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https://github.com/torvalds/linux
synced 2024-09-06 09:51:23 +00:00
signals: move cred_guard_mutex from task_struct to signal_struct
Oleg Nesterov pointed out we have to prevent multiple-threads-inside-exec itself and we can reuse ->cred_guard_mutex for it. Yes, concurrent execve() has no worth. Let's move ->cred_guard_mutex from task_struct to signal_struct. It naturally prevent multiple-threads-inside-exec. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Roland McGrath <roland@redhat.com> Acked-by: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
b840115083
commit
9b1bf12d5d
10
fs/exec.c
10
fs/exec.c
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@ -1083,14 +1083,14 @@ EXPORT_SYMBOL(setup_new_exec);
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*/
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int prepare_bprm_creds(struct linux_binprm *bprm)
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{
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if (mutex_lock_interruptible(¤t->cred_guard_mutex))
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if (mutex_lock_interruptible(¤t->signal->cred_guard_mutex))
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return -ERESTARTNOINTR;
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bprm->cred = prepare_exec_creds();
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if (likely(bprm->cred))
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return 0;
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mutex_unlock(¤t->cred_guard_mutex);
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mutex_unlock(¤t->signal->cred_guard_mutex);
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return -ENOMEM;
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}
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@ -1098,7 +1098,7 @@ void free_bprm(struct linux_binprm *bprm)
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{
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free_arg_pages(bprm);
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if (bprm->cred) {
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mutex_unlock(¤t->cred_guard_mutex);
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mutex_unlock(¤t->signal->cred_guard_mutex);
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abort_creds(bprm->cred);
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}
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kfree(bprm);
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@ -1119,13 +1119,13 @@ void install_exec_creds(struct linux_binprm *bprm)
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* credentials; any time after this it may be unlocked.
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*/
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security_bprm_committed_creds(bprm);
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mutex_unlock(¤t->cred_guard_mutex);
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mutex_unlock(¤t->signal->cred_guard_mutex);
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}
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EXPORT_SYMBOL(install_exec_creds);
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/*
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* determine how safe it is to execute the proposed program
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* - the caller must hold current->cred_guard_mutex to protect against
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* - the caller must hold ->cred_guard_mutex to protect against
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* PTRACE_ATTACH
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*/
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int check_unsafe_exec(struct linux_binprm *bprm)
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@ -226,7 +226,7 @@ struct mm_struct *mm_for_maps(struct task_struct *task)
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{
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struct mm_struct *mm;
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if (mutex_lock_killable(&task->cred_guard_mutex))
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if (mutex_lock_killable(&task->signal->cred_guard_mutex))
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return NULL;
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mm = get_task_mm(task);
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@ -235,7 +235,7 @@ struct mm_struct *mm_for_maps(struct task_struct *task)
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mmput(mm);
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mm = NULL;
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}
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mutex_unlock(&task->cred_guard_mutex);
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mutex_unlock(&task->signal->cred_guard_mutex);
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return mm;
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}
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@ -2354,14 +2354,14 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
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goto out_free;
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/* Guard against adverse ptrace interaction */
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length = mutex_lock_interruptible(&task->cred_guard_mutex);
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length = mutex_lock_interruptible(&task->signal->cred_guard_mutex);
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if (length < 0)
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goto out_free;
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length = security_setprocattr(task,
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(char*)file->f_path.dentry->d_name.name,
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(void*)page, count);
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mutex_unlock(&task->cred_guard_mutex);
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mutex_unlock(&task->signal->cred_guard_mutex);
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out_free:
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free_page((unsigned long) page);
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out:
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@ -29,6 +29,8 @@ extern struct fs_struct init_fs;
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.running = 0, \
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.lock = __SPIN_LOCK_UNLOCKED(sig.cputimer.lock), \
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}, \
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.cred_guard_mutex = \
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__MUTEX_INITIALIZER(sig.cred_guard_mutex), \
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}
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extern struct nsproxy init_nsproxy;
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@ -145,8 +147,6 @@ extern struct cred init_cred;
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.group_leader = &tsk, \
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RCU_INIT_POINTER(.real_cred, &init_cred), \
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RCU_INIT_POINTER(.cred, &init_cred), \
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.cred_guard_mutex = \
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__MUTEX_INITIALIZER(tsk.cred_guard_mutex), \
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.comm = "swapper", \
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.thread = INIT_THREAD, \
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.fs = &init_fs, \
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@ -626,6 +626,10 @@ struct signal_struct {
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int oom_adj; /* OOM kill score adjustment (bit shift) */
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int oom_score_adj; /* OOM kill score adjustment */
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struct mutex cred_guard_mutex; /* guard against foreign influences on
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* credential calculations
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* (notably. ptrace) */
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};
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/* Context switch must be unlocked if interrupts are to be enabled */
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@ -1305,9 +1309,6 @@ struct task_struct {
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* credentials (COW) */
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const struct cred __rcu *cred; /* effective (overridable) subjective task
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* credentials (COW) */
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struct mutex cred_guard_mutex; /* guard against foreign influences on
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* credential calculations
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* (notably. ptrace) */
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struct cred *replacement_session_keyring; /* for KEYCTL_SESSION_TO_PARENT */
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char comm[TASK_COMM_LEN]; /* executable name excluding path
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@ -150,7 +150,7 @@ static inline void tracehook_report_syscall_exit(struct pt_regs *regs, int step)
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*
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* Return %LSM_UNSAFE_* bits applied to an exec because of tracing.
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*
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* @task->cred_guard_mutex is held by the caller through the do_execve().
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* @task->signal->cred_guard_mutex is held by the caller through the do_execve().
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*/
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static inline int tracehook_unsafe_exec(struct task_struct *task)
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{
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@ -325,7 +325,7 @@ EXPORT_SYMBOL(prepare_creds);
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/*
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* Prepare credentials for current to perform an execve()
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* - The caller must hold current->cred_guard_mutex
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* - The caller must hold ->cred_guard_mutex
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*/
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struct cred *prepare_exec_creds(void)
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{
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@ -384,8 +384,6 @@ int copy_creds(struct task_struct *p, unsigned long clone_flags)
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struct cred *new;
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int ret;
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mutex_init(&p->cred_guard_mutex);
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if (
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#ifdef CONFIG_KEYS
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!p->cred->thread_keyring &&
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@ -908,6 +908,8 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
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sig->oom_adj = current->signal->oom_adj;
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sig->oom_score_adj = current->signal->oom_score_adj;
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mutex_init(&sig->cred_guard_mutex);
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return 0;
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}
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@ -181,7 +181,7 @@ int ptrace_attach(struct task_struct *task)
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* under ptrace.
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*/
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retval = -ERESTARTNOINTR;
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if (mutex_lock_interruptible(&task->cred_guard_mutex))
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if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
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goto out;
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task_lock(task);
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@ -208,7 +208,7 @@ int ptrace_attach(struct task_struct *task)
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unlock_tasklist:
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write_unlock_irq(&tasklist_lock);
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unlock_creds:
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mutex_unlock(&task->cred_guard_mutex);
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mutex_unlock(&task->signal->cred_guard_mutex);
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out:
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return retval;
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}
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