blob: 9696bbf0f0b1c1b1bd4578fdbfac331fa62ffc48 [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>
Al Viro9f3acc32008-04-24 07:44:08 -040027#include <linux/fdtable.h>
Hugh Dickinsba92a432008-07-25 01:45:43 -070028#include <linux/mm.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#include <linux/stat.h>
30#include <linux/fcntl.h>
31#include <linux/smp_lock.h>
Hugh Dickinsba92a432008-07-25 01:45:43 -070032#include <linux/swap.h>
Neil Horman74aadce2007-10-16 23:26:35 -070033#include <linux/string.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070034#include <linux/init.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035#include <linux/highmem.h>
36#include <linux/spinlock.h>
37#include <linux/key.h>
38#include <linux/personality.h>
39#include <linux/binfmts.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070040#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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070045#include <linux/mount.h>
46#include <linux/security.h>
47#include <linux/syscalls.h>
Jay Lan8f0ab512006-09-30 23:28:59 -070048#include <linux/tsacct_kern.h>
Matt Helsley9f460802005-11-07 00:59:16 -080049#include <linux/cn_proc.h>
Al Viro473ae302006-04-26 14:04:08 -040050#include <linux/audit.h>
Roland McGrath6341c392008-07-25 19:45:44 -070051#include <linux/tracehook.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070052
53#include <asm/uaccess.h>
54#include <asm/mmu_context.h>
Ollie Wildb6a2fea2007-07-19 01:48:16 -070055#include <asm/tlb.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070056
57#ifdef CONFIG_KMOD
58#include <linux/kmod.h>
59#endif
60
David Woodhouse702773b2008-06-16 12:11:54 +010061#ifdef __alpha__
62/* for /sbin/loader handling in search_binary_handler() */
63#include <linux/a.out.h>
64#endif
65
Linus Torvalds1da177e2005-04-16 15:20:36 -070066int core_uses_pid;
Dan Aloni71ce92f2007-05-16 22:11:16 -070067char core_pattern[CORENAME_MAX_SIZE] = "core";
Alan Coxd6e71142005-06-23 00:09:43 -070068int suid_dumpable = 0;
69
Linus Torvalds1da177e2005-04-16 15:20:36 -070070/* The maximal length of core_pattern is also specified in sysctl.c */
71
Alexey Dobriyane4dc1b12007-10-16 23:26:03 -070072static LIST_HEAD(formats);
Linus Torvalds1da177e2005-04-16 15:20:36 -070073static DEFINE_RWLOCK(binfmt_lock);
74
75int register_binfmt(struct linux_binfmt * fmt)
76{
Linus Torvalds1da177e2005-04-16 15:20:36 -070077 if (!fmt)
78 return -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -070079 write_lock(&binfmt_lock);
Alexey Dobriyane4dc1b12007-10-16 23:26:03 -070080 list_add(&fmt->lh, &formats);
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 write_unlock(&binfmt_lock);
82 return 0;
83}
84
85EXPORT_SYMBOL(register_binfmt);
86
Alexey Dobriyanf6b450d2007-10-16 23:26:04 -070087void unregister_binfmt(struct linux_binfmt * fmt)
Linus Torvalds1da177e2005-04-16 15:20:36 -070088{
Linus Torvalds1da177e2005-04-16 15:20:36 -070089 write_lock(&binfmt_lock);
Alexey Dobriyane4dc1b12007-10-16 23:26:03 -070090 list_del(&fmt->lh);
Linus Torvalds1da177e2005-04-16 15:20:36 -070091 write_unlock(&binfmt_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070092}
93
94EXPORT_SYMBOL(unregister_binfmt);
95
96static inline void put_binfmt(struct linux_binfmt * fmt)
97{
98 module_put(fmt->module);
99}
100
101/*
102 * Note that a shared library must be both readable and executable due to
103 * security reasons.
104 *
105 * Also note that we take the address to load from from the file itself.
106 */
107asmlinkage long sys_uselib(const char __user * library)
108{
Al Viro964bd182008-07-26 03:33:14 -0400109 struct file *file;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110 struct nameidata nd;
Al Viro964bd182008-07-26 03:33:14 -0400111 char *tmp = getname(library);
112 int error = PTR_ERR(tmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113
Al Viro964bd182008-07-26 03:33:14 -0400114 if (!IS_ERR(tmp)) {
115 error = path_lookup_open(AT_FDCWD, tmp,
116 LOOKUP_FOLLOW, &nd,
117 FMODE_READ|FMODE_EXEC);
118 putname(tmp);
119 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 if (error)
121 goto out;
122
123 error = -EINVAL;
Jan Blunck4ac91372008-02-14 19:34:32 -0800124 if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125 goto exit;
126
Al Viro30524472008-07-22 00:02:33 -0400127 error = -EACCES;
128 if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
129 goto exit;
130
Al Virob77b0642008-07-17 09:37:02 -0400131 error = vfs_permission(&nd, MAY_READ | MAY_EXEC | MAY_OPEN);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132 if (error)
133 goto exit;
134
Andi Kleenabe8be32008-02-08 04:20:23 -0800135 file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136 error = PTR_ERR(file);
137 if (IS_ERR(file))
138 goto out;
139
140 error = -ENOEXEC;
141 if(file->f_op) {
142 struct linux_binfmt * fmt;
143
144 read_lock(&binfmt_lock);
Alexey Dobriyane4dc1b12007-10-16 23:26:03 -0700145 list_for_each_entry(fmt, &formats, lh) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 if (!fmt->load_shlib)
147 continue;
148 if (!try_module_get(fmt->module))
149 continue;
150 read_unlock(&binfmt_lock);
151 error = fmt->load_shlib(file);
152 read_lock(&binfmt_lock);
153 put_binfmt(fmt);
154 if (error != -ENOEXEC)
155 break;
156 }
157 read_unlock(&binfmt_lock);
158 }
159 fput(file);
160out:
161 return error;
162exit:
Trond Myklebust834f2a42005-10-18 14:20:16 -0700163 release_open_intent(&nd);
Jan Blunck1d957f92008-02-14 19:34:35 -0800164 path_put(&nd.path);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165 goto out;
166}
167
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700168#ifdef CONFIG_MMU
169
170static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
171 int write)
172{
173 struct page *page;
174 int ret;
175
176#ifdef CONFIG_STACK_GROWSUP
177 if (write) {
178 ret = expand_stack_downwards(bprm->vma, pos);
179 if (ret < 0)
180 return NULL;
181 }
182#endif
183 ret = get_user_pages(current, bprm->mm, pos,
184 1, write, 1, &page, NULL);
185 if (ret <= 0)
186 return NULL;
187
188 if (write) {
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700189 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
Linus Torvaldsa64e7152008-03-03 10:12:14 -0800190 struct rlimit *rlim;
191
192 /*
193 * We've historically supported up to 32 pages (ARG_MAX)
194 * of argument strings even with small stacks
195 */
196 if (size <= ARG_MAX)
197 return page;
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700198
199 /*
200 * Limit to 1/4-th the stack size for the argv+env strings.
201 * This ensures that:
202 * - the remaining binfmt code will not run out of stack space,
203 * - the program will have a reasonable amount of stack left
204 * to work from.
205 */
Linus Torvaldsa64e7152008-03-03 10:12:14 -0800206 rlim = current->signal->rlim;
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700207 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
208 put_page(page);
209 return NULL;
210 }
211 }
212
213 return page;
214}
215
216static void put_arg_page(struct page *page)
217{
218 put_page(page);
219}
220
221static void free_arg_page(struct linux_binprm *bprm, int i)
222{
223}
224
225static void free_arg_pages(struct linux_binprm *bprm)
226{
227}
228
229static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
230 struct page *page)
231{
232 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
233}
234
235static int __bprm_mm_init(struct linux_binprm *bprm)
236{
237 int err = -ENOMEM;
238 struct vm_area_struct *vma = NULL;
239 struct mm_struct *mm = bprm->mm;
240
241 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
242 if (!vma)
243 goto err;
244
245 down_write(&mm->mmap_sem);
246 vma->vm_mm = mm;
247
248 /*
249 * Place the stack at the largest stack address the architecture
250 * supports. Later, we'll move this to an appropriate place. We don't
251 * use STACK_TOP because that can depend on attributes which aren't
252 * configured yet.
253 */
254 vma->vm_end = STACK_TOP_MAX;
255 vma->vm_start = vma->vm_end - PAGE_SIZE;
256
257 vma->vm_flags = VM_STACK_FLAGS;
Coly Li3ed75eb2007-10-18 23:39:15 -0700258 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700259 err = insert_vm_struct(mm, vma);
260 if (err) {
261 up_write(&mm->mmap_sem);
262 goto err;
263 }
264
265 mm->stack_vm = mm->total_vm = 1;
266 up_write(&mm->mmap_sem);
267
268 bprm->p = vma->vm_end - sizeof(void *);
269
270 return 0;
271
272err:
273 if (vma) {
274 bprm->vma = NULL;
275 kmem_cache_free(vm_area_cachep, vma);
276 }
277
278 return err;
279}
280
281static bool valid_arg_len(struct linux_binprm *bprm, long len)
282{
283 return len <= MAX_ARG_STRLEN;
284}
285
286#else
287
288static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
289 int write)
290{
291 struct page *page;
292
293 page = bprm->page[pos / PAGE_SIZE];
294 if (!page && write) {
295 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
296 if (!page)
297 return NULL;
298 bprm->page[pos / PAGE_SIZE] = page;
299 }
300
301 return page;
302}
303
304static void put_arg_page(struct page *page)
305{
306}
307
308static void free_arg_page(struct linux_binprm *bprm, int i)
309{
310 if (bprm->page[i]) {
311 __free_page(bprm->page[i]);
312 bprm->page[i] = NULL;
313 }
314}
315
316static void free_arg_pages(struct linux_binprm *bprm)
317{
318 int i;
319
320 for (i = 0; i < MAX_ARG_PAGES; i++)
321 free_arg_page(bprm, i);
322}
323
324static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
325 struct page *page)
326{
327}
328
329static int __bprm_mm_init(struct linux_binprm *bprm)
330{
331 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
332 return 0;
333}
334
335static bool valid_arg_len(struct linux_binprm *bprm, long len)
336{
337 return len <= bprm->p;
338}
339
340#endif /* CONFIG_MMU */
341
342/*
343 * Create a new mm_struct and populate it with a temporary stack
344 * vm_area_struct. We don't have enough context at this point to set the stack
345 * flags, permissions, and offset, so we use temporary values. We'll update
346 * them later in setup_arg_pages().
347 */
348int bprm_mm_init(struct linux_binprm *bprm)
349{
350 int err;
351 struct mm_struct *mm = NULL;
352
353 bprm->mm = mm = mm_alloc();
354 err = -ENOMEM;
355 if (!mm)
356 goto err;
357
358 err = init_new_context(current, mm);
359 if (err)
360 goto err;
361
362 err = __bprm_mm_init(bprm);
363 if (err)
364 goto err;
365
366 return 0;
367
368err:
369 if (mm) {
370 bprm->mm = NULL;
371 mmdrop(mm);
372 }
373
374 return err;
375}
376
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377/*
378 * count() counts the number of strings in array ARGV.
379 */
380static int count(char __user * __user * argv, int max)
381{
382 int i = 0;
383
384 if (argv != NULL) {
385 for (;;) {
386 char __user * p;
387
388 if (get_user(p, argv))
389 return -EFAULT;
390 if (!p)
391 break;
392 argv++;
393 if(++i > max)
394 return -E2BIG;
395 cond_resched();
396 }
397 }
398 return i;
399}
400
401/*
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700402 * 'copy_strings()' copies argument/environment strings from the old
403 * processes's memory to the new process's stack. The call to get_user_pages()
404 * ensures the destination page is created and not swapped out.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405 */
Adrian Bunk75c96f82005-05-05 16:16:09 -0700406static int copy_strings(int argc, char __user * __user * argv,
407 struct linux_binprm *bprm)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408{
409 struct page *kmapped_page = NULL;
410 char *kaddr = NULL;
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700411 unsigned long kpos = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 int ret;
413
414 while (argc-- > 0) {
415 char __user *str;
416 int len;
417 unsigned long pos;
418
419 if (get_user(str, argv+argc) ||
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700420 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421 ret = -EFAULT;
422 goto out;
423 }
424
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700425 if (!valid_arg_len(bprm, len)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426 ret = -E2BIG;
427 goto out;
428 }
429
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700430 /* We're going to work our way backwords. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 pos = bprm->p;
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700432 str += len;
433 bprm->p -= len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434
435 while (len > 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436 int offset, bytes_to_copy;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700437
438 offset = pos % PAGE_SIZE;
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700439 if (offset == 0)
440 offset = PAGE_SIZE;
441
442 bytes_to_copy = offset;
443 if (bytes_to_copy > len)
444 bytes_to_copy = len;
445
446 offset -= bytes_to_copy;
447 pos -= bytes_to_copy;
448 str -= bytes_to_copy;
449 len -= bytes_to_copy;
450
451 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
452 struct page *page;
453
454 page = get_arg_page(bprm, pos, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455 if (!page) {
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700456 ret = -E2BIG;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457 goto out;
458 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700460 if (kmapped_page) {
461 flush_kernel_dcache_page(kmapped_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462 kunmap(kmapped_page);
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700463 put_arg_page(kmapped_page);
464 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465 kmapped_page = page;
466 kaddr = kmap(kmapped_page);
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700467 kpos = pos & PAGE_MASK;
468 flush_arg_page(bprm, kpos, kmapped_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469 }
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700470 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 ret = -EFAULT;
472 goto out;
473 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474 }
475 }
476 ret = 0;
477out:
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700478 if (kmapped_page) {
479 flush_kernel_dcache_page(kmapped_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480 kunmap(kmapped_page);
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700481 put_arg_page(kmapped_page);
482 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483 return ret;
484}
485
486/*
487 * Like copy_strings, but get argv and its values from kernel memory.
488 */
489int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
490{
491 int r;
492 mm_segment_t oldfs = get_fs();
493 set_fs(KERNEL_DS);
494 r = copy_strings(argc, (char __user * __user *)argv, bprm);
495 set_fs(oldfs);
496 return r;
497}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498EXPORT_SYMBOL(copy_strings_kernel);
499
500#ifdef CONFIG_MMU
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700501
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502/*
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700503 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
504 * the binfmt code determines where the new stack should reside, we shift it to
505 * its final location. The process proceeds as follows:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506 *
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700507 * 1) Use shift to calculate the new vma endpoints.
508 * 2) Extend vma to cover both the old and new ranges. This ensures the
509 * arguments passed to subsequent functions are consistent.
510 * 3) Move vma's page tables to the new range.
511 * 4) Free up any cleared pgd range.
512 * 5) Shrink the vma to cover only the new range.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513 */
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700514static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515{
516 struct mm_struct *mm = vma->vm_mm;
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700517 unsigned long old_start = vma->vm_start;
518 unsigned long old_end = vma->vm_end;
519 unsigned long length = old_end - old_start;
520 unsigned long new_start = old_start - shift;
521 unsigned long new_end = old_end - shift;
522 struct mmu_gather *tlb;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700524 BUG_ON(new_start > new_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700526 /*
527 * ensure there are no vmas between where we want to go
528 * and where we are
529 */
530 if (vma != find_vma(mm, new_start))
531 return -EFAULT;
532
533 /*
534 * cover the whole range: [new_start, old_end)
535 */
536 vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
537
538 /*
539 * move the page tables downwards, on failure we rely on
540 * process cleanup to remove whatever mess we made.
541 */
542 if (length != move_page_tables(vma, old_start,
543 vma, new_start, length))
544 return -ENOMEM;
545
546 lru_add_drain();
547 tlb = tlb_gather_mmu(mm, 0);
548 if (new_end > old_start) {
549 /*
550 * when the old and new regions overlap clear from new_end.
551 */
Jan Beulich42b77722008-07-23 21:27:10 -0700552 free_pgd_range(tlb, new_end, old_end, new_end,
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700553 vma->vm_next ? vma->vm_next->vm_start : 0);
554 } else {
555 /*
556 * otherwise, clean from old_start; this is done to not touch
557 * the address space in [new_end, old_start) some architectures
558 * have constraints on va-space that make this illegal (IA64) -
559 * for the others its just a little faster.
560 */
Jan Beulich42b77722008-07-23 21:27:10 -0700561 free_pgd_range(tlb, old_start, old_end, new_end,
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700562 vma->vm_next ? vma->vm_next->vm_start : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563 }
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700564 tlb_finish_mmu(tlb, new_end, old_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700566 /*
567 * shrink the vma to just the new range.
568 */
569 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
570
571 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572}
573
574#define EXTRA_STACK_VM_PAGES 20 /* random */
575
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700576/*
577 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
578 * the stack is optionally relocated, and some extra space is added.
579 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580int setup_arg_pages(struct linux_binprm *bprm,
581 unsigned long stack_top,
582 int executable_stack)
583{
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700584 unsigned long ret;
585 unsigned long stack_shift;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586 struct mm_struct *mm = current->mm;
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700587 struct vm_area_struct *vma = bprm->vma;
588 struct vm_area_struct *prev = NULL;
589 unsigned long vm_flags;
590 unsigned long stack_base;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591
592#ifdef CONFIG_STACK_GROWSUP
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593 /* Limit stack size to 1GB */
594 stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
595 if (stack_base > (1 << 30))
596 stack_base = 1 << 30;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700597
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700598 /* Make sure we didn't let the argument array grow too large. */
599 if (vma->vm_end - vma->vm_start > stack_base)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700600 return -ENOMEM;
601
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700602 stack_base = PAGE_ALIGN(stack_top - stack_base);
603
604 stack_shift = vma->vm_start - stack_base;
605 mm->arg_start = bprm->p - stack_shift;
606 bprm->p = vma->vm_end - stack_shift;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607#else
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700608 stack_top = arch_align_stack(stack_top);
609 stack_top = PAGE_ALIGN(stack_top);
610 stack_shift = vma->vm_end - stack_top;
611
612 bprm->p -= stack_shift;
613 mm->arg_start = bprm->p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700614#endif
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700615
616 if (bprm->loader)
617 bprm->loader -= stack_shift;
618 bprm->exec -= stack_shift;
619
620 down_write(&mm->mmap_sem);
Hugh Dickins96a8e132008-07-10 21:19:20 +0100621 vm_flags = VM_STACK_FLAGS;
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700622
623 /*
624 * Adjust stack execute permissions; explicitly enable for
625 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
626 * (arch default) otherwise.
627 */
628 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
629 vm_flags |= VM_EXEC;
630 else if (executable_stack == EXSTACK_DISABLE_X)
631 vm_flags &= ~VM_EXEC;
632 vm_flags |= mm->def_flags;
633
634 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
635 vm_flags);
636 if (ret)
637 goto out_unlock;
638 BUG_ON(prev != vma);
639
640 /* Move stack pages down in memory. */
641 if (stack_shift) {
642 ret = shift_arg_pages(vma, stack_shift);
643 if (ret) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644 up_write(&mm->mmap_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645 return ret;
646 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647 }
648
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700649#ifdef CONFIG_STACK_GROWSUP
650 stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
651#else
652 stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
653#endif
654 ret = expand_stack(vma, stack_base);
655 if (ret)
656 ret = -EFAULT;
657
658out_unlock:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659 up_write(&mm->mmap_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700660 return 0;
661}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700662EXPORT_SYMBOL(setup_arg_pages);
663
Linus Torvalds1da177e2005-04-16 15:20:36 -0700664#endif /* CONFIG_MMU */
665
666struct file *open_exec(const char *name)
667{
668 struct nameidata nd;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700669 struct file *file;
Christoph Hellwige56b6a52008-05-19 07:53:34 +0200670 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671
Christoph Hellwige56b6a52008-05-19 07:53:34 +0200672 err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd,
673 FMODE_READ|FMODE_EXEC);
674 if (err)
675 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676
Christoph Hellwige56b6a52008-05-19 07:53:34 +0200677 err = -EACCES;
678 if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
679 goto out_path_put;
680
Al Viro30524472008-07-22 00:02:33 -0400681 if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
682 goto out_path_put;
683
Christoph Hellwige56b6a52008-05-19 07:53:34 +0200684 err = vfs_permission(&nd, MAY_EXEC | MAY_OPEN);
685 if (err)
686 goto out_path_put;
687
688 file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
689 if (IS_ERR(file))
690 return file;
691
692 err = deny_write_access(file);
693 if (err) {
694 fput(file);
695 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700696 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697
Christoph Hellwige56b6a52008-05-19 07:53:34 +0200698 return file;
699
700 out_path_put:
701 release_open_intent(&nd);
702 path_put(&nd.path);
703 out:
704 return ERR_PTR(err);
705}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700706EXPORT_SYMBOL(open_exec);
707
708int kernel_read(struct file *file, unsigned long offset,
709 char *addr, unsigned long count)
710{
711 mm_segment_t old_fs;
712 loff_t pos = offset;
713 int result;
714
715 old_fs = get_fs();
716 set_fs(get_ds());
717 /* The cast to a user pointer is valid due to the set_fs() */
718 result = vfs_read(file, (void __user *)addr, count, &pos);
719 set_fs(old_fs);
720 return result;
721}
722
723EXPORT_SYMBOL(kernel_read);
724
725static int exec_mmap(struct mm_struct *mm)
726{
727 struct task_struct *tsk;
728 struct mm_struct * old_mm, *active_mm;
729
730 /* Notify parent that we're no longer interested in the old VM */
731 tsk = current;
732 old_mm = current->mm;
733 mm_release(tsk, old_mm);
734
735 if (old_mm) {
736 /*
737 * Make sure that if there is a core dump in progress
738 * for the old mm, we get out and die instead of going
739 * through with the exec. We must hold mmap_sem around
Oleg Nesterov999d9fc2008-07-25 01:47:41 -0700740 * checking core_state and changing tsk->mm.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741 */
742 down_read(&old_mm->mmap_sem);
Oleg Nesterov999d9fc2008-07-25 01:47:41 -0700743 if (unlikely(old_mm->core_state)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700744 up_read(&old_mm->mmap_sem);
745 return -EINTR;
746 }
747 }
748 task_lock(tsk);
749 active_mm = tsk->active_mm;
750 tsk->mm = mm;
751 tsk->active_mm = mm;
752 activate_mm(active_mm, mm);
753 task_unlock(tsk);
KOSAKI Motohiro4cd1a8f2008-05-12 14:02:31 -0700754 mm_update_next_owner(old_mm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755 arch_pick_mmap_layout(mm);
756 if (old_mm) {
757 up_read(&old_mm->mmap_sem);
Eric Sesterhenn7dddb122006-04-01 01:13:38 +0200758 BUG_ON(active_mm != old_mm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700759 mmput(old_mm);
760 return 0;
761 }
762 mmdrop(active_mm);
763 return 0;
764}
765
766/*
767 * This function makes sure the current process has its own signal table,
768 * so that flush_signal_handlers can later reset the handlers without
769 * disturbing other processes. (Other processes might share the signal
770 * table via the CLONE_SIGHAND option to clone().)
771 */
Arjan van de Ven858119e2006-01-14 13:20:43 -0800772static int de_thread(struct task_struct *tsk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700773{
774 struct signal_struct *sig = tsk->signal;
Oleg Nesterovb2c903b2007-10-16 23:27:22 -0700775 struct sighand_struct *oldsighand = tsk->sighand;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 spinlock_t *lock = &oldsighand->siglock;
Oleg Nesterov329f7db2005-11-07 21:12:43 +0300777 struct task_struct *leader = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700778 int count;
779
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700780 if (thread_group_empty(tsk))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781 goto no_thread_group;
782
783 /*
784 * Kill all other threads in the thread group.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700785 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786 spin_lock_irq(lock);
Oleg Nesteroved5d2ca2008-02-04 22:27:24 -0800787 if (signal_group_exit(sig)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700788 /*
789 * Another group action in progress, just
790 * return so that the signal is processed.
791 */
792 spin_unlock_irq(lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700793 return -EAGAIN;
794 }
Oleg Nesteroved5d2ca2008-02-04 22:27:24 -0800795 sig->group_exit_task = tsk;
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700796 zap_other_threads(tsk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700797
Oleg Nesterovfea9d172008-02-08 04:19:19 -0800798 /* Account for the thread group leader hanging around: */
799 count = thread_group_leader(tsk) ? 1 : 2;
Oleg Nesterov6db840f2007-10-16 23:27:23 -0700800 sig->notify_count = count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801 while (atomic_read(&sig->count) > count) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700802 __set_current_state(TASK_UNINTERRUPTIBLE);
803 spin_unlock_irq(lock);
804 schedule();
805 spin_lock_irq(lock);
806 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700807 spin_unlock_irq(lock);
808
809 /*
810 * At this point all other threads have exited, all we have to
811 * do is to wait for the thread group leader to become inactive,
812 * and to assume its PID:
813 */
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700814 if (!thread_group_leader(tsk)) {
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700815 leader = tsk->group_leader;
Oleg Nesterov6db840f2007-10-16 23:27:23 -0700816
Oleg Nesterov2800d8d2008-04-30 00:53:12 -0700817 sig->notify_count = -1; /* for exit_notify() */
Oleg Nesterov6db840f2007-10-16 23:27:23 -0700818 for (;;) {
819 write_lock_irq(&tasklist_lock);
820 if (likely(leader->exit_state))
821 break;
822 __set_current_state(TASK_UNINTERRUPTIBLE);
823 write_unlock_irq(&tasklist_lock);
824 schedule();
825 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700826
Oleg Nesterov7a5e8732008-04-30 00:53:04 -0700827 if (unlikely(task_child_reaper(tsk) == leader))
828 task_active_pid_ns(tsk)->child_reaper = tsk;
Roland McGrathf5e90282006-04-10 22:54:16 -0700829 /*
830 * The only record we have of the real-time age of a
831 * process, regardless of execs it's done, is start_time.
832 * All the past CPU time is accumulated in signal_struct
833 * from sister threads now dead. But in this non-leader
834 * exec, nothing survives from the original leader thread,
835 * whose birth marks the true age of this process now.
836 * When we take on its identity by switching to its PID, we
837 * also take its birthdate (always earlier than our own).
838 */
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700839 tsk->start_time = leader->start_time;
Roland McGrathf5e90282006-04-10 22:54:16 -0700840
Pavel Emelyanovbac0abd2007-10-18 23:40:18 -0700841 BUG_ON(!same_thread_group(leader, tsk));
842 BUG_ON(has_group_leader_pid(tsk));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843 /*
844 * An exec() starts a new thread group with the
845 * TGID of the previous thread group. Rehash the
846 * two threads with a switched PID, and release
847 * the former thread group leader:
848 */
Eric W. Biedermand73d6522006-03-28 16:11:03 -0800849
850 /* Become a process group leader with the old leader's pid.
Eric W. Biedermanc18258c2006-09-27 01:51:06 -0700851 * The old leader becomes a thread of the this thread group.
852 * Note: The old leader also uses this pid until release_task
Eric W. Biedermand73d6522006-03-28 16:11:03 -0800853 * is called. Odd but simple and correct.
854 */
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700855 detach_pid(tsk, PIDTYPE_PID);
856 tsk->pid = leader->pid;
Sukadev Bhattiprolu3743ca02007-10-18 23:39:51 -0700857 attach_pid(tsk, PIDTYPE_PID, task_pid(leader));
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700858 transfer_pid(leader, tsk, PIDTYPE_PGID);
859 transfer_pid(leader, tsk, PIDTYPE_SID);
860 list_replace_rcu(&leader->tasks, &tsk->tasks);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700861
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700862 tsk->group_leader = tsk;
863 leader->group_leader = tsk;
Eric W. Biedermande12a782006-04-10 17:16:49 -0600864
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700865 tsk->exit_signal = SIGCHLD;
Oleg Nesterov962b5642005-11-23 13:37:43 -0800866
867 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
868 leader->exit_state = EXIT_DEAD;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700869
870 write_unlock_irq(&tasklist_lock);
Oleg Nesteroved5d2ca2008-02-04 22:27:24 -0800871 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700872
Oleg Nesterov6db840f2007-10-16 23:27:23 -0700873 sig->group_exit_task = NULL;
874 sig->notify_count = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875
876no_thread_group:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700877 exit_itimers(sig);
Oleg Nesterovcbaffba2008-05-26 20:55:42 +0400878 flush_itimer_signals();
Oleg Nesterov329f7db2005-11-07 21:12:43 +0300879 if (leader)
880 release_task(leader);
881
Oleg Nesterovb2c903b2007-10-16 23:27:22 -0700882 if (atomic_read(&oldsighand->count) != 1) {
883 struct sighand_struct *newsighand;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700884 /*
Oleg Nesterovb2c903b2007-10-16 23:27:22 -0700885 * This ->sighand is shared with the CLONE_SIGHAND
886 * but not CLONE_THREAD task, switch to the new one.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700887 */
Oleg Nesterovb2c903b2007-10-16 23:27:22 -0700888 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
889 if (!newsighand)
890 return -ENOMEM;
891
Linus Torvalds1da177e2005-04-16 15:20:36 -0700892 atomic_set(&newsighand->count, 1);
893 memcpy(newsighand->action, oldsighand->action,
894 sizeof(newsighand->action));
895
896 write_lock_irq(&tasklist_lock);
897 spin_lock(&oldsighand->siglock);
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700898 rcu_assign_pointer(tsk->sighand, newsighand);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700899 spin_unlock(&oldsighand->siglock);
900 write_unlock_irq(&tasklist_lock);
901
Davide Libenzifba2afa2007-05-10 22:23:13 -0700902 __cleanup_sighand(oldsighand);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903 }
904
Eric W. Biedermanaafe6c22006-09-27 01:51:13 -0700905 BUG_ON(!thread_group_leader(tsk));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700906 return 0;
907}
Oleg Nesterov0840a902007-10-16 23:27:22 -0700908
Linus Torvalds1da177e2005-04-16 15:20:36 -0700909/*
910 * These functions flushes out all traces of the currently running executable
911 * so that a new one can be started
912 */
Arjan van de Ven858119e2006-01-14 13:20:43 -0800913static void flush_old_files(struct files_struct * files)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700914{
915 long j = -1;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700916 struct fdtable *fdt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917
918 spin_lock(&files->file_lock);
919 for (;;) {
920 unsigned long set, i;
921
922 j++;
923 i = j * __NFDBITS;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700924 fdt = files_fdtable(files);
Vadim Lobanovbbea9f62006-12-10 02:21:12 -0800925 if (i >= fdt->max_fds)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700926 break;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700927 set = fdt->close_on_exec->fds_bits[j];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700928 if (!set)
929 continue;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700930 fdt->close_on_exec->fds_bits[j] = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700931 spin_unlock(&files->file_lock);
932 for ( ; set ; i++,set >>= 1) {
933 if (set & 1) {
934 sys_close(i);
935 }
936 }
937 spin_lock(&files->file_lock);
938
939 }
940 spin_unlock(&files->file_lock);
941}
942
Andrew Morton59714d62008-02-04 22:27:21 -0800943char *get_task_comm(char *buf, struct task_struct *tsk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944{
945 /* buf must be at least sizeof(tsk->comm) in size */
946 task_lock(tsk);
947 strncpy(buf, tsk->comm, sizeof(tsk->comm));
948 task_unlock(tsk);
Andrew Morton59714d62008-02-04 22:27:21 -0800949 return buf;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700950}
951
952void set_task_comm(struct task_struct *tsk, char *buf)
953{
954 task_lock(tsk);
955 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
956 task_unlock(tsk);
957}
958
959int flush_old_exec(struct linux_binprm * bprm)
960{
961 char * name;
962 int i, ch, retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700963 char tcomm[sizeof(current->comm)];
964
965 /*
966 * Make sure we have a private signal table and that
967 * we are unassociated from the previous thread group.
968 */
969 retval = de_thread(current);
970 if (retval)
971 goto out;
972
Matt Helsley925d1c42008-04-29 01:01:36 -0700973 set_mm_exe_file(bprm->mm, bprm->file);
974
Linus Torvalds1da177e2005-04-16 15:20:36 -0700975 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700976 * Release all of the old mmap stuff
977 */
978 retval = exec_mmap(bprm->mm);
979 if (retval)
Al Virofd8328b2008-04-22 05:11:59 -0400980 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700981
982 bprm->mm = NULL; /* We're using it now */
983
984 /* This is the point of no return */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700985 current->sas_ss_sp = current->sas_ss_size = 0;
986
987 if (current->euid == current->uid && current->egid == current->gid)
Kawai, Hidehiro6c5d5232007-07-19 01:48:27 -0700988 set_dumpable(current->mm, 1);
Alan Coxd6e71142005-06-23 00:09:43 -0700989 else
Kawai, Hidehiro6c5d5232007-07-19 01:48:27 -0700990 set_dumpable(current->mm, suid_dumpable);
Alan Coxd6e71142005-06-23 00:09:43 -0700991
Linus Torvalds1da177e2005-04-16 15:20:36 -0700992 name = bprm->filename;
Paolo 'Blaisorblade' Giarrusso36772092005-05-05 16:16:12 -0700993
994 /* Copies the binary name from after last slash */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700995 for (i=0; (ch = *(name++)) != '\0';) {
996 if (ch == '/')
Paolo 'Blaisorblade' Giarrusso36772092005-05-05 16:16:12 -0700997 i = 0; /* overwrite what we wrote */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700998 else
999 if (i < (sizeof(tcomm) - 1))
1000 tcomm[i++] = ch;
1001 }
1002 tcomm[i] = '\0';
1003 set_task_comm(current, tcomm);
1004
1005 current->flags &= ~PF_RANDOMIZE;
1006 flush_thread();
1007
Benjamin Herrenschmidt0551fbd2006-02-28 16:59:19 -08001008 /* Set the new mm task size. We have to do that late because it may
1009 * depend on TIF_32BIT which is only updated in flush_thread() on
1010 * some architectures like powerpc
1011 */
1012 current->mm->task_size = TASK_SIZE;
1013
Marcel Holtmannd2d56c52007-08-17 21:47:58 +02001014 if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) {
1015 suid_keys(current);
1016 set_dumpable(current->mm, suid_dumpable);
1017 current->pdeath_signal = 0;
1018 } else if (file_permission(bprm->file, MAY_READ) ||
1019 (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001020 suid_keys(current);
Kawai, Hidehiro6c5d5232007-07-19 01:48:27 -07001021 set_dumpable(current->mm, suid_dumpable);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001022 }
1023
1024 /* An exec changes our domain. We are no longer part of the thread
1025 group */
1026
1027 current->self_exec_id++;
1028
1029 flush_signal_handlers(current, 0);
1030 flush_old_files(current->files);
1031
1032 return 0;
1033
Linus Torvalds1da177e2005-04-16 15:20:36 -07001034out:
1035 return retval;
1036}
1037
1038EXPORT_SYMBOL(flush_old_exec);
1039
1040/*
1041 * Fill the binprm structure from the inode.
1042 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1043 */
1044int prepare_binprm(struct linux_binprm *bprm)
1045{
1046 int mode;
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001047 struct inode * inode = bprm->file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001048 int retval;
1049
1050 mode = inode->i_mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001051 if (bprm->file->f_op == NULL)
1052 return -EACCES;
1053
1054 bprm->e_uid = current->euid;
1055 bprm->e_gid = current->egid;
1056
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001057 if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001058 /* Set-uid? */
1059 if (mode & S_ISUID) {
1060 current->personality &= ~PER_CLEAR_ON_SETID;
1061 bprm->e_uid = inode->i_uid;
1062 }
1063
1064 /* Set-gid? */
1065 /*
1066 * If setgid is set but no group execute bit then this
1067 * is a candidate for mandatory locking, not a setgid
1068 * executable.
1069 */
1070 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1071 current->personality &= ~PER_CLEAR_ON_SETID;
1072 bprm->e_gid = inode->i_gid;
1073 }
1074 }
1075
1076 /* fill in binprm security blob */
1077 retval = security_bprm_set(bprm);
1078 if (retval)
1079 return retval;
1080
1081 memset(bprm->buf,0,BINPRM_BUF_SIZE);
1082 return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
1083}
1084
1085EXPORT_SYMBOL(prepare_binprm);
1086
Arjan van de Ven858119e2006-01-14 13:20:43 -08001087static int unsafe_exec(struct task_struct *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001088{
Roland McGrath6341c392008-07-25 19:45:44 -07001089 int unsafe = tracehook_unsafe_exec(p);
1090
Linus Torvalds1da177e2005-04-16 15:20:36 -07001091 if (atomic_read(&p->fs->count) > 1 ||
1092 atomic_read(&p->files->count) > 1 ||
1093 atomic_read(&p->sighand->count) > 1)
1094 unsafe |= LSM_UNSAFE_SHARE;
1095
1096 return unsafe;
1097}
1098
1099void compute_creds(struct linux_binprm *bprm)
1100{
1101 int unsafe;
1102
Marcel Holtmannd2d56c52007-08-17 21:47:58 +02001103 if (bprm->e_uid != current->uid) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001104 suid_keys(current);
Marcel Holtmannd2d56c52007-08-17 21:47:58 +02001105 current->pdeath_signal = 0;
1106 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001107 exec_keys(current);
1108
1109 task_lock(current);
1110 unsafe = unsafe_exec(current);
1111 security_bprm_apply_creds(bprm, unsafe);
1112 task_unlock(current);
1113 security_bprm_post_apply_creds(bprm);
1114}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001115EXPORT_SYMBOL(compute_creds);
1116
Nick Piggin4fc75ff2007-05-08 00:25:16 -07001117/*
1118 * Arguments are '\0' separated strings found at the location bprm->p
1119 * points to; chop off the first by relocating brpm->p to right after
1120 * the first '\0' encountered.
1121 */
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001122int remove_arg_zero(struct linux_binprm *bprm)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001123{
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001124 int ret = 0;
1125 unsigned long offset;
1126 char *kaddr;
1127 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001128
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001129 if (!bprm->argc)
1130 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001131
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001132 do {
1133 offset = bprm->p & ~PAGE_MASK;
1134 page = get_arg_page(bprm, bprm->p, 0);
1135 if (!page) {
1136 ret = -EFAULT;
1137 goto out;
1138 }
1139 kaddr = kmap_atomic(page, KM_USER0);
Nick Piggin4fc75ff2007-05-08 00:25:16 -07001140
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001141 for (; offset < PAGE_SIZE && kaddr[offset];
1142 offset++, bprm->p++)
1143 ;
Nick Piggin4fc75ff2007-05-08 00:25:16 -07001144
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001145 kunmap_atomic(kaddr, KM_USER0);
1146 put_arg_page(page);
Nick Piggin4fc75ff2007-05-08 00:25:16 -07001147
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001148 if (offset == PAGE_SIZE)
1149 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1150 } while (offset == PAGE_SIZE);
Nick Piggin4fc75ff2007-05-08 00:25:16 -07001151
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001152 bprm->p++;
1153 bprm->argc--;
1154 ret = 0;
Nick Piggin4fc75ff2007-05-08 00:25:16 -07001155
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001156out:
1157 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001158}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001159EXPORT_SYMBOL(remove_arg_zero);
1160
1161/*
1162 * cycle the list of binary formats handler, until one recognizes the image
1163 */
1164int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1165{
1166 int try,retval;
1167 struct linux_binfmt *fmt;
David Woodhouse702773b2008-06-16 12:11:54 +01001168#ifdef __alpha__
Linus Torvalds1da177e2005-04-16 15:20:36 -07001169 /* handle /sbin/loader.. */
1170 {
1171 struct exec * eh = (struct exec *) bprm->buf;
1172
1173 if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1174 (eh->fh.f_flags & 0x3000) == 0x3000)
1175 {
1176 struct file * file;
1177 unsigned long loader;
1178
1179 allow_write_access(bprm->file);
1180 fput(bprm->file);
1181 bprm->file = NULL;
1182
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001183 loader = bprm->vma->vm_end - sizeof(void *);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184
1185 file = open_exec("/sbin/loader");
1186 retval = PTR_ERR(file);
1187 if (IS_ERR(file))
1188 return retval;
1189
1190 /* Remember if the application is TASO. */
1191 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1192
1193 bprm->file = file;
1194 bprm->loader = loader;
1195 retval = prepare_binprm(bprm);
1196 if (retval<0)
1197 return retval;
1198 /* should call search_binary_handler recursively here,
1199 but it does not matter */
1200 }
1201 }
1202#endif
1203 retval = security_bprm_check(bprm);
1204 if (retval)
1205 return retval;
1206
1207 /* kernel module loader fixup */
1208 /* so we don't try to load run modprobe in kernel space. */
1209 set_fs(USER_DS);
Al Viro473ae302006-04-26 14:04:08 -04001210
1211 retval = audit_bprm(bprm);
1212 if (retval)
1213 return retval;
1214
Linus Torvalds1da177e2005-04-16 15:20:36 -07001215 retval = -ENOENT;
1216 for (try=0; try<2; try++) {
1217 read_lock(&binfmt_lock);
Alexey Dobriyane4dc1b12007-10-16 23:26:03 -07001218 list_for_each_entry(fmt, &formats, lh) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001219 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1220 if (!fn)
1221 continue;
1222 if (!try_module_get(fmt->module))
1223 continue;
1224 read_unlock(&binfmt_lock);
1225 retval = fn(bprm, regs);
1226 if (retval >= 0) {
Roland McGrath6341c392008-07-25 19:45:44 -07001227 tracehook_report_exec(fmt, bprm, regs);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001228 put_binfmt(fmt);
1229 allow_write_access(bprm->file);
1230 if (bprm->file)
1231 fput(bprm->file);
1232 bprm->file = NULL;
1233 current->did_exec = 1;
Matt Helsley9f460802005-11-07 00:59:16 -08001234 proc_exec_connector(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001235 return retval;
1236 }
1237 read_lock(&binfmt_lock);
1238 put_binfmt(fmt);
1239 if (retval != -ENOEXEC || bprm->mm == NULL)
1240 break;
1241 if (!bprm->file) {
1242 read_unlock(&binfmt_lock);
1243 return retval;
1244 }
1245 }
1246 read_unlock(&binfmt_lock);
1247 if (retval != -ENOEXEC || bprm->mm == NULL) {
1248 break;
1249#ifdef CONFIG_KMOD
1250 }else{
1251#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1252 if (printable(bprm->buf[0]) &&
1253 printable(bprm->buf[1]) &&
1254 printable(bprm->buf[2]) &&
1255 printable(bprm->buf[3]))
1256 break; /* -ENOEXEC */
1257 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1258#endif
1259 }
1260 }
1261 return retval;
1262}
1263
1264EXPORT_SYMBOL(search_binary_handler);
1265
Al Viro08a6fac2008-05-10 16:38:25 -04001266void free_bprm(struct linux_binprm *bprm)
1267{
1268 free_arg_pages(bprm);
1269 kfree(bprm);
1270}
1271
Linus Torvalds1da177e2005-04-16 15:20:36 -07001272/*
1273 * sys_execve() executes a new program.
1274 */
1275int do_execve(char * filename,
1276 char __user *__user *argv,
1277 char __user *__user *envp,
1278 struct pt_regs * regs)
1279{
1280 struct linux_binprm *bprm;
1281 struct file *file;
Al Viro3b125382008-04-22 05:31:30 -04001282 struct files_struct *displaced;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001283 int retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001284
Al Viro3b125382008-04-22 05:31:30 -04001285 retval = unshare_files(&displaced);
Al Virofd8328b2008-04-22 05:11:59 -04001286 if (retval)
1287 goto out_ret;
1288
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289 retval = -ENOMEM;
Oliver Neukum11b0b5a2006-03-25 03:08:13 -08001290 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001291 if (!bprm)
Al Virofd8328b2008-04-22 05:11:59 -04001292 goto out_files;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001293
1294 file = open_exec(filename);
1295 retval = PTR_ERR(file);
1296 if (IS_ERR(file))
1297 goto out_kfree;
1298
1299 sched_exec();
1300
Linus Torvalds1da177e2005-04-16 15:20:36 -07001301 bprm->file = file;
1302 bprm->filename = filename;
1303 bprm->interp = filename;
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001304
1305 retval = bprm_mm_init(bprm);
1306 if (retval)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001307 goto out_file;
1308
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001309 bprm->argc = count(argv, MAX_ARG_STRINGS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001310 if ((retval = bprm->argc) < 0)
1311 goto out_mm;
1312
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001313 bprm->envc = count(envp, MAX_ARG_STRINGS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001314 if ((retval = bprm->envc) < 0)
1315 goto out_mm;
1316
1317 retval = security_bprm_alloc(bprm);
1318 if (retval)
1319 goto out;
1320
1321 retval = prepare_binprm(bprm);
1322 if (retval < 0)
1323 goto out;
1324
1325 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1326 if (retval < 0)
1327 goto out;
1328
1329 bprm->exec = bprm->p;
1330 retval = copy_strings(bprm->envc, envp, bprm);
1331 if (retval < 0)
1332 goto out;
1333
1334 retval = copy_strings(bprm->argc, argv, bprm);
1335 if (retval < 0)
1336 goto out;
1337
Oleg Nesterov7b34e422008-07-25 01:47:37 -07001338 current->flags &= ~PF_KTHREAD;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001339 retval = search_binary_handler(bprm,regs);
1340 if (retval >= 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001341 /* execve success */
1342 security_bprm_free(bprm);
1343 acct_update_integrals(current);
Al Viro08a6fac2008-05-10 16:38:25 -04001344 free_bprm(bprm);
Al Viro3b125382008-04-22 05:31:30 -04001345 if (displaced)
1346 put_files_struct(displaced);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001347 return retval;
1348 }
1349
1350out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001351 if (bprm->security)
1352 security_bprm_free(bprm);
1353
1354out_mm:
1355 if (bprm->mm)
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001356 mmput (bprm->mm);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001357
1358out_file:
1359 if (bprm->file) {
1360 allow_write_access(bprm->file);
1361 fput(bprm->file);
1362 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001363out_kfree:
Al Viro08a6fac2008-05-10 16:38:25 -04001364 free_bprm(bprm);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365
Al Virofd8328b2008-04-22 05:11:59 -04001366out_files:
Al Viro3b125382008-04-22 05:31:30 -04001367 if (displaced)
1368 reset_files_struct(displaced);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001369out_ret:
1370 return retval;
1371}
1372
1373int set_binfmt(struct linux_binfmt *new)
1374{
1375 struct linux_binfmt *old = current->binfmt;
1376
1377 if (new) {
1378 if (!try_module_get(new->module))
1379 return -1;
1380 }
1381 current->binfmt = new;
1382 if (old)
1383 module_put(old->module);
1384 return 0;
1385}
1386
1387EXPORT_SYMBOL(set_binfmt);
1388
Linus Torvalds1da177e2005-04-16 15:20:36 -07001389/* format_corename will inspect the pattern parameter, and output a
1390 * name into corename, which must have space for at least
1391 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1392 */
Oleg Nesterov565b9b12008-07-25 01:47:47 -07001393static int format_corename(char *corename, int nr_threads, long signr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001394{
Oleg Nesterov565b9b12008-07-25 01:47:47 -07001395 const char *pat_ptr = core_pattern;
1396 int ispipe = (*pat_ptr == '|');
Linus Torvalds1da177e2005-04-16 15:20:36 -07001397 char *out_ptr = corename;
1398 char *const out_end = corename + CORENAME_MAX_SIZE;
1399 int rc;
1400 int pid_in_pattern = 0;
1401
1402 /* Repeat as long as we have more pattern to process and more output
1403 space */
1404 while (*pat_ptr) {
1405 if (*pat_ptr != '%') {
1406 if (out_ptr == out_end)
1407 goto out;
1408 *out_ptr++ = *pat_ptr++;
1409 } else {
1410 switch (*++pat_ptr) {
1411 case 0:
1412 goto out;
1413 /* Double percent, output one percent */
1414 case '%':
1415 if (out_ptr == out_end)
1416 goto out;
1417 *out_ptr++ = '%';
1418 break;
1419 /* pid */
1420 case 'p':
1421 pid_in_pattern = 1;
1422 rc = snprintf(out_ptr, out_end - out_ptr,
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001423 "%d", task_tgid_vnr(current));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001424 if (rc > out_end - out_ptr)
1425 goto out;
1426 out_ptr += rc;
1427 break;
1428 /* uid */
1429 case 'u':
1430 rc = snprintf(out_ptr, out_end - out_ptr,
1431 "%d", current->uid);
1432 if (rc > out_end - out_ptr)
1433 goto out;
1434 out_ptr += rc;
1435 break;
1436 /* gid */
1437 case 'g':
1438 rc = snprintf(out_ptr, out_end - out_ptr,
1439 "%d", current->gid);
1440 if (rc > out_end - out_ptr)
1441 goto out;
1442 out_ptr += rc;
1443 break;
1444 /* signal that caused the coredump */
1445 case 's':
1446 rc = snprintf(out_ptr, out_end - out_ptr,
1447 "%ld", signr);
1448 if (rc > out_end - out_ptr)
1449 goto out;
1450 out_ptr += rc;
1451 break;
1452 /* UNIX time of coredump */
1453 case 't': {
1454 struct timeval tv;
1455 do_gettimeofday(&tv);
1456 rc = snprintf(out_ptr, out_end - out_ptr,
1457 "%lu", tv.tv_sec);
1458 if (rc > out_end - out_ptr)
1459 goto out;
1460 out_ptr += rc;
1461 break;
1462 }
1463 /* hostname */
1464 case 'h':
1465 down_read(&uts_sem);
1466 rc = snprintf(out_ptr, out_end - out_ptr,
Serge E. Hallyne9ff3992006-10-02 02:18:11 -07001467 "%s", utsname()->nodename);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001468 up_read(&uts_sem);
1469 if (rc > out_end - out_ptr)
1470 goto out;
1471 out_ptr += rc;
1472 break;
1473 /* executable */
1474 case 'e':
1475 rc = snprintf(out_ptr, out_end - out_ptr,
1476 "%s", current->comm);
1477 if (rc > out_end - out_ptr)
1478 goto out;
1479 out_ptr += rc;
1480 break;
Neil Horman74aadce2007-10-16 23:26:35 -07001481 /* core limit size */
1482 case 'c':
1483 rc = snprintf(out_ptr, out_end - out_ptr,
1484 "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1485 if (rc > out_end - out_ptr)
1486 goto out;
1487 out_ptr += rc;
1488 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001489 default:
1490 break;
1491 }
1492 ++pat_ptr;
1493 }
1494 }
1495 /* Backward compatibility with core_uses_pid:
1496 *
1497 * If core_pattern does not include a %p (as is the default)
1498 * and core_uses_pid is set, then .%pid will be appended to
Alan Coxc4bbafd2007-04-16 22:53:13 -07001499 * the filename. Do not do this for piped commands. */
1500 if (!ispipe && !pid_in_pattern
Oleg Nesterov565b9b12008-07-25 01:47:47 -07001501 && (core_uses_pid || nr_threads)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001502 rc = snprintf(out_ptr, out_end - out_ptr,
Pavel Emelyanovb4888932007-10-18 23:40:14 -07001503 ".%d", task_tgid_vnr(current));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001504 if (rc > out_end - out_ptr)
1505 goto out;
1506 out_ptr += rc;
1507 }
Alan Coxc4bbafd2007-04-16 22:53:13 -07001508out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001509 *out_ptr = 0;
Alan Coxc4bbafd2007-04-16 22:53:13 -07001510 return ispipe;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001511}
1512
Oleg Nesterov8cd9c242008-07-25 01:47:42 -07001513static int zap_process(struct task_struct *start)
Oleg Nesterovaceecc02006-06-26 00:26:05 -07001514{
1515 struct task_struct *t;
Oleg Nesterov8cd9c242008-07-25 01:47:42 -07001516 int nr = 0;
Oleg Nesterov281de332006-06-26 00:26:06 -07001517
Oleg Nesterovd5f70c02006-06-26 00:26:07 -07001518 start->signal->flags = SIGNAL_GROUP_EXIT;
1519 start->signal->group_stop_count = 0;
Oleg Nesterovaceecc02006-06-26 00:26:05 -07001520
1521 t = start;
1522 do {
1523 if (t != current && t->mm) {
Oleg Nesterov281de332006-06-26 00:26:06 -07001524 sigaddset(&t->pending.signal, SIGKILL);
1525 signal_wake_up(t, 1);
Oleg Nesterov8cd9c242008-07-25 01:47:42 -07001526 nr++;
Oleg Nesterovaceecc02006-06-26 00:26:05 -07001527 }
Oleg Nesterove4901f92008-07-25 01:47:31 -07001528 } while_each_thread(start, t);
Oleg Nesterov8cd9c242008-07-25 01:47:42 -07001529
1530 return nr;
Oleg Nesterovaceecc02006-06-26 00:26:05 -07001531}
1532
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001533static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
Oleg Nesterov8cd9c242008-07-25 01:47:42 -07001534 struct core_state *core_state, int exit_code)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001535{
1536 struct task_struct *g, *p;
Oleg Nesterov5debfa62006-06-26 00:26:09 -07001537 unsigned long flags;
Oleg Nesterov8cd9c242008-07-25 01:47:42 -07001538 int nr = -EAGAIN;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001539
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001540 spin_lock_irq(&tsk->sighand->siglock);
Oleg Nesteroved5d2ca2008-02-04 22:27:24 -08001541 if (!signal_group_exit(tsk->signal)) {
Oleg Nesterov8cd9c242008-07-25 01:47:42 -07001542 mm->core_state = core_state;
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001543 tsk->signal->group_exit_code = exit_code;
Oleg Nesterov8cd9c242008-07-25 01:47:42 -07001544 nr = zap_process(tsk);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001545 }
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001546 spin_unlock_irq(&tsk->sighand->siglock);
Oleg Nesterov8cd9c242008-07-25 01:47:42 -07001547 if (unlikely(nr < 0))
1548 return nr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001549
Oleg Nesterov8cd9c242008-07-25 01:47:42 -07001550 if (atomic_read(&mm->mm_users) == nr + 1)
Oleg Nesterov5debfa62006-06-26 00:26:09 -07001551 goto done;
Oleg Nesterove4901f92008-07-25 01:47:31 -07001552 /*
1553 * We should find and kill all tasks which use this mm, and we should
Oleg Nesterov999d9fc2008-07-25 01:47:41 -07001554 * count them correctly into ->nr_threads. We don't take tasklist
Oleg Nesterove4901f92008-07-25 01:47:31 -07001555 * lock, but this is safe wrt:
1556 *
1557 * fork:
1558 * None of sub-threads can fork after zap_process(leader). All
1559 * processes which were created before this point should be
1560 * visible to zap_threads() because copy_process() adds the new
1561 * process to the tail of init_task.tasks list, and lock/unlock
1562 * of ->siglock provides a memory barrier.
1563 *
1564 * do_exit:
1565 * The caller holds mm->mmap_sem. This means that the task which
1566 * uses this mm can't pass exit_mm(), so it can't exit or clear
1567 * its ->mm.
1568 *
1569 * de_thread:
1570 * It does list_replace_rcu(&leader->tasks, &current->tasks),
1571 * we must see either old or new leader, this does not matter.
1572 * However, it can change p->sighand, so lock_task_sighand(p)
1573 * must be used. Since p->mm != NULL and we hold ->mmap_sem
1574 * it can't fail.
1575 *
1576 * Note also that "g" can be the old leader with ->mm == NULL
1577 * and already unhashed and thus removed from ->thread_group.
1578 * This is OK, __unhash_process()->list_del_rcu() does not
1579 * clear the ->next pointer, we will find the new leader via
1580 * next_thread().
1581 */
Oleg Nesterov7b1c6152006-06-26 00:26:08 -07001582 rcu_read_lock();
Oleg Nesterovaceecc02006-06-26 00:26:05 -07001583 for_each_process(g) {
Oleg Nesterov5debfa62006-06-26 00:26:09 -07001584 if (g == tsk->group_leader)
1585 continue;
Oleg Nesterov15b9f362008-07-25 01:47:39 -07001586 if (g->flags & PF_KTHREAD)
1587 continue;
Oleg Nesterovaceecc02006-06-26 00:26:05 -07001588 p = g;
1589 do {
1590 if (p->mm) {
Oleg Nesterov15b9f362008-07-25 01:47:39 -07001591 if (unlikely(p->mm == mm)) {
Oleg Nesterov5debfa62006-06-26 00:26:09 -07001592 lock_task_sighand(p, &flags);
Oleg Nesterov8cd9c242008-07-25 01:47:42 -07001593 nr += zap_process(p);
Oleg Nesterov5debfa62006-06-26 00:26:09 -07001594 unlock_task_sighand(p, &flags);
1595 }
Oleg Nesterovaceecc02006-06-26 00:26:05 -07001596 break;
1597 }
Oleg Nesterove4901f92008-07-25 01:47:31 -07001598 } while_each_thread(g, p);
Oleg Nesterovaceecc02006-06-26 00:26:05 -07001599 }
Oleg Nesterov7b1c6152006-06-26 00:26:08 -07001600 rcu_read_unlock();
Oleg Nesterov5debfa62006-06-26 00:26:09 -07001601done:
Oleg Nesterovc5f1cc82008-07-25 01:47:42 -07001602 atomic_set(&core_state->nr_threads, nr);
Oleg Nesterov8cd9c242008-07-25 01:47:42 -07001603 return nr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604}
1605
Oleg Nesterov9d5b3272008-07-25 01:47:43 -07001606static int coredump_wait(int exit_code, struct core_state *core_state)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001607{
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001608 struct task_struct *tsk = current;
1609 struct mm_struct *mm = tsk->mm;
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001610 struct completion *vfork_done;
Oleg Nesterov2384f552005-10-30 15:02:47 -08001611 int core_waiters;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001612
Oleg Nesterov9d5b3272008-07-25 01:47:43 -07001613 init_completion(&core_state->startup);
Oleg Nesterovb564daf2008-07-25 01:47:44 -07001614 core_state->dumper.task = tsk;
1615 core_state->dumper.next = NULL;
Oleg Nesterov9d5b3272008-07-25 01:47:43 -07001616 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
Oleg Nesterov2384f552005-10-30 15:02:47 -08001617 up_write(&mm->mmap_sem);
1618
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001619 if (unlikely(core_waiters < 0))
1620 goto fail;
1621
1622 /*
1623 * Make sure nobody is waiting for us to release the VM,
1624 * otherwise we can deadlock when we wait on each other
1625 */
1626 vfork_done = tsk->vfork_done;
1627 if (vfork_done) {
1628 tsk->vfork_done = NULL;
1629 complete(vfork_done);
1630 }
1631
Oleg Nesterov2384f552005-10-30 15:02:47 -08001632 if (core_waiters)
Oleg Nesterov9d5b3272008-07-25 01:47:43 -07001633 wait_for_completion(&core_state->startup);
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001634fail:
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001635 return core_waiters;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001636}
1637
Oleg Nesterova94e2d42008-07-25 01:47:46 -07001638static void coredump_finish(struct mm_struct *mm)
1639{
1640 struct core_thread *curr, *next;
1641 struct task_struct *task;
1642
1643 next = mm->core_state->dumper.next;
1644 while ((curr = next) != NULL) {
1645 next = curr->next;
1646 task = curr->task;
1647 /*
1648 * see exit_mm(), curr->task must not see
1649 * ->task == NULL before we read ->next.
1650 */
1651 smp_mb();
1652 curr->task = NULL;
1653 wake_up_process(task);
1654 }
1655
1656 mm->core_state = NULL;
1657}
1658
Kawai, Hidehiro6c5d5232007-07-19 01:48:27 -07001659/*
1660 * set_dumpable converts traditional three-value dumpable to two flags and
1661 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1662 * these bits are not changed atomically. So get_dumpable can observe the
1663 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1664 * return either old dumpable or new one by paying attention to the order of
1665 * modifying the bits.
1666 *
1667 * dumpable | mm->flags (binary)
1668 * old new | initial interim final
1669 * ---------+-----------------------
1670 * 0 1 | 00 01 01
1671 * 0 2 | 00 10(*) 11
1672 * 1 0 | 01 00 00
1673 * 1 2 | 01 11 11
1674 * 2 0 | 11 10(*) 00
1675 * 2 1 | 11 11 01
1676 *
1677 * (*) get_dumpable regards interim value of 10 as 11.
1678 */
1679void set_dumpable(struct mm_struct *mm, int value)
1680{
1681 switch (value) {
1682 case 0:
1683 clear_bit(MMF_DUMPABLE, &mm->flags);
1684 smp_wmb();
1685 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1686 break;
1687 case 1:
1688 set_bit(MMF_DUMPABLE, &mm->flags);
1689 smp_wmb();
1690 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1691 break;
1692 case 2:
1693 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1694 smp_wmb();
1695 set_bit(MMF_DUMPABLE, &mm->flags);
1696 break;
1697 }
1698}
Kawai, Hidehiro6c5d5232007-07-19 01:48:27 -07001699
1700int get_dumpable(struct mm_struct *mm)
1701{
1702 int ret;
1703
1704 ret = mm->flags & 0x3;
1705 return (ret >= 2) ? 2 : ret;
1706}
1707
Linus Torvalds1da177e2005-04-16 15:20:36 -07001708int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1709{
Oleg Nesterov9d5b3272008-07-25 01:47:43 -07001710 struct core_state core_state;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001711 char corename[CORENAME_MAX_SIZE + 1];
1712 struct mm_struct *mm = current->mm;
1713 struct linux_binfmt * binfmt;
1714 struct inode * inode;
1715 struct file * file;
1716 int retval = 0;
Alan Coxd6e71142005-06-23 00:09:43 -07001717 int fsuid = current->fsuid;
1718 int flag = 0;
Andi Kleend025c9d2006-09-30 23:29:28 -07001719 int ispipe = 0;
Neil Horman7dc0b222007-10-16 23:26:34 -07001720 unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
Neil Horman74aadce2007-10-16 23:26:35 -07001721 char **helper_argv = NULL;
1722 int helper_argc = 0;
1723 char *delimit;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001724
Steve Grubb0a4ff8c2007-04-19 10:28:21 -04001725 audit_core_dumps(signr);
1726
Linus Torvalds1da177e2005-04-16 15:20:36 -07001727 binfmt = current->binfmt;
1728 if (!binfmt || !binfmt->core_dump)
1729 goto fail;
1730 down_write(&mm->mmap_sem);
Roland McGrath00ec99d2007-11-11 19:13:43 -08001731 /*
1732 * If another thread got here first, or we are not dumpable, bail out.
1733 */
Oleg Nesterov999d9fc2008-07-25 01:47:41 -07001734 if (mm->core_state || !get_dumpable(mm)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001735 up_write(&mm->mmap_sem);
1736 goto fail;
1737 }
Alan Coxd6e71142005-06-23 00:09:43 -07001738
1739 /*
1740 * We cannot trust fsuid as being the "true" uid of the
1741 * process nor do we know its entire history. We only know it
1742 * was tainted so we dump it as root in mode 2.
1743 */
Kawai, Hidehiro6c5d5232007-07-19 01:48:27 -07001744 if (get_dumpable(mm) == 2) { /* Setuid core dump mode */
Alan Coxd6e71142005-06-23 00:09:43 -07001745 flag = O_EXCL; /* Stop rewrite attacks */
1746 current->fsuid = 0; /* Dump root private */
1747 }
Oleg Nesterov1291cf42005-10-30 15:02:54 -08001748
Oleg Nesterov9d5b3272008-07-25 01:47:43 -07001749 retval = coredump_wait(exit_code, &core_state);
Oleg Nesterovdcf560c2006-06-26 00:26:08 -07001750 if (retval < 0)
Oleg Nesterov1291cf42005-10-30 15:02:54 -08001751 goto fail;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001752
1753 /*
1754 * Clear any false indication of pending signals that might
1755 * be seen by the filesystem code called to write the core file.
1756 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001757 clear_thread_flag(TIF_SIGPENDING);
1758
Linus Torvalds1da177e2005-04-16 15:20:36 -07001759 /*
1760 * lock_kernel() because format_corename() is controlled by sysctl, which
1761 * uses lock_kernel()
1762 */
1763 lock_kernel();
Oleg Nesterov565b9b12008-07-25 01:47:47 -07001764 ispipe = format_corename(corename, retval, signr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001765 unlock_kernel();
Neil Horman7dc0b222007-10-16 23:26:34 -07001766 /*
1767 * Don't bother to check the RLIMIT_CORE value if core_pattern points
1768 * to a pipe. Since we're not writing directly to the filesystem
1769 * RLIMIT_CORE doesn't really apply, as no actual core file will be
1770 * created unless the pipe reader choses to write out the core file
1771 * at which point file size limits and permissions will be imposed
1772 * as it does with any other process
1773 */
Neil Horman74aadce2007-10-16 23:26:35 -07001774 if ((!ispipe) && (core_limit < binfmt->min_coredump))
Neil Horman7dc0b222007-10-16 23:26:34 -07001775 goto fail_unlock;
1776
Alan Coxc4bbafd2007-04-16 22:53:13 -07001777 if (ispipe) {
Neil Horman74aadce2007-10-16 23:26:35 -07001778 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1779 /* Terminate the string before the first option */
1780 delimit = strchr(corename, ' ');
1781 if (delimit)
1782 *delimit = '\0';
Neil Horman32321132007-10-16 23:26:36 -07001783 delimit = strrchr(helper_argv[0], '/');
1784 if (delimit)
1785 delimit++;
1786 else
1787 delimit = helper_argv[0];
1788 if (!strcmp(delimit, current->comm)) {
1789 printk(KERN_NOTICE "Recursive core dump detected, "
1790 "aborting\n");
1791 goto fail_unlock;
1792 }
1793
1794 core_limit = RLIM_INFINITY;
1795
Andi Kleend025c9d2006-09-30 23:29:28 -07001796 /* SIGPIPE can happen, but it's just never processed */
Neil Horman32321132007-10-16 23:26:36 -07001797 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
1798 &file)) {
Andi Kleend025c9d2006-09-30 23:29:28 -07001799 printk(KERN_INFO "Core dump to %s pipe failed\n",
1800 corename);
1801 goto fail_unlock;
1802 }
Andi Kleend025c9d2006-09-30 23:29:28 -07001803 } else
1804 file = filp_open(corename,
Alexey Dobriyan6d4df672006-12-06 20:40:39 -08001805 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1806 0600);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001807 if (IS_ERR(file))
1808 goto fail_unlock;
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001809 inode = file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001810 if (inode->i_nlink > 1)
1811 goto close_fail; /* multiple links - don't dump */
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001812 if (!ispipe && d_unhashed(file->f_path.dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001813 goto close_fail;
1814
Andi Kleend025c9d2006-09-30 23:29:28 -07001815 /* AK: actually i see no reason to not allow this for named pipes etc.,
1816 but keep the previous behaviour for now. */
1817 if (!ispipe && !S_ISREG(inode->i_mode))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001818 goto close_fail;
Ingo Molnarc46f7392007-11-28 13:59:18 +01001819 /*
1820 * Dont allow local users get cute and trick others to coredump
1821 * into their pre-created files:
1822 */
1823 if (inode->i_uid != current->fsuid)
1824 goto close_fail;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001825 if (!file->f_op)
1826 goto close_fail;
1827 if (!file->f_op->write)
1828 goto close_fail;
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001829 if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001830 goto close_fail;
1831
Neil Horman7dc0b222007-10-16 23:26:34 -07001832 retval = binfmt->core_dump(signr, regs, file, core_limit);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001833
1834 if (retval)
1835 current->signal->group_exit_code |= 0x80;
1836close_fail:
1837 filp_close(file, NULL);
1838fail_unlock:
Neil Horman74aadce2007-10-16 23:26:35 -07001839 if (helper_argv)
1840 argv_free(helper_argv);
1841
Alan Coxd6e71142005-06-23 00:09:43 -07001842 current->fsuid = fsuid;
Oleg Nesterova94e2d42008-07-25 01:47:46 -07001843 coredump_finish(mm);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001844fail:
1845 return retval;
1846}