X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=fs%2Fexec.c;h=d49be6bc1793b57fdbfb5efc958311dd8f94801e;hb=0a3adadee42f2865bb867b8c5f4955b7def9baad;hp=cfb5656b2cdc1072cebe25b8bc9239efbf3e21bb;hpb=07edbde508869be63c38c5f2504bd8e8279cc535;p=safe%2Fjmp%2Flinux-2.6 diff --git a/fs/exec.c b/fs/exec.c index cfb5656..d49be6b 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -33,6 +33,7 @@ #include #include #include +#include #include #include #include @@ -45,27 +46,25 @@ #include #include #include +#include #include #include #include #include #include +#include +#include +#include +#include #include #include #include - -#ifdef CONFIG_KMOD -#include -#endif - -#ifdef __alpha__ -/* for /sbin/loader handling in search_binary_handler() */ -#include -#endif +#include "internal.h" int core_uses_pid; char core_pattern[CORENAME_MAX_SIZE] = "core"; +unsigned int core_pipe_limit; int suid_dumpable = 0; /* The maximal length of core_pattern is also specified in sysctl.c */ @@ -73,17 +72,18 @@ int suid_dumpable = 0; static LIST_HEAD(formats); static DEFINE_RWLOCK(binfmt_lock); -int register_binfmt(struct linux_binfmt * fmt) +int __register_binfmt(struct linux_binfmt * fmt, int insert) { if (!fmt) return -EINVAL; write_lock(&binfmt_lock); - list_add(&fmt->lh, &formats); + insert ? list_add(&fmt->lh, &formats) : + list_add_tail(&fmt->lh, &formats); write_unlock(&binfmt_lock); return 0; } -EXPORT_SYMBOL(register_binfmt); +EXPORT_SYMBOL(__register_binfmt); void unregister_binfmt(struct linux_binfmt * fmt) { @@ -105,38 +105,32 @@ static inline void put_binfmt(struct linux_binfmt * fmt) * * Also note that we take the address to load from from the file itself. */ -asmlinkage long sys_uselib(const char __user * library) +SYSCALL_DEFINE1(uselib, const char __user *, library) { struct file *file; - struct nameidata nd; char *tmp = getname(library); int error = PTR_ERR(tmp); - if (!IS_ERR(tmp)) { - error = path_lookup_open(AT_FDCWD, tmp, - LOOKUP_FOLLOW, &nd, - FMODE_READ|FMODE_EXEC); - putname(tmp); - } - if (error) + if (IS_ERR(tmp)) + goto out; + + file = do_filp_open(AT_FDCWD, tmp, + O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0, + MAY_READ | MAY_EXEC | MAY_OPEN); + putname(tmp); + error = PTR_ERR(file); + if (IS_ERR(file)) goto out; error = -EINVAL; - if (!S_ISREG(nd.path.dentry->d_inode->i_mode)) + if (!S_ISREG(file->f_path.dentry->d_inode->i_mode)) goto exit; error = -EACCES; - if (nd.path.mnt->mnt_flags & MNT_NOEXEC) + if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) goto exit; - error = vfs_permission(&nd, MAY_READ | MAY_EXEC | MAY_OPEN); - if (error) - goto exit; - - file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE); - error = PTR_ERR(file); - if (IS_ERR(file)) - goto out; + fsnotify_open(file->f_path.dentry); error = -ENOEXEC; if(file->f_op) { @@ -157,13 +151,10 @@ asmlinkage long sys_uselib(const char __user * library) } read_unlock(&binfmt_lock); } +exit: fput(file); out: return error; -exit: - release_open_intent(&nd); - path_put(&nd.path); - goto out; } #ifdef CONFIG_MMU @@ -235,13 +226,13 @@ static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, static int __bprm_mm_init(struct linux_binprm *bprm) { - int err = -ENOMEM; + int err; struct vm_area_struct *vma = NULL; struct mm_struct *mm = bprm->mm; bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); if (!vma) - goto err; + return -ENOMEM; down_write(&mm->mmap_sem); vma->vm_mm = mm; @@ -254,28 +245,20 @@ static int __bprm_mm_init(struct linux_binprm *bprm) */ vma->vm_end = STACK_TOP_MAX; vma->vm_start = vma->vm_end - PAGE_SIZE; - vma->vm_flags = VM_STACK_FLAGS; vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); err = insert_vm_struct(mm, vma); - if (err) { - up_write(&mm->mmap_sem); + if (err) goto err; - } mm->stack_vm = mm->total_vm = 1; up_write(&mm->mmap_sem); - bprm->p = vma->vm_end - sizeof(void *); - return 0; - err: - if (vma) { - bprm->vma = NULL; - kmem_cache_free(vm_area_cachep, vma); - } - + up_write(&mm->mmap_sem); + bprm->vma = NULL; + kmem_cache_free(vm_area_cachep, vma); return err; } @@ -666,48 +649,39 @@ EXPORT_SYMBOL(setup_arg_pages); struct file *open_exec(const char *name) { - struct nameidata nd; struct file *file; int err; - err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, - FMODE_READ|FMODE_EXEC); - if (err) + file = do_filp_open(AT_FDCWD, name, + O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0, + MAY_EXEC | MAY_OPEN); + if (IS_ERR(file)) goto out; err = -EACCES; - if (!S_ISREG(nd.path.dentry->d_inode->i_mode)) - goto out_path_put; - - if (nd.path.mnt->mnt_flags & MNT_NOEXEC) - goto out_path_put; + if (!S_ISREG(file->f_path.dentry->d_inode->i_mode)) + goto exit; - err = vfs_permission(&nd, MAY_EXEC | MAY_OPEN); - if (err) - goto out_path_put; + if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) + goto exit; - file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE); - if (IS_ERR(file)) - return file; + fsnotify_open(file->f_path.dentry); err = deny_write_access(file); - if (err) { - fput(file); - goto out; - } + if (err) + goto exit; +out: return file; - out_path_put: - release_open_intent(&nd); - path_put(&nd.path); - out: +exit: + fput(file); return ERR_PTR(err); } EXPORT_SYMBOL(open_exec); -int kernel_read(struct file *file, unsigned long offset, - char *addr, unsigned long count) +int kernel_read(struct file *file, loff_t offset, + char *addr, unsigned long count) { mm_segment_t old_fs; loff_t pos = offset; @@ -775,7 +749,6 @@ static int de_thread(struct task_struct *tsk) struct signal_struct *sig = tsk->signal; struct sighand_struct *oldsighand = tsk->sighand; spinlock_t *lock = &oldsighand->siglock; - struct task_struct *leader = NULL; int count; if (thread_group_empty(tsk)) @@ -813,7 +786,7 @@ static int de_thread(struct task_struct *tsk) * and to assume its PID: */ if (!thread_group_leader(tsk)) { - leader = tsk->group_leader; + struct task_struct *leader = tsk->group_leader; sig->notify_count = -1; /* for exit_notify() */ for (;;) { @@ -865,18 +838,20 @@ static int de_thread(struct task_struct *tsk) BUG_ON(leader->exit_state != EXIT_ZOMBIE); leader->exit_state = EXIT_DEAD; - write_unlock_irq(&tasklist_lock); + + release_task(leader); } sig->group_exit_task = NULL; sig->notify_count = 0; no_thread_group: + if (current->mm) + setmax_mm_hiwater_rss(&sig->maxrss, current->mm); + exit_itimers(sig); flush_itimer_signals(); - if (leader) - release_task(leader); if (atomic_read(&oldsighand->count) != 1) { struct sighand_struct *newsighand; @@ -953,6 +928,7 @@ void set_task_comm(struct task_struct *tsk, char *buf) task_lock(tsk); strlcpy(tsk->comm, buf, sizeof(tsk->comm)); task_unlock(tsk); + perf_event_comm(tsk); } int flush_old_exec(struct linux_binprm * bprm) @@ -983,7 +959,7 @@ int flush_old_exec(struct linux_binprm * bprm) /* This is the point of no return */ current->sas_ss_sp = current->sas_ss_size = 0; - if (current->euid == current->uid && current->egid == current->gid) + if (current_euid() == current_uid() && current_egid() == current_gid()) set_dumpable(current->mm, 1); else set_dumpable(current->mm, suid_dumpable); @@ -1010,16 +986,24 @@ int flush_old_exec(struct linux_binprm * bprm) */ current->mm->task_size = TASK_SIZE; - if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) { - suid_keys(current); - set_dumpable(current->mm, suid_dumpable); + /* install the new credentials */ + if (bprm->cred->uid != current_euid() || + bprm->cred->gid != current_egid()) { current->pdeath_signal = 0; } else if (file_permission(bprm->file, MAY_READ) || - (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) { - suid_keys(current); + bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) { set_dumpable(current->mm, suid_dumpable); } + current->personality &= ~bprm->per_clear; + + /* + * Flush performance counters when crossing a + * security domain: + */ + if (!get_dumpable(current->mm)) + perf_event_exit_task(current); + /* An exec changes our domain. We are no longer part of the thread group */ @@ -1036,13 +1020,99 @@ out: EXPORT_SYMBOL(flush_old_exec); +/* + * Prepare credentials and lock ->cred_guard_mutex. + * install_exec_creds() commits the new creds and drops the lock. + * Or, if exec fails before, free_bprm() should release ->cred and + * and unlock. + */ +int prepare_bprm_creds(struct linux_binprm *bprm) +{ + if (mutex_lock_interruptible(¤t->cred_guard_mutex)) + return -ERESTARTNOINTR; + + bprm->cred = prepare_exec_creds(); + if (likely(bprm->cred)) + return 0; + + mutex_unlock(¤t->cred_guard_mutex); + return -ENOMEM; +} + +void free_bprm(struct linux_binprm *bprm) +{ + free_arg_pages(bprm); + if (bprm->cred) { + mutex_unlock(¤t->cred_guard_mutex); + abort_creds(bprm->cred); + } + kfree(bprm); +} + +/* + * install the new credentials for this executable + */ +void install_exec_creds(struct linux_binprm *bprm) +{ + security_bprm_committing_creds(bprm); + + commit_creds(bprm->cred); + bprm->cred = NULL; + /* + * cred_guard_mutex must be held at least to this point to prevent + * ptrace_attach() from altering our determination of the task's + * credentials; any time after this it may be unlocked. + */ + security_bprm_committed_creds(bprm); + mutex_unlock(¤t->cred_guard_mutex); +} +EXPORT_SYMBOL(install_exec_creds); + +/* + * determine how safe it is to execute the proposed program + * - the caller must hold current->cred_guard_mutex to protect against + * PTRACE_ATTACH + */ +int check_unsafe_exec(struct linux_binprm *bprm) +{ + struct task_struct *p = current, *t; + unsigned n_fs; + int res = 0; + + bprm->unsafe = tracehook_unsafe_exec(p); + + n_fs = 1; + write_lock(&p->fs->lock); + rcu_read_lock(); + for (t = next_thread(p); t != p; t = next_thread(t)) { + if (t->fs == p->fs) + n_fs++; + } + rcu_read_unlock(); + + if (p->fs->users > n_fs) { + bprm->unsafe |= LSM_UNSAFE_SHARE; + } else { + res = -EAGAIN; + if (!p->fs->in_exec) { + p->fs->in_exec = 1; + res = 1; + } + } + write_unlock(&p->fs->lock); + + return res; +} + /* * Fill the binprm structure from the inode. * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes + * + * This may be called multiple times for binary chains (scripts for example). */ int prepare_binprm(struct linux_binprm *bprm) { - int mode; + umode_t mode; struct inode * inode = bprm->file->f_path.dentry->d_inode; int retval; @@ -1050,14 +1120,15 @@ int prepare_binprm(struct linux_binprm *bprm) if (bprm->file->f_op == NULL) return -EACCES; - bprm->e_uid = current->euid; - bprm->e_gid = current->egid; + /* clear any previous set[ug]id data from a previous binary */ + bprm->cred->euid = current_euid(); + bprm->cred->egid = current_egid(); - if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) { + if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) { /* Set-uid? */ if (mode & S_ISUID) { - current->personality &= ~PER_CLEAR_ON_SETID; - bprm->e_uid = inode->i_uid; + bprm->per_clear |= PER_CLEAR_ON_SETID; + bprm->cred->euid = inode->i_uid; } /* Set-gid? */ @@ -1067,52 +1138,23 @@ int prepare_binprm(struct linux_binprm *bprm) * executable. */ if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { - current->personality &= ~PER_CLEAR_ON_SETID; - bprm->e_gid = inode->i_gid; + bprm->per_clear |= PER_CLEAR_ON_SETID; + bprm->cred->egid = inode->i_gid; } } /* fill in binprm security blob */ - retval = security_bprm_set(bprm); + retval = security_bprm_set_creds(bprm); if (retval) return retval; + bprm->cred_prepared = 1; - memset(bprm->buf,0,BINPRM_BUF_SIZE); - return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE); + memset(bprm->buf, 0, BINPRM_BUF_SIZE); + return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE); } EXPORT_SYMBOL(prepare_binprm); -static int unsafe_exec(struct task_struct *p) -{ - int unsafe = tracehook_unsafe_exec(p); - - 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); - current->pdeath_signal = 0; - } - 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); - /* * Arguments are '\0' separated strings found at the location bprm->p * points to; chop off the first by relocating brpm->p to right after @@ -1162,46 +1204,16 @@ EXPORT_SYMBOL(remove_arg_zero); */ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs) { + unsigned int depth = bprm->recursion_depth; 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 = bprm->vma->vm_end - sizeof(void *); - - file = open_exec("/sbin/loader"); - retval = PTR_ERR(file); - if (IS_ERR(file)) - return retval; - - /* Remember if the application is TASO. */ - bprm->taso = 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; + retval = ima_bprm_check(bprm); + if (retval) + return retval; /* kernel module loader fixup */ /* so we don't try to load run modprobe in kernel space. */ @@ -1222,8 +1234,15 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs) continue; read_unlock(&binfmt_lock); retval = fn(bprm, regs); + /* + * Restore the depth counter to its starting value + * in this call, so we don't have to rely on every + * load_binary function to restore it on return. + */ + bprm->recursion_depth = depth; if (retval >= 0) { - tracehook_report_exec(fmt, bprm, regs); + if (depth == 0) + tracehook_report_exec(fmt, bprm, regs); put_binfmt(fmt); allow_write_access(bprm->file); if (bprm->file) @@ -1245,8 +1264,8 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs) read_unlock(&binfmt_lock); if (retval != -ENOEXEC || bprm->mm == NULL) { break; -#ifdef CONFIG_KMOD - }else{ +#ifdef CONFIG_MODULES + } else { #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e)) if (printable(bprm->buf[0]) && printable(bprm->buf[1]) && @@ -1262,12 +1281,6 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs) EXPORT_SYMBOL(search_binary_handler); -void free_bprm(struct linux_binprm *bprm) -{ - free_arg_pages(bprm); - kfree(bprm); -} - /* * sys_execve() executes a new program. */ @@ -1279,6 +1292,7 @@ int do_execve(char * filename, struct linux_binprm *bprm; struct file *file; struct files_struct *displaced; + bool clear_in_exec; int retval; retval = unshare_files(&displaced); @@ -1290,10 +1304,20 @@ int do_execve(char * filename, if (!bprm) goto out_files; + retval = prepare_bprm_creds(bprm); + if (retval) + goto out_free; + + retval = check_unsafe_exec(bprm); + if (retval < 0) + goto out_free; + clear_in_exec = retval; + current->in_execve = 1; + file = open_exec(filename); retval = PTR_ERR(file); if (IS_ERR(file)) - goto out_kfree; + goto out_unmark; sched_exec(); @@ -1307,14 +1331,10 @@ int do_execve(char * filename, bprm->argc = count(argv, MAX_ARG_STRINGS); if ((retval = bprm->argc) < 0) - goto out_mm; + goto out; bprm->envc = count(envp, MAX_ARG_STRINGS); if ((retval = bprm->envc) < 0) - goto out_mm; - - retval = security_bprm_alloc(bprm); - if (retval) goto out; retval = prepare_binprm(bprm); @@ -1336,21 +1356,21 @@ int do_execve(char * filename, current->flags &= ~PF_KTHREAD; retval = search_binary_handler(bprm,regs); - if (retval >= 0) { - /* execve success */ - security_bprm_free(bprm); - acct_update_integrals(current); - free_bprm(bprm); - if (displaced) - put_files_struct(displaced); - return retval; - } + if (retval < 0) + goto out; -out: - if (bprm->security) - security_bprm_free(bprm); + current->stack_start = current->mm->start_stack; -out_mm: + /* execve succeeded */ + current->fs->in_exec = 0; + current->in_execve = 0; + acct_update_integrals(current); + free_bprm(bprm); + if (displaced) + put_files_struct(displaced); + return retval; + +out: if (bprm->mm) mmput (bprm->mm); @@ -1359,7 +1379,13 @@ out_file: allow_write_access(bprm->file); fput(bprm->file); } -out_kfree: + +out_unmark: + if (clear_in_exec) + current->fs->in_exec = 0; + current->in_execve = 0; + +out_free: free_bprm(bprm); out_files: @@ -1369,18 +1395,16 @@ out_ret: return retval; } -int set_binfmt(struct linux_binfmt *new) +void set_binfmt(struct linux_binfmt *new) { - struct linux_binfmt *old = current->binfmt; + struct mm_struct *mm = current->mm; - if (new) { - if (!try_module_get(new->module)) - return -1; - } - current->binfmt = new; - if (old) - module_put(old->module); - return 0; + if (mm->binfmt) + module_put(mm->binfmt->module); + + mm->binfmt = new; + if (new) + __module_get(new->module); } EXPORT_SYMBOL(set_binfmt); @@ -1389,8 +1413,9 @@ EXPORT_SYMBOL(set_binfmt); * name into corename, which must have space for at least * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator. */ -static int format_corename(char *corename, int nr_threads, long signr) +static int format_corename(char *corename, long signr) { + const struct cred *cred = current_cred(); const char *pat_ptr = core_pattern; int ispipe = (*pat_ptr == '|'); char *out_ptr = corename; @@ -1427,7 +1452,7 @@ static int format_corename(char *corename, int nr_threads, long signr) /* uid */ case 'u': rc = snprintf(out_ptr, out_end - out_ptr, - "%d", current->uid); + "%d", cred->uid); if (rc > out_end - out_ptr) goto out; out_ptr += rc; @@ -1435,7 +1460,7 @@ static int format_corename(char *corename, int nr_threads, long signr) /* gid */ case 'g': rc = snprintf(out_ptr, out_end - out_ptr, - "%d", current->gid); + "%d", cred->gid); if (rc > out_end - out_ptr) goto out; out_ptr += rc; @@ -1496,8 +1521,7 @@ static int format_corename(char *corename, int nr_threads, long signr) * 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. Do not do this for piped commands. */ - if (!ispipe && !pid_in_pattern - && (core_uses_pid || nr_threads)) { + if (!ispipe && !pid_in_pattern && core_uses_pid) { rc = snprintf(out_ptr, out_end - out_ptr, ".%d", task_tgid_vnr(current)); if (rc > out_end - out_ptr) @@ -1704,7 +1728,30 @@ int get_dumpable(struct mm_struct *mm) return (ret >= 2) ? 2 : ret; } -int do_coredump(long signr, int exit_code, struct pt_regs * regs) +static void wait_for_dump_helpers(struct file *file) +{ + struct pipe_inode_info *pipe; + + pipe = file->f_path.dentry->d_inode->i_pipe; + + pipe_lock(pipe); + pipe->readers++; + pipe->writers--; + + while ((pipe->readers > 1) && (!signal_pending(current))) { + wake_up_interruptible_sync(&pipe->wait); + kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); + pipe_wait(pipe); + } + + pipe->readers--; + pipe->writers++; + pipe_unlock(pipe); + +} + + +void do_coredump(long signr, int exit_code, struct pt_regs *regs) { struct core_state core_state; char corename[CORENAME_MAX_SIZE + 1]; @@ -1712,26 +1759,36 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs) struct linux_binfmt * binfmt; struct inode * inode; struct file * file; + const struct cred *old_cred; + struct cred *cred; int retval = 0; - int fsuid = current->fsuid; int flag = 0; int ispipe = 0; unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur; char **helper_argv = NULL; int helper_argc = 0; - char *delimit; + int dump_count = 0; + static atomic_t core_dump_count = ATOMIC_INIT(0); audit_core_dumps(signr); - binfmt = current->binfmt; + binfmt = mm->binfmt; if (!binfmt || !binfmt->core_dump) goto fail; + + cred = prepare_creds(); + if (!cred) { + retval = -ENOMEM; + goto fail; + } + down_write(&mm->mmap_sem); /* * If another thread got here first, or we are not dumpable, bail out. */ if (mm->core_state || !get_dumpable(mm)) { up_write(&mm->mmap_sem); + put_cred(cred); goto fail; } @@ -1742,12 +1799,16 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs) */ if (get_dumpable(mm) == 2) { /* Setuid core dump mode */ flag = O_EXCL; /* Stop rewrite attacks */ - current->fsuid = 0; /* Dump root private */ + cred->fsuid = 0; /* Dump root private */ } retval = coredump_wait(exit_code, &core_state); - if (retval < 0) + if (retval < 0) { + put_cred(cred); goto fail; + } + + old_cred = override_creds(cred); /* * Clear any false indication of pending signals that might @@ -1760,51 +1821,65 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs) * uses lock_kernel() */ lock_kernel(); - ispipe = format_corename(corename, retval, signr); + ispipe = format_corename(corename, signr); unlock_kernel(); - /* - * Don't bother to check the RLIMIT_CORE value if core_pattern points - * to a pipe. Since we're not writing directly to the filesystem - * RLIMIT_CORE doesn't really apply, as no actual core file will be - * created unless the pipe reader choses to write out the core file - * at which point file size limits and permissions will be imposed - * as it does with any other process - */ + if ((!ispipe) && (core_limit < binfmt->min_coredump)) goto fail_unlock; if (ispipe) { - helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc); - /* Terminate the string before the first option */ - delimit = strchr(corename, ' '); - if (delimit) - *delimit = '\0'; - delimit = strrchr(helper_argv[0], '/'); - if (delimit) - delimit++; - else - delimit = helper_argv[0]; - if (!strcmp(delimit, current->comm)) { - printk(KERN_NOTICE "Recursive core dump detected, " - "aborting\n"); + if (core_limit == 0) { + /* + * Normally core limits are irrelevant to pipes, since + * we're not writing to the file system, but we use + * core_limit of 0 here as a speacial value. Any + * non-zero limit gets set to RLIM_INFINITY below, but + * a limit of 0 skips the dump. This is a consistent + * way to catch recursive crashes. We can still crash + * if the core_pattern binary sets RLIM_CORE = !0 + * but it runs as root, and can do lots of stupid things + * Note that we use task_tgid_vnr here to grab the pid + * of the process group leader. That way we get the + * right pid if a thread in a multi-threaded + * core_pattern process dies. + */ + printk(KERN_WARNING + "Process %d(%s) has RLIMIT_CORE set to 0\n", + task_tgid_vnr(current), current->comm); + printk(KERN_WARNING "Aborting core\n"); goto fail_unlock; } + dump_count = atomic_inc_return(&core_dump_count); + if (core_pipe_limit && (core_pipe_limit < dump_count)) { + printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n", + task_tgid_vnr(current), current->comm); + printk(KERN_WARNING "Skipping core dump\n"); + goto fail_dropcount; + } + + helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc); + if (!helper_argv) { + printk(KERN_WARNING "%s failed to allocate memory\n", + __func__); + goto fail_dropcount; + } + core_limit = RLIM_INFINITY; /* SIGPIPE can happen, but it's just never processed */ - if (call_usermodehelper_pipe(corename+1, helper_argv, NULL, + if (call_usermodehelper_pipe(helper_argv[0], helper_argv, NULL, &file)) { printk(KERN_INFO "Core dump to %s pipe failed\n", corename); - goto fail_unlock; + goto fail_dropcount; } } else file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, 0600); if (IS_ERR(file)) - goto fail_unlock; + goto fail_dropcount; inode = file->f_path.dentry->d_inode; if (inode->i_nlink > 1) goto close_fail; /* multiple links - don't dump */ @@ -1819,7 +1894,7 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs) * Dont allow local users get cute and trick others to coredump * into their pre-created files: */ - if (inode->i_uid != current->fsuid) + if (inode->i_uid != current_fsuid()) goto close_fail; if (!file->f_op) goto close_fail; @@ -1833,13 +1908,19 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs) if (retval) current->signal->group_exit_code |= 0x80; close_fail: + if (ispipe && core_pipe_limit) + wait_for_dump_helpers(file); filp_close(file, NULL); +fail_dropcount: + if (dump_count) + atomic_dec(&core_dump_count); fail_unlock: if (helper_argv) argv_free(helper_argv); - current->fsuid = fsuid; + revert_creds(old_cred); + put_cred(cred); coredump_finish(mm); fail: - return retval; + return; }