diff options
| author | Kuniyuki Iwashima <kuniyu@google.com> | 2025-11-15 02:08:35 +0000 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-11-18 19:19:31 -0800 |
| commit | 384900542dc85f3aac7918fea8e7ef62141e3ea6 (patch) | |
| tree | b1cd2cb95b8592913248116847f820c8565129e6 | |
| parent | da8fc7a39be897426e1ac05aa90263abf40621b7 (diff) | |
af_unix: Don't call wait_for_unix_gc() on every sendmsg().
We have been calling wait_for_unix_gc() on every sendmsg() in case
there are too many inflight AF_UNIX sockets.
This is also because the old GC implementation had poor knowledge
of the inflight sockets and had to suspect every sendmsg().
This was improved by commit d9f21b361333 ("af_unix: Try to run GC
async."), but we do not even need to call wait_for_unix_gc() if the
process is not sending AF_UNIX sockets.
The wait_for_unix_gc() call only helps when a malicious process
continues to create cyclic references, and we can detect that
in a better place and slow it down.
Let's move wait_for_unix_gc() to unix_prepare_fpl() that is called
only when AF_UNIX socket fd is passed via SCM_RIGHTS.
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20251115020935.2643121-5-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | net/unix/af_unix.c | 4 | ||||
| -rw-r--r-- | net/unix/af_unix.h | 1 | ||||
| -rw-r--r-- | net/unix/garbage.c | 9 |
3 files changed, 6 insertions, 8 deletions
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 4a80dac56bbd..34952242bd81 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -2098,8 +2098,6 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg, if (err < 0) return err; - wait_for_unix_gc(scm.fp); - if (msg->msg_flags & MSG_OOB) { err = -EOPNOTSUPP; goto out; @@ -2393,8 +2391,6 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg, if (err < 0) return err; - wait_for_unix_gc(scm.fp); - if (msg->msg_flags & MSG_OOB) { err = -EOPNOTSUPP; #if IS_ENABLED(CONFIG_AF_UNIX_OOB) diff --git a/net/unix/af_unix.h b/net/unix/af_unix.h index 0fb5b348ad94..2f1bfe3217c1 100644 --- a/net/unix/af_unix.h +++ b/net/unix/af_unix.h @@ -30,7 +30,6 @@ void unix_update_edges(struct unix_sock *receiver); int unix_prepare_fpl(struct scm_fp_list *fpl); void unix_destroy_fpl(struct scm_fp_list *fpl); void unix_schedule_gc(void); -void wait_for_unix_gc(struct scm_fp_list *fpl); /* SOCK_DIAG */ long unix_inq_len(struct sock *sk); diff --git a/net/unix/garbage.c b/net/unix/garbage.c index 190dea73f0ab..280b9b07b1c0 100644 --- a/net/unix/garbage.c +++ b/net/unix/garbage.c @@ -282,6 +282,8 @@ void unix_update_edges(struct unix_sock *receiver) } } +static void wait_for_unix_gc(struct scm_fp_list *fpl); + int unix_prepare_fpl(struct scm_fp_list *fpl) { struct unix_vertex *vertex; @@ -303,6 +305,8 @@ int unix_prepare_fpl(struct scm_fp_list *fpl) if (!fpl->edges) goto err; + wait_for_unix_gc(fpl); + return 0; err: @@ -628,7 +632,7 @@ void unix_schedule_gc(void) #define UNIX_INFLIGHT_TRIGGER_GC 16000 #define UNIX_INFLIGHT_SANE_USER (SCM_MAX_FD * 8) -void wait_for_unix_gc(struct scm_fp_list *fpl) +static void wait_for_unix_gc(struct scm_fp_list *fpl) { /* If number of inflight sockets is insane, * force a garbage collect right now. @@ -642,8 +646,7 @@ void wait_for_unix_gc(struct scm_fp_list *fpl) /* Penalise users who want to send AF_UNIX sockets * but whose sockets have not been received yet. */ - if (!fpl || !fpl->count_unix || - READ_ONCE(fpl->user->unix_inflight) < UNIX_INFLIGHT_SANE_USER) + if (READ_ONCE(fpl->user->unix_inflight) < UNIX_INFLIGHT_SANE_USER) return; if (READ_ONCE(gc_in_progress)) |