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Diffstat (limited to 'kernel/seccomp.c')
-rw-r--r--kernel/seccomp.c44
1 files changed, 41 insertions, 3 deletions
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index b5ac87f6dbd4..e9852d1b4a5e 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -200,6 +200,8 @@ static inline void seccomp_cache_prepare(struct seccomp_filter *sfilter)
* the filter can be freed.
* @cache: cache of arch/syscall mappings to actions
* @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
+ * @wait_killable_recv: Put notifying process in killable state once the
+ * notification is received by the userspace listener.
* @prev: points to a previously installed, or inherited, filter
* @prog: the BPF program to evaluate
* @notif: the struct that holds all notification related information
@@ -220,6 +222,7 @@ struct seccomp_filter {
refcount_t refs;
refcount_t users;
bool log;
+ bool wait_killable_recv;
struct action_cache cache;
struct seccomp_filter *prev;
struct bpf_prog *prog;
@@ -893,6 +896,10 @@ static long seccomp_attach_filter(unsigned int flags,
if (flags & SECCOMP_FILTER_FLAG_LOG)
filter->log = true;
+ /* Set wait killable flag, if present. */
+ if (flags & SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV)
+ filter->wait_killable_recv = true;
+
/*
* If there is an existing filter, make it the prev and don't drop its
* task reference.
@@ -1080,6 +1087,12 @@ static void seccomp_handle_addfd(struct seccomp_kaddfd *addfd, struct seccomp_kn
complete(&addfd->completion);
}
+static bool should_sleep_killable(struct seccomp_filter *match,
+ struct seccomp_knotif *n)
+{
+ return match->wait_killable_recv && n->state == SECCOMP_NOTIFY_SENT;
+}
+
static int seccomp_do_user_notification(int this_syscall,
struct seccomp_filter *match,
const struct seccomp_data *sd)
@@ -1100,7 +1113,7 @@ static int seccomp_do_user_notification(int this_syscall,
n.data = sd;
n.id = seccomp_next_notify_id(match);
init_completion(&n.ready);
- list_add(&n.list, &match->notif->notifications);
+ list_add_tail(&n.list, &match->notif->notifications);
INIT_LIST_HEAD(&n.addfd);
up(&match->notif->request);
@@ -1110,11 +1123,25 @@ static int seccomp_do_user_notification(int this_syscall,
* This is where we wait for a reply from userspace.
*/
do {
+ bool wait_killable = should_sleep_killable(match, &n);
+
mutex_unlock(&match->notify_lock);
- err = wait_for_completion_interruptible(&n.ready);
+ if (wait_killable)
+ err = wait_for_completion_killable(&n.ready);
+ else
+ err = wait_for_completion_interruptible(&n.ready);
mutex_lock(&match->notify_lock);
- if (err != 0)
+
+ if (err != 0) {
+ /*
+ * Check to see if the notifcation got picked up and
+ * whether we should switch to wait killable.
+ */
+ if (!wait_killable && should_sleep_killable(match, &n))
+ continue;
+
goto interrupted;
+ }
addfd = list_first_entry_or_null(&n.addfd,
struct seccomp_kaddfd, list);
@@ -1484,6 +1511,9 @@ out:
mutex_lock(&filter->notify_lock);
knotif = find_notification(filter, unotif.id);
if (knotif) {
+ /* Reset the process to make sure it's not stuck */
+ if (should_sleep_killable(filter, knotif))
+ complete(&knotif->ready);
knotif->state = SECCOMP_NOTIFY_INIT;
up(&filter->notif->request);
}
@@ -1829,6 +1859,14 @@ static long seccomp_set_mode_filter(unsigned int flags,
((flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH) == 0))
return -EINVAL;
+ /*
+ * The SECCOMP_FILTER_FLAG_WAIT_KILLABLE_SENT flag doesn't make sense
+ * without the SECCOMP_FILTER_FLAG_NEW_LISTENER flag.
+ */
+ if ((flags & SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV) &&
+ ((flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) == 0))
+ return -EINVAL;
+
/* Prepare the new filter before holding any locks. */
prepared = seccomp_prepare_user_filter(filter);
if (IS_ERR(prepared))