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Commit | Line | Data |
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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 | #include "coredump.h" | |
66 | ||
67 | #include <trace/events/sched.h> | |
68 | ||
69 | int suid_dumpable = 0; | |
70 | ||
71 | static LIST_HEAD(formats); | |
72 | static DEFINE_RWLOCK(binfmt_lock); | |
73 | ||
74 | void __register_binfmt(struct linux_binfmt * fmt, int insert) | |
75 | { | |
76 | BUG_ON(!fmt); | |
77 | write_lock(&binfmt_lock); | |
78 | insert ? list_add(&fmt->lh, &formats) : | |
79 | list_add_tail(&fmt->lh, &formats); | |
80 | write_unlock(&binfmt_lock); | |
81 | } | |
82 | ||
83 | EXPORT_SYMBOL(__register_binfmt); | |
84 | ||
85 | void unregister_binfmt(struct linux_binfmt * fmt) | |
86 | { | |
87 | write_lock(&binfmt_lock); | |
88 | list_del(&fmt->lh); | |
89 | write_unlock(&binfmt_lock); | |
90 | } | |
91 | ||
92 | EXPORT_SYMBOL(unregister_binfmt); | |
93 | ||
94 | static inline void put_binfmt(struct linux_binfmt * fmt) | |
95 | { | |
96 | module_put(fmt->module); | |
97 | } | |
98 | ||
99 | /* | |
100 | * Note that a shared library must be both readable and executable due to | |
101 | * security reasons. | |
102 | * | |
103 | * Also note that we take the address to load from from the file itself. | |
104 | */ | |
105 | SYSCALL_DEFINE1(uselib, const char __user *, library) | |
106 | { | |
107 | struct file *file; | |
108 | struct filename *tmp = getname(library); | |
109 | int error = PTR_ERR(tmp); | |
110 | static const struct open_flags uselib_flags = { | |
111 | .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, | |
112 | .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN, | |
113 | .intent = LOOKUP_OPEN, | |
114 | .lookup_flags = LOOKUP_FOLLOW, | |
115 | }; | |
116 | ||
117 | if (IS_ERR(tmp)) | |
118 | goto out; | |
119 | ||
120 | file = do_filp_open(AT_FDCWD, tmp, &uselib_flags); | |
121 | putname(tmp); | |
122 | error = PTR_ERR(file); | |
123 | if (IS_ERR(file)) | |
124 | goto out; | |
125 | ||
126 | error = -EINVAL; | |
127 | if (!S_ISREG(file_inode(file)->i_mode)) | |
128 | goto exit; | |
129 | ||
130 | error = -EACCES; | |
131 | if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) | |
132 | goto exit; | |
133 | ||
134 | fsnotify_open(file); | |
135 | ||
136 | error = -ENOEXEC; | |
137 | if(file->f_op) { | |
138 | struct linux_binfmt * fmt; | |
139 | ||
140 | read_lock(&binfmt_lock); | |
141 | list_for_each_entry(fmt, &formats, lh) { | |
142 | if (!fmt->load_shlib) | |
143 | continue; | |
144 | if (!try_module_get(fmt->module)) | |
145 | continue; | |
146 | read_unlock(&binfmt_lock); | |
147 | error = fmt->load_shlib(file); | |
148 | read_lock(&binfmt_lock); | |
149 | put_binfmt(fmt); | |
150 | if (error != -ENOEXEC) | |
151 | break; | |
152 | } | |
153 | read_unlock(&binfmt_lock); | |
154 | } | |
155 | exit: | |
156 | fput(file); | |
157 | out: | |
158 | return error; | |
159 | } | |
160 | ||
161 | #ifdef CONFIG_MMU | |
162 | /* | |
163 | * The nascent bprm->mm is not visible until exec_mmap() but it can | |
164 | * use a lot of memory, account these pages in current->mm temporary | |
165 | * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we | |
166 | * change the counter back via acct_arg_size(0). | |
167 | */ | |
168 | static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) | |
169 | { | |
170 | struct mm_struct *mm = current->mm; | |
171 | long diff = (long)(pages - bprm->vma_pages); | |
172 | ||
173 | if (!mm || !diff) | |
174 | return; | |
175 | ||
176 | bprm->vma_pages = pages; | |
177 | add_mm_counter(mm, MM_ANONPAGES, diff); | |
178 | } | |
179 | ||
180 | static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, | |
181 | int write) | |
182 | { | |
183 | struct page *page; | |
184 | int ret; | |
185 | ||
186 | #ifdef CONFIG_STACK_GROWSUP | |
187 | if (write) { | |
188 | ret = expand_downwards(bprm->vma, pos); | |
189 | if (ret < 0) | |
190 | return NULL; | |
191 | } | |
192 | #endif | |
193 | ret = get_user_pages(current, bprm->mm, pos, | |
194 | 1, write, 1, &page, NULL); | |
195 | if (ret <= 0) | |
196 | return NULL; | |
197 | ||
198 | if (write) { | |
199 | unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start; | |
200 | struct rlimit *rlim; | |
201 | ||
202 | acct_arg_size(bprm, size / PAGE_SIZE); | |
203 | ||
204 | /* | |
205 | * We've historically supported up to 32 pages (ARG_MAX) | |
206 | * of argument strings even with small stacks | |
207 | */ | |
208 | if (size <= ARG_MAX) | |
209 | return page; | |
210 | ||
211 | /* | |
212 | * Limit to 1/4-th the stack size for the argv+env strings. | |
213 | * This ensures that: | |
214 | * - the remaining binfmt code will not run out of stack space, | |
215 | * - the program will have a reasonable amount of stack left | |
216 | * to work from. | |
217 | */ | |
218 | rlim = current->signal->rlim; | |
219 | if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) { | |
220 | put_page(page); | |
221 | return NULL; | |
222 | } | |
223 | } | |
224 | ||
225 | return page; | |
226 | } | |
227 | ||
228 | static void put_arg_page(struct page *page) | |
229 | { | |
230 | put_page(page); | |
231 | } | |
232 | ||
233 | static void free_arg_page(struct linux_binprm *bprm, int i) | |
234 | { | |
235 | } | |
236 | ||
237 | static void free_arg_pages(struct linux_binprm *bprm) | |
238 | { | |
239 | } | |
240 | ||
241 | static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, | |
242 | struct page *page) | |
243 | { | |
244 | flush_cache_page(bprm->vma, pos, page_to_pfn(page)); | |
245 | } | |
246 | ||
247 | static int __bprm_mm_init(struct linux_binprm *bprm) | |
248 | { | |
249 | int err; | |
250 | struct vm_area_struct *vma = NULL; | |
251 | struct mm_struct *mm = bprm->mm; | |
252 | ||
253 | bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); | |
254 | if (!vma) | |
255 | return -ENOMEM; | |
256 | ||
257 | down_write(&mm->mmap_sem); | |
258 | vma->vm_mm = mm; | |
259 | ||
260 | /* | |
261 | * Place the stack at the largest stack address the architecture | |
262 | * supports. Later, we'll move this to an appropriate place. We don't | |
263 | * use STACK_TOP because that can depend on attributes which aren't | |
264 | * configured yet. | |
265 | */ | |
266 | BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP); | |
267 | vma->vm_end = STACK_TOP_MAX; | |
268 | vma->vm_start = vma->vm_end - PAGE_SIZE; | |
269 | vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP; | |
270 | vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); | |
271 | INIT_LIST_HEAD(&vma->anon_vma_chain); | |
272 | ||
273 | err = insert_vm_struct(mm, vma); | |
274 | if (err) | |
275 | goto err; | |
276 | ||
277 | mm->stack_vm = mm->total_vm = 1; | |
278 | up_write(&mm->mmap_sem); | |
279 | bprm->p = vma->vm_end - sizeof(void *); | |
280 | return 0; | |
281 | err: | |
282 | up_write(&mm->mmap_sem); | |
283 | bprm->vma = NULL; | |
284 | kmem_cache_free(vm_area_cachep, vma); | |
285 | return err; | |
286 | } | |
287 | ||
288 | static bool valid_arg_len(struct linux_binprm *bprm, long len) | |
289 | { | |
290 | return len <= MAX_ARG_STRLEN; | |
291 | } | |
292 | ||
293 | #else | |
294 | ||
295 | static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) | |
296 | { | |
297 | } | |
298 | ||
299 | static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, | |
300 | int write) | |
301 | { | |
302 | struct page *page; | |
303 | ||
304 | page = bprm->page[pos / PAGE_SIZE]; | |
305 | if (!page && write) { | |
306 | page = alloc_page(GFP_HIGHUSER|__GFP_ZERO); | |
307 | if (!page) | |
308 | return NULL; | |
309 | bprm->page[pos / PAGE_SIZE] = page; | |
310 | } | |
311 | ||
312 | return page; | |
313 | } | |
314 | ||
315 | static void put_arg_page(struct page *page) | |
316 | { | |
317 | } | |
318 | ||
319 | static void free_arg_page(struct linux_binprm *bprm, int i) | |
320 | { | |
321 | if (bprm->page[i]) { | |
322 | __free_page(bprm->page[i]); | |
323 | bprm->page[i] = NULL; | |
324 | } | |
325 | } | |
326 | ||
327 | static void free_arg_pages(struct linux_binprm *bprm) | |
328 | { | |
329 | int i; | |
330 | ||
331 | for (i = 0; i < MAX_ARG_PAGES; i++) | |
332 | free_arg_page(bprm, i); | |
333 | } | |
334 | ||
335 | static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, | |
336 | struct page *page) | |
337 | { | |
338 | } | |
339 | ||
340 | static int __bprm_mm_init(struct linux_binprm *bprm) | |
341 | { | |
342 | bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *); | |
343 | return 0; | |
344 | } | |
345 | ||
346 | static bool valid_arg_len(struct linux_binprm *bprm, long len) | |
347 | { | |
348 | return len <= bprm->p; | |
349 | } | |
350 | ||
351 | #endif /* CONFIG_MMU */ | |
352 | ||
353 | /* | |
354 | * Create a new mm_struct and populate it with a temporary stack | |
355 | * vm_area_struct. We don't have enough context at this point to set the stack | |
356 | * flags, permissions, and offset, so we use temporary values. We'll update | |
357 | * them later in setup_arg_pages(). | |
358 | */ | |
359 | static int bprm_mm_init(struct linux_binprm *bprm) | |
360 | { | |
361 | int err; | |
362 | struct mm_struct *mm = NULL; | |
363 | ||
364 | bprm->mm = mm = mm_alloc(); | |
365 | err = -ENOMEM; | |
366 | if (!mm) | |
367 | goto err; | |
368 | ||
369 | err = init_new_context(current, mm); | |
370 | if (err) | |
371 | goto err; | |
372 | ||
373 | err = __bprm_mm_init(bprm); | |
374 | if (err) | |
375 | goto err; | |
376 | ||
377 | return 0; | |
378 | ||
379 | err: | |
380 | if (mm) { | |
381 | bprm->mm = NULL; | |
382 | mmdrop(mm); | |
383 | } | |
384 | ||
385 | return err; | |
386 | } | |
387 | ||
388 | struct user_arg_ptr { | |
389 | #ifdef CONFIG_COMPAT | |
390 | bool is_compat; | |
391 | #endif | |
392 | union { | |
393 | const char __user *const __user *native; | |
394 | #ifdef CONFIG_COMPAT | |
395 | const compat_uptr_t __user *compat; | |
396 | #endif | |
397 | } ptr; | |
398 | }; | |
399 | ||
400 | static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr) | |
401 | { | |
402 | const char __user *native; | |
403 | ||
404 | #ifdef CONFIG_COMPAT | |
405 | if (unlikely(argv.is_compat)) { | |
406 | compat_uptr_t compat; | |
407 | ||
408 | if (get_user(compat, argv.ptr.compat + nr)) | |
409 | return ERR_PTR(-EFAULT); | |
410 | ||
411 | return compat_ptr(compat); | |
412 | } | |
413 | #endif | |
414 | ||
415 | if (get_user(native, argv.ptr.native + nr)) | |
416 | return ERR_PTR(-EFAULT); | |
417 | ||
418 | return native; | |
419 | } | |
420 | ||
421 | /* | |
422 | * count() counts the number of strings in array ARGV. | |
423 | */ | |
424 | static int count(struct user_arg_ptr argv, int max) | |
425 | { | |
426 | int i = 0; | |
427 | ||
428 | if (argv.ptr.native != NULL) { | |
429 | for (;;) { | |
430 | const char __user *p = get_user_arg_ptr(argv, i); | |
431 | ||
432 | if (!p) | |
433 | break; | |
434 | ||
435 | if (IS_ERR(p)) | |
436 | return -EFAULT; | |
437 | ||
438 | if (i >= max) | |
439 | return -E2BIG; | |
440 | ++i; | |
441 | ||
442 | if (fatal_signal_pending(current)) | |
443 | return -ERESTARTNOHAND; | |
444 | cond_resched(); | |
445 | } | |
446 | } | |
447 | return i; | |
448 | } | |
449 | ||
450 | /* | |
451 | * 'copy_strings()' copies argument/environment strings from the old | |
452 | * processes's memory to the new process's stack. The call to get_user_pages() | |
453 | * ensures the destination page is created and not swapped out. | |
454 | */ | |
455 | static int copy_strings(int argc, struct user_arg_ptr argv, | |
456 | struct linux_binprm *bprm) | |
457 | { | |
458 | struct page *kmapped_page = NULL; | |
459 | char *kaddr = NULL; | |
460 | unsigned long kpos = 0; | |
461 | int ret; | |
462 | ||
463 | while (argc-- > 0) { | |
464 | const char __user *str; | |
465 | int len; | |
466 | unsigned long pos; | |
467 | ||
468 | ret = -EFAULT; | |
469 | str = get_user_arg_ptr(argv, argc); | |
470 | if (IS_ERR(str)) | |
471 | goto out; | |
472 | ||
473 | len = strnlen_user(str, MAX_ARG_STRLEN); | |
474 | if (!len) | |
475 | goto out; | |
476 | ||
477 | ret = -E2BIG; | |
478 | if (!valid_arg_len(bprm, len)) | |
479 | goto out; | |
480 | ||
481 | /* We're going to work our way backwords. */ | |
482 | pos = bprm->p; | |
483 | str += len; | |
484 | bprm->p -= len; | |
485 | ||
486 | while (len > 0) { | |
487 | int offset, bytes_to_copy; | |
488 | ||
489 | if (fatal_signal_pending(current)) { | |
490 | ret = -ERESTARTNOHAND; | |
491 | goto out; | |
492 | } | |
493 | cond_resched(); | |
494 | ||
495 | offset = pos % PAGE_SIZE; | |
496 | if (offset == 0) | |
497 | offset = PAGE_SIZE; | |
498 | ||
499 | bytes_to_copy = offset; | |
500 | if (bytes_to_copy > len) | |
501 | bytes_to_copy = len; | |
502 | ||
503 | offset -= bytes_to_copy; | |
504 | pos -= bytes_to_copy; | |
505 | str -= bytes_to_copy; | |
506 | len -= bytes_to_copy; | |
507 | ||
508 | if (!kmapped_page || kpos != (pos & PAGE_MASK)) { | |
509 | struct page *page; | |
510 | ||
511 | page = get_arg_page(bprm, pos, 1); | |
512 | if (!page) { | |
513 | ret = -E2BIG; | |
514 | goto out; | |
515 | } | |
516 | ||
517 | if (kmapped_page) { | |
518 | flush_kernel_dcache_page(kmapped_page); | |
519 | kunmap(kmapped_page); | |
520 | put_arg_page(kmapped_page); | |
521 | } | |
522 | kmapped_page = page; | |
523 | kaddr = kmap(kmapped_page); | |
524 | kpos = pos & PAGE_MASK; | |
525 | flush_arg_page(bprm, kpos, kmapped_page); | |
526 | } | |
527 | if (copy_from_user(kaddr+offset, str, bytes_to_copy)) { | |
528 | ret = -EFAULT; | |
529 | goto out; | |
530 | } | |
531 | } | |
532 | } | |
533 | ret = 0; | |
534 | out: | |
535 | if (kmapped_page) { | |
536 | flush_kernel_dcache_page(kmapped_page); | |
537 | kunmap(kmapped_page); | |
538 | put_arg_page(kmapped_page); | |
539 | } | |
540 | return ret; | |
541 | } | |
542 | ||
543 | /* | |
544 | * Like copy_strings, but get argv and its values from kernel memory. | |
545 | */ | |
546 | int copy_strings_kernel(int argc, const char *const *__argv, | |
547 | struct linux_binprm *bprm) | |
548 | { | |
549 | int r; | |
550 | mm_segment_t oldfs = get_fs(); | |
551 | struct user_arg_ptr argv = { | |
552 | .ptr.native = (const char __user *const __user *)__argv, | |
553 | }; | |
554 | ||
555 | set_fs(KERNEL_DS); | |
556 | r = copy_strings(argc, argv, bprm); | |
557 | set_fs(oldfs); | |
558 | ||
559 | return r; | |
560 | } | |
561 | EXPORT_SYMBOL(copy_strings_kernel); | |
562 | ||
563 | #ifdef CONFIG_MMU | |
564 | ||
565 | /* | |
566 | * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once | |
567 | * the binfmt code determines where the new stack should reside, we shift it to | |
568 | * its final location. The process proceeds as follows: | |
569 | * | |
570 | * 1) Use shift to calculate the new vma endpoints. | |
571 | * 2) Extend vma to cover both the old and new ranges. This ensures the | |
572 | * arguments passed to subsequent functions are consistent. | |
573 | * 3) Move vma's page tables to the new range. | |
574 | * 4) Free up any cleared pgd range. | |
575 | * 5) Shrink the vma to cover only the new range. | |
576 | */ | |
577 | static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift) | |
578 | { | |
579 | struct mm_struct *mm = vma->vm_mm; | |
580 | unsigned long old_start = vma->vm_start; | |
581 | unsigned long old_end = vma->vm_end; | |
582 | unsigned long length = old_end - old_start; | |
583 | unsigned long new_start = old_start - shift; | |
584 | unsigned long new_end = old_end - shift; | |
585 | struct mmu_gather tlb; | |
586 | ||
587 | BUG_ON(new_start > new_end); | |
588 | ||
589 | /* | |
590 | * ensure there are no vmas between where we want to go | |
591 | * and where we are | |
592 | */ | |
593 | if (vma != find_vma(mm, new_start)) | |
594 | return -EFAULT; | |
595 | ||
596 | /* | |
597 | * cover the whole range: [new_start, old_end) | |
598 | */ | |
599 | if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL)) | |
600 | return -ENOMEM; | |
601 | ||
602 | /* | |
603 | * move the page tables downwards, on failure we rely on | |
604 | * process cleanup to remove whatever mess we made. | |
605 | */ | |
606 | if (length != move_page_tables(vma, old_start, | |
607 | vma, new_start, length, false)) | |
608 | return -ENOMEM; | |
609 | ||
610 | lru_add_drain(); | |
611 | tlb_gather_mmu(&tlb, mm, old_start, old_end); | |
612 | if (new_end > old_start) { | |
613 | /* | |
614 | * when the old and new regions overlap clear from new_end. | |
615 | */ | |
616 | free_pgd_range(&tlb, new_end, old_end, new_end, | |
617 | vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING); | |
618 | } else { | |
619 | /* | |
620 | * otherwise, clean from old_start; this is done to not touch | |
621 | * the address space in [new_end, old_start) some architectures | |
622 | * have constraints on va-space that make this illegal (IA64) - | |
623 | * for the others its just a little faster. | |
624 | */ | |
625 | free_pgd_range(&tlb, old_start, old_end, new_end, | |
626 | vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING); | |
627 | } | |
628 | tlb_finish_mmu(&tlb, old_start, old_end); | |
629 | ||
630 | /* | |
631 | * Shrink the vma to just the new range. Always succeeds. | |
632 | */ | |
633 | vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL); | |
634 | ||
635 | return 0; | |
636 | } | |
637 | ||
638 | /* | |
639 | * Finalizes the stack vm_area_struct. The flags and permissions are updated, | |
640 | * the stack is optionally relocated, and some extra space is added. | |
641 | */ | |
642 | int setup_arg_pages(struct linux_binprm *bprm, | |
643 | unsigned long stack_top, | |
644 | int executable_stack) | |
645 | { | |
646 | unsigned long ret; | |
647 | unsigned long stack_shift; | |
648 | struct mm_struct *mm = current->mm; | |
649 | struct vm_area_struct *vma = bprm->vma; | |
650 | struct vm_area_struct *prev = NULL; | |
651 | unsigned long vm_flags; | |
652 | unsigned long stack_base; | |
653 | unsigned long stack_size; | |
654 | unsigned long stack_expand; | |
655 | unsigned long rlim_stack; | |
656 | ||
657 | #ifdef CONFIG_STACK_GROWSUP | |
658 | /* Limit stack size to 1GB */ | |
659 | stack_base = rlimit_max(RLIMIT_STACK); | |
660 | if (stack_base > (1 << 30)) | |
661 | stack_base = 1 << 30; | |
662 | ||
663 | /* Make sure we didn't let the argument array grow too large. */ | |
664 | if (vma->vm_end - vma->vm_start > stack_base) | |
665 | return -ENOMEM; | |
666 | ||
667 | stack_base = PAGE_ALIGN(stack_top - stack_base); | |
668 | ||
669 | stack_shift = vma->vm_start - stack_base; | |
670 | mm->arg_start = bprm->p - stack_shift; | |
671 | bprm->p = vma->vm_end - stack_shift; | |
672 | #else | |
673 | stack_top = arch_align_stack(stack_top); | |
674 | stack_top = PAGE_ALIGN(stack_top); | |
675 | ||
676 | if (unlikely(stack_top < mmap_min_addr) || | |
677 | unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr)) | |
678 | return -ENOMEM; | |
679 | ||
680 | stack_shift = vma->vm_end - stack_top; | |
681 | ||
682 | bprm->p -= stack_shift; | |
683 | mm->arg_start = bprm->p; | |
684 | #endif | |
685 | ||
686 | if (bprm->loader) | |
687 | bprm->loader -= stack_shift; | |
688 | bprm->exec -= stack_shift; | |
689 | ||
690 | down_write(&mm->mmap_sem); | |
691 | vm_flags = VM_STACK_FLAGS; | |
692 | ||
693 | /* | |
694 | * Adjust stack execute permissions; explicitly enable for | |
695 | * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone | |
696 | * (arch default) otherwise. | |
697 | */ | |
698 | if (unlikely(executable_stack == EXSTACK_ENABLE_X)) | |
699 | vm_flags |= VM_EXEC; | |
700 | else if (executable_stack == EXSTACK_DISABLE_X) | |
701 | vm_flags &= ~VM_EXEC; | |
702 | vm_flags |= mm->def_flags; | |
703 | vm_flags |= VM_STACK_INCOMPLETE_SETUP; | |
704 | ||
705 | ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end, | |
706 | vm_flags); | |
707 | if (ret) | |
708 | goto out_unlock; | |
709 | BUG_ON(prev != vma); | |
710 | ||
711 | /* Move stack pages down in memory. */ | |
712 | if (stack_shift) { | |
713 | ret = shift_arg_pages(vma, stack_shift); | |
714 | if (ret) | |
715 | goto out_unlock; | |
716 | } | |
717 | ||
718 | /* mprotect_fixup is overkill to remove the temporary stack flags */ | |
719 | vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP; | |
720 | ||
721 | stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */ | |
722 | stack_size = vma->vm_end - vma->vm_start; | |
723 | /* | |
724 | * Align this down to a page boundary as expand_stack | |
725 | * will align it up. | |
726 | */ | |
727 | rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK; | |
728 | #ifdef CONFIG_STACK_GROWSUP | |
729 | if (stack_size + stack_expand > rlim_stack) | |
730 | stack_base = vma->vm_start + rlim_stack; | |
731 | else | |
732 | stack_base = vma->vm_end + stack_expand; | |
733 | #else | |
734 | if (stack_size + stack_expand > rlim_stack) | |
735 | stack_base = vma->vm_end - rlim_stack; | |
736 | else | |
737 | stack_base = vma->vm_start - stack_expand; | |
738 | #endif | |
739 | current->mm->start_stack = bprm->p; | |
740 | ret = expand_stack(vma, stack_base); | |
741 | if (ret) | |
742 | ret = -EFAULT; | |
743 | ||
744 | out_unlock: | |
745 | up_write(&mm->mmap_sem); | |
746 | return ret; | |
747 | } | |
748 | EXPORT_SYMBOL(setup_arg_pages); | |
749 | ||
750 | #endif /* CONFIG_MMU */ | |
751 | ||
752 | struct file *open_exec(const char *name) | |
753 | { | |
754 | struct file *file; | |
755 | int err; | |
756 | struct filename tmp = { .name = name }; | |
757 | static const struct open_flags open_exec_flags = { | |
758 | .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, | |
759 | .acc_mode = MAY_EXEC | MAY_OPEN, | |
760 | .intent = LOOKUP_OPEN, | |
761 | .lookup_flags = LOOKUP_FOLLOW, | |
762 | }; | |
763 | ||
764 | file = do_filp_open(AT_FDCWD, &tmp, &open_exec_flags); | |
765 | if (IS_ERR(file)) | |
766 | goto out; | |
767 | ||
768 | err = -EACCES; | |
769 | if (!S_ISREG(file_inode(file)->i_mode)) | |
770 | goto exit; | |
771 | ||
772 | if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) | |
773 | goto exit; | |
774 | ||
775 | fsnotify_open(file); | |
776 | ||
777 | err = deny_write_access(file); | |
778 | if (err) | |
779 | goto exit; | |
780 | ||
781 | out: | |
782 | return file; | |
783 | ||
784 | exit: | |
785 | fput(file); | |
786 | return ERR_PTR(err); | |
787 | } | |
788 | EXPORT_SYMBOL(open_exec); | |
789 | ||
790 | int kernel_read(struct file *file, loff_t offset, | |
791 | char *addr, unsigned long count) | |
792 | { | |
793 | mm_segment_t old_fs; | |
794 | loff_t pos = offset; | |
795 | int result; | |
796 | ||
797 | old_fs = get_fs(); | |
798 | set_fs(get_ds()); | |
799 | /* The cast to a user pointer is valid due to the set_fs() */ | |
800 | result = vfs_read(file, (void __user *)addr, count, &pos); | |
801 | set_fs(old_fs); | |
802 | return result; | |
803 | } | |
804 | ||
805 | EXPORT_SYMBOL(kernel_read); | |
806 | ||
807 | ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len) | |
808 | { | |
809 | ssize_t res = file->f_op->read(file, (void __user *)addr, len, &pos); | |
810 | if (res > 0) | |
811 | flush_icache_range(addr, addr + len); | |
812 | return res; | |
813 | } | |
814 | EXPORT_SYMBOL(read_code); | |
815 | ||
816 | static int exec_mmap(struct mm_struct *mm) | |
817 | { | |
818 | struct task_struct *tsk; | |
819 | struct mm_struct * old_mm, *active_mm; | |
820 | ||
821 | /* Notify parent that we're no longer interested in the old VM */ | |
822 | tsk = current; | |
823 | old_mm = current->mm; | |
824 | mm_release(tsk, old_mm); | |
825 | ||
826 | if (old_mm) { | |
827 | sync_mm_rss(old_mm); | |
828 | /* | |
829 | * Make sure that if there is a core dump in progress | |
830 | * for the old mm, we get out and die instead of going | |
831 | * through with the exec. We must hold mmap_sem around | |
832 | * checking core_state and changing tsk->mm. | |
833 | */ | |
834 | down_read(&old_mm->mmap_sem); | |
835 | if (unlikely(old_mm->core_state)) { | |
836 | up_read(&old_mm->mmap_sem); | |
837 | return -EINTR; | |
838 | } | |
839 | } | |
840 | task_lock(tsk); | |
841 | active_mm = tsk->active_mm; | |
842 | tsk->mm = mm; | |
843 | tsk->active_mm = mm; | |
844 | activate_mm(active_mm, mm); | |
845 | task_unlock(tsk); | |
846 | arch_pick_mmap_layout(mm); | |
847 | if (old_mm) { | |
848 | up_read(&old_mm->mmap_sem); | |
849 | BUG_ON(active_mm != old_mm); | |
850 | setmax_mm_hiwater_rss(&tsk->signal->maxrss, 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_KILLABLE); | |
894 | spin_unlock_irq(lock); | |
895 | schedule(); | |
896 | if (unlikely(__fatal_signal_pending(tsk))) | |
897 | goto killed; | |
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 | threadgroup_change_begin(tsk); | |
913 | write_lock_irq(&tasklist_lock); | |
914 | if (likely(leader->exit_state)) | |
915 | break; | |
916 | __set_current_state(TASK_KILLABLE); | |
917 | write_unlock_irq(&tasklist_lock); | |
918 | threadgroup_change_end(tsk); | |
919 | schedule(); | |
920 | if (unlikely(__fatal_signal_pending(tsk))) | |
921 | goto killed; | |
922 | } | |
923 | ||
924 | /* | |
925 | * The only record we have of the real-time age of a | |
926 | * process, regardless of execs it's done, is start_time. | |
927 | * All the past CPU time is accumulated in signal_struct | |
928 | * from sister threads now dead. But in this non-leader | |
929 | * exec, nothing survives from the original leader thread, | |
930 | * whose birth marks the true age of this process now. | |
931 | * When we take on its identity by switching to its PID, we | |
932 | * also take its birthdate (always earlier than our own). | |
933 | */ | |
934 | tsk->start_time = leader->start_time; | |
935 | tsk->real_start_time = leader->real_start_time; | |
936 | ||
937 | BUG_ON(!same_thread_group(leader, tsk)); | |
938 | BUG_ON(has_group_leader_pid(tsk)); | |
939 | /* | |
940 | * An exec() starts a new thread group with the | |
941 | * TGID of the previous thread group. Rehash the | |
942 | * two threads with a switched PID, and release | |
943 | * the former thread group leader: | |
944 | */ | |
945 | ||
946 | /* Become a process group leader with the old leader's pid. | |
947 | * The old leader becomes a thread of the this thread group. | |
948 | * Note: The old leader also uses this pid until release_task | |
949 | * is called. Odd but simple and correct. | |
950 | */ | |
951 | tsk->pid = leader->pid; | |
952 | change_pid(tsk, PIDTYPE_PID, task_pid(leader)); | |
953 | transfer_pid(leader, tsk, PIDTYPE_PGID); | |
954 | transfer_pid(leader, tsk, PIDTYPE_SID); | |
955 | ||
956 | list_replace_rcu(&leader->tasks, &tsk->tasks); | |
957 | list_replace_init(&leader->sibling, &tsk->sibling); | |
958 | ||
959 | tsk->group_leader = tsk; | |
960 | leader->group_leader = tsk; | |
961 | ||
962 | tsk->exit_signal = SIGCHLD; | |
963 | leader->exit_signal = -1; | |
964 | ||
965 | BUG_ON(leader->exit_state != EXIT_ZOMBIE); | |
966 | leader->exit_state = EXIT_DEAD; | |
967 | ||
968 | /* | |
969 | * We are going to release_task()->ptrace_unlink() silently, | |
970 | * the tracer can sleep in do_wait(). EXIT_DEAD guarantees | |
971 | * the tracer wont't block again waiting for this thread. | |
972 | */ | |
973 | if (unlikely(leader->ptrace)) | |
974 | __wake_up_parent(leader, leader->parent); | |
975 | write_unlock_irq(&tasklist_lock); | |
976 | threadgroup_change_end(tsk); | |
977 | ||
978 | release_task(leader); | |
979 | } | |
980 | ||
981 | sig->group_exit_task = NULL; | |
982 | sig->notify_count = 0; | |
983 | ||
984 | no_thread_group: | |
985 | /* we have changed execution domain */ | |
986 | tsk->exit_signal = SIGCHLD; | |
987 | ||
988 | exit_itimers(sig); | |
989 | flush_itimer_signals(); | |
990 | ||
991 | if (atomic_read(&oldsighand->count) != 1) { | |
992 | struct sighand_struct *newsighand; | |
993 | /* | |
994 | * This ->sighand is shared with the CLONE_SIGHAND | |
995 | * but not CLONE_THREAD task, switch to the new one. | |
996 | */ | |
997 | newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); | |
998 | if (!newsighand) | |
999 | return -ENOMEM; | |
1000 | ||
1001 | atomic_set(&newsighand->count, 1); | |
1002 | memcpy(newsighand->action, oldsighand->action, | |
1003 | sizeof(newsighand->action)); | |
1004 | ||
1005 | write_lock_irq(&tasklist_lock); | |
1006 | spin_lock(&oldsighand->siglock); | |
1007 | rcu_assign_pointer(tsk->sighand, newsighand); | |
1008 | spin_unlock(&oldsighand->siglock); | |
1009 | write_unlock_irq(&tasklist_lock); | |
1010 | ||
1011 | __cleanup_sighand(oldsighand); | |
1012 | } | |
1013 | ||
1014 | BUG_ON(!thread_group_leader(tsk)); | |
1015 | return 0; | |
1016 | ||
1017 | killed: | |
1018 | /* protects against exit_notify() and __exit_signal() */ | |
1019 | read_lock(&tasklist_lock); | |
1020 | sig->group_exit_task = NULL; | |
1021 | sig->notify_count = 0; | |
1022 | read_unlock(&tasklist_lock); | |
1023 | return -EAGAIN; | |
1024 | } | |
1025 | ||
1026 | char *get_task_comm(char *buf, struct task_struct *tsk) | |
1027 | { | |
1028 | /* buf must be at least sizeof(tsk->comm) in size */ | |
1029 | task_lock(tsk); | |
1030 | strncpy(buf, tsk->comm, sizeof(tsk->comm)); | |
1031 | task_unlock(tsk); | |
1032 | return buf; | |
1033 | } | |
1034 | EXPORT_SYMBOL_GPL(get_task_comm); | |
1035 | ||
1036 | /* | |
1037 | * These functions flushes out all traces of the currently running executable | |
1038 | * so that a new one can be started | |
1039 | */ | |
1040 | ||
1041 | void set_task_comm(struct task_struct *tsk, char *buf) | |
1042 | { | |
1043 | task_lock(tsk); | |
1044 | trace_task_rename(tsk, buf); | |
1045 | strlcpy(tsk->comm, buf, sizeof(tsk->comm)); | |
1046 | task_unlock(tsk); | |
1047 | perf_event_comm(tsk); | |
1048 | } | |
1049 | ||
1050 | static void filename_to_taskname(char *tcomm, const char *fn, unsigned int len) | |
1051 | { | |
1052 | int i, ch; | |
1053 | ||
1054 | /* Copies the binary name from after last slash */ | |
1055 | for (i = 0; (ch = *(fn++)) != '\0';) { | |
1056 | if (ch == '/') | |
1057 | i = 0; /* overwrite what we wrote */ | |
1058 | else | |
1059 | if (i < len - 1) | |
1060 | tcomm[i++] = ch; | |
1061 | } | |
1062 | tcomm[i] = '\0'; | |
1063 | } | |
1064 | ||
1065 | int flush_old_exec(struct linux_binprm * bprm) | |
1066 | { | |
1067 | int retval; | |
1068 | ||
1069 | /* | |
1070 | * Make sure we have a private signal table and that | |
1071 | * we are unassociated from the previous thread group. | |
1072 | */ | |
1073 | retval = de_thread(current); | |
1074 | if (retval) | |
1075 | goto out; | |
1076 | ||
1077 | set_mm_exe_file(bprm->mm, bprm->file); | |
1078 | ||
1079 | filename_to_taskname(bprm->tcomm, bprm->filename, sizeof(bprm->tcomm)); | |
1080 | /* | |
1081 | * Release all of the old mmap stuff | |
1082 | */ | |
1083 | acct_arg_size(bprm, 0); | |
1084 | retval = exec_mmap(bprm->mm); | |
1085 | if (retval) | |
1086 | goto out; | |
1087 | ||
1088 | bprm->mm = NULL; /* We're using it now */ | |
1089 | ||
1090 | set_fs(USER_DS); | |
1091 | current->flags &= | |
1092 | ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | PF_NOFREEZE); | |
1093 | flush_thread(); | |
1094 | current->personality &= ~bprm->per_clear; | |
1095 | ||
1096 | return 0; | |
1097 | ||
1098 | out: | |
1099 | return retval; | |
1100 | } | |
1101 | EXPORT_SYMBOL(flush_old_exec); | |
1102 | ||
1103 | void would_dump(struct linux_binprm *bprm, struct file *file) | |
1104 | { | |
1105 | if (inode_permission(file_inode(file), MAY_READ) < 0) | |
1106 | bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP; | |
1107 | } | |
1108 | EXPORT_SYMBOL(would_dump); | |
1109 | ||
1110 | void setup_new_exec(struct linux_binprm * bprm) | |
1111 | { | |
1112 | arch_pick_mmap_layout(current->mm); | |
1113 | ||
1114 | /* This is the point of no return */ | |
1115 | current->sas_ss_sp = current->sas_ss_size = 0; | |
1116 | ||
1117 | if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid())) | |
1118 | set_dumpable(current->mm, SUID_DUMP_USER); | |
1119 | else | |
1120 | set_dumpable(current->mm, suid_dumpable); | |
1121 | ||
1122 | set_task_comm(current, bprm->tcomm); | |
1123 | ||
1124 | /* Set the new mm task size. We have to do that late because it may | |
1125 | * depend on TIF_32BIT which is only updated in flush_thread() on | |
1126 | * some architectures like powerpc | |
1127 | */ | |
1128 | current->mm->task_size = TASK_SIZE; | |
1129 | ||
1130 | /* install the new credentials */ | |
1131 | if (!uid_eq(bprm->cred->uid, current_euid()) || | |
1132 | !gid_eq(bprm->cred->gid, current_egid())) { | |
1133 | current->pdeath_signal = 0; | |
1134 | } else { | |
1135 | would_dump(bprm, bprm->file); | |
1136 | if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) | |
1137 | set_dumpable(current->mm, suid_dumpable); | |
1138 | } | |
1139 | ||
1140 | /* An exec changes our domain. We are no longer part of the thread | |
1141 | group */ | |
1142 | ||
1143 | current->self_exec_id++; | |
1144 | ||
1145 | flush_signal_handlers(current, 0); | |
1146 | do_close_on_exec(current->files); | |
1147 | } | |
1148 | EXPORT_SYMBOL(setup_new_exec); | |
1149 | ||
1150 | /* | |
1151 | * Prepare credentials and lock ->cred_guard_mutex. | |
1152 | * install_exec_creds() commits the new creds and drops the lock. | |
1153 | * Or, if exec fails before, free_bprm() should release ->cred and | |
1154 | * and unlock. | |
1155 | */ | |
1156 | int prepare_bprm_creds(struct linux_binprm *bprm) | |
1157 | { | |
1158 | if (mutex_lock_interruptible(¤t->signal->cred_guard_mutex)) | |
1159 | return -ERESTARTNOINTR; | |
1160 | ||
1161 | bprm->cred = prepare_exec_creds(); | |
1162 | if (likely(bprm->cred)) | |
1163 | return 0; | |
1164 | ||
1165 | mutex_unlock(¤t->signal->cred_guard_mutex); | |
1166 | return -ENOMEM; | |
1167 | } | |
1168 | ||
1169 | void free_bprm(struct linux_binprm *bprm) | |
1170 | { | |
1171 | free_arg_pages(bprm); | |
1172 | if (bprm->cred) { | |
1173 | mutex_unlock(¤t->signal->cred_guard_mutex); | |
1174 | abort_creds(bprm->cred); | |
1175 | } | |
1176 | /* If a binfmt changed the interp, free it. */ | |
1177 | if (bprm->interp != bprm->filename) | |
1178 | kfree(bprm->interp); | |
1179 | kfree(bprm); | |
1180 | } | |
1181 | ||
1182 | int bprm_change_interp(char *interp, struct linux_binprm *bprm) | |
1183 | { | |
1184 | /* If a binfmt changed the interp, free it first. */ | |
1185 | if (bprm->interp != bprm->filename) | |
1186 | kfree(bprm->interp); | |
1187 | bprm->interp = kstrdup(interp, GFP_KERNEL); | |
1188 | if (!bprm->interp) | |
1189 | return -ENOMEM; | |
1190 | return 0; | |
1191 | } | |
1192 | EXPORT_SYMBOL(bprm_change_interp); | |
1193 | ||
1194 | /* | |
1195 | * install the new credentials for this executable | |
1196 | */ | |
1197 | void install_exec_creds(struct linux_binprm *bprm) | |
1198 | { | |
1199 | security_bprm_committing_creds(bprm); | |
1200 | ||
1201 | commit_creds(bprm->cred); | |
1202 | bprm->cred = NULL; | |
1203 | ||
1204 | /* | |
1205 | * Disable monitoring for regular users | |
1206 | * when executing setuid binaries. Must | |
1207 | * wait until new credentials are committed | |
1208 | * by commit_creds() above | |
1209 | */ | |
1210 | if (get_dumpable(current->mm) != SUID_DUMP_USER) | |
1211 | perf_event_exit_task(current); | |
1212 | /* | |
1213 | * cred_guard_mutex must be held at least to this point to prevent | |
1214 | * ptrace_attach() from altering our determination of the task's | |
1215 | * credentials; any time after this it may be unlocked. | |
1216 | */ | |
1217 | security_bprm_committed_creds(bprm); | |
1218 | mutex_unlock(¤t->signal->cred_guard_mutex); | |
1219 | } | |
1220 | EXPORT_SYMBOL(install_exec_creds); | |
1221 | ||
1222 | /* | |
1223 | * determine how safe it is to execute the proposed program | |
1224 | * - the caller must hold ->cred_guard_mutex to protect against | |
1225 | * PTRACE_ATTACH | |
1226 | */ | |
1227 | static int check_unsafe_exec(struct linux_binprm *bprm) | |
1228 | { | |
1229 | struct task_struct *p = current, *t; | |
1230 | unsigned n_fs; | |
1231 | int res = 0; | |
1232 | ||
1233 | if (p->ptrace) { | |
1234 | if (p->ptrace & PT_PTRACE_CAP) | |
1235 | bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP; | |
1236 | else | |
1237 | bprm->unsafe |= LSM_UNSAFE_PTRACE; | |
1238 | } | |
1239 | ||
1240 | /* | |
1241 | * This isn't strictly necessary, but it makes it harder for LSMs to | |
1242 | * mess up. | |
1243 | */ | |
1244 | if (current->no_new_privs) | |
1245 | bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS; | |
1246 | ||
1247 | n_fs = 1; | |
1248 | spin_lock(&p->fs->lock); | |
1249 | rcu_read_lock(); | |
1250 | for (t = next_thread(p); t != p; t = next_thread(t)) { | |
1251 | if (t->fs == p->fs) | |
1252 | n_fs++; | |
1253 | } | |
1254 | rcu_read_unlock(); | |
1255 | ||
1256 | if (p->fs->users > n_fs) { | |
1257 | bprm->unsafe |= LSM_UNSAFE_SHARE; | |
1258 | } else { | |
1259 | res = -EAGAIN; | |
1260 | if (!p->fs->in_exec) { | |
1261 | p->fs->in_exec = 1; | |
1262 | res = 1; | |
1263 | } | |
1264 | } | |
1265 | spin_unlock(&p->fs->lock); | |
1266 | ||
1267 | return res; | |
1268 | } | |
1269 | ||
1270 | /* | |
1271 | * Fill the binprm structure from the inode. | |
1272 | * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes | |
1273 | * | |
1274 | * This may be called multiple times for binary chains (scripts for example). | |
1275 | */ | |
1276 | int prepare_binprm(struct linux_binprm *bprm) | |
1277 | { | |
1278 | umode_t mode; | |
1279 | struct inode * inode = file_inode(bprm->file); | |
1280 | int retval; | |
1281 | ||
1282 | mode = inode->i_mode; | |
1283 | if (bprm->file->f_op == NULL) | |
1284 | return -EACCES; | |
1285 | ||
1286 | /* clear any previous set[ug]id data from a previous binary */ | |
1287 | bprm->cred->euid = current_euid(); | |
1288 | bprm->cred->egid = current_egid(); | |
1289 | ||
1290 | if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) && | |
1291 | !current->no_new_privs && | |
1292 | kuid_has_mapping(bprm->cred->user_ns, inode->i_uid) && | |
1293 | kgid_has_mapping(bprm->cred->user_ns, inode->i_gid)) { | |
1294 | /* Set-uid? */ | |
1295 | if (mode & S_ISUID) { | |
1296 | bprm->per_clear |= PER_CLEAR_ON_SETID; | |
1297 | bprm->cred->euid = inode->i_uid; | |
1298 | } | |
1299 | ||
1300 | /* Set-gid? */ | |
1301 | /* | |
1302 | * If setgid is set but no group execute bit then this | |
1303 | * is a candidate for mandatory locking, not a setgid | |
1304 | * executable. | |
1305 | */ | |
1306 | if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { | |
1307 | bprm->per_clear |= PER_CLEAR_ON_SETID; | |
1308 | bprm->cred->egid = inode->i_gid; | |
1309 | } | |
1310 | } | |
1311 | ||
1312 | /* fill in binprm security blob */ | |
1313 | retval = security_bprm_set_creds(bprm); | |
1314 | if (retval) | |
1315 | return retval; | |
1316 | bprm->cred_prepared = 1; | |
1317 | ||
1318 | memset(bprm->buf, 0, BINPRM_BUF_SIZE); | |
1319 | return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE); | |
1320 | } | |
1321 | ||
1322 | EXPORT_SYMBOL(prepare_binprm); | |
1323 | ||
1324 | /* | |
1325 | * Arguments are '\0' separated strings found at the location bprm->p | |
1326 | * points to; chop off the first by relocating brpm->p to right after | |
1327 | * the first '\0' encountered. | |
1328 | */ | |
1329 | int remove_arg_zero(struct linux_binprm *bprm) | |
1330 | { | |
1331 | int ret = 0; | |
1332 | unsigned long offset; | |
1333 | char *kaddr; | |
1334 | struct page *page; | |
1335 | ||
1336 | if (!bprm->argc) | |
1337 | return 0; | |
1338 | ||
1339 | do { | |
1340 | offset = bprm->p & ~PAGE_MASK; | |
1341 | page = get_arg_page(bprm, bprm->p, 0); | |
1342 | if (!page) { | |
1343 | ret = -EFAULT; | |
1344 | goto out; | |
1345 | } | |
1346 | kaddr = kmap_atomic(page); | |
1347 | ||
1348 | for (; offset < PAGE_SIZE && kaddr[offset]; | |
1349 | offset++, bprm->p++) | |
1350 | ; | |
1351 | ||
1352 | kunmap_atomic(kaddr); | |
1353 | put_arg_page(page); | |
1354 | ||
1355 | if (offset == PAGE_SIZE) | |
1356 | free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1); | |
1357 | } while (offset == PAGE_SIZE); | |
1358 | ||
1359 | bprm->p++; | |
1360 | bprm->argc--; | |
1361 | ret = 0; | |
1362 | ||
1363 | out: | |
1364 | return ret; | |
1365 | } | |
1366 | EXPORT_SYMBOL(remove_arg_zero); | |
1367 | ||
1368 | /* | |
1369 | * cycle the list of binary formats handler, until one recognizes the image | |
1370 | */ | |
1371 | int search_binary_handler(struct linux_binprm *bprm) | |
1372 | { | |
1373 | unsigned int depth = bprm->recursion_depth; | |
1374 | int try,retval; | |
1375 | struct linux_binfmt *fmt; | |
1376 | pid_t old_pid, old_vpid; | |
1377 | ||
1378 | /* This allows 4 levels of binfmt rewrites before failing hard. */ | |
1379 | if (depth > 5) | |
1380 | return -ELOOP; | |
1381 | ||
1382 | retval = security_bprm_check(bprm); | |
1383 | if (retval) | |
1384 | return retval; | |
1385 | ||
1386 | retval = audit_bprm(bprm); | |
1387 | if (retval) | |
1388 | return retval; | |
1389 | ||
1390 | /* Need to fetch pid before load_binary changes it */ | |
1391 | old_pid = current->pid; | |
1392 | rcu_read_lock(); | |
1393 | old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent)); | |
1394 | rcu_read_unlock(); | |
1395 | ||
1396 | retval = -ENOENT; | |
1397 | for (try=0; try<2; try++) { | |
1398 | read_lock(&binfmt_lock); | |
1399 | list_for_each_entry(fmt, &formats, lh) { | |
1400 | int (*fn)(struct linux_binprm *) = fmt->load_binary; | |
1401 | if (!fn) | |
1402 | continue; | |
1403 | if (!try_module_get(fmt->module)) | |
1404 | continue; | |
1405 | read_unlock(&binfmt_lock); | |
1406 | bprm->recursion_depth = depth + 1; | |
1407 | retval = fn(bprm); | |
1408 | bprm->recursion_depth = depth; | |
1409 | if (retval >= 0) { | |
1410 | if (depth == 0) { | |
1411 | trace_sched_process_exec(current, old_pid, bprm); | |
1412 | ptrace_event(PTRACE_EVENT_EXEC, old_vpid); | |
1413 | } | |
1414 | put_binfmt(fmt); | |
1415 | allow_write_access(bprm->file); | |
1416 | if (bprm->file) | |
1417 | fput(bprm->file); | |
1418 | bprm->file = NULL; | |
1419 | current->did_exec = 1; | |
1420 | proc_exec_connector(current); | |
1421 | return retval; | |
1422 | } | |
1423 | read_lock(&binfmt_lock); | |
1424 | put_binfmt(fmt); | |
1425 | if (retval != -ENOEXEC || bprm->mm == NULL) | |
1426 | break; | |
1427 | if (!bprm->file) { | |
1428 | read_unlock(&binfmt_lock); | |
1429 | return retval; | |
1430 | } | |
1431 | } | |
1432 | read_unlock(&binfmt_lock); | |
1433 | #ifdef CONFIG_MODULES | |
1434 | if (retval != -ENOEXEC || bprm->mm == NULL) { | |
1435 | break; | |
1436 | } else { | |
1437 | #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e)) | |
1438 | if (printable(bprm->buf[0]) && | |
1439 | printable(bprm->buf[1]) && | |
1440 | printable(bprm->buf[2]) && | |
1441 | printable(bprm->buf[3])) | |
1442 | break; /* -ENOEXEC */ | |
1443 | if (try) | |
1444 | break; /* -ENOEXEC */ | |
1445 | request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2])); | |
1446 | } | |
1447 | #else | |
1448 | break; | |
1449 | #endif | |
1450 | } | |
1451 | return retval; | |
1452 | } | |
1453 | ||
1454 | EXPORT_SYMBOL(search_binary_handler); | |
1455 | ||
1456 | /* | |
1457 | * sys_execve() executes a new program. | |
1458 | */ | |
1459 | static int do_execve_common(const char *filename, | |
1460 | struct user_arg_ptr argv, | |
1461 | struct user_arg_ptr envp) | |
1462 | { | |
1463 | struct linux_binprm *bprm; | |
1464 | struct file *file; | |
1465 | struct files_struct *displaced; | |
1466 | bool clear_in_exec; | |
1467 | int retval; | |
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(¤t_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); | |
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 | { | |
1588 | struct user_arg_ptr argv = { .ptr.native = __argv }; | |
1589 | struct user_arg_ptr envp = { .ptr.native = __envp }; | |
1590 | return do_execve_common(filename, argv, envp); | |
1591 | } | |
1592 | ||
1593 | #ifdef CONFIG_COMPAT | |
1594 | static int compat_do_execve(const char *filename, | |
1595 | const compat_uptr_t __user *__argv, | |
1596 | const compat_uptr_t __user *__envp) | |
1597 | { | |
1598 | struct user_arg_ptr argv = { | |
1599 | .is_compat = true, | |
1600 | .ptr.compat = __argv, | |
1601 | }; | |
1602 | struct user_arg_ptr envp = { | |
1603 | .is_compat = true, | |
1604 | .ptr.compat = __envp, | |
1605 | }; | |
1606 | return do_execve_common(filename, argv, envp); | |
1607 | } | |
1608 | #endif | |
1609 | ||
1610 | void set_binfmt(struct linux_binfmt *new) | |
1611 | { | |
1612 | struct mm_struct *mm = current->mm; | |
1613 | ||
1614 | if (mm->binfmt) | |
1615 | module_put(mm->binfmt->module); | |
1616 | ||
1617 | mm->binfmt = new; | |
1618 | if (new) | |
1619 | __module_get(new->module); | |
1620 | } | |
1621 | ||
1622 | EXPORT_SYMBOL(set_binfmt); | |
1623 | ||
1624 | /* | |
1625 | * set_dumpable converts traditional three-value dumpable to two flags and | |
1626 | * stores them into mm->flags. It modifies lower two bits of mm->flags, but | |
1627 | * these bits are not changed atomically. So get_dumpable can observe the | |
1628 | * intermediate state. To avoid doing unexpected behavior, get get_dumpable | |
1629 | * return either old dumpable or new one by paying attention to the order of | |
1630 | * modifying the bits. | |
1631 | * | |
1632 | * dumpable | mm->flags (binary) | |
1633 | * old new | initial interim final | |
1634 | * ---------+----------------------- | |
1635 | * 0 1 | 00 01 01 | |
1636 | * 0 2 | 00 10(*) 11 | |
1637 | * 1 0 | 01 00 00 | |
1638 | * 1 2 | 01 11 11 | |
1639 | * 2 0 | 11 10(*) 00 | |
1640 | * 2 1 | 11 11 01 | |
1641 | * | |
1642 | * (*) get_dumpable regards interim value of 10 as 11. | |
1643 | */ | |
1644 | void set_dumpable(struct mm_struct *mm, int value) | |
1645 | { | |
1646 | switch (value) { | |
1647 | case SUID_DUMP_DISABLE: | |
1648 | clear_bit(MMF_DUMPABLE, &mm->flags); | |
1649 | smp_wmb(); | |
1650 | clear_bit(MMF_DUMP_SECURELY, &mm->flags); | |
1651 | break; | |
1652 | case SUID_DUMP_USER: | |
1653 | set_bit(MMF_DUMPABLE, &mm->flags); | |
1654 | smp_wmb(); | |
1655 | clear_bit(MMF_DUMP_SECURELY, &mm->flags); | |
1656 | break; | |
1657 | case SUID_DUMP_ROOT: | |
1658 | set_bit(MMF_DUMP_SECURELY, &mm->flags); | |
1659 | smp_wmb(); | |
1660 | set_bit(MMF_DUMPABLE, &mm->flags); | |
1661 | break; | |
1662 | } | |
1663 | } | |
1664 | ||
1665 | int __get_dumpable(unsigned long mm_flags) | |
1666 | { | |
1667 | int ret; | |
1668 | ||
1669 | ret = mm_flags & MMF_DUMPABLE_MASK; | |
1670 | return (ret > SUID_DUMP_USER) ? SUID_DUMP_ROOT : ret; | |
1671 | } | |
1672 | ||
1673 | int get_dumpable(struct mm_struct *mm) | |
1674 | { | |
1675 | return __get_dumpable(mm->flags); | |
1676 | } | |
1677 | ||
1678 | SYSCALL_DEFINE3(execve, | |
1679 | const char __user *, filename, | |
1680 | const char __user *const __user *, argv, | |
1681 | const char __user *const __user *, envp) | |
1682 | { | |
1683 | struct filename *path = getname(filename); | |
1684 | int error = PTR_ERR(path); | |
1685 | if (!IS_ERR(path)) { | |
1686 | error = do_execve(path->name, argv, envp); | |
1687 | putname(path); | |
1688 | } | |
1689 | return error; | |
1690 | } | |
1691 | #ifdef CONFIG_COMPAT | |
1692 | asmlinkage long compat_sys_execve(const char __user * filename, | |
1693 | const compat_uptr_t __user * argv, | |
1694 | const compat_uptr_t __user * envp) | |
1695 | { | |
1696 | struct filename *path = getname(filename); | |
1697 | int error = PTR_ERR(path); | |
1698 | if (!IS_ERR(path)) { | |
1699 | error = compat_do_execve(path->name, argv, envp); | |
1700 | putname(path); | |
1701 | } | |
1702 | return error; | |
1703 | } | |
1704 | #endif |