diff options
| -rw-r--r-- | include/linux/seccomp.h | 4 | ||||
| -rw-r--r-- | kernel/exit.c | 1 | ||||
| -rw-r--r-- | kernel/fork.c | 1 | ||||
| -rw-r--r-- | kernel/seccomp.c | 62 |
4 files changed, 40 insertions, 28 deletions
diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h index 2ec2720f83cc..babcd6c02d09 100644 --- a/include/linux/seccomp.h +++ b/include/linux/seccomp.h @@ -84,10 +84,10 @@ static inline int seccomp_mode(struct seccomp *s) #endif /* CONFIG_SECCOMP */ #ifdef CONFIG_SECCOMP_FILTER -extern void put_seccomp_filter(struct task_struct *tsk); +extern void seccomp_filter_release(struct task_struct *tsk); extern void get_seccomp_filter(struct task_struct *tsk); #else /* CONFIG_SECCOMP_FILTER */ -static inline void put_seccomp_filter(struct task_struct *tsk) +static inline void seccomp_filter_release(struct task_struct *tsk) { return; } diff --git a/kernel/exit.c b/kernel/exit.c index 727150f28103..00d77e5ba700 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -217,6 +217,7 @@ repeat: } write_unlock_irq(&tasklist_lock); + seccomp_filter_release(p); proc_flush_pid(thread_pid); put_pid(thread_pid); release_thread(p); diff --git a/kernel/fork.c b/kernel/fork.c index 142b23645d82..c51a9cd824c5 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -473,7 +473,6 @@ void free_task(struct task_struct *tsk) #endif rt_mutex_debug_task_free(tsk); ftrace_graph_exit_task(tsk); - put_seccomp_filter(tsk); arch_release_task_struct(tsk); if (tsk->flags & PF_KTHREAD) free_kthread_struct(tsk); diff --git a/kernel/seccomp.c b/kernel/seccomp.c index d4dd3344e312..0ca6d5243427 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -368,6 +368,42 @@ static inline pid_t seccomp_can_sync_threads(void) return 0; } +static inline void seccomp_filter_free(struct seccomp_filter *filter) +{ + if (filter) { + bpf_prog_destroy(filter->prog); + kfree(filter); + } +} + +static void __put_seccomp_filter(struct seccomp_filter *orig) +{ + /* Clean up single-reference branches iteratively. */ + while (orig && refcount_dec_and_test(&orig->refs)) { + struct seccomp_filter *freeme = orig; + orig = orig->prev; + seccomp_filter_free(freeme); + } +} + +/** + * seccomp_filter_release - Detach the task from its filter tree + * and drop its reference count during + * exit. + * + * This function should only be called when the task is exiting as + * it detaches it from its filter tree. As such, READ_ONCE() and + * barriers are not needed here, as would normally be needed. + */ +void seccomp_filter_release(struct task_struct *tsk) +{ + struct seccomp_filter *orig = tsk->seccomp.filter; + + /* Detach task from its filter tree. */ + tsk->seccomp.filter = NULL; + __put_seccomp_filter(orig); +} + /** * seccomp_sync_threads: sets all threads to use current's filter * @@ -397,7 +433,7 @@ static inline void seccomp_sync_threads(unsigned long flags) * current's path will hold a reference. (This also * allows a put before the assignment.) */ - put_seccomp_filter(thread); + __put_seccomp_filter(thread->seccomp.filter); smp_store_release(&thread->seccomp.filter, caller->seccomp.filter); atomic_set(&thread->seccomp.filter_count, @@ -571,30 +607,6 @@ void get_seccomp_filter(struct task_struct *tsk) __get_seccomp_filter(orig); } -static inline void seccomp_filter_free(struct seccomp_filter *filter) -{ - if (filter) { - bpf_prog_destroy(filter->prog); - kfree(filter); - } -} - -static void __put_seccomp_filter(struct seccomp_filter *orig) -{ - /* Clean up single-reference branches iteratively. */ - while (orig && refcount_dec_and_test(&orig->refs)) { - struct seccomp_filter *freeme = orig; - orig = orig->prev; - seccomp_filter_free(freeme); - } -} - -/* put_seccomp_filter - decrements the ref count of tsk->seccomp.filter */ -void put_seccomp_filter(struct task_struct *tsk) -{ - __put_seccomp_filter(tsk->seccomp.filter); -} - static void seccomp_init_siginfo(kernel_siginfo_t *info, int syscall, int reason) { clear_siginfo(info); |