net/tcp: Wire TCP-AO to request sockets

Now when the new request socket is created from the listening socket,
it's recorded what MKT was used by the peer. tcp_rsk_used_ao() is
a new helper for checking if TCP-AO option was used to create the
request socket.
tcp_ao_copy_all_matching() will copy all keys that match the peer on the
request socket, as well as preparing them for the usage (creating
traffic keys).

Co-developed-by: Francesco Ruggeri <fruggeri@arista.com>
Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
Co-developed-by: Salam Noureddine <noureddine@arista.com>
Signed-off-by: Salam Noureddine <noureddine@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Acked-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 250 insertions, 14 deletions

diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index 7c4e2f42845a..68d81704e14e 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -169,6 +169,23 @@ static void tcp_ao_link_mkt(struct tcp_ao_info *ao, struct tcp_ao_key *mkt)
 	hlist_add_head_rcu(&mkt->node, &ao->head);
 }
 
+static struct tcp_ao_key *tcp_ao_copy_key(struct sock *sk,
+					  struct tcp_ao_key *key)
+{
+	struct tcp_ao_key *new_key;
+
+	new_key = sock_kmalloc(sk, tcp_ao_sizeof_key(key),
+			       GFP_ATOMIC);
+	if (!new_key)
+		return NULL;
+
+	*new_key = *key;
+	INIT_HLIST_NODE(&new_key->node);
+	tcp_sigpool_get(new_key->tcp_sigpool_id);
+
+	return new_key;
+}
+
 static void tcp_ao_key_free_rcu(struct rcu_head *head)
 {
 	struct tcp_ao_key *key = container_of(head, struct tcp_ao_key, rcu);
@@ -290,6 +307,42 @@ static int tcp_ao_calc_key_sk(struct tcp_ao_key *mkt, u8 *key,
 		return -EOPNOTSUPP;
 }
 
+int tcp_v4_ao_calc_key_rsk(struct tcp_ao_key *mkt, u8 *key,
+			   struct request_sock *req)
+{
+	struct inet_request_sock *ireq = inet_rsk(req);
+
+	return tcp_v4_ao_calc_key(mkt, key,
+				  ireq->ir_loc_addr, ireq->ir_rmt_addr,
+				  htons(ireq->ir_num), ireq->ir_rmt_port,
+				  htonl(tcp_rsk(req)->snt_isn),
+				  htonl(tcp_rsk(req)->rcv_isn));
+}
+
+static int tcp_v4_ao_calc_key_skb(struct tcp_ao_key *mkt, u8 *key,
+				  const struct sk_buff *skb,
+				  __be32 sisn, __be32 disn)
+{
+	const struct iphdr *iph = ip_hdr(skb);
+	const struct tcphdr *th = tcp_hdr(skb);
+
+	return tcp_v4_ao_calc_key(mkt, key, iph->saddr, iph->daddr,
+				  th->source, th->dest, sisn, disn);
+}
+
+static int tcp_ao_calc_key_skb(struct tcp_ao_key *mkt, u8 *key,
+			       const struct sk_buff *skb,
+			       __be32 sisn, __be32 disn, int family)
+{
+	if (family == AF_INET)
+		return tcp_v4_ao_calc_key_skb(mkt, key, skb, sisn, disn);
+#if IS_ENABLED(CONFIG_IPV6)
+	else if (family == AF_INET6)
+		return tcp_v6_ao_calc_key_skb(mkt, key, skb, sisn, disn);
+#endif
+	return -EAFNOSUPPORT;
+}
+
 static int tcp_v4_ao_hash_pseudoheader(struct tcp_sigpool *hp,
 				       __be32 daddr, __be32 saddr,
 				       int nbytes)
@@ -515,6 +568,16 @@ int tcp_v4_ao_hash_skb(char *ao_hash, struct tcp_ao_key *key,
 			       tkey, hash_offset, sne);
 }
 
+struct tcp_ao_key *tcp_v4_ao_lookup_rsk(const struct sock *sk,
+					struct request_sock *req,
+					int sndid, int rcvid)
+{
+	union tcp_ao_addr *addr =
+			(union tcp_ao_addr *)&inet_rsk(req)->ir_rmt_addr;
+
+	return tcp_ao_do_lookup(sk, addr, AF_INET, sndid, rcvid);
+}
+
 struct tcp_ao_key *tcp_v4_ao_lookup(const struct sock *sk, struct sock *addr_sk,
 				    int sndid, int rcvid)
 {
@@ -528,7 +591,7 @@ int tcp_ao_prepare_reset(const struct sock *sk, struct sk_buff *skb,
 			 struct tcp_ao_key **key, char **traffic_key,
 			 bool *allocated_traffic_key, u8 *keyid, u32 *sne)
 {
-	struct tcp_ao_key *rnext_key;
+	const struct tcphdr *th = tcp_hdr(skb);
 	struct tcp_ao_info *ao_info;
 
 	*allocated_traffic_key = false;
@@ -543,23 +606,62 @@ int tcp_ao_prepare_reset(const struct sock *sk, struct sk_buff *skb,
 		return -ENOTCONN;
 
 	if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_NEW_SYN_RECV)) {
-		return -1;
+		unsigned int family = READ_ONCE(sk->sk_family);
+		union tcp_ao_addr *addr;
+		__be32 disn, sisn;
 
-	if (sk->sk_state == TCP_TIME_WAIT)
-		ao_info = rcu_dereference(tcp_twsk(sk)->ao_info);
-	else
+		if (sk->sk_state == TCP_NEW_SYN_RECV) {
+			struct request_sock *req = inet_reqsk(sk);
+
+			sisn = htonl(tcp_rsk(req)->rcv_isn);
+			disn = htonl(tcp_rsk(req)->snt_isn);
+			*sne = 0;
+		} else {
+			sisn = th->seq;
+			disn = 0;
+		}
+		if (IS_ENABLED(CONFIG_IPV6) && family == AF_INET6)
+			addr = (union tcp_md5_addr *)&ipv6_hdr(skb)->saddr;
+		else
+			addr = (union tcp_md5_addr *)&ip_hdr(skb)->saddr;
+#if IS_ENABLED(CONFIG_IPV6)
+		if (family == AF_INET6 && ipv6_addr_v4mapped(&sk->sk_v6_daddr))
+			family = AF_INET;
+#endif
+
+		sk = sk_const_to_full_sk(sk);
 		ao_info = rcu_dereference(tcp_sk(sk)->ao_info);
-	if (!ao_info)
-		return -ENOENT;
+		if (!ao_info)
+			return -ENOENT;
+		*key = tcp_ao_do_lookup(sk, addr, family, -1, aoh->rnext_keyid);
+		if (!*key)
+			return -ENOENT;
+		*traffic_key = kmalloc(tcp_ao_digest_size(*key), GFP_ATOMIC);
+		if (!*traffic_key)
+			return -ENOMEM;
+		*allocated_traffic_key = true;
+		if (tcp_ao_calc_key_skb(*key, *traffic_key, skb,
+					sisn, disn, family))
+			return -1;
+		*keyid = (*key)->rcvid;
+	} else {
+		struct tcp_ao_key *rnext_key;
 
-	*key = tcp_ao_established_key(ao_info, aoh->rnext_keyid, -1);
-	if (!*key)
-		return -ENOENT;
-	*traffic_key = snd_other_key(*key);
-	rnext_key = READ_ONCE(ao_info->rnext_key);
-	*keyid = rnext_key->rcvid;
-	*sne = 0;
+		if (sk->sk_state == TCP_TIME_WAIT)
+			ao_info = rcu_dereference(tcp_twsk(sk)->ao_info);
+		else
+			ao_info = rcu_dereference(tcp_sk(sk)->ao_info);
+		if (!ao_info)
+			return -ENOENT;
 
+		*key = tcp_ao_established_key(ao_info, aoh->rnext_keyid, -1);
+		if (!*key)
+			return -ENOENT;
+		*traffic_key = snd_other_key(*key);
+		rnext_key = READ_ONCE(ao_info->rnext_key);
+		*keyid = rnext_key->rcvid;
+		*sne = 0;
+	}
 	return 0;
 }
 
@@ -597,6 +699,46 @@ int tcp_ao_transmit_skb(struct sock *sk, struct sk_buff *skb,
 	return 0;
 }
 
+static struct tcp_ao_key *tcp_ao_inbound_lookup(unsigned short int family,
+		const struct sock *sk, const struct sk_buff *skb,
+		int sndid, int rcvid)
+{
+	if (family == AF_INET) {
+		const struct iphdr *iph = ip_hdr(skb);
+
+		return tcp_ao_do_lookup(sk, (union tcp_ao_addr *)&iph->saddr,
+				AF_INET, sndid, rcvid);
+	} else {
+		const struct ipv6hdr *iph = ipv6_hdr(skb);
+
+		return tcp_ao_do_lookup(sk, (union tcp_ao_addr *)&iph->saddr,
+				AF_INET6, sndid, rcvid);
+	}
+}
+
+void tcp_ao_syncookie(struct sock *sk, const struct sk_buff *skb,
+		      struct tcp_request_sock *treq,
+		      unsigned short int family)
+{
+	const struct tcphdr *th = tcp_hdr(skb);
+	const struct tcp_ao_hdr *aoh;
+	struct tcp_ao_key *key;
+
+	treq->maclen = 0;
+
+	if (tcp_parse_auth_options(th, NULL, &aoh) || !aoh)
+		return;
+
+	key = tcp_ao_inbound_lookup(family, sk, skb, -1, aoh->keyid);
+	if (!key)
+		/* Key not found, continue without TCP-AO */
+		return;
+
+	treq->ao_rcv_next = aoh->keyid;
+	treq->ao_keyid = aoh->rnext_keyid;
+	treq->maclen = tcp_ao_maclen(key);
+}
+
 static int tcp_ao_cache_traffic_keys(const struct sock *sk,
 				     struct tcp_ao_info *ao,
 				     struct tcp_ao_key *ao_key)
@@ -704,6 +846,100 @@ void tcp_ao_finish_connect(struct sock *sk, struct sk_buff *skb)
 		tcp_ao_cache_traffic_keys(sk, ao, key);
 }
 
+int tcp_ao_copy_all_matching(const struct sock *sk, struct sock *newsk,
+			     struct request_sock *req, struct sk_buff *skb,
+			     int family)
+{
+	struct tcp_ao_key *key, *new_key, *first_key;
+	struct tcp_ao_info *new_ao, *ao;
+	struct hlist_node *key_head;
+	union tcp_ao_addr *addr;
+	bool match = false;
+	int ret = -ENOMEM;
+
+	ao = rcu_dereference(tcp_sk(sk)->ao_info);
+	if (!ao)
+		return 0;
+
+	/* New socket without TCP-AO on it */
+	if (!tcp_rsk_used_ao(req))
+		return 0;
+
+	new_ao = tcp_ao_alloc_info(GFP_ATOMIC);
+	if (!new_ao)
+		return -ENOMEM;
+	new_ao->lisn = htonl(tcp_rsk(req)->snt_isn);
+	new_ao->risn = htonl(tcp_rsk(req)->rcv_isn);
+	new_ao->ao_required = ao->ao_required;
+
+	if (family == AF_INET) {
+		addr = (union tcp_ao_addr *)&newsk->sk_daddr;
+#if IS_ENABLED(CONFIG_IPV6)
+	} else if (family == AF_INET6) {
+		addr = (union tcp_ao_addr *)&newsk->sk_v6_daddr;
+#endif
+	} else {
+		ret = -EAFNOSUPPORT;
+		goto free_ao;
+	}
+
+	hlist_for_each_entry_rcu(key, &ao->head, node) {
+		if (tcp_ao_key_cmp(key, addr, key->prefixlen, family, -1, -1))
+			continue;
+
+		new_key = tcp_ao_copy_key(newsk, key);
+		if (!new_key)
+			goto free_and_exit;
+
+		tcp_ao_cache_traffic_keys(newsk, new_ao, new_key);
+		tcp_ao_link_mkt(new_ao, new_key);
+		match = true;
+	}
+
+	if (!match) {
+		/* RFC5925 (7.4.1) specifies that the TCP-AO status
+		 * of a connection is determined on the initial SYN.
+		 * At this point the connection was TCP-AO enabled, so
+		 * it can't switch to being unsigned if peer's key
+		 * disappears on the listening socket.
+		 */
+		ret = -EKEYREJECTED;
+		goto free_and_exit;
+	}
+
+	key_head = rcu_dereference(hlist_first_rcu(&new_ao->head));
+	first_key = hlist_entry_safe(key_head, struct tcp_ao_key, node);
+
+	key = tcp_ao_established_key(new_ao, tcp_rsk(req)->ao_keyid, -1);
+	if (key)
+		new_ao->current_key = key;
+	else
+		new_ao->current_key = first_key;
+
+	/* set rnext_key */
+	key = tcp_ao_established_key(new_ao, -1, tcp_rsk(req)->ao_rcv_next);
+	if (key)
+		new_ao->rnext_key = key;
+	else
+		new_ao->rnext_key = first_key;
+
+	sk_gso_disable(newsk);
+	rcu_assign_pointer(tcp_sk(newsk)->ao_info, new_ao);
+
+	return 0;
+
+free_and_exit:
+	hlist_for_each_entry_safe(key, key_head, &new_ao->head, node) {
+		hlist_del(&key->node);
+		tcp_sigpool_release(key->tcp_sigpool_id);
+		atomic_sub(tcp_ao_sizeof_key(key), &newsk->sk_omem_alloc);
+		kfree_sensitive(key);
+	}
+free_ao:
+	kfree(new_ao);
+	return ret;
+}
+
 static bool tcp_ao_can_set_current_rnext(struct sock *sk)
 {
 	/* There aren't current/rnext keys on TCP_LISTEN sockets */