From 2e82a58d6c0797092eabe7ba66a532c11548047f Mon Sep 17 00:00:00 2001 From: Vincent Duvert Date: Sun, 5 May 2024 11:54:57 -0700 Subject: [PATCH] appletalk: Improve handling of broadcast packets When a broadcast AppleTalk packet is received, prefer queuing it on the socket whose address matches the address of the interface that received the packet (and is listening on the correct port). Userspace applications that handle such packets will usually send a response on the same socket that received the packet; this fix allows the response to be sent on the correct interface. If a socket matching the interface's address is not found, an arbitrary socket listening on the correct port will be used, if any. This matches the implementation's previous behavior. Fixes atalkd's responses to network information requests when multiple network interfaces are configured to use AppleTalk. Link: https://lore.kernel.org/netdev/20200722113752.1218-2-vincent.ldev@duvert.net/ Link: https://gist.github.com/VinDuv/4db433b6dce39d51a5b7847ee749b2a4 Signed-off-by: Vincent Duvert Signed-off-by: Doug Brown Signed-off-by: David S. Miller --- net/appletalk/ddp.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/net/appletalk/ddp.c b/net/appletalk/ddp.c index 198f5ba2feae..b068651984fe 100644 --- a/net/appletalk/ddp.c +++ b/net/appletalk/ddp.c @@ -88,6 +88,7 @@ static inline void atalk_remove_socket(struct sock *sk) static struct sock *atalk_search_socket(struct sockaddr_at *to, struct atalk_iface *atif) { + struct sock *def_socket = NULL; struct sock *s; read_lock_bh(&atalk_sockets_lock); @@ -98,8 +99,20 @@ static struct sock *atalk_search_socket(struct sockaddr_at *to, continue; if (to->sat_addr.s_net == ATADDR_ANYNET && - to->sat_addr.s_node == ATADDR_BCAST) - goto found; + to->sat_addr.s_node == ATADDR_BCAST) { + if (atif->address.s_node == at->src_node && + atif->address.s_net == at->src_net) { + /* This socket's address matches the address of the interface + * that received the packet -- use it + */ + goto found; + } + + /* Continue searching for a socket matching the interface address, + * but use this socket by default if no other one is found + */ + def_socket = s; + } if (to->sat_addr.s_net == at->src_net && (to->sat_addr.s_node == at->src_node || @@ -116,7 +129,7 @@ static struct sock *atalk_search_socket(struct sockaddr_at *to, goto found; } } - s = NULL; + s = def_socket; found: read_unlock_bh(&atalk_sockets_lock); return s;