diff options
| author | Kuniyuki Iwashima <kuniyu@amazon.com> | 2025-05-21 14:45:17 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-06-04 14:42:22 +0200 |
| commit | d2d9f382e2db634f9d499e749c668f631ea76e10 (patch) | |
| tree | 71642251628df7d1d525f4dcf675d80f51c33cb1 /net/unix/af_unix.c | |
| parent | 4fc7df1c6da14aef3ad9d2ea39565c020ec09aaa (diff) | |
af_unix: Link struct unix_edge when queuing skb.
commit 42f298c06b30bfe0a8cbee5d38644e618699e26e upstream.
Just before queuing skb with inflight fds, we call scm_stat_add(),
which is a good place to set up the preallocated struct unix_vertex
and struct unix_edge in UNIXCB(skb).fp.
Then, we call unix_add_edges() and construct the directed graph
as follows:
1. Set the inflight socket's unix_sock to unix_edge.predecessor.
2. Set the receiver's unix_sock to unix_edge.successor.
3. Set the preallocated vertex to inflight socket's unix_sock.vertex.
4. Link inflight socket's unix_vertex.entry to unix_unvisited_vertices.
5. Link unix_edge.vertex_entry to the inflight socket's unix_vertex.edges.
Let's say we pass the fd of AF_UNIX socket A to B and the fd of B
to C. The graph looks like this:
+-------------------------+
| unix_unvisited_vertices | <-------------------------.
+-------------------------+ |
+ |
| +--------------+ +--------------+ | +--------------+
| | unix_sock A | <---. .---> | unix_sock B | <-|-. .---> | unix_sock C |
| +--------------+ | | +--------------+ | | | +--------------+
| .-+ | vertex | | | .-+ | vertex | | | | | vertex |
| | +--------------+ | | | +--------------+ | | | +--------------+
| | | | | | | |
| | +--------------+ | | | +--------------+ | | |
| '-> | unix_vertex | | | '-> | unix_vertex | | | |
| +--------------+ | | +--------------+ | | |
`---> | entry | +---------> | entry | +-' | |
|--------------| | | |--------------| | |
| edges | <-. | | | edges | <-. | |
+--------------+ | | | +--------------+ | | |
| | | | | |
.----------------------' | | .----------------------' | |
| | | | | |
| +--------------+ | | | +--------------+ | |
| | unix_edge | | | | | unix_edge | | |
| +--------------+ | | | +--------------+ | |
`-> | vertex_entry | | | `-> | vertex_entry | | |
|--------------| | | |--------------| | |
| predecessor | +---' | | predecessor | +---' |
|--------------| | |--------------| |
| successor | +-----' | successor | +-----'
+--------------+ +--------------+
Henceforth, we denote such a graph as A -> B (-> C).
Now, we can express all inflight fd graphs that do not contain
embryo sockets. We will support the particular case later.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20240325202425.60930-4-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/unix/af_unix.c')
| -rw-r--r-- | net/unix/af_unix.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 6d62fa5b0e68..e54f54f9d994 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1920,8 +1920,10 @@ static void scm_stat_add(struct sock *sk, struct sk_buff *skb) struct scm_fp_list *fp = UNIXCB(skb).fp; struct unix_sock *u = unix_sk(sk); - if (unlikely(fp && fp->count)) + if (unlikely(fp && fp->count)) { atomic_add(fp->count, &u->scm_stat.nr_fds); + unix_add_edges(fp, u); + } } static void scm_stat_del(struct sock *sk, struct sk_buff *skb) @@ -1929,8 +1931,10 @@ static void scm_stat_del(struct sock *sk, struct sk_buff *skb) struct scm_fp_list *fp = UNIXCB(skb).fp; struct unix_sock *u = unix_sk(sk); - if (unlikely(fp && fp->count)) + if (unlikely(fp && fp->count)) { atomic_sub(fp->count, &u->scm_stat.nr_fds); + unix_del_edges(fp); + } } /* |