netdev - [PATCH v5 net-next 4/9] tcp: Restrict SO

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Message-ID: <20250519205820.66184-5-kuniyu@amazon.com>
Date: Mon, 19 May 2025 13:57:55 -0700
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Willem de Bruijn <willemb@...gle.com>
CC: Simon Horman <horms@...nel.org>, Christian Brauner <brauner@...nel.org>,
	Kuniyuki Iwashima <kuniyu@...zon.com>, Kuniyuki Iwashima
	<kuni1840@...il.com>, <netdev@...r.kernel.org>
Subject: [PATCH v5 net-next 4/9] tcp: Restrict SO_TXREHASH to TCP socket.

sk->sk_txrehash is only used for TCP.

Let's restrict SO_TXREHASH to TCP to reflect this.

Later, we will make sk_txrehash a part of the union for other
protocol families.

Note that we need to modify BPF selftest not to get/set
SO_TEREHASH for non-TCP sockets.

Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
Reviewed-by: Willem de Bruijn <willemb@...gle.com>
---
v5: Modify BPF selftest not to set SO_TEREHASH for UDP socket
v3: Return -EOPNOTSUPP for getsockopt() too
---
 net/core/sock.c                                    |  5 +++++
 tools/testing/selftests/bpf/progs/setget_sockopt.c | 11 +++++++++++
 2 files changed, 16 insertions(+)

diff --git a/net/core/sock.c b/net/core/sock.c
index 347ce75482f5..d7d6d3a8efe5 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1276,6 +1276,8 @@ int sk_setsockopt(struct sock *sk, int level, int optname,
 		return 0;
 		}
 	case SO_TXREHASH:
+		if (!sk_is_tcp(sk))
+			return -EOPNOTSUPP;
 		if (val < -1 || val > 1)
 			return -EINVAL;
 		if ((u8)val == SOCK_TXREHASH_DEFAULT)
@@ -2102,6 +2104,9 @@ int sk_getsockopt(struct sock *sk, int level, int optname,
 		break;
 
 	case SO_TXREHASH:
+		if (!sk_is_tcp(sk))
+			return -EOPNOTSUPP;
+
 		/* Paired with WRITE_ONCE() in sk_setsockopt() */
 		v.val = READ_ONCE(sk->sk_txrehash);
 		break;
diff --git a/tools/testing/selftests/bpf/progs/setget_sockopt.c b/tools/testing/selftests/bpf/progs/setget_sockopt.c
index 0107a24b7522..d330b1511979 100644
--- a/tools/testing/selftests/bpf/progs/setget_sockopt.c
+++ b/tools/testing/selftests/bpf/progs/setget_sockopt.c
@@ -83,6 +83,14 @@ struct loop_ctx {
 	struct sock *sk;
 };
 
+static bool sk_is_tcp(struct sock *sk)
+{
+	return (sk->__sk_common.skc_family == AF_INET ||
+		sk->__sk_common.skc_family == AF_INET6) &&
+		sk->sk_type == SOCK_STREAM &&
+		sk->sk_protocol == IPPROTO_TCP;
+}
+
 static int bpf_test_sockopt_flip(void *ctx, struct sock *sk,
 				 const struct sockopt_test *t,
 				 int level)
@@ -91,6 +99,9 @@ static int bpf_test_sockopt_flip(void *ctx, struct sock *sk,
 
 	opt = t->opt;
 
+	if (opt == SO_TXREHASH && !sk_is_tcp(sk))
+		return 0;
+
 	if (bpf_getsockopt(ctx, level, opt, &old, sizeof(old)))
 		return 1;
 	/* kernel initialized txrehash to 255 */
-- 
2.49.0