netdev - [PATCH v8 18/26] tcp: authopt: Add v4mapped ipv6 address support

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Date:   Mon,  5 Sep 2022 10:05:54 +0300
From:   Leonard Crestez <cdleonard@...il.com>
To:     David Ahern <dsahern@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Dmitry Safonov <0x7f454c46@...il.com>
Cc:     Francesco Ruggeri <fruggeri@...sta.com>,
        Salam Noureddine <noureddine@...sta.com>,
        Philip Paeps <philip@...uble.is>,
        Shuah Khan <shuah@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Kuniyuki Iwashima <kuniyu@...zon.co.jp>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Yuchung Cheng <ycheng@...gle.com>,
        Mat Martineau <mathew.j.martineau@...ux.intel.com>,
        Christoph Paasch <cpaasch@...le.com>,
        Ivan Delalande <colona@...sta.com>,
        Caowangbao <caowangbao@...wei.com>,
        Priyaranjan Jha <priyarjha@...gle.com>, netdev@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v8 18/26] tcp: authopt: Add v4mapped ipv6 address support

Keys that are added with v4mapped ipv6 addresses will now be used for
ipv4 packets. This outward behavior is similar to how MD5 support
currently works.

The implementation is different - v4mapped keys are still stored with
ipv6 addresses.

Signed-off-by: Leonard Crestez <cdleonard@...il.com>
---
 net/ipv4/tcp_authopt.c | 35 +++++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/net/ipv4/tcp_authopt.c b/net/ipv4/tcp_authopt.c
index 6db06e1edcc7..28c10a916fb3 100644
--- a/net/ipv4/tcp_authopt.c
+++ b/net/ipv4/tcp_authopt.c
@@ -324,27 +324,30 @@ static bool tcp_authopt_key_match_skb_addr(struct tcp_authopt_key_info *key,
 		struct sockaddr_in6 *key_addr = (struct sockaddr_in6 *)&key->addr;
 
 		return ipv6_prefix_equal(&ip6h->saddr,
 					 &key_addr->sin6_addr,
 					 key->prefixlen);
+	} else if (keyaf == AF_INET6 && iph->version == 4) {
+		struct sockaddr_in6 *key_addr = (struct sockaddr_in6 *)&key->addr;
+
+		/* handle ipv6-mapped-ipv4-addresses */
+		if (ipv6_addr_v4mapped(&key_addr->sin6_addr)) {
+			__be32 mask = inet_make_mask(key->prefixlen);
+			__be32 ipv4 = key_addr->sin6_addr.s6_addr32[3];
+
+			return (ipv4 & mask) == ipv4;
+		}
 	}
 
-	/* This actually happens with ipv6-mapped-ipv4-addresses
-	 * IPv6 listen sockets will be asked to validate ipv4 packets.
-	 */
 	return false;
 }
 
 static bool tcp_authopt_key_match_sk_addr(struct tcp_authopt_key_info *key,
 					  const struct sock *addr_sk)
 {
 	u16 keyaf = key->addr.ss_family;
 
-	/* This probably can't happen even with ipv4-mapped-ipv6 */
-	if (keyaf != addr_sk->sk_family)
-		return false;
-
 	if (keyaf == AF_INET) {
 		struct sockaddr_in *key_addr = (struct sockaddr_in *)&key->addr;
 		__be32 mask = inet_make_mask(key->prefixlen);
 
 		return (addr_sk->sk_daddr & mask) == key_addr->sin_addr.s_addr;
@@ -353,10 +356,16 @@ static bool tcp_authopt_key_match_sk_addr(struct tcp_authopt_key_info *key,
 		struct sockaddr_in6 *key_addr = (struct sockaddr_in6 *)&key->addr;
 
 		return ipv6_prefix_equal(&addr_sk->sk_v6_daddr,
 					 &key_addr->sin6_addr,
 					 key->prefixlen);
+	} else if (keyaf == AF_INET6 && addr_sk->sk_family == AF_INET) {
+		struct sockaddr_in6 *key_addr = (struct sockaddr_in6 *)&key->addr;
+		__be32 mask = inet_make_mask(key->prefixlen);
+		__be32 ipv4 = key_addr->sin6_addr.s6_addr32[3];
+
+		return (addr_sk->sk_daddr & mask) == ipv4;
 #endif
 	}
 
 	return false;
 }
@@ -1475,14 +1484,20 @@ static int __tcp_authopt_calc_mac(struct sock *sk,
 				  char *macbuf)
 {
 	struct tcp_authopt_alg_pool *mac_pool;
 	u8 traffic_key[TCP_AUTHOPT_MAX_TRAFFIC_KEY_LEN];
 	int err;
-	bool ipv6 = (sk->sk_family != AF_INET);
+	bool ipv6;
 
-	if (sk->sk_family != AF_INET && sk->sk_family != AF_INET6)
-		return -EINVAL;
+#if IS_ENABLED(CONFIG_IPV6)
+	if (input)
+		ipv6 = (skb->protocol == htons(ETH_P_IPV6));
+	else
+		ipv6 = (sk->sk_family == AF_INET6) && !ipv6_addr_v4mapped(&sk->sk_v6_daddr);
+#else
+	ipv6 = false;
+#endif
 
 	err = tcp_authopt_get_traffic_key(sk, skb, key, info, input, ipv6, traffic_key);
 	if (err)
 		return err;
 
-- 
2.25.1