diff options
| author | Allison Henderson <achender@kernel.org> | 2026-10-19 17:28:15 -0700 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-10-23 15:16:44 -0700 |
| commit | b7dfff5e3eb3984d42026a6d653ec2a3d5cec729 (patch) | |
| tree | 498ea0f9b0a99fd03f8a39d7b530efeff6dfddfc /net/rds | |
| parent | 520631554a689d2cd52452578f3140f045730ee0 (diff) | |
net/rds: include the scope id in the sendmsg connection cache check
rds_sendmsg() reuses the connection cached in rs->rs_conn when its
peer address and ToS match the request. The interface index is part
of a connection's identity as well: rds_conn_create_outgoing() passes
the request's scope_id down as dev_if, and rds_conn_lookup() compares
c_dev_if, so sends to the same link-local address through two
interfaces are two different connections. The cache-hit test never
looked at it.
A socket bound to a non-link-local address has rs_bound_scope_id 0,
and the scope check at the top of rds_sendmsg() accepts any non-zero
destination scope for such a socket. So after a send to fe80::x%ifA,
a send to fe80::x%ifB hits the cached ifA connection and the datagram
leaves through ifA, to whichever peer answers to that address there.
Compare c_dev_if with the request's scope_id in the cache test, so
that such a send takes the lookup path and finds, or creates, the ifB
connection - the same key the lookup uses. A send without a
destination takes its scope from the socket, and the connection it
created was keyed on that same scope, so the comparison holds for it
too; the next patch gives that send the connected peer's own scope.
Found by inspection while reworking this cache for the connection
lifetime series on net-next; not observed in the field.
Fixes: 1e2b44e78eea ("rds: Enable RDS IPv6 support")
Signed-off-by: Allison Henderson <achender@kernel.org>
Link: https://patch.msgid.link/20261020002816.3087414-2-achender@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/rds')
| -rw-r--r-- | net/rds/send.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/net/rds/send.c b/net/rds/send.c index 1afa981e5c06..38b9cc9e0d20 100644 --- a/net/rds/send.c +++ b/net/rds/send.c @@ -1342,7 +1342,8 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len) /* rds_conn_create has a spinlock that runs with IRQ off. * Caching the conn in the socket helps a lot. */ if (rs->rs_conn && ipv6_addr_equal(&rs->rs_conn->c_faddr, &daddr) && - rs->rs_tos == rs->rs_conn->c_tos) { + rs->rs_tos == rs->rs_conn->c_tos && + rs->rs_conn->c_dev_if == scope_id) { conn = rs->rs_conn; } else { conn = rds_conn_create_outgoing(sock_net(sock->sk), |