blob: 7bdea7937ee896179e34b3fe0102f76803fedecb [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Linus Torvalds1da177e2005-04-16 15:20:36 -070025#include <linux/slab.h>
26#include <linux/file.h>
27#include <linux/mman.h>
28#include <linux/a.out.h>
29#include <linux/stat.h>
30#include <linux/fcntl.h>
31#include <linux/smp_lock.h>
32#include <linux/init.h>
33#include <linux/pagemap.h>
34#include <linux/highmem.h>
35#include <linux/spinlock.h>
36#include <linux/key.h>
37#include <linux/personality.h>
38#include <linux/binfmts.h>
39#include <linux/swap.h>
40#include <linux/utsname.h>
Sukadev Bhattiprolu84d73782006-12-08 02:38:01 -080041#include <linux/pid_namespace.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070042#include <linux/module.h>
43#include <linux/namei.h>
44#include <linux/proc_fs.h>
45#include <linux/ptrace.h>
46#include <linux/mount.h>
47#include <linux/security.h>
48#include <linux/syscalls.h>
49#include <linux/rmap.h>
Jay Lan8f0ab512006-09-30 23:28:59 -070050#include <linux/tsacct_kern.h>
Matt Helsley9f460802005-11-07 00:59:16 -080051#include <linux/cn_proc.h>
Al Viro473ae302006-04-26 14:04:08 -040052#include <linux/audit.h>
Davide Libenzifba2afa2007-05-10 22:23:13 -070053#include <linux/signalfd.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070054
55#include <asm/uaccess.h>
56#include <asm/mmu_context.h>
Ollie Wildb6a2fea2007-07-19 01:48:16 -070057#include <asm/tlb.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070058
59#ifdef CONFIG_KMOD
60#include <linux/kmod.h>
61#endif
62
63int core_uses_pid;
Dan Aloni71ce92f2007-05-16 22:11:16 -070064char core_pattern[CORENAME_MAX_SIZE] = "core";
Alan Coxd6e71142005-06-23 00:09:43 -070065int suid_dumpable = 0;
66
67EXPORT_SYMBOL(suid_dumpable);
Linus Torvalds1da177e2005-04-16 15:20:36 -070068/* The maximal length of core_pattern is also specified in sysctl.c */
69
70static struct linux_binfmt *formats;
71static DEFINE_RWLOCK(binfmt_lock);
72
73int register_binfmt(struct linux_binfmt * fmt)
74{
75 struct linux_binfmt ** tmp = &formats;
76
77 if (!fmt)
78 return -EINVAL;
79 if (fmt->next)
80 return -EBUSY;
81 write_lock(&binfmt_lock);
82 while (*tmp) {
83 if (fmt == *tmp) {
84 write_unlock(&binfmt_lock);
85 return -EBUSY;
86 }
87 tmp = &(*tmp)->next;
88 }
89 fmt->next = formats;
90 formats = fmt;
91 write_unlock(&binfmt_lock);
92 return 0;
93}
94
95EXPORT_SYMBOL(register_binfmt);
96
97int unregister_binfmt(struct linux_binfmt * fmt)
98{
99 struct linux_binfmt ** tmp = &formats;
100
101 write_lock(&binfmt_lock);
102 while (*tmp) {
103 if (fmt == *tmp) {
104 *tmp = fmt->next;
kalash nainwal98701d12007-05-08 00:28:31 -0700105 fmt->next = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 write_unlock(&binfmt_lock);
107 return 0;
108 }
109 tmp = &(*tmp)->next;
110 }
111 write_unlock(&binfmt_lock);
112 return -EINVAL;
113}
114
115EXPORT_SYMBOL(unregister_binfmt);
116
117static inline void put_binfmt(struct linux_binfmt * fmt)
118{
119 module_put(fmt->module);
120}
121
122/*
123 * Note that a shared library must be both readable and executable due to
124 * security reasons.
125 *
126 * Also note that we take the address to load from from the file itself.
127 */
128asmlinkage long sys_uselib(const char __user * library)
129{
130 struct file * file;
131 struct nameidata nd;
132 int error;
133
Oleg Drokinb5005312006-03-25 03:07:01 -0800134 error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135 if (error)
136 goto out;
137
Christoph Hellwig492c8b32007-05-23 13:57:53 -0700138 error = -EACCES;
139 if (nd.mnt->mnt_flags & MNT_NOEXEC)
140 goto exit;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 error = -EINVAL;
142 if (!S_ISREG(nd.dentry->d_inode->i_mode))
143 goto exit;
144
Christoph Hellwige4543ed2005-11-08 21:35:04 -0800145 error = vfs_permission(&nd, MAY_READ | MAY_EXEC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 if (error)
147 goto exit;
148
Trond Myklebust834f2a42005-10-18 14:20:16 -0700149 file = nameidata_to_filp(&nd, O_RDONLY);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 error = PTR_ERR(file);
151 if (IS_ERR(file))
152 goto out;
153
154 error = -ENOEXEC;
155 if(file->f_op) {
156 struct linux_binfmt * fmt;
157
158 read_lock(&binfmt_lock);
159 for (fmt = formats ; fmt ; fmt = fmt->next) {
160 if (!fmt->load_shlib)
161 continue;
162 if (!try_module_get(fmt->module))
163 continue;
164 read_unlock(&binfmt_lock);
165 error = fmt->load_shlib(file);
166 read_lock(&binfmt_lock);
167 put_binfmt(fmt);
168 if (error != -ENOEXEC)
169 break;
170 }
171 read_unlock(&binfmt_lock);
172 }
173 fput(file);
174out:
175 return error;
176exit:
Trond Myklebust834f2a42005-10-18 14:20:16 -0700177 release_open_intent(&nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178 path_release(&nd);
179 goto out;
180}
181
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700182#ifdef CONFIG_MMU
183
184static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
185 int write)
186{
187 struct page *page;
188 int ret;
189
190#ifdef CONFIG_STACK_GROWSUP
191 if (write) {
192 ret = expand_stack_downwards(bprm->vma, pos);
193 if (ret < 0)
194 return NULL;
195 }
196#endif
197 ret = get_user_pages(current, bprm->mm, pos,
198 1, write, 1, &page, NULL);
199 if (ret <= 0)
200 return NULL;
201
202 if (write) {
203 struct rlimit *rlim = current->signal->rlim;
204 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
205
206 /*
207 * Limit to 1/4-th the stack size for the argv+env strings.
208 * This ensures that:
209 * - the remaining binfmt code will not run out of stack space,
210 * - the program will have a reasonable amount of stack left
211 * to work from.
212 */
213 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
214 put_page(page);
215 return NULL;
216 }
217 }
218
219 return page;
220}
221
222static void put_arg_page(struct page *page)
223{
224 put_page(page);
225}
226
227static void free_arg_page(struct linux_binprm *bprm, int i)
228{
229}
230
231static void free_arg_pages(struct linux_binprm *bprm)
232{
233}
234
235static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
236 struct page *page)
237{
238 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
239}
240
241static int __bprm_mm_init(struct linux_binprm *bprm)
242{
243 int err = -ENOMEM;
244 struct vm_area_struct *vma = NULL;
245 struct mm_struct *mm = bprm->mm;
246
247 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
248 if (!vma)
249 goto err;
250
251 down_write(&mm->mmap_sem);
252 vma->vm_mm = mm;
253
254 /*
255 * Place the stack at the largest stack address the architecture
256 * supports. Later, we'll move this to an appropriate place. We don't
257 * use STACK_TOP because that can depend on attributes which aren't
258 * configured yet.
259 */
260 vma->vm_end = STACK_TOP_MAX;
261 vma->vm_start = vma->vm_end - PAGE_SIZE;
262
263 vma->vm_flags = VM_STACK_FLAGS;
264 vma->vm_page_prot = protection_map[vma->vm_flags & 0x7];
265 err = insert_vm_struct(mm, vma);
266 if (err) {
267 up_write(&mm->mmap_sem);
268 goto err;
269 }
270
271 mm->stack_vm = mm->total_vm = 1;
272 up_write(&mm->mmap_sem);
273
274 bprm->p = vma->vm_end - sizeof(void *);
275
276 return 0;
277
278err:
279 if (vma) {
280 bprm->vma = NULL;
281 kmem_cache_free(vm_area_cachep, vma);
282 }
283
284 return err;
285}
286
287static bool valid_arg_len(struct linux_binprm *bprm, long len)
288{
289 return len <= MAX_ARG_STRLEN;
290}
291
292#else
293
294static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
295 int write)
296{
297 struct page *page;
298
299 page = bprm->page[pos / PAGE_SIZE];
300 if (!page && write) {
301 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
302 if (!page)
303 return NULL;
304 bprm->page[pos / PAGE_SIZE] = page;
305 }
306
307 return page;
308}
309
310static void put_arg_page(struct page *page)
311{
312}
313
314static void free_arg_page(struct linux_binprm *bprm, int i)
315{
316 if (bprm->page[i]) {
317 __free_page(bprm->page[i]);
318 bprm->page[i] = NULL;
319 }
320}
321
322static void free_arg_pages(struct linux_binprm *bprm)
323{
324 int i;
325
326 for (i = 0; i < MAX_ARG_PAGES; i++)
327 free_arg_page(bprm, i);
328}
329
330static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
331 struct page *page)
332{
333}
334
335static int __bprm_mm_init(struct linux_binprm *bprm)
336{
337 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
338 return 0;
339}
340
341static bool valid_arg_len(struct linux_binprm *bprm, long len)
342{
343 return len <= bprm->p;
344}
345
346#endif /* CONFIG_MMU */
347
348/*
349 * Create a new mm_struct and populate it with a temporary stack
350 * vm_area_struct. We don't have enough context at this point to set the stack
351 * flags, permissions, and offset, so we use temporary values. We'll update
352 * them later in setup_arg_pages().
353 */
354int bprm_mm_init(struct linux_binprm *bprm)
355{
356 int err;
357 struct mm_struct *mm = NULL;
358
359 bprm->mm = mm = mm_alloc();
360 err = -ENOMEM;
361 if (!mm)
362 goto err;
363
364 err = init_new_context(current, mm);
365 if (err)
366 goto err;
367
368 err = __bprm_mm_init(bprm);
369 if (err)
370 goto err;
371
372 return 0;
373
374err:
375 if (mm) {
376 bprm->mm = NULL;
377 mmdrop(mm);
378 }
379
380 return err;
381}
382
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383/*
384 * count() counts the number of strings in array ARGV.
385 */
386static int count(char __user * __user * argv, int max)
387{
388 int i = 0;
389
390 if (argv != NULL) {
391 for (;;) {
392 char __user * p;
393
394 if (get_user(p, argv))
395 return -EFAULT;
396 if (!p)
397 break;
398 argv++;
399 if(++i > max)
400 return -E2BIG;
401 cond_resched();
402 }
403 }
404 return i;
405}
406
407/*
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700408 * 'copy_strings()' copies argument/environment strings from the old
409 * processes's memory to the new process's stack. The call to get_user_pages()
410 * ensures the destination page is created and not swapped out.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411 */
Adrian Bunk75c96f82005-05-05 16:16:09 -0700412static int copy_strings(int argc, char __user * __user * argv,
413 struct linux_binprm *bprm)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414{
415 struct page *kmapped_page = NULL;
416 char *kaddr = NULL;
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700417 unsigned long kpos = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 int ret;
419
420 while (argc-- > 0) {
421 char __user *str;
422 int len;
423 unsigned long pos;
424
425 if (get_user(str, argv+argc) ||
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700426 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 ret = -EFAULT;
428 goto out;
429 }
430
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700431 if (!valid_arg_len(bprm, len)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 ret = -E2BIG;
433 goto out;
434 }
435
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700436 /* We're going to work our way backwords. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700437 pos = bprm->p;
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700438 str += len;
439 bprm->p -= len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440
441 while (len > 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442 int offset, bytes_to_copy;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443
444 offset = pos % PAGE_SIZE;
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700445 if (offset == 0)
446 offset = PAGE_SIZE;
447
448 bytes_to_copy = offset;
449 if (bytes_to_copy > len)
450 bytes_to_copy = len;
451
452 offset -= bytes_to_copy;
453 pos -= bytes_to_copy;
454 str -= bytes_to_copy;
455 len -= bytes_to_copy;
456
457 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
458 struct page *page;
459
460 page = get_arg_page(bprm, pos, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461 if (!page) {
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700462 ret = -E2BIG;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463 goto out;
464 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700466 if (kmapped_page) {
467 flush_kernel_dcache_page(kmapped_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468 kunmap(kmapped_page);
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700469 put_arg_page(kmapped_page);
470 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 kmapped_page = page;
472 kaddr = kmap(kmapped_page);
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700473 kpos = pos & PAGE_MASK;
474 flush_arg_page(bprm, kpos, kmapped_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475 }
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700476 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477 ret = -EFAULT;
478 goto out;
479 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480 }
481 }
482 ret = 0;
483out:
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700484 if (kmapped_page) {
485 flush_kernel_dcache_page(kmapped_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486 kunmap(kmapped_page);
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700487 put_arg_page(kmapped_page);
488 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700489 return ret;
490}
491
492/*
493 * Like copy_strings, but get argv and its values from kernel memory.
494 */
495int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
496{
497 int r;
498 mm_segment_t oldfs = get_fs();
499 set_fs(KERNEL_DS);
500 r = copy_strings(argc, (char __user * __user *)argv, bprm);
501 set_fs(oldfs);
502 return r;
503}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504EXPORT_SYMBOL(copy_strings_kernel);
505
506#ifdef CONFIG_MMU
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700507
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508/*
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700509 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
510 * the binfmt code determines where the new stack should reside, we shift it to
511 * its final location. The process proceeds as follows:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512 *
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700513 * 1) Use shift to calculate the new vma endpoints.
514 * 2) Extend vma to cover both the old and new ranges. This ensures the
515 * arguments passed to subsequent functions are consistent.
516 * 3) Move vma's page tables to the new range.
517 * 4) Free up any cleared pgd range.
518 * 5) Shrink the vma to cover only the new range.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519 */
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700520static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521{
522 struct mm_struct *mm = vma->vm_mm;
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700523 unsigned long old_start = vma->vm_start;
524 unsigned long old_end = vma->vm_end;
525 unsigned long length = old_end - old_start;
526 unsigned long new_start = old_start - shift;
527 unsigned long new_end = old_end - shift;
528 struct mmu_gather *tlb;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700530 BUG_ON(new_start > new_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700532 /*
533 * ensure there are no vmas between where we want to go
534 * and where we are
535 */
536 if (vma != find_vma(mm, new_start))
537 return -EFAULT;
538
539 /*
540 * cover the whole range: [new_start, old_end)
541 */
542 vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
543
544 /*
545 * move the page tables downwards, on failure we rely on
546 * process cleanup to remove whatever mess we made.
547 */
548 if (length != move_page_tables(vma, old_start,
549 vma, new_start, length))
550 return -ENOMEM;
551
552 lru_add_drain();
553 tlb = tlb_gather_mmu(mm, 0);
554 if (new_end > old_start) {
555 /*
556 * when the old and new regions overlap clear from new_end.
557 */
558 free_pgd_range(&tlb, new_end, old_end, new_end,
559 vma->vm_next ? vma->vm_next->vm_start : 0);
560 } else {
561 /*
562 * otherwise, clean from old_start; this is done to not touch
563 * the address space in [new_end, old_start) some architectures
564 * have constraints on va-space that make this illegal (IA64) -
565 * for the others its just a little faster.
566 */
567 free_pgd_range(&tlb, old_start, old_end, new_end,
568 vma->vm_next ? vma->vm_next->vm_start : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569 }
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700570 tlb_finish_mmu(tlb, new_end, old_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700572 /*
573 * shrink the vma to just the new range.
574 */
575 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
576
577 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700578}
579
580#define EXTRA_STACK_VM_PAGES 20 /* random */
581
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700582/*
583 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
584 * the stack is optionally relocated, and some extra space is added.
585 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586int setup_arg_pages(struct linux_binprm *bprm,
587 unsigned long stack_top,
588 int executable_stack)
589{
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700590 unsigned long ret;
591 unsigned long stack_shift;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592 struct mm_struct *mm = current->mm;
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700593 struct vm_area_struct *vma = bprm->vma;
594 struct vm_area_struct *prev = NULL;
595 unsigned long vm_flags;
596 unsigned long stack_base;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700597
598#ifdef CONFIG_STACK_GROWSUP
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599 /* Limit stack size to 1GB */
600 stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
601 if (stack_base > (1 << 30))
602 stack_base = 1 << 30;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700603
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700604 /* Make sure we didn't let the argument array grow too large. */
605 if (vma->vm_end - vma->vm_start > stack_base)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606 return -ENOMEM;
607
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700608 stack_base = PAGE_ALIGN(stack_top - stack_base);
609
610 stack_shift = vma->vm_start - stack_base;
611 mm->arg_start = bprm->p - stack_shift;
612 bprm->p = vma->vm_end - stack_shift;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613#else
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700614 stack_top = arch_align_stack(stack_top);
615 stack_top = PAGE_ALIGN(stack_top);
616 stack_shift = vma->vm_end - stack_top;
617
618 bprm->p -= stack_shift;
619 mm->arg_start = bprm->p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620#endif
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700621
622 if (bprm->loader)
623 bprm->loader -= stack_shift;
624 bprm->exec -= stack_shift;
625
626 down_write(&mm->mmap_sem);
627 vm_flags = vma->vm_flags;
628
629 /*
630 * Adjust stack execute permissions; explicitly enable for
631 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
632 * (arch default) otherwise.
633 */
634 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
635 vm_flags |= VM_EXEC;
636 else if (executable_stack == EXSTACK_DISABLE_X)
637 vm_flags &= ~VM_EXEC;
638 vm_flags |= mm->def_flags;
639
640 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
641 vm_flags);
642 if (ret)
643 goto out_unlock;
644 BUG_ON(prev != vma);
645
646 /* Move stack pages down in memory. */
647 if (stack_shift) {
648 ret = shift_arg_pages(vma, stack_shift);
649 if (ret) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650 up_write(&mm->mmap_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700651 return ret;
652 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653 }
654
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700655#ifdef CONFIG_STACK_GROWSUP
656 stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
657#else
658 stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
659#endif
660 ret = expand_stack(vma, stack_base);
661 if (ret)
662 ret = -EFAULT;
663
664out_unlock:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700665 up_write(&mm->mmap_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666 return 0;
667}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668EXPORT_SYMBOL(setup_arg_pages);
669
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670#endif /* CONFIG_MMU */
671
672struct file *open_exec(const char *name)
673{
674 struct nameidata nd;
675 int err;
676 struct file *file;
677
Oleg Drokinb5005312006-03-25 03:07:01 -0800678 err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679 file = ERR_PTR(err);
680
681 if (!err) {
682 struct inode *inode = nd.dentry->d_inode;
683 file = ERR_PTR(-EACCES);
684 if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
685 S_ISREG(inode->i_mode)) {
Christoph Hellwige4543ed2005-11-08 21:35:04 -0800686 int err = vfs_permission(&nd, MAY_EXEC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687 file = ERR_PTR(err);
688 if (!err) {
Trond Myklebust834f2a42005-10-18 14:20:16 -0700689 file = nameidata_to_filp(&nd, O_RDONLY);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700690 if (!IS_ERR(file)) {
691 err = deny_write_access(file);
692 if (err) {
693 fput(file);
694 file = ERR_PTR(err);
695 }
696 }
697out:
698 return file;
699 }
700 }
Trond Myklebust834f2a42005-10-18 14:20:16 -0700701 release_open_intent(&nd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702 path_release(&nd);
703 }
704 goto out;
705}
706
707EXPORT_SYMBOL(open_exec);
708
709int kernel_read(struct file *file, unsigned long offset,
710 char *addr, unsigned long count)
711{
712 mm_segment_t old_fs;
713 loff_t pos = offset;
714 int result;
715
716 old_fs = get_fs();
717 set_fs(get_ds());
718 /* The cast to a user pointer is valid due to the set_fs() */
719 result = vfs_read(file, (void __user *)addr, count, &pos);
720 set_fs(old_fs);
721 return result;
722}
723
724EXPORT_SYMBOL(kernel_read);
725
726static int exec_mmap(struct mm_struct *mm)
727{
728 struct task_struct *tsk;
729 struct mm_struct * old_mm, *active_mm;
730
731 /* Notify parent that we're no longer interested in the old VM */
732 tsk = current;
733 old_mm = current->mm;
734 mm_release(tsk, old_mm);
735
736 if (old_mm) {
737 /*
738 * Make sure that if there is a core dump in progress
739 * for the old mm, we get out and die instead of going
740 * through with the exec. We must hold mmap_sem around
741 * checking core_waiters and changing tsk->mm. The
742 * core-inducing thread will increment core_waiters for
743 * each thread whose ->mm == old_mm.
744 */
745 down_read(&old_mm->mmap_sem);
746 if (unlikely(old_mm->core_waiters)) {
747 up_read(&old_mm->mmap_sem);
748 return -EINTR;
749 }
750 }
751 task_lock(tsk);
752 active_mm = tsk->active_mm;
753 tsk->mm = mm;
754 tsk->active_mm = mm;
755 activate_mm(active_mm, mm);
756 task_unlock(tsk);
757 arch_pick_mmap_layout(mm);
758 if (old_mm) {
759 up_read(&old_mm->mmap_sem);
Eric Sesterhenn7dddb122006-04-01 01:13:38 +0200760 BUG_ON(active_mm != old_mm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700761 mmput(old_mm);
762 return 0;
763 }
764 mmdrop(active_mm);
765 return 0;
766}
767
768/*
769 * This function makes sure the current process has its own signal table,
770 * so that flush_signal_handlers can later reset the handlers without
771 * disturbing other processes. (Other processes might share the signal
772 * table via the CLONE_SIGHAND option to clone().)
773 */
Arjan van de Ven858119e2006-01-14 13:20:43 -0800774static int de_thread(struct task_struct *tsk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775{
776 struct signal_struct *sig = tsk->signal;
777 struct sighand_struct *newsighand, *oldsighand = tsk->sighand;
778 spinlock_t *lock = &oldsighand->siglock;
Oleg Nesterov329f7db2005-11-07 21:12:43 +0300779 struct task_struct *leader = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700780 int count;
781
782 /*
Davide Libenzifba2afa2007-05-10 22:23:13 -0700783 * Tell all the sighand listeners that this sighand has
784 * been detached. The signalfd_detach() function grabs the
785 * sighand lock, if signal listeners are present on the sighand.
786 */
787 signalfd_detach(tsk);
788
789 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700790 * If we don't share sighandlers, then we aren't sharing anything
791 * and we can just re-use it all.
792 */
793 if (atomic_read(&oldsighand->count) <= 1) {
794 BUG_ON(atomic_read(&sig->count) != 1);
795 exit_itimers(sig);
796 return 0;
797 }
798
799 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
800 if (!newsighand)
801 return -ENOMEM;
802
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700803 if (thread_group_empty(tsk))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804 goto no_thread_group;
805
806 /*
807 * Kill all other threads in the thread group.
808 * We must hold tasklist_lock to call zap_other_threads.
809 */
810 read_lock(&tasklist_lock);
811 spin_lock_irq(lock);
812 if (sig->flags & SIGNAL_GROUP_EXIT) {
813 /*
814 * Another group action in progress, just
815 * return so that the signal is processed.
816 */
817 spin_unlock_irq(lock);
818 read_unlock(&tasklist_lock);
819 kmem_cache_free(sighand_cachep, newsighand);
820 return -EAGAIN;
821 }
Oleg Nesterov14342612006-03-28 16:10:59 -0800822
823 /*
824 * child_reaper ignores SIGKILL, change it now.
825 * Reparenting needs write_lock on tasklist_lock,
826 * so it is safe to do it under read_lock.
827 */
Sukadev Bhattiprolu84d73782006-12-08 02:38:01 -0800828 if (unlikely(tsk->group_leader == child_reaper(tsk)))
829 tsk->nsproxy->pid_ns->child_reaper = tsk;
Oleg Nesterov14342612006-03-28 16:10:59 -0800830
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700831 zap_other_threads(tsk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832 read_unlock(&tasklist_lock);
833
834 /*
835 * Account for the thread group leader hanging around:
836 */
Oleg Nesterov9e4e23b2005-10-30 15:01:37 -0800837 count = 1;
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700838 if (!thread_group_leader(tsk)) {
Oleg Nesterov9e4e23b2005-10-30 15:01:37 -0800839 count = 2;
Roland McGrath53231252005-07-12 13:58:27 -0700840 /*
841 * The SIGALRM timer survives the exec, but needs to point
842 * at us as the new group leader now. We have a race with
843 * a timer firing now getting the old leader, so we need to
844 * synchronize with any firing (by calling del_timer_sync)
845 * before we can safely let the old group leader die.
846 */
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700847 sig->tsk = tsk;
Oleg Nesterov932aeaf2005-10-30 15:02:17 -0800848 spin_unlock_irq(lock);
Thomas Gleixner2ff678b2006-01-09 20:52:34 -0800849 if (hrtimer_cancel(&sig->real_timer))
850 hrtimer_restart(&sig->real_timer);
Oleg Nesterov932aeaf2005-10-30 15:02:17 -0800851 spin_lock_irq(lock);
Roland McGrath53231252005-07-12 13:58:27 -0700852 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700853 while (atomic_read(&sig->count) > count) {
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700854 sig->group_exit_task = tsk;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855 sig->notify_count = count;
856 __set_current_state(TASK_UNINTERRUPTIBLE);
857 spin_unlock_irq(lock);
858 schedule();
859 spin_lock_irq(lock);
860 }
861 sig->group_exit_task = NULL;
862 sig->notify_count = 0;
863 spin_unlock_irq(lock);
864
865 /*
866 * At this point all other threads have exited, all we have to
867 * do is to wait for the thread group leader to become inactive,
868 * and to assume its PID:
869 */
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700870 if (!thread_group_leader(tsk)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700871 /*
872 * Wait for the thread group leader to be a zombie.
873 * It should already be zombie at this point, most
874 * of the time.
875 */
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700876 leader = tsk->group_leader;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700877 while (leader->exit_state != EXIT_ZOMBIE)
878 yield();
879
Roland McGrathf5e90282006-04-10 22:54:16 -0700880 /*
881 * The only record we have of the real-time age of a
882 * process, regardless of execs it's done, is start_time.
883 * All the past CPU time is accumulated in signal_struct
884 * from sister threads now dead. But in this non-leader
885 * exec, nothing survives from the original leader thread,
886 * whose birth marks the true age of this process now.
887 * When we take on its identity by switching to its PID, we
888 * also take its birthdate (always earlier than our own).
889 */
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700890 tsk->start_time = leader->start_time;
Roland McGrathf5e90282006-04-10 22:54:16 -0700891
Linus Torvalds1da177e2005-04-16 15:20:36 -0700892 write_lock_irq(&tasklist_lock);
893
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700894 BUG_ON(leader->tgid != tsk->tgid);
895 BUG_ON(tsk->pid == tsk->tgid);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700896 /*
897 * An exec() starts a new thread group with the
898 * TGID of the previous thread group. Rehash the
899 * two threads with a switched PID, and release
900 * the former thread group leader:
901 */
Eric W. Biedermand73d6522006-03-28 16:11:03 -0800902
903 /* Become a process group leader with the old leader's pid.
Eric W. Biedermanc18258c2006-09-27 01:51:06 -0700904 * The old leader becomes a thread of the this thread group.
905 * Note: The old leader also uses this pid until release_task
Eric W. Biedermand73d6522006-03-28 16:11:03 -0800906 * is called. Odd but simple and correct.
907 */
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700908 detach_pid(tsk, PIDTYPE_PID);
909 tsk->pid = leader->pid;
Sukadev Bhattiprolue713d0d2007-05-10 22:22:58 -0700910 attach_pid(tsk, PIDTYPE_PID, find_pid(tsk->pid));
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700911 transfer_pid(leader, tsk, PIDTYPE_PGID);
912 transfer_pid(leader, tsk, PIDTYPE_SID);
913 list_replace_rcu(&leader->tasks, &tsk->tasks);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700914
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700915 tsk->group_leader = tsk;
916 leader->group_leader = tsk;
Eric W. Biedermande12a782006-04-10 17:16:49 -0600917
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700918 tsk->exit_signal = SIGCHLD;
Oleg Nesterov962b5642005-11-23 13:37:43 -0800919
920 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
921 leader->exit_state = EXIT_DEAD;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700922
923 write_unlock_irq(&tasklist_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700924 }
925
926 /*
Alexander Nybergfb085cf2005-09-14 18:54:06 +0200927 * There may be one thread left which is just exiting,
928 * but it's safe to stop telling the group to kill themselves.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700929 */
930 sig->flags = 0;
931
932no_thread_group:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700933 exit_itimers(sig);
Oleg Nesterov329f7db2005-11-07 21:12:43 +0300934 if (leader)
935 release_task(leader);
936
937 BUG_ON(atomic_read(&sig->count) != 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700938
939 if (atomic_read(&oldsighand->count) == 1) {
940 /*
941 * Now that we nuked the rest of the thread group,
942 * it turns out we are not sharing sighand any more either.
943 * So we can just keep it.
944 */
945 kmem_cache_free(sighand_cachep, newsighand);
946 } else {
947 /*
948 * Move our state over to newsighand and switch it in.
949 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700950 atomic_set(&newsighand->count, 1);
951 memcpy(newsighand->action, oldsighand->action,
952 sizeof(newsighand->action));
953
954 write_lock_irq(&tasklist_lock);
955 spin_lock(&oldsighand->siglock);
Dave Jones513627d2006-08-27 01:23:57 -0700956 spin_lock_nested(&newsighand->siglock, SINGLE_DEPTH_NESTING);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700957
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700958 rcu_assign_pointer(tsk->sighand, newsighand);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700959 recalc_sigpending();
960
961 spin_unlock(&newsighand->siglock);
962 spin_unlock(&oldsighand->siglock);
963 write_unlock_irq(&tasklist_lock);
964
Davide Libenzifba2afa2007-05-10 22:23:13 -0700965 __cleanup_sighand(oldsighand);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700966 }
967
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700968 BUG_ON(!thread_group_leader(tsk));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700969 return 0;
970}
971
972/*
973 * These functions flushes out all traces of the currently running executable
974 * so that a new one can be started
975 */
976
Arjan van de Ven858119e2006-01-14 13:20:43 -0800977static void flush_old_files(struct files_struct * files)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700978{
979 long j = -1;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700980 struct fdtable *fdt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700981
982 spin_lock(&files->file_lock);
983 for (;;) {
984 unsigned long set, i;
985
986 j++;
987 i = j * __NFDBITS;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700988 fdt = files_fdtable(files);
Vadim Lobanovbbea9f62006-12-10 02:21:12 -0800989 if (i >= fdt->max_fds)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700990 break;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700991 set = fdt->close_on_exec->fds_bits[j];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700992 if (!set)
993 continue;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700994 fdt->close_on_exec->fds_bits[j] = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700995 spin_unlock(&files->file_lock);
996 for ( ; set ; i++,set >>= 1) {
997 if (set & 1) {
998 sys_close(i);
999 }
1000 }
1001 spin_lock(&files->file_lock);
1002
1003 }
1004 spin_unlock(&files->file_lock);
1005}
1006
1007void get_task_comm(char *buf, struct task_struct *tsk)
1008{
1009 /* buf must be at least sizeof(tsk->comm) in size */
1010 task_lock(tsk);
1011 strncpy(buf, tsk->comm, sizeof(tsk->comm));
1012 task_unlock(tsk);
1013}
1014
1015void set_task_comm(struct task_struct *tsk, char *buf)
1016{
1017 task_lock(tsk);
1018 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1019 task_unlock(tsk);
1020}
1021
1022int flush_old_exec(struct linux_binprm * bprm)
1023{
1024 char * name;
1025 int i, ch, retval;
1026 struct files_struct *files;
1027 char tcomm[sizeof(current->comm)];
1028
1029 /*
1030 * Make sure we have a private signal table and that
1031 * we are unassociated from the previous thread group.
1032 */
1033 retval = de_thread(current);
1034 if (retval)
1035 goto out;
1036
1037 /*
1038 * Make sure we have private file handles. Ask the
1039 * fork helper to do the work for us and the exit
1040 * helper to do the cleanup of the old one.
1041 */
1042 files = current->files; /* refcounted so safe to hold */
1043 retval = unshare_files();
1044 if (retval)
1045 goto out;
1046 /*
1047 * Release all of the old mmap stuff
1048 */
1049 retval = exec_mmap(bprm->mm);
1050 if (retval)
1051 goto mmap_failed;
1052
1053 bprm->mm = NULL; /* We're using it now */
1054
1055 /* This is the point of no return */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001056 put_files_struct(files);
1057
1058 current->sas_ss_sp = current->sas_ss_size = 0;
1059
1060 if (current->euid == current->uid && current->egid == current->gid)
Kawai, Hidehiro6c5d5232007-07-19 01:48:27 -07001061 set_dumpable(current->mm, 1);
Alan Coxd6e71142005-06-23 00:09:43 -07001062 else
Kawai, Hidehiro6c5d5232007-07-19 01:48:27 -07001063 set_dumpable(current->mm, suid_dumpable);
Alan Coxd6e71142005-06-23 00:09:43 -07001064
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065 name = bprm->filename;
Paolo 'Blaisorblade' Giarrusso36772092005-05-05 16:16:12 -07001066
1067 /* Copies the binary name from after last slash */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001068 for (i=0; (ch = *(name++)) != '\0';) {
1069 if (ch == '/')
Paolo 'Blaisorblade' Giarrusso36772092005-05-05 16:16:12 -07001070 i = 0; /* overwrite what we wrote */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001071 else
1072 if (i < (sizeof(tcomm) - 1))
1073 tcomm[i++] = ch;
1074 }
1075 tcomm[i] = '\0';
1076 set_task_comm(current, tcomm);
1077
1078 current->flags &= ~PF_RANDOMIZE;
1079 flush_thread();
1080
Benjamin Herrenschmidt0551fbd2006-02-28 16:59:19 -08001081 /* Set the new mm task size. We have to do that late because it may
1082 * depend on TIF_32BIT which is only updated in flush_thread() on
1083 * some architectures like powerpc
1084 */
1085 current->mm->task_size = TASK_SIZE;
1086
Linus Torvalds1da177e2005-04-16 15:20:36 -07001087 if (bprm->e_uid != current->euid || bprm->e_gid != current->egid ||
Christoph Hellwig8c744fb2005-11-08 21:35:04 -08001088 file_permission(bprm->file, MAY_READ) ||
Linus Torvalds1da177e2005-04-16 15:20:36 -07001089 (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
1090 suid_keys(current);
Kawai, Hidehiro6c5d5232007-07-19 01:48:27 -07001091 set_dumpable(current->mm, suid_dumpable);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001092 }
1093
1094 /* An exec changes our domain. We are no longer part of the thread
1095 group */
1096
1097 current->self_exec_id++;
1098
1099 flush_signal_handlers(current, 0);
1100 flush_old_files(current->files);
1101
1102 return 0;
1103
1104mmap_failed:
Kirill Korotaev3b9b8ab2006-09-29 02:00:05 -07001105 reset_files_struct(current, files);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001106out:
1107 return retval;
1108}
1109
1110EXPORT_SYMBOL(flush_old_exec);
1111
1112/*
1113 * Fill the binprm structure from the inode.
1114 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1115 */
1116int prepare_binprm(struct linux_binprm *bprm)
1117{
1118 int mode;
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001119 struct inode * inode = bprm->file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001120 int retval;
1121
1122 mode = inode->i_mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001123 if (bprm->file->f_op == NULL)
1124 return -EACCES;
1125
1126 bprm->e_uid = current->euid;
1127 bprm->e_gid = current->egid;
1128
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001129 if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001130 /* Set-uid? */
1131 if (mode & S_ISUID) {
1132 current->personality &= ~PER_CLEAR_ON_SETID;
1133 bprm->e_uid = inode->i_uid;
1134 }
1135
1136 /* Set-gid? */
1137 /*
1138 * If setgid is set but no group execute bit then this
1139 * is a candidate for mandatory locking, not a setgid
1140 * executable.
1141 */
1142 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1143 current->personality &= ~PER_CLEAR_ON_SETID;
1144 bprm->e_gid = inode->i_gid;
1145 }
1146 }
1147
1148 /* fill in binprm security blob */
1149 retval = security_bprm_set(bprm);
1150 if (retval)
1151 return retval;
1152
1153 memset(bprm->buf,0,BINPRM_BUF_SIZE);
1154 return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
1155}
1156
1157EXPORT_SYMBOL(prepare_binprm);
1158
Arjan van de Ven858119e2006-01-14 13:20:43 -08001159static int unsafe_exec(struct task_struct *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001160{
1161 int unsafe = 0;
1162 if (p->ptrace & PT_PTRACED) {
1163 if (p->ptrace & PT_PTRACE_CAP)
1164 unsafe |= LSM_UNSAFE_PTRACE_CAP;
1165 else
1166 unsafe |= LSM_UNSAFE_PTRACE;
1167 }
1168 if (atomic_read(&p->fs->count) > 1 ||
1169 atomic_read(&p->files->count) > 1 ||
1170 atomic_read(&p->sighand->count) > 1)
1171 unsafe |= LSM_UNSAFE_SHARE;
1172
1173 return unsafe;
1174}
1175
1176void compute_creds(struct linux_binprm *bprm)
1177{
1178 int unsafe;
1179
1180 if (bprm->e_uid != current->uid)
1181 suid_keys(current);
1182 exec_keys(current);
1183
1184 task_lock(current);
1185 unsafe = unsafe_exec(current);
1186 security_bprm_apply_creds(bprm, unsafe);
1187 task_unlock(current);
1188 security_bprm_post_apply_creds(bprm);
1189}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001190EXPORT_SYMBOL(compute_creds);
1191
Nick Piggin4fc75ff2007-05-08 00:25:16 -07001192/*
1193 * Arguments are '\0' separated strings found at the location bprm->p
1194 * points to; chop off the first by relocating brpm->p to right after
1195 * the first '\0' encountered.
1196 */
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001197int remove_arg_zero(struct linux_binprm *bprm)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001198{
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001199 int ret = 0;
1200 unsigned long offset;
1201 char *kaddr;
1202 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001203
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001204 if (!bprm->argc)
1205 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001207 do {
1208 offset = bprm->p & ~PAGE_MASK;
1209 page = get_arg_page(bprm, bprm->p, 0);
1210 if (!page) {
1211 ret = -EFAULT;
1212 goto out;
1213 }
1214 kaddr = kmap_atomic(page, KM_USER0);
Nick Piggin4fc75ff2007-05-08 00:25:16 -07001215
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001216 for (; offset < PAGE_SIZE && kaddr[offset];
1217 offset++, bprm->p++)
1218 ;
Nick Piggin4fc75ff2007-05-08 00:25:16 -07001219
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001220 kunmap_atomic(kaddr, KM_USER0);
1221 put_arg_page(page);
Nick Piggin4fc75ff2007-05-08 00:25:16 -07001222
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001223 if (offset == PAGE_SIZE)
1224 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1225 } while (offset == PAGE_SIZE);
Nick Piggin4fc75ff2007-05-08 00:25:16 -07001226
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001227 bprm->p++;
1228 bprm->argc--;
1229 ret = 0;
Nick Piggin4fc75ff2007-05-08 00:25:16 -07001230
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001231out:
1232 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001233}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001234EXPORT_SYMBOL(remove_arg_zero);
1235
1236/*
1237 * cycle the list of binary formats handler, until one recognizes the image
1238 */
1239int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1240{
1241 int try,retval;
1242 struct linux_binfmt *fmt;
1243#ifdef __alpha__
1244 /* handle /sbin/loader.. */
1245 {
1246 struct exec * eh = (struct exec *) bprm->buf;
1247
1248 if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1249 (eh->fh.f_flags & 0x3000) == 0x3000)
1250 {
1251 struct file * file;
1252 unsigned long loader;
1253
1254 allow_write_access(bprm->file);
1255 fput(bprm->file);
1256 bprm->file = NULL;
1257
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001258 loader = bprm->vma->vm_end - sizeof(void *);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001259
1260 file = open_exec("/sbin/loader");
1261 retval = PTR_ERR(file);
1262 if (IS_ERR(file))
1263 return retval;
1264
1265 /* Remember if the application is TASO. */
1266 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1267
1268 bprm->file = file;
1269 bprm->loader = loader;
1270 retval = prepare_binprm(bprm);
1271 if (retval<0)
1272 return retval;
1273 /* should call search_binary_handler recursively here,
1274 but it does not matter */
1275 }
1276 }
1277#endif
1278 retval = security_bprm_check(bprm);
1279 if (retval)
1280 return retval;
1281
1282 /* kernel module loader fixup */
1283 /* so we don't try to load run modprobe in kernel space. */
1284 set_fs(USER_DS);
Al Viro473ae302006-04-26 14:04:08 -04001285
1286 retval = audit_bprm(bprm);
1287 if (retval)
1288 return retval;
1289
Linus Torvalds1da177e2005-04-16 15:20:36 -07001290 retval = -ENOENT;
1291 for (try=0; try<2; try++) {
1292 read_lock(&binfmt_lock);
1293 for (fmt = formats ; fmt ; fmt = fmt->next) {
1294 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1295 if (!fn)
1296 continue;
1297 if (!try_module_get(fmt->module))
1298 continue;
1299 read_unlock(&binfmt_lock);
1300 retval = fn(bprm, regs);
1301 if (retval >= 0) {
1302 put_binfmt(fmt);
1303 allow_write_access(bprm->file);
1304 if (bprm->file)
1305 fput(bprm->file);
1306 bprm->file = NULL;
1307 current->did_exec = 1;
Matt Helsley9f460802005-11-07 00:59:16 -08001308 proc_exec_connector(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001309 return retval;
1310 }
1311 read_lock(&binfmt_lock);
1312 put_binfmt(fmt);
1313 if (retval != -ENOEXEC || bprm->mm == NULL)
1314 break;
1315 if (!bprm->file) {
1316 read_unlock(&binfmt_lock);
1317 return retval;
1318 }
1319 }
1320 read_unlock(&binfmt_lock);
1321 if (retval != -ENOEXEC || bprm->mm == NULL) {
1322 break;
1323#ifdef CONFIG_KMOD
1324 }else{
1325#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1326 if (printable(bprm->buf[0]) &&
1327 printable(bprm->buf[1]) &&
1328 printable(bprm->buf[2]) &&
1329 printable(bprm->buf[3]))
1330 break; /* -ENOEXEC */
1331 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1332#endif
1333 }
1334 }
1335 return retval;
1336}
1337
1338EXPORT_SYMBOL(search_binary_handler);
1339
1340/*
1341 * sys_execve() executes a new program.
1342 */
1343int do_execve(char * filename,
1344 char __user *__user *argv,
1345 char __user *__user *envp,
1346 struct pt_regs * regs)
1347{
1348 struct linux_binprm *bprm;
1349 struct file *file;
Peter Zijlstrabdf4c482007-07-19 01:48:15 -07001350 unsigned long env_p;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001351 int retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001352
1353 retval = -ENOMEM;
Oliver Neukum11b0b5a2006-03-25 03:08:13 -08001354 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001355 if (!bprm)
1356 goto out_ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001357
1358 file = open_exec(filename);
1359 retval = PTR_ERR(file);
1360 if (IS_ERR(file))
1361 goto out_kfree;
1362
1363 sched_exec();
1364
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365 bprm->file = file;
1366 bprm->filename = filename;
1367 bprm->interp = filename;
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001368
1369 retval = bprm_mm_init(bprm);
1370 if (retval)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001371 goto out_file;
1372
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001373 bprm->argc = count(argv, MAX_ARG_STRINGS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001374 if ((retval = bprm->argc) < 0)
1375 goto out_mm;
1376
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001377 bprm->envc = count(envp, MAX_ARG_STRINGS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001378 if ((retval = bprm->envc) < 0)
1379 goto out_mm;
1380
1381 retval = security_bprm_alloc(bprm);
1382 if (retval)
1383 goto out;
1384
1385 retval = prepare_binprm(bprm);
1386 if (retval < 0)
1387 goto out;
1388
1389 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1390 if (retval < 0)
1391 goto out;
1392
1393 bprm->exec = bprm->p;
1394 retval = copy_strings(bprm->envc, envp, bprm);
1395 if (retval < 0)
1396 goto out;
1397
Peter Zijlstrabdf4c482007-07-19 01:48:15 -07001398 env_p = bprm->p;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399 retval = copy_strings(bprm->argc, argv, bprm);
1400 if (retval < 0)
1401 goto out;
Peter Zijlstrabdf4c482007-07-19 01:48:15 -07001402 bprm->argv_len = env_p - bprm->p;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403
1404 retval = search_binary_handler(bprm,regs);
1405 if (retval >= 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001406 /* execve success */
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001407 free_arg_pages(bprm);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001408 security_bprm_free(bprm);
1409 acct_update_integrals(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001410 kfree(bprm);
1411 return retval;
1412 }
1413
1414out:
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001415 free_arg_pages(bprm);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001416 if (bprm->security)
1417 security_bprm_free(bprm);
1418
1419out_mm:
1420 if (bprm->mm)
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001421 mmput (bprm->mm);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001422
1423out_file:
1424 if (bprm->file) {
1425 allow_write_access(bprm->file);
1426 fput(bprm->file);
1427 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428out_kfree:
1429 kfree(bprm);
1430
1431out_ret:
1432 return retval;
1433}
1434
1435int set_binfmt(struct linux_binfmt *new)
1436{
1437 struct linux_binfmt *old = current->binfmt;
1438
1439 if (new) {
1440 if (!try_module_get(new->module))
1441 return -1;
1442 }
1443 current->binfmt = new;
1444 if (old)
1445 module_put(old->module);
1446 return 0;
1447}
1448
1449EXPORT_SYMBOL(set_binfmt);
1450
Linus Torvalds1da177e2005-04-16 15:20:36 -07001451/* format_corename will inspect the pattern parameter, and output a
1452 * name into corename, which must have space for at least
1453 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1454 */
Alan Coxc4bbafd2007-04-16 22:53:13 -07001455static int format_corename(char *corename, const char *pattern, long signr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001456{
1457 const char *pat_ptr = pattern;
1458 char *out_ptr = corename;
1459 char *const out_end = corename + CORENAME_MAX_SIZE;
1460 int rc;
1461 int pid_in_pattern = 0;
Alan Coxc4bbafd2007-04-16 22:53:13 -07001462 int ispipe = 0;
1463
1464 if (*pattern == '|')
1465 ispipe = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466
1467 /* Repeat as long as we have more pattern to process and more output
1468 space */
1469 while (*pat_ptr) {
1470 if (*pat_ptr != '%') {
1471 if (out_ptr == out_end)
1472 goto out;
1473 *out_ptr++ = *pat_ptr++;
1474 } else {
1475 switch (*++pat_ptr) {
1476 case 0:
1477 goto out;
1478 /* Double percent, output one percent */
1479 case '%':
1480 if (out_ptr == out_end)
1481 goto out;
1482 *out_ptr++ = '%';
1483 break;
1484 /* pid */
1485 case 'p':
1486 pid_in_pattern = 1;
1487 rc = snprintf(out_ptr, out_end - out_ptr,
1488 "%d", current->tgid);
1489 if (rc > out_end - out_ptr)
1490 goto out;
1491 out_ptr += rc;
1492 break;
1493 /* uid */
1494 case 'u':
1495 rc = snprintf(out_ptr, out_end - out_ptr,
1496 "%d", current->uid);
1497 if (rc > out_end - out_ptr)
1498 goto out;
1499 out_ptr += rc;
1500 break;
1501 /* gid */
1502 case 'g':
1503 rc = snprintf(out_ptr, out_end - out_ptr,
1504 "%d", current->gid);
1505 if (rc > out_end - out_ptr)
1506 goto out;
1507 out_ptr += rc;
1508 break;
1509 /* signal that caused the coredump */
1510 case 's':
1511 rc = snprintf(out_ptr, out_end - out_ptr,
1512 "%ld", signr);
1513 if (rc > out_end - out_ptr)
1514 goto out;
1515 out_ptr += rc;
1516 break;
1517 /* UNIX time of coredump */
1518 case 't': {
1519 struct timeval tv;
1520 do_gettimeofday(&tv);
1521 rc = snprintf(out_ptr, out_end - out_ptr,
1522 "%lu", tv.tv_sec);
1523 if (rc > out_end - out_ptr)
1524 goto out;
1525 out_ptr += rc;
1526 break;
1527 }
1528 /* hostname */
1529 case 'h':
1530 down_read(&uts_sem);
1531 rc = snprintf(out_ptr, out_end - out_ptr,
Serge E. Hallyne9ff3992006-10-02 02:18:11 -07001532 "%s", utsname()->nodename);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001533 up_read(&uts_sem);
1534 if (rc > out_end - out_ptr)
1535 goto out;
1536 out_ptr += rc;
1537 break;
1538 /* executable */
1539 case 'e':
1540 rc = snprintf(out_ptr, out_end - out_ptr,
1541 "%s", current->comm);
1542 if (rc > out_end - out_ptr)
1543 goto out;
1544 out_ptr += rc;
1545 break;
1546 default:
1547 break;
1548 }
1549 ++pat_ptr;
1550 }
1551 }
1552 /* Backward compatibility with core_uses_pid:
1553 *
1554 * If core_pattern does not include a %p (as is the default)
1555 * and core_uses_pid is set, then .%pid will be appended to
Alan Coxc4bbafd2007-04-16 22:53:13 -07001556 * the filename. Do not do this for piped commands. */
1557 if (!ispipe && !pid_in_pattern
Linus Torvalds1da177e2005-04-16 15:20:36 -07001558 && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1559 rc = snprintf(out_ptr, out_end - out_ptr,
1560 ".%d", current->tgid);
1561 if (rc > out_end - out_ptr)
1562 goto out;
1563 out_ptr += rc;
1564 }
Alan Coxc4bbafd2007-04-16 22:53:13 -07001565out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001566 *out_ptr = 0;
Alan Coxc4bbafd2007-04-16 22:53:13 -07001567 return ispipe;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001568}
1569
Oleg Nesterovd5f70c02006-06-26 00:26:07 -07001570static void zap_process(struct task_struct *start)
Oleg Nesterovaceecc042006-06-26 00:26:05 -07001571{
1572 struct task_struct *t;
Oleg Nesterov281de332006-06-26 00:26:06 -07001573
Oleg Nesterovd5f70c02006-06-26 00:26:07 -07001574 start->signal->flags = SIGNAL_GROUP_EXIT;
1575 start->signal->group_stop_count = 0;
Oleg Nesterovaceecc042006-06-26 00:26:05 -07001576
1577 t = start;
1578 do {
1579 if (t != current && t->mm) {
1580 t->mm->core_waiters++;
Oleg Nesterov281de332006-06-26 00:26:06 -07001581 sigaddset(&t->pending.signal, SIGKILL);
1582 signal_wake_up(t, 1);
Oleg Nesterovaceecc042006-06-26 00:26:05 -07001583 }
1584 } while ((t = next_thread(t)) != start);
1585}
1586
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001587static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1588 int exit_code)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001589{
1590 struct task_struct *g, *p;
Oleg Nesterov5debfa62006-06-26 00:26:09 -07001591 unsigned long flags;
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001592 int err = -EAGAIN;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001593
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001594 spin_lock_irq(&tsk->sighand->siglock);
1595 if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001596 tsk->signal->group_exit_code = exit_code;
Oleg Nesterov5debfa62006-06-26 00:26:09 -07001597 zap_process(tsk);
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001598 err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001599 }
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001600 spin_unlock_irq(&tsk->sighand->siglock);
1601 if (err)
1602 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001603
Oleg Nesterov5debfa62006-06-26 00:26:09 -07001604 if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)
1605 goto done;
1606
Oleg Nesterov7b1c6152006-06-26 00:26:08 -07001607 rcu_read_lock();
Oleg Nesterovaceecc042006-06-26 00:26:05 -07001608 for_each_process(g) {
Oleg Nesterov5debfa62006-06-26 00:26:09 -07001609 if (g == tsk->group_leader)
1610 continue;
1611
Oleg Nesterovaceecc042006-06-26 00:26:05 -07001612 p = g;
1613 do {
1614 if (p->mm) {
Oleg Nesterov5debfa62006-06-26 00:26:09 -07001615 if (p->mm == mm) {
1616 /*
1617 * p->sighand can't disappear, but
1618 * may be changed by de_thread()
1619 */
1620 lock_task_sighand(p, &flags);
Oleg Nesterovd5f70c02006-06-26 00:26:07 -07001621 zap_process(p);
Oleg Nesterov5debfa62006-06-26 00:26:09 -07001622 unlock_task_sighand(p, &flags);
1623 }
Oleg Nesterovaceecc042006-06-26 00:26:05 -07001624 break;
1625 }
1626 } while ((p = next_thread(p)) != g);
1627 }
Oleg Nesterov7b1c6152006-06-26 00:26:08 -07001628 rcu_read_unlock();
Oleg Nesterov5debfa62006-06-26 00:26:09 -07001629done:
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001630 return mm->core_waiters;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001631}
1632
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001633static int coredump_wait(int exit_code)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001634{
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001635 struct task_struct *tsk = current;
1636 struct mm_struct *mm = tsk->mm;
1637 struct completion startup_done;
1638 struct completion *vfork_done;
Oleg Nesterov2384f552005-10-30 15:02:47 -08001639 int core_waiters;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001640
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001641 init_completion(&mm->core_done);
1642 init_completion(&startup_done);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001643 mm->core_startup_done = &startup_done;
1644
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001645 core_waiters = zap_threads(tsk, mm, exit_code);
Oleg Nesterov2384f552005-10-30 15:02:47 -08001646 up_write(&mm->mmap_sem);
1647
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001648 if (unlikely(core_waiters < 0))
1649 goto fail;
1650
1651 /*
1652 * Make sure nobody is waiting for us to release the VM,
1653 * otherwise we can deadlock when we wait on each other
1654 */
1655 vfork_done = tsk->vfork_done;
1656 if (vfork_done) {
1657 tsk->vfork_done = NULL;
1658 complete(vfork_done);
1659 }
1660
Oleg Nesterov2384f552005-10-30 15:02:47 -08001661 if (core_waiters)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001662 wait_for_completion(&startup_done);
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001663fail:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001664 BUG_ON(mm->core_waiters);
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001665 return core_waiters;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001666}
1667
Kawai, Hidehiro6c5d5232007-07-19 01:48:27 -07001668/*
1669 * set_dumpable converts traditional three-value dumpable to two flags and
1670 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1671 * these bits are not changed atomically. So get_dumpable can observe the
1672 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1673 * return either old dumpable or new one by paying attention to the order of
1674 * modifying the bits.
1675 *
1676 * dumpable | mm->flags (binary)
1677 * old new | initial interim final
1678 * ---------+-----------------------
1679 * 0 1 | 00 01 01
1680 * 0 2 | 00 10(*) 11
1681 * 1 0 | 01 00 00
1682 * 1 2 | 01 11 11
1683 * 2 0 | 11 10(*) 00
1684 * 2 1 | 11 11 01
1685 *
1686 * (*) get_dumpable regards interim value of 10 as 11.
1687 */
1688void set_dumpable(struct mm_struct *mm, int value)
1689{
1690 switch (value) {
1691 case 0:
1692 clear_bit(MMF_DUMPABLE, &mm->flags);
1693 smp_wmb();
1694 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1695 break;
1696 case 1:
1697 set_bit(MMF_DUMPABLE, &mm->flags);
1698 smp_wmb();
1699 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1700 break;
1701 case 2:
1702 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1703 smp_wmb();
1704 set_bit(MMF_DUMPABLE, &mm->flags);
1705 break;
1706 }
1707}
1708EXPORT_SYMBOL_GPL(set_dumpable);
1709
1710int get_dumpable(struct mm_struct *mm)
1711{
1712 int ret;
1713
1714 ret = mm->flags & 0x3;
1715 return (ret >= 2) ? 2 : ret;
1716}
1717
Linus Torvalds1da177e2005-04-16 15:20:36 -07001718int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1719{
1720 char corename[CORENAME_MAX_SIZE + 1];
1721 struct mm_struct *mm = current->mm;
1722 struct linux_binfmt * binfmt;
1723 struct inode * inode;
1724 struct file * file;
1725 int retval = 0;
Alan Coxd6e71142005-06-23 00:09:43 -07001726 int fsuid = current->fsuid;
1727 int flag = 0;
Andi Kleend025c9d2006-09-30 23:29:28 -07001728 int ispipe = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001729
Steve Grubb0a4ff8c2007-04-19 10:28:21 -04001730 audit_core_dumps(signr);
1731
Linus Torvalds1da177e2005-04-16 15:20:36 -07001732 binfmt = current->binfmt;
1733 if (!binfmt || !binfmt->core_dump)
1734 goto fail;
1735 down_write(&mm->mmap_sem);
Kawai, Hidehiro6c5d5232007-07-19 01:48:27 -07001736 if (!get_dumpable(mm)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001737 up_write(&mm->mmap_sem);
1738 goto fail;
1739 }
Alan Coxd6e71142005-06-23 00:09:43 -07001740
1741 /*
1742 * We cannot trust fsuid as being the "true" uid of the
1743 * process nor do we know its entire history. We only know it
1744 * was tainted so we dump it as root in mode 2.
1745 */
Kawai, Hidehiro6c5d5232007-07-19 01:48:27 -07001746 if (get_dumpable(mm) == 2) { /* Setuid core dump mode */
Alan Coxd6e71142005-06-23 00:09:43 -07001747 flag = O_EXCL; /* Stop rewrite attacks */
1748 current->fsuid = 0; /* Dump root private */
1749 }
Kawai, Hidehiro6c5d5232007-07-19 01:48:27 -07001750 set_dumpable(mm, 0);
Oleg Nesterov1291cf42005-10-30 15:02:54 -08001751
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001752 retval = coredump_wait(exit_code);
1753 if (retval < 0)
Oleg Nesterov1291cf42005-10-30 15:02:54 -08001754 goto fail;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001755
1756 /*
1757 * Clear any false indication of pending signals that might
1758 * be seen by the filesystem code called to write the core file.
1759 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001760 clear_thread_flag(TIF_SIGPENDING);
1761
1762 if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
1763 goto fail_unlock;
1764
1765 /*
1766 * lock_kernel() because format_corename() is controlled by sysctl, which
1767 * uses lock_kernel()
1768 */
1769 lock_kernel();
Alan Coxc4bbafd2007-04-16 22:53:13 -07001770 ispipe = format_corename(corename, core_pattern, signr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001771 unlock_kernel();
Alan Coxc4bbafd2007-04-16 22:53:13 -07001772 if (ispipe) {
Andi Kleend025c9d2006-09-30 23:29:28 -07001773 /* SIGPIPE can happen, but it's just never processed */
1774 if(call_usermodehelper_pipe(corename+1, NULL, NULL, &file)) {
1775 printk(KERN_INFO "Core dump to %s pipe failed\n",
1776 corename);
1777 goto fail_unlock;
1778 }
Andi Kleend025c9d2006-09-30 23:29:28 -07001779 } else
1780 file = filp_open(corename,
Alexey Dobriyan6d4df672006-12-06 20:40:39 -08001781 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1782 0600);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001783 if (IS_ERR(file))
1784 goto fail_unlock;
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001785 inode = file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001786 if (inode->i_nlink > 1)
1787 goto close_fail; /* multiple links - don't dump */
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001788 if (!ispipe && d_unhashed(file->f_path.dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001789 goto close_fail;
1790
Andi Kleend025c9d2006-09-30 23:29:28 -07001791 /* AK: actually i see no reason to not allow this for named pipes etc.,
1792 but keep the previous behaviour for now. */
1793 if (!ispipe && !S_ISREG(inode->i_mode))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001794 goto close_fail;
1795 if (!file->f_op)
1796 goto close_fail;
1797 if (!file->f_op->write)
1798 goto close_fail;
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001799 if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001800 goto close_fail;
1801
1802 retval = binfmt->core_dump(signr, regs, file);
1803
1804 if (retval)
1805 current->signal->group_exit_code |= 0x80;
1806close_fail:
1807 filp_close(file, NULL);
1808fail_unlock:
Alan Coxd6e71142005-06-23 00:09:43 -07001809 current->fsuid = fsuid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001810 complete_all(&mm->core_done);
1811fail:
1812 return retval;
1813}