net: annotate races around sk->sk_uid

sk->sk_uid can be read while another thread changes its
value in sockfs_setattr().

Add sk_uid(const struct sock *sk) helper to factorize the needed
READ_ONCE() annotations, and add corresponding WRITE_ONCE()
where needed.

Fixes: 86741ec25462 ("net: core: Add a UID field to struct sock.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Lorenzo Colitti <lorenzo@google.com>
Reviewed-by: Maciej Żenczykowski <maze@google.com>
Link: https://patch.msgid.link/20250620133001.4090592-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

6 files changed, 10 insertions, 7 deletions

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 6906bedad19a..46750c96d08e 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -812,7 +812,7 @@ struct dst_entry *inet_csk_route_req(const struct sock *sk,
 			   sk->sk_protocol, inet_sk_flowi_flags(sk),
 			   (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 			   ireq->ir_loc_addr, ireq->ir_rmt_port,
-			   htons(ireq->ir_num), sk->sk_uid);
+			   htons(ireq->ir_num), sk_uid(sk));
 	security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
 	rt = ip_route_output_flow(net, fl4, sk);
 	if (IS_ERR(rt))
@@ -849,7 +849,7 @@ struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
 			   sk->sk_protocol, inet_sk_flowi_flags(sk),
 			   (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 			   ireq->ir_loc_addr, ireq->ir_rmt_port,
-			   htons(ireq->ir_num), sk->sk_uid);
+			   htons(ireq->ir_num), sk_uid(sk));
 	security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
 	rt = ip_route_output_flow(net, fl4, sk);
 	if (IS_ERR(rt))
diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index c14baa6589c7..4eacaf00e2e9 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -781,7 +781,7 @@ static int ping_v4_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	flowi4_init_output(&fl4, ipc.oif, ipc.sockc.mark,
 			   ipc.tos & INET_DSCP_MASK, scope,
 			   sk->sk_protocol, inet_sk_flowi_flags(sk), faddr,
-			   saddr, 0, 0, sk->sk_uid);
+			   saddr, 0, 0, sk_uid(sk));
 
 	fl4.fl4_icmp_type = user_icmph.type;
 	fl4.fl4_icmp_code = user_icmph.code;
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 6aace4d55733..32f942d0f944 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -610,7 +610,7 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 			   hdrincl ? ipc.protocol : sk->sk_protocol,
 			   inet_sk_flowi_flags(sk) |
 			    (hdrincl ? FLOWI_FLAG_KNOWN_NH : 0),
-			   daddr, saddr, 0, 0, sk->sk_uid);
+			   daddr, saddr, 0, 0, sk_uid(sk));
 
 	fl4.fl4_icmp_type = 0;
 	fl4.fl4_icmp_code = 0;
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 3ddf6bf40357..3ff2bd56d050 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -556,7 +556,8 @@ static void build_sk_flow_key(struct flowi4 *fl4, const struct sock *sk)
 			   inet_test_bit(HDRINCL, sk) ?
 				IPPROTO_RAW : sk->sk_protocol,
 			   inet_sk_flowi_flags(sk),
-			   daddr, inet->inet_saddr, 0, 0, sk->sk_uid);
+			   daddr, inet->inet_saddr, 0, 0,
+			   sk_uid(sk));
 	rcu_read_unlock();
 }
 
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 5459a78b9809..eb0819463fae 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -454,7 +454,8 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
 			   ip_sock_rt_tos(sk), ip_sock_rt_scope(sk),
 			   IPPROTO_TCP, inet_sk_flowi_flags(sk),
 			   opt->srr ? opt->faddr : ireq->ir_rmt_addr,
-			   ireq->ir_loc_addr, th->source, th->dest, sk->sk_uid);
+			   ireq->ir_loc_addr, th->source, th->dest,
+			   sk_uid(sk));
 	security_req_classify_flow(req, flowi4_to_flowi_common(&fl4));
 	rt = ip_route_output_key(net, &fl4);
 	if (IS_ERR(rt)) {
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index dde52b8050b8..f94bb222aa2d 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1445,7 +1445,8 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 		flowi4_init_output(fl4, ipc.oif, ipc.sockc.mark,
 				   ipc.tos & INET_DSCP_MASK, scope,
 				   sk->sk_protocol, flow_flags, faddr, saddr,
-				   dport, inet->inet_sport, sk->sk_uid);
+				   dport, inet->inet_sport,
+				   sk_uid(sk));
 
 		security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4));
 		rt = ip_route_output_flow(net, fl4, sk);