tcp: add server ip to encrypt cookie in fast open
Encrypt the cookie with both server and client IPv4 addresses, such that multi-homed server will grant different cookies based on both the source and destination IPs. No client change is needed since cookie is opaque to the client. Signed-off-by: Yuchung Cheng <ycheng@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -1300,7 +1300,8 @@ void tcp_free_fastopen_req(struct tcp_sock *tp);
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extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
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int tcp_fastopen_reset_cipher(void *key, unsigned int len);
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void tcp_fastopen_cookie_gen(__be32 addr, struct tcp_fastopen_cookie *foc);
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extern void tcp_fastopen_cookie_gen(__be32 src, __be32 dst,
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struct tcp_fastopen_cookie *foc);
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#define TCP_FASTOPEN_KEY_LENGTH 16
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@ -58,23 +58,22 @@ error: kfree(ctx);
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return err;
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}
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/* Computes the fastopen cookie for the peer.
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* The peer address is a 128 bits long (pad with zeros for IPv4).
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/* Computes the fastopen cookie for the IP path.
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* The path is a 128 bits long (pad with zeros for IPv4).
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*
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* The caller must check foc->len to determine if a valid cookie
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* has been generated successfully.
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*/
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void tcp_fastopen_cookie_gen(__be32 addr, struct tcp_fastopen_cookie *foc)
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void tcp_fastopen_cookie_gen(__be32 src, __be32 dst,
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struct tcp_fastopen_cookie *foc)
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{
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__be32 peer_addr[4] = { addr, 0, 0, 0 };
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__be32 path[4] = { src, dst, 0, 0 };
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struct tcp_fastopen_context *ctx;
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rcu_read_lock();
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ctx = rcu_dereference(tcp_fastopen_ctx);
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if (ctx) {
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crypto_cipher_encrypt_one(ctx->tfm,
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foc->val,
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(__u8 *)peer_addr);
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crypto_cipher_encrypt_one(ctx->tfm, foc->val, (__u8 *)path);
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foc->len = TCP_FASTOPEN_COOKIE_SIZE;
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}
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rcu_read_unlock();
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@ -1316,9 +1316,11 @@ static bool tcp_fastopen_check(struct sock *sk, struct sk_buff *skb,
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tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
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return true;
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}
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if (foc->len == TCP_FASTOPEN_COOKIE_SIZE) {
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if ((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_CHKED) == 0) {
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tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr, valid_foc);
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tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
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ip_hdr(skb)->daddr, valid_foc);
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if ((valid_foc->len != TCP_FASTOPEN_COOKIE_SIZE) ||
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memcmp(&foc->val[0], &valid_foc->val[0],
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TCP_FASTOPEN_COOKIE_SIZE) != 0)
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@ -1329,14 +1331,16 @@ static bool tcp_fastopen_check(struct sock *sk, struct sk_buff *skb,
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tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
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return true;
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} else if (foc->len == 0) { /* Client requesting a cookie */
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tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr, valid_foc);
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tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
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ip_hdr(skb)->daddr, valid_foc);
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NET_INC_STATS_BH(sock_net(sk),
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LINUX_MIB_TCPFASTOPENCOOKIEREQD);
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} else {
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/* Client sent a cookie with wrong size. Treat it
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* the same as invalid and return a valid one.
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*/
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tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr, valid_foc);
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tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
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ip_hdr(skb)->daddr, valid_foc);
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}
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return false;
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}
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