diff options
Diffstat (limited to 'fs/exec.c')
| -rw-r--r-- | fs/exec.c | 1498 |
1 files changed, 1498 insertions, 0 deletions
diff --git a/fs/exec.c b/fs/exec.c new file mode 100644 index 000000000000..a8394499926c --- /dev/null +++ b/fs/exec.c @@ -0,0 +1,1498 @@ +/* + * linux/fs/exec.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + */ + +/* + * #!-checking implemented by tytso. + */ +/* + * Demand-loading implemented 01.12.91 - no need to read anything but + * the header into memory. The inode of the executable is put into + * "current->executable", and page faults do the actual loading. Clean. + * + * Once more I can proudly say that linux stood up to being changed: it + * was less than 2 hours work to get demand-loading completely implemented. + * + * Demand loading changed July 1993 by Eric Youngdale. Use mmap instead, + * current->executable is only used by the procfs. This allows a dispatch + * table to check for several different types of binary formats. We keep + * trying until we recognize the file or we run out of supported binary + * formats. + */ + +#include <linux/config.h> +#include <linux/slab.h> +#include <linux/file.h> +#include <linux/mman.h> +#include <linux/a.out.h> +#include <linux/stat.h> +#include <linux/fcntl.h> +#include <linux/smp_lock.h> +#include <linux/init.h> +#include <linux/pagemap.h> +#include <linux/highmem.h> +#include <linux/spinlock.h> +#include <linux/key.h> +#include <linux/personality.h> +#include <linux/binfmts.h> +#include <linux/swap.h> +#include <linux/utsname.h> +#include <linux/module.h> +#include <linux/namei.h> +#include <linux/proc_fs.h> +#include <linux/ptrace.h> +#include <linux/mount.h> +#include <linux/security.h> +#include <linux/syscalls.h> +#include <linux/rmap.h> +#include <linux/acct.h> + +#include <asm/uaccess.h> +#include <asm/mmu_context.h> + +#ifdef CONFIG_KMOD +#include <linux/kmod.h> +#endif + +int core_uses_pid; +char core_pattern[65] = "core"; +/* The maximal length of core_pattern is also specified in sysctl.c */ + +static struct linux_binfmt *formats; +static DEFINE_RWLOCK(binfmt_lock); + +int register_binfmt(struct linux_binfmt * fmt) +{ + struct linux_binfmt ** tmp = &formats; + + if (!fmt) + return -EINVAL; + if (fmt->next) + return -EBUSY; + write_lock(&binfmt_lock); + while (*tmp) { + if (fmt == *tmp) { + write_unlock(&binfmt_lock); + return -EBUSY; + } + tmp = &(*tmp)->next; + } + fmt->next = formats; + formats = fmt; + write_unlock(&binfmt_lock); + return 0; +} + +EXPORT_SYMBOL(register_binfmt); + +int unregister_binfmt(struct linux_binfmt * fmt) +{ + struct linux_binfmt ** tmp = &formats; + + write_lock(&binfmt_lock); + while (*tmp) { + if (fmt == *tmp) { + *tmp = fmt->next; + write_unlock(&binfmt_lock); + return 0; + } + tmp = &(*tmp)->next; + } + write_unlock(&binfmt_lock); + return -EINVAL; +} + +EXPORT_SYMBOL(unregister_binfmt); + +static inline void put_binfmt(struct linux_binfmt * fmt) +{ + module_put(fmt->module); +} + +/* + * Note that a shared library must be both readable and executable due to + * security reasons. + * + * Also note that we take the address to load from from the file itself. + */ +asmlinkage long sys_uselib(const char __user * library) +{ + struct file * file; + struct nameidata nd; + int error; + + nd.intent.open.flags = FMODE_READ; + error = __user_walk(library, LOOKUP_FOLLOW|LOOKUP_OPEN, &nd); + if (error) + goto out; + + error = -EINVAL; + if (!S_ISREG(nd.dentry->d_inode->i_mode)) + goto exit; + + error = permission(nd.dentry->d_inode, MAY_READ | MAY_EXEC, &nd); + if (error) + goto exit; + + file = dentry_open(nd.dentry, nd.mnt, O_RDONLY); + error = PTR_ERR(file); + if (IS_ERR(file)) + goto out; + + error = -ENOEXEC; + if(file->f_op) { + struct linux_binfmt * fmt; + + read_lock(&binfmt_lock); + for (fmt = formats ; fmt ; fmt = fmt->next) { + if (!fmt->load_shlib) + continue; + if (!try_module_get(fmt->module)) + continue; + read_unlock(&binfmt_lock); + error = fmt->load_shlib(file); + read_lock(&binfmt_lock); + put_binfmt(fmt); + if (error != -ENOEXEC) + break; + } + read_unlock(&binfmt_lock); + } + fput(file); +out: + return error; +exit: + path_release(&nd); + goto out; +} + +/* + * count() counts the number of strings in array ARGV. + */ +static int count(char __user * __user * argv, int max) +{ + int i = 0; + + if (argv != NULL) { + for (;;) { + char __user * p; + + if (get_user(p, argv)) + return -EFAULT; + if (!p) + break; + argv++; + if(++i > max) + return -E2BIG; + cond_resched(); + } + } + return i; +} + +/* + * 'copy_strings()' copies argument/environment strings from user + * memory to free pages in kernel mem. These are in a format ready + * to be put directly into the top of new user memory. + */ +int copy_strings(int argc,char __user * __user * argv, struct linux_binprm *bprm) +{ + struct page *kmapped_page = NULL; + char *kaddr = NULL; + int ret; + + while (argc-- > 0) { + char __user *str; + int len; + unsigned long pos; + + if (get_user(str, argv+argc) || + !(len = strnlen_user(str, bprm->p))) { + ret = -EFAULT; + goto out; + } + + if (bprm->p < len) { + ret = -E2BIG; + goto out; + } + + bprm->p -= len; + /* XXX: add architecture specific overflow check here. */ + pos = bprm->p; + + while (len > 0) { + int i, new, err; + int offset, bytes_to_copy; + struct page *page; + + offset = pos % PAGE_SIZE; + i = pos/PAGE_SIZE; + page = bprm->page[i]; + new = 0; + if (!page) { + page = alloc_page(GFP_HIGHUSER); + bprm->page[i] = page; + if (!page) { + ret = -ENOMEM; + goto out; + } + new = 1; + } + + if (page != kmapped_page) { + if (kmapped_page) + kunmap(kmapped_page); + kmapped_page = page; + kaddr = kmap(kmapped_page); + } + if (new && offset) + memset(kaddr, 0, offset); + bytes_to_copy = PAGE_SIZE - offset; + if (bytes_to_copy > len) { + bytes_to_copy = len; + if (new) + memset(kaddr+offset+len, 0, + PAGE_SIZE-offset-len); + } + err = copy_from_user(kaddr+offset, str, bytes_to_copy); + if (err) { + ret = -EFAULT; + goto out; + } + + pos += bytes_to_copy; + str += bytes_to_copy; + len -= bytes_to_copy; + } + } + ret = 0; +out: + if (kmapped_page) + kunmap(kmapped_page); + return ret; +} + +/* + * Like copy_strings, but get argv and its values from kernel memory. + */ +int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm) +{ + int r; + mm_segment_t oldfs = get_fs(); + set_fs(KERNEL_DS); + r = copy_strings(argc, (char __user * __user *)argv, bprm); + set_fs(oldfs); + return r; +} + +EXPORT_SYMBOL(copy_strings_kernel); + +#ifdef CONFIG_MMU +/* + * This routine is used to map in a page into an address space: needed by + * execve() for the initial stack and environment pages. + * + * vma->vm_mm->mmap_sem is held for writing. + */ +void install_arg_page(struct vm_area_struct *vma, + struct page *page, unsigned long address) +{ + struct mm_struct *mm = vma->vm_mm; + pgd_t * pgd; + pud_t * pud; + pmd_t * pmd; + pte_t * pte; + + if (unlikely(anon_vma_prepare(vma))) + goto out_sig; + + flush_dcache_page(page); + pgd = pgd_offset(mm, address); + + spin_lock(&mm->page_table_lock); + pud = pud_alloc(mm, pgd, address); + if (!pud) + goto out; + pmd = pmd_alloc(mm, pud, address); + if (!pmd) + goto out; + pte = pte_alloc_map(mm, pmd, address); + if (!pte) + goto out; + if (!pte_none(*pte)) { + pte_unmap(pte); + goto out; + } + inc_mm_counter(mm, rss); + lru_cache_add_active(page); + set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte( + page, vma->vm_page_prot)))); + page_add_anon_rmap(page, vma, address); + pte_unmap(pte); + spin_unlock(&mm->page_table_lock); + + /* no need for flush_tlb */ + return; +out: + spin_unlock(&mm->page_table_lock); +out_sig: + __free_page(page); + force_sig(SIGKILL, current); +} + +#define EXTRA_STACK_VM_PAGES 20 /* random */ + +int setup_arg_pages(struct linux_binprm *bprm, + unsigned long stack_top, + int executable_stack) +{ + unsigned long stack_base; + struct vm_area_struct *mpnt; + struct mm_struct *mm = current->mm; + int i, ret; + long arg_size; + +#ifdef CONFIG_STACK_GROWSUP + /* Move the argument and environment strings to the bottom of the + * stack space. + */ + int offset, j; + char *to, *from; + + /* Start by shifting all the pages down */ + i = 0; + for (j = 0; j < MAX_ARG_PAGES; j++) { + struct page *page = bprm->page[j]; + if (!page) + continue; + bprm->page[i++] = page; + } + + /* Now move them within their pages */ + offset = bprm->p % PAGE_SIZE; + to = kmap(bprm->page[0]); + for (j = 1; j < i; j++) { + memmove(to, to + offset, PAGE_SIZE - offset); + from = kmap(bprm->page[j]); + memcpy(to + PAGE_SIZE - offset, from, offset); + kunmap(bprm->page[j - 1]); + to = from; + } + memmove(to, to + offset, PAGE_SIZE - offset); + kunmap(bprm->page[j - 1]); + + /* Limit stack size to 1GB */ + stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max; + if (stack_base > (1 << 30)) + stack_base = 1 << 30; + stack_base = PAGE_ALIGN(stack_top - stack_base); + + /* Adjust bprm->p to point to the end of the strings. */ + bprm->p = stack_base + PAGE_SIZE * i - offset; + + mm->arg_start = stack_base; + arg_size = i << PAGE_SHIFT; + + /* zero pages that were copied above */ + while (i < MAX_ARG_PAGES) + bprm->page[i++] = NULL; +#else + stack_base = arch_align_stack(stack_top - MAX_ARG_PAGES*PAGE_SIZE); + stack_base = PAGE_ALIGN(stack_base); + bprm->p += stack_base; + mm->arg_start = bprm->p; + arg_size = stack_top - (PAGE_MASK & (unsigned long) mm->arg_start); +#endif + + arg_size += EXTRA_STACK_VM_PAGES * PAGE_SIZE; + + if (bprm->loader) + bprm->loader += stack_base; + bprm->exec += stack_base; + + mpnt = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); + if (!mpnt) + return -ENOMEM; + + if (security_vm_enough_memory(arg_size >> PAGE_SHIFT)) { + kmem_cache_free(vm_area_cachep, mpnt); + return -ENOMEM; + } + + memset(mpnt, 0, sizeof(*mpnt)); + + down_write(&mm->mmap_sem); + { + mpnt->vm_mm = mm; +#ifdef CONFIG_STACK_GROWSUP + mpnt->vm_start = stack_base; + mpnt->vm_end = stack_base + arg_size; +#else + mpnt->vm_end = stack_top; + mpnt->vm_start = mpnt->vm_end - arg_size; +#endif + /* Adjust stack execute permissions; explicitly enable + * for EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X + * and leave alone (arch default) otherwise. */ + if (unlikely(executable_stack == EXSTACK_ENABLE_X)) + mpnt->vm_flags = VM_STACK_FLAGS | VM_EXEC; + else if (executable_stack == EXSTACK_DISABLE_X) + mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC; + else + mpnt->vm_flags = VM_STACK_FLAGS; + mpnt->vm_flags |= mm->def_flags; + mpnt->vm_page_prot = protection_map[mpnt->vm_flags & 0x7]; + if ((ret = insert_vm_struct(mm, mpnt))) { + up_write(&mm->mmap_sem); + kmem_cache_free(vm_area_cachep, mpnt); + return ret; + } + mm->stack_vm = mm->total_vm = vma_pages(mpnt); + } + + for (i = 0 ; i < MAX_ARG_PAGES ; i++) { + struct page *page = bprm->page[i]; + if (page) { + bprm->page[i] = NULL; + install_arg_page(mpnt, page, stack_base); + } + stack_base += PAGE_SIZE; + } + up_write(&mm->mmap_sem); + + return 0; +} + +EXPORT_SYMBOL(setup_arg_pages); + +#define free_arg_pages(bprm) do { } while (0) + +#else + +static inline void free_arg_pages(struct linux_binprm *bprm) +{ + int i; + + for (i = 0; i < MAX_ARG_PAGES; i++) { + if (bprm->page[i]) + __free_page(bprm->page[i]); + bprm->page[i] = NULL; + } +} + +#endif /* CONFIG_MMU */ + +struct file *open_exec(const char *name) +{ + struct nameidata nd; + int err; + struct file *file; + + nd.intent.open.flags = FMODE_READ; + err = path_lookup(name, LOOKUP_FOLLOW|LOOKUP_OPEN, &nd); + file = ERR_PTR(err); + + if (!err) { + struct inode *inode = nd.dentry->d_inode; + file = ERR_PTR(-EACCES); + if (!(nd.mnt->mnt_flags & MNT_NOEXEC) && + S_ISREG(inode->i_mode)) { + int err = permission(inode, MAY_EXEC, &nd); + if (!err && !(inode->i_mode & 0111)) + err = -EACCES; + file = ERR_PTR(err); + if (!err) { + file = dentry_open(nd.dentry, nd.mnt, O_RDONLY); + if (!IS_ERR(file)) { + err = deny_write_access(file); + if (err) { + fput(file); + file = ERR_PTR(err); + } + } +out: + return file; + } + } + path_release(&nd); + } + goto out; +} + +EXPORT_SYMBOL(open_exec); + +int kernel_read(struct file *file, unsigned long offset, + char *addr, unsigned long count) +{ + mm_segment_t old_fs; + loff_t pos = offset; + int result; + + old_fs = get_fs(); + set_fs(get_ds()); + /* The cast to a user pointer is valid due to the set_fs() */ + result = vfs_read(file, (void __user *)addr, count, &pos); + set_fs(old_fs); + return result; +} + +EXPORT_SYMBOL(kernel_read); + +static int exec_mmap(struct mm_struct *mm) +{ + struct task_struct *tsk; + struct mm_struct * old_mm, *active_mm; + + /* Notify parent that we're no longer interested in the old VM */ + tsk = current; + old_mm = current->mm; + mm_release(tsk, old_mm); + + if (old_mm) { + /* + * Make sure that if there is a core dump in progress + * for the old mm, we get out and die instead of going + * through with the exec. We must hold mmap_sem around + * checking core_waiters and changing tsk->mm. The + * core-inducing thread will increment core_waiters for + * each thread whose ->mm == old_mm. + */ + down_read(&old_mm->mmap_sem); + if (unlikely(old_mm->core_waiters)) { + up_read(&old_mm->mmap_sem); + return -EINTR; + } + } + task_lock(tsk); + active_mm = tsk->active_mm; + tsk->mm = mm; + tsk->active_mm = mm; + activate_mm(active_mm, mm); + task_unlock(tsk); + arch_pick_mmap_layout(mm); + if (old_mm) { + up_read(&old_mm->mmap_sem); + if (active_mm != old_mm) BUG(); + mmput(old_mm); + return 0; + } + mmdrop(active_mm); + return 0; +} + +/* + * This function makes sure the current process has its own signal table, + * so that flush_signal_handlers can later reset the handlers without + * disturbing other processes. (Other processes might share the signal + * table via the CLONE_SIGHAND option to clone().) + */ +static inline int de_thread(struct task_struct *tsk) +{ + struct signal_struct *sig = tsk->signal; + struct sighand_struct *newsighand, *oldsighand = tsk->sighand; + spinlock_t *lock = &oldsighand->siglock; + int count; + + /* + * If we don't share sighandlers, then we aren't sharing anything + * and we can just re-use it all. + */ + if (atomic_read(&oldsighand->count) <= 1) { + BUG_ON(atomic_read(&sig->count) != 1); + exit_itimers(sig); + return 0; + } + + newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); + if (!newsighand) + return -ENOMEM; + + if (thread_group_empty(current)) + goto no_thread_group; + + /* + * Kill all other threads in the thread group. + * We must hold tasklist_lock to call zap_other_threads. + */ + read_lock(&tasklist_lock); + spin_lock_irq(lock); + if (sig->flags & SIGNAL_GROUP_EXIT) { + /* + * Another group action in progress, just + * return so that the signal is processed. + */ + spin_unlock_irq(lock); + read_unlock(&tasklist_lock); + kmem_cache_free(sighand_cachep, newsighand); + return -EAGAIN; + } + zap_other_threads(current); + read_unlock(&tasklist_lock); + + /* + * Account for the thread group leader hanging around: + */ + count = 2; + if (thread_group_leader(current)) + count = 1; + while (atomic_read(&sig->count) > count) { + sig->group_exit_task = current; + sig->notify_count = count; + __set_current_state(TASK_UNINTERRUPTIBLE); + spin_unlock_irq(lock); + schedule(); + spin_lock_irq(lock); + } + sig->group_exit_task = NULL; + sig->notify_count = 0; + spin_unlock_irq(lock); + + /* + * At this point all other threads have exited, all we have to + * do is to wait for the thread group leader to become inactive, + * and to assume its PID: + */ + if (!thread_group_leader(current)) { + struct task_struct *leader = current->group_leader, *parent; + struct dentry *proc_dentry1, *proc_dentry2; + unsigned long exit_state, ptrace; + + /* + * Wait for the thread group leader to be a zombie. + * It should already be zombie at this point, most + * of the time. + */ + while (leader->exit_state != EXIT_ZOMBIE) + yield(); + + spin_lock(&leader->proc_lock); + spin_lock(¤t->proc_lock); + proc_dentry1 = proc_pid_unhash(current); + proc_dentry2 = proc_pid_unhash(leader); + write_lock_irq(&tasklist_lock); + + if (leader->tgid != current->tgid) + BUG(); + if (current->pid == current->tgid) + BUG(); + /* + * An exec() starts a new thread group with the + * TGID of the previous thread group. Rehash the + * two threads with a switched PID, and release + * the former thread group leader: + */ + ptrace = leader->ptrace; + parent = leader->parent; + if (unlikely(ptrace) && unlikely(parent == current)) { + /* + * Joker was ptracing his own group leader, + * and now he wants to be his own parent! + * We can't have that. + */ + ptrace = 0; + } + + ptrace_unlink(current); + ptrace_unlink(leader); + remove_parent(current); + remove_parent(leader); + + switch_exec_pids(leader, current); + + current->parent = current->real_parent = leader->real_parent; + leader->parent = leader->real_parent = child_reaper; + current->group_leader = current; + leader->group_leader = leader; + + add_parent(current, current->parent); + add_parent(leader, leader->parent); + if (ptrace) { + current->ptrace = ptrace; + __ptrace_link(current, parent); + } + + list_del(¤t->tasks); + list_add_tail(¤t->tasks, &init_task.tasks); + current->exit_signal = SIGCHLD; + exit_state = leader->exit_state; + + write_unlock_irq(&tasklist_lock); + spin_unlock(&leader->proc_lock); + spin_unlock(¤t->proc_lock); + proc_pid_flush(proc_dentry1); + proc_pid_flush(proc_dentry2); + + if (exit_state != EXIT_ZOMBIE) + BUG(); + release_task(leader); + } + + /* + * Now there are really no other threads at all, + * so it's safe to stop telling them to kill themselves. + */ + sig->flags = 0; + +no_thread_group: + BUG_ON(atomic_read(&sig->count) != 1); + exit_itimers(sig); + + if (atomic_read(&oldsighand->count) == 1) { + /* + * Now that we nuked the rest of the thread group, + * it turns out we are not sharing sighand any more either. + * So we can just keep it. + */ + kmem_cache_free(sighand_cachep, newsighand); + } else { + /* + * Move our state over to newsighand and switch it in. + */ + spin_lock_init(&newsighand->siglock); + atomic_set(&newsighand->count, 1); + memcpy(newsighand->action, oldsighand->action, + sizeof(newsighand->action)); + + write_lock_irq(&tasklist_lock); + spin_lock(&oldsighand->siglock); + spin_lock(&newsighand->siglock); + + current->sighand = newsighand; + recalc_sigpending(); + + spin_unlock(&newsighand->siglock); + spin_unlock(&oldsighand->siglock); + write_unlock_irq(&tasklist_lock); + + if (atomic_dec_and_test(&oldsighand->count)) + kmem_cache_free(sighand_cachep, oldsighand); + } + + if (!thread_group_empty(current)) + BUG(); + if (!thread_group_leader(current)) + BUG(); + return 0; +} + +/* + * These functions flushes out all traces of the currently running executable + * so that a new one can be started + */ + +static inline void flush_old_files(struct files_struct * files) +{ + long j = -1; + + spin_lock(&files->file_lock); + for (;;) { + unsigned long set, i; + + j++; + i = j * __NFDBITS; + if (i >= files->max_fds || i >= files->max_fdset) + break; + set = files->close_on_exec->fds_bits[j]; + if (!set) + continue; + files->close_on_exec->fds_bits[j] = 0; + spin_unlock(&files->file_lock); + for ( ; set ; i++,set >>= 1) { + if (set & 1) { + sys_close(i); + } + } + spin_lock(&files->file_lock); + + } + spin_unlock(&files->file_lock); +} + +void get_task_comm(char *buf, struct task_struct *tsk) +{ + /* buf must be at least sizeof(tsk->comm) in size */ + task_lock(tsk); + strncpy(buf, tsk->comm, sizeof(tsk->comm)); + task_unlock(tsk); +} + +void set_task_comm(struct task_struct *tsk, char *buf) +{ + task_lock(tsk); + strlcpy(tsk->comm, buf, sizeof(tsk->comm)); + task_unlock(tsk); +} + +int flush_old_exec(struct linux_binprm * bprm) +{ + char * name; + int i, ch, retval; + struct files_struct *files; + char tcomm[sizeof(current->comm)]; + + /* + * Make sure we have a private signal table and that + * we are unassociated from the previous thread group. + */ + retval = de_thread(current); + if (retval) + goto out; + + /* + * Make sure we have private file handles. Ask the + * fork helper to do the work for us and the exit + * helper to do the cleanup of the old one. + */ + files = current->files; /* refcounted so safe to hold */ + retval = unshare_files(); + if (retval) + goto out; + /* + * Release all of the old mmap stuff + */ + retval = exec_mmap(bprm->mm); + if (retval) + goto mmap_failed; + + bprm->mm = NULL; /* We're using it now */ + + /* This is the point of no return */ + steal_locks(files); + put_files_struct(files); + + current->sas_ss_sp = current->sas_ss_size = 0; + + if (current->euid == current->uid && current->egid == current->gid) + current->mm->dumpable = 1; + name = bprm->filename; + for (i=0; (ch = *(name++)) != '\0';) { + if (ch == '/') + i = 0; + else + if (i < (sizeof(tcomm) - 1)) + tcomm[i++] = ch; + } + tcomm[i] = '\0'; + set_task_comm(current, tcomm); + + current->flags &= ~PF_RANDOMIZE; + flush_thread(); + + if (bprm->e_uid != current->euid || bprm->e_gid != current->egid || + permission(bprm->file->f_dentry->d_inode,MAY_READ, NULL) || + (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) { + suid_keys(current); + current->mm->dumpable = 0; + } + + /* An exec changes our domain. We are no longer part of the thread + group */ + + current->self_exec_id++; + + flush_signal_handlers(current, 0); + flush_old_files(current->files); + + return 0; + +mmap_failed: + put_files_struct(current->files); + current->files = files; +out: + return retval; +} + +EXPORT_SYMBOL(flush_old_exec); + +/* + * Fill the binprm structure from the inode. + * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes + */ +int prepare_binprm(struct linux_binprm *bprm) +{ + int mode; + struct inode * inode = bprm->file->f_dentry->d_inode; + int retval; + + mode = inode->i_mode; + /* + * Check execute perms again - if the caller has CAP_DAC_OVERRIDE, + * generic_permission lets a non-executable through + */ + if (!(mode & 0111)) /* with at least _one_ execute bit set */ + return -EACCES; + if (bprm->file->f_op == NULL) + return -EACCES; + + bprm->e_uid = current->euid; + bprm->e_gid = current->egid; + + if(!(bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)) { + /* Set-uid? */ + if (mode & S_ISUID) { + current->personality &= ~PER_CLEAR_ON_SETID; + bprm->e_uid = inode->i_uid; + } + + /* Set-gid? */ + /* + * If setgid is set but no group execute bit then this + * is a candidate for mandatory locking, not a setgid + * executable. + */ + if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { + current->personality &= ~PER_CLEAR_ON_SETID; + bprm->e_gid = inode->i_gid; + } + } + + /* fill in binprm security blob */ + retval = security_bprm_set(bprm); + if (retval) + return retval; + + memset(bprm->buf,0,BINPRM_BUF_SIZE); + return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE); +} + +EXPORT_SYMBOL(prepare_binprm); + +static inline int unsafe_exec(struct task_struct *p) +{ + int unsafe = 0; + if (p->ptrace & PT_PTRACED) { + if (p->ptrace & PT_PTRACE_CAP) + unsafe |= LSM_UNSAFE_PTRACE_CAP; + else + unsafe |= LSM_UNSAFE_PTRACE; + } + if (atomic_read(&p->fs->count) > 1 || + atomic_read(&p->files->count) > 1 || + atomic_read(&p->sighand->count) > 1) + unsafe |= LSM_UNSAFE_SHARE; + + return unsafe; +} + +void compute_creds(struct linux_binprm *bprm) +{ + int unsafe; + + if (bprm->e_uid != current->uid) + suid_keys(current); + exec_keys(current); + + task_lock(current); + unsafe = unsafe_exec(current); + security_bprm_apply_creds(bprm, unsafe); + task_unlock(current); + security_bprm_post_apply_creds(bprm); +} + +EXPORT_SYMBOL(compute_creds); + +void remove_arg_zero(struct linux_binprm *bprm) +{ + if (bprm->argc) { + unsigned long offset; + char * kaddr; + struct page *page; + + offset = bprm->p % PAGE_SIZE; + goto inside; + + while (bprm->p++, *(kaddr+offset++)) { + if (offset != PAGE_SIZE) + continue; + offset = 0; + kunmap_atomic(kaddr, KM_USER0); +inside: + page = bprm->page[bprm->p/PAGE_SIZE]; + kaddr = kmap_atomic(page, KM_USER0); + } + kunmap_atomic(kaddr, KM_USER0); + bprm->argc--; + } +} + +EXPORT_SYMBOL(remove_arg_zero); + +/* + * cycle the list of binary formats handler, until one recognizes the image + */ +int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs) +{ + int try,retval; + struct linux_binfmt *fmt; +#ifdef __alpha__ + /* handle /sbin/loader.. */ + { + struct exec * eh = (struct exec *) bprm->buf; + + if (!bprm->loader && eh->fh.f_magic == 0x183 && + (eh->fh.f_flags & 0x3000) == 0x3000) + { + struct file * file; + unsigned long loader; + + allow_write_access(bprm->file); + fput(bprm->file); + bprm->file = NULL; + + loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *); + + file = open_exec("/sbin/loader"); + retval = PTR_ERR(file); + if (IS_ERR(file)) + return retval; + + /* Remember if the application is TASO. */ + bprm->sh_bang = eh->ah.entry < 0x100000000UL; + + bprm->file = file; + bprm->loader = loader; + retval = prepare_binprm(bprm); + if (retval<0) + return retval; + /* should call search_binary_handler recursively here, + but it does not matter */ + } + } +#endif + retval = security_bprm_check(bprm); + if (retval) + return retval; + + /* kernel module loader fixup */ + /* so we don't try to load run modprobe in kernel space. */ + set_fs(USER_DS); + retval = -ENOENT; + for (try=0; try<2; try++) { + read_lock(&binfmt_lock); + for (fmt = formats ; fmt ; fmt = fmt->next) { + int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary; + if (!fn) + continue; + if (!try_module_get(fmt->module)) + continue; + read_unlock(&binfmt_lock); + retval = fn(bprm, regs); + if (retval >= 0) { + put_binfmt(fmt); + allow_write_access(bprm->file); + if (bprm->file) + fput(bprm->file); + bprm->file = NULL; + current->did_exec = 1; + return retval; + } + read_lock(&binfmt_lock); + put_binfmt(fmt); + if (retval != -ENOEXEC || bprm->mm == NULL) + break; + if (!bprm->file) { + read_unlock(&binfmt_lock); + return retval; + } + } + read_unlock(&binfmt_lock); + if (retval != -ENOEXEC || bprm->mm == NULL) { + break; +#ifdef CONFIG_KMOD + }else{ +#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e)) + if (printable(bprm->buf[0]) && + printable(bprm->buf[1]) && + printable(bprm->buf[2]) && + printable(bprm->buf[3])) + break; /* -ENOEXEC */ + request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2])); +#endif + } + } + return retval; +} + +EXPORT_SYMBOL(search_binary_handler); + +/* + * sys_execve() executes a new program. + */ +int do_execve(char * filename, + char __user *__user *argv, + char __user *__user *envp, + struct pt_regs * regs) +{ + struct linux_binprm *bprm; + struct file *file; + int retval; + int i; + + retval = -ENOMEM; + bprm = kmalloc(sizeof(*bprm), GFP_KERNEL); + if (!bprm) + goto out_ret; + memset(bprm, 0, sizeof(*bprm)); + + file = open_exec(filename); + retval = PTR_ERR(file); + if (IS_ERR(file)) + goto out_kfree; + + sched_exec(); + + bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *); + + bprm->file = file; + bprm->filename = filename; + bprm->interp = filename; + bprm->mm = mm_alloc(); + retval = -ENOMEM; + if (!bprm->mm) + goto out_file; + + retval = init_new_context(current, bprm->mm); + if (retval < 0) + goto out_mm; + + bprm->argc = count(argv, bprm->p / sizeof(void *)); + if ((retval = bprm->argc) < 0) + goto out_mm; + + bprm->envc = count(envp, bprm->p / sizeof(void *)); + if ((retval = bprm->envc) < 0) + goto out_mm; + + retval = security_bprm_alloc(bprm); + if (retval) + goto out; + + retval = prepare_binprm(bprm); + if (retval < 0) + goto out; + + retval = copy_strings_kernel(1, &bprm->filename, bprm); + if (retval < 0) + goto out; + + bprm->exec = bprm->p; + retval = copy_strings(bprm->envc, envp, bprm); + if (retval < 0) + goto out; + + retval = copy_strings(bprm->argc, argv, bprm); + if (retval < 0) + goto out; + + retval = search_binary_handler(bprm,regs); + if (retval >= 0) { + free_arg_pages(bprm); + + /* execve success */ + security_bprm_free(bprm); + acct_update_integrals(current); + update_mem_hiwater(current); + kfree(bprm); + return retval; + } + +out: + /* Something went wrong, return the inode and free the argument pages*/ + for (i = 0 ; i < MAX_ARG_PAGES ; i++) { + struct page * page = bprm->page[i]; + if (page) + __free_page(page); + } + + if (bprm->security) + security_bprm_free(bprm); + +out_mm: + if (bprm->mm) + mmdrop(bprm->mm); + +out_file: + if (bprm->file) { + allow_write_access(bprm->file); + fput(bprm->file); + } + +out_kfree: + kfree(bprm); + +out_ret: + return retval; +} + +int set_binfmt(struct linux_binfmt *new) +{ + struct linux_binfmt *old = current->binfmt; + + if (new) { + if (!try_module_get(new->module)) + return -1; + } + current->binfmt = new; + if (old) + module_put(old->module); + return 0; +} + +EXPORT_SYMBOL(set_binfmt); + +#define CORENAME_MAX_SIZE 64 + +/* format_corename will inspect the pattern parameter, and output a + * name into corename, which must have space for at least + * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator. + */ +static void format_corename(char *corename, const char *pattern, long signr) +{ + const char *pat_ptr = pattern; + char *out_ptr = corename; + char *const out_end = corename + CORENAME_MAX_SIZE; + int rc; + int pid_in_pattern = 0; + + /* Repeat as long as we have more pattern to process and more output + space */ + while (*pat_ptr) { + if (*pat_ptr != '%') { + if (out_ptr == out_end) + goto out; + *out_ptr++ = *pat_ptr++; + } else { + switch (*++pat_ptr) { + case 0: + goto out; + /* Double percent, output one percent */ + case '%': + if (out_ptr == out_end) + goto out; + *out_ptr++ = '%'; + break; + /* pid */ + case 'p': + pid_in_pattern = 1; + rc = snprintf(out_ptr, out_end - out_ptr, + "%d", current->tgid); + if (rc > out_end - out_ptr) + goto out; + out_ptr += rc; + break; + /* uid */ + case 'u': + rc = snprintf(out_ptr, out_end - out_ptr, + "%d", current->uid); + if (rc > out_end - out_ptr) + goto out; + out_ptr += rc; + break; + /* gid */ + case 'g': + rc = snprintf(out_ptr, out_end - out_ptr, + "%d", current->gid); + if (rc > out_end - out_ptr) + goto out; + out_ptr += rc; + break; + /* signal that caused the coredump */ + case 's': + rc = snprintf(out_ptr, out_end - out_ptr, + "%ld", signr); + if (rc > out_end - out_ptr) + goto out; + out_ptr += rc; + break; + /* UNIX time of coredump */ + case 't': { + struct timeval tv; + do_gettimeofday(&tv); + rc = snprintf(out_ptr, out_end - out_ptr, + "%lu", tv.tv_sec); + if (rc > out_end - out_ptr) + goto out; + out_ptr += rc; + break; + } + /* hostname */ + case 'h': + down_read(&uts_sem); + rc = snprintf(out_ptr, out_end - out_ptr, + "%s", system_utsname.nodename); + up_read(&uts_sem); + if (rc > out_end - out_ptr) + goto out; + out_ptr += rc; + break; + /* executable */ + case 'e': + rc = snprintf(out_ptr, out_end - out_ptr, + "%s", current->comm); + if (rc > out_end - out_ptr) + goto out; + out_ptr += rc; + break; + default: + break; + } + ++pat_ptr; + } + } + /* Backward compatibility with core_uses_pid: + * + * If core_pattern does not include a %p (as is the default) + * and core_uses_pid is set, then .%pid will be appended to + * the filename */ + if (!pid_in_pattern + && (core_uses_pid || atomic_read(¤t->mm->mm_users) != 1)) { + rc = snprintf(out_ptr, out_end - out_ptr, + ".%d", current->tgid); + if (rc > out_end - out_ptr) + goto out; + out_ptr += rc; + } + out: + *out_ptr = 0; +} + +static void zap_threads (struct mm_struct *mm) +{ + struct task_struct *g, *p; + struct task_struct *tsk = current; + struct completion *vfork_done = tsk->vfork_done; + int traced = 0; + + /* + * Make sure nobody is waiting for us to release the VM, + * otherwise we can deadlock when we wait on each other + */ + if (vfork_done) { + tsk->vfork_done = NULL; + complete(vfork_done); + } + + read_lock(&tasklist_lock); + do_each_thread(g,p) + if (mm == p->mm && p != tsk) { + force_sig_specific(SIGKILL, p); + mm->core_waiters++; + if (unlikely(p->ptrace) && + unlikely(p->parent->mm == mm)) + traced = 1; + } + while_each_thread(g,p); + + read_unlock(&tasklist_lock); + + if (unlikely(traced)) { + /* + * We are zapping a thread and the thread it ptraces. + * If the tracee went into a ptrace stop for exit tracing, + * we could deadlock since the tracer is waiting for this + * coredump to finish. Detach them so they can both die. + */ + write_lock_irq(&tasklist_lock); + do_each_thread(g,p) { + if (mm == p->mm && p != tsk && + p->ptrace && p->parent->mm == mm) { + __ptrace_unlink(p); + } + } while_each_thread(g,p); + write_unlock_irq(&tasklist_lock); + } +} + +static void coredump_wait(struct mm_struct *mm) +{ + DECLARE_COMPLETION(startup_done); + + mm->core_waiters++; /* let other threads block */ + mm->core_startup_done = &startup_done; + + /* give other threads a chance to run: */ + yield(); + + zap_threads(mm); + if (--mm->core_waiters) { + up_write(&mm->mmap_sem); + wait_for_completion(&startup_done); + } else + up_write(&mm->mmap_sem); + BUG_ON(mm->core_waiters); +} + +int do_coredump(long signr, int exit_code, struct pt_regs * regs) +{ + char corename[CORENAME_MAX_SIZE + 1]; + struct mm_struct *mm = current->mm; + struct linux_binfmt * binfmt; + struct inode * inode; + struct file * file; + int retval = 0; + + binfmt = current->binfmt; + if (!binfmt || !binfmt->core_dump) + goto fail; + down_write(&mm->mmap_sem); + if (!mm->dumpable) { + up_write(&mm->mmap_sem); + goto fail; + } + mm->dumpable = 0; + init_completion(&mm->core_done); + spin_lock_irq(¤t->sighand->siglock); + current->signal->flags = SIGNAL_GROUP_EXIT; + current->signal->group_exit_code = exit_code; + spin_unlock_irq(¤t->sighand->siglock); + coredump_wait(mm); + + /* + * Clear any false indication of pending signals that might + * be seen by the filesystem code called to write the core file. + */ + current->signal->group_stop_count = 0; + clear_thread_flag(TIF_SIGPENDING); + + if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump) + goto fail_unlock; + + /* + * lock_kernel() because format_corename() is controlled by sysctl, which + * uses lock_kernel() + */ + lock_kernel(); + format_corename(corename, core_pattern, signr); + unlock_kernel(); + file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE, 0600); + if (IS_ERR(file)) + goto fail_unlock; + inode = file->f_dentry->d_inode; + if (inode->i_nlink > 1) + goto close_fail; /* multiple links - don't dump */ + if (d_unhashed(file->f_dentry)) + goto close_fail; + + if (!S_ISREG(inode->i_mode)) + goto close_fail; + if (!file->f_op) + goto close_fail; + if (!file->f_op->write) + goto close_fail; + if (do_truncate(file->f_dentry, 0) != 0) + goto close_fail; + + retval = binfmt->core_dump(signr, regs, file); + + if (retval) + current->signal->group_exit_code |= 0x80; +close_fail: + filp_close(file, NULL); +fail_unlock: + complete_all(&mm->core_done); +fail: + return retval; +} |
