include <linux/vmacache.h> |
30 | #include <linux/stat.h> |
31 | #include <linux/fcntl.h> |
32 | #include <linux/swap.h> |
33 | #include <linux/string.h> |
34 | #include <linux/init.h> |
35 | #include <linux/pagemap.h> |
36 | #include <linux/perf_event.h> |
37 | #include <linux/highmem.h> |
38 | #include <linux/spinlock.h> |
39 | #include <linux/key.h> |
40 | #include <linux/personality.h> |
41 | #include <linux/binfmts.h> |
42 | #include <linux/utsname.h> |
43 | #include <linux/pid_namespace.h> |
44 | #include <linux/module.h> |
45 | #include <linux/namei.h> |
46 | #include <linux/mount.h> |
47 | #include <linux/security.h> |
48 | #include <linux/syscalls.h> |
49 | #include <linux/tsacct_kern.h> |
50 | #include <linux/cn_proc.h> |
51 | #include <linux/audit.h> |
52 | #include <linux/tracehook.h> |
53 | #include <linux/kmod.h> |
54 | #include <linux/fsnotify.h> |
55 | #include <linux/fs_struct.h> |
56 | #include <linux/pipe_fs_i.h> |
57 | #include <linux/oom.h> |
58 | #include <linux/compat.h> |
59 | |
60 | #include <asm/uaccess.h> |
61 | #include <asm/mmu_context.h> |
62 | #include <asm/tlb.h> |
63 | |
64 | #include <trace/events/task.h> |
65 | #include "internal.h" |
66 | |
67 | #include <trace/events/sched.h> |
68 | |
69 | int suid_dumpable = 0; |
70 | |
71 | static LIST_HEAD(formats); |
72 | static DEFINE_RWLOCK(binfmt_lock); |
73 | |
74 | void __register_binfmt(struct linux_binfmt * fmt, int insert) |
75 | { |
76 | BUG_ON(!fmt); |
77 | if (WARN_ON(!fmt->load_binary)) |
78 | return; |
79 | write_lock(&binfmt_lock); |
80 | insert ? list_add(&fmt->lh, &formats) : |
81 | list_add_tail(&fmt->lh, &formats); |
82 | write_unlock(&binfmt_lock); |
83 | } |
84 | |
85 | EXPORT_SYMBOL(__register_binfmt); |
86 | |
87 | void unregister_binfmt(struct linux_binfmt * fmt) |
88 | { |
89 | write_lock(&binfmt_lock); |
90 | list_del(&fmt->lh); |
91 | write_unlock(&binfmt_lock); |
92 | } |
93 | |
94 | EXPORT_SYMBOL(unregister_binfmt); |
95 | |
96 | static inline void put_binfmt(struct linux_binfmt * fmt) |
97 | { |
98 | module_put(fmt->module); |
99 | } |
100 | |
101 | #ifdef CONFIG_USELIB |
102 | /* |
103 | * Note that a shared library must be both readable and executable due to |
104 | * security reasons. |
105 | * |
106 | * Also note that we take the address to load from from the file itself. |
107 | */ |
108 | SYSCALL_DEFINE1(uselib, const char __user *, library) |
109 | { |
110 | struct linux_binfmt *fmt; |
111 | struct file *file; |
112 | struct filename *tmp = getname(library); |
113 | int error = PTR_ERR(tmp); |
114 | static const struct open_flags uselib_flags = { |
115 | .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, |
116 | .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN, |
117 | .intent = LOOKUP_OPEN, |
118 | .lookup_flags = LOOKUP_FOLLOW, |
119 | }; |
120 | |
121 | if (IS_ERR(tmp)) |
122 | goto out; |
123 | |
124 | file = do_filp_open(AT_FDCWD, tmp, &uselib_flags); |
125 | putname(tmp); |
126 | error = PTR_ERR(file); |
127 | if (IS_ERR(file)) |
128 | goto out; |
129 | |
130 | error = -EINVAL; |
131 | if (!S_ISREG(file_inode(file)->i_mode)) |
132 | goto exit; |
133 | |
134 | error = -EACCES; |
135 | if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) |
136 | goto exit; |
137 | |
138 | fsnotify_open(file); |
139 | |
140 | error = -ENOEXEC; |
141 | |
142 | read_lock(&binfmt_lock); |
143 | list_for_each_entry(fmt, &formats, lh) { |
144 | if (!fmt->load_shlib) |
145 | continue; |
146 | if (!try_module_get(fmt->module)) |
147 | continue; |
148 | read_unlock(&binfmt_lock); |
149 | error = fmt->load_shlib(file); |
150 | read_lock(&binfmt_lock); |
151 | put_binfmt(fmt); |
152 | if (error != -ENOEXEC) |
153 | break; |
154 | } |
155 | read_unlock(&binfmt_lock); |
156 | exit: |
157 | fput(file); |
158 | out: |
159 | return error; |
160 | } |
161 | #endif /* #ifdef CONFIG_USELIB */ |
162 | |
163 | #ifdef CONFIG_MMU |
164 | /* |
165 | * The nascent bprm->mm is not visible until exec_mmap() but it can |
166 | * use a lot of memory, account these pages in current->mm temporary |
167 | * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we |
168 | * change the counter back via acct_arg_size(0). |
169 | */ |
170 | static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) |
171 | { |
172 | struct mm_struct *mm = current->mm; |
173 | long diff = (long)(pages - bprm->vma_pages); |
174 | |
175 | if (!mm || !diff) |
176 | return; |
177 | |
178 | bprm->vma_pages = pages; |
179 | add_mm_counter(mm, MM_ANONPAGES, diff); |
180 | } |
181 | |
182 | static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, |
183 | int write) |
184 | { |
185 | struct page *page; |
186 | int ret; |
187 | |
188 | #ifdef CONFIG_STACK_GROWSUP |
189 | if (write) { |
190 | ret = expand_downwards(bprm->vma, pos); |
191 | if (ret < 0) |
192 | return NULL; |
193 | } |
194 | #endif |
195 | ret = get_user_pages(current, bprm->mm, pos, |
196 | 1, write, 1, &page, NULL); |
197 | if (ret <= 0) |
198 | return NULL; |
199 | |
200 | if (write) { |
201 | unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start; |
202 | struct rlimit *rlim; |
203 | |
204 | acct_arg_size(bprm, size / PAGE_SIZE); |
205 | |
206 | /* |
207 | * We've historically supported up to 32 pages (ARG_MAX) |
208 | * of argument strings even with small stacks |
209 | */ |
210 | if (size <= ARG_MAX) |
211 | return page; |
212 | |
213 | /* |
214 | * Limit to 1/4-th the stack size for the argv+env strings. |
215 | * This ensures that: |
216 | * - the remaining binfmt code will not run out of stack space, |
217 | * - the program will have a reasonable amount of stack left |
218 | * to work from. |
219 | */ |
220 | rlim = current->signal->rlim; |
221 | if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) { |
222 | put_page(page); |
223 | return NULL; |
224 | } |
225 | } |
226 | |
227 | return page; |
228 | } |
229 | |
230 | static void put_arg_page(struct page *page) |
231 | { |
232 | put_page(page); |
233 | } |
234 | |
235 | static void free_arg_page(struct linux_binprm *bprm, int i) |
236 | { |
237 | } |
238 | |
239 | static void free_arg_pages(struct linux_binprm *bprm) |
240 | { |
241 | } |
242 | |
243 | static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, |
244 | struct page *page) |
245 | { |
246 | flush_cache_page(bprm->vma, pos, page_to_pfn(page)); |
247 | } |
248 | |
249 | static int __bprm_mm_init(struct linux_binprm *bprm) |
250 | { |
251 | int err; |
252 | struct vm_area_struct *vma = NULL; |
253 | struct mm_struct *mm = bprm->mm; |
254 | |
255 | bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); |
256 | if (!vma) |
257 | return -ENOMEM; |
258 | |
259 | down_write(&mm->mmap_sem); |
260 | vma->vm_mm = mm; |
261 | |
262 | /* |
263 | * Place the stack at the largest stack address the architecture |
264 | * supports. Later, we'll move this to an appropriate place. We don't |
265 | * use STACK_TOP because that can depend on attributes which aren't |
266 | * configured yet. |
267 | */ |
268 | BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP); |
269 | vma->vm_end = STACK_TOP_MAX; |
270 | vma->vm_start = vma->vm_end - PAGE_SIZE; |
271 | vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP; |
272 | vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); |
273 | INIT_LIST_HEAD(&vma->anon_vma_chain); |
274 | |
275 | err = insert_vm_struct(mm, vma); |
276 | if (err) |
277 | goto err; |
278 | |
279 | mm->stack_vm = mm->total_vm = 1; |
280 | up_write(&mm->mmap_sem); |
281 | bprm->p = vma->vm_end - sizeof(void *); |
282 | return 0; |
283 | err: |
284 | up_write(&mm->mmap_sem); |
285 | bprm->vma = NULL; |
286 | kmem_cache_free(vm_area_cachep, vma); |
287 | return err; |
288 | } |
289 | |
290 | static bool valid_arg_len(struct linux_binprm *bprm, long len) |
291 | { |
292 | return len <= MAX_ARG_STRLEN; |
293 | } |
294 | |
295 | #else |
296 | |
297 | static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) |
298 | { |
299 | } |
300 | |
301 | static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, |
302 | int write) |
303 | { |
304 | struct page *page; |
305 | |
306 | page = bprm->page[pos / PAGE_SIZE]; |
307 | if (!page && write) { |
308 | page = alloc_page(GFP_HIGHUSER|__GFP_ZERO); |
309 | if (!page) |
310 | return NULL; |
311 | bprm->page[pos / PAGE_SIZE] = page; |
312 | } |
313 | |
314 | return page; |
315 | } |
316 | |
317 | static void put_arg_page(struct page *page) |
318 | { |
319 | } |
320 | |
321 | static void free_arg_page(struct linux_binprm *bprm, int i) |
322 | { |
323 | if (bprm->page[i]) { |
324 | __free_page(bprm->page[i]); |
325 | bprm->page[i] = NULL; |
326 | } |
327 | } |
328 | |
329 | static void free_arg_pages(struct linux_binprm *bprm) |
330 | { |
331 | int i; |
332 | |
333 | for (i = 0; i < MAX_ARG_PAGES; i++) |
334 | free_arg_page(bprm, i); |
335 | } |
336 | |
337 | static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, |
338 | struct page *page) |
339 | { |
340 | } |
341 | |
342 | static int __bprm_mm_init(struct linux_binprm *bprm) |
343 | { |
344 | bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *); |
345 | return 0; |
346 | } |
347 | |
348 | static bool valid_arg_len(struct linux_binprm *bprm, long len) |
349 | { |
350 | return len <= bprm->p; |
351 | } |
352 | |
353 | #endif /* CONFIG_MMU */ |
354 | |
355 | /* |
356 | * Create a new mm_struct and populate it with a temporary stack |
357 | * vm_area_struct. We don't have enough context at this point to set the stack |
358 | * flags, permissions, and offset, so we use temporary values. We'll update |
359 | * them later in setup_arg_pages(). |
360 | */ |
361 | static int bprm_mm_init(struct linux_binprm *bprm) |
362 | { |
363 | int err; |
364 | struct mm_struct *mm = NULL; |
365 | |
366 | bprm->mm = mm = mm_alloc(); |
367 | err = -ENOMEM; |
368 | if (!mm) |
369 | goto err; |
370 | |
371 | err = init_new_context(current, mm); |
372 | if (err) |
373 | goto err; |
374 | |
375 | err = __bprm_mm_init(bprm); |
376 | if (err) |
377 | goto err; |
378 | |
379 | return 0; |
380 | |
381 | err: |
382 | if (mm) { |
383 | bprm->mm = NULL; |
384 | mmdrop(mm); |
385 | } |
386 | |
387 | return err; |
388 | } |
389 | |
390 | struct user_arg_ptr { |
391 | #ifdef CONFIG_COMPAT |
392 | bool is_compat; |
393 | #endif |
394 | union { |
395 | const char __user *const __user *native; |
396 | #ifdef CONFIG_COMPAT |
397 | const compat_uptr_t __user *compat; |
398 | #endif |
399 | } ptr; |
400 | }; |
401 | |
402 | static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr) |
403 | { |
404 | const char __user *native; |
405 | |
406 | #ifdef CONFIG_COMPAT |
407 | if (unlikely(argv.is_compat)) { |
408 | compat_uptr_t compat; |
409 | |
410 | if (get_user(compat, argv.ptr.compat + nr)) |
411 | return ERR_PTR(-EFAULT); |
412 | |
413 | return compat_ptr(compat); |
414 | } |
415 | #endif |
416 | |
417 | if (get_user(native, argv.ptr.native + nr)) |
418 | return ERR_PTR(-EFAULT); |
419 | |
420 | return native; |
421 | } |
422 | |
423 | /* |
424 | * count() counts the number of strings in array ARGV. |
425 | */ |
426 | static int count(struct user_arg_ptr argv, int max) |
427 | { |
428 | int i = 0; |
429 | |
430 | if (argv.ptr.native != NULL) { |
431 | for (;;) { |
432 | const char __user *p = get_user_arg_ptr(argv, i); |
433 | |
434 | if (!p) |
435 | break; |
436 | |
437 | if (IS_ERR(p)) |
438 | return -EFAULT; |
439 | |
440 | if (i >= max) |
441 | return -E2BIG; |
442 | ++i; |
443 | |
444 | if (fatal_signal_pending(current)) |
445 | return -ERESTARTNOHAND; |
446 | cond_resched(); |
447 | } |
448 | } |
449 | return i; |
450 | } |
451 | |
452 | /* |
453 | * 'copy_strings()' copies argument/environment strings from the old |
454 | * processes's memory to the new process's stack. The call to get_user_pages() |
455 | * ensures the destination page is created and not swapped out. |
456 | */ |
457 | static int copy_strings(int argc, struct user_arg_ptr argv, |
458 | struct linux_binprm *bprm) |
459 | { |
460 | struct page *kmapped_page = NULL; |
461 | char *kaddr = NULL; |
462 | unsigned long kpos = 0; |
463 | int ret; |
464 | |
465 | while (argc-- > 0) { |
466 | const char __user *str; |
467 | int len; |
468 | unsigned long pos; |
469 | |
470 | ret = -EFAULT; |
471 | str = get_user_arg_ptr(argv, argc); |
472 | if (IS_ERR(str)) |
473 | goto out; |
474 | |
475 | len = strnlen_user(str, MAX_ARG_STRLEN); |
476 | if (!len) |
477 | goto out; |
478 | |
479 | ret = -E2BIG; |
480 | if (!valid_arg_len(bprm, len)) |
481 | goto out; |
482 | |
483 | /* We're going to work our way backwords. */ |
484 | pos = bprm->p; |
485 | str += len; |
486 | bprm->p -= len; |
487 | |
488 | while (len > 0) { |
489 | int offset, bytes_to_copy; |
490 | |
491 | if (fatal_signal_pending(current)) { |
492 | ret = -ERESTARTNOHAND; |
493 | goto out; |
494 | } |
495 | cond_resched(); |
496 | |
497 | offset = pos % PAGE_SIZE; |
498 | if (offset == 0) |
499 | offset = PAGE_SIZE; |
500 | |
501 | bytes_to_copy = offset; |
502 | if (bytes_to_copy > len) |
503 | bytes_to_copy = len; |
504 | |
505 | offset -= bytes_to_copy; |
506 | pos -= bytes_to_copy; |
507 | str -= bytes_to_copy; |
508 | len -= bytes_to_copy; |
509 | |
510 | if (!kmapped_page || kpos != (pos & PAGE_MASK)) { |
511 | struct page *page; |
512 | |
513 | page = get_arg_page(bprm, pos, 1); |
514 | if (!page) { |
515 | ret = -E2BIG; |
516 | goto out; |
517 | } |
518 | |
519 | if (kmapped_page) { |
520 | flush_kernel_dcache_page(kmapped_page); |
521 | kunmap(kmapped_page); |
522 | put_arg_page(kmapped_page); |
523 | } |
524 | kmapped_page = page; |
525 | kaddr = kmap(kmapped_page); |
526 | kpos = pos & PAGE_MASK; |
527 | flush_arg_page(bprm, kpos, kmapped_page); |
528 | } |
529 | if (copy_from_user(kaddr+offset, str, bytes_to_copy)) { |
530 | ret = -EFAULT; |
531 | goto out; |
532 | } |
533 | } |
534 | } |
535 | ret = 0; |
536 | out: |
537 | if (kmapped_page) { |
538 | flush_kernel_dcache_page(kmapped_page); |
539 | kunmap(kmapped_page); |
540 | put_arg_page(kmapped_page); |
541 | } |
542 | return ret; |
543 | } |
544 | |
545 | /* |
546 | * Like copy_strings, but get argv and its values from kernel memory. |
547 | */ |
548 | int copy_strings_kernel(int argc, const char *const *__argv, |
549 | struct linux_binprm *bprm) |
550 | { |
551 | int r; |
552 | mm_segment_t oldfs = get_fs(); |
553 | struct user_arg_ptr argv = { |
554 | .ptr.native = (const char __user *const __user *)__argv, |
555 | }; |
556 | |
557 | set_fs(KERNEL_DS); |
558 | r = copy_strings(argc, argv, bprm); |
559 | set_fs(oldfs); |
560 | |
561 | return r; |
562 | } |
563 | EXPORT_SYMBOL(copy_strings_kernel); |
564 | |
565 | #ifdef CONFIG_MMU |
566 | |
567 | /* |
568 | * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once |
569 | * the binfmt code determines where the new stack should reside, we shift it to |
570 | * its final location. The process proceeds as follows: |
571 | * |
572 | * 1) Use shift to calculate the new vma endpoints. |
573 | * 2) Extend vma to cover both the old and new ranges. This ensures the |
574 | * arguments passed to subsequent functions are consistent. |
575 | * 3) Move vma's page tables to the new range. |
576 | * 4) Free up any cleared pgd range. |
577 | * 5) Shrink the vma to cover only the new range. |
578 | */ |
579 | static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift) |
580 | { |
581 | struct mm_struct *mm = vma->vm_mm; |
582 | unsigned long old_start = vma->vm_start; |
583 | unsigned long old_end = vma->vm_end; |
584 | unsigned long length = old_end - old_start; |
585 | unsigned long new_start = old_start - shift; |
586 | unsigned long new_end = old_end - shift; |
587 | struct mmu_gather tlb; |
588 | |
589 | BUG_ON(new_start > new_end); |
590 | |
591 | /* |
592 | * ensure there are no vmas between where we want to go |
593 | * and where we are |
594 | */ |
595 | if (vma != find_vma(mm, new_start)) |
596 | return -EFAULT; |
597 | |
598 | /* |
599 | * cover the whole range: [new_start, old_end) |
600 | */ |
601 | if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL)) |
602 | return -ENOMEM; |
603 | |
604 | /* |
605 | * move the page tables downwards, on failure we rely on |
606 | * process cleanup to remove whatever mess we made. |
607 | */ |
608 | if (length != move_page_tables(vma, old_start, |
609 | vma, new_start, length, false)) |
610 | return -ENOMEM; |
611 | |
612 | lru_add_drain(); |
613 | tlb_gather_mmu(&tlb, mm, old_start, old_end); |
614 | if (new_end > old_start) { |
615 | /* |
616 | * when the old and new regions overlap clear from new_end. |
617 | */ |
618 | free_pgd_range(&tlb, new_end, old_end, new_end, |
619 | vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING); |
620 | } else { |
621 | /* |
622 | * otherwise, clean from old_start; this is done to not touch |
623 | * the address space in [new_end, old_start) some architectures |
624 | * have constraints on va-space that make this illegal (IA64) - |
625 | * for the others its just a little faster. |
626 | */ |
627 | free_pgd_range(&tlb, old_start, old_end, new_end, |
628 | vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING); |
629 | } |
630 | tlb_finish_mmu(&tlb, old_start, old_end); |
631 | |
632 | /* |
633 | * Shrink the vma to just the new range. Always succeeds. |
634 | */ |
635 | vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL); |
636 | |
637 | return 0; |
638 | } |
639 | |
640 | /* |
641 | * Finalizes the stack vm_area_struct. The flags and permissions are updated, |
642 | * the stack is optionally relocated, and some extra space is added. |
643 | */ |
644 | int setup_arg_pages(struct linux_binprm *bprm, |
645 | unsigned long stack_top, |
646 | int executable_stack) |
647 | { |
648 | unsigned long ret; |
649 | unsigned long stack_shift; |
650 | struct mm_struct *mm = current->mm; |
651 | struct vm_area_struct *vma = bprm->vma; |
652 | struct vm_area_struct *prev = NULL; |
653 | unsigned long vm_flags; |
654 | unsigned long stack_base; |
655 | unsigned long stack_size; |
656 | unsigned long stack_expand; |
657 | unsigned long rlim_stack; |
658 | |
659 | #ifdef CONFIG_STACK_GROWSUP |
660 | /* Limit stack size */ |
661 | stack_base = rlimit_max(RLIMIT_STACK); |
662 | if (stack_base > STACK_SIZE_MAX) |
663 | stack_base = STACK_SIZE_MAX; |
664 | |
665 | /* Make sure we didn't let the argument array grow too large. */ |
666 | if (vma->vm_end - vma->vm_start > stack_base) |
667 | return -ENOMEM; |
668 | |
669 | stack_base = PAGE_ALIGN(stack_top - stack_base); |
670 | |
671 | stack_shift = vma->vm_start - stack_base; |
672 | mm->arg_start = bprm->p - stack_shift; |
673 | bprm->p = vma->vm_end - stack_shift; |
674 | #else |
675 | stack_top = arch_align_stack(stack_top); |
676 | stack_top = PAGE_ALIGN(stack_top); |
677 | |
678 | if (unlikely(stack_top < mmap_min_addr) || |
679 | unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr)) |
680 | return -ENOMEM; |
681 | |
682 | stack_shift = vma->vm_end - stack_top; |
683 | |
684 | bprm->p -= stack_shift; |
685 | mm->arg_start = bprm->p; |
686 | #endif |
687 | |
688 | if (bprm->loader) |
689 | bprm->loader -= stack_shift; |
690 | bprm->exec -= stack_shift; |
691 | |
692 | down_write(&mm->mmap_sem); |
693 | vm_flags = VM_STACK_FLAGS; |
694 | |
695 | /* |
696 | * Adjust stack execute permissions; explicitly enable for |
697 | * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone |
698 | * (arch default) otherwise. |
699 | */ |
700 | if (unlikely(executable_stack == EXSTACK_ENABLE_X)) |
701 | vm_flags |= VM_EXEC; |
702 | else if (executable_stack == EXSTACK_DISABLE_X) |
703 | vm_flags &= ~VM_EXEC; |
704 | vm_flags |= mm->def_flags; |
705 | vm_flags |= VM_STACK_INCOMPLETE_SETUP; |
706 | |
707 | ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end, |
708 | vm_flags); |
709 | if (ret) |
710 | goto out_unlock; |
711 | BUG_ON(prev != vma); |
712 | |
713 | /* Move stack pages down in memory. */ |
714 | if (stack_shift) { |
715 | ret = shift_arg_pages(vma, stack_shift); |
716 | if (ret) |
717 | goto out_unlock; |
718 | } |
719 | |
720 | /* mprotect_fixup is overkill to remove the temporary stack flags */ |
721 | vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP; |
722 | |
723 | stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */ |
724 | stack_size = vma->vm_end - vma->vm_start; |
725 | /* |
726 | * Align this down to a page boundary as expand_stack |
727 | * will align it up. |
728 | */ |
729 | rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK; |
730 | #ifdef CONFIG_STACK_GROWSUP |
731 | if (stack_size + stack_expand > rlim_stack) |
732 | stack_base = vma->vm_start + rlim_stack; |
733 | else |
734 | stack_base = vma->vm_end + stack_expand; |
735 | #else |
736 | if (stack_size + stack_expand > rlim_stack) |
737 | stack_base = vma->vm_end - rlim_stack; |
738 | else |
739 | stack_base = vma->vm_start - stack_expand; |
740 | #endif |
741 | current->mm->start_stack = bprm->p; |
742 | ret = expand_stack(vma, stack_base); |
743 | if (ret) |
744 | ret = -EFAULT; |
745 | |
746 | out_unlock: |
747 | up_write(&mm->mmap_sem); |
748 | return ret; |
749 | } |
750 | EXPORT_SYMBOL(setup_arg_pages); |
751 | |
752 | #endif /* CONFIG_MMU */ |
753 | |
754 | static struct file *do_open_exec(struct filename *name) |
755 | { |
756 | struct file *file; |
757 | int err; |
758 | static const struct open_flags open_exec_flags = { |
759 | .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, |
760 | .acc_mode = MAY_EXEC | MAY_OPEN, |
761 | .intent = LOOKUP_OPEN, |
762 | .lookup_flags = LOOKUP_FOLLOW, |
763 | }; |
764 | |
765 | file = do_filp_open(AT_FDCWD, name, &open_exec_flags); |
766 | if (IS_ERR(file)) |
767 | goto out; |
768 | |
769 | err = -EACCES; |
770 | if (!S_ISREG(file_inode(file)->i_mode)) |
771 | goto exit; |
772 | |
773 | if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) |
774 | goto exit; |
775 | |
776 | fsnotify_open(file); |
777 | |
778 | err = deny_write_access(file); |
779 | if (err) |
780 | goto exit; |
781 | |
782 | out: |
783 | return file; |
784 | |
785 | exit: |
786 | fput(file); |
787 | return ERR_PTR(err); |
788 | } |
789 | |
790 | struct file *open_exec(const char *name) |
791 | { |
792 | struct filename tmp = { .name = name }; |
793 | return do_open_exec(&tmp); |
794 | } |
795 | EXPORT_SYMBOL(open_exec); |
796 | |
797 | int kernel_read(struct file *file, loff_t offset, |
798 | char *addr, unsigned long count) |
799 | { |
800 | mm_segment_t old_fs; |
801 | loff_t pos = offset; |
802 | int result; |
803 | |
804 | old_fs = get_fs(); |
805 | set_fs(get_ds()); |
806 | /* The cast to a user pointer is valid due to the set_fs() */ |
807 | result = vfs_read(file, (void __user *)addr, count, &pos); |
808 | set_fs(old_fs); |
809 | return result; |
810 | } |
811 | |
812 | EXPORT_SYMBOL(kernel_read); |
813 | |
814 | ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len) |
815 | { |
816 | ssize_t res = vfs_read(file, (void __user *)addr, len, &pos); |
817 | if (res > 0) |
818 | flush_icache_range(addr, addr + len); |
819 | return res; |
820 | } |
821 | EXPORT_SYMBOL(read_code); |
822 | |
823 | static int exec_mmap(struct mm_struct *mm) |
824 | { |
825 | struct task_struct *tsk; |
826 | struct mm_struct *old_mm, *active_mm; |
827 | |
828 | /* Notify parent that we're no longer interested in the old VM */ |
829 | tsk = current; |
830 | old_mm = current->mm; |
831 | mm_release(tsk, old_mm); |
832 | |
833 | if (old_mm) { |
834 | sync_mm_rss(old_mm); |
835 | /* |
836 | * Make sure that if there is a core dump in progress |
837 | * for the old mm, we get out and die instead of going |
838 | * through with the exec. We must hold mmap_sem around |
839 | * checking core_state and changing tsk->mm. |
840 | */ |
841 | down_read(&old_mm->mmap_sem); |
842 | if (unlikely(old_mm->core_state)) { |
843 | up_read(&old_mm->mmap_sem); |
844 | return -EINTR; |
845 | } |
846 | } |
847 | task_lock(tsk); |
848 | active_mm = tsk->active_mm; |
849 | tsk->mm = mm; |
850 | tsk->active_mm = mm; |
851 | activate_mm(active_mm, mm); |
852 | tsk->mm->vmacache_seqnum = 0; |
853 | vmacache_flush(tsk); |
854 | task_unlock(tsk); |
855 | if (old_mm) { |
856 | up_read(&old_mm->mmap_sem); |
857 | BUG_ON(active_mm != old_mm); |
858 | setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm); |
859 | mm_update_next_owner(old_mm); |
860 | mmput(old_mm); |
861 | return 0; |
862 | } |
863 | mmdrop(active_mm); |
864 | return 0; |
865 | } |
866 | |
867 | /* |
868 | * This function makes sure the current process has its own signal table, |
869 | * so that flush_signal_handlers can later reset the handlers without |
870 | * disturbing other processes. (Other processes might share the signal |
871 | * table via the CLONE_SIGHAND option to clone().) |
872 | */ |
873 | static int de_thread(struct task_struct *tsk) |
874 | { |
875 | struct signal_struct *sig = tsk->signal; |
876 | struct sighand_struct *oldsighand = tsk->sighand; |
877 | spinlock_t *lock = &oldsighand->siglock; |
878 | |
879 | if (thread_group_empty(tsk)) |
880 | goto no_thread_group; |
881 | |
882 | /* |
883 | * Kill all other threads in the thread group. |
884 | */ |
885 | spin_lock_irq(lock); |
886 | if (signal_group_exit(sig)) { |
887 | /* |
888 | * Another group action in progress, just |
889 | * return so that the signal is processed. |
890 | */ |
891 | spin_unlock_irq(lock); |
892 | return -EAGAIN; |
893 | } |
894 | |
895 | sig->group_exit_task = tsk; |
896 | sig->notify_count = zap_other_threads(tsk); |
897 | if (!thread_group_leader(tsk)) |
898 | sig->notify_count--; |
899 | |
900 | while (sig->notify_count) { |
901 | __set_current_state(TASK_KILLABLE); |
902 | spin_unlock_irq(lock); |
903 | schedule(); |
904 | if (unlikely(__fatal_signal_pending(tsk))) |
905 | goto killed; |
906 | spin_lock_irq(lock); |
907 | } |
908 | spin_unlock_irq(lock); |
909 | |
910 | /* |
911 | * At this point all other threads have exited, all we have to |
912 | * do is to wait for the thread group leader to become inactive, |
913 | * and to assume its PID: |
914 | */ |
915 | if (!thread_group_leader(tsk)) { |
916 | struct task_struct *leader = tsk->group_leader; |
917 | |
918 | sig->notify_count = -1; /* for exit_notify() */ |
919 | for (;;) { |
920 | threadgroup_change_begin(tsk); |
921 | write_lock_irq(&tasklist_lock); |
922 | if (likely(leader->exit_state)) |
923 | break; |
924 | __set_current_state(TASK_KILLABLE); |
925 | write_unlock_irq(&tasklist_lock); |
926 | threadgroup_change_end(tsk); |
927 | schedule(); |
928 | if (unlikely(__fatal_signal_pending(tsk))) |
929 | goto killed; |
930 | } |
931 | |
932 | /* |
933 | * The only record we have of the real-time age of a |
934 | * process, regardless of execs it's done, is start_time. |
935 | * All the past CPU time is accumulated in signal_struct |
936 | * from sister threads now dead. But in this non-leader |
937 | * exec, nothing survives from the original leader thread, |
938 | * whose birth marks the true age of this process now. |
939 | * When we take on its identity by switching to its PID, we |
940 | * also take its birthdate (always earlier than our own). |
941 | */ |
942 | tsk->start_time = leader->start_time; |
943 | tsk->real_start_time = leader->real_start_time; |
944 | |
945 | BUG_ON(!same_thread_group(leader, tsk)); |
946 | BUG_ON(has_group_leader_pid(tsk)); |
947 | /* |
948 | * An exec() starts a new thread group with the |
949 | * TGID of the previous thread group. Rehash the |
950 | * two threads with a switched PID, and release |
951 | * the former thread group leader: |
952 | */ |
953 | |
954 | /* Become a process group leader with the old leader's pid. |
955 | * The old leader becomes a thread of the this thread group. |
956 | * Note: The old leader also uses this pid until release_task |
957 | * is called. Odd but simple and correct. |
958 | */ |
959 | tsk->pid = leader->pid; |
960 | change_pid(tsk, PIDTYPE_PID, task_pid(leader)); |
961 | transfer_pid(leader, tsk, PIDTYPE_PGID); |
962 | transfer_pid(leader, tsk, PIDTYPE_SID); |
963 | |
964 | list_replace_rcu(&leader->tasks, &tsk->tasks); |
965 | list_replace_init(&leader->sibling, &tsk->sibling); |
966 | |
967 | tsk->group_leader = tsk; |
968 | leader->group_leader = tsk; |
969 | |
970 | tsk->exit_signal = SIGCHLD; |
971 | leader->exit_signal = -1; |
972 | |
973 | BUG_ON(leader->exit_state != EXIT_ZOMBIE); |
974 | leader->exit_state = EXIT_DEAD; |
975 | |
976 | /* |
977 | * We are going to release_task()->ptrace_unlink() silently, |
978 | * the tracer can sleep in do_wait(). EXIT_DEAD guarantees |
979 | * the tracer wont't block again waiting for this thread. |
980 | */ |
981 | if (unlikely(leader->ptrace)) |
982 | __wake_up_parent(leader, leader->parent); |
983 | write_unlock_irq(&tasklist_lock); |
984 | threadgroup_change_end(tsk); |
985 | |
986 | release_task(leader); |
987 | } |
988 | |
989 | sig->group_exit_task = NULL; |
990 | sig->notify_count = 0; |
991 | |
992 | no_thread_group: |
993 | /* we have changed execution domain */ |
994 | tsk->exit_signal = SIGCHLD; |
995 | |
996 | exit_itimers(sig); |
997 | flush_itimer_signals(); |
998 | |
999 | if (atomic_read(&oldsighand->count) != 1) { |
1000 | struct sighand_struct *newsighand; |
1001 | /* |
1002 | * This ->sighand is shared with the CLONE_SIGHAND |
1003 | * but not CLONE_THREAD task, switch to the new one. |
1004 | */ |
1005 | newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); |
1006 | if (!newsighand) |
1007 | return -ENOMEM; |
1008 | |
1009 | atomic_set(&newsighand->count, 1); |
1010 | memcpy(newsighand->action, oldsighand->action, |
1011 | sizeof(newsighand->action)); |
1012 | |
1013 | write_lock_irq(&tasklist_lock); |
1014 | spin_lock(&oldsighand->siglock); |
1015 | rcu_assign_pointer(tsk->sighand, newsighand); |
1016 | spin_unlock(&oldsighand->siglock); |
1017 | write_unlock_irq(&tasklist_lock); |
1018 | |
1019 | __cleanup_sighand(oldsighand); |
1020 | } |
1021 | |
1022 | BUG_ON(!thread_group_leader(tsk)); |
1023 | return 0; |
1024 | |
1025 | killed: |
1026 | /* protects against exit_notify() and __exit_signal() */ |
1027 | read_lock(&tasklist_lock); |
1028 | sig->group_exit_task = NULL; |
1029 | sig->notify_count = 0; |
1030 | read_unlock(&tasklist_lock); |
1031 | return -EAGAIN; |
1032 | } |
1033 | |
1034 | char *get_task_comm(char *buf, struct task_struct *tsk) |
1035 | { |
1036 | /* buf must be at least sizeof(tsk->comm) in size */ |
1037 | task_lock(tsk); |
1038 | strncpy(buf, tsk->comm, sizeof(tsk->comm)); |
1039 | task_unlock(tsk); |
1040 | return buf; |
1041 | } |
1042 | EXPORT_SYMBOL_GPL(get_task_comm); |
1043 | |
1044 | /* |
1045 | * These functions flushes out all traces of the currently running executable |
1046 | * so that a new one can be started |
1047 | */ |
1048 | |
1049 | void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec) |
1050 | { |
1051 | task_lock(tsk); |
1052 | trace_task_rename(tsk, buf); |
1053 | strlcpy(tsk->comm, buf, sizeof(tsk->comm)); |
1054 | task_unlock(tsk); |
1055 | perf_event_comm(tsk, exec); |
1056 | } |
1057 | |
1058 | int flush_old_exec(struct linux_binprm * bprm) |
1059 | { |
1060 | int retval; |
1061 | |
1062 | /* |
1063 | * Make sure we have a private signal table and that |
1064 | * we are unassociated from the previous thread group. |
1065 | */ |
1066 | retval = de_thread(current); |
1067 | if (retval) |
1068 | goto out; |
1069 | |
1070 | set_mm_exe_file(bprm->mm, bprm->file); |
1071 | /* |
1072 | * Release all of the old mmap stuff |
1073 | */ |
1074 | acct_arg_size(bprm, 0); |
1075 | retval = exec_mmap(bprm->mm); |
1076 | if (retval) |
1077 | goto out; |
1078 | |
1079 | bprm->mm = NULL; /* We're using it now */ |
1080 | |
1081 | set_fs(USER_DS); |
1082 | current->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | |
1083 | PF_NOFREEZE | PF_NO_SETAFFINITY); |
1084 | flush_thread(); |
1085 | current->personality &= ~bprm->per_clear; |
1086 | |
1087 | return 0; |
1088 | |
1089 | out: |
1090 | return retval; |
1091 | } |
1092 | EXPORT_SYMBOL(flush_old_exec); |
1093 | |
1094 | void would_dump(struct linux_binprm *bprm, struct file *file) |
1095 | { |
1096 | if (inode_permission(file_inode(file), MAY_READ) < 0) |
1097 | bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP; |
1098 | } |
1099 | EXPORT_SYMBOL(would_dump); |
1100 | |
1101 | void setup_new_exec(struct linux_binprm * bprm) |
1102 | { |
1103 | arch_pick_mmap_layout(current->mm); |
1104 | |
1105 | /* This is the point of no return */ |
1106 | current->sas_ss_sp = current->sas_ss_size = 0; |
1107 | |
1108 | if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid())) |
1109 | set_dumpable(current->mm, SUID_DUMP_USER); |
1110 | else |
1111 | set_dumpable(current->mm, suid_dumpable); |
1112 | |
1113 | perf_event_exec(); |
1114 | __set_task_comm(current, kbasename(bprm->filename), true); |
1115 | |
1116 | /* Set the new mm task size. We have to do that late because it may |
1117 | * depend on TIF_32BIT which is only updated in flush_thread() on |
1118 | * some architectures like powerpc |
1119 | */ |
1120 | current->mm->task_size = TASK_SIZE; |
1121 | |
1122 | /* install the new credentials */ |
1123 | if (!uid_eq(bprm->cred->uid, current_euid()) || |
1124 | !gid_eq(bprm->cred->gid, current_egid())) { |
1125 | current->pdeath_signal = 0; |
1126 | } else { |
1127 | would_dump(bprm, bprm->file); |
1128 | if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) |
1129 | set_dumpable(current->mm, suid_dumpable); |
1130 | } |
1131 | |
1132 | /* An exec changes our domain. We are no longer part of the thread |
1133 | group */ |
1134 | current->self_exec_id++; |
1135 | flush_signal_handlers(current, 0); |
1136 | do_close_on_exec(current->files); |
1137 | } |
1138 | EXPORT_SYMBOL(setup_new_exec); |
1139 | |
1140 | /* |
1141 | * Prepare credentials and lock ->cred_guard_mutex. |
1142 | * install_exec_creds() commits the new creds and drops the lock. |
1143 | * Or, if exec fails before, free_bprm() should release ->cred and |
1144 | * and unlock. |
1145 | */ |
1146 | int prepare_bprm_creds(struct linux_binprm *bprm) |
1147 | { |
1148 | if (mutex_lock_interruptible(¤t->signal->cred_guard_mutex)) |
1149 | return -ERESTARTNOINTR; |
1150 | |
1151 | bprm->cred = prepare_exec_creds(); |
1152 | if (likely(bprm->cred)) |
1153 | return 0; |
1154 | |
1155 | mutex_unlock(¤t->signal->cred_guard_mutex); |
1156 | return -ENOMEM; |
1157 | } |
1158 | |
1159 | static void free_bprm(struct linux_binprm *bprm) |
1160 | { |
1161 | free_arg_pages(bprm); |
1162 | if (bprm->cred) { |
1163 | mutex_unlock(¤t->signal->cred_guard_mutex); |
1164 | abort_creds(bprm->cred); |
1165 | } |
1166 | if (bprm->file) { |
1167 | allow_write_access(bprm->file); |
1168 | fput(bprm->file); |
1169 | } |
1170 | /* If a binfmt changed the interp, free it. */ |
1171 | if (bprm->interp != bprm->filename) |
1172 | kfree(bprm->interp); |
1173 | kfree(bprm); |
1174 | } |
1175 | |
1176 | int bprm_change_interp(char *interp, struct linux_binprm *bprm) |
1177 | { |
1178 | /* If a binfmt changed the interp, free it first. */ |
1179 | if (bprm->interp != bprm->filename) |
1180 | kfree(bprm->interp); |
1181 | bprm->interp = kstrdup(interp, GFP_KERNEL); |
1182 | if (!bprm->interp) |
1183 | return -ENOMEM; |
1184 | return 0; |
1185 | } |
1186 | EXPORT_SYMBOL(bprm_change_interp); |
1187 | |
1188 | /* |
1189 | * install the new credentials for this executable |
1190 | */ |
1191 | void install_exec_creds(struct linux_binprm *bprm) |
1192 | { |
1193 | security_bprm_committing_creds(bprm); |
1194 | |
1195 | commit_creds(bprm->cred); |
1196 | bprm->cred = NULL; |
1197 | |
1198 | /* |
1199 | * Disable monitoring for regular users |
1200 | * when executing setuid binaries. Must |
1201 | * wait until new credentials are committed |
1202 | * by commit_creds() above |
1203 | */ |
1204 | if (get_dumpable(current->mm) != SUID_DUMP_USER) |
1205 | perf_event_exit_task(current); |
1206 | /* |
1207 | * cred_guard_mutex must be held at least to this point to prevent |
1208 | * ptrace_attach() from altering our determination of the task's |
1209 | * credentials; any time after this it may be unlocked. |
1210 | */ |
1211 | security_bprm_committed_creds(bprm); |
1212 | mutex_unlock(¤t->signal->cred_guard_mutex); |
1213 | } |
1214 | EXPORT_SYMBOL(install_exec_creds); |
1215 | |
1216 | /* |
1217 | * determine how safe it is to execute the proposed program |
1218 | * - the caller must hold ->cred_guard_mutex to protect against |
1219 | * PTRACE_ATTACH |
1220 | */ |
1221 | static void check_unsafe_exec(struct linux_binprm *bprm) |
1222 | { |
1223 | struct task_struct *p = current, *t; |
1224 | unsigned n_fs; |
1225 | |
1226 | if (p->ptrace) { |
1227 | if (p->ptrace & PT_PTRACE_CAP) |
1228 | bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP; |
1229 | else |
1230 | bprm->unsafe |= LSM_UNSAFE_PTRACE; |
1231 | } |
1232 | |
1233 | /* |
1234 | * This isn't strictly necessary, but it makes it harder for LSMs to |
1235 | * mess up. |
1236 | */ |
1237 | if (current->no_new_privs) |
1238 | bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS; |
1239 | |
1240 | t = p; |
1241 | n_fs = 1; |
1242 | spin_lock(&p->fs->lock); |
1243 | rcu_read_lock(); |
1244 | while_each_thread(p, t) { |
1245 | if (t->fs == p->fs) |
1246 | n_fs++; |
1247 | } |
1248 | rcu_read_unlock(); |
1249 | |
1250 | if (p->fs->users > n_fs) |
1251 | bprm->unsafe |= LSM_UNSAFE_SHARE; |
1252 | else |
1253 | p->fs->in_exec = 1; |
1254 | spin_unlock(&p->fs->lock); |
1255 | } |
1256 | |
1257 | /* |
1258 | * Fill the binprm structure from the inode. |
1259 | * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes |
1260 | * |
1261 | * This may be called multiple times for binary chains (scripts for example). |
1262 | */ |
1263 | int prepare_binprm(struct linux_binprm *bprm) |
1264 | { |
1265 | struct inode *inode = file_inode(bprm->file); |
1266 | umode_t mode = inode->i_mode; |
1267 | int retval; |
1268 | |
1269 | |
1270 | /* clear any previous set[ug]id data from a previous binary */ |
1271 | bprm->cred->euid = current_euid(); |
1272 | bprm->cred->egid = current_egid(); |
1273 | |
1274 | if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) && |
1275 | !current->no_new_privs && |
1276 | kuid_has_mapping(bprm->cred->user_ns, inode->i_uid) && |
1277 | kgid_has_mapping(bprm->cred->user_ns, inode->i_gid)) { |
1278 | /* Set-uid? */ |
1279 | if (mode & S_ISUID) { |
1280 | bprm->per_clear |= PER_CLEAR_ON_SETID; |
1281 | bprm->cred->euid = inode->i_uid; |
1282 | } |
1283 | |
1284 | /* Set-gid? */ |
1285 | /* |
1286 | * If setgid is set but no group execute bit then this |
1287 | * is a candidate for mandatory locking, not a setgid |
1288 | * executable. |
1289 | */ |
1290 | if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { |
1291 | bprm->per_clear |= PER_CLEAR_ON_SETID; |
1292 | bprm->cred->egid = inode->i_gid; |
1293 | } |
1294 | } |
1295 | |
1296 | /* fill in binprm security blob */ |
1297 | retval = security_bprm_set_creds(bprm); |
1298 | if (retval) |
1299 | return retval; |
1300 | bprm->cred_prepared = 1; |
1301 | |
1302 | memset(bprm->buf, 0, BINPRM_BUF_SIZE); |
1303 | return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE); |
1304 | } |
1305 | |
1306 | EXPORT_SYMBOL(prepare_binprm); |
1307 | |
1308 | /* |
1309 | * Arguments are '\0' separated strings found at the location bprm->p |
1310 | * points to; chop off the first by relocating brpm->p to right after |
1311 | * the first '\0' encountered. |
1312 | */ |
1313 | int remove_arg_zero(struct linux_binprm *bprm) |
1314 | { |
1315 | int ret = 0; |
1316 | unsigned long offset; |
1317 | char *kaddr; |
1318 | struct page *page; |
1319 | |
1320 | if (!bprm->argc) |
1321 | return 0; |
1322 | |
1323 | do { |
1324 | offset = bprm->p & ~PAGE_MASK; |
1325 | page = get_arg_page(bprm, bprm->p, 0); |
1326 | if (!page) { |
1327 | ret = -EFAULT; |
1328 | goto out; |
1329 | } |
1330 | kaddr = kmap_atomic(page); |
1331 | |
1332 | for (; offset < PAGE_SIZE && kaddr[offset]; |
1333 | offset++, bprm->p++) |
1334 | ; |
1335 | |
1336 | kunmap_atomic(kaddr); |
1337 | put_arg_page(page); |
1338 | |
1339 | if (offset == PAGE_SIZE) |
1340 | free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1); |
1341 | } while (offset == PAGE_SIZE); |
1342 | |
1343 | bprm->p++; |
1344 | bprm->argc--; |
1345 | ret = 0; |
1346 | |
1347 | out: |
1348 | return ret; |
1349 | } |
1350 | EXPORT_SYMBOL(remove_arg_zero); |
1351 | |
1352 | #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e)) |
1353 | /* |
1354 | * cycle the list of binary formats handler, until one recognizes the image |
1355 | */ |
1356 | int search_binary_handler(struct linux_binprm *bprm) |
1357 | { |
1358 | bool need_retry = IS_ENABLED(CONFIG_MODULES); |
1359 | struct linux_binfmt *fmt; |
1360 | int retval; |
1361 | |
1362 | /* This allows 4 levels of binfmt rewrites before failing hard. */ |
1363 | if (bprm->recursion_depth > 5) |
1364 | return -ELOOP; |
1365 | |
1366 | retval = security_bprm_check(bprm); |
1367 | if (retval) |
1368 | return retval; |
1369 | |
1370 | retval = -ENOENT; |
1371 | retry: |
1372 | read_lock(&binfmt_lock); |
1373 | list_for_each_entry(fmt, &formats, lh) { |
1374 | if (!try_module_get(fmt->module)) |
1375 | continue; |
1376 | read_unlock(&binfmt_lock); |
1377 | bprm->recursion_depth++; |
1378 | retval = fmt->load_binary(bprm); |
1379 | bprm->recursion_depth--; |
1380 | if (retval >= 0 || retval != -ENOEXEC || |
1381 | bprm->mm == NULL || bprm->file == NULL) { |
1382 | put_binfmt(fmt); |
1383 | return retval; |
1384 | } |
1385 | read_lock(&binfmt_lock); |
1386 | put_binfmt(fmt); |
1387 | } |
1388 | read_unlock(&binfmt_lock); |
1389 | |
1390 | if (need_retry && retval == -ENOEXEC) { |
1391 | if (printable(bprm->buf[0]) && printable(bprm->buf[1]) && |
1392 | printable(bprm->buf[2]) && printable(bprm->buf[3])) |
1393 | return retval; |
1394 | if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0) |
1395 | return retval; |
1396 | need_retry = false; |
1397 | goto retry; |
1398 | } |
1399 | |
1400 | return retval; |
1401 | } |
1402 | EXPORT_SYMBOL(search_binary_handler); |
1403 | |
1404 | static int exec_binprm(struct linux_binprm *bprm) |
1405 | { |
1406 | pid_t old_pid, old_vpid; |
1407 | int ret; |
1408 | |
1409 | /* Need to fetch pid before load_binary changes it */ |
1410 | old_pid = current->pid; |
1411 | rcu_read_lock(); |
1412 | old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent)); |
1413 | rcu_read_unlock(); |
1414 | |
1415 | ret = search_binary_handler(bprm); |
1416 | if (ret >= 0) { |
1417 | audit_bprm(bprm); |
1418 | trace_sched_process_exec(current, old_pid, bprm); |
1419 | ptrace_event(PTRACE_EVENT_EXEC, old_vpid); |
1420 | proc_exec_connector(current); |
1421 | } |
1422 | |
1423 | return ret; |
1424 | } |
1425 | |
1426 | /* |
1427 | * sys_execve() executes a new program. |
1428 | */ |
1429 | static int do_execve_common(struct filename *filename, |
1430 | struct user_arg_ptr argv, |
1431 | struct user_arg_ptr envp) |
1432 | { |
1433 | struct linux_binprm *bprm; |
1434 | struct file *file; |
1435 | struct files_struct *displaced; |
1436 | int retval; |
1437 | |
1438 | if (IS_ERR(filename)) |
1439 | return PTR_ERR(filename); |
1440 | |
1441 | /* |
1442 | * We move the actual failure in case of RLIMIT_NPROC excess from |
1443 | * set*uid() to execve() because too many poorly written programs |
1444 | * don't check setuid() return code. Here we additionally recheck |
1445 | * whether NPROC limit is still exceeded. |
1446 | */ |
1447 | if ((current->flags & PF_NPROC_EXCEEDED) && |
1448 | atomic_read(¤t_user()->processes) > rlimit(RLIMIT_NPROC)) { |
1449 | retval = -EAGAIN; |
1450 | goto out_ret; |
1451 | } |
1452 | |
1453 | /* We're below the limit (still or again), so we don't want to make |
1454 | * further execve() calls fail. */ |
1455 | current->flags &= ~PF_NPROC_EXCEEDED; |
1456 | |
1457 | retval = unshare_files(&displaced); |
1458 | if (retval) |
1459 | goto out_ret; |
1460 | |
1461 | retval = -ENOMEM; |
1462 | bprm = kzalloc(sizeof(*bprm), GFP_KERNEL); |
1463 | if (!bprm) |
1464 | goto out_files; |
1465 | |
1466 | retval = prepare_bprm_creds(bprm); |
1467 | if (retval) |
1468 | goto out_free; |
1469 | |
1470 | check_unsafe_exec(bprm); |
1471 | current->in_execve = 1; |
1472 | |
1473 | file = do_open_exec(filename); |
1474 | retval = PTR_ERR(file); |
1475 | if (IS_ERR(file)) |
1476 | goto out_unmark; |
1477 | |
1478 | sched_exec(); |
1479 | |
1480 | bprm->file = file; |
1481 | bprm->filename = bprm->interp = filename->name; |
1482 | |
1483 | retval = bprm_mm_init(bprm); |
1484 | if (retval) |
1485 | goto out_unmark; |
1486 | |
1487 | bprm->argc = count(argv, MAX_ARG_STRINGS); |
1488 | if ((retval = bprm->argc) < 0) |
1489 | goto out; |
1490 | |
1491 | bprm->envc = count(envp, MAX_ARG_STRINGS); |
1492 | if ((retval = bprm->envc) < 0) |
1493 | goto out; |
1494 | |
1495 | retval = prepare_binprm(bprm); |
1496 | if (retval < 0) |
1497 | goto out; |
1498 | |
1499 | retval = copy_strings_kernel(1, &bprm->filename, bprm); |
1500 | if (retval < 0) |
1501 | goto out; |
1502 | |
1503 | bprm->exec = bprm->p; |
1504 | retval = copy_strings(bprm->envc, envp, bprm); |
1505 | if (retval < 0) |
1506 | goto out; |
1507 | |
1508 | retval = copy_strings(bprm->argc, argv, bprm); |
1509 | if (retval < 0) |
1510 | goto out; |
1511 | |
1512 | retval = exec_binprm(bprm); |
1513 | if (retval < 0) |
1514 | goto out; |
1515 | |
1516 | /* execve succeeded */ |
1517 | current->fs->in_exec = 0; |
1518 | current->in_execve = 0; |
1519 | acct_update_integrals(current); |
1520 | task_numa_free(current); |
1521 | free_bprm(bprm); |
1522 | putname(filename); |
1523 | if (displaced) |
1524 | put_files_struct(displaced); |
1525 | return retval; |
1526 | |
1527 | out: |
1528 | if (bprm->mm) { |
1529 | acct_arg_size(bprm, 0); |
1530 | mmput(bprm->mm); |
1531 | } |
1532 | |
1533 | out_unmark: |
1534 | current->fs->in_exec = 0; |
1535 | current->in_execve = 0; |
1536 | |
1537 | out_free: |
1538 | free_bprm(bprm); |
1539 | |
1540 | out_files: |
1541 | if (displaced) |
1542 | reset_files_struct(displaced); |
1543 | out_ret: |
1544 | putname(filename); |
1545 | return retval; |
1546 | } |
1547 | |
1548 | int do_execve(struct filename *filename, |
1549 | const char __user *const __user *__argv, |
1550 | const char __user *const __user *__envp) |
1551 | { |
1552 | struct user_arg_ptr argv = { .ptr.native = __argv }; |
1553 | struct user_arg_ptr envp = { .ptr.native = __envp }; |
1554 | return do_execve_common(filename, argv, envp); |
1555 | } |
1556 | |
1557 | #ifdef CONFIG_COMPAT |
1558 | static int compat_do_execve(struct filename *filename, |
1559 | const compat_uptr_t __user *__argv, |
1560 | const compat_uptr_t __user *__envp) |
1561 | { |
1562 | struct user_arg_ptr argv = { |
1563 | .is_compat = true, |
1564 | .ptr.compat = __argv, |
1565 | }; |
1566 | struct user_arg_ptr envp = { |
1567 | .is_compat = true, |
1568 | .ptr.compat = __envp, |
1569 | }; |
1570 | return do_execve_common(filename, argv, envp); |
1571 | } |
1572 | #endif |
1573 | |
1574 | void set_binfmt(struct linux_binfmt *new) |
1575 | { |
1576 | struct mm_struct *mm = current->mm; |
1577 | |
1578 | if (mm->binfmt) |
1579 | module_put(mm->binfmt->module); |
1580 | |
1581 | mm->binfmt = new; |
1582 | if (new) |
1583 | __module_get(new->module); |
1584 | } |
1585 | EXPORT_SYMBOL(set_binfmt); |
1586 | |
1587 | /* |
1588 | * set_dumpable stores three-value SUID_DUMP_* into mm->flags. |
1589 | */ |
1590 | void set_dumpable(struct mm_struct *mm, int value) |
1591 | { |
1592 | unsigned long old, new; |
1593 | |
1594 | if (WARN_ON((unsigned)value > SUID_DUMP_ROOT)) |
1595 | return; |
1596 | |
1597 | do { |
1598 | old = ACCESS_ONCE(mm->flags); |
1599 | new = (old & ~MMF_DUMPABLE_MASK) | value; |
1600 | } while (cmpxchg(&mm->flags, old, new) != old); |
1601 | } |
1602 | |
1603 | SYSCALL_DEFINE3(execve, |
1604 | const char __user *, filename, |
1605 | const char __user *const __user *, argv, |
1606 | const char __user *const __user *, envp) |
1607 | { |
1608 | return do_execve(getname(filename), argv, envp); |
1609 | } |
1610 | #ifdef CONFIG_COMPAT |
1611 | COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename, |
1612 | const compat_uptr_t __user *, argv, |
1613 | const compat_uptr_t __user *, envp) |
1614 | { |
1615 | return compat_do_execve(getname(filename), argv, envp); |
1616 | } |
1617 | #endif |
1618 |
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Tags:
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v2.6.34-rc5
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