V4L/DVB (12901): DiB0700: add support for STK807XP and STK807XPVR
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / exec.c
blob172ceb6edde4df6ff8520cd9951b3bc2ca86b2c2
1 /*
2 * linux/fs/exec.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
7 /*
8 * #!-checking implemented by tytso.
9 */
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.
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.
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.
25 #include <linux/slab.h>
26 #include <linux/file.h>
27 #include <linux/fdtable.h>
28 #include <linux/mm.h>
29 #include <linux/stat.h>
30 #include <linux/fcntl.h>
31 #include <linux/smp_lock.h>
32 #include <linux/swap.h>
33 #include <linux/string.h>
34 #include <linux/init.h>
35 #include <linux/pagemap.h>
36 #include <linux/perf_counter.h>
37 #include <linux/highmem.h>
38 #include <linux/spinlock.h>
39 #include <linux/key.h>
40 #include <linux/personality.h>
41 #include <linux/binfmts.h>
42 #include <linux/utsname.h>
43 #include <linux/pid_namespace.h>
44 #include <linux/module.h>
45 #include <linux/namei.h>
46 #include <linux/proc_fs.h>
47 #include <linux/mount.h>
48 #include <linux/security.h>
49 #include <linux/ima.h>
50 #include <linux/syscalls.h>
51 #include <linux/tsacct_kern.h>
52 #include <linux/cn_proc.h>
53 #include <linux/audit.h>
54 #include <linux/tracehook.h>
55 #include <linux/kmod.h>
56 #include <linux/fsnotify.h>
57 #include <linux/fs_struct.h>
59 #include <asm/uaccess.h>
60 #include <asm/mmu_context.h>
61 #include <asm/tlb.h>
62 #include "internal.h"
64 int core_uses_pid;
65 char core_pattern[CORENAME_MAX_SIZE] = "core";
66 int suid_dumpable = 0;
68 /* The maximal length of core_pattern is also specified in sysctl.c */
70 static LIST_HEAD(formats);
71 static DEFINE_RWLOCK(binfmt_lock);
73 int __register_binfmt(struct linux_binfmt * fmt, int insert)
75 if (!fmt)
76 return -EINVAL;
77 write_lock(&binfmt_lock);
78 insert ? list_add(&fmt->lh, &formats) :
79 list_add_tail(&fmt->lh, &formats);
80 write_unlock(&binfmt_lock);
81 return 0;
84 EXPORT_SYMBOL(__register_binfmt);
86 void unregister_binfmt(struct linux_binfmt * fmt)
88 write_lock(&binfmt_lock);
89 list_del(&fmt->lh);
90 write_unlock(&binfmt_lock);
93 EXPORT_SYMBOL(unregister_binfmt);
95 static inline void put_binfmt(struct linux_binfmt * fmt)
97 module_put(fmt->module);
101 * Note that a shared library must be both readable and executable due to
102 * security reasons.
104 * Also note that we take the address to load from from the file itself.
106 SYSCALL_DEFINE1(uselib, const char __user *, library)
108 struct file *file;
109 char *tmp = getname(library);
110 int error = PTR_ERR(tmp);
112 if (IS_ERR(tmp))
113 goto out;
115 file = do_filp_open(AT_FDCWD, tmp,
116 O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
117 MAY_READ | MAY_EXEC | MAY_OPEN);
118 putname(tmp);
119 error = PTR_ERR(file);
120 if (IS_ERR(file))
121 goto out;
123 error = -EINVAL;
124 if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
125 goto exit;
127 error = -EACCES;
128 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
129 goto exit;
131 fsnotify_open(file->f_path.dentry);
133 error = -ENOEXEC;
134 if(file->f_op) {
135 struct linux_binfmt * fmt;
137 read_lock(&binfmt_lock);
138 list_for_each_entry(fmt, &formats, lh) {
139 if (!fmt->load_shlib)
140 continue;
141 if (!try_module_get(fmt->module))
142 continue;
143 read_unlock(&binfmt_lock);
144 error = fmt->load_shlib(file);
145 read_lock(&binfmt_lock);
146 put_binfmt(fmt);
147 if (error != -ENOEXEC)
148 break;
150 read_unlock(&binfmt_lock);
152 exit:
153 fput(file);
154 out:
155 return error;
158 #ifdef CONFIG_MMU
160 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
161 int write)
163 struct page *page;
164 int ret;
166 #ifdef CONFIG_STACK_GROWSUP
167 if (write) {
168 ret = expand_stack_downwards(bprm->vma, pos);
169 if (ret < 0)
170 return NULL;
172 #endif
173 ret = get_user_pages(current, bprm->mm, pos,
174 1, write, 1, &page, NULL);
175 if (ret <= 0)
176 return NULL;
178 if (write) {
179 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
180 struct rlimit *rlim;
183 * We've historically supported up to 32 pages (ARG_MAX)
184 * of argument strings even with small stacks
186 if (size <= ARG_MAX)
187 return page;
190 * Limit to 1/4-th the stack size for the argv+env strings.
191 * This ensures that:
192 * - the remaining binfmt code will not run out of stack space,
193 * - the program will have a reasonable amount of stack left
194 * to work from.
196 rlim = current->signal->rlim;
197 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
198 put_page(page);
199 return NULL;
203 return page;
206 static void put_arg_page(struct page *page)
208 put_page(page);
211 static void free_arg_page(struct linux_binprm *bprm, int i)
215 static void free_arg_pages(struct linux_binprm *bprm)
219 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
220 struct page *page)
222 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
225 static int __bprm_mm_init(struct linux_binprm *bprm)
227 int err;
228 struct vm_area_struct *vma = NULL;
229 struct mm_struct *mm = bprm->mm;
231 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
232 if (!vma)
233 return -ENOMEM;
235 down_write(&mm->mmap_sem);
236 vma->vm_mm = mm;
239 * Place the stack at the largest stack address the architecture
240 * supports. Later, we'll move this to an appropriate place. We don't
241 * use STACK_TOP because that can depend on attributes which aren't
242 * configured yet.
244 vma->vm_end = STACK_TOP_MAX;
245 vma->vm_start = vma->vm_end - PAGE_SIZE;
246 vma->vm_flags = VM_STACK_FLAGS;
247 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
248 err = insert_vm_struct(mm, vma);
249 if (err)
250 goto err;
252 mm->stack_vm = mm->total_vm = 1;
253 up_write(&mm->mmap_sem);
254 bprm->p = vma->vm_end - sizeof(void *);
255 return 0;
256 err:
257 up_write(&mm->mmap_sem);
258 bprm->vma = NULL;
259 kmem_cache_free(vm_area_cachep, vma);
260 return err;
263 static bool valid_arg_len(struct linux_binprm *bprm, long len)
265 return len <= MAX_ARG_STRLEN;
268 #else
270 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
271 int write)
273 struct page *page;
275 page = bprm->page[pos / PAGE_SIZE];
276 if (!page && write) {
277 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
278 if (!page)
279 return NULL;
280 bprm->page[pos / PAGE_SIZE] = page;
283 return page;
286 static void put_arg_page(struct page *page)
290 static void free_arg_page(struct linux_binprm *bprm, int i)
292 if (bprm->page[i]) {
293 __free_page(bprm->page[i]);
294 bprm->page[i] = NULL;
298 static void free_arg_pages(struct linux_binprm *bprm)
300 int i;
302 for (i = 0; i < MAX_ARG_PAGES; i++)
303 free_arg_page(bprm, i);
306 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
307 struct page *page)
311 static int __bprm_mm_init(struct linux_binprm *bprm)
313 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
314 return 0;
317 static bool valid_arg_len(struct linux_binprm *bprm, long len)
319 return len <= bprm->p;
322 #endif /* CONFIG_MMU */
325 * Create a new mm_struct and populate it with a temporary stack
326 * vm_area_struct. We don't have enough context at this point to set the stack
327 * flags, permissions, and offset, so we use temporary values. We'll update
328 * them later in setup_arg_pages().
330 int bprm_mm_init(struct linux_binprm *bprm)
332 int err;
333 struct mm_struct *mm = NULL;
335 bprm->mm = mm = mm_alloc();
336 err = -ENOMEM;
337 if (!mm)
338 goto err;
340 err = init_new_context(current, mm);
341 if (err)
342 goto err;
344 err = __bprm_mm_init(bprm);
345 if (err)
346 goto err;
348 return 0;
350 err:
351 if (mm) {
352 bprm->mm = NULL;
353 mmdrop(mm);
356 return err;
360 * count() counts the number of strings in array ARGV.
362 static int count(char __user * __user * argv, int max)
364 int i = 0;
366 if (argv != NULL) {
367 for (;;) {
368 char __user * p;
370 if (get_user(p, argv))
371 return -EFAULT;
372 if (!p)
373 break;
374 argv++;
375 if (i++ >= max)
376 return -E2BIG;
377 cond_resched();
380 return i;
384 * 'copy_strings()' copies argument/environment strings from the old
385 * processes's memory to the new process's stack. The call to get_user_pages()
386 * ensures the destination page is created and not swapped out.
388 static int copy_strings(int argc, char __user * __user * argv,
389 struct linux_binprm *bprm)
391 struct page *kmapped_page = NULL;
392 char *kaddr = NULL;
393 unsigned long kpos = 0;
394 int ret;
396 while (argc-- > 0) {
397 char __user *str;
398 int len;
399 unsigned long pos;
401 if (get_user(str, argv+argc) ||
402 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
403 ret = -EFAULT;
404 goto out;
407 if (!valid_arg_len(bprm, len)) {
408 ret = -E2BIG;
409 goto out;
412 /* We're going to work our way backwords. */
413 pos = bprm->p;
414 str += len;
415 bprm->p -= len;
417 while (len > 0) {
418 int offset, bytes_to_copy;
420 offset = pos % PAGE_SIZE;
421 if (offset == 0)
422 offset = PAGE_SIZE;
424 bytes_to_copy = offset;
425 if (bytes_to_copy > len)
426 bytes_to_copy = len;
428 offset -= bytes_to_copy;
429 pos -= bytes_to_copy;
430 str -= bytes_to_copy;
431 len -= bytes_to_copy;
433 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
434 struct page *page;
436 page = get_arg_page(bprm, pos, 1);
437 if (!page) {
438 ret = -E2BIG;
439 goto out;
442 if (kmapped_page) {
443 flush_kernel_dcache_page(kmapped_page);
444 kunmap(kmapped_page);
445 put_arg_page(kmapped_page);
447 kmapped_page = page;
448 kaddr = kmap(kmapped_page);
449 kpos = pos & PAGE_MASK;
450 flush_arg_page(bprm, kpos, kmapped_page);
452 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
453 ret = -EFAULT;
454 goto out;
458 ret = 0;
459 out:
460 if (kmapped_page) {
461 flush_kernel_dcache_page(kmapped_page);
462 kunmap(kmapped_page);
463 put_arg_page(kmapped_page);
465 return ret;
469 * Like copy_strings, but get argv and its values from kernel memory.
471 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
473 int r;
474 mm_segment_t oldfs = get_fs();
475 set_fs(KERNEL_DS);
476 r = copy_strings(argc, (char __user * __user *)argv, bprm);
477 set_fs(oldfs);
478 return r;
480 EXPORT_SYMBOL(copy_strings_kernel);
482 #ifdef CONFIG_MMU
485 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
486 * the binfmt code determines where the new stack should reside, we shift it to
487 * its final location. The process proceeds as follows:
489 * 1) Use shift to calculate the new vma endpoints.
490 * 2) Extend vma to cover both the old and new ranges. This ensures the
491 * arguments passed to subsequent functions are consistent.
492 * 3) Move vma's page tables to the new range.
493 * 4) Free up any cleared pgd range.
494 * 5) Shrink the vma to cover only the new range.
496 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
498 struct mm_struct *mm = vma->vm_mm;
499 unsigned long old_start = vma->vm_start;
500 unsigned long old_end = vma->vm_end;
501 unsigned long length = old_end - old_start;
502 unsigned long new_start = old_start - shift;
503 unsigned long new_end = old_end - shift;
504 struct mmu_gather *tlb;
506 BUG_ON(new_start > new_end);
509 * ensure there are no vmas between where we want to go
510 * and where we are
512 if (vma != find_vma(mm, new_start))
513 return -EFAULT;
516 * cover the whole range: [new_start, old_end)
518 vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
521 * move the page tables downwards, on failure we rely on
522 * process cleanup to remove whatever mess we made.
524 if (length != move_page_tables(vma, old_start,
525 vma, new_start, length))
526 return -ENOMEM;
528 lru_add_drain();
529 tlb = tlb_gather_mmu(mm, 0);
530 if (new_end > old_start) {
532 * when the old and new regions overlap clear from new_end.
534 free_pgd_range(tlb, new_end, old_end, new_end,
535 vma->vm_next ? vma->vm_next->vm_start : 0);
536 } else {
538 * otherwise, clean from old_start; this is done to not touch
539 * the address space in [new_end, old_start) some architectures
540 * have constraints on va-space that make this illegal (IA64) -
541 * for the others its just a little faster.
543 free_pgd_range(tlb, old_start, old_end, new_end,
544 vma->vm_next ? vma->vm_next->vm_start : 0);
546 tlb_finish_mmu(tlb, new_end, old_end);
549 * shrink the vma to just the new range.
551 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
553 return 0;
556 #define EXTRA_STACK_VM_PAGES 20 /* random */
559 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
560 * the stack is optionally relocated, and some extra space is added.
562 int setup_arg_pages(struct linux_binprm *bprm,
563 unsigned long stack_top,
564 int executable_stack)
566 unsigned long ret;
567 unsigned long stack_shift;
568 struct mm_struct *mm = current->mm;
569 struct vm_area_struct *vma = bprm->vma;
570 struct vm_area_struct *prev = NULL;
571 unsigned long vm_flags;
572 unsigned long stack_base;
574 #ifdef CONFIG_STACK_GROWSUP
575 /* Limit stack size to 1GB */
576 stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
577 if (stack_base > (1 << 30))
578 stack_base = 1 << 30;
580 /* Make sure we didn't let the argument array grow too large. */
581 if (vma->vm_end - vma->vm_start > stack_base)
582 return -ENOMEM;
584 stack_base = PAGE_ALIGN(stack_top - stack_base);
586 stack_shift = vma->vm_start - stack_base;
587 mm->arg_start = bprm->p - stack_shift;
588 bprm->p = vma->vm_end - stack_shift;
589 #else
590 stack_top = arch_align_stack(stack_top);
591 stack_top = PAGE_ALIGN(stack_top);
592 stack_shift = vma->vm_end - stack_top;
594 bprm->p -= stack_shift;
595 mm->arg_start = bprm->p;
596 #endif
598 if (bprm->loader)
599 bprm->loader -= stack_shift;
600 bprm->exec -= stack_shift;
602 down_write(&mm->mmap_sem);
603 vm_flags = VM_STACK_FLAGS;
606 * Adjust stack execute permissions; explicitly enable for
607 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
608 * (arch default) otherwise.
610 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
611 vm_flags |= VM_EXEC;
612 else if (executable_stack == EXSTACK_DISABLE_X)
613 vm_flags &= ~VM_EXEC;
614 vm_flags |= mm->def_flags;
616 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
617 vm_flags);
618 if (ret)
619 goto out_unlock;
620 BUG_ON(prev != vma);
622 /* Move stack pages down in memory. */
623 if (stack_shift) {
624 ret = shift_arg_pages(vma, stack_shift);
625 if (ret) {
626 up_write(&mm->mmap_sem);
627 return ret;
631 #ifdef CONFIG_STACK_GROWSUP
632 stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
633 #else
634 stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
635 #endif
636 ret = expand_stack(vma, stack_base);
637 if (ret)
638 ret = -EFAULT;
640 out_unlock:
641 up_write(&mm->mmap_sem);
642 return 0;
644 EXPORT_SYMBOL(setup_arg_pages);
646 #endif /* CONFIG_MMU */
648 struct file *open_exec(const char *name)
650 struct file *file;
651 int err;
653 file = do_filp_open(AT_FDCWD, name,
654 O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
655 MAY_EXEC | MAY_OPEN);
656 if (IS_ERR(file))
657 goto out;
659 err = -EACCES;
660 if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
661 goto exit;
663 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
664 goto exit;
666 fsnotify_open(file->f_path.dentry);
668 err = deny_write_access(file);
669 if (err)
670 goto exit;
672 out:
673 return file;
675 exit:
676 fput(file);
677 return ERR_PTR(err);
679 EXPORT_SYMBOL(open_exec);
681 int kernel_read(struct file *file, loff_t offset,
682 char *addr, unsigned long count)
684 mm_segment_t old_fs;
685 loff_t pos = offset;
686 int result;
688 old_fs = get_fs();
689 set_fs(get_ds());
690 /* The cast to a user pointer is valid due to the set_fs() */
691 result = vfs_read(file, (void __user *)addr, count, &pos);
692 set_fs(old_fs);
693 return result;
696 EXPORT_SYMBOL(kernel_read);
698 static int exec_mmap(struct mm_struct *mm)
700 struct task_struct *tsk;
701 struct mm_struct * old_mm, *active_mm;
703 /* Notify parent that we're no longer interested in the old VM */
704 tsk = current;
705 old_mm = current->mm;
706 mm_release(tsk, old_mm);
708 if (old_mm) {
710 * Make sure that if there is a core dump in progress
711 * for the old mm, we get out and die instead of going
712 * through with the exec. We must hold mmap_sem around
713 * checking core_state and changing tsk->mm.
715 down_read(&old_mm->mmap_sem);
716 if (unlikely(old_mm->core_state)) {
717 up_read(&old_mm->mmap_sem);
718 return -EINTR;
721 task_lock(tsk);
722 active_mm = tsk->active_mm;
723 tsk->mm = mm;
724 tsk->active_mm = mm;
725 activate_mm(active_mm, mm);
726 task_unlock(tsk);
727 arch_pick_mmap_layout(mm);
728 if (old_mm) {
729 up_read(&old_mm->mmap_sem);
730 BUG_ON(active_mm != old_mm);
731 mm_update_next_owner(old_mm);
732 mmput(old_mm);
733 return 0;
735 mmdrop(active_mm);
736 return 0;
740 * This function makes sure the current process has its own signal table,
741 * so that flush_signal_handlers can later reset the handlers without
742 * disturbing other processes. (Other processes might share the signal
743 * table via the CLONE_SIGHAND option to clone().)
745 static int de_thread(struct task_struct *tsk)
747 struct signal_struct *sig = tsk->signal;
748 struct sighand_struct *oldsighand = tsk->sighand;
749 spinlock_t *lock = &oldsighand->siglock;
750 int count;
752 if (thread_group_empty(tsk))
753 goto no_thread_group;
756 * Kill all other threads in the thread group.
758 spin_lock_irq(lock);
759 if (signal_group_exit(sig)) {
761 * Another group action in progress, just
762 * return so that the signal is processed.
764 spin_unlock_irq(lock);
765 return -EAGAIN;
767 sig->group_exit_task = tsk;
768 zap_other_threads(tsk);
770 /* Account for the thread group leader hanging around: */
771 count = thread_group_leader(tsk) ? 1 : 2;
772 sig->notify_count = count;
773 while (atomic_read(&sig->count) > count) {
774 __set_current_state(TASK_UNINTERRUPTIBLE);
775 spin_unlock_irq(lock);
776 schedule();
777 spin_lock_irq(lock);
779 spin_unlock_irq(lock);
782 * At this point all other threads have exited, all we have to
783 * do is to wait for the thread group leader to become inactive,
784 * and to assume its PID:
786 if (!thread_group_leader(tsk)) {
787 struct task_struct *leader = tsk->group_leader;
789 sig->notify_count = -1; /* for exit_notify() */
790 for (;;) {
791 write_lock_irq(&tasklist_lock);
792 if (likely(leader->exit_state))
793 break;
794 __set_current_state(TASK_UNINTERRUPTIBLE);
795 write_unlock_irq(&tasklist_lock);
796 schedule();
800 * The only record we have of the real-time age of a
801 * process, regardless of execs it's done, is start_time.
802 * All the past CPU time is accumulated in signal_struct
803 * from sister threads now dead. But in this non-leader
804 * exec, nothing survives from the original leader thread,
805 * whose birth marks the true age of this process now.
806 * When we take on its identity by switching to its PID, we
807 * also take its birthdate (always earlier than our own).
809 tsk->start_time = leader->start_time;
811 BUG_ON(!same_thread_group(leader, tsk));
812 BUG_ON(has_group_leader_pid(tsk));
814 * An exec() starts a new thread group with the
815 * TGID of the previous thread group. Rehash the
816 * two threads with a switched PID, and release
817 * the former thread group leader:
820 /* Become a process group leader with the old leader's pid.
821 * The old leader becomes a thread of the this thread group.
822 * Note: The old leader also uses this pid until release_task
823 * is called. Odd but simple and correct.
825 detach_pid(tsk, PIDTYPE_PID);
826 tsk->pid = leader->pid;
827 attach_pid(tsk, PIDTYPE_PID, task_pid(leader));
828 transfer_pid(leader, tsk, PIDTYPE_PGID);
829 transfer_pid(leader, tsk, PIDTYPE_SID);
830 list_replace_rcu(&leader->tasks, &tsk->tasks);
832 tsk->group_leader = tsk;
833 leader->group_leader = tsk;
835 tsk->exit_signal = SIGCHLD;
837 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
838 leader->exit_state = EXIT_DEAD;
839 write_unlock_irq(&tasklist_lock);
841 release_task(leader);
844 sig->group_exit_task = NULL;
845 sig->notify_count = 0;
847 no_thread_group:
848 exit_itimers(sig);
849 flush_itimer_signals();
851 if (atomic_read(&oldsighand->count) != 1) {
852 struct sighand_struct *newsighand;
854 * This ->sighand is shared with the CLONE_SIGHAND
855 * but not CLONE_THREAD task, switch to the new one.
857 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
858 if (!newsighand)
859 return -ENOMEM;
861 atomic_set(&newsighand->count, 1);
862 memcpy(newsighand->action, oldsighand->action,
863 sizeof(newsighand->action));
865 write_lock_irq(&tasklist_lock);
866 spin_lock(&oldsighand->siglock);
867 rcu_assign_pointer(tsk->sighand, newsighand);
868 spin_unlock(&oldsighand->siglock);
869 write_unlock_irq(&tasklist_lock);
871 __cleanup_sighand(oldsighand);
874 BUG_ON(!thread_group_leader(tsk));
875 return 0;
879 * These functions flushes out all traces of the currently running executable
880 * so that a new one can be started
882 static void flush_old_files(struct files_struct * files)
884 long j = -1;
885 struct fdtable *fdt;
887 spin_lock(&files->file_lock);
888 for (;;) {
889 unsigned long set, i;
891 j++;
892 i = j * __NFDBITS;
893 fdt = files_fdtable(files);
894 if (i >= fdt->max_fds)
895 break;
896 set = fdt->close_on_exec->fds_bits[j];
897 if (!set)
898 continue;
899 fdt->close_on_exec->fds_bits[j] = 0;
900 spin_unlock(&files->file_lock);
901 for ( ; set ; i++,set >>= 1) {
902 if (set & 1) {
903 sys_close(i);
906 spin_lock(&files->file_lock);
909 spin_unlock(&files->file_lock);
912 char *get_task_comm(char *buf, struct task_struct *tsk)
914 /* buf must be at least sizeof(tsk->comm) in size */
915 task_lock(tsk);
916 strncpy(buf, tsk->comm, sizeof(tsk->comm));
917 task_unlock(tsk);
918 return buf;
921 void set_task_comm(struct task_struct *tsk, char *buf)
923 task_lock(tsk);
924 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
925 task_unlock(tsk);
926 perf_counter_comm(tsk);
929 int flush_old_exec(struct linux_binprm * bprm)
931 char * name;
932 int i, ch, retval;
933 char tcomm[sizeof(current->comm)];
936 * Make sure we have a private signal table and that
937 * we are unassociated from the previous thread group.
939 retval = de_thread(current);
940 if (retval)
941 goto out;
943 set_mm_exe_file(bprm->mm, bprm->file);
946 * Release all of the old mmap stuff
948 retval = exec_mmap(bprm->mm);
949 if (retval)
950 goto out;
952 bprm->mm = NULL; /* We're using it now */
954 /* This is the point of no return */
955 current->sas_ss_sp = current->sas_ss_size = 0;
957 if (current_euid() == current_uid() && current_egid() == current_gid())
958 set_dumpable(current->mm, 1);
959 else
960 set_dumpable(current->mm, suid_dumpable);
962 name = bprm->filename;
964 /* Copies the binary name from after last slash */
965 for (i=0; (ch = *(name++)) != '\0';) {
966 if (ch == '/')
967 i = 0; /* overwrite what we wrote */
968 else
969 if (i < (sizeof(tcomm) - 1))
970 tcomm[i++] = ch;
972 tcomm[i] = '\0';
973 set_task_comm(current, tcomm);
975 current->flags &= ~PF_RANDOMIZE;
976 flush_thread();
978 /* Set the new mm task size. We have to do that late because it may
979 * depend on TIF_32BIT which is only updated in flush_thread() on
980 * some architectures like powerpc
982 current->mm->task_size = TASK_SIZE;
984 /* install the new credentials */
985 if (bprm->cred->uid != current_euid() ||
986 bprm->cred->gid != current_egid()) {
987 current->pdeath_signal = 0;
988 } else if (file_permission(bprm->file, MAY_READ) ||
989 bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
990 set_dumpable(current->mm, suid_dumpable);
993 current->personality &= ~bprm->per_clear;
996 * Flush performance counters when crossing a
997 * security domain:
999 if (!get_dumpable(current->mm))
1000 perf_counter_exit_task(current);
1002 /* An exec changes our domain. We are no longer part of the thread
1003 group */
1005 current->self_exec_id++;
1007 flush_signal_handlers(current, 0);
1008 flush_old_files(current->files);
1010 return 0;
1012 out:
1013 return retval;
1016 EXPORT_SYMBOL(flush_old_exec);
1019 * Prepare credentials and lock ->cred_guard_mutex.
1020 * install_exec_creds() commits the new creds and drops the lock.
1021 * Or, if exec fails before, free_bprm() should release ->cred and
1022 * and unlock.
1024 int prepare_bprm_creds(struct linux_binprm *bprm)
1026 if (mutex_lock_interruptible(&current->cred_guard_mutex))
1027 return -ERESTARTNOINTR;
1029 bprm->cred = prepare_exec_creds();
1030 if (likely(bprm->cred))
1031 return 0;
1033 mutex_unlock(&current->cred_guard_mutex);
1034 return -ENOMEM;
1037 void free_bprm(struct linux_binprm *bprm)
1039 free_arg_pages(bprm);
1040 if (bprm->cred) {
1041 mutex_unlock(&current->cred_guard_mutex);
1042 abort_creds(bprm->cred);
1044 kfree(bprm);
1048 * install the new credentials for this executable
1050 void install_exec_creds(struct linux_binprm *bprm)
1052 security_bprm_committing_creds(bprm);
1054 commit_creds(bprm->cred);
1055 bprm->cred = NULL;
1057 * cred_guard_mutex must be held at least to this point to prevent
1058 * ptrace_attach() from altering our determination of the task's
1059 * credentials; any time after this it may be unlocked.
1061 security_bprm_committed_creds(bprm);
1062 mutex_unlock(&current->cred_guard_mutex);
1064 EXPORT_SYMBOL(install_exec_creds);
1067 * determine how safe it is to execute the proposed program
1068 * - the caller must hold current->cred_guard_mutex to protect against
1069 * PTRACE_ATTACH
1071 int check_unsafe_exec(struct linux_binprm *bprm)
1073 struct task_struct *p = current, *t;
1074 unsigned n_fs;
1075 int res = 0;
1077 bprm->unsafe = tracehook_unsafe_exec(p);
1079 n_fs = 1;
1080 write_lock(&p->fs->lock);
1081 rcu_read_lock();
1082 for (t = next_thread(p); t != p; t = next_thread(t)) {
1083 if (t->fs == p->fs)
1084 n_fs++;
1086 rcu_read_unlock();
1088 if (p->fs->users > n_fs) {
1089 bprm->unsafe |= LSM_UNSAFE_SHARE;
1090 } else {
1091 res = -EAGAIN;
1092 if (!p->fs->in_exec) {
1093 p->fs->in_exec = 1;
1094 res = 1;
1097 write_unlock(&p->fs->lock);
1099 return res;
1103 * Fill the binprm structure from the inode.
1104 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1106 * This may be called multiple times for binary chains (scripts for example).
1108 int prepare_binprm(struct linux_binprm *bprm)
1110 umode_t mode;
1111 struct inode * inode = bprm->file->f_path.dentry->d_inode;
1112 int retval;
1114 mode = inode->i_mode;
1115 if (bprm->file->f_op == NULL)
1116 return -EACCES;
1118 /* clear any previous set[ug]id data from a previous binary */
1119 bprm->cred->euid = current_euid();
1120 bprm->cred->egid = current_egid();
1122 if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1123 /* Set-uid? */
1124 if (mode & S_ISUID) {
1125 bprm->per_clear |= PER_CLEAR_ON_SETID;
1126 bprm->cred->euid = inode->i_uid;
1129 /* Set-gid? */
1131 * If setgid is set but no group execute bit then this
1132 * is a candidate for mandatory locking, not a setgid
1133 * executable.
1135 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1136 bprm->per_clear |= PER_CLEAR_ON_SETID;
1137 bprm->cred->egid = inode->i_gid;
1141 /* fill in binprm security blob */
1142 retval = security_bprm_set_creds(bprm);
1143 if (retval)
1144 return retval;
1145 bprm->cred_prepared = 1;
1147 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1148 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1151 EXPORT_SYMBOL(prepare_binprm);
1154 * Arguments are '\0' separated strings found at the location bprm->p
1155 * points to; chop off the first by relocating brpm->p to right after
1156 * the first '\0' encountered.
1158 int remove_arg_zero(struct linux_binprm *bprm)
1160 int ret = 0;
1161 unsigned long offset;
1162 char *kaddr;
1163 struct page *page;
1165 if (!bprm->argc)
1166 return 0;
1168 do {
1169 offset = bprm->p & ~PAGE_MASK;
1170 page = get_arg_page(bprm, bprm->p, 0);
1171 if (!page) {
1172 ret = -EFAULT;
1173 goto out;
1175 kaddr = kmap_atomic(page, KM_USER0);
1177 for (; offset < PAGE_SIZE && kaddr[offset];
1178 offset++, bprm->p++)
1181 kunmap_atomic(kaddr, KM_USER0);
1182 put_arg_page(page);
1184 if (offset == PAGE_SIZE)
1185 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1186 } while (offset == PAGE_SIZE);
1188 bprm->p++;
1189 bprm->argc--;
1190 ret = 0;
1192 out:
1193 return ret;
1195 EXPORT_SYMBOL(remove_arg_zero);
1198 * cycle the list of binary formats handler, until one recognizes the image
1200 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1202 unsigned int depth = bprm->recursion_depth;
1203 int try,retval;
1204 struct linux_binfmt *fmt;
1206 retval = security_bprm_check(bprm);
1207 if (retval)
1208 return retval;
1209 retval = ima_bprm_check(bprm);
1210 if (retval)
1211 return retval;
1213 /* kernel module loader fixup */
1214 /* so we don't try to load run modprobe in kernel space. */
1215 set_fs(USER_DS);
1217 retval = audit_bprm(bprm);
1218 if (retval)
1219 return retval;
1221 retval = -ENOENT;
1222 for (try=0; try<2; try++) {
1223 read_lock(&binfmt_lock);
1224 list_for_each_entry(fmt, &formats, lh) {
1225 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1226 if (!fn)
1227 continue;
1228 if (!try_module_get(fmt->module))
1229 continue;
1230 read_unlock(&binfmt_lock);
1231 retval = fn(bprm, regs);
1233 * Restore the depth counter to its starting value
1234 * in this call, so we don't have to rely on every
1235 * load_binary function to restore it on return.
1237 bprm->recursion_depth = depth;
1238 if (retval >= 0) {
1239 if (depth == 0)
1240 tracehook_report_exec(fmt, bprm, regs);
1241 put_binfmt(fmt);
1242 allow_write_access(bprm->file);
1243 if (bprm->file)
1244 fput(bprm->file);
1245 bprm->file = NULL;
1246 current->did_exec = 1;
1247 proc_exec_connector(current);
1248 return retval;
1250 read_lock(&binfmt_lock);
1251 put_binfmt(fmt);
1252 if (retval != -ENOEXEC || bprm->mm == NULL)
1253 break;
1254 if (!bprm->file) {
1255 read_unlock(&binfmt_lock);
1256 return retval;
1259 read_unlock(&binfmt_lock);
1260 if (retval != -ENOEXEC || bprm->mm == NULL) {
1261 break;
1262 #ifdef CONFIG_MODULES
1263 } else {
1264 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1265 if (printable(bprm->buf[0]) &&
1266 printable(bprm->buf[1]) &&
1267 printable(bprm->buf[2]) &&
1268 printable(bprm->buf[3]))
1269 break; /* -ENOEXEC */
1270 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1271 #endif
1274 return retval;
1277 EXPORT_SYMBOL(search_binary_handler);
1280 * sys_execve() executes a new program.
1282 int do_execve(char * filename,
1283 char __user *__user *argv,
1284 char __user *__user *envp,
1285 struct pt_regs * regs)
1287 struct linux_binprm *bprm;
1288 struct file *file;
1289 struct files_struct *displaced;
1290 bool clear_in_exec;
1291 int retval;
1293 retval = unshare_files(&displaced);
1294 if (retval)
1295 goto out_ret;
1297 retval = -ENOMEM;
1298 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1299 if (!bprm)
1300 goto out_files;
1302 retval = prepare_bprm_creds(bprm);
1303 if (retval)
1304 goto out_free;
1306 retval = check_unsafe_exec(bprm);
1307 if (retval < 0)
1308 goto out_free;
1309 clear_in_exec = retval;
1310 current->in_execve = 1;
1312 file = open_exec(filename);
1313 retval = PTR_ERR(file);
1314 if (IS_ERR(file))
1315 goto out_unmark;
1317 sched_exec();
1319 bprm->file = file;
1320 bprm->filename = filename;
1321 bprm->interp = filename;
1323 retval = bprm_mm_init(bprm);
1324 if (retval)
1325 goto out_file;
1327 bprm->argc = count(argv, MAX_ARG_STRINGS);
1328 if ((retval = bprm->argc) < 0)
1329 goto out;
1331 bprm->envc = count(envp, MAX_ARG_STRINGS);
1332 if ((retval = bprm->envc) < 0)
1333 goto out;
1335 retval = prepare_binprm(bprm);
1336 if (retval < 0)
1337 goto out;
1339 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1340 if (retval < 0)
1341 goto out;
1343 bprm->exec = bprm->p;
1344 retval = copy_strings(bprm->envc, envp, bprm);
1345 if (retval < 0)
1346 goto out;
1348 retval = copy_strings(bprm->argc, argv, bprm);
1349 if (retval < 0)
1350 goto out;
1352 current->flags &= ~PF_KTHREAD;
1353 retval = search_binary_handler(bprm,regs);
1354 if (retval < 0)
1355 goto out;
1357 /* execve succeeded */
1358 current->fs->in_exec = 0;
1359 current->in_execve = 0;
1360 acct_update_integrals(current);
1361 free_bprm(bprm);
1362 if (displaced)
1363 put_files_struct(displaced);
1364 return retval;
1366 out:
1367 if (bprm->mm)
1368 mmput (bprm->mm);
1370 out_file:
1371 if (bprm->file) {
1372 allow_write_access(bprm->file);
1373 fput(bprm->file);
1376 out_unmark:
1377 if (clear_in_exec)
1378 current->fs->in_exec = 0;
1379 current->in_execve = 0;
1381 out_free:
1382 free_bprm(bprm);
1384 out_files:
1385 if (displaced)
1386 reset_files_struct(displaced);
1387 out_ret:
1388 return retval;
1391 int set_binfmt(struct linux_binfmt *new)
1393 struct linux_binfmt *old = current->binfmt;
1395 if (new) {
1396 if (!try_module_get(new->module))
1397 return -1;
1399 current->binfmt = new;
1400 if (old)
1401 module_put(old->module);
1402 return 0;
1405 EXPORT_SYMBOL(set_binfmt);
1407 /* format_corename will inspect the pattern parameter, and output a
1408 * name into corename, which must have space for at least
1409 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1411 static int format_corename(char *corename, long signr)
1413 const struct cred *cred = current_cred();
1414 const char *pat_ptr = core_pattern;
1415 int ispipe = (*pat_ptr == '|');
1416 char *out_ptr = corename;
1417 char *const out_end = corename + CORENAME_MAX_SIZE;
1418 int rc;
1419 int pid_in_pattern = 0;
1421 /* Repeat as long as we have more pattern to process and more output
1422 space */
1423 while (*pat_ptr) {
1424 if (*pat_ptr != '%') {
1425 if (out_ptr == out_end)
1426 goto out;
1427 *out_ptr++ = *pat_ptr++;
1428 } else {
1429 switch (*++pat_ptr) {
1430 case 0:
1431 goto out;
1432 /* Double percent, output one percent */
1433 case '%':
1434 if (out_ptr == out_end)
1435 goto out;
1436 *out_ptr++ = '%';
1437 break;
1438 /* pid */
1439 case 'p':
1440 pid_in_pattern = 1;
1441 rc = snprintf(out_ptr, out_end - out_ptr,
1442 "%d", task_tgid_vnr(current));
1443 if (rc > out_end - out_ptr)
1444 goto out;
1445 out_ptr += rc;
1446 break;
1447 /* uid */
1448 case 'u':
1449 rc = snprintf(out_ptr, out_end - out_ptr,
1450 "%d", cred->uid);
1451 if (rc > out_end - out_ptr)
1452 goto out;
1453 out_ptr += rc;
1454 break;
1455 /* gid */
1456 case 'g':
1457 rc = snprintf(out_ptr, out_end - out_ptr,
1458 "%d", cred->gid);
1459 if (rc > out_end - out_ptr)
1460 goto out;
1461 out_ptr += rc;
1462 break;
1463 /* signal that caused the coredump */
1464 case 's':
1465 rc = snprintf(out_ptr, out_end - out_ptr,
1466 "%ld", signr);
1467 if (rc > out_end - out_ptr)
1468 goto out;
1469 out_ptr += rc;
1470 break;
1471 /* UNIX time of coredump */
1472 case 't': {
1473 struct timeval tv;
1474 do_gettimeofday(&tv);
1475 rc = snprintf(out_ptr, out_end - out_ptr,
1476 "%lu", tv.tv_sec);
1477 if (rc > out_end - out_ptr)
1478 goto out;
1479 out_ptr += rc;
1480 break;
1482 /* hostname */
1483 case 'h':
1484 down_read(&uts_sem);
1485 rc = snprintf(out_ptr, out_end - out_ptr,
1486 "%s", utsname()->nodename);
1487 up_read(&uts_sem);
1488 if (rc > out_end - out_ptr)
1489 goto out;
1490 out_ptr += rc;
1491 break;
1492 /* executable */
1493 case 'e':
1494 rc = snprintf(out_ptr, out_end - out_ptr,
1495 "%s", current->comm);
1496 if (rc > out_end - out_ptr)
1497 goto out;
1498 out_ptr += rc;
1499 break;
1500 /* core limit size */
1501 case 'c':
1502 rc = snprintf(out_ptr, out_end - out_ptr,
1503 "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1504 if (rc > out_end - out_ptr)
1505 goto out;
1506 out_ptr += rc;
1507 break;
1508 default:
1509 break;
1511 ++pat_ptr;
1514 /* Backward compatibility with core_uses_pid:
1516 * If core_pattern does not include a %p (as is the default)
1517 * and core_uses_pid is set, then .%pid will be appended to
1518 * the filename. Do not do this for piped commands. */
1519 if (!ispipe && !pid_in_pattern && core_uses_pid) {
1520 rc = snprintf(out_ptr, out_end - out_ptr,
1521 ".%d", task_tgid_vnr(current));
1522 if (rc > out_end - out_ptr)
1523 goto out;
1524 out_ptr += rc;
1526 out:
1527 *out_ptr = 0;
1528 return ispipe;
1531 static int zap_process(struct task_struct *start)
1533 struct task_struct *t;
1534 int nr = 0;
1536 start->signal->flags = SIGNAL_GROUP_EXIT;
1537 start->signal->group_stop_count = 0;
1539 t = start;
1540 do {
1541 if (t != current && t->mm) {
1542 sigaddset(&t->pending.signal, SIGKILL);
1543 signal_wake_up(t, 1);
1544 nr++;
1546 } while_each_thread(start, t);
1548 return nr;
1551 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1552 struct core_state *core_state, int exit_code)
1554 struct task_struct *g, *p;
1555 unsigned long flags;
1556 int nr = -EAGAIN;
1558 spin_lock_irq(&tsk->sighand->siglock);
1559 if (!signal_group_exit(tsk->signal)) {
1560 mm->core_state = core_state;
1561 tsk->signal->group_exit_code = exit_code;
1562 nr = zap_process(tsk);
1564 spin_unlock_irq(&tsk->sighand->siglock);
1565 if (unlikely(nr < 0))
1566 return nr;
1568 if (atomic_read(&mm->mm_users) == nr + 1)
1569 goto done;
1571 * We should find and kill all tasks which use this mm, and we should
1572 * count them correctly into ->nr_threads. We don't take tasklist
1573 * lock, but this is safe wrt:
1575 * fork:
1576 * None of sub-threads can fork after zap_process(leader). All
1577 * processes which were created before this point should be
1578 * visible to zap_threads() because copy_process() adds the new
1579 * process to the tail of init_task.tasks list, and lock/unlock
1580 * of ->siglock provides a memory barrier.
1582 * do_exit:
1583 * The caller holds mm->mmap_sem. This means that the task which
1584 * uses this mm can't pass exit_mm(), so it can't exit or clear
1585 * its ->mm.
1587 * de_thread:
1588 * It does list_replace_rcu(&leader->tasks, &current->tasks),
1589 * we must see either old or new leader, this does not matter.
1590 * However, it can change p->sighand, so lock_task_sighand(p)
1591 * must be used. Since p->mm != NULL and we hold ->mmap_sem
1592 * it can't fail.
1594 * Note also that "g" can be the old leader with ->mm == NULL
1595 * and already unhashed and thus removed from ->thread_group.
1596 * This is OK, __unhash_process()->list_del_rcu() does not
1597 * clear the ->next pointer, we will find the new leader via
1598 * next_thread().
1600 rcu_read_lock();
1601 for_each_process(g) {
1602 if (g == tsk->group_leader)
1603 continue;
1604 if (g->flags & PF_KTHREAD)
1605 continue;
1606 p = g;
1607 do {
1608 if (p->mm) {
1609 if (unlikely(p->mm == mm)) {
1610 lock_task_sighand(p, &flags);
1611 nr += zap_process(p);
1612 unlock_task_sighand(p, &flags);
1614 break;
1616 } while_each_thread(g, p);
1618 rcu_read_unlock();
1619 done:
1620 atomic_set(&core_state->nr_threads, nr);
1621 return nr;
1624 static int coredump_wait(int exit_code, struct core_state *core_state)
1626 struct task_struct *tsk = current;
1627 struct mm_struct *mm = tsk->mm;
1628 struct completion *vfork_done;
1629 int core_waiters;
1631 init_completion(&core_state->startup);
1632 core_state->dumper.task = tsk;
1633 core_state->dumper.next = NULL;
1634 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1635 up_write(&mm->mmap_sem);
1637 if (unlikely(core_waiters < 0))
1638 goto fail;
1641 * Make sure nobody is waiting for us to release the VM,
1642 * otherwise we can deadlock when we wait on each other
1644 vfork_done = tsk->vfork_done;
1645 if (vfork_done) {
1646 tsk->vfork_done = NULL;
1647 complete(vfork_done);
1650 if (core_waiters)
1651 wait_for_completion(&core_state->startup);
1652 fail:
1653 return core_waiters;
1656 static void coredump_finish(struct mm_struct *mm)
1658 struct core_thread *curr, *next;
1659 struct task_struct *task;
1661 next = mm->core_state->dumper.next;
1662 while ((curr = next) != NULL) {
1663 next = curr->next;
1664 task = curr->task;
1666 * see exit_mm(), curr->task must not see
1667 * ->task == NULL before we read ->next.
1669 smp_mb();
1670 curr->task = NULL;
1671 wake_up_process(task);
1674 mm->core_state = NULL;
1678 * set_dumpable converts traditional three-value dumpable to two flags and
1679 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1680 * these bits are not changed atomically. So get_dumpable can observe the
1681 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1682 * return either old dumpable or new one by paying attention to the order of
1683 * modifying the bits.
1685 * dumpable | mm->flags (binary)
1686 * old new | initial interim final
1687 * ---------+-----------------------
1688 * 0 1 | 00 01 01
1689 * 0 2 | 00 10(*) 11
1690 * 1 0 | 01 00 00
1691 * 1 2 | 01 11 11
1692 * 2 0 | 11 10(*) 00
1693 * 2 1 | 11 11 01
1695 * (*) get_dumpable regards interim value of 10 as 11.
1697 void set_dumpable(struct mm_struct *mm, int value)
1699 switch (value) {
1700 case 0:
1701 clear_bit(MMF_DUMPABLE, &mm->flags);
1702 smp_wmb();
1703 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1704 break;
1705 case 1:
1706 set_bit(MMF_DUMPABLE, &mm->flags);
1707 smp_wmb();
1708 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1709 break;
1710 case 2:
1711 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1712 smp_wmb();
1713 set_bit(MMF_DUMPABLE, &mm->flags);
1714 break;
1718 int get_dumpable(struct mm_struct *mm)
1720 int ret;
1722 ret = mm->flags & 0x3;
1723 return (ret >= 2) ? 2 : ret;
1726 void do_coredump(long signr, int exit_code, struct pt_regs *regs)
1728 struct core_state core_state;
1729 char corename[CORENAME_MAX_SIZE + 1];
1730 struct mm_struct *mm = current->mm;
1731 struct linux_binfmt * binfmt;
1732 struct inode * inode;
1733 struct file * file;
1734 const struct cred *old_cred;
1735 struct cred *cred;
1736 int retval = 0;
1737 int flag = 0;
1738 int ispipe = 0;
1739 unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1740 char **helper_argv = NULL;
1741 int helper_argc = 0;
1742 char *delimit;
1744 audit_core_dumps(signr);
1746 binfmt = current->binfmt;
1747 if (!binfmt || !binfmt->core_dump)
1748 goto fail;
1750 cred = prepare_creds();
1751 if (!cred) {
1752 retval = -ENOMEM;
1753 goto fail;
1756 down_write(&mm->mmap_sem);
1758 * If another thread got here first, or we are not dumpable, bail out.
1760 if (mm->core_state || !get_dumpable(mm)) {
1761 up_write(&mm->mmap_sem);
1762 put_cred(cred);
1763 goto fail;
1767 * We cannot trust fsuid as being the "true" uid of the
1768 * process nor do we know its entire history. We only know it
1769 * was tainted so we dump it as root in mode 2.
1771 if (get_dumpable(mm) == 2) { /* Setuid core dump mode */
1772 flag = O_EXCL; /* Stop rewrite attacks */
1773 cred->fsuid = 0; /* Dump root private */
1776 retval = coredump_wait(exit_code, &core_state);
1777 if (retval < 0) {
1778 put_cred(cred);
1779 goto fail;
1782 old_cred = override_creds(cred);
1785 * Clear any false indication of pending signals that might
1786 * be seen by the filesystem code called to write the core file.
1788 clear_thread_flag(TIF_SIGPENDING);
1791 * lock_kernel() because format_corename() is controlled by sysctl, which
1792 * uses lock_kernel()
1794 lock_kernel();
1795 ispipe = format_corename(corename, signr);
1796 unlock_kernel();
1798 * Don't bother to check the RLIMIT_CORE value if core_pattern points
1799 * to a pipe. Since we're not writing directly to the filesystem
1800 * RLIMIT_CORE doesn't really apply, as no actual core file will be
1801 * created unless the pipe reader choses to write out the core file
1802 * at which point file size limits and permissions will be imposed
1803 * as it does with any other process
1805 if ((!ispipe) && (core_limit < binfmt->min_coredump))
1806 goto fail_unlock;
1808 if (ispipe) {
1809 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1810 if (!helper_argv) {
1811 printk(KERN_WARNING "%s failed to allocate memory\n",
1812 __func__);
1813 goto fail_unlock;
1815 /* Terminate the string before the first option */
1816 delimit = strchr(corename, ' ');
1817 if (delimit)
1818 *delimit = '\0';
1819 delimit = strrchr(helper_argv[0], '/');
1820 if (delimit)
1821 delimit++;
1822 else
1823 delimit = helper_argv[0];
1824 if (!strcmp(delimit, current->comm)) {
1825 printk(KERN_NOTICE "Recursive core dump detected, "
1826 "aborting\n");
1827 goto fail_unlock;
1830 core_limit = RLIM_INFINITY;
1832 /* SIGPIPE can happen, but it's just never processed */
1833 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
1834 &file)) {
1835 printk(KERN_INFO "Core dump to %s pipe failed\n",
1836 corename);
1837 goto fail_unlock;
1839 } else
1840 file = filp_open(corename,
1841 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1842 0600);
1843 if (IS_ERR(file))
1844 goto fail_unlock;
1845 inode = file->f_path.dentry->d_inode;
1846 if (inode->i_nlink > 1)
1847 goto close_fail; /* multiple links - don't dump */
1848 if (!ispipe && d_unhashed(file->f_path.dentry))
1849 goto close_fail;
1851 /* AK: actually i see no reason to not allow this for named pipes etc.,
1852 but keep the previous behaviour for now. */
1853 if (!ispipe && !S_ISREG(inode->i_mode))
1854 goto close_fail;
1856 * Dont allow local users get cute and trick others to coredump
1857 * into their pre-created files:
1859 if (inode->i_uid != current_fsuid())
1860 goto close_fail;
1861 if (!file->f_op)
1862 goto close_fail;
1863 if (!file->f_op->write)
1864 goto close_fail;
1865 if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1866 goto close_fail;
1868 retval = binfmt->core_dump(signr, regs, file, core_limit);
1870 if (retval)
1871 current->signal->group_exit_code |= 0x80;
1872 close_fail:
1873 filp_close(file, NULL);
1874 fail_unlock:
1875 if (helper_argv)
1876 argv_free(helper_argv);
1878 revert_creds(old_cred);
1879 put_cred(cred);
1880 coredump_finish(mm);
1881 fail:
1882 return;