[PATCH 10/19] tcp: ipv6: Add AO signing for tcp_v6_send_response

Leonard Crestez
2021-09-21T16:17:44Z

This is a special code path for acks and resets outside of normal
connection establishment and closing.

Signed-off-by: Leonard Crestez <cdleonard@gmail.com>
---
net/ipv6/tcp_ipv6.c | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 724145ddf122..d922219af20e 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -896,13 +896,37 @@ static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32
struct sock *ctl_sk = net->ipv6.tcp_sk;
unsigned int tot_len = sizeof(struct tcphdr);
__be32 mrst = 0, *topt;
struct dst_entry *dst;
__u32 mark = 0;
+#ifdef CONFIG_TCP_AUTHOPT
+ struct tcp_authopt_info *authopt_info = NULL;
+ struct tcp_authopt_key_info *authopt_key_info = NULL;
+ u8 authopt_rnextkeyid;
+#endif

if (tsecr)
tot_len += TCPOLEN_TSTAMP_ALIGNED;
+#ifdef CONFIG_TCP_AUTHOPT
+ /* Key lookup before SKB allocation */
+ if (static_branch_unlikely(&tcp_authopt_needed) && sk)
+ {
+ if (sk->sk_state == TCP_TIME_WAIT)
+ authopt_info = tcp_twsk(sk)->tw_authopt_info;
+ else
+ authopt_info = rcu_dereference(tcp_sk(sk)->authopt_info);
+
+ if (authopt_info) {
+ authopt_key_info = __tcp_authopt_select_key(sk, authopt_info, sk, &authopt_rnextkeyid);
+ if (authopt_key_info) {
+ tot_len += TCPOLEN_AUTHOPT_OUTPUT;
+ /* Don't use MD5 */
+ key = NULL;
+ }
+ }
+ }
+#endif
#ifdef CONFIG_TCP_MD5SIG
if (key)
tot_len += TCPOLEN_MD5SIG_ALIGNED;
#endif

@@ -955,10 +979,21 @@ static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32
tcp_v6_md5_hash_hdr((__u8 *)topt, key,
&ipv6_hdr(skb)->saddr,
&ipv6_hdr(skb)->daddr, t1);
}
#endif
+#ifdef CONFIG_TCP_AUTHOPT
+ /* Compute the TCP-AO mac. Unlike in the ipv4 case we have a real SKB */
+ if (static_branch_unlikely(&tcp_authopt_needed) && authopt_key_info)
+ {
+ *topt++ = htonl((TCPOPT_AUTHOPT << 24) |
+ (TCPOLEN_AUTHOPT_OUTPUT << 16) |
+ (authopt_key_info->send_id << 8) |
+ (authopt_rnextkeyid));
+ tcp_authopt_hash((char*)topt, authopt_key_info, (struct sock*)sk, buff);
+ }
+#endif

memset(&fl6, 0, sizeof(fl6));
fl6.daddr = ipv6_hdr(skb)->saddr;
fl6.saddr = ipv6_hdr(skb)->daddr;
fl6.flowlabel = label;
--
2.25.1