/* * 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"; int suid_dumpable = 0; EXPORT_SYMBOL(suid_dumpable); /* 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. */ static 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; else { /* * The SIGALRM timer survives the exec, but needs to point * at us as the new group leader now. We have a race with * a timer firing now getting the old leader, so we need to * synchronize with any firing (by calling del_timer_sync) * before we can safely let the old group leader die. */ sig->real_timer.data = (unsigned long)current; if (del_timer_sync(&sig->real_timer)) add_timer(&sig->real_timer); } 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; sig->real_timer.data = (unsigned long)current; 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); BUG_ON(leader->tgid != current->tgid); BUG_ON(current->pid == current->tgid); /* * 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); BUG_ON(exit_state != EXIT_ZOMBIE); 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); } BUG_ON(!thread_group_empty(current)); BUG_ON(!thread_group_leader(current)); 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; else current->mm->dumpable = suid_dumpable; name = bprm->filename; /* Copies the binary name from after last slash */ for (i=0; (ch = *(name++)) != '\0';) { if (ch == '/') i = 0; /* overwrite what we wrote */ 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 = suid_dumpable; } /* 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; int fsuid = current->fsuid; int flag = 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; } /* * We cannot trust fsuid as being the "true" uid of the * process nor do we know its entire history. We only know it * was tainted so we dump it as root in mode 2. */ if (mm->dumpable == 2) { /* Setuid core dump mode */ flag = O_EXCL; /* Stop rewrite attacks */ current->fsuid = 0; /* Dump root private */ } 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 | flag, 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: current->fsuid = fsuid; complete_all(&mm->core_done); fail: return retval; }