diff options
Diffstat (limited to 'net/ipv4/tcp_ao.c')
| -rw-r--r-- | net/ipv4/tcp_ao.c | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c index de3710758d55..6c5815713b73 100644 --- a/net/ipv4/tcp_ao.c +++ b/net/ipv4/tcp_ao.c @@ -761,6 +761,148 @@ void tcp_ao_syncookie(struct sock *sk, const struct sk_buff *skb, treq->maclen = tcp_ao_maclen(key); } +static enum skb_drop_reason +tcp_ao_verify_hash(const struct sock *sk, const struct sk_buff *skb, + unsigned short int family, struct tcp_ao_info *info, + const struct tcp_ao_hdr *aoh, struct tcp_ao_key *key, + u8 *traffic_key, u8 *phash, u32 sne) +{ + u8 maclen = aoh->length - sizeof(struct tcp_ao_hdr); + const struct tcphdr *th = tcp_hdr(skb); + void *hash_buf = NULL; + + if (maclen != tcp_ao_maclen(key)) + return SKB_DROP_REASON_TCP_AOFAILURE; + + hash_buf = kmalloc(tcp_ao_digest_size(key), GFP_ATOMIC); + if (!hash_buf) + return SKB_DROP_REASON_NOT_SPECIFIED; + + /* XXX: make it per-AF callback? */ + tcp_ao_hash_skb(family, hash_buf, key, sk, skb, traffic_key, + (phash - (u8 *)th), sne); + if (memcmp(phash, hash_buf, maclen)) { + kfree(hash_buf); + return SKB_DROP_REASON_TCP_AOFAILURE; + } + kfree(hash_buf); + return SKB_NOT_DROPPED_YET; +} + +enum skb_drop_reason +tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb, + unsigned short int family, const struct request_sock *req, + const struct tcp_ao_hdr *aoh) +{ + const struct tcphdr *th = tcp_hdr(skb); + u8 *phash = (u8 *)(aoh + 1); /* hash goes just after the header */ + struct tcp_ao_info *info; + enum skb_drop_reason ret; + struct tcp_ao_key *key; + __be32 sisn, disn; + u8 *traffic_key; + u32 sne = 0; + + info = rcu_dereference(tcp_sk(sk)->ao_info); + if (!info) + return SKB_DROP_REASON_TCP_AOUNEXPECTED; + + if (unlikely(th->syn)) { + sisn = th->seq; + disn = 0; + } + + /* Fast-path */ + if (likely((1 << sk->sk_state) & TCP_AO_ESTABLISHED)) { + enum skb_drop_reason err; + struct tcp_ao_key *current_key; + + /* Check if this socket's rnext_key matches the keyid in the + * packet. If not we lookup the key based on the keyid + * matching the rcvid in the mkt. + */ + key = READ_ONCE(info->rnext_key); + if (key->rcvid != aoh->keyid) { + key = tcp_ao_established_key(info, -1, aoh->keyid); + if (!key) + goto key_not_found; + } + + /* Delayed retransmitted SYN */ + if (unlikely(th->syn && !th->ack)) + goto verify_hash; + + sne = 0; + /* Established socket, traffic key are cached */ + traffic_key = rcv_other_key(key); + err = tcp_ao_verify_hash(sk, skb, family, info, aoh, key, + traffic_key, phash, sne); + if (err) + return err; + current_key = READ_ONCE(info->current_key); + /* Key rotation: the peer asks us to use new key (RNext) */ + if (unlikely(aoh->rnext_keyid != current_key->sndid)) { + /* If the key is not found we do nothing. */ + key = tcp_ao_established_key(info, aoh->rnext_keyid, -1); + if (key) + /* pairs with tcp_ao_del_cmd */ + WRITE_ONCE(info->current_key, key); + } + return SKB_NOT_DROPPED_YET; + } + + /* Lookup key based on peer address and keyid. + * current_key and rnext_key must not be used on tcp listen + * sockets as otherwise: + * - request sockets would race on those key pointers + * - tcp_ao_del_cmd() allows async key removal + */ + key = tcp_ao_inbound_lookup(family, sk, skb, -1, aoh->keyid); + if (!key) + goto key_not_found; + + if (th->syn && !th->ack) + goto verify_hash; + + if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_NEW_SYN_RECV)) { + /* Make the initial syn the likely case here */ + if (unlikely(req)) { + sne = 0; + sisn = htonl(tcp_rsk(req)->rcv_isn); + disn = htonl(tcp_rsk(req)->snt_isn); + } else if (unlikely(th->ack && !th->syn)) { + /* Possible syncookie packet */ + sisn = htonl(ntohl(th->seq) - 1); + disn = htonl(ntohl(th->ack_seq) - 1); + sne = 0; + } else if (unlikely(!th->syn)) { + /* no way to figure out initial sisn/disn - drop */ + return SKB_DROP_REASON_TCP_FLAGS; + } + } else if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { + disn = info->lisn; + if (th->syn || th->rst) + sisn = th->seq; + else + sisn = info->risn; + } else { + WARN_ONCE(1, "TCP-AO: Unexpected sk_state %d", sk->sk_state); + return SKB_DROP_REASON_TCP_AOFAILURE; + } +verify_hash: + traffic_key = kmalloc(tcp_ao_digest_size(key), GFP_ATOMIC); + if (!traffic_key) + return SKB_DROP_REASON_NOT_SPECIFIED; + tcp_ao_calc_key_skb(key, traffic_key, skb, sisn, disn, family); + ret = tcp_ao_verify_hash(sk, skb, family, info, aoh, key, + traffic_key, phash, sne); + kfree(traffic_key); + return ret; + +key_not_found: + return SKB_DROP_REASON_TCP_AOKEYNOTFOUND; +} + static int tcp_ao_cache_traffic_keys(const struct sock *sk, struct tcp_ao_info *ao, struct tcp_ao_key *ao_key) |