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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 | #include <asm/exec.h> |
63 | |
64 | #include <trace/events/task.h> |
65 | #include "internal.h" |
66 | |
67 | #include <trace/events/sched.h> |
68 | |
69 | int core_uses_pid; |
70 | char core_pattern[CORENAME_MAX_SIZE] = "core"; |
71 | unsigned int core_pipe_limit; |
72 | int suid_dumpable = 0; |
73 | |
74 | struct core_name { |
75 | char *corename; |
76 | int used, size; |
77 | }; |
78 | static atomic_t call_count = ATOMIC_INIT(1); |
79 | |
80 | /* The maximal length of core_pattern is also specified in sysctl.c */ |
81 | |
82 | static LIST_HEAD(formats); |
83 | static DEFINE_RWLOCK(binfmt_lock); |
84 | |
85 | void __register_binfmt(struct linux_binfmt * fmt, int insert) |
86 | { |
87 | BUG_ON(!fmt); |
88 | write_lock(&binfmt_lock); |
89 | insert ? list_add(&fmt->lh, &formats) : |
90 | list_add_tail(&fmt->lh, &formats); |
91 | write_unlock(&binfmt_lock); |
92 | } |
93 | |
94 | EXPORT_SYMBOL(__register_binfmt); |
95 | |
96 | void unregister_binfmt(struct linux_binfmt * fmt) |
97 | { |
98 | write_lock(&binfmt_lock); |
99 | list_del(&fmt->lh); |
100 | write_unlock(&binfmt_lock); |
101 | } |
102 | |
103 | EXPORT_SYMBOL(unregister_binfmt); |
104 | |
105 | static inline void put_binfmt(struct linux_binfmt * fmt) |
106 | { |
107 | module_put(fmt->module); |
108 | } |
109 | |
110 | /* |
111 | * Note that a shared library must be both readable and executable due to |
112 | * security reasons. |
113 | * |
114 | * Also note that we take the address to load from from the file itself. |
115 | */ |
116 | SYSCALL_DEFINE1(uselib, const char __user *, library) |
117 | { |
118 | struct file *file; |
119 | char *tmp = getname(library); |
120 | int error = PTR_ERR(tmp); |
121 | static const struct open_flags uselib_flags = { |
122 | .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, |
123 | .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN, |
124 | .intent = LOOKUP_OPEN |
125 | }; |
126 | |
127 | if (IS_ERR(tmp)) |
128 | goto out; |
129 | |
130 | file = do_filp_open(AT_FDCWD, tmp, &uselib_flags, LOOKUP_FOLLOW); |
131 | putname(tmp); |
132 | error = PTR_ERR(file); |
133 | if (IS_ERR(file)) |
134 | goto out; |
135 | |
136 | error = -EINVAL; |
137 | if (!S_ISREG(file->f_path.dentry->d_inode->i_mode)) |
138 | goto exit; |
139 | |
140 | error = -EACCES; |
141 | if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) |
142 | goto exit; |
143 | |
144 | fsnotify_open(file); |
145 | |
146 | error = -ENOEXEC; |
147 | if(file->f_op) { |
148 | struct linux_binfmt * fmt; |
149 | |
150 | read_lock(&binfmt_lock); |
151 | list_for_each_entry(fmt, &formats, lh) { |
152 | if (!fmt->load_shlib) |
153 | continue; |
154 | if (!try_module_get(fmt->module)) |
155 | continue; |
156 | read_unlock(&binfmt_lock); |
157 | error = fmt->load_shlib(file); |
158 | read_lock(&binfmt_lock); |
159 | put_binfmt(fmt); |
160 | if (error != -ENOEXEC) |
161 | break; |
162 | } |
163 | read_unlock(&binfmt_lock); |
164 | } |
165 | exit: |
166 | fput(file); |
167 | out: |
168 | return error; |
169 | } |
170 | |
171 | #ifdef CONFIG_MMU |
172 | /* |
173 | * The nascent bprm->mm is not visible until exec_mmap() but it can |
174 | * use a lot of memory, account these pages in current->mm temporary |
175 | * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we |
176 | * change the counter back via acct_arg_size(0). |
177 | */ |
178 | static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) |
179 | { |
180 | struct mm_struct *mm = current->mm; |
181 | long diff = (long)(pages - bprm->vma_pages); |
182 | |
183 | if (!mm || !diff) |
184 | return; |
185 | |
186 | bprm->vma_pages = pages; |
187 | add_mm_counter(mm, MM_ANONPAGES, diff); |
188 | } |
189 | |
190 | static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, |
191 | int write) |
192 | { |
193 | struct page *page; |
194 | int ret; |
195 | |
196 | #ifdef CONFIG_STACK_GROWSUP |
197 | if (write) { |
198 | ret = expand_downwards(bprm->vma, pos); |
199 | if (ret < 0) |
200 | return NULL; |
201 | } |
202 | #endif |
203 | ret = get_user_pages(current, bprm->mm, pos, |
204 | 1, write, 1, &page, NULL); |
205 | if (ret <= 0) |
206 | return NULL; |
207 | |
208 | if (write) { |
209 | unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start; |
210 | struct rlimit *rlim; |
211 | |
212 | acct_arg_size(bprm, size / PAGE_SIZE); |
213 | |
214 | /* |
215 | * We've historically supported up to 32 pages (ARG_MAX) |
216 | * of argument strings even with small stacks |
217 | */ |
218 | if (size <= ARG_MAX) |
219 | return page; |
220 | |
221 | /* |
222 | * Limit to 1/4-th the stack size for the argv+env strings. |
223 | * This ensures that: |
224 | * - the remaining binfmt code will not run out of stack space, |
225 | * - the program will have a reasonable amount of stack left |
226 | * to work from. |
227 | */ |
228 | rlim = current->signal->rlim; |
229 | if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) { |
230 | put_page(page); |
231 | return NULL; |
232 | } |
233 | } |
234 | |
235 | return page; |
236 | } |
237 | |
238 | static void put_arg_page(struct page *page) |
239 | { |
240 | put_page(page); |
241 | } |
242 | |
243 | static void free_arg_page(struct linux_binprm *bprm, int i) |
244 | { |
245 | } |
246 | |
247 | static void free_arg_pages(struct linux_binprm *bprm) |
248 | { |
249 | } |
250 | |
251 | static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, |
252 | struct page *page) |
253 | { |
254 | flush_cache_page(bprm->vma, pos, page_to_pfn(page)); |
255 | } |
256 | |
257 | static int __bprm_mm_init(struct linux_binprm *bprm) |
258 | { |
259 | int err; |
260 | struct vm_area_struct *vma = NULL; |
261 | struct mm_struct *mm = bprm->mm; |
262 | |
263 | bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); |
264 | if (!vma) |
265 | return -ENOMEM; |
266 | |
267 | down_write(&mm->mmap_sem); |
268 | vma->vm_mm = mm; |
269 | |
270 | /* |
271 | * Place the stack at the largest stack address the architecture |
272 | * supports. Later, we'll move this to an appropriate place. We don't |
273 | * use STACK_TOP because that can depend on attributes which aren't |
274 | * configured yet. |
275 | */ |
276 | BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP); |
277 | vma->vm_end = STACK_TOP_MAX; |
278 | vma->vm_start = vma->vm_end - PAGE_SIZE; |
279 | vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP; |
280 | vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); |
281 | INIT_LIST_HEAD(&vma->anon_vma_chain); |
282 | |
283 | err = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1); |
284 | if (err) |
285 | goto err; |
286 | |
287 | err = insert_vm_struct(mm, vma); |
288 | if (err) |
289 | goto err; |
290 | |
291 | mm->stack_vm = mm->total_vm = 1; |
292 | up_write(&mm->mmap_sem); |
293 | bprm->p = vma->vm_end - sizeof(void *); |
294 | return 0; |
295 | err: |
296 | up_write(&mm->mmap_sem); |
297 | bprm->vma = NULL; |
298 | kmem_cache_free(vm_area_cachep, vma); |
299 | return err; |
300 | } |
301 | |
302 | static bool valid_arg_len(struct linux_binprm *bprm, long len) |
303 | { |
304 | return len <= MAX_ARG_STRLEN; |
305 | } |
306 | |
307 | #else |
308 | |
309 | static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) |
310 | { |
311 | } |
312 | |
313 | static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, |
314 | int write) |
315 | { |
316 | struct page *page; |
317 | |
318 | page = bprm->page[pos / PAGE_SIZE]; |
319 | if (!page && write) { |
320 | page = alloc_page(GFP_HIGHUSER|__GFP_ZERO); |
321 | if (!page) |
322 | return NULL; |
323 | bprm->page[pos / PAGE_SIZE] = page; |
324 | } |
325 | |
326 | return page; |
327 | } |
328 | |
329 | static void put_arg_page(struct page *page) |
330 | { |
331 | } |
332 | |
333 | static void free_arg_page(struct linux_binprm *bprm, int i) |
334 | { |
335 | if (bprm->page[i]) { |
336 | __free_page(bprm->page[i]); |
337 | bprm->page[i] = NULL; |
338 | } |
339 | } |
340 | |
341 | static void free_arg_pages(struct linux_binprm *bprm) |
342 | { |
343 | int i; |
344 | |
345 | for (i = 0; i < MAX_ARG_PAGES; i++) |
346 | free_arg_page(bprm, i); |
347 | } |
348 | |
349 | static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, |
350 | struct page *page) |
351 | { |
352 | } |
353 | |
354 | static int __bprm_mm_init(struct linux_binprm *bprm) |
355 | { |
356 | bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *); |
357 | return 0; |
358 | } |
359 | |
360 | static bool valid_arg_len(struct linux_binprm *bprm, long len) |
361 | { |
362 | return len <= bprm->p; |
363 | } |
364 | |
365 | #endif /* CONFIG_MMU */ |
366 | |
367 | /* |
368 | * Create a new mm_struct and populate it with a temporary stack |
369 | * vm_area_struct. We don't have enough context at this point to set the stack |
370 | * flags, permissions, and offset, so we use temporary values. We'll update |
371 | * them later in setup_arg_pages(). |
372 | */ |
373 | int bprm_mm_init(struct linux_binprm *bprm) |
374 | { |
375 | int err; |
376 | struct mm_struct *mm = NULL; |
377 | |
378 | bprm->mm = mm = mm_alloc(); |
379 | err = -ENOMEM; |
380 | if (!mm) |
381 | goto err; |
382 | |
383 | err = init_new_context(current, mm); |
384 | if (err) |
385 | goto err; |
386 | |
387 | err = __bprm_mm_init(bprm); |
388 | if (err) |
389 | goto err; |
390 | |
391 | return 0; |
392 | |
393 | err: |
394 | if (mm) { |
395 | bprm->mm = NULL; |
396 | mmdrop(mm); |
397 | } |
398 | |
399 | return err; |
400 | } |
401 | |
402 | struct user_arg_ptr { |
403 | #ifdef CONFIG_COMPAT |
404 | bool is_compat; |
405 | #endif |
406 | union { |
407 | const char __user *const __user *native; |
408 | #ifdef CONFIG_COMPAT |
409 | compat_uptr_t __user *compat; |
410 | #endif |
411 | } ptr; |
412 | }; |
413 | |
414 | static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr) |
415 | { |
416 | const char __user *native; |
417 | |
418 | #ifdef CONFIG_COMPAT |
419 | if (unlikely(argv.is_compat)) { |
420 | compat_uptr_t compat; |
421 | |
422 | if (get_user(compat, argv.ptr.compat + nr)) |
423 | return ERR_PTR(-EFAULT); |
424 | |
425 | return compat_ptr(compat); |
426 | } |
427 | #endif |
428 | |
429 | if (get_user(native, argv.ptr.native + nr)) |
430 | return ERR_PTR(-EFAULT); |
431 | |
432 | return native; |
433 | } |
434 | |
435 | /* |
436 | * count() counts the number of strings in array ARGV. |
437 | */ |
438 | static int count(struct user_arg_ptr argv, int max) |
439 | { |
440 | int i = 0; |
441 | |
442 | if (argv.ptr.native != NULL) { |
443 | for (;;) { |
444 | const char __user *p = get_user_arg_ptr(argv, i); |
445 | |
446 | if (!p) |
447 | break; |
448 | |
449 | if (IS_ERR(p)) |
450 | return -EFAULT; |
451 | |
452 | if (i++ >= max) |
453 | return -E2BIG; |
454 | |
455 | if (fatal_signal_pending(current)) |
456 | return -ERESTARTNOHAND; |
457 | cond_resched(); |
458 | } |
459 | } |
460 | return i; |
461 | } |
462 | |
463 | /* |
464 | * 'copy_strings()' copies argument/environment strings from the old |
465 | * processes's memory to the new process's stack. The call to get_user_pages() |
466 | * ensures the destination page is created and not swapped out. |
467 | */ |
468 | static int copy_strings(int argc, struct user_arg_ptr argv, |
469 | struct linux_binprm *bprm) |
470 | { |
471 | struct page *kmapped_page = NULL; |
472 | char *kaddr = NULL; |
473 | unsigned long kpos = 0; |
474 | int ret; |
475 | |
476 | while (argc-- > 0) { |
477 | const char __user *str; |
478 | int len; |
479 | unsigned long pos; |
480 | |
481 | ret = -EFAULT; |
482 | str = get_user_arg_ptr(argv, argc); |
483 | if (IS_ERR(str)) |
484 | goto out; |
485 | |
486 | len = strnlen_user(str, MAX_ARG_STRLEN); |
487 | if (!len) |
488 | goto out; |
489 | |
490 | ret = -E2BIG; |
491 | if (!valid_arg_len(bprm, len)) |
492 | goto out; |
493 | |
494 | /* We're going to work our way backwords. */ |
495 | pos = bprm->p; |
496 | str += len; |
497 | bprm->p -= len; |
498 | |
499 | while (len > 0) { |
500 | int offset, bytes_to_copy; |
501 | |
502 | if (fatal_signal_pending(current)) { |
503 | ret = -ERESTARTNOHAND; |
504 | goto out; |
505 | } |
506 | cond_resched(); |
507 | |
508 | offset = pos % PAGE_SIZE; |
509 | if (offset == 0) |
510 | offset = PAGE_SIZE; |
511 | |
512 | bytes_to_copy = offset; |
513 | if (bytes_to_copy > len) |
514 | bytes_to_copy = len; |
515 | |
516 | offset -= bytes_to_copy; |
517 | pos -= bytes_to_copy; |
518 | str -= bytes_to_copy; |
519 | len -= bytes_to_copy; |
520 | |
521 | if (!kmapped_page || kpos != (pos & PAGE_MASK)) { |
522 | struct page *page; |
523 | |
524 | page = get_arg_page(bprm, pos, 1); |
525 | if (!page) { |
526 | ret = -E2BIG; |
527 | goto out; |
528 | } |
529 | |
530 | if (kmapped_page) { |
531 | flush_kernel_dcache_page(kmapped_page); |
532 | kunmap(kmapped_page); |
533 | put_arg_page(kmapped_page); |
534 | } |
535 | kmapped_page = page; |
536 | kaddr = kmap(kmapped_page); |
537 | kpos = pos & PAGE_MASK; |
538 | flush_arg_page(bprm, kpos, kmapped_page); |
539 | } |
540 | if (copy_from_user(kaddr+offset, str, bytes_to_copy)) { |
541 | ret = -EFAULT; |
542 | goto out; |
543 | } |
544 | } |
545 | } |
546 | ret = 0; |
547 | out: |
548 | if (kmapped_page) { |
549 | flush_kernel_dcache_page(kmapped_page); |
550 | kunmap(kmapped_page); |
551 | put_arg_page(kmapped_page); |
552 | } |
553 | return ret; |
554 | } |
555 | |
556 | /* |
557 | * Like copy_strings, but get argv and its values from kernel memory. |
558 | */ |
559 | int copy_strings_kernel(int argc, const char *const *__argv, |
560 | struct linux_binprm *bprm) |
561 | { |
562 | int r; |
563 | mm_segment_t oldfs = get_fs(); |
564 | struct user_arg_ptr argv = { |
565 | .ptr.native = (const char __user *const __user *)__argv, |
566 | }; |
567 | |
568 | set_fs(KERNEL_DS); |
569 | r = copy_strings(argc, argv, bprm); |
570 | set_fs(oldfs); |
571 | |
572 | return r; |
573 | } |
574 | EXPORT_SYMBOL(copy_strings_kernel); |
575 | |
576 | #ifdef CONFIG_MMU |
577 | |
578 | /* |
579 | * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once |
580 | * the binfmt code determines where the new stack should reside, we shift it to |
581 | * its final location. The process proceeds as follows: |
582 | * |
583 | * 1) Use shift to calculate the new vma endpoints. |
584 | * 2) Extend vma to cover both the old and new ranges. This ensures the |
585 | * arguments passed to subsequent functions are consistent. |
586 | * 3) Move vma's page tables to the new range. |
587 | * 4) Free up any cleared pgd range. |
588 | * 5) Shrink the vma to cover only the new range. |
589 | */ |
590 | static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift) |
591 | { |
592 | struct mm_struct *mm = vma->vm_mm; |
593 | unsigned long old_start = vma->vm_start; |
594 | unsigned long old_end = vma->vm_end; |
595 | unsigned long length = old_end - old_start; |
596 | unsigned long new_start = old_start - shift; |
597 | unsigned long new_end = old_end - shift; |
598 | struct mmu_gather tlb; |
599 | |
600 | BUG_ON(new_start > new_end); |
601 | |
602 | /* |
603 | * ensure there are no vmas between where we want to go |
604 | * and where we are |
605 | */ |
606 | if (vma != find_vma(mm, new_start)) |
607 | return -EFAULT; |
608 | |
609 | /* |
610 | * cover the whole range: [new_start, old_end) |
611 | */ |
612 | if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL)) |
613 | return -ENOMEM; |
614 | |
615 | /* |
616 | * move the page tables downwards, on failure we rely on |
617 | * process cleanup to remove whatever mess we made. |
618 | */ |
619 | if (length != move_page_tables(vma, old_start, |
620 | vma, new_start, length)) |
621 | return -ENOMEM; |
622 | |
623 | lru_add_drain(); |
624 | tlb_gather_mmu(&tlb, mm, 0); |
625 | if (new_end > old_start) { |
626 | /* |
627 | * when the old and new regions overlap clear from new_end. |
628 | */ |
629 | free_pgd_range(&tlb, new_end, old_end, new_end, |
630 | vma->vm_next ? vma->vm_next->vm_start : 0); |
631 | } else { |
632 | /* |
633 | * otherwise, clean from old_start; this is done to not touch |
634 | * the address space in [new_end, old_start) some architectures |
635 | * have constraints on va-space that make this illegal (IA64) - |
636 | * for the others its just a little faster. |
637 | */ |
638 | free_pgd_range(&tlb, old_start, old_end, new_end, |
639 | vma->vm_next ? vma->vm_next->vm_start : 0); |
640 | } |
641 | tlb_finish_mmu(&tlb, new_end, old_end); |
642 | |
643 | /* |
644 | * Shrink the vma to just the new range. Always succeeds. |
645 | */ |
646 | vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL); |
647 | |
648 | return 0; |
649 | } |
650 | |
651 | /* |
652 | * Finalizes the stack vm_area_struct. The flags and permissions are updated, |
653 | * the stack is optionally relocated, and some extra space is added. |
654 | */ |
655 | int setup_arg_pages(struct linux_binprm *bprm, |
656 | unsigned long stack_top, |
657 | int executable_stack) |
658 | { |
659 | unsigned long ret; |
660 | unsigned long stack_shift; |
661 | struct mm_struct *mm = current->mm; |
662 | struct vm_area_struct *vma = bprm->vma; |
663 | struct vm_area_struct *prev = NULL; |
664 | unsigned long vm_flags; |
665 | unsigned long stack_base; |
666 | unsigned long stack_size; |
667 | unsigned long stack_expand; |
668 | unsigned long rlim_stack; |
669 | |
670 | #ifdef CONFIG_STACK_GROWSUP |
671 | /* Limit stack size to 1GB */ |
672 | stack_base = rlimit_max(RLIMIT_STACK); |
673 | if (stack_base > (1 << 30)) |
674 | stack_base = 1 << 30; |
675 | |
676 | /* Make sure we didn't let the argument array grow too large. */ |
677 | if (vma->vm_end - vma->vm_start > stack_base) |
678 | return -ENOMEM; |
679 | |
680 | stack_base = PAGE_ALIGN(stack_top - stack_base); |
681 | |
682 | stack_shift = vma->vm_start - stack_base; |
683 | mm->arg_start = bprm->p - stack_shift; |
684 | bprm->p = vma->vm_end - stack_shift; |
685 | #else |
686 | stack_top = arch_align_stack(stack_top); |
687 | stack_top = PAGE_ALIGN(stack_top); |
688 | |
689 | if (unlikely(stack_top < mmap_min_addr) || |
690 | unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr)) |
691 | return -ENOMEM; |
692 | |
693 | stack_shift = vma->vm_end - stack_top; |
694 | |
695 | bprm->p -= stack_shift; |
696 | mm->arg_start = bprm->p; |
697 | #endif |
698 | |
699 | if (bprm->loader) |
700 | bprm->loader -= stack_shift; |
701 | bprm->exec -= stack_shift; |
702 | |
703 | down_write(&mm->mmap_sem); |
704 | vm_flags = VM_STACK_FLAGS; |
705 | |
706 | /* |
707 | * Adjust stack execute permissions; explicitly enable for |
708 | * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone |
709 | * (arch default) otherwise. |
710 | */ |
711 | if (unlikely(executable_stack == EXSTACK_ENABLE_X)) |
712 | vm_flags |= VM_EXEC; |
713 | else if (executable_stack == EXSTACK_DISABLE_X) |
714 | vm_flags &= ~VM_EXEC; |
715 | vm_flags |= mm->def_flags; |
716 | vm_flags |= VM_STACK_INCOMPLETE_SETUP; |
717 | |
718 | ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end, |
719 | vm_flags); |
720 | if (ret) |
721 | goto out_unlock; |
722 | BUG_ON(prev != vma); |
723 | |
724 | /* Move stack pages down in memory. */ |
725 | if (stack_shift) { |
726 | ret = shift_arg_pages(vma, stack_shift); |
727 | if (ret) |
728 | goto out_unlock; |
729 | } |
730 | |
731 | /* mprotect_fixup is overkill to remove the temporary stack flags */ |
732 | vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP; |
733 | |
734 | stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */ |
735 | stack_size = vma->vm_end - vma->vm_start; |
736 | /* |
737 | * Align this down to a page boundary as expand_stack |
738 | * will align it up. |
739 | */ |
740 | rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK; |
741 | #ifdef CONFIG_STACK_GROWSUP |
742 | if (stack_size + stack_expand > rlim_stack) |
743 | stack_base = vma->vm_start + rlim_stack; |
744 | else |
745 | stack_base = vma->vm_end + stack_expand; |
746 | #else |
747 | if (stack_size + stack_expand > rlim_stack) |
748 | stack_base = vma->vm_end - rlim_stack; |
749 | else |
750 | stack_base = vma->vm_start - stack_expand; |
751 | #endif |
752 | current->mm->start_stack = bprm->p; |
753 | ret = expand_stack(vma, stack_base); |
754 | if (ret) |
755 | ret = -EFAULT; |
756 | |
757 | out_unlock: |
758 | up_write(&mm->mmap_sem); |
759 | return ret; |
760 | } |
761 | EXPORT_SYMBOL(setup_arg_pages); |
762 | |
763 | #endif /* CONFIG_MMU */ |
764 | |
765 | struct file *open_exec(const char *name) |
766 | { |
767 | struct file *file; |
768 | int err; |
769 | static const struct open_flags open_exec_flags = { |
770 | .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, |
771 | .acc_mode = MAY_EXEC | MAY_OPEN, |
772 | .intent = LOOKUP_OPEN |
773 | }; |
774 | |
775 | file = do_filp_open(AT_FDCWD, name, &open_exec_flags, LOOKUP_FOLLOW); |
776 | if (IS_ERR(file)) |
777 | goto out; |
778 | |
779 | err = -EACCES; |
780 | if (!S_ISREG(file->f_path.dentry->d_inode->i_mode)) |
781 | goto exit; |
782 | |
783 | if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) |
784 | goto exit; |
785 | |
786 | fsnotify_open(file); |
787 | |
788 | err = deny_write_access(file); |
789 | if (err) |
790 | goto exit; |
791 | |
792 | out: |
793 | return file; |
794 | |
795 | exit: |
796 | fput(file); |
797 | return ERR_PTR(err); |
798 | } |
799 | EXPORT_SYMBOL(open_exec); |
800 | |
801 | int kernel_read(struct file *file, loff_t offset, |
802 | char *addr, unsigned long count) |
803 | { |
804 | mm_segment_t old_fs; |
805 | loff_t pos = offset; |
806 | int result; |
807 | |
808 | old_fs = get_fs(); |
809 | set_fs(get_ds()); |
810 | /* The cast to a user pointer is valid due to the set_fs() */ |
811 | result = vfs_read(file, (void __user *)addr, count, &pos); |
812 | set_fs(old_fs); |
813 | return result; |
814 | } |
815 | |
816 | EXPORT_SYMBOL(kernel_read); |
817 | |
818 | static int exec_mmap(struct mm_struct *mm) |
819 | { |
820 | struct task_struct *tsk; |
821 | struct mm_struct * old_mm, *active_mm; |
822 | |
823 | /* Notify parent that we're no longer interested in the old VM */ |
824 | tsk = current; |
825 | old_mm = current->mm; |
826 | sync_mm_rss(old_mm); |
827 | mm_release(tsk, old_mm); |
828 | |
829 | if (old_mm) { |
830 | /* |
831 | * Make sure that if there is a core dump in progress |
832 | * for the old mm, we get out and die instead of going |
833 | * through with the exec. We must hold mmap_sem around |
834 | * checking core_state and changing tsk->mm. |
835 | */ |
836 | down_read(&old_mm->mmap_sem); |
837 | if (unlikely(old_mm->core_state)) { |
838 | up_read(&old_mm->mmap_sem); |
839 | return -EINTR; |
840 | } |
841 | } |
842 | task_lock(tsk); |
843 | active_mm = tsk->active_mm; |
844 | tsk->mm = mm; |
845 | tsk->active_mm = mm; |
846 | activate_mm(active_mm, mm); |
847 | task_unlock(tsk); |
848 | arch_pick_mmap_layout(mm); |
849 | if (old_mm) { |
850 | up_read(&old_mm->mmap_sem); |
851 | BUG_ON(active_mm != old_mm); |
852 | setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm); |
853 | mm_update_next_owner(old_mm); |
854 | mmput(old_mm); |
855 | return 0; |
856 | } |
857 | mmdrop(active_mm); |
858 | return 0; |
859 | } |
860 | |
861 | /* |
862 | * This function makes sure the current process has its own signal table, |
863 | * so that flush_signal_handlers can later reset the handlers without |
864 | * disturbing other processes. (Other processes might share the signal |
865 | * table via the CLONE_SIGHAND option to clone().) |
866 | */ |
867 | static int de_thread(struct task_struct *tsk) |
868 | { |
869 | struct signal_struct *sig = tsk->signal; |
870 | struct sighand_struct *oldsighand = tsk->sighand; |
871 | spinlock_t *lock = &oldsighand->siglock; |
872 | |
873 | if (thread_group_empty(tsk)) |
874 | goto no_thread_group; |
875 | |
876 | /* |
877 | * Kill all other threads in the thread group. |
878 | */ |
879 | spin_lock_irq(lock); |
880 | if (signal_group_exit(sig)) { |
881 | /* |
882 | * Another group action in progress, just |
883 | * return so that the signal is processed. |
884 | */ |
885 | spin_unlock_irq(lock); |
886 | return -EAGAIN; |
887 | } |
888 | |
889 | sig->group_exit_task = tsk; |
890 | sig->notify_count = zap_other_threads(tsk); |
891 | if (!thread_group_leader(tsk)) |
892 | sig->notify_count--; |
893 | |
894 | while (sig->notify_count) { |
895 | __set_current_state(TASK_UNINTERRUPTIBLE); |
896 | spin_unlock_irq(lock); |
897 | schedule(); |
898 | spin_lock_irq(lock); |
899 | } |
900 | spin_unlock_irq(lock); |
901 | |
902 | /* |
903 | * At this point all other threads have exited, all we have to |
904 | * do is to wait for the thread group leader to become inactive, |
905 | * and to assume its PID: |
906 | */ |
907 | if (!thread_group_leader(tsk)) { |
908 | struct task_struct *leader = tsk->group_leader; |
909 | |
910 | sig->notify_count = -1; /* for exit_notify() */ |
911 | for (;;) { |
912 | write_lock_irq(&tasklist_lock); |
913 | if (likely(leader->exit_state)) |
914 | break; |
915 | __set_current_state(TASK_UNINTERRUPTIBLE); |
916 | write_unlock_irq(&tasklist_lock); |
917 | schedule(); |
918 | } |
919 | |
920 | /* |
921 | * The only record we have of the real-time age of a |
922 | * process, regardless of execs it's done, is start_time. |
923 | * All the past CPU time is accumulated in signal_struct |
924 | * from sister threads now dead. But in this non-leader |
925 | * exec, nothing survives from the original leader thread, |
926 | * whose birth marks the true age of this process now. |
927 | * When we take on its identity by switching to its PID, we |
928 | * also take its birthdate (always earlier than our own). |
929 | */ |
930 | tsk->start_time = leader->start_time; |
931 | |
932 | BUG_ON(!same_thread_group(leader, tsk)); |
933 | BUG_ON(has_group_leader_pid(tsk)); |
934 | /* |
935 | * An exec() starts a new thread group with the |
936 | * TGID of the previous thread group. Rehash the |
937 | * two threads with a switched PID, and release |
938 | * the former thread group leader: |
939 | */ |
940 | |
941 | /* Become a process group leader with the old leader's pid. |
942 | * The old leader becomes a thread of the this thread group. |
943 | * Note: The old leader also uses this pid until release_task |
944 | * is called. Odd but simple and correct. |
945 | */ |
946 | detach_pid(tsk, PIDTYPE_PID); |
947 | tsk->pid = leader->pid; |
948 | attach_pid(tsk, PIDTYPE_PID, task_pid(leader)); |
949 | transfer_pid(leader, tsk, PIDTYPE_PGID); |
950 | transfer_pid(leader, tsk, PIDTYPE_SID); |
951 | |
952 | list_replace_rcu(&leader->tasks, &tsk->tasks); |
953 | list_replace_init(&leader->sibling, &tsk->sibling); |
954 | |
955 | tsk->group_leader = tsk; |
956 | leader->group_leader = tsk; |
957 | |
958 | tsk->exit_signal = SIGCHLD; |
959 | leader->exit_signal = -1; |
960 | |
961 | BUG_ON(leader->exit_state != EXIT_ZOMBIE); |
962 | leader->exit_state = EXIT_DEAD; |
963 | |
964 | /* |
965 | * We are going to release_task()->ptrace_unlink() silently, |
966 | * the tracer can sleep in do_wait(). EXIT_DEAD guarantees |
967 | * the tracer wont't block again waiting for this thread. |
968 | */ |
969 | if (unlikely(leader->ptrace)) |
970 | __wake_up_parent(leader, leader->parent); |
971 | write_unlock_irq(&tasklist_lock); |
972 | |
973 | release_task(leader); |
974 | } |
975 | |
976 | sig->group_exit_task = NULL; |
977 | sig->notify_count = 0; |
978 | |
979 | no_thread_group: |
980 | /* we have changed execution domain */ |
981 | tsk->exit_signal = SIGCHLD; |
982 | |
983 | exit_itimers(sig); |
984 | flush_itimer_signals(); |
985 | |
986 | if (atomic_read(&oldsighand->count) != 1) { |
987 | struct sighand_struct *newsighand; |
988 | /* |
989 | * This ->sighand is shared with the CLONE_SIGHAND |
990 | * but not CLONE_THREAD task, switch to the new one. |
991 | */ |
992 | newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); |
993 | if (!newsighand) |
994 | return -ENOMEM; |
995 | |
996 | atomic_set(&newsighand->count, 1); |
997 | memcpy(newsighand->action, oldsighand->action, |
998 | sizeof(newsighand->action)); |
999 | |
1000 | write_lock_irq(&tasklist_lock); |
1001 | spin_lock(&oldsighand->siglock); |
1002 | rcu_assign_pointer(tsk->sighand, newsighand); |
1003 | spin_unlock(&oldsighand->siglock); |
1004 | write_unlock_irq(&tasklist_lock); |
1005 | |
1006 | __cleanup_sighand(oldsighand); |
1007 | } |
1008 | |
1009 | BUG_ON(!thread_group_leader(tsk)); |
1010 | return 0; |
1011 | } |
1012 | |
1013 | /* |
1014 | * These functions flushes out all traces of the currently running executable |
1015 | * so that a new one can be started |
1016 | */ |
1017 | static void flush_old_files(struct files_struct * files) |
1018 | { |
1019 | long j = -1; |
1020 | struct fdtable *fdt; |
1021 | |
1022 | spin_lock(&files->file_lock); |
1023 | for (;;) { |
1024 | unsigned long set, i; |
1025 | |
1026 | j++; |
1027 | i = j * __NFDBITS; |
1028 | fdt = files_fdtable(files); |
1029 | if (i >= fdt->max_fds) |
1030 | break; |
1031 | set = fdt->close_on_exec[j]; |
1032 | if (!set) |
1033 | continue; |
1034 | fdt->close_on_exec[j] = 0; |
1035 | spin_unlock(&files->file_lock); |
1036 | for ( ; set ; i++,set >>= 1) { |
1037 | if (set & 1) { |
1038 | sys_close(i); |
1039 | } |
1040 | } |
1041 | spin_lock(&files->file_lock); |
1042 | |
1043 | } |
1044 | spin_unlock(&files->file_lock); |
1045 | } |
1046 | |
1047 | char *get_task_comm(char *buf, struct task_struct *tsk) |
1048 | { |
1049 | /* buf must be at least sizeof(tsk->comm) in size */ |
1050 | task_lock(tsk); |
1051 | strncpy(buf, tsk->comm, sizeof(tsk->comm)); |
1052 | task_unlock(tsk); |
1053 | return buf; |
1054 | } |
1055 | EXPORT_SYMBOL_GPL(get_task_comm); |
1056 | |
1057 | void set_task_comm(struct task_struct *tsk, char *buf) |
1058 | { |
1059 | task_lock(tsk); |
1060 | |
1061 | trace_task_rename(tsk, buf); |
1062 | |
1063 | /* |
1064 | * Threads may access current->comm without holding |
1065 | * the task lock, so write the string carefully. |
1066 | * Readers without a lock may see incomplete new |
1067 | * names but are safe from non-terminating string reads. |
1068 | */ |
1069 | memset(tsk->comm, 0, TASK_COMM_LEN); |
1070 | wmb(); |
1071 | strlcpy(tsk->comm, buf, sizeof(tsk->comm)); |
1072 | task_unlock(tsk); |
1073 | perf_event_comm(tsk); |
1074 | } |
1075 | |
1076 | static void filename_to_taskname(char *tcomm, const char *fn, unsigned int len) |
1077 | { |
1078 | int i, ch; |
1079 | |
1080 | /* Copies the binary name from after last slash */ |
1081 | for (i = 0; (ch = *(fn++)) != '\0';) { |
1082 | if (ch == '/') |
1083 | i = 0; /* overwrite what we wrote */ |
1084 | else |
1085 | if (i < len - 1) |
1086 | tcomm[i++] = ch; |
1087 | } |
1088 | tcomm[i] = '\0'; |
1089 | } |
1090 | |
1091 | int flush_old_exec(struct linux_binprm * bprm) |
1092 | { |
1093 | int retval; |
1094 | |
1095 | /* |
1096 | * Make sure we have a private signal table and that |
1097 | * we are unassociated from the previous thread group. |
1098 | */ |
1099 | retval = de_thread(current); |
1100 | if (retval) |
1101 | goto out; |
1102 | |
1103 | set_mm_exe_file(bprm->mm, bprm->file); |
1104 | |
1105 | filename_to_taskname(bprm->tcomm, bprm->filename, sizeof(bprm->tcomm)); |
1106 | /* |
1107 | * Release all of the old mmap stuff |
1108 | */ |
1109 | acct_arg_size(bprm, 0); |
1110 | retval = exec_mmap(bprm->mm); |
1111 | if (retval) |
1112 | goto out; |
1113 | |
1114 | bprm->mm = NULL; /* We're using it now */ |
1115 | |
1116 | set_fs(USER_DS); |
1117 | current->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD); |
1118 | flush_thread(); |
1119 | current->personality &= ~bprm->per_clear; |
1120 | |
1121 | return 0; |
1122 | |
1123 | out: |
1124 | return retval; |
1125 | } |
1126 | EXPORT_SYMBOL(flush_old_exec); |
1127 | |
1128 | void would_dump(struct linux_binprm *bprm, struct file *file) |
1129 | { |
1130 | if (inode_permission(file->f_path.dentry->d_inode, MAY_READ) < 0) |
1131 | bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP; |
1132 | } |
1133 | EXPORT_SYMBOL(would_dump); |
1134 | |
1135 | void setup_new_exec(struct linux_binprm * bprm) |
1136 | { |
1137 | arch_pick_mmap_layout(current->mm); |
1138 | |
1139 | /* This is the point of no return */ |
1140 | current->sas_ss_sp = current->sas_ss_size = 0; |
1141 | |
1142 | if (current_euid() == current_uid() && current_egid() == current_gid()) |
1143 | set_dumpable(current->mm, 1); |
1144 | else |
1145 | set_dumpable(current->mm, suid_dumpable); |
1146 | |
1147 | set_task_comm(current, bprm->tcomm); |
1148 | |
1149 | /* Set the new mm task size. We have to do that late because it may |
1150 | * depend on TIF_32BIT which is only updated in flush_thread() on |
1151 | * some architectures like powerpc |
1152 | */ |
1153 | current->mm->task_size = TASK_SIZE; |
1154 | |
1155 | /* install the new credentials */ |
1156 | if (bprm->cred->uid != current_euid() || |
1157 | bprm->cred->gid != current_egid()) { |
1158 | current->pdeath_signal = 0; |
1159 | } else { |
1160 | would_dump(bprm, bprm->file); |
1161 | if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) |
1162 | set_dumpable(current->mm, suid_dumpable); |
1163 | } |
1164 | |
1165 | /* |
1166 | * Flush performance counters when crossing a |
1167 | * security domain: |
1168 | */ |
1169 | if (!get_dumpable(current->mm)) |
1170 | perf_event_exit_task(current); |
1171 | |
1172 | /* An exec changes our domain. We are no longer part of the thread |
1173 | group */ |
1174 | |
1175 | current->self_exec_id++; |
1176 | |
1177 | flush_signal_handlers(current, 0); |
1178 | flush_old_files(current->files); |
1179 | } |
1180 | EXPORT_SYMBOL(setup_new_exec); |
1181 | |
1182 | /* |
1183 | * Prepare credentials and lock ->cred_guard_mutex. |
1184 | * install_exec_creds() commits the new creds and drops the lock. |
1185 | * Or, if exec fails before, free_bprm() should release ->cred and |
1186 | * and unlock. |
1187 | */ |
1188 | int prepare_bprm_creds(struct linux_binprm *bprm) |
1189 | { |
1190 | if (mutex_lock_interruptible(¤t->signal->cred_guard_mutex)) |
1191 | return -ERESTARTNOINTR; |
1192 | |
1193 | bprm->cred = prepare_exec_creds(); |
1194 | if (likely(bprm->cred)) |
1195 | return 0; |
1196 | |
1197 | mutex_unlock(¤t->signal->cred_guard_mutex); |
1198 | return -ENOMEM; |
1199 | } |
1200 | |
1201 | void free_bprm(struct linux_binprm *bprm) |
1202 | { |
1203 | free_arg_pages(bprm); |
1204 | if (bprm->cred) { |
1205 | mutex_unlock(¤t->signal->cred_guard_mutex); |
1206 | abort_creds(bprm->cred); |
1207 | } |
1208 | kfree(bprm); |
1209 | } |
1210 | |
1211 | /* |
1212 | * install the new credentials for this executable |
1213 | */ |
1214 | void install_exec_creds(struct linux_binprm *bprm) |
1215 | { |
1216 | security_bprm_committing_creds(bprm); |
1217 | |
1218 | commit_creds(bprm->cred); |
1219 | bprm->cred = NULL; |
1220 | /* |
1221 | * cred_guard_mutex must be held at least to this point to prevent |
1222 | * ptrace_attach() from altering our determination of the task's |
1223 | * credentials; any time after this it may be unlocked. |
1224 | */ |
1225 | security_bprm_committed_creds(bprm); |
1226 | mutex_unlock(¤t->signal->cred_guard_mutex); |
1227 | } |
1228 | EXPORT_SYMBOL(install_exec_creds); |
1229 | |
1230 | /* |
1231 | * determine how safe it is to execute the proposed program |
1232 | * - the caller must hold ->cred_guard_mutex to protect against |
1233 | * PTRACE_ATTACH |
1234 | */ |
1235 | static int check_unsafe_exec(struct linux_binprm *bprm) |
1236 | { |
1237 | struct task_struct *p = current, *t; |
1238 | unsigned n_fs; |
1239 | int res = 0; |
1240 | |
1241 | if (p->ptrace) { |
1242 | if (p->ptrace & PT_PTRACE_CAP) |
1243 | bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP; |
1244 | else |
1245 | bprm->unsafe |= LSM_UNSAFE_PTRACE; |
1246 | } |
1247 | |
1248 | n_fs = 1; |
1249 | spin_lock(&p->fs->lock); |
1250 | rcu_read_lock(); |
1251 | for (t = next_thread(p); t != p; t = next_thread(t)) { |
1252 | if (t->fs == p->fs) |
1253 | n_fs++; |
1254 | } |
1255 | rcu_read_unlock(); |
1256 | |
1257 | if (p->fs->users > n_fs) { |
1258 | bprm->unsafe |= LSM_UNSAFE_SHARE; |
1259 | } else { |
1260 | res = -EAGAIN; |
1261 | if (!p->fs->in_exec) { |
1262 | p->fs->in_exec = 1; |
1263 | res = 1; |
1264 | } |
1265 | } |
1266 | spin_unlock(&p->fs->lock); |
1267 | |
1268 | return res; |
1269 | } |
1270 | |
1271 | /* |
1272 | * Fill the binprm structure from the inode. |
1273 | * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes |
1274 | * |
1275 | * This may be called multiple times for binary chains (scripts for example). |
1276 | */ |
1277 | int prepare_binprm(struct linux_binprm *bprm) |
1278 | { |
1279 | umode_t mode; |
1280 | struct inode * inode = bprm->file->f_path.dentry->d_inode; |
1281 | int retval; |
1282 | |
1283 | mode = inode->i_mode; |
1284 | if (bprm->file->f_op == NULL) |
1285 | return -EACCES; |
1286 | |
1287 | /* clear any previous set[ug]id data from a previous binary */ |
1288 | bprm->cred->euid = current_euid(); |
1289 | bprm->cred->egid = current_egid(); |
1290 | |
1291 | if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) { |
1292 | /* Set-uid? */ |
1293 | if (mode & S_ISUID) { |
1294 | bprm->per_clear |= PER_CLEAR_ON_SETID; |
1295 | bprm->cred->euid = inode->i_uid; |
1296 | } |
1297 | |
1298 | /* Set-gid? */ |
1299 | /* |
1300 | * If setgid is set but no group execute bit then this |
1301 | * is a candidate for mandatory locking, not a setgid |
1302 | * executable. |
1303 | */ |
1304 | if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { |
1305 | bprm->per_clear |= PER_CLEAR_ON_SETID; |
1306 | bprm->cred->egid = inode->i_gid; |
1307 | } |
1308 | } |
1309 | |
1310 | /* fill in binprm security blob */ |
1311 | retval = security_bprm_set_creds(bprm); |
1312 | if (retval) |
1313 | return retval; |
1314 | bprm->cred_prepared = 1; |
1315 | |
1316 | memset(bprm->buf, 0, BINPRM_BUF_SIZE); |
1317 | return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE); |
1318 | } |
1319 | |
1320 | EXPORT_SYMBOL(prepare_binprm); |
1321 | |
1322 | /* |
1323 | * Arguments are '\0' separated strings found at the location bprm->p |
1324 | * points to; chop off the first by relocating brpm->p to right after |
1325 | * the first '\0' encountered. |
1326 | */ |
1327 | int remove_arg_zero(struct linux_binprm *bprm) |
1328 | { |
1329 | int ret = 0; |
1330 | unsigned long offset; |
1331 | char *kaddr; |
1332 | struct page *page; |
1333 | |
1334 | if (!bprm->argc) |
1335 | return 0; |
1336 | |
1337 | do { |
1338 | offset = bprm->p & ~PAGE_MASK; |
1339 | page = get_arg_page(bprm, bprm->p, 0); |
1340 | if (!page) { |
1341 | ret = -EFAULT; |
1342 | goto out; |
1343 | } |
1344 | kaddr = kmap_atomic(page); |
1345 | |
1346 | for (; offset < PAGE_SIZE && kaddr[offset]; |
1347 | offset++, bprm->p++) |
1348 | ; |
1349 | |
1350 | kunmap_atomic(kaddr); |
1351 | put_arg_page(page); |
1352 | |
1353 | if (offset == PAGE_SIZE) |
1354 | free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1); |
1355 | } while (offset == PAGE_SIZE); |
1356 | |
1357 | bprm->p++; |
1358 | bprm->argc--; |
1359 | ret = 0; |
1360 | |
1361 | out: |
1362 | return ret; |
1363 | } |
1364 | EXPORT_SYMBOL(remove_arg_zero); |
1365 | |
1366 | /* |
1367 | * cycle the list of binary formats handler, until one recognizes the image |
1368 | */ |
1369 | int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs) |
1370 | { |
1371 | unsigned int depth = bprm->recursion_depth; |
1372 | int try,retval; |
1373 | struct linux_binfmt *fmt; |
1374 | pid_t old_pid, old_vpid; |
1375 | |
1376 | retval = security_bprm_check(bprm); |
1377 | if (retval) |
1378 | return retval; |
1379 | |
1380 | retval = audit_bprm(bprm); |
1381 | if (retval) |
1382 | return retval; |
1383 | |
1384 | /* Need to fetch pid before load_binary changes it */ |
1385 | old_pid = current->pid; |
1386 | rcu_read_lock(); |
1387 | old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent)); |
1388 | rcu_read_unlock(); |
1389 | |
1390 | retval = -ENOENT; |
1391 | for (try=0; try<2; try++) { |
1392 | read_lock(&binfmt_lock); |
1393 | list_for_each_entry(fmt, &formats, lh) { |
1394 | int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary; |
1395 | if (!fn) |
1396 | continue; |
1397 | if (!try_module_get(fmt->module)) |
1398 | continue; |
1399 | read_unlock(&binfmt_lock); |
1400 | retval = fn(bprm, regs); |
1401 | /* |
1402 | * Restore the depth counter to its starting value |
1403 | * in this call, so we don't have to rely on every |
1404 | * load_binary function to restore it on return. |
1405 | */ |
1406 | bprm->recursion_depth = depth; |
1407 | if (retval >= 0) { |
1408 | if (depth == 0) { |
1409 | trace_sched_process_exec(current, old_pid, bprm); |
1410 | ptrace_event(PTRACE_EVENT_EXEC, old_vpid); |
1411 | } |
1412 | put_binfmt(fmt); |
1413 | allow_write_access(bprm->file); |
1414 | if (bprm->file) |
1415 | fput(bprm->file); |
1416 | bprm->file = NULL; |
1417 | current->did_exec = 1; |
1418 | proc_exec_connector(current); |
1419 | return retval; |
1420 | } |
1421 | read_lock(&binfmt_lock); |
1422 | put_binfmt(fmt); |
1423 | if (retval != -ENOEXEC || bprm->mm == NULL) |
1424 | break; |
1425 | if (!bprm->file) { |
1426 | read_unlock(&binfmt_lock); |
1427 | return retval; |
1428 | } |
1429 | } |
1430 | read_unlock(&binfmt_lock); |
1431 | #ifdef CONFIG_MODULES |
1432 | if (retval != -ENOEXEC || bprm->mm == NULL) { |
1433 | break; |
1434 | } else { |
1435 | #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e)) |
1436 | if (printable(bprm->buf[0]) && |
1437 | printable(bprm->buf[1]) && |
1438 | printable(bprm->buf[2]) && |
1439 | printable(bprm->buf[3])) |
1440 | break; /* -ENOEXEC */ |
1441 | if (try) |
1442 | break; /* -ENOEXEC */ |
1443 | request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2])); |
1444 | } |
1445 | #else |
1446 | break; |
1447 | #endif |
1448 | } |
1449 | return retval; |
1450 | } |
1451 | |
1452 | EXPORT_SYMBOL(search_binary_handler); |
1453 | |
1454 | /* |
1455 | * sys_execve() executes a new program. |
1456 | */ |
1457 | static int do_execve_common(const char *filename, |
1458 | struct user_arg_ptr argv, |
1459 | struct user_arg_ptr envp, |
1460 | struct pt_regs *regs) |
1461 | { |
1462 | struct linux_binprm *bprm; |
1463 | struct file *file; |
1464 | struct files_struct *displaced; |
1465 | bool clear_in_exec; |
1466 | int retval; |
1467 | const struct cred *cred = current_cred(); |
1468 | |
1469 | /* |
1470 | * We move the actual failure in case of RLIMIT_NPROC excess from |
1471 | * set*uid() to execve() because too many poorly written programs |
1472 | * don't check setuid() return code. Here we additionally recheck |
1473 | * whether NPROC limit is still exceeded. |
1474 | */ |
1475 | if ((current->flags & PF_NPROC_EXCEEDED) && |
1476 | atomic_read(&cred->user->processes) > rlimit(RLIMIT_NPROC)) { |
1477 | retval = -EAGAIN; |
1478 | goto out_ret; |
1479 | } |
1480 | |
1481 | /* We're below the limit (still or again), so we don't want to make |
1482 | * further execve() calls fail. */ |
1483 | current->flags &= ~PF_NPROC_EXCEEDED; |
1484 | |
1485 | retval = unshare_files(&displaced); |
1486 | if (retval) |
1487 | goto out_ret; |
1488 | |
1489 | retval = -ENOMEM; |
1490 | bprm = kzalloc(sizeof(*bprm), GFP_KERNEL); |
1491 | if (!bprm) |
1492 | goto out_files; |
1493 | |
1494 | retval = prepare_bprm_creds(bprm); |
1495 | if (retval) |
1496 | goto out_free; |
1497 | |
1498 | retval = check_unsafe_exec(bprm); |
1499 | if (retval < 0) |
1500 | goto out_free; |
1501 | clear_in_exec = retval; |
1502 | current->in_execve = 1; |
1503 | |
1504 | file = open_exec(filename); |
1505 | retval = PTR_ERR(file); |
1506 | if (IS_ERR(file)) |
1507 | goto out_unmark; |
1508 | |
1509 | sched_exec(); |
1510 | |
1511 | bprm->file = file; |
1512 | bprm->filename = filename; |
1513 | bprm->interp = filename; |
1514 | |
1515 | retval = bprm_mm_init(bprm); |
1516 | if (retval) |
1517 | goto out_file; |
1518 | |
1519 | bprm->argc = count(argv, MAX_ARG_STRINGS); |
1520 | if ((retval = bprm->argc) < 0) |
1521 | goto out; |
1522 | |
1523 | bprm->envc = count(envp, MAX_ARG_STRINGS); |
1524 | if ((retval = bprm->envc) < 0) |
1525 | goto out; |
1526 | |
1527 | retval = prepare_binprm(bprm); |
1528 | if (retval < 0) |
1529 | goto out; |
1530 | |
1531 | retval = copy_strings_kernel(1, &bprm->filename, bprm); |
1532 | if (retval < 0) |
1533 | goto out; |
1534 | |
1535 | bprm->exec = bprm->p; |
1536 | retval = copy_strings(bprm->envc, envp, bprm); |
1537 | if (retval < 0) |
1538 | goto out; |
1539 | |
1540 | retval = copy_strings(bprm->argc, argv, bprm); |
1541 | if (retval < 0) |
1542 | goto out; |
1543 | |
1544 | retval = search_binary_handler(bprm,regs); |
1545 | if (retval < 0) |
1546 | goto out; |
1547 | |
1548 | /* execve succeeded */ |
1549 | current->fs->in_exec = 0; |
1550 | current->in_execve = 0; |
1551 | acct_update_integrals(current); |
1552 | free_bprm(bprm); |
1553 | if (displaced) |
1554 | put_files_struct(displaced); |
1555 | return retval; |
1556 | |
1557 | out: |
1558 | if (bprm->mm) { |
1559 | acct_arg_size(bprm, 0); |
1560 | mmput(bprm->mm); |
1561 | } |
1562 | |
1563 | out_file: |
1564 | if (bprm->file) { |
1565 | allow_write_access(bprm->file); |
1566 | fput(bprm->file); |
1567 | } |
1568 | |
1569 | out_unmark: |
1570 | if (clear_in_exec) |
1571 | current->fs->in_exec = 0; |
1572 | current->in_execve = 0; |
1573 | |
1574 | out_free: |
1575 | free_bprm(bprm); |
1576 | |
1577 | out_files: |
1578 | if (displaced) |
1579 | reset_files_struct(displaced); |
1580 | out_ret: |
1581 | return retval; |
1582 | } |
1583 | |
1584 | int do_execve(const char *filename, |
1585 | const char __user *const __user *__argv, |
1586 | const char __user *const __user *__envp, |
1587 | struct pt_regs *regs) |
1588 | { |
1589 | struct user_arg_ptr argv = { .ptr.native = __argv }; |
1590 | struct user_arg_ptr envp = { .ptr.native = __envp }; |
1591 | return do_execve_common(filename, argv, envp, regs); |
1592 | } |
1593 | |
1594 | #ifdef CONFIG_COMPAT |
1595 | int compat_do_execve(char *filename, |
1596 | compat_uptr_t __user *__argv, |
1597 | compat_uptr_t __user *__envp, |
1598 | struct pt_regs *regs) |
1599 | { |
1600 | struct user_arg_ptr argv = { |
1601 | .is_compat = true, |
1602 | .ptr.compat = __argv, |
1603 | }; |
1604 | struct user_arg_ptr envp = { |
1605 | .is_compat = true, |
1606 | .ptr.compat = __envp, |
1607 | }; |
1608 | return do_execve_common(filename, argv, envp, regs); |
1609 | } |
1610 | #endif |
1611 | |
1612 | void set_binfmt(struct linux_binfmt *new) |
1613 | { |
1614 | struct mm_struct *mm = current->mm; |
1615 | |
1616 | if (mm->binfmt) |
1617 | module_put(mm->binfmt->module); |
1618 | |
1619 | mm->binfmt = new; |
1620 | if (new) |
1621 | __module_get(new->module); |
1622 | } |
1623 | |
1624 | EXPORT_SYMBOL(set_binfmt); |
1625 | |
1626 | static int expand_corename(struct core_name *cn) |
1627 | { |
1628 | char *old_corename = cn->corename; |
1629 | |
1630 | cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count); |
1631 | cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL); |
1632 | |
1633 | if (!cn->corename) { |
1634 | kfree(old_corename); |
1635 | return -ENOMEM; |
1636 | } |
1637 | |
1638 | return 0; |
1639 | } |
1640 | |
1641 | static int cn_printf(struct core_name *cn, const char *fmt, ...) |
1642 | { |
1643 | char *cur; |
1644 | int need; |
1645 | int ret; |
1646 | va_list arg; |
1647 | |
1648 | va_start(arg, fmt); |
1649 | need = vsnprintf(NULL, 0, fmt, arg); |
1650 | va_end(arg); |
1651 | |
1652 | if (likely(need < cn->size - cn->used - 1)) |
1653 | goto out_printf; |
1654 | |
1655 | ret = expand_corename(cn); |
1656 | if (ret) |
1657 | goto expand_fail; |
1658 | |
1659 | out_printf: |
1660 | cur = cn->corename + cn->used; |
1661 | va_start(arg, fmt); |
1662 | vsnprintf(cur, need + 1, fmt, arg); |
1663 | va_end(arg); |
1664 | cn->used += need; |
1665 | return 0; |
1666 | |
1667 | expand_fail: |
1668 | return ret; |
1669 | } |
1670 | |
1671 | static void cn_escape(char *str) |
1672 | { |
1673 | for (; *str; str++) |
1674 | if (*str == '/') |
1675 | *str = '!'; |
1676 | } |
1677 | |
1678 | static int cn_print_exe_file(struct core_name *cn) |
1679 | { |
1680 | struct file *exe_file; |
1681 | char *pathbuf, *path; |
1682 | int ret; |
1683 | |
1684 | exe_file = get_mm_exe_file(current->mm); |
1685 | if (!exe_file) { |
1686 | char *commstart = cn->corename + cn->used; |
1687 | ret = cn_printf(cn, "%s (path unknown)", current->comm); |
1688 | cn_escape(commstart); |
1689 | return ret; |
1690 | } |
1691 | |
1692 | pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY); |
1693 | if (!pathbuf) { |
1694 | ret = -ENOMEM; |
1695 | goto put_exe_file; |
1696 | } |
1697 | |
1698 | path = d_path(&exe_file->f_path, pathbuf, PATH_MAX); |
1699 | if (IS_ERR(path)) { |
1700 | ret = PTR_ERR(path); |
1701 | goto free_buf; |
1702 | } |
1703 | |
1704 | cn_escape(path); |
1705 | |
1706 | ret = cn_printf(cn, "%s", path); |
1707 | |
1708 | free_buf: |
1709 | kfree(pathbuf); |
1710 | put_exe_file: |
1711 | fput(exe_file); |
1712 | return ret; |
1713 | } |
1714 | |
1715 | /* format_corename will inspect the pattern parameter, and output a |
1716 | * name into corename, which must have space for at least |
1717 | * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator. |
1718 | */ |
1719 | static int format_corename(struct core_name *cn, long signr) |
1720 | { |
1721 | const struct cred *cred = current_cred(); |
1722 | const char *pat_ptr = core_pattern; |
1723 | int ispipe = (*pat_ptr == '|'); |
1724 | int pid_in_pattern = 0; |
1725 | int err = 0; |
1726 | |
1727 | cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count); |
1728 | cn->corename = kmalloc(cn->size, GFP_KERNEL); |
1729 | cn->used = 0; |
1730 | |
1731 | if (!cn->corename) |
1732 | return -ENOMEM; |
1733 | |
1734 | /* Repeat as long as we have more pattern to process and more output |
1735 | space */ |
1736 | while (*pat_ptr) { |
1737 | if (*pat_ptr != '%') { |
1738 | if (*pat_ptr == 0) |
1739 | goto out; |
1740 | err = cn_printf(cn, "%c", *pat_ptr++); |
1741 | } else { |
1742 | switch (*++pat_ptr) { |
1743 | /* single % at the end, drop that */ |
1744 | case 0: |
1745 | goto out; |
1746 | /* Double percent, output one percent */ |
1747 | case '%': |
1748 | err = cn_printf(cn, "%c", '%'); |
1749 | break; |
1750 | /* pid */ |
1751 | case 'p': |
1752 | pid_in_pattern = 1; |
1753 | err = cn_printf(cn, "%d", |
1754 | task_tgid_vnr(current)); |
1755 | break; |
1756 | /* uid */ |
1757 | case 'u': |
1758 | err = cn_printf(cn, "%d", cred->uid); |
1759 | break; |
1760 | /* gid */ |
1761 | case 'g': |
1762 | err = cn_printf(cn, "%d", cred->gid); |
1763 | break; |
1764 | /* signal that caused the coredump */ |
1765 | case 's': |
1766 | err = cn_printf(cn, "%ld", signr); |
1767 | break; |
1768 | /* UNIX time of coredump */ |
1769 | case 't': { |
1770 | struct timeval tv; |
1771 | do_gettimeofday(&tv); |
1772 | err = cn_printf(cn, "%lu", tv.tv_sec); |
1773 | break; |
1774 | } |
1775 | /* hostname */ |
1776 | case 'h': { |
1777 | char *namestart = cn->corename + cn->used; |
1778 | down_read(&uts_sem); |
1779 | err = cn_printf(cn, "%s", |
1780 | utsname()->nodename); |
1781 | up_read(&uts_sem); |
1782 | cn_escape(namestart); |
1783 | break; |
1784 | } |
1785 | /* executable */ |
1786 | case 'e': { |
1787 | char *commstart = cn->corename + cn->used; |
1788 | err = cn_printf(cn, "%s", current->comm); |
1789 | cn_escape(commstart); |
1790 | break; |
1791 | } |
1792 | case 'E': |
1793 | err = cn_print_exe_file(cn); |
1794 | break; |
1795 | /* core limit size */ |
1796 | case 'c': |
1797 | err = cn_printf(cn, "%lu", |
1798 | rlimit(RLIMIT_CORE)); |
1799 | break; |
1800 | default: |
1801 | break; |
1802 | } |
1803 | ++pat_ptr; |
1804 | } |
1805 | |
1806 | if (err) |
1807 | return err; |
1808 | } |
1809 | |
1810 | /* Backward compatibility with core_uses_pid: |
1811 | * |
1812 | * If core_pattern does not include a %p (as is the default) |
1813 | * and core_uses_pid is set, then .%pid will be appended to |
1814 | * the filename. Do not do this for piped commands. */ |
1815 | if (!ispipe && !pid_in_pattern && core_uses_pid) { |
1816 | err = cn_printf(cn, ".%d", task_tgid_vnr(current)); |
1817 | if (err) |
1818 | return err; |
1819 | } |
1820 | out: |
1821 | return ispipe; |
1822 | } |
1823 | |
1824 | static int zap_process(struct task_struct *start, int exit_code) |
1825 | { |
1826 | struct task_struct *t; |
1827 | int nr = 0; |
1828 | |
1829 | start->signal->flags = SIGNAL_GROUP_EXIT; |
1830 | start->signal->group_exit_code = exit_code; |
1831 | start->signal->group_stop_count = 0; |
1832 | |
1833 | t = start; |
1834 | do { |
1835 | task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); |
1836 | if (t != current && t->mm) { |
1837 | sigaddset(&t->pending.signal, SIGKILL); |
1838 | signal_wake_up(t, 1); |
1839 | nr++; |
1840 | } |
1841 | } while_each_thread(start, t); |
1842 | |
1843 | return nr; |
1844 | } |
1845 | |
1846 | static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm, |
1847 | struct core_state *core_state, int exit_code) |
1848 | { |
1849 | struct task_struct *g, *p; |
1850 | unsigned long flags; |
1851 | int nr = -EAGAIN; |
1852 | |
1853 | spin_lock_irq(&tsk->sighand->siglock); |
1854 | if (!signal_group_exit(tsk->signal)) { |
1855 | mm->core_state = core_state; |
1856 | nr = zap_process(tsk, exit_code); |
1857 | } |
1858 | spin_unlock_irq(&tsk->sighand->siglock); |
1859 | if (unlikely(nr < 0)) |
1860 | return nr; |
1861 | |
1862 | if (atomic_read(&mm->mm_users) == nr + 1) |
1863 | goto done; |
1864 | /* |
1865 | * We should find and kill all tasks which use this mm, and we should |
1866 | * count them correctly into ->nr_threads. We don't take tasklist |
1867 | * lock, but this is safe wrt: |
1868 | * |
1869 | * fork: |
1870 | * None of sub-threads can fork after zap_process(leader). All |
1871 | * processes which were created before this point should be |
1872 | * visible to zap_threads() because copy_process() adds the new |
1873 | * process to the tail of init_task.tasks list, and lock/unlock |
1874 | * of ->siglock provides a memory barrier. |
1875 | * |
1876 | * do_exit: |
1877 | * The caller holds mm->mmap_sem. This means that the task which |
1878 | * uses this mm can't pass exit_mm(), so it can't exit or clear |
1879 | * its ->mm. |
1880 | * |
1881 | * de_thread: |
1882 | * It does list_replace_rcu(&leader->tasks, ¤t->tasks), |
1883 | * we must see either old or new leader, this does not matter. |
1884 | * However, it can change p->sighand, so lock_task_sighand(p) |
1885 | * must be used. Since p->mm != NULL and we hold ->mmap_sem |
1886 | * it can't fail. |
1887 | * |
1888 | * Note also that "g" can be the old leader with ->mm == NULL |
1889 | * and already unhashed and thus removed from ->thread_group. |
1890 | * This is OK, __unhash_process()->list_del_rcu() does not |
1891 | * clear the ->next pointer, we will find the new leader via |
1892 | * next_thread(). |
1893 | */ |
1894 | rcu_read_lock(); |
1895 | for_each_process(g) { |
1896 | if (g == tsk->group_leader) |
1897 | continue; |
1898 | if (g->flags & PF_KTHREAD) |
1899 | continue; |
1900 | p = g; |
1901 | do { |
1902 | if (p->mm) { |
1903 | if (unlikely(p->mm == mm)) { |
1904 | lock_task_sighand(p, &flags); |
1905 | nr += zap_process(p, exit_code); |
1906 | unlock_task_sighand(p, &flags); |
1907 | } |
1908 | break; |
1909 | } |
1910 | } while_each_thread(g, p); |
1911 | } |
1912 | rcu_read_unlock(); |
1913 | done: |
1914 | atomic_set(&core_state->nr_threads, nr); |
1915 | return nr; |
1916 | } |
1917 | |
1918 | static int coredump_wait(int exit_code, struct core_state *core_state) |
1919 | { |
1920 | struct task_struct *tsk = current; |
1921 | struct mm_struct *mm = tsk->mm; |
1922 | int core_waiters = -EBUSY; |
1923 | |
1924 | init_completion(&core_state->startup); |
1925 | core_state->dumper.task = tsk; |
1926 | core_state->dumper.next = NULL; |
1927 | |
1928 | down_write(&mm->mmap_sem); |
1929 | if (!mm->core_state) |
1930 | core_waiters = zap_threads(tsk, mm, core_state, exit_code); |
1931 | up_write(&mm->mmap_sem); |
1932 | |
1933 | if (core_waiters > 0) |
1934 | wait_for_completion(&core_state->startup); |
1935 | |
1936 | return core_waiters; |
1937 | } |
1938 | |
1939 | static void coredump_finish(struct mm_struct *mm) |
1940 | { |
1941 | struct core_thread *curr, *next; |
1942 | struct task_struct *task; |
1943 | |
1944 | next = mm->core_state->dumper.next; |
1945 | while ((curr = next) != NULL) { |
1946 | next = curr->next; |
1947 | task = curr->task; |
1948 | /* |
1949 | * see exit_mm(), curr->task must not see |
1950 | * ->task == NULL before we read ->next. |
1951 | */ |
1952 | smp_mb(); |
1953 | curr->task = NULL; |
1954 | wake_up_process(task); |
1955 | } |
1956 | |
1957 | mm->core_state = NULL; |
1958 | } |
1959 | |
1960 | /* |
1961 | * set_dumpable converts traditional three-value dumpable to two flags and |
1962 | * stores them into mm->flags. It modifies lower two bits of mm->flags, but |
1963 | * these bits are not changed atomically. So get_dumpable can observe the |
1964 | * intermediate state. To avoid doing unexpected behavior, get get_dumpable |
1965 | * return either old dumpable or new one by paying attention to the order of |
1966 | * modifying the bits. |
1967 | * |
1968 | * dumpable | mm->flags (binary) |
1969 | * old new | initial interim final |
1970 | * ---------+----------------------- |
1971 | * 0 1 | 00 01 01 |
1972 | * 0 2 | 00 10(*) 11 |
1973 | * 1 0 | 01 00 00 |
1974 | * 1 2 | 01 11 11 |
1975 | * 2 0 | 11 10(*) 00 |
1976 | * 2 1 | 11 11 01 |
1977 | * |
1978 | * (*) get_dumpable regards interim value of 10 as 11. |
1979 | */ |
1980 | void set_dumpable(struct mm_struct *mm, int value) |
1981 | { |
1982 | switch (value) { |
1983 | case 0: |
1984 | clear_bit(MMF_DUMPABLE, &mm->flags); |
1985 | smp_wmb(); |
1986 | clear_bit(MMF_DUMP_SECURELY, &mm->flags); |
1987 | break; |
1988 | case 1: |
1989 | set_bit(MMF_DUMPABLE, &mm->flags); |
1990 | smp_wmb(); |
1991 | clear_bit(MMF_DUMP_SECURELY, &mm->flags); |
1992 | break; |
1993 | case 2: |
1994 | set_bit(MMF_DUMP_SECURELY, &mm->flags); |
1995 | smp_wmb(); |
1996 | set_bit(MMF_DUMPABLE, &mm->flags); |
1997 | break; |
1998 | } |
1999 | } |
2000 | |
2001 | static int __get_dumpable(unsigned long mm_flags) |
2002 | { |
2003 | int ret; |
2004 | |
2005 | ret = mm_flags & MMF_DUMPABLE_MASK; |
2006 | return (ret >= 2) ? 2 : ret; |
2007 | } |
2008 | |
2009 | int get_dumpable(struct mm_struct *mm) |
2010 | { |
2011 | return __get_dumpable(mm->flags); |
2012 | } |
2013 | |
2014 | static void wait_for_dump_helpers(struct file *file) |
2015 | { |
2016 | struct pipe_inode_info *pipe; |
2017 | |
2018 | pipe = file->f_path.dentry->d_inode->i_pipe; |
2019 | |
2020 | pipe_lock(pipe); |
2021 | pipe->readers++; |
2022 | pipe->writers--; |
2023 | |
2024 | while ((pipe->readers > 1) && (!signal_pending(current))) { |
2025 | wake_up_interruptible_sync(&pipe->wait); |
2026 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
2027 | pipe_wait(pipe); |
2028 | } |
2029 | |
2030 | pipe->readers--; |
2031 | pipe->writers++; |
2032 | pipe_unlock(pipe); |
2033 | |
2034 | } |
2035 | |
2036 | |
2037 | /* |
2038 | * umh_pipe_setup |
2039 | * helper function to customize the process used |
2040 | * to collect the core in userspace. Specifically |
2041 | * it sets up a pipe and installs it as fd 0 (stdin) |
2042 | * for the process. Returns 0 on success, or |
2043 | * PTR_ERR on failure. |
2044 | * Note that it also sets the core limit to 1. This |
2045 | * is a special value that we use to trap recursive |
2046 | * core dumps |
2047 | */ |
2048 | static int umh_pipe_setup(struct subprocess_info *info, struct cred *new) |
2049 | { |
2050 | struct file *rp, *wp; |
2051 | struct fdtable *fdt; |
2052 | struct coredump_params *cp = (struct coredump_params *)info->data; |
2053 | struct files_struct *cf = current->files; |
2054 | |
2055 | wp = create_write_pipe(0); |
2056 | if (IS_ERR(wp)) |
2057 | return PTR_ERR(wp); |
2058 | |
2059 | rp = create_read_pipe(wp, 0); |
2060 | if (IS_ERR(rp)) { |
2061 | free_write_pipe(wp); |
2062 | return PTR_ERR(rp); |
2063 | } |
2064 | |
2065 | cp->file = wp; |
2066 | |
2067 | sys_close(0); |
2068 | fd_install(0, rp); |
2069 | spin_lock(&cf->file_lock); |
2070 | fdt = files_fdtable(cf); |
2071 | __set_open_fd(0, fdt); |
2072 | __clear_close_on_exec(0, fdt); |
2073 | spin_unlock(&cf->file_lock); |
2074 | |
2075 | /* and disallow core files too */ |
2076 | current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1}; |
2077 | |
2078 | return 0; |
2079 | } |
2080 | |
2081 | void do_coredump(long signr, int exit_code, struct pt_regs *regs) |
2082 | { |
2083 | struct core_state core_state; |
2084 | struct core_name cn; |
2085 | struct mm_struct *mm = current->mm; |
2086 | struct linux_binfmt * binfmt; |
2087 | const struct cred *old_cred; |
2088 | struct cred *cred; |
2089 | int retval = 0; |
2090 | int flag = 0; |
2091 | int ispipe; |
2092 | static atomic_t core_dump_count = ATOMIC_INIT(0); |
2093 | struct coredump_params cprm = { |
2094 | .signr = signr, |
2095 | .regs = regs, |
2096 | .limit = rlimit(RLIMIT_CORE), |
2097 | /* |
2098 | * We must use the same mm->flags while dumping core to avoid |
2099 | * inconsistency of bit flags, since this flag is not protected |
2100 | * by any locks. |
2101 | */ |
2102 | .mm_flags = mm->flags, |
2103 | }; |
2104 | |
2105 | audit_core_dumps(signr); |
2106 | |
2107 | binfmt = mm->binfmt; |
2108 | if (!binfmt || !binfmt->core_dump) |
2109 | goto fail; |
2110 | if (!__get_dumpable(cprm.mm_flags)) |
2111 | goto fail; |
2112 | |
2113 | cred = prepare_creds(); |
2114 | if (!cred) |
2115 | goto fail; |
2116 | /* |
2117 | * We cannot trust fsuid as being the "true" uid of the |
2118 | * process nor do we know its entire history. We only know it |
2119 | * was tainted so we dump it as root in mode 2. |
2120 | */ |
2121 | if (__get_dumpable(cprm.mm_flags) == 2) { |
2122 | /* Setuid core dump mode */ |
2123 | flag = O_EXCL; /* Stop rewrite attacks */ |
2124 | cred->fsuid = 0; /* Dump root private */ |
2125 | } |
2126 | |
2127 | retval = coredump_wait(exit_code, &core_state); |
2128 | if (retval < 0) |
2129 | goto fail_creds; |
2130 | |
2131 | old_cred = override_creds(cred); |
2132 | |
2133 | /* |
2134 | * Clear any false indication of pending signals that might |
2135 | * be seen by the filesystem code called to write the core file. |
2136 | */ |
2137 | clear_thread_flag(TIF_SIGPENDING); |
2138 | |
2139 | ispipe = format_corename(&cn, signr); |
2140 | |
2141 | if (ispipe) { |
2142 | int dump_count; |
2143 | char **helper_argv; |
2144 | |
2145 | if (ispipe < 0) { |
2146 | printk(KERN_WARNING "format_corename failed\n"); |
2147 | printk(KERN_WARNING "Aborting core\n"); |
2148 | goto fail_corename; |
2149 | } |
2150 | |
2151 | if (cprm.limit == 1) { |
2152 | /* |
2153 | * Normally core limits are irrelevant to pipes, since |
2154 | * we're not writing to the file system, but we use |
2155 | * cprm.limit of 1 here as a speacial value. Any |
2156 | * non-1 limit gets set to RLIM_INFINITY below, but |
2157 | * a limit of 0 skips the dump. This is a consistent |
2158 | * way to catch recursive crashes. We can still crash |
2159 | * if the core_pattern binary sets RLIM_CORE = !1 |
2160 | * but it runs as root, and can do lots of stupid things |
2161 | * Note that we use task_tgid_vnr here to grab the pid |
2162 | * of the process group leader. That way we get the |
2163 | * right pid if a thread in a multi-threaded |
2164 | * core_pattern process dies. |
2165 | */ |
2166 | printk(KERN_WARNING |
2167 | "Process %d(%s) has RLIMIT_CORE set to 1\n", |
2168 | task_tgid_vnr(current), current->comm); |
2169 | printk(KERN_WARNING "Aborting core\n"); |
2170 | goto fail_unlock; |
2171 | } |
2172 | cprm.limit = RLIM_INFINITY; |
2173 | |
2174 | dump_count = atomic_inc_return(&core_dump_count); |
2175 | if (core_pipe_limit && (core_pipe_limit < dump_count)) { |
2176 | printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n", |
2177 | task_tgid_vnr(current), current->comm); |
2178 | printk(KERN_WARNING "Skipping core dump\n"); |
2179 | goto fail_dropcount; |
2180 | } |
2181 | |
2182 | helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL); |
2183 | if (!helper_argv) { |
2184 | printk(KERN_WARNING "%s failed to allocate memory\n", |
2185 | __func__); |
2186 | goto fail_dropcount; |
2187 | } |
2188 | |
2189 | retval = call_usermodehelper_fns(helper_argv[0], helper_argv, |
2190 | NULL, UMH_WAIT_EXEC, umh_pipe_setup, |
2191 | NULL, &cprm); |
2192 | argv_free(helper_argv); |
2193 | if (retval) { |
2194 | printk(KERN_INFO "Core dump to %s pipe failed\n", |
2195 | cn.corename); |
2196 | goto close_fail; |
2197 | } |
2198 | } else { |
2199 | struct inode *inode; |
2200 | |
2201 | if (cprm.limit < binfmt->min_coredump) |
2202 | goto fail_unlock; |
2203 | |
2204 | cprm.file = filp_open(cn.corename, |
2205 | O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, |
2206 | 0600); |
2207 | if (IS_ERR(cprm.file)) |
2208 | goto fail_unlock; |
2209 | |
2210 | inode = cprm.file->f_path.dentry->d_inode; |
2211 | if (inode->i_nlink > 1) |
2212 | goto close_fail; |
2213 | if (d_unhashed(cprm.file->f_path.dentry)) |
2214 | goto close_fail; |
2215 | /* |
2216 | * AK: actually i see no reason to not allow this for named |
2217 | * pipes etc, but keep the previous behaviour for now. |
2218 | */ |
2219 | if (!S_ISREG(inode->i_mode)) |
2220 | goto close_fail; |
2221 | /* |
2222 | * Dont allow local users get cute and trick others to coredump |
2223 | * into their pre-created files. |
2224 | */ |
2225 | if (inode->i_uid != current_fsuid()) |
2226 | goto close_fail; |
2227 | if (!cprm.file->f_op || !cprm.file->f_op->write) |
2228 | goto close_fail; |
2229 | if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file)) |
2230 | goto close_fail; |
2231 | } |
2232 | |
2233 | retval = binfmt->core_dump(&cprm); |
2234 | if (retval) |
2235 | current->signal->group_exit_code |= 0x80; |
2236 | |
2237 | if (ispipe && core_pipe_limit) |
2238 | wait_for_dump_helpers(cprm.file); |
2239 | close_fail: |
2240 | if (cprm.file) |
2241 | filp_close(cprm.file, NULL); |
2242 | fail_dropcount: |
2243 | if (ispipe) |
2244 | atomic_dec(&core_dump_count); |
2245 | fail_unlock: |
2246 | kfree(cn.corename); |
2247 | fail_corename: |
2248 | coredump_finish(mm); |
2249 | revert_creds(old_cred); |
2250 | fail_creds: |
2251 | put_cred(cred); |
2252 | fail: |
2253 | return; |
2254 | } |
2255 | |
2256 | /* |
2257 | * Core dumping helper functions. These are the only things you should |
2258 | * do on a core-file: use only these functions to write out all the |
2259 | * necessary info. |
2260 | */ |
2261 | int dump_write(struct file *file, const void *addr, int nr) |
2262 | { |
2263 | return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr; |
2264 | } |
2265 | EXPORT_SYMBOL(dump_write); |
2266 | |
2267 | int dump_seek(struct file *file, loff_t off) |
2268 | { |
2269 | int ret = 1; |
2270 | |
2271 | if (file->f_op->llseek && file->f_op->llseek != no_llseek) { |
2272 | if (file->f_op->llseek(file, off, SEEK_CUR) < 0) |
2273 | return 0; |
2274 | } else { |
2275 | char *buf = (char *)get_zeroed_page(GFP_KERNEL); |
2276 | |
2277 | if (!buf) |
2278 | return 0; |
2279 | while (off > 0) { |
2280 | unsigned long n = off; |
2281 | |
2282 | if (n > PAGE_SIZE) |
2283 | n = PAGE_SIZE; |
2284 | if (!dump_write(file, buf, n)) { |
2285 | ret = 0; |
2286 | break; |
2287 | } |
2288 | off -= n; |
2289 | } |
2290 | free_page((unsigned long)buf); |
2291 | } |
2292 | return ret; |
2293 | } |
2294 | EXPORT_SYMBOL(dump_seek); |
2295 |
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