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Source at commit b386be689295730688885552666ea40b2e639b14 created 11 years 11 months ago. By Maarten ter Huurne, Revert "MIPS: JZ4740: reset: Initialize hibernate wakeup counters." | |
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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/stat.h> |
30 | #include <linux/fcntl.h> |
31 | #include <linux/swap.h> |
32 | #include <linux/string.h> |
33 | #include <linux/init.h> |
34 | #include <linux/pagemap.h> |
35 | #include <linux/perf_event.h> |
36 | #include <linux/highmem.h> |
37 | #include <linux/spinlock.h> |
38 | #include <linux/key.h> |
39 | #include <linux/personality.h> |
40 | #include <linux/binfmts.h> |
41 | #include <linux/utsname.h> |
42 | #include <linux/pid_namespace.h> |
43 | #include <linux/module.h> |
44 | #include <linux/namei.h> |
45 | #include <linux/mount.h> |
46 | #include <linux/security.h> |
47 | #include <linux/syscalls.h> |
48 | #include <linux/tsacct_kern.h> |
49 | #include <linux/cn_proc.h> |
50 | #include <linux/audit.h> |
51 | #include <linux/tracehook.h> |
52 | #include <linux/kmod.h> |
53 | #include <linux/fsnotify.h> |
54 | #include <linux/fs_struct.h> |
55 | #include <linux/pipe_fs_i.h> |
56 | #include <linux/oom.h> |
57 | #include <linux/compat.h> |
58 | |
59 | #include <asm/uaccess.h> |
60 | #include <asm/mmu_context.h> |
61 | #include <asm/tlb.h> |
62 | |
63 | #include <trace/events/task.h> |
64 | #include "internal.h" |
65 | |
66 | int core_uses_pid; |
67 | char core_pattern[CORENAME_MAX_SIZE] = "core"; |
68 | unsigned int core_pipe_limit; |
69 | int suid_dumpable = 0; |
70 | |
71 | struct core_name { |
72 | char *corename; |
73 | int used, size; |
74 | }; |
75 | static atomic_t call_count = ATOMIC_INIT(1); |
76 | |
77 | /* The maximal length of core_pattern is also specified in sysctl.c */ |
78 | |
79 | static LIST_HEAD(formats); |
80 | static DEFINE_RWLOCK(binfmt_lock); |
81 | |
82 | int __register_binfmt(struct linux_binfmt * fmt, int insert) |
83 | { |
84 | if (!fmt) |
85 | return -EINVAL; |
86 | write_lock(&binfmt_lock); |
87 | insert ? list_add(&fmt->lh, &formats) : |
88 | list_add_tail(&fmt->lh, &formats); |
89 | write_unlock(&binfmt_lock); |
90 | return 0; |
91 | } |
92 | |
93 | EXPORT_SYMBOL(__register_binfmt); |
94 | |
95 | void unregister_binfmt(struct linux_binfmt * fmt) |
96 | { |
97 | write_lock(&binfmt_lock); |
98 | list_del(&fmt->lh); |
99 | write_unlock(&binfmt_lock); |
100 | } |
101 | |
102 | EXPORT_SYMBOL(unregister_binfmt); |
103 | |
104 | static inline void put_binfmt(struct linux_binfmt * fmt) |
105 | { |
106 | module_put(fmt->module); |
107 | } |
108 | |
109 | /* |
110 | * Note that a shared library must be both readable and executable due to |
111 | * security reasons. |
112 | * |
113 | * Also note that we take the address to load from from the file itself. |
114 | */ |
115 | SYSCALL_DEFINE1(uselib, const char __user *, library) |
116 | { |
117 | struct file *file; |
118 | char *tmp = getname(library); |
119 | int error = PTR_ERR(tmp); |
120 | static const struct open_flags uselib_flags = { |
121 | .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, |
122 | .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN, |
123 | .intent = LOOKUP_OPEN |
124 | }; |
125 | |
126 | if (IS_ERR(tmp)) |
127 | goto out; |
128 | |
129 | file = do_filp_open(AT_FDCWD, tmp, &uselib_flags, LOOKUP_FOLLOW); |
130 | putname(tmp); |
131 | error = PTR_ERR(file); |
132 | if (IS_ERR(file)) |
133 | goto out; |
134 | |
135 | error = -EINVAL; |
136 | if (!S_ISREG(file->f_path.dentry->d_inode->i_mode)) |
137 | goto exit; |
138 | |
139 | error = -EACCES; |
140 | if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) |
141 | goto exit; |
142 | |
143 | fsnotify_open(file); |
144 | |
145 | error = -ENOEXEC; |
146 | if(file->f_op) { |
147 | struct linux_binfmt * fmt; |
148 | |
149 | read_lock(&binfmt_lock); |
150 | list_for_each_entry(fmt, &formats, lh) { |
151 | if (!fmt->load_shlib) |
152 | continue; |
153 | if (!try_module_get(fmt->module)) |
154 | continue; |
155 | read_unlock(&binfmt_lock); |
156 | error = fmt->load_shlib(file); |
157 | read_lock(&binfmt_lock); |
158 | put_binfmt(fmt); |
159 | if (error != -ENOEXEC) |
160 | break; |
161 | } |
162 | read_unlock(&binfmt_lock); |
163 | } |
164 | exit: |
165 | fput(file); |
166 | out: |
167 | return error; |
168 | } |
169 | |
170 | #ifdef CONFIG_MMU |
171 | /* |
172 | * The nascent bprm->mm is not visible until exec_mmap() but it can |
173 | * use a lot of memory, account these pages in current->mm temporary |
174 | * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we |
175 | * change the counter back via acct_arg_size(0). |
176 | */ |
177 | static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) |
178 | { |
179 | struct mm_struct *mm = current->mm; |
180 | long diff = (long)(pages - bprm->vma_pages); |
181 | |
182 | if (!mm || !diff) |
183 | return; |
184 | |
185 | bprm->vma_pages = pages; |
186 | add_mm_counter(mm, MM_ANONPAGES, diff); |
187 | } |
188 | |
189 | static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, |
190 | int write) |
191 | { |
192 | struct page *page; |
193 | int ret; |
194 | |
195 | #ifdef CONFIG_STACK_GROWSUP |
196 | if (write) { |
197 | ret = expand_downwards(bprm->vma, pos); |
198 | if (ret < 0) |
199 | return NULL; |
200 | } |
201 | #endif |
202 | ret = get_user_pages(current, bprm->mm, pos, |
203 | 1, write, 1, &page, NULL); |
204 | if (ret <= 0) |
205 | return NULL; |
206 | |
207 | if (write) { |
208 | unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start; |
209 | struct rlimit *rlim; |
210 | |
211 | acct_arg_size(bprm, size / PAGE_SIZE); |
212 | |
213 | /* |
214 | * We've historically supported up to 32 pages (ARG_MAX) |
215 | * of argument strings even with small stacks |
216 | */ |
217 | if (size <= ARG_MAX) |
218 | return page; |
219 | |
220 | /* |
221 | * Limit to 1/4-th the stack size for the argv+env strings. |
222 | * This ensures that: |
223 | * - the remaining binfmt code will not run out of stack space, |
224 | * - the program will have a reasonable amount of stack left |
225 | * to work from. |
226 | */ |
227 | rlim = current->signal->rlim; |
228 | if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) { |
229 | put_page(page); |
230 | return NULL; |
231 | } |
232 | } |
233 | |
234 | return page; |
235 | } |
236 | |
237 | static void put_arg_page(struct page *page) |
238 | { |
239 | put_page(page); |
240 | } |
241 | |
242 | static void free_arg_page(struct linux_binprm *bprm, int i) |
243 | { |
244 | } |
245 | |
246 | static void free_arg_pages(struct linux_binprm *bprm) |
247 | { |
248 | } |
249 | |
250 | static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, |
251 | struct page *page) |
252 | { |
253 | flush_cache_page(bprm->vma, pos, page_to_pfn(page)); |
254 | } |
255 | |
256 | static int __bprm_mm_init(struct linux_binprm *bprm) |
257 | { |
258 | int err; |
259 | struct vm_area_struct *vma = NULL; |
260 | struct mm_struct *mm = bprm->mm; |
261 | |
262 | bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); |
263 | if (!vma) |
264 | return -ENOMEM; |
265 | |
266 | down_write(&mm->mmap_sem); |
267 | vma->vm_mm = mm; |
268 | |
269 | /* |
270 | * Place the stack at the largest stack address the architecture |
271 | * supports. Later, we'll move this to an appropriate place. We don't |
272 | * use STACK_TOP because that can depend on attributes which aren't |
273 | * configured yet. |
274 | */ |
275 | BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP); |
276 | vma->vm_end = STACK_TOP_MAX; |
277 | vma->vm_start = vma->vm_end - PAGE_SIZE; |
278 | vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP; |
279 | vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); |
280 | INIT_LIST_HEAD(&vma->anon_vma_chain); |
281 | |
282 | err = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1); |
283 | if (err) |
284 | goto err; |
285 | |
286 | err = insert_vm_struct(mm, vma); |
287 | if (err) |
288 | goto err; |
289 | |
290 | mm->stack_vm = mm->total_vm = 1; |
291 | up_write(&mm->mmap_sem); |
292 | bprm->p = vma->vm_end - sizeof(void *); |
293 | return 0; |
294 | err: |
295 | up_write(&mm->mmap_sem); |
296 | bprm->vma = NULL; |
297 | kmem_cache_free(vm_area_cachep, vma); |
298 | return err; |
299 | } |
300 | |
301 | static bool valid_arg_len(struct linux_binprm *bprm, long len) |
302 | { |
303 | return len <= MAX_ARG_STRLEN; |
304 | } |
305 | |
306 | #else |
307 | |
308 | static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) |
309 | { |
310 | } |
311 | |
312 | static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, |
313 | int write) |
314 | { |
315 | struct page *page; |
316 | |
317 | page = bprm->page[pos / PAGE_SIZE]; |
318 | if (!page && write) { |
319 | page = alloc_page(GFP_HIGHUSER|__GFP_ZERO); |
320 | if (!page) |
321 | return NULL; |
322 | bprm->page[pos / PAGE_SIZE] = page; |
323 | } |
324 | |
325 | return page; |
326 | } |
327 | |
328 | static void put_arg_page(struct page *page) |
329 | { |
330 | } |
331 | |
332 | static void free_arg_page(struct linux_binprm *bprm, int i) |
333 | { |
334 | if (bprm->page[i]) { |
335 | __free_page(bprm->page[i]); |
336 | bprm->page[i] = NULL; |
337 | } |
338 | } |
339 | |
340 | static void free_arg_pages(struct linux_binprm *bprm) |
341 | { |
342 | int i; |
343 | |
344 | for (i = 0; i < MAX_ARG_PAGES; i++) |
345 | free_arg_page(bprm, i); |
346 | } |
347 | |
348 | static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, |
349 | struct page *page) |
350 | { |
351 | } |
352 | |
353 | static int __bprm_mm_init(struct linux_binprm *bprm) |
354 | { |
355 | bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *); |
356 | return 0; |
357 | } |
358 | |
359 | static bool valid_arg_len(struct linux_binprm *bprm, long len) |
360 | { |
361 | return len <= bprm->p; |
362 | } |
363 | |
364 | #endif /* CONFIG_MMU */ |
365 | |
366 | /* |
367 | * Create a new mm_struct and populate it with a temporary stack |
368 | * vm_area_struct. We don't have enough context at this point to set the stack |
369 | * flags, permissions, and offset, so we use temporary values. We'll update |
370 | * them later in setup_arg_pages(). |
371 | */ |
372 | int bprm_mm_init(struct linux_binprm *bprm) |
373 | { |
374 | int err; |
375 | struct mm_struct *mm = NULL; |
376 | |
377 | bprm->mm = mm = mm_alloc(); |
378 | err = -ENOMEM; |
379 | if (!mm) |
380 | goto err; |
381 | |
382 | err = init_new_context(current, mm); |
383 | if (err) |
384 | goto err; |
385 | |
386 | err = __bprm_mm_init(bprm); |
387 | if (err) |
388 | goto err; |
389 | |
390 | return 0; |
391 | |
392 | err: |
393 | if (mm) { |
394 | bprm->mm = NULL; |
395 | mmdrop(mm); |
396 | } |
397 | |
398 | return err; |
399 | } |
400 | |
401 | struct user_arg_ptr { |
402 | #ifdef CONFIG_COMPAT |
403 | bool is_compat; |
404 | #endif |
405 | union { |
406 | const char __user *const __user *native; |
407 | #ifdef CONFIG_COMPAT |
408 | compat_uptr_t __user *compat; |
409 | #endif |
410 | } ptr; |
411 | }; |
412 | |
413 | static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr) |
414 | { |
415 | const char __user *native; |
416 | |
417 | #ifdef CONFIG_COMPAT |
418 | if (unlikely(argv.is_compat)) { |
419 | compat_uptr_t compat; |
420 | |
421 | if (get_user(compat, argv.ptr.compat + nr)) |
422 | return ERR_PTR(-EFAULT); |
423 | |
424 | return compat_ptr(compat); |
425 | } |
426 | #endif |
427 | |
428 | if (get_user(native, argv.ptr.native + nr)) |
429 | return ERR_PTR(-EFAULT); |
430 | |
431 | return native; |
432 | } |
433 | |
434 | /* |
435 | * count() counts the number of strings in array ARGV. |
436 | */ |
437 | static int count(struct user_arg_ptr argv, int max) |
438 | { |
439 | int i = 0; |
440 | |
441 | if (argv.ptr.native != NULL) { |
442 | for (;;) { |
443 | const char __user *p = get_user_arg_ptr(argv, i); |
444 | |
445 | if (!p) |
446 | break; |
447 | |
448 | if (IS_ERR(p)) |
449 | return -EFAULT; |
450 | |
451 | if (i++ >= max) |
452 | return -E2BIG; |
453 | |
454 | if (fatal_signal_pending(current)) |
455 | return -ERESTARTNOHAND; |
456 | cond_resched(); |
457 | } |
458 | } |
459 | return i; |
460 | } |
461 | |
462 | /* |
463 | * 'copy_strings()' copies argument/environment strings from the old |
464 | * processes's memory to the new process's stack. The call to get_user_pages() |
465 | * ensures the destination page is created and not swapped out. |
466 | */ |
467 | static int copy_strings(int argc, struct user_arg_ptr argv, |
468 | struct linux_binprm *bprm) |
469 | { |
470 | struct page *kmapped_page = NULL; |
471 | char *kaddr = NULL; |
472 | unsigned long kpos = 0; |
473 | int ret; |
474 | |
475 | while (argc-- > 0) { |
476 | const char __user *str; |
477 | int len; |
478 | unsigned long pos; |
479 | |
480 | ret = -EFAULT; |
481 | str = get_user_arg_ptr(argv, argc); |
482 | if (IS_ERR(str)) |
483 | goto out; |
484 | |
485 | len = strnlen_user(str, MAX_ARG_STRLEN); |
486 | if (!len) |
487 | goto out; |
488 | |
489 | ret = -E2BIG; |
490 | if (!valid_arg_len(bprm, len)) |
491 | goto out; |
492 | |
493 | /* We're going to work our way backwords. */ |
494 | pos = bprm->p; |
495 | str += len; |
496 | bprm->p -= len; |
497 | |
498 | while (len > 0) { |
499 | int offset, bytes_to_copy; |
500 | |
501 | if (fatal_signal_pending(current)) { |
502 | ret = -ERESTARTNOHAND; |
503 | goto out; |
504 | } |
505 | cond_resched(); |
506 | |
507 | offset = pos % PAGE_SIZE; |
508 | if (offset == 0) |
509 | offset = PAGE_SIZE; |
510 | |
511 | bytes_to_copy = offset; |
512 | if (bytes_to_copy > len) |
513 | bytes_to_copy = len; |
514 | |
515 | offset -= bytes_to_copy; |
516 | pos -= bytes_to_copy; |
517 | str -= bytes_to_copy; |
518 | len -= bytes_to_copy; |
519 | |
520 | if (!kmapped_page || kpos != (pos & PAGE_MASK)) { |
521 | struct page *page; |
522 | |
523 | page = get_arg_page(bprm, pos, 1); |
524 | if (!page) { |
525 | ret = -E2BIG; |
526 | goto out; |
527 | } |
528 | |
529 | if (kmapped_page) { |
530 | flush_kernel_dcache_page(kmapped_page); |
531 | kunmap(kmapped_page); |
532 | put_arg_page(kmapped_page); |
533 | } |
534 | kmapped_page = page; |
535 | kaddr = kmap(kmapped_page); |
536 | kpos = pos & PAGE_MASK; |
537 | flush_arg_page(bprm, kpos, kmapped_page); |
538 | } |
539 | if (copy_from_user(kaddr+offset, str, bytes_to_copy)) { |
540 | ret = -EFAULT; |
541 | goto out; |
542 | } |
543 | } |
544 | } |
545 | ret = 0; |
546 | out: |
547 | if (kmapped_page) { |
548 | flush_kernel_dcache_page(kmapped_page); |
549 | kunmap(kmapped_page); |
550 | put_arg_page(kmapped_page); |
551 | } |
552 | return ret; |
553 | } |
554 | |
555 | /* |
556 | * Like copy_strings, but get argv and its values from kernel memory. |
557 | */ |
558 | int copy_strings_kernel(int argc, const char *const *__argv, |
559 | struct linux_binprm *bprm) |
560 | { |
561 | int r; |
562 | mm_segment_t oldfs = get_fs(); |
563 | struct user_arg_ptr argv = { |
564 | .ptr.native = (const char __user *const __user *)__argv, |
565 | }; |
566 | |
567 | set_fs(KERNEL_DS); |
568 | r = copy_strings(argc, argv, bprm); |
569 | set_fs(oldfs); |
570 | |
571 | return r; |
572 | } |
573 | EXPORT_SYMBOL(copy_strings_kernel); |
574 | |
575 | #ifdef CONFIG_MMU |
576 | |
577 | /* |
578 | * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once |
579 | * the binfmt code determines where the new stack should reside, we shift it to |
580 | * its final location. The process proceeds as follows: |
581 | * |
582 | * 1) Use shift to calculate the new vma endpoints. |
583 | * 2) Extend vma to cover both the old and new ranges. This ensures the |
584 | * arguments passed to subsequent functions are consistent. |
585 | * 3) Move vma's page tables to the new range. |
586 | * 4) Free up any cleared pgd range. |
587 | * 5) Shrink the vma to cover only the new range. |
588 | */ |
589 | static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift) |
590 | { |
591 | struct mm_struct *mm = vma->vm_mm; |
592 | unsigned long old_start = vma->vm_start; |
593 | unsigned long old_end = vma->vm_end; |
594 | unsigned long length = old_end - old_start; |
595 | unsigned long new_start = old_start - shift; |
596 | unsigned long new_end = old_end - shift; |
597 | struct mmu_gather tlb; |
598 | |
599 | BUG_ON(new_start > new_end); |
600 | |
601 | /* |
602 | * ensure there are no vmas between where we want to go |
603 | * and where we are |
604 | */ |
605 | if (vma != find_vma(mm, new_start)) |
606 | return -EFAULT; |
607 | |
608 | /* |
609 | * cover the whole range: [new_start, old_end) |
610 | */ |
611 | if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL)) |
612 | return -ENOMEM; |
613 | |
614 | /* |
615 | * move the page tables downwards, on failure we rely on |
616 | * process cleanup to remove whatever mess we made. |
617 | */ |
618 | if (length != move_page_tables(vma, old_start, |
619 | vma, new_start, length)) |
620 | return -ENOMEM; |
621 | |
622 | lru_add_drain(); |
623 | tlb_gather_mmu(&tlb, mm, 0); |
624 | if (new_end > old_start) { |
625 | /* |
626 | * when the old and new regions overlap clear from new_end. |
627 | */ |
628 | free_pgd_range(&tlb, new_end, old_end, new_end, |
629 | vma->vm_next ? vma->vm_next->vm_start : 0); |
630 | } else { |
631 | /* |
632 | * otherwise, clean from old_start; this is done to not touch |
633 | * the address space in [new_end, old_start) some architectures |
634 | * have constraints on va-space that make this illegal (IA64) - |
635 | * for the others its just a little faster. |
636 | */ |
637 | free_pgd_range(&tlb, old_start, old_end, new_end, |
638 | vma->vm_next ? vma->vm_next->vm_start : 0); |
639 | } |
640 | tlb_finish_mmu(&tlb, new_end, old_end); |
641 | |
642 | /* |
643 | * Shrink the vma to just the new range. Always succeeds. |
644 | */ |
645 | vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL); |
646 | |
647 | return 0; |
648 | } |
649 | |
650 | /* |
651 | * Finalizes the stack vm_area_struct. The flags and permissions are updated, |
652 | * the stack is optionally relocated, and some extra space is added. |
653 | */ |
654 | int setup_arg_pages(struct linux_binprm *bprm, |
655 | unsigned long stack_top, |
656 | int executable_stack) |
657 | { |
658 | unsigned long ret; |
659 | unsigned long stack_shift; |
660 | struct mm_struct *mm = current->mm; |
661 | struct vm_area_struct *vma = bprm->vma; |
662 | struct vm_area_struct *prev = NULL; |
663 | unsigned long vm_flags; |
664 | unsigned long stack_base; |
665 | unsigned long stack_size; |
666 | unsigned long stack_expand; |
667 | unsigned long rlim_stack; |
668 | |
669 | #ifdef CONFIG_STACK_GROWSUP |
670 | /* Limit stack size to 1GB */ |
671 | stack_base = rlimit_max(RLIMIT_STACK); |
672 | if (stack_base > (1 << 30)) |
673 | stack_base = 1 << 30; |
674 | |
675 | /* Make sure we didn't let the argument array grow too large. */ |
676 | if (vma->vm_end - vma->vm_start > stack_base) |
677 | return -ENOMEM; |
678 | |
679 | stack_base = PAGE_ALIGN(stack_top - stack_base); |
680 | |
681 | stack_shift = vma->vm_start - stack_base; |
682 | mm->arg_start = bprm->p - stack_shift; |
683 | bprm->p = vma->vm_end - stack_shift; |
684 | #else |
685 | stack_top = arch_align_stack(stack_top); |
686 | stack_top = PAGE_ALIGN(stack_top); |
687 | |
688 | if (unlikely(stack_top < mmap_min_addr) || |
689 | unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr)) |
690 | return -ENOMEM; |
691 | |
692 | stack_shift = vma->vm_end - stack_top; |
693 | |
694 | bprm->p -= stack_shift; |
695 | mm->arg_start = bprm->p; |
696 | #endif |
697 | |
698 | if (bprm->loader) |
699 | bprm->loader -= stack_shift; |
700 | bprm->exec -= stack_shift; |
701 | |
702 | down_write(&mm->mmap_sem); |
703 | vm_flags = VM_STACK_FLAGS; |
704 | |
705 | /* |
706 | * Adjust stack execute permissions; explicitly enable for |
707 | * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone |
708 | * (arch default) otherwise. |
709 | */ |
710 | if (unlikely(executable_stack == EXSTACK_ENABLE_X)) |
711 | vm_flags |= VM_EXEC; |
712 | else if (executable_stack == EXSTACK_DISABLE_X) |
713 | vm_flags &= ~VM_EXEC; |
714 | vm_flags |= mm->def_flags; |
715 | vm_flags |= VM_STACK_INCOMPLETE_SETUP; |
716 | |
717 | ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end, |
718 | vm_flags); |
719 | if (ret) |
720 | goto out_unlock; |
721 | BUG_ON(prev != vma); |
722 | |
723 | /* Move stack pages down in memory. */ |
724 | if (stack_shift) { |
725 | ret = shift_arg_pages(vma, stack_shift); |
726 | if (ret) |
727 | goto out_unlock; |
728 | } |
729 | |
730 | /* mprotect_fixup is overkill to remove the temporary stack flags */ |
731 | vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP; |
732 | |
733 | stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */ |
734 | stack_size = vma->vm_end - vma->vm_start; |
735 | /* |
736 | * Align this down to a page boundary as expand_stack |
737 | * will align it up. |
738 | */ |
739 | rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK; |
740 | #ifdef CONFIG_STACK_GROWSUP |
741 | if (stack_size + stack_expand > rlim_stack) |
742 | stack_base = vma->vm_start + rlim_stack; |
743 | else |
744 | stack_base = vma->vm_end + stack_expand; |
745 | #else |
746 | if (stack_size + stack_expand > rlim_stack) |
747 | stack_base = vma->vm_end - rlim_stack; |
748 | else |
749 | stack_base = vma->vm_start - stack_expand; |
750 | #endif |
751 | current->mm->start_stack = bprm->p; |
752 | ret = expand_stack(vma, stack_base); |
753 | if (ret) |
754 | ret = -EFAULT; |
755 | |
756 | out_unlock: |
757 | up_write(&mm->mmap_sem); |
758 | return ret; |
759 | } |
760 | EXPORT_SYMBOL(setup_arg_pages); |
761 | |
762 | #endif /* CONFIG_MMU */ |
763 | |
764 | struct file *open_exec(const char *name) |
765 | { |
766 | struct file *file; |
767 | int err; |
768 | static const struct open_flags open_exec_flags = { |
769 | .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, |
770 | .acc_mode = MAY_EXEC | MAY_OPEN, |
771 | .intent = LOOKUP_OPEN |
772 | }; |
773 | |
774 | file = do_filp_open(AT_FDCWD, name, &open_exec_flags, LOOKUP_FOLLOW); |
775 | if (IS_ERR(file)) |
776 | goto out; |
777 | |
778 | err = -EACCES; |
779 | if (!S_ISREG(file->f_path.dentry->d_inode->i_mode)) |
780 | goto exit; |
781 | |
782 | if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) |
783 | goto exit; |
784 | |
785 | fsnotify_open(file); |
786 | |
787 | err = deny_write_access(file); |
788 | if (err) |
789 | goto exit; |
790 | |
791 | out: |
792 | return file; |
793 | |
794 | exit: |
795 | fput(file); |
796 | return ERR_PTR(err); |
797 | } |
798 | EXPORT_SYMBOL(open_exec); |
799 | |
800 | int kernel_read(struct file *file, loff_t offset, |
801 | char *addr, unsigned long count) |
802 | { |
803 | mm_segment_t old_fs; |
804 | loff_t pos = offset; |
805 | int result; |
806 | |
807 | old_fs = get_fs(); |
808 | set_fs(get_ds()); |
809 | /* The cast to a user pointer is valid due to the set_fs() */ |
810 | result = vfs_read(file, (void __user *)addr, count, &pos); |
811 | set_fs(old_fs); |
812 | return result; |
813 | } |
814 | |
815 | EXPORT_SYMBOL(kernel_read); |
816 | |
817 | static int exec_mmap(struct mm_struct *mm) |
818 | { |
819 | struct task_struct *tsk; |
820 | struct mm_struct * old_mm, *active_mm; |
821 | |
822 | /* Notify parent that we're no longer interested in the old VM */ |
823 | tsk = current; |
824 | old_mm = current->mm; |
825 | sync_mm_rss(tsk, old_mm); |
826 | mm_release(tsk, old_mm); |
827 | |
828 | if (old_mm) { |
829 | /* |
830 | * Make sure that if there is a core dump in progress |
831 | * for the old mm, we get out and die instead of going |
832 | * through with the exec. We must hold mmap_sem around |
833 | * checking core_state and changing tsk->mm. |
834 | */ |
835 | down_read(&old_mm->mmap_sem); |
836 | if (unlikely(old_mm->core_state)) { |
837 | up_read(&old_mm->mmap_sem); |
838 | return -EINTR; |
839 | } |
840 | } |
841 | task_lock(tsk); |
842 | active_mm = tsk->active_mm; |
843 | tsk->mm = mm; |
844 | tsk->active_mm = mm; |
845 | activate_mm(active_mm, mm); |
846 | task_unlock(tsk); |
847 | arch_pick_mmap_layout(mm); |
848 | if (old_mm) { |
849 | up_read(&old_mm->mmap_sem); |
850 | BUG_ON(active_mm != old_mm); |
851 | mm_update_next_owner(old_mm); |
852 | mmput(old_mm); |
853 | return 0; |
854 | } |
855 | mmdrop(active_mm); |
856 | return 0; |
857 | } |
858 | |
859 | /* |
860 | * This function makes sure the current process has its own signal table, |
861 | * so that flush_signal_handlers can later reset the handlers without |
862 | * disturbing other processes. (Other processes might share the signal |
863 | * table via the CLONE_SIGHAND option to clone().) |
864 | */ |
865 | static int de_thread(struct task_struct *tsk) |
866 | { |
867 | struct signal_struct *sig = tsk->signal; |
868 | struct sighand_struct *oldsighand = tsk->sighand; |
869 | spinlock_t *lock = &oldsighand->siglock; |
870 | |
871 | if (thread_group_empty(tsk)) |
872 | goto no_thread_group; |
873 | |
874 | /* |
875 | * Kill all other threads in the thread group. |
876 | */ |
877 | spin_lock_irq(lock); |
878 | if (signal_group_exit(sig)) { |
879 | /* |
880 | * Another group action in progress, just |
881 | * return so that the signal is processed. |
882 | */ |
883 | spin_unlock_irq(lock); |
884 | return -EAGAIN; |
885 | } |
886 | |
887 | sig->group_exit_task = tsk; |
888 | sig->notify_count = zap_other_threads(tsk); |
889 | if (!thread_group_leader(tsk)) |
890 | sig->notify_count--; |
891 | |
892 | while (sig->notify_count) { |
893 | __set_current_state(TASK_UNINTERRUPTIBLE); |
894 | spin_unlock_irq(lock); |
895 | schedule(); |
896 | spin_lock_irq(lock); |
897 | } |
898 | spin_unlock_irq(lock); |
899 | |
900 | /* |
901 | * At this point all other threads have exited, all we have to |
902 | * do is to wait for the thread group leader to become inactive, |
903 | * and to assume its PID: |
904 | */ |
905 | if (!thread_group_leader(tsk)) { |
906 | struct task_struct *leader = tsk->group_leader; |
907 | |
908 | sig->notify_count = -1; /* for exit_notify() */ |
909 | for (;;) { |
910 | write_lock_irq(&tasklist_lock); |
911 | if (likely(leader->exit_state)) |
912 | break; |
913 | __set_current_state(TASK_UNINTERRUPTIBLE); |
914 | write_unlock_irq(&tasklist_lock); |
915 | schedule(); |
916 | } |
917 | |
918 | /* |
919 | * The only record we have of the real-time age of a |
920 | * process, regardless of execs it's done, is start_time. |
921 | * All the past CPU time is accumulated in signal_struct |
922 | * from sister threads now dead. But in this non-leader |
923 | * exec, nothing survives from the original leader thread, |
924 | * whose birth marks the true age of this process now. |
925 | * When we take on its identity by switching to its PID, we |
926 | * also take its birthdate (always earlier than our own). |
927 | */ |
928 | tsk->start_time = leader->start_time; |
929 | |
930 | BUG_ON(!same_thread_group(leader, tsk)); |
931 | BUG_ON(has_group_leader_pid(tsk)); |
932 | /* |
933 | * An exec() starts a new thread group with the |
934 | * TGID of the previous thread group. Rehash the |
935 | * two threads with a switched PID, and release |
936 | * the former thread group leader: |
937 | */ |
938 | |
939 | /* Become a process group leader with the old leader's pid. |
940 | * The old leader becomes a thread of the this thread group. |
941 | * Note: The old leader also uses this pid until release_task |
942 | * is called. Odd but simple and correct. |
943 | */ |
944 | detach_pid(tsk, PIDTYPE_PID); |
945 | tsk->pid = leader->pid; |
946 | attach_pid(tsk, PIDTYPE_PID, task_pid(leader)); |
947 | transfer_pid(leader, tsk, PIDTYPE_PGID); |
948 | transfer_pid(leader, tsk, PIDTYPE_SID); |
949 | |
950 | list_replace_rcu(&leader->tasks, &tsk->tasks); |
951 | list_replace_init(&leader->sibling, &tsk->sibling); |
952 | |
953 | tsk->group_leader = tsk; |
954 | leader->group_leader = tsk; |
955 | |
956 | tsk->exit_signal = SIGCHLD; |
957 | leader->exit_signal = -1; |
958 | |
959 | BUG_ON(leader->exit_state != EXIT_ZOMBIE); |
960 | leader->exit_state = EXIT_DEAD; |
961 | |
962 | /* |
963 | * We are going to release_task()->ptrace_unlink() silently, |
964 | * the tracer can sleep in do_wait(). EXIT_DEAD guarantees |
965 | * the tracer wont't block again waiting for this thread. |
966 | */ |
967 | if (unlikely(leader->ptrace)) |
968 | __wake_up_parent(leader, leader->parent); |
969 | write_unlock_irq(&tasklist_lock); |
970 | |
971 | release_task(leader); |
972 | } |
973 | |
974 | sig->group_exit_task = NULL; |
975 | sig->notify_count = 0; |
976 | |
977 | no_thread_group: |
978 | if (current->mm) |
979 | setmax_mm_hiwater_rss(&sig->maxrss, current->mm); |
980 | |
981 | exit_itimers(sig); |
982 | flush_itimer_signals(); |
983 | |
984 | if (atomic_read(&oldsighand->count) != 1) { |
985 | struct sighand_struct *newsighand; |
986 | /* |
987 | * This ->sighand is shared with the CLONE_SIGHAND |
988 | * but not CLONE_THREAD task, switch to the new one. |
989 | */ |
990 | newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); |
991 | if (!newsighand) |
992 | return -ENOMEM; |
993 | |
994 | atomic_set(&newsighand->count, 1); |
995 | memcpy(newsighand->action, oldsighand->action, |
996 | sizeof(newsighand->action)); |
997 | |
998 | write_lock_irq(&tasklist_lock); |
999 | spin_lock(&oldsighand->siglock); |
1000 | rcu_assign_pointer(tsk->sighand, newsighand); |
1001 | spin_unlock(&oldsighand->siglock); |
1002 | write_unlock_irq(&tasklist_lock); |
1003 | |
1004 | __cleanup_sighand(oldsighand); |
1005 | } |
1006 | |
1007 | BUG_ON(!thread_group_leader(tsk)); |
1008 | return 0; |
1009 | } |
1010 | |
1011 | /* |
1012 | * These functions flushes out all traces of the currently running executable |
1013 | * so that a new one can be started |
1014 | */ |
1015 | static void flush_old_files(struct files_struct * files) |
1016 | { |
1017 | long j = -1; |
1018 | struct fdtable *fdt; |
1019 | |
1020 | spin_lock(&files->file_lock); |
1021 | for (;;) { |
1022 | unsigned long set, i; |
1023 | |
1024 | j++; |
1025 | i = j * __NFDBITS; |
1026 | fdt = files_fdtable(files); |
1027 | if (i >= fdt->max_fds) |
1028 | break; |
1029 | set = fdt->close_on_exec->fds_bits[j]; |
1030 | if (!set) |
1031 | continue; |
1032 | fdt->close_on_exec->fds_bits[j] = 0; |
1033 | spin_unlock(&files->file_lock); |
1034 | for ( ; set ; i++,set >>= 1) { |
1035 | if (set & 1) { |
1036 | sys_close(i); |
1037 | } |
1038 | } |
1039 | spin_lock(&files->file_lock); |
1040 | |
1041 | } |
1042 | spin_unlock(&files->file_lock); |
1043 | } |
1044 | |
1045 | char *get_task_comm(char *buf, struct task_struct *tsk) |
1046 | { |
1047 | /* buf must be at least sizeof(tsk->comm) in size */ |
1048 | task_lock(tsk); |
1049 | strncpy(buf, tsk->comm, sizeof(tsk->comm)); |
1050 | task_unlock(tsk); |
1051 | return buf; |
1052 | } |
1053 | EXPORT_SYMBOL_GPL(get_task_comm); |
1054 | |
1055 | void set_task_comm(struct task_struct *tsk, char *buf) |
1056 | { |
1057 | task_lock(tsk); |
1058 | |
1059 | trace_task_rename(tsk, buf); |
1060 | |
1061 | /* |
1062 | * Threads may access current->comm without holding |
1063 | * the task lock, so write the string carefully. |
1064 | * Readers without a lock may see incomplete new |
1065 | * names but are safe from non-terminating string reads. |
1066 | */ |
1067 | memset(tsk->comm, 0, TASK_COMM_LEN); |
1068 | wmb(); |
1069 | strlcpy(tsk->comm, buf, sizeof(tsk->comm)); |
1070 | task_unlock(tsk); |
1071 | perf_event_comm(tsk); |
1072 | } |
1073 | |
1074 | static void filename_to_taskname(char *tcomm, const char *fn, unsigned int len) |
1075 | { |
1076 | int i, ch; |
1077 | |
1078 | /* Copies the binary name from after last slash */ |
1079 | for (i = 0; (ch = *(fn++)) != '\0';) { |
1080 | if (ch == '/') |
1081 | i = 0; /* overwrite what we wrote */ |
1082 | else |
1083 | if (i < len - 1) |
1084 | tcomm[i++] = ch; |
1085 | } |
1086 | tcomm[i] = '\0'; |
1087 | } |
1088 | |
1089 | int flush_old_exec(struct linux_binprm * bprm) |
1090 | { |
1091 | int retval; |
1092 | |
1093 | /* |
1094 | * Make sure we have a private signal table and that |
1095 | * we are unassociated from the previous thread group. |
1096 | */ |
1097 | retval = de_thread(current); |
1098 | if (retval) |
1099 | goto out; |
1100 | |
1101 | set_mm_exe_file(bprm->mm, bprm->file); |
1102 | |
1103 | filename_to_taskname(bprm->tcomm, bprm->filename, sizeof(bprm->tcomm)); |
1104 | /* |
1105 | * Release all of the old mmap stuff |
1106 | */ |
1107 | acct_arg_size(bprm, 0); |
1108 | retval = exec_mmap(bprm->mm); |
1109 | if (retval) |
1110 | goto out; |
1111 | |
1112 | bprm->mm = NULL; /* We're using it now */ |
1113 | |
1114 | set_fs(USER_DS); |
1115 | current->flags &= ~(PF_RANDOMIZE | PF_KTHREAD); |
1116 | flush_thread(); |
1117 | current->personality &= ~bprm->per_clear; |
1118 | |
1119 | return 0; |
1120 | |
1121 | out: |
1122 | return retval; |
1123 | } |
1124 | EXPORT_SYMBOL(flush_old_exec); |
1125 | |
1126 | void would_dump(struct linux_binprm *bprm, struct file *file) |
1127 | { |
1128 | if (inode_permission(file->f_path.dentry->d_inode, MAY_READ) < 0) |
1129 | bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP; |
1130 | } |
1131 | EXPORT_SYMBOL(would_dump); |
1132 | |
1133 | void setup_new_exec(struct linux_binprm * bprm) |
1134 | { |
1135 | arch_pick_mmap_layout(current->mm); |
1136 | |
1137 | /* This is the point of no return */ |
1138 | current->sas_ss_sp = current->sas_ss_size = 0; |
1139 | |
1140 | if (current_euid() == current_uid() && current_egid() == current_gid()) |
1141 | set_dumpable(current->mm, 1); |
1142 | else |
1143 | set_dumpable(current->mm, suid_dumpable); |
1144 | |
1145 | set_task_comm(current, bprm->tcomm); |
1146 | |
1147 | /* Set the new mm task size. We have to do that late because it may |
1148 | * depend on TIF_32BIT which is only updated in flush_thread() on |
1149 | * some architectures like powerpc |
1150 | */ |
1151 | current->mm->task_size = TASK_SIZE; |
1152 | |
1153 | /* install the new credentials */ |
1154 | if (bprm->cred->uid != current_euid() || |
1155 | bprm->cred->gid != current_egid()) { |
1156 | current->pdeath_signal = 0; |
1157 | } else { |
1158 | would_dump(bprm, bprm->file); |
1159 | if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) |
1160 | set_dumpable(current->mm, suid_dumpable); |
1161 | } |
1162 | |
1163 | /* |
1164 | * Flush performance counters when crossing a |
1165 | * security domain: |
1166 | */ |
1167 | if (!get_dumpable(current->mm)) |
1168 | perf_event_exit_task(current); |
1169 | |
1170 | /* An exec changes our domain. We are no longer part of the thread |
1171 | group */ |
1172 | |
1173 | current->self_exec_id++; |
1174 | |
1175 | flush_signal_handlers(current, 0); |
1176 | flush_old_files(current->files); |
1177 | } |
1178 | EXPORT_SYMBOL(setup_new_exec); |
1179 | |
1180 | /* |
1181 | * Prepare credentials and lock ->cred_guard_mutex. |
1182 | * install_exec_creds() commits the new creds and drops the lock. |
1183 | * Or, if exec fails before, free_bprm() should release ->cred and |
1184 | * and unlock. |
1185 | */ |
1186 | int prepare_bprm_creds(struct linux_binprm *bprm) |
1187 | { |
1188 | if (mutex_lock_interruptible(¤t->signal->cred_guard_mutex)) |
1189 | return -ERESTARTNOINTR; |
1190 | |
1191 | bprm->cred = prepare_exec_creds(); |
1192 | if (likely(bprm->cred)) |
1193 | return 0; |
1194 | |
1195 | mutex_unlock(¤t->signal->cred_guard_mutex); |
1196 | return -ENOMEM; |
1197 | } |
1198 | |
1199 | void free_bprm(struct linux_binprm *bprm) |
1200 | { |
1201 | free_arg_pages(bprm); |
1202 | if (bprm->cred) { |
1203 | mutex_unlock(¤t->signal->cred_guard_mutex); |
1204 | abort_creds(bprm->cred); |
1205 | } |
1206 | kfree(bprm); |
1207 | } |
1208 | |
1209 | /* |
1210 | * install the new credentials for this executable |
1211 | */ |
1212 | void install_exec_creds(struct linux_binprm *bprm) |
1213 | { |
1214 | security_bprm_committing_creds(bprm); |
1215 | |
1216 | commit_creds(bprm->cred); |
1217 | bprm->cred = NULL; |
1218 | /* |
1219 | * cred_guard_mutex must be held at least to this point to prevent |
1220 | * ptrace_attach() from altering our determination of the task's |
1221 | * credentials; any time after this it may be unlocked. |
1222 | */ |
1223 | security_bprm_committed_creds(bprm); |
1224 | mutex_unlock(¤t->signal->cred_guard_mutex); |
1225 | } |
1226 | EXPORT_SYMBOL(install_exec_creds); |
1227 | |
1228 | /* |
1229 | * determine how safe it is to execute the proposed program |
1230 | * - the caller must hold ->cred_guard_mutex to protect against |
1231 | * PTRACE_ATTACH |
1232 | */ |
1233 | static int check_unsafe_exec(struct linux_binprm *bprm) |
1234 | { |
1235 | struct task_struct *p = current, *t; |
1236 | unsigned n_fs; |
1237 | int res = 0; |
1238 | |
1239 | if (p->ptrace) { |
1240 | if (p->ptrace & PT_PTRACE_CAP) |
1241 | bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP; |
1242 | else |
1243 | bprm->unsafe |= LSM_UNSAFE_PTRACE; |
1244 | } |
1245 | |
1246 | n_fs = 1; |
1247 | spin_lock(&p->fs->lock); |
1248 | rcu_read_lock(); |
1249 | for (t = next_thread(p); t != p; t = next_thread(t)) { |
1250 | if (t->fs == p->fs) |
1251 | n_fs++; |
1252 | } |
1253 | rcu_read_unlock(); |
1254 | |
1255 | if (p->fs->users > n_fs) { |
1256 | bprm->unsafe |= LSM_UNSAFE_SHARE; |
1257 | } else { |
1258 | res = -EAGAIN; |
1259 | if (!p->fs->in_exec) { |
1260 | p->fs->in_exec = 1; |
1261 | res = 1; |
1262 | } |
1263 | } |
1264 | spin_unlock(&p->fs->lock); |
1265 | |
1266 | return res; |
1267 | } |
1268 | |
1269 | /* |
1270 | * Fill the binprm structure from the inode. |
1271 | * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes |
1272 | * |
1273 | * This may be called multiple times for binary chains (scripts for example). |
1274 | */ |
1275 | int prepare_binprm(struct linux_binprm *bprm) |
1276 | { |
1277 | umode_t mode; |
1278 | struct inode * inode = bprm->file->f_path.dentry->d_inode; |
1279 | int retval; |
1280 | |
1281 | mode = inode->i_mode; |
1282 | if (bprm->file->f_op == NULL) |
1283 | return -EACCES; |
1284 | |
1285 | /* clear any previous set[ug]id data from a previous binary */ |
1286 | bprm->cred->euid = current_euid(); |
1287 | bprm->cred->egid = current_egid(); |
1288 | |
1289 | if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) { |
1290 | /* Set-uid? */ |
1291 | if (mode & S_ISUID) { |
1292 | bprm->per_clear |= PER_CLEAR_ON_SETID; |
1293 | bprm->cred->euid = inode->i_uid; |
1294 | } |
1295 | |
1296 | /* Set-gid? */ |
1297 | /* |
1298 | * If setgid is set but no group execute bit then this |
1299 | * is a candidate for mandatory locking, not a setgid |
1300 | * executable. |
1301 | */ |
1302 | if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { |
1303 | bprm->per_clear |= PER_CLEAR_ON_SETID; |
1304 | bprm->cred->egid = inode->i_gid; |
1305 | } |
1306 | } |
1307 | |
1308 | /* fill in binprm security blob */ |
1309 | retval = security_bprm_set_creds(bprm); |
1310 | if (retval) |
1311 | return retval; |
1312 | bprm->cred_prepared = 1; |
1313 | |
1314 | memset(bprm->buf, 0, BINPRM_BUF_SIZE); |
1315 | return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE); |
1316 | } |
1317 | |
1318 | EXPORT_SYMBOL(prepare_binprm); |
1319 | |
1320 | /* |
1321 | * Arguments are '\0' separated strings found at the location bprm->p |
1322 | * points to; chop off the first by relocating brpm->p to right after |
1323 | * the first '\0' encountered. |
1324 | */ |
1325 | int remove_arg_zero(struct linux_binprm *bprm) |
1326 | { |
1327 | int ret = 0; |
1328 | unsigned long offset; |
1329 | char *kaddr; |
1330 | struct page *page; |
1331 | |
1332 | if (!bprm->argc) |
1333 | return 0; |
1334 | |
1335 | do { |
1336 | offset = bprm->p & ~PAGE_MASK; |
1337 | page = get_arg_page(bprm, bprm->p, 0); |
1338 | if (!page) { |
1339 | ret = -EFAULT; |
1340 | goto out; |
1341 | } |
1342 | kaddr = kmap_atomic(page, KM_USER0); |
1343 | |
1344 | for (; offset < PAGE_SIZE && kaddr[offset]; |
1345 | offset++, bprm->p++) |
1346 | ; |
1347 | |
1348 | kunmap_atomic(kaddr, KM_USER0); |
1349 | put_arg_page(page); |
1350 | |
1351 | if (offset == PAGE_SIZE) |
1352 | free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1); |
1353 | } while (offset == PAGE_SIZE); |
1354 | |
1355 | bprm->p++; |
1356 | bprm->argc--; |
1357 | ret = 0; |
1358 | |
1359 | out: |
1360 | return ret; |
1361 | } |
1362 | EXPORT_SYMBOL(remove_arg_zero); |
1363 | |
1364 | /* |
1365 | * cycle the list of binary formats handler, until one recognizes the image |
1366 | */ |
1367 | int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs) |
1368 | { |
1369 | unsigned int depth = bprm->recursion_depth; |
1370 | int try,retval; |
1371 | struct linux_binfmt *fmt; |
1372 | pid_t old_pid; |
1373 | |
1374 | retval = security_bprm_check(bprm); |
1375 | if (retval) |
1376 | return retval; |
1377 | |
1378 | retval = audit_bprm(bprm); |
1379 | if (retval) |
1380 | return retval; |
1381 | |
1382 | /* Need to fetch pid before load_binary changes it */ |
1383 | rcu_read_lock(); |
1384 | old_pid = task_pid_nr_ns(current, task_active_pid_ns(current->parent)); |
1385 | rcu_read_unlock(); |
1386 | |
1387 | retval = -ENOENT; |
1388 | for (try=0; try<2; try++) { |
1389 | read_lock(&binfmt_lock); |
1390 | list_for_each_entry(fmt, &formats, lh) { |
1391 | int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary; |
1392 | if (!fn) |
1393 | continue; |
1394 | if (!try_module_get(fmt->module)) |
1395 | continue; |
1396 | read_unlock(&binfmt_lock); |
1397 | retval = fn(bprm, regs); |
1398 | /* |
1399 | * Restore the depth counter to its starting value |
1400 | * in this call, so we don't have to rely on every |
1401 | * load_binary function to restore it on return. |
1402 | */ |
1403 | bprm->recursion_depth = depth; |
1404 | if (retval >= 0) { |
1405 | if (depth == 0) |
1406 | ptrace_event(PTRACE_EVENT_EXEC, |
1407 | old_pid); |
1408 | put_binfmt(fmt); |
1409 | allow_write_access(bprm->file); |
1410 | if (bprm->file) |
1411 | fput(bprm->file); |
1412 | bprm->file = NULL; |
1413 | current->did_exec = 1; |
1414 | proc_exec_connector(current); |
1415 | return retval; |
1416 | } |
1417 | read_lock(&binfmt_lock); |
1418 | put_binfmt(fmt); |
1419 | if (retval != -ENOEXEC || bprm->mm == NULL) |
1420 | break; |
1421 | if (!bprm->file) { |
1422 | read_unlock(&binfmt_lock); |
1423 | return retval; |
1424 | } |
1425 | } |
1426 | read_unlock(&binfmt_lock); |
1427 | #ifdef CONFIG_MODULES |
1428 | if (retval != -ENOEXEC || bprm->mm == NULL) { |
1429 | break; |
1430 | } else { |
1431 | #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e)) |
1432 | if (printable(bprm->buf[0]) && |
1433 | printable(bprm->buf[1]) && |
1434 | printable(bprm->buf[2]) && |
1435 | printable(bprm->buf[3])) |
1436 | break; /* -ENOEXEC */ |
1437 | if (try) |
1438 | break; /* -ENOEXEC */ |
1439 | request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2])); |
1440 | } |
1441 | #else |
1442 | break; |
1443 | #endif |
1444 | } |
1445 | return retval; |
1446 | } |
1447 | |
1448 | EXPORT_SYMBOL(search_binary_handler); |
1449 | |
1450 | /* |
1451 | * sys_execve() executes a new program. |
1452 | */ |
1453 | static int do_execve_common(const char *filename, |
1454 | struct user_arg_ptr argv, |
1455 | struct user_arg_ptr envp, |
1456 | struct pt_regs *regs) |
1457 | { |
1458 | struct linux_binprm *bprm; |
1459 | struct file *file; |
1460 | struct files_struct *displaced; |
1461 | bool clear_in_exec; |
1462 | int retval; |
1463 | const struct cred *cred = current_cred(); |
1464 | |
1465 | /* |
1466 | * We move the actual failure in case of RLIMIT_NPROC excess from |
1467 | * set*uid() to execve() because too many poorly written programs |
1468 | * don't check setuid() return code. Here we additionally recheck |
1469 | * whether NPROC limit is still exceeded. |
1470 | */ |
1471 | if ((current->flags & PF_NPROC_EXCEEDED) && |
1472 | atomic_read(&cred->user->processes) > rlimit(RLIMIT_NPROC)) { |
1473 | retval = -EAGAIN; |
1474 | goto out_ret; |
1475 | } |
1476 | |
1477 | /* We're below the limit (still or again), so we don't want to make |
1478 | * further execve() calls fail. */ |
1479 | current->flags &= ~PF_NPROC_EXCEEDED; |
1480 | |
1481 | retval = unshare_files(&displaced); |
1482 | if (retval) |
1483 | goto out_ret; |
1484 | |
1485 | retval = -ENOMEM; |
1486 | bprm = kzalloc(sizeof(*bprm), GFP_KERNEL); |
1487 | if (!bprm) |
1488 | goto out_files; |
1489 | |
1490 | retval = prepare_bprm_creds(bprm); |
1491 | if (retval) |
1492 | goto out_free; |
1493 | |
1494 | retval = check_unsafe_exec(bprm); |
1495 | if (retval < 0) |
1496 | goto out_free; |
1497 | clear_in_exec = retval; |
1498 | current->in_execve = 1; |
1499 | |
1500 | file = open_exec(filename); |
1501 | retval = PTR_ERR(file); |
1502 | if (IS_ERR(file)) |
1503 | goto out_unmark; |
1504 | |
1505 | sched_exec(); |
1506 | |
1507 | bprm->file = file; |
1508 | bprm->filename = filename; |
1509 | bprm->interp = filename; |
1510 | |
1511 | retval = bprm_mm_init(bprm); |
1512 | if (retval) |
1513 | goto out_file; |
1514 | |
1515 | bprm->argc = count(argv, MAX_ARG_STRINGS); |
1516 | if ((retval = bprm->argc) < 0) |
1517 | goto out; |
1518 | |
1519 | bprm->envc = count(envp, MAX_ARG_STRINGS); |
1520 | if ((retval = bprm->envc) < 0) |
1521 | goto out; |
1522 | |
1523 | retval = prepare_binprm(bprm); |
1524 | if (retval < 0) |
1525 | goto out; |
1526 | |
1527 | retval = copy_strings_kernel(1, &bprm->filename, bprm); |
1528 | if (retval < 0) |
1529 | goto out; |
1530 | |
1531 | bprm->exec = bprm->p; |
1532 | retval = copy_strings(bprm->envc, envp, bprm); |
1533 | if (retval < 0) |
1534 | goto out; |
1535 | |
1536 | retval = copy_strings(bprm->argc, argv, bprm); |
1537 | if (retval < 0) |
1538 | goto out; |
1539 | |
1540 | retval = search_binary_handler(bprm,regs); |
1541 | if (retval < 0) |
1542 | goto out; |
1543 | |
1544 | /* execve succeeded */ |
1545 | current->fs->in_exec = 0; |
1546 | current->in_execve = 0; |
1547 | acct_update_integrals(current); |
1548 | free_bprm(bprm); |
1549 | if (displaced) |
1550 | put_files_struct(displaced); |
1551 | return retval; |
1552 | |
1553 | out: |
1554 | if (bprm->mm) { |
1555 | acct_arg_size(bprm, 0); |
1556 | mmput(bprm->mm); |
1557 | } |
1558 | |
1559 | out_file: |
1560 | if (bprm->file) { |
1561 | allow_write_access(bprm->file); |
1562 | fput(bprm->file); |
1563 | } |
1564 | |
1565 | out_unmark: |
1566 | if (clear_in_exec) |
1567 | current->fs->in_exec = 0; |
1568 | current->in_execve = 0; |
1569 | |
1570 | out_free: |
1571 | free_bprm(bprm); |
1572 | |
1573 | out_files: |
1574 | if (displaced) |
1575 | reset_files_struct(displaced); |
1576 | out_ret: |
1577 | return retval; |
1578 | } |
1579 | |
1580 | int do_execve(const char *filename, |
1581 | const char __user *const __user *__argv, |
1582 | const char __user *const __user *__envp, |
1583 | struct pt_regs *regs) |
1584 | { |
1585 | struct user_arg_ptr argv = { .ptr.native = __argv }; |
1586 | struct user_arg_ptr envp = { .ptr.native = __envp }; |
1587 | return do_execve_common(filename, argv, envp, regs); |
1588 | } |
1589 | |
1590 | #ifdef CONFIG_COMPAT |
1591 | int compat_do_execve(char *filename, |
1592 | compat_uptr_t __user *__argv, |
1593 | compat_uptr_t __user *__envp, |
1594 | struct pt_regs *regs) |
1595 | { |
1596 | struct user_arg_ptr argv = { |
1597 | .is_compat = true, |
1598 | .ptr.compat = __argv, |
1599 | }; |
1600 | struct user_arg_ptr envp = { |
1601 | .is_compat = true, |
1602 | .ptr.compat = __envp, |
1603 | }; |
1604 | return do_execve_common(filename, argv, envp, regs); |
1605 | } |
1606 | #endif |
1607 | |
1608 | void set_binfmt(struct linux_binfmt *new) |
1609 | { |
1610 | struct mm_struct *mm = current->mm; |
1611 | |
1612 | if (mm->binfmt) |
1613 | module_put(mm->binfmt->module); |
1614 | |
1615 | mm->binfmt = new; |
1616 | if (new) |
1617 | __module_get(new->module); |
1618 | } |
1619 | |
1620 | EXPORT_SYMBOL(set_binfmt); |
1621 | |
1622 | static int expand_corename(struct core_name *cn) |
1623 | { |
1624 | char *old_corename = cn->corename; |
1625 | |
1626 | cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count); |
1627 | cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL); |
1628 | |
1629 | if (!cn->corename) { |
1630 | kfree(old_corename); |
1631 | return -ENOMEM; |
1632 | } |
1633 | |
1634 | return 0; |
1635 | } |
1636 | |
1637 | static int cn_printf(struct core_name *cn, const char *fmt, ...) |
1638 | { |
1639 | char *cur; |
1640 | int need; |
1641 | int ret; |
1642 | va_list arg; |
1643 | |
1644 | va_start(arg, fmt); |
1645 | need = vsnprintf(NULL, 0, fmt, arg); |
1646 | va_end(arg); |
1647 | |
1648 | if (likely(need < cn->size - cn->used - 1)) |
1649 | goto out_printf; |
1650 | |
1651 | ret = expand_corename(cn); |
1652 | if (ret) |
1653 | goto expand_fail; |
1654 | |
1655 | out_printf: |
1656 | cur = cn->corename + cn->used; |
1657 | va_start(arg, fmt); |
1658 | vsnprintf(cur, need + 1, fmt, arg); |
1659 | va_end(arg); |
1660 | cn->used += need; |
1661 | return 0; |
1662 | |
1663 | expand_fail: |
1664 | return ret; |
1665 | } |
1666 | |
1667 | static void cn_escape(char *str) |
1668 | { |
1669 | for (; *str; str++) |
1670 | if (*str == '/') |
1671 | *str = '!'; |
1672 | } |
1673 | |
1674 | static int cn_print_exe_file(struct core_name *cn) |
1675 | { |
1676 | struct file *exe_file; |
1677 | char *pathbuf, *path; |
1678 | int ret; |
1679 | |
1680 | exe_file = get_mm_exe_file(current->mm); |
1681 | if (!exe_file) { |
1682 | char *commstart = cn->corename + cn->used; |
1683 | ret = cn_printf(cn, "%s (path unknown)", current->comm); |
1684 | cn_escape(commstart); |
1685 | return ret; |
1686 | } |
1687 | |
1688 | pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY); |
1689 | if (!pathbuf) { |
1690 | ret = -ENOMEM; |
1691 | goto put_exe_file; |
1692 | } |
1693 | |
1694 | path = d_path(&exe_file->f_path, pathbuf, PATH_MAX); |
1695 | if (IS_ERR(path)) { |
1696 | ret = PTR_ERR(path); |
1697 | goto free_buf; |
1698 | } |
1699 | |
1700 | cn_escape(path); |
1701 | |
1702 | ret = cn_printf(cn, "%s", path); |
1703 | |
1704 | free_buf: |
1705 | kfree(pathbuf); |
1706 | put_exe_file: |
1707 | fput(exe_file); |
1708 | return ret; |
1709 | } |
1710 | |
1711 | /* format_corename will inspect the pattern parameter, and output a |
1712 | * name into corename, which must have space for at least |
1713 | * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator. |
1714 | */ |
1715 | static int format_corename(struct core_name *cn, long signr) |
1716 | { |
1717 | const struct cred *cred = current_cred(); |
1718 | const char *pat_ptr = core_pattern; |
1719 | int ispipe = (*pat_ptr == '|'); |
1720 | int pid_in_pattern = 0; |
1721 | int err = 0; |
1722 | |
1723 | cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count); |
1724 | cn->corename = kmalloc(cn->size, GFP_KERNEL); |
1725 | cn->used = 0; |
1726 | |
1727 | if (!cn->corename) |
1728 | return -ENOMEM; |
1729 | |
1730 | /* Repeat as long as we have more pattern to process and more output |
1731 | space */ |
1732 | while (*pat_ptr) { |
1733 | if (*pat_ptr != '%') { |
1734 | if (*pat_ptr == 0) |
1735 | goto out; |
1736 | err = cn_printf(cn, "%c", *pat_ptr++); |
1737 | } else { |
1738 | switch (*++pat_ptr) { |
1739 | /* single % at the end, drop that */ |
1740 | case 0: |
1741 | goto out; |
1742 | /* Double percent, output one percent */ |
1743 | case '%': |
1744 | err = cn_printf(cn, "%c", '%'); |
1745 | break; |
1746 | /* pid */ |
1747 | case 'p': |
1748 | pid_in_pattern = 1; |
1749 | err = cn_printf(cn, "%d", |
1750 | task_tgid_vnr(current)); |
1751 | break; |
1752 | /* uid */ |
1753 | case 'u': |
1754 | err = cn_printf(cn, "%d", cred->uid); |
1755 | break; |
1756 | /* gid */ |
1757 | case 'g': |
1758 | err = cn_printf(cn, "%d", cred->gid); |
1759 | break; |
1760 | /* signal that caused the coredump */ |
1761 | case 's': |
1762 | err = cn_printf(cn, "%ld", signr); |
1763 | break; |
1764 | /* UNIX time of coredump */ |
1765 | case 't': { |
1766 | struct timeval tv; |
1767 | do_gettimeofday(&tv); |
1768 | err = cn_printf(cn, "%lu", tv.tv_sec); |
1769 | break; |
1770 | } |
1771 | /* hostname */ |
1772 | case 'h': { |
1773 | char *namestart = cn->corename + cn->used; |
1774 | down_read(&uts_sem); |
1775 | err = cn_printf(cn, "%s", |
1776 | utsname()->nodename); |
1777 | up_read(&uts_sem); |
1778 | cn_escape(namestart); |
1779 | break; |
1780 | } |
1781 | /* executable */ |
1782 | case 'e': { |
1783 | char *commstart = cn->corename + cn->used; |
1784 | err = cn_printf(cn, "%s", current->comm); |
1785 | cn_escape(commstart); |
1786 | break; |
1787 | } |
1788 | case 'E': |
1789 | err = cn_print_exe_file(cn); |
1790 | break; |
1791 | /* core limit size */ |
1792 | case 'c': |
1793 | err = cn_printf(cn, "%lu", |
1794 | rlimit(RLIMIT_CORE)); |
1795 | break; |
1796 | default: |
1797 | break; |
1798 | } |
1799 | ++pat_ptr; |
1800 | } |
1801 | |
1802 | if (err) |
1803 | return err; |
1804 | } |
1805 | |
1806 | /* Backward compatibility with core_uses_pid: |
1807 | * |
1808 | * If core_pattern does not include a %p (as is the default) |
1809 | * and core_uses_pid is set, then .%pid will be appended to |
1810 | * the filename. Do not do this for piped commands. */ |
1811 | if (!ispipe && !pid_in_pattern && core_uses_pid) { |
1812 | err = cn_printf(cn, ".%d", task_tgid_vnr(current)); |
1813 | if (err) |
1814 | return err; |
1815 | } |
1816 | out: |
1817 | return ispipe; |
1818 | } |
1819 | |
1820 | static int zap_process(struct task_struct *start, int exit_code) |
1821 | { |
1822 | struct task_struct *t; |
1823 | int nr = 0; |
1824 | |
1825 | start->signal->flags = SIGNAL_GROUP_EXIT; |
1826 | start->signal->group_exit_code = exit_code; |
1827 | start->signal->group_stop_count = 0; |
1828 | |
1829 | t = start; |
1830 | do { |
1831 | task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); |
1832 | if (t != current && t->mm) { |
1833 | sigaddset(&t->pending.signal, SIGKILL); |
1834 | signal_wake_up(t, 1); |
1835 | nr++; |
1836 | } |
1837 | } while_each_thread(start, t); |
1838 | |
1839 | return nr; |
1840 | } |
1841 | |
1842 | static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm, |
1843 | struct core_state *core_state, int exit_code) |
1844 | { |
1845 | struct task_struct *g, *p; |
1846 | unsigned long flags; |
1847 | int nr = -EAGAIN; |
1848 | |
1849 | spin_lock_irq(&tsk->sighand->siglock); |
1850 | if (!signal_group_exit(tsk->signal)) { |
1851 | mm->core_state = core_state; |
1852 | nr = zap_process(tsk, exit_code); |
1853 | } |
1854 | spin_unlock_irq(&tsk->sighand->siglock); |
1855 | if (unlikely(nr < 0)) |
1856 | return nr; |
1857 | |
1858 | if (atomic_read(&mm->mm_users) == nr + 1) |
1859 | goto done; |
1860 | /* |
1861 | * We should find and kill all tasks which use this mm, and we should |
1862 | * count them correctly into ->nr_threads. We don't take tasklist |
1863 | * lock, but this is safe wrt: |
1864 | * |
1865 | * fork: |
1866 | * None of sub-threads can fork after zap_process(leader). All |
1867 | * processes which were created before this point should be |
1868 | * visible to zap_threads() because copy_process() adds the new |
1869 | * process to the tail of init_task.tasks list, and lock/unlock |
1870 | * of ->siglock provides a memory barrier. |
1871 | * |
1872 | * do_exit: |
1873 | * The caller holds mm->mmap_sem. This means that the task which |
1874 | * uses this mm can't pass exit_mm(), so it can't exit or clear |
1875 | * its ->mm. |
1876 | * |
1877 | * de_thread: |
1878 | * It does list_replace_rcu(&leader->tasks, ¤t->tasks), |
1879 | * we must see either old or new leader, this does not matter. |
1880 | * However, it can change p->sighand, so lock_task_sighand(p) |
1881 | * must be used. Since p->mm != NULL and we hold ->mmap_sem |
1882 | * it can't fail. |
1883 | * |
1884 | * Note also that "g" can be the old leader with ->mm == NULL |
1885 | * and already unhashed and thus removed from ->thread_group. |
1886 | * This is OK, __unhash_process()->list_del_rcu() does not |
1887 | * clear the ->next pointer, we will find the new leader via |
1888 | * next_thread(). |
1889 | */ |
1890 | rcu_read_lock(); |
1891 | for_each_process(g) { |
1892 | if (g == tsk->group_leader) |
1893 | continue; |
1894 | if (g->flags & PF_KTHREAD) |
1895 | continue; |
1896 | p = g; |
1897 | do { |
1898 | if (p->mm) { |
1899 | if (unlikely(p->mm == mm)) { |
1900 | lock_task_sighand(p, &flags); |
1901 | nr += zap_process(p, exit_code); |
1902 | unlock_task_sighand(p, &flags); |
1903 | } |
1904 | break; |
1905 | } |
1906 | } while_each_thread(g, p); |
1907 | } |
1908 | rcu_read_unlock(); |
1909 | done: |
1910 | atomic_set(&core_state->nr_threads, nr); |
1911 | return nr; |
1912 | } |
1913 | |
1914 | static int coredump_wait(int exit_code, struct core_state *core_state) |
1915 | { |
1916 | struct task_struct *tsk = current; |
1917 | struct mm_struct *mm = tsk->mm; |
1918 | int core_waiters = -EBUSY; |
1919 | |
1920 | init_completion(&core_state->startup); |
1921 | core_state->dumper.task = tsk; |
1922 | core_state->dumper.next = NULL; |
1923 | |
1924 | down_write(&mm->mmap_sem); |
1925 | if (!mm->core_state) |
1926 | core_waiters = zap_threads(tsk, mm, core_state, exit_code); |
1927 | up_write(&mm->mmap_sem); |
1928 | |
1929 | if (core_waiters > 0) |
1930 | wait_for_completion(&core_state->startup); |
1931 | |
1932 | return core_waiters; |
1933 | } |
1934 | |
1935 | static void coredump_finish(struct mm_struct *mm) |
1936 | { |
1937 | struct core_thread *curr, *next; |
1938 | struct task_struct *task; |
1939 | |
1940 | next = mm->core_state->dumper.next; |
1941 | while ((curr = next) != NULL) { |
1942 | next = curr->next; |
1943 | task = curr->task; |
1944 | /* |
1945 | * see exit_mm(), curr->task must not see |
1946 | * ->task == NULL before we read ->next. |
1947 | */ |
1948 | smp_mb(); |
1949 | curr->task = NULL; |
1950 | wake_up_process(task); |
1951 | } |
1952 | |
1953 | mm->core_state = NULL; |
1954 | } |
1955 | |
1956 | /* |
1957 | * set_dumpable converts traditional three-value dumpable to two flags and |
1958 | * stores them into mm->flags. It modifies lower two bits of mm->flags, but |
1959 | * these bits are not changed atomically. So get_dumpable can observe the |
1960 | * intermediate state. To avoid doing unexpected behavior, get get_dumpable |
1961 | * return either old dumpable or new one by paying attention to the order of |
1962 | * modifying the bits. |
1963 | * |
1964 | * dumpable | mm->flags (binary) |
1965 | * old new | initial interim final |
1966 | * ---------+----------------------- |
1967 | * 0 1 | 00 01 01 |
1968 | * 0 2 | 00 10(*) 11 |
1969 | * 1 0 | 01 00 00 |
1970 | * 1 2 | 01 11 11 |
1971 | * 2 0 | 11 10(*) 00 |
1972 | * 2 1 | 11 11 01 |
1973 | * |
1974 | * (*) get_dumpable regards interim value of 10 as 11. |
1975 | */ |
1976 | void set_dumpable(struct mm_struct *mm, int value) |
1977 | { |
1978 | switch (value) { |
1979 | case 0: |
1980 | clear_bit(MMF_DUMPABLE, &mm->flags); |
1981 | smp_wmb(); |
1982 | clear_bit(MMF_DUMP_SECURELY, &mm->flags); |
1983 | break; |
1984 | case 1: |
1985 | set_bit(MMF_DUMPABLE, &mm->flags); |
1986 | smp_wmb(); |
1987 | clear_bit(MMF_DUMP_SECURELY, &mm->flags); |
1988 | break; |
1989 | case 2: |
1990 | set_bit(MMF_DUMP_SECURELY, &mm->flags); |
1991 | smp_wmb(); |
1992 | set_bit(MMF_DUMPABLE, &mm->flags); |
1993 | break; |
1994 | } |
1995 | } |
1996 | |
1997 | static int __get_dumpable(unsigned long mm_flags) |
1998 | { |
1999 | int ret; |
2000 | |
2001 | ret = mm_flags & MMF_DUMPABLE_MASK; |
2002 | return (ret >= 2) ? 2 : ret; |
2003 | } |
2004 | |
2005 | int get_dumpable(struct mm_struct *mm) |
2006 | { |
2007 | return __get_dumpable(mm->flags); |
2008 | } |
2009 | |
2010 | static void wait_for_dump_helpers(struct file *file) |
2011 | { |
2012 | struct pipe_inode_info *pipe; |
2013 | |
2014 | pipe = file->f_path.dentry->d_inode->i_pipe; |
2015 | |
2016 | pipe_lock(pipe); |
2017 | pipe->readers++; |
2018 | pipe->writers--; |
2019 | |
2020 | while ((pipe->readers > 1) && (!signal_pending(current))) { |
2021 | wake_up_interruptible_sync(&pipe->wait); |
2022 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
2023 | pipe_wait(pipe); |
2024 | } |
2025 | |
2026 | pipe->readers--; |
2027 | pipe->writers++; |
2028 | pipe_unlock(pipe); |
2029 | |
2030 | } |
2031 | |
2032 | |
2033 | /* |
2034 | * umh_pipe_setup |
2035 | * helper function to customize the process used |
2036 | * to collect the core in userspace. Specifically |
2037 | * it sets up a pipe and installs it as fd 0 (stdin) |
2038 | * for the process. Returns 0 on success, or |
2039 | * PTR_ERR on failure. |
2040 | * Note that it also sets the core limit to 1. This |
2041 | * is a special value that we use to trap recursive |
2042 | * core dumps |
2043 | */ |
2044 | static int umh_pipe_setup(struct subprocess_info *info, struct cred *new) |
2045 | { |
2046 | struct file *rp, *wp; |
2047 | struct fdtable *fdt; |
2048 | struct coredump_params *cp = (struct coredump_params *)info->data; |
2049 | struct files_struct *cf = current->files; |
2050 | |
2051 | wp = create_write_pipe(0); |
2052 | if (IS_ERR(wp)) |
2053 | return PTR_ERR(wp); |
2054 | |
2055 | rp = create_read_pipe(wp, 0); |
2056 | if (IS_ERR(rp)) { |
2057 | free_write_pipe(wp); |
2058 | return PTR_ERR(rp); |
2059 | } |
2060 | |
2061 | cp->file = wp; |
2062 | |
2063 | sys_close(0); |
2064 | fd_install(0, rp); |
2065 | spin_lock(&cf->file_lock); |
2066 | fdt = files_fdtable(cf); |
2067 | FD_SET(0, fdt->open_fds); |
2068 | FD_CLR(0, fdt->close_on_exec); |
2069 | spin_unlock(&cf->file_lock); |
2070 | |
2071 | /* and disallow core files too */ |
2072 | current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1}; |
2073 | |
2074 | return 0; |
2075 | } |
2076 | |
2077 | void do_coredump(long signr, int exit_code, struct pt_regs *regs) |
2078 | { |
2079 | struct core_state core_state; |
2080 | struct core_name cn; |
2081 | struct mm_struct *mm = current->mm; |
2082 | struct linux_binfmt * binfmt; |
2083 | const struct cred *old_cred; |
2084 | struct cred *cred; |
2085 | int retval = 0; |
2086 | int flag = 0; |
2087 | int ispipe; |
2088 | static atomic_t core_dump_count = ATOMIC_INIT(0); |
2089 | struct coredump_params cprm = { |
2090 | .signr = signr, |
2091 | .regs = regs, |
2092 | .limit = rlimit(RLIMIT_CORE), |
2093 | /* |
2094 | * We must use the same mm->flags while dumping core to avoid |
2095 | * inconsistency of bit flags, since this flag is not protected |
2096 | * by any locks. |
2097 | */ |
2098 | .mm_flags = mm->flags, |
2099 | }; |
2100 | |
2101 | audit_core_dumps(signr); |
2102 | |
2103 | binfmt = mm->binfmt; |
2104 | if (!binfmt || !binfmt->core_dump) |
2105 | goto fail; |
2106 | if (!__get_dumpable(cprm.mm_flags)) |
2107 | goto fail; |
2108 | |
2109 | cred = prepare_creds(); |
2110 | if (!cred) |
2111 | goto fail; |
2112 | /* |
2113 | * We cannot trust fsuid as being the "true" uid of the |
2114 | * process nor do we know its entire history. We only know it |
2115 | * was tainted so we dump it as root in mode 2. |
2116 | */ |
2117 | if (__get_dumpable(cprm.mm_flags) == 2) { |
2118 | /* Setuid core dump mode */ |
2119 | flag = O_EXCL; /* Stop rewrite attacks */ |
2120 | cred->fsuid = 0; /* Dump root private */ |
2121 | } |
2122 | |
2123 | retval = coredump_wait(exit_code, &core_state); |
2124 | if (retval < 0) |
2125 | goto fail_creds; |
2126 | |
2127 | old_cred = override_creds(cred); |
2128 | |
2129 | /* |
2130 | * Clear any false indication of pending signals that might |
2131 | * be seen by the filesystem code called to write the core file. |
2132 | */ |
2133 | clear_thread_flag(TIF_SIGPENDING); |
2134 | |
2135 | ispipe = format_corename(&cn, signr); |
2136 | |
2137 | if (ispipe) { |
2138 | int dump_count; |
2139 | char **helper_argv; |
2140 | |
2141 | if (ispipe < 0) { |
2142 | printk(KERN_WARNING "format_corename failed\n"); |
2143 | printk(KERN_WARNING "Aborting core\n"); |
2144 | goto fail_corename; |
2145 | } |
2146 | |
2147 | if (cprm.limit == 1) { |
2148 | /* |
2149 | * Normally core limits are irrelevant to pipes, since |
2150 | * we're not writing to the file system, but we use |
2151 | * cprm.limit of 1 here as a speacial value. Any |
2152 | * non-1 limit gets set to RLIM_INFINITY below, but |
2153 | * a limit of 0 skips the dump. This is a consistent |
2154 | * way to catch recursive crashes. We can still crash |
2155 | * if the core_pattern binary sets RLIM_CORE = !1 |
2156 | * but it runs as root, and can do lots of stupid things |
2157 | * Note that we use task_tgid_vnr here to grab the pid |
2158 | * of the process group leader. That way we get the |
2159 | * right pid if a thread in a multi-threaded |
2160 | * core_pattern process dies. |
2161 | */ |
2162 | printk(KERN_WARNING |
2163 | "Process %d(%s) has RLIMIT_CORE set to 1\n", |
2164 | task_tgid_vnr(current), current->comm); |
2165 | printk(KERN_WARNING "Aborting core\n"); |
2166 | goto fail_unlock; |
2167 | } |
2168 | cprm.limit = RLIM_INFINITY; |
2169 | |
2170 | dump_count = atomic_inc_return(&core_dump_count); |
2171 | if (core_pipe_limit && (core_pipe_limit < dump_count)) { |
2172 | printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n", |
2173 | task_tgid_vnr(current), current->comm); |
2174 | printk(KERN_WARNING "Skipping core dump\n"); |
2175 | goto fail_dropcount; |
2176 | } |
2177 | |
2178 | helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL); |
2179 | if (!helper_argv) { |
2180 | printk(KERN_WARNING "%s failed to allocate memory\n", |
2181 | __func__); |
2182 | goto fail_dropcount; |
2183 | } |
2184 | |
2185 | retval = call_usermodehelper_fns(helper_argv[0], helper_argv, |
2186 | NULL, UMH_WAIT_EXEC, umh_pipe_setup, |
2187 | NULL, &cprm); |
2188 | argv_free(helper_argv); |
2189 | if (retval) { |
2190 | printk(KERN_INFO "Core dump to %s pipe failed\n", |
2191 | cn.corename); |
2192 | goto close_fail; |
2193 | } |
2194 | } else { |
2195 | struct inode *inode; |
2196 | |
2197 | if (cprm.limit < binfmt->min_coredump) |
2198 | goto fail_unlock; |
2199 | |
2200 | cprm.file = filp_open(cn.corename, |
2201 | O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, |
2202 | 0600); |
2203 | if (IS_ERR(cprm.file)) |
2204 | goto fail_unlock; |
2205 | |
2206 | inode = cprm.file->f_path.dentry->d_inode; |
2207 | if (inode->i_nlink > 1) |
2208 | goto close_fail; |
2209 | if (d_unhashed(cprm.file->f_path.dentry)) |
2210 | goto close_fail; |
2211 | /* |
2212 | * AK: actually i see no reason to not allow this for named |
2213 | * pipes etc, but keep the previous behaviour for now. |
2214 | */ |
2215 | if (!S_ISREG(inode->i_mode)) |
2216 | goto close_fail; |
2217 | /* |
2218 | * Dont allow local users get cute and trick others to coredump |
2219 | * into their pre-created files. |
2220 | */ |
2221 | if (inode->i_uid != current_fsuid()) |
2222 | goto close_fail; |
2223 | if (!cprm.file->f_op || !cprm.file->f_op->write) |
2224 | goto close_fail; |
2225 | if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file)) |
2226 | goto close_fail; |
2227 | } |
2228 | |
2229 | retval = binfmt->core_dump(&cprm); |
2230 | if (retval) |
2231 | current->signal->group_exit_code |= 0x80; |
2232 | |
2233 | if (ispipe && core_pipe_limit) |
2234 | wait_for_dump_helpers(cprm.file); |
2235 | close_fail: |
2236 | if (cprm.file) |
2237 | filp_close(cprm.file, NULL); |
2238 | fail_dropcount: |
2239 | if (ispipe) |
2240 | atomic_dec(&core_dump_count); |
2241 | fail_unlock: |
2242 | kfree(cn.corename); |
2243 | fail_corename: |
2244 | coredump_finish(mm); |
2245 | revert_creds(old_cred); |
2246 | fail_creds: |
2247 | put_cred(cred); |
2248 | fail: |
2249 | return; |
2250 | } |
2251 | |
2252 | /* |
2253 | * Core dumping helper functions. These are the only things you should |
2254 | * do on a core-file: use only these functions to write out all the |
2255 | * necessary info. |
2256 | */ |
2257 | int dump_write(struct file *file, const void *addr, int nr) |
2258 | { |
2259 | return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr; |
2260 | } |
2261 | EXPORT_SYMBOL(dump_write); |
2262 | |
2263 | int dump_seek(struct file *file, loff_t off) |
2264 | { |
2265 | int ret = 1; |
2266 | |
2267 | if (file->f_op->llseek && file->f_op->llseek != no_llseek) { |
2268 | if (file->f_op->llseek(file, off, SEEK_CUR) < 0) |
2269 | return 0; |
2270 | } else { |
2271 | char *buf = (char *)get_zeroed_page(GFP_KERNEL); |
2272 | |
2273 | if (!buf) |
2274 | return 0; |
2275 | while (off > 0) { |
2276 | unsigned long n = off; |
2277 | |
2278 | if (n > PAGE_SIZE) |
2279 | n = PAGE_SIZE; |
2280 | if (!dump_write(file, buf, n)) { |
2281 | ret = 0; |
2282 | break; |
2283 | } |
2284 | off -= n; |
2285 | } |
2286 | free_page((unsigned long)buf); |
2287 | } |
2288 | return ret; |
2289 | } |
2290 | EXPORT_SYMBOL(dump_seek); |
2291 |
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