Subject: [PATCH] net: error on unsupported IP setsockopts in IPv6

From: Richard Gobert <[email-masked]>
Date: Thu, 9 Jun 2022 17:26:10 +0200

The IP_TTL and IP_TOS sockopts are unsupported for IPv6 sockets,
this bug was reported previously to the kernel bugzilla [1].
Make the IP_TTL and IP_TOS sockopts return an error for AF_INET6 sockets.

[1] https://bugzilla.kernel.org/show_bug.cgi?id=212585

Signed-off-by: Richard Gobert <[email-masked]>
---
 net/ipv6/ipv6_sockglue.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 222f6bf220ba..2cdaa8f3a8f2 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -1012,8 +1012,16 @@ int ipv6_setsockopt(struct sock *sk, int level, int optname, sockptr_t optval,
 {
 	int err;
 
-	if (level == SOL_IP && sk->sk_type != SOCK_RAW)
-		return udp_prot.setsockopt(sk, level, optname, optval, optlen);
+	if (level == SOL_IP && sk->sk_type != SOCK_RAW) {
+		switch (optname) {
+		/* Some IP opts are not supported for IPv6 sockets */
+		case IP_TTL:
+		case IP_TOS:
+			return -ENOPROTOOPT;
+		default:
+			return udp_prot.setsockopt(sk, level, optname, optval, optlen);
+		}
+	}
 
 	if (level != SOL_IPV6)
 		return -ENOPROTOOPT;
-- 
2.36.1