4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * #!-checking implemented by tytso.
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
25 #include <linux/slab.h>
26 #include <linux/file.h>
27 #include <linux/fdtable.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/highmem.h>
37 #include <linux/spinlock.h>
38 #include <linux/key.h>
39 #include <linux/personality.h>
40 #include <linux/binfmts.h>
41 #include <linux/utsname.h>
42 #include <linux/pid_namespace.h>
43 #include <linux/module.h>
44 #include <linux/namei.h>
45 #include <linux/proc_fs.h>
46 #include <linux/mount.h>
47 #include <linux/security.h>
48 #include <linux/ima.h>
49 #include <linux/syscalls.h>
50 #include <linux/tsacct_kern.h>
51 #include <linux/cn_proc.h>
52 #include <linux/audit.h>
53 #include <linux/tracehook.h>
54 #include <linux/kmod.h>
55 #include <linux/fsnotify.h>
56 #include <linux/fs_struct.h>
58 #include <asm/uaccess.h>
59 #include <asm/mmu_context.h>
64 char core_pattern[CORENAME_MAX_SIZE] = "core";
65 int suid_dumpable = 0;
67 /* The maximal length of core_pattern is also specified in sysctl.c */
69 static LIST_HEAD(formats);
70 static DEFINE_RWLOCK(binfmt_lock);
72 int __register_binfmt(struct linux_binfmt * fmt, int insert)
76 write_lock(&binfmt_lock);
77 insert ? list_add(&fmt->lh, &formats) :
78 list_add_tail(&fmt->lh, &formats);
79 write_unlock(&binfmt_lock);
83 EXPORT_SYMBOL(__register_binfmt);
85 void unregister_binfmt(struct linux_binfmt * fmt)
87 write_lock(&binfmt_lock);
89 write_unlock(&binfmt_lock);
92 EXPORT_SYMBOL(unregister_binfmt);
94 static inline void put_binfmt(struct linux_binfmt * fmt)
96 module_put(fmt->module);
100 * Note that a shared library must be both readable and executable due to
103 * Also note that we take the address to load from from the file itself.
105 SYSCALL_DEFINE1(uselib, const char __user *, library)
109 char *tmp = getname(library);
110 int error = PTR_ERR(tmp);
113 error = path_lookup_open(AT_FDCWD, tmp,
115 FMODE_READ|FMODE_EXEC);
122 if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
126 if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
129 error = inode_permission(nd.path.dentry->d_inode,
130 MAY_READ | MAY_EXEC | MAY_OPEN);
133 error = ima_path_check(&nd.path, MAY_READ | MAY_EXEC | MAY_OPEN,
138 file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
139 error = PTR_ERR(file);
143 fsnotify_open(file->f_path.dentry);
147 struct linux_binfmt * fmt;
149 read_lock(&binfmt_lock);
150 list_for_each_entry(fmt, &formats, lh) {
151 if (!fmt->load_shlib)
153 if (!try_module_get(fmt->module))
155 read_unlock(&binfmt_lock);
156 error = fmt->load_shlib(file);
157 read_lock(&binfmt_lock);
159 if (error != -ENOEXEC)
162 read_unlock(&binfmt_lock);
168 release_open_intent(&nd);
175 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
181 #ifdef CONFIG_STACK_GROWSUP
183 ret = expand_stack_downwards(bprm->vma, pos);
188 ret = get_user_pages(current, bprm->mm, pos,
189 1, write, 1, &page, NULL);
194 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
198 * We've historically supported up to 32 pages (ARG_MAX)
199 * of argument strings even with small stacks
205 * Limit to 1/4-th the stack size for the argv+env strings.
207 * - the remaining binfmt code will not run out of stack space,
208 * - the program will have a reasonable amount of stack left
211 rlim = current->signal->rlim;
212 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
221 static void put_arg_page(struct page *page)
226 static void free_arg_page(struct linux_binprm *bprm, int i)
230 static void free_arg_pages(struct linux_binprm *bprm)
234 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
237 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
240 static int __bprm_mm_init(struct linux_binprm *bprm)
243 struct vm_area_struct *vma = NULL;
244 struct mm_struct *mm = bprm->mm;
246 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
250 down_write(&mm->mmap_sem);
254 * Place the stack at the largest stack address the architecture
255 * supports. Later, we'll move this to an appropriate place. We don't
256 * use STACK_TOP because that can depend on attributes which aren't
259 vma->vm_end = STACK_TOP_MAX;
260 vma->vm_start = vma->vm_end - PAGE_SIZE;
261 vma->vm_flags = VM_STACK_FLAGS;
262 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
263 err = insert_vm_struct(mm, vma);
267 mm->stack_vm = mm->total_vm = 1;
268 up_write(&mm->mmap_sem);
269 bprm->p = vma->vm_end - sizeof(void *);
272 up_write(&mm->mmap_sem);
274 kmem_cache_free(vm_area_cachep, vma);
278 static bool valid_arg_len(struct linux_binprm *bprm, long len)
280 return len <= MAX_ARG_STRLEN;
285 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
290 page = bprm->page[pos / PAGE_SIZE];
291 if (!page && write) {
292 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
295 bprm->page[pos / PAGE_SIZE] = page;
301 static void put_arg_page(struct page *page)
305 static void free_arg_page(struct linux_binprm *bprm, int i)
308 __free_page(bprm->page[i]);
309 bprm->page[i] = NULL;
313 static void free_arg_pages(struct linux_binprm *bprm)
317 for (i = 0; i < MAX_ARG_PAGES; i++)
318 free_arg_page(bprm, i);
321 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
326 static int __bprm_mm_init(struct linux_binprm *bprm)
328 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
332 static bool valid_arg_len(struct linux_binprm *bprm, long len)
334 return len <= bprm->p;
337 #endif /* CONFIG_MMU */
340 * Create a new mm_struct and populate it with a temporary stack
341 * vm_area_struct. We don't have enough context at this point to set the stack
342 * flags, permissions, and offset, so we use temporary values. We'll update
343 * them later in setup_arg_pages().
345 int bprm_mm_init(struct linux_binprm *bprm)
348 struct mm_struct *mm = NULL;
350 bprm->mm = mm = mm_alloc();
355 err = init_new_context(current, mm);
359 err = __bprm_mm_init(bprm);
375 * count() counts the number of strings in array ARGV.
377 static int count(char __user * __user * argv, int max)
385 if (get_user(p, argv))
399 * 'copy_strings()' copies argument/environment strings from the old
400 * processes's memory to the new process's stack. The call to get_user_pages()
401 * ensures the destination page is created and not swapped out.
403 static int copy_strings(int argc, char __user * __user * argv,
404 struct linux_binprm *bprm)
406 struct page *kmapped_page = NULL;
408 unsigned long kpos = 0;
416 if (get_user(str, argv+argc) ||
417 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
422 if (!valid_arg_len(bprm, len)) {
427 /* We're going to work our way backwords. */
433 int offset, bytes_to_copy;
435 offset = pos % PAGE_SIZE;
439 bytes_to_copy = offset;
440 if (bytes_to_copy > len)
443 offset -= bytes_to_copy;
444 pos -= bytes_to_copy;
445 str -= bytes_to_copy;
446 len -= bytes_to_copy;
448 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
451 page = get_arg_page(bprm, pos, 1);
458 flush_kernel_dcache_page(kmapped_page);
459 kunmap(kmapped_page);
460 put_arg_page(kmapped_page);
463 kaddr = kmap(kmapped_page);
464 kpos = pos & PAGE_MASK;
465 flush_arg_page(bprm, kpos, kmapped_page);
467 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
476 flush_kernel_dcache_page(kmapped_page);
477 kunmap(kmapped_page);
478 put_arg_page(kmapped_page);
484 * Like copy_strings, but get argv and its values from kernel memory.
486 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
489 mm_segment_t oldfs = get_fs();
491 r = copy_strings(argc, (char __user * __user *)argv, bprm);
495 EXPORT_SYMBOL(copy_strings_kernel);
500 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
501 * the binfmt code determines where the new stack should reside, we shift it to
502 * its final location. The process proceeds as follows:
504 * 1) Use shift to calculate the new vma endpoints.
505 * 2) Extend vma to cover both the old and new ranges. This ensures the
506 * arguments passed to subsequent functions are consistent.
507 * 3) Move vma's page tables to the new range.
508 * 4) Free up any cleared pgd range.
509 * 5) Shrink the vma to cover only the new range.
511 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
513 struct mm_struct *mm = vma->vm_mm;
514 unsigned long old_start = vma->vm_start;
515 unsigned long old_end = vma->vm_end;
516 unsigned long length = old_end - old_start;
517 unsigned long new_start = old_start - shift;
518 unsigned long new_end = old_end - shift;
519 struct mmu_gather *tlb;
521 BUG_ON(new_start > new_end);
524 * ensure there are no vmas between where we want to go
527 if (vma != find_vma(mm, new_start))
531 * cover the whole range: [new_start, old_end)
533 vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
536 * move the page tables downwards, on failure we rely on
537 * process cleanup to remove whatever mess we made.
539 if (length != move_page_tables(vma, old_start,
540 vma, new_start, length))
544 tlb = tlb_gather_mmu(mm, 0);
545 if (new_end > old_start) {
547 * when the old and new regions overlap clear from new_end.
549 free_pgd_range(tlb, new_end, old_end, new_end,
550 vma->vm_next ? vma->vm_next->vm_start : 0);
553 * otherwise, clean from old_start; this is done to not touch
554 * the address space in [new_end, old_start) some architectures
555 * have constraints on va-space that make this illegal (IA64) -
556 * for the others its just a little faster.
558 free_pgd_range(tlb, old_start, old_end, new_end,
559 vma->vm_next ? vma->vm_next->vm_start : 0);
561 tlb_finish_mmu(tlb, new_end, old_end);
564 * shrink the vma to just the new range.
566 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
571 #define EXTRA_STACK_VM_PAGES 20 /* random */
574 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
575 * the stack is optionally relocated, and some extra space is added.
577 int setup_arg_pages(struct linux_binprm *bprm,
578 unsigned long stack_top,
579 int executable_stack)
582 unsigned long stack_shift;
583 struct mm_struct *mm = current->mm;
584 struct vm_area_struct *vma = bprm->vma;
585 struct vm_area_struct *prev = NULL;
586 unsigned long vm_flags;
587 unsigned long stack_base;
589 #ifdef CONFIG_STACK_GROWSUP
590 /* Limit stack size to 1GB */
591 stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
592 if (stack_base > (1 << 30))
593 stack_base = 1 << 30;
595 /* Make sure we didn't let the argument array grow too large. */
596 if (vma->vm_end - vma->vm_start > stack_base)
599 stack_base = PAGE_ALIGN(stack_top - stack_base);
601 stack_shift = vma->vm_start - stack_base;
602 mm->arg_start = bprm->p - stack_shift;
603 bprm->p = vma->vm_end - stack_shift;
605 stack_top = arch_align_stack(stack_top);
606 stack_top = PAGE_ALIGN(stack_top);
607 stack_shift = vma->vm_end - stack_top;
609 bprm->p -= stack_shift;
610 mm->arg_start = bprm->p;
614 bprm->loader -= stack_shift;
615 bprm->exec -= stack_shift;
617 down_write(&mm->mmap_sem);
618 vm_flags = VM_STACK_FLAGS;
621 * Adjust stack execute permissions; explicitly enable for
622 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
623 * (arch default) otherwise.
625 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
627 else if (executable_stack == EXSTACK_DISABLE_X)
628 vm_flags &= ~VM_EXEC;
629 vm_flags |= mm->def_flags;
631 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
637 /* Move stack pages down in memory. */
639 ret = shift_arg_pages(vma, stack_shift);
641 up_write(&mm->mmap_sem);
646 #ifdef CONFIG_STACK_GROWSUP
647 stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
649 stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
651 ret = expand_stack(vma, stack_base);
656 up_write(&mm->mmap_sem);
659 EXPORT_SYMBOL(setup_arg_pages);
661 #endif /* CONFIG_MMU */
663 struct file *open_exec(const char *name)
669 err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd,
670 FMODE_READ|FMODE_EXEC);
675 if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
678 if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
681 err = inode_permission(nd.path.dentry->d_inode, MAY_EXEC | MAY_OPEN);
684 err = ima_path_check(&nd.path, MAY_EXEC | MAY_OPEN, IMA_COUNT_UPDATE);
688 file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
692 fsnotify_open(file->f_path.dentry);
694 err = deny_write_access(file);
703 release_open_intent(&nd);
708 EXPORT_SYMBOL(open_exec);
710 int kernel_read(struct file *file, unsigned long offset,
711 char *addr, unsigned long count)
719 /* The cast to a user pointer is valid due to the set_fs() */
720 result = vfs_read(file, (void __user *)addr, count, &pos);
725 EXPORT_SYMBOL(kernel_read);
727 static int exec_mmap(struct mm_struct *mm)
729 struct task_struct *tsk;
730 struct mm_struct * old_mm, *active_mm;
732 /* Notify parent that we're no longer interested in the old VM */
734 old_mm = current->mm;
735 mm_release(tsk, old_mm);
739 * Make sure that if there is a core dump in progress
740 * for the old mm, we get out and die instead of going
741 * through with the exec. We must hold mmap_sem around
742 * checking core_state and changing tsk->mm.
744 down_read(&old_mm->mmap_sem);
745 if (unlikely(old_mm->core_state)) {
746 up_read(&old_mm->mmap_sem);
751 active_mm = tsk->active_mm;
754 activate_mm(active_mm, mm);
756 arch_pick_mmap_layout(mm);
758 up_read(&old_mm->mmap_sem);
759 BUG_ON(active_mm != old_mm);
760 mm_update_next_owner(old_mm);
769 * This function makes sure the current process has its own signal table,
770 * so that flush_signal_handlers can later reset the handlers without
771 * disturbing other processes. (Other processes might share the signal
772 * table via the CLONE_SIGHAND option to clone().)
774 static int de_thread(struct task_struct *tsk)
776 struct signal_struct *sig = tsk->signal;
777 struct sighand_struct *oldsighand = tsk->sighand;
778 spinlock_t *lock = &oldsighand->siglock;
781 if (thread_group_empty(tsk))
782 goto no_thread_group;
785 * Kill all other threads in the thread group.
788 if (signal_group_exit(sig)) {
790 * Another group action in progress, just
791 * return so that the signal is processed.
793 spin_unlock_irq(lock);
796 sig->group_exit_task = tsk;
797 zap_other_threads(tsk);
799 /* Account for the thread group leader hanging around: */
800 count = thread_group_leader(tsk) ? 1 : 2;
801 sig->notify_count = count;
802 while (atomic_read(&sig->count) > count) {
803 __set_current_state(TASK_UNINTERRUPTIBLE);
804 spin_unlock_irq(lock);
808 spin_unlock_irq(lock);
811 * At this point all other threads have exited, all we have to
812 * do is to wait for the thread group leader to become inactive,
813 * and to assume its PID:
815 if (!thread_group_leader(tsk)) {
816 struct task_struct *leader = tsk->group_leader;
818 sig->notify_count = -1; /* for exit_notify() */
820 write_lock_irq(&tasklist_lock);
821 if (likely(leader->exit_state))
823 __set_current_state(TASK_UNINTERRUPTIBLE);
824 write_unlock_irq(&tasklist_lock);
829 * The only record we have of the real-time age of a
830 * process, regardless of execs it's done, is start_time.
831 * All the past CPU time is accumulated in signal_struct
832 * from sister threads now dead. But in this non-leader
833 * exec, nothing survives from the original leader thread,
834 * whose birth marks the true age of this process now.
835 * When we take on its identity by switching to its PID, we
836 * also take its birthdate (always earlier than our own).
838 tsk->start_time = leader->start_time;
840 BUG_ON(!same_thread_group(leader, tsk));
841 BUG_ON(has_group_leader_pid(tsk));
843 * An exec() starts a new thread group with the
844 * TGID of the previous thread group. Rehash the
845 * two threads with a switched PID, and release
846 * the former thread group leader:
849 /* Become a process group leader with the old leader's pid.
850 * The old leader becomes a thread of the this thread group.
851 * Note: The old leader also uses this pid until release_task
852 * is called. Odd but simple and correct.
854 detach_pid(tsk, PIDTYPE_PID);
855 tsk->pid = leader->pid;
856 attach_pid(tsk, PIDTYPE_PID, task_pid(leader));
857 transfer_pid(leader, tsk, PIDTYPE_PGID);
858 transfer_pid(leader, tsk, PIDTYPE_SID);
859 list_replace_rcu(&leader->tasks, &tsk->tasks);
861 tsk->group_leader = tsk;
862 leader->group_leader = tsk;
864 tsk->exit_signal = SIGCHLD;
866 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
867 leader->exit_state = EXIT_DEAD;
868 write_unlock_irq(&tasklist_lock);
870 release_task(leader);
873 sig->group_exit_task = NULL;
874 sig->notify_count = 0;
878 flush_itimer_signals();
880 if (atomic_read(&oldsighand->count) != 1) {
881 struct sighand_struct *newsighand;
883 * This ->sighand is shared with the CLONE_SIGHAND
884 * but not CLONE_THREAD task, switch to the new one.
886 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
890 atomic_set(&newsighand->count, 1);
891 memcpy(newsighand->action, oldsighand->action,
892 sizeof(newsighand->action));
894 write_lock_irq(&tasklist_lock);
895 spin_lock(&oldsighand->siglock);
896 rcu_assign_pointer(tsk->sighand, newsighand);
897 spin_unlock(&oldsighand->siglock);
898 write_unlock_irq(&tasklist_lock);
900 __cleanup_sighand(oldsighand);
903 BUG_ON(!thread_group_leader(tsk));
908 * These functions flushes out all traces of the currently running executable
909 * so that a new one can be started
911 static void flush_old_files(struct files_struct * files)
916 spin_lock(&files->file_lock);
918 unsigned long set, i;
922 fdt = files_fdtable(files);
923 if (i >= fdt->max_fds)
925 set = fdt->close_on_exec->fds_bits[j];
928 fdt->close_on_exec->fds_bits[j] = 0;
929 spin_unlock(&files->file_lock);
930 for ( ; set ; i++,set >>= 1) {
935 spin_lock(&files->file_lock);
938 spin_unlock(&files->file_lock);
941 char *get_task_comm(char *buf, struct task_struct *tsk)
943 /* buf must be at least sizeof(tsk->comm) in size */
945 strncpy(buf, tsk->comm, sizeof(tsk->comm));
950 void set_task_comm(struct task_struct *tsk, char *buf)
953 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
957 int flush_old_exec(struct linux_binprm * bprm)
961 char tcomm[sizeof(current->comm)];
964 * Make sure we have a private signal table and that
965 * we are unassociated from the previous thread group.
967 retval = de_thread(current);
971 set_mm_exe_file(bprm->mm, bprm->file);
974 * Release all of the old mmap stuff
976 retval = exec_mmap(bprm->mm);
980 bprm->mm = NULL; /* We're using it now */
982 /* This is the point of no return */
983 current->sas_ss_sp = current->sas_ss_size = 0;
985 if (current_euid() == current_uid() && current_egid() == current_gid())
986 set_dumpable(current->mm, 1);
988 set_dumpable(current->mm, suid_dumpable);
990 name = bprm->filename;
992 /* Copies the binary name from after last slash */
993 for (i=0; (ch = *(name++)) != '\0';) {
995 i = 0; /* overwrite what we wrote */
997 if (i < (sizeof(tcomm) - 1))
1001 set_task_comm(current, tcomm);
1003 current->flags &= ~PF_RANDOMIZE;
1006 /* Set the new mm task size. We have to do that late because it may
1007 * depend on TIF_32BIT which is only updated in flush_thread() on
1008 * some architectures like powerpc
1010 current->mm->task_size = TASK_SIZE;
1012 /* install the new credentials */
1013 if (bprm->cred->uid != current_euid() ||
1014 bprm->cred->gid != current_egid()) {
1015 current->pdeath_signal = 0;
1016 } else if (file_permission(bprm->file, MAY_READ) ||
1017 bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
1018 set_dumpable(current->mm, suid_dumpable);
1021 current->personality &= ~bprm->per_clear;
1023 /* An exec changes our domain. We are no longer part of the thread
1026 current->self_exec_id++;
1028 flush_signal_handlers(current, 0);
1029 flush_old_files(current->files);
1037 EXPORT_SYMBOL(flush_old_exec);
1040 * install the new credentials for this executable
1042 void install_exec_creds(struct linux_binprm *bprm)
1044 security_bprm_committing_creds(bprm);
1046 commit_creds(bprm->cred);
1049 /* cred_guard_mutex must be held at least to this point to prevent
1050 * ptrace_attach() from altering our determination of the task's
1051 * credentials; any time after this it may be unlocked */
1053 security_bprm_committed_creds(bprm);
1055 EXPORT_SYMBOL(install_exec_creds);
1058 * determine how safe it is to execute the proposed program
1059 * - the caller must hold current->cred_guard_mutex to protect against
1062 int check_unsafe_exec(struct linux_binprm *bprm)
1064 struct task_struct *p = current, *t;
1068 bprm->unsafe = tracehook_unsafe_exec(p);
1071 write_lock(&p->fs->lock);
1073 for (t = next_thread(p); t != p; t = next_thread(t)) {
1079 if (p->fs->users > n_fs) {
1080 bprm->unsafe |= LSM_UNSAFE_SHARE;
1083 if (!p->fs->in_exec) {
1088 write_unlock(&p->fs->lock);
1094 * Fill the binprm structure from the inode.
1095 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1097 * This may be called multiple times for binary chains (scripts for example).
1099 int prepare_binprm(struct linux_binprm *bprm)
1102 struct inode * inode = bprm->file->f_path.dentry->d_inode;
1105 mode = inode->i_mode;
1106 if (bprm->file->f_op == NULL)
1109 /* clear any previous set[ug]id data from a previous binary */
1110 bprm->cred->euid = current_euid();
1111 bprm->cred->egid = current_egid();
1113 if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1115 if (mode & S_ISUID) {
1116 bprm->per_clear |= PER_CLEAR_ON_SETID;
1117 bprm->cred->euid = inode->i_uid;
1122 * If setgid is set but no group execute bit then this
1123 * is a candidate for mandatory locking, not a setgid
1126 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1127 bprm->per_clear |= PER_CLEAR_ON_SETID;
1128 bprm->cred->egid = inode->i_gid;
1132 /* fill in binprm security blob */
1133 retval = security_bprm_set_creds(bprm);
1136 bprm->cred_prepared = 1;
1138 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1139 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1142 EXPORT_SYMBOL(prepare_binprm);
1145 * Arguments are '\0' separated strings found at the location bprm->p
1146 * points to; chop off the first by relocating brpm->p to right after
1147 * the first '\0' encountered.
1149 int remove_arg_zero(struct linux_binprm *bprm)
1152 unsigned long offset;
1160 offset = bprm->p & ~PAGE_MASK;
1161 page = get_arg_page(bprm, bprm->p, 0);
1166 kaddr = kmap_atomic(page, KM_USER0);
1168 for (; offset < PAGE_SIZE && kaddr[offset];
1169 offset++, bprm->p++)
1172 kunmap_atomic(kaddr, KM_USER0);
1175 if (offset == PAGE_SIZE)
1176 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1177 } while (offset == PAGE_SIZE);
1186 EXPORT_SYMBOL(remove_arg_zero);
1189 * cycle the list of binary formats handler, until one recognizes the image
1191 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1193 unsigned int depth = bprm->recursion_depth;
1195 struct linux_binfmt *fmt;
1197 retval = security_bprm_check(bprm);
1200 retval = ima_bprm_check(bprm);
1204 /* kernel module loader fixup */
1205 /* so we don't try to load run modprobe in kernel space. */
1208 retval = audit_bprm(bprm);
1213 for (try=0; try<2; try++) {
1214 read_lock(&binfmt_lock);
1215 list_for_each_entry(fmt, &formats, lh) {
1216 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1219 if (!try_module_get(fmt->module))
1221 read_unlock(&binfmt_lock);
1222 retval = fn(bprm, regs);
1224 * Restore the depth counter to its starting value
1225 * in this call, so we don't have to rely on every
1226 * load_binary function to restore it on return.
1228 bprm->recursion_depth = depth;
1231 tracehook_report_exec(fmt, bprm, regs);
1233 allow_write_access(bprm->file);
1237 current->did_exec = 1;
1238 proc_exec_connector(current);
1241 read_lock(&binfmt_lock);
1243 if (retval != -ENOEXEC || bprm->mm == NULL)
1246 read_unlock(&binfmt_lock);
1250 read_unlock(&binfmt_lock);
1251 if (retval != -ENOEXEC || bprm->mm == NULL) {
1253 #ifdef CONFIG_MODULES
1255 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1256 if (printable(bprm->buf[0]) &&
1257 printable(bprm->buf[1]) &&
1258 printable(bprm->buf[2]) &&
1259 printable(bprm->buf[3]))
1260 break; /* -ENOEXEC */
1261 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1268 EXPORT_SYMBOL(search_binary_handler);
1270 void free_bprm(struct linux_binprm *bprm)
1272 free_arg_pages(bprm);
1274 abort_creds(bprm->cred);
1279 * sys_execve() executes a new program.
1281 int do_execve(char * filename,
1282 char __user *__user *argv,
1283 char __user *__user *envp,
1284 struct pt_regs * regs)
1286 struct linux_binprm *bprm;
1288 struct files_struct *displaced;
1292 retval = unshare_files(&displaced);
1297 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1301 retval = mutex_lock_interruptible(¤t->cred_guard_mutex);
1304 current->in_execve = 1;
1307 bprm->cred = prepare_exec_creds();
1311 retval = check_unsafe_exec(bprm);
1314 clear_in_exec = retval;
1316 file = open_exec(filename);
1317 retval = PTR_ERR(file);
1324 bprm->filename = filename;
1325 bprm->interp = filename;
1327 retval = bprm_mm_init(bprm);
1331 bprm->argc = count(argv, MAX_ARG_STRINGS);
1332 if ((retval = bprm->argc) < 0)
1335 bprm->envc = count(envp, MAX_ARG_STRINGS);
1336 if ((retval = bprm->envc) < 0)
1339 retval = prepare_binprm(bprm);
1343 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1347 bprm->exec = bprm->p;
1348 retval = copy_strings(bprm->envc, envp, bprm);
1352 retval = copy_strings(bprm->argc, argv, bprm);
1356 current->flags &= ~PF_KTHREAD;
1357 retval = search_binary_handler(bprm,regs);
1361 /* execve succeeded */
1362 current->fs->in_exec = 0;
1363 current->in_execve = 0;
1364 mutex_unlock(¤t->cred_guard_mutex);
1365 acct_update_integrals(current);
1368 put_files_struct(displaced);
1377 allow_write_access(bprm->file);
1383 current->fs->in_exec = 0;
1386 current->in_execve = 0;
1387 mutex_unlock(¤t->cred_guard_mutex);
1394 reset_files_struct(displaced);
1399 int set_binfmt(struct linux_binfmt *new)
1401 struct linux_binfmt *old = current->binfmt;
1404 if (!try_module_get(new->module))
1407 current->binfmt = new;
1409 module_put(old->module);
1413 EXPORT_SYMBOL(set_binfmt);
1415 /* format_corename will inspect the pattern parameter, and output a
1416 * name into corename, which must have space for at least
1417 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1419 static int format_corename(char *corename, long signr)
1421 const struct cred *cred = current_cred();
1422 const char *pat_ptr = core_pattern;
1423 int ispipe = (*pat_ptr == '|');
1424 char *out_ptr = corename;
1425 char *const out_end = corename + CORENAME_MAX_SIZE;
1427 int pid_in_pattern = 0;
1429 /* Repeat as long as we have more pattern to process and more output
1432 if (*pat_ptr != '%') {
1433 if (out_ptr == out_end)
1435 *out_ptr++ = *pat_ptr++;
1437 switch (*++pat_ptr) {
1440 /* Double percent, output one percent */
1442 if (out_ptr == out_end)
1449 rc = snprintf(out_ptr, out_end - out_ptr,
1450 "%d", task_tgid_vnr(current));
1451 if (rc > out_end - out_ptr)
1457 rc = snprintf(out_ptr, out_end - out_ptr,
1459 if (rc > out_end - out_ptr)
1465 rc = snprintf(out_ptr, out_end - out_ptr,
1467 if (rc > out_end - out_ptr)
1471 /* signal that caused the coredump */
1473 rc = snprintf(out_ptr, out_end - out_ptr,
1475 if (rc > out_end - out_ptr)
1479 /* UNIX time of coredump */
1482 do_gettimeofday(&tv);
1483 rc = snprintf(out_ptr, out_end - out_ptr,
1485 if (rc > out_end - out_ptr)
1492 down_read(&uts_sem);
1493 rc = snprintf(out_ptr, out_end - out_ptr,
1494 "%s", utsname()->nodename);
1496 if (rc > out_end - out_ptr)
1502 rc = snprintf(out_ptr, out_end - out_ptr,
1503 "%s", current->comm);
1504 if (rc > out_end - out_ptr)
1508 /* core limit size */
1510 rc = snprintf(out_ptr, out_end - out_ptr,
1511 "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1512 if (rc > out_end - out_ptr)
1522 /* Backward compatibility with core_uses_pid:
1524 * If core_pattern does not include a %p (as is the default)
1525 * and core_uses_pid is set, then .%pid will be appended to
1526 * the filename. Do not do this for piped commands. */
1527 if (!ispipe && !pid_in_pattern && core_uses_pid) {
1528 rc = snprintf(out_ptr, out_end - out_ptr,
1529 ".%d", task_tgid_vnr(current));
1530 if (rc > out_end - out_ptr)
1539 static int zap_process(struct task_struct *start)
1541 struct task_struct *t;
1544 start->signal->flags = SIGNAL_GROUP_EXIT;
1545 start->signal->group_stop_count = 0;
1549 if (t != current && t->mm) {
1550 sigaddset(&t->pending.signal, SIGKILL);
1551 signal_wake_up(t, 1);
1554 } while_each_thread(start, t);
1559 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1560 struct core_state *core_state, int exit_code)
1562 struct task_struct *g, *p;
1563 unsigned long flags;
1566 spin_lock_irq(&tsk->sighand->siglock);
1567 if (!signal_group_exit(tsk->signal)) {
1568 mm->core_state = core_state;
1569 tsk->signal->group_exit_code = exit_code;
1570 nr = zap_process(tsk);
1572 spin_unlock_irq(&tsk->sighand->siglock);
1573 if (unlikely(nr < 0))
1576 if (atomic_read(&mm->mm_users) == nr + 1)
1579 * We should find and kill all tasks which use this mm, and we should
1580 * count them correctly into ->nr_threads. We don't take tasklist
1581 * lock, but this is safe wrt:
1584 * None of sub-threads can fork after zap_process(leader). All
1585 * processes which were created before this point should be
1586 * visible to zap_threads() because copy_process() adds the new
1587 * process to the tail of init_task.tasks list, and lock/unlock
1588 * of ->siglock provides a memory barrier.
1591 * The caller holds mm->mmap_sem. This means that the task which
1592 * uses this mm can't pass exit_mm(), so it can't exit or clear
1596 * It does list_replace_rcu(&leader->tasks, ¤t->tasks),
1597 * we must see either old or new leader, this does not matter.
1598 * However, it can change p->sighand, so lock_task_sighand(p)
1599 * must be used. Since p->mm != NULL and we hold ->mmap_sem
1602 * Note also that "g" can be the old leader with ->mm == NULL
1603 * and already unhashed and thus removed from ->thread_group.
1604 * This is OK, __unhash_process()->list_del_rcu() does not
1605 * clear the ->next pointer, we will find the new leader via
1609 for_each_process(g) {
1610 if (g == tsk->group_leader)
1612 if (g->flags & PF_KTHREAD)
1617 if (unlikely(p->mm == mm)) {
1618 lock_task_sighand(p, &flags);
1619 nr += zap_process(p);
1620 unlock_task_sighand(p, &flags);
1624 } while_each_thread(g, p);
1628 atomic_set(&core_state->nr_threads, nr);
1632 static int coredump_wait(int exit_code, struct core_state *core_state)
1634 struct task_struct *tsk = current;
1635 struct mm_struct *mm = tsk->mm;
1636 struct completion *vfork_done;
1639 init_completion(&core_state->startup);
1640 core_state->dumper.task = tsk;
1641 core_state->dumper.next = NULL;
1642 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1643 up_write(&mm->mmap_sem);
1645 if (unlikely(core_waiters < 0))
1649 * Make sure nobody is waiting for us to release the VM,
1650 * otherwise we can deadlock when we wait on each other
1652 vfork_done = tsk->vfork_done;
1654 tsk->vfork_done = NULL;
1655 complete(vfork_done);
1659 wait_for_completion(&core_state->startup);
1661 return core_waiters;
1664 static void coredump_finish(struct mm_struct *mm)
1666 struct core_thread *curr, *next;
1667 struct task_struct *task;
1669 next = mm->core_state->dumper.next;
1670 while ((curr = next) != NULL) {
1674 * see exit_mm(), curr->task must not see
1675 * ->task == NULL before we read ->next.
1679 wake_up_process(task);
1682 mm->core_state = NULL;
1686 * set_dumpable converts traditional three-value dumpable to two flags and
1687 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1688 * these bits are not changed atomically. So get_dumpable can observe the
1689 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1690 * return either old dumpable or new one by paying attention to the order of
1691 * modifying the bits.
1693 * dumpable | mm->flags (binary)
1694 * old new | initial interim final
1695 * ---------+-----------------------
1703 * (*) get_dumpable regards interim value of 10 as 11.
1705 void set_dumpable(struct mm_struct *mm, int value)
1709 clear_bit(MMF_DUMPABLE, &mm->flags);
1711 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1714 set_bit(MMF_DUMPABLE, &mm->flags);
1716 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1719 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1721 set_bit(MMF_DUMPABLE, &mm->flags);
1726 int get_dumpable(struct mm_struct *mm)
1730 ret = mm->flags & 0x3;
1731 return (ret >= 2) ? 2 : ret;
1734 void do_coredump(long signr, int exit_code, struct pt_regs *regs)
1736 struct core_state core_state;
1737 char corename[CORENAME_MAX_SIZE + 1];
1738 struct mm_struct *mm = current->mm;
1739 struct linux_binfmt * binfmt;
1740 struct inode * inode;
1742 const struct cred *old_cred;
1747 unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1748 char **helper_argv = NULL;
1749 int helper_argc = 0;
1752 audit_core_dumps(signr);
1754 binfmt = current->binfmt;
1755 if (!binfmt || !binfmt->core_dump)
1758 cred = prepare_creds();
1764 down_write(&mm->mmap_sem);
1766 * If another thread got here first, or we are not dumpable, bail out.
1768 if (mm->core_state || !get_dumpable(mm)) {
1769 up_write(&mm->mmap_sem);
1775 * We cannot trust fsuid as being the "true" uid of the
1776 * process nor do we know its entire history. We only know it
1777 * was tainted so we dump it as root in mode 2.
1779 if (get_dumpable(mm) == 2) { /* Setuid core dump mode */
1780 flag = O_EXCL; /* Stop rewrite attacks */
1781 cred->fsuid = 0; /* Dump root private */
1784 retval = coredump_wait(exit_code, &core_state);
1790 old_cred = override_creds(cred);
1793 * Clear any false indication of pending signals that might
1794 * be seen by the filesystem code called to write the core file.
1796 clear_thread_flag(TIF_SIGPENDING);
1799 * lock_kernel() because format_corename() is controlled by sysctl, which
1800 * uses lock_kernel()
1803 ispipe = format_corename(corename, signr);
1806 * Don't bother to check the RLIMIT_CORE value if core_pattern points
1807 * to a pipe. Since we're not writing directly to the filesystem
1808 * RLIMIT_CORE doesn't really apply, as no actual core file will be
1809 * created unless the pipe reader choses to write out the core file
1810 * at which point file size limits and permissions will be imposed
1811 * as it does with any other process
1813 if ((!ispipe) && (core_limit < binfmt->min_coredump))
1817 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1819 printk(KERN_WARNING "%s failed to allocate memory\n",
1823 /* Terminate the string before the first option */
1824 delimit = strchr(corename, ' ');
1827 delimit = strrchr(helper_argv[0], '/');
1831 delimit = helper_argv[0];
1832 if (!strcmp(delimit, current->comm)) {
1833 printk(KERN_NOTICE "Recursive core dump detected, "
1838 core_limit = RLIM_INFINITY;
1840 /* SIGPIPE can happen, but it's just never processed */
1841 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
1843 printk(KERN_INFO "Core dump to %s pipe failed\n",
1848 file = filp_open(corename,
1849 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1853 inode = file->f_path.dentry->d_inode;
1854 if (inode->i_nlink > 1)
1855 goto close_fail; /* multiple links - don't dump */
1856 if (!ispipe && d_unhashed(file->f_path.dentry))
1859 /* AK: actually i see no reason to not allow this for named pipes etc.,
1860 but keep the previous behaviour for now. */
1861 if (!ispipe && !S_ISREG(inode->i_mode))
1864 * Dont allow local users get cute and trick others to coredump
1865 * into their pre-created files:
1867 if (inode->i_uid != current_fsuid())
1871 if (!file->f_op->write)
1873 if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1876 retval = binfmt->core_dump(signr, regs, file, core_limit);
1879 current->signal->group_exit_code |= 0x80;
1881 filp_close(file, NULL);
1884 argv_free(helper_argv);
1886 revert_creds(old_cred);
1888 coredump_finish(mm);