diff options
Diffstat (limited to 'kernel/seccomp.c')
| -rw-r--r-- | kernel/seccomp.c | 84 |
1 files changed, 74 insertions, 10 deletions
diff --git a/kernel/seccomp.c b/kernel/seccomp.c index d3e584065c7f..255999ba9190 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -110,11 +110,13 @@ struct seccomp_knotif { * @flags: The flags for the new file descriptor. At the moment, only O_CLOEXEC * is allowed. * @ioctl_flags: The flags used for the seccomp_addfd ioctl. + * @setfd: whether or not SECCOMP_ADDFD_FLAG_SETFD was set during notify_addfd * @ret: The return value of the installing process. It is set to the fd num * upon success (>= 0). * @completion: Indicates that the installing process has completed fd * installation, or gone away (either due to successful * reply, or signal) + * @list: list_head for chaining seccomp_kaddfd together. * */ struct seccomp_kaddfd { @@ -138,14 +140,17 @@ struct seccomp_kaddfd { * structure is fairly large, we store the notification-specific stuff in a * separate structure. * - * @request: A semaphore that users of this notification can wait on for - * changes. Actual reads and writes are still controlled with - * filter->notify_lock. + * @requests: A semaphore that users of this notification can wait on for + * changes. Actual reads and writes are still controlled with + * filter->notify_lock. + * @flags: A set of SECCOMP_USER_NOTIF_FD_* flags. * @next_id: The id of the next request. * @notifications: A list of struct seccomp_knotif elements. */ + struct notification { - struct semaphore request; + atomic_t requests; + u32 flags; u64 next_id; struct list_head notifications; }; @@ -555,6 +560,8 @@ static void __seccomp_filter_release(struct seccomp_filter *orig) * drop its reference count, and notify * about unused filters * + * @tsk: task the filter should be released from. + * * 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. @@ -574,6 +581,8 @@ void seccomp_filter_release(struct task_struct *tsk) /** * seccomp_sync_threads: sets all threads to use current's filter * + * @flags: SECCOMP_FILTER_FLAG_* flags to set during sync. + * * Expects sighand and cred_guard_mutex locks to be held, and for * seccomp_can_sync_threads() to have returned success already * without dropping the locks. @@ -1116,8 +1125,11 @@ static int seccomp_do_user_notification(int this_syscall, list_add_tail(&n.list, &match->notif->notifications); INIT_LIST_HEAD(&n.addfd); - up(&match->notif->request); - wake_up_poll(&match->wqh, EPOLLIN | EPOLLRDNORM); + atomic_inc(&match->notif->requests); + if (match->notif->flags & SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP) + wake_up_poll_on_current_cpu(&match->wqh, EPOLLIN | EPOLLRDNORM); + else + wake_up_poll(&match->wqh, EPOLLIN | EPOLLRDNORM); /* * This is where we wait for a reply from userspace. @@ -1450,6 +1462,37 @@ find_notification(struct seccomp_filter *filter, u64 id) return NULL; } +static int recv_wake_function(wait_queue_entry_t *wait, unsigned int mode, int sync, + void *key) +{ + /* Avoid a wakeup if event not interesting for us. */ + if (key && !(key_to_poll(key) & (EPOLLIN | EPOLLERR))) + return 0; + return autoremove_wake_function(wait, mode, sync, key); +} + +static int recv_wait_event(struct seccomp_filter *filter) +{ + DEFINE_WAIT_FUNC(wait, recv_wake_function); + int ret; + + if (atomic_dec_if_positive(&filter->notif->requests) >= 0) + return 0; + + for (;;) { + ret = prepare_to_wait_event(&filter->wqh, &wait, TASK_INTERRUPTIBLE); + + if (atomic_dec_if_positive(&filter->notif->requests) >= 0) + break; + + if (ret) + return ret; + + schedule(); + } + finish_wait(&filter->wqh, &wait); + return 0; +} static long seccomp_notify_recv(struct seccomp_filter *filter, void __user *buf) @@ -1467,7 +1510,7 @@ static long seccomp_notify_recv(struct seccomp_filter *filter, memset(&unotif, 0, sizeof(unotif)); - ret = down_interruptible(&filter->notif->request); + ret = recv_wait_event(filter); if (ret < 0) return ret; @@ -1515,7 +1558,8 @@ out: if (should_sleep_killable(filter, knotif)) complete(&knotif->ready); knotif->state = SECCOMP_NOTIFY_INIT; - up(&filter->notif->request); + atomic_inc(&filter->notif->requests); + wake_up_poll(&filter->wqh, EPOLLIN | EPOLLRDNORM); } mutex_unlock(&filter->notify_lock); } @@ -1561,7 +1605,10 @@ static long seccomp_notify_send(struct seccomp_filter *filter, knotif->error = resp.error; knotif->val = resp.val; knotif->flags = resp.flags; - complete(&knotif->ready); + if (filter->notif->flags & SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP) + complete_on_current_cpu(&knotif->ready); + else + complete(&knotif->ready); out: mutex_unlock(&filter->notify_lock); return ret; @@ -1591,6 +1638,22 @@ static long seccomp_notify_id_valid(struct seccomp_filter *filter, return ret; } +static long seccomp_notify_set_flags(struct seccomp_filter *filter, + unsigned long flags) +{ + long ret; + + if (flags & ~SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP) + return -EINVAL; + + ret = mutex_lock_interruptible(&filter->notify_lock); + if (ret < 0) + return ret; + filter->notif->flags = flags; + mutex_unlock(&filter->notify_lock); + return 0; +} + static long seccomp_notify_addfd(struct seccomp_filter *filter, struct seccomp_notif_addfd __user *uaddfd, unsigned int size) @@ -1720,6 +1783,8 @@ static long seccomp_notify_ioctl(struct file *file, unsigned int cmd, case SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR: case SECCOMP_IOCTL_NOTIF_ID_VALID: return seccomp_notify_id_valid(filter, buf); + case SECCOMP_IOCTL_NOTIF_SET_FLAGS: + return seccomp_notify_set_flags(filter, arg); } /* Extensible Argument ioctls */ @@ -1777,7 +1842,6 @@ static struct file *init_listener(struct seccomp_filter *filter) if (!filter->notif) goto out; - sema_init(&filter->notif->request, 0); filter->notif->next_id = get_random_u64(); INIT_LIST_HEAD(&filter->notif->notifications); |