netdev - [PATCH bpf-next v2] bpf: Fix bpf_get/setsockopt to tos not take effect when TCP over IPv4 via INET6 API

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Message-Id: <20240823085313.75419-1-zhoufeng.zf@bytedance.com>
Date: Fri, 23 Aug 2024 16:53:13 +0800
From: Feng zhou <zhoufeng.zf@...edance.com>
To: edumazet@...gle.com,
	davem@...emloft.net,
	kuba@...nel.org,
	pabeni@...hat.com,
	ast@...nel.org,
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Cc: netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
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	zhoufeng.zf@...edance.com
Subject: [PATCH bpf-next v2] bpf: Fix bpf_get/setsockopt to tos not take effect when TCP over IPv4 via INET6 API

From: Feng Zhou <zhoufeng.zf@...edance.com>

when TCP over IPv4 via INET6 API, bpf_get/setsockopt with ipv4 will
fail, because sk->sk_family is AF_INET6. With ipv6 will success, not
take effect, because inet_csk(sk)->icsk_af_ops is ipv6_mapped and
use ip_queue_xmit, inet_sk(sk)->tos.

So bpf_get/setsockopt needs add the judgment of this case. Just check
"inet_csk(sk)->icsk_af_ops == &ipv6_mapped".

| Reported-by: kernel test robot <lkp@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202408152034.lw9Ilsj6-lkp@intel.com/
Signed-off-by: Feng Zhou <zhoufeng.zf@...edance.com>
---
Changelog:
v1->v2: Addressed comments from kernel test robot
- Fix compilation error
Details in here:
https://lore.kernel.org/bpf/202408152058.YXAnhLgZ-lkp@intel.com/T/

 include/net/tcp.h   | 2 ++
 net/core/filter.c   | 6 +++++-
 net/ipv6/tcp_ipv6.c | 6 ++++++
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 2aac11e7e1cc..ea673f88c900 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -493,6 +493,8 @@ struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops,
 					    struct tcp_options_received *tcp_opt,
 					    int mss, u32 tsoff);
 
+bool is_tcp_sock_ipv6_mapped(struct sock *sk);
+
 #if IS_ENABLED(CONFIG_BPF)
 struct bpf_tcp_req_attrs {
 	u32 rcv_tsval;
diff --git a/net/core/filter.c b/net/core/filter.c
index ecf2ddf633bf..02a825e35c4d 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5399,7 +5399,11 @@ static int sol_ip_sockopt(struct sock *sk, int optname,
 			  char *optval, int *optlen,
 			  bool getopt)
 {
-	if (sk->sk_family != AF_INET)
+	if (sk->sk_family != AF_INET
+#if IS_BUILTIN(CONFIG_IPV6)
+	    && !is_tcp_sock_ipv6_mapped(sk)
+#endif
+	    )
 		return -EINVAL;
 
 	switch (optname) {
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 200fea92f12f..125c69f1d085 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -92,6 +92,12 @@ static const struct tcp_sock_af_ops tcp_sock_ipv6_mapped_specific;
 #define tcp_inet6_sk(sk) (&container_of_const(tcp_sk(sk), \
 					      struct tcp6_sock, tcp)->inet6)
 
+bool is_tcp_sock_ipv6_mapped(struct sock *sk)
+{
+	return (inet_csk(sk)->icsk_af_ops == &ipv6_mapped);
+}
+EXPORT_SYMBOL_GPL(is_tcp_sock_ipv6_mapped);
+
 static void inet6_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
 {
 	struct dst_entry *dst = skb_dst(skb);
-- 
2.30.2