diff options
author | Dmitry Safonov <dima@arista.com> | 2023-10-23 21:22:04 +0200 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2023-10-27 11:35:45 +0200 |
commit | 0a3a809089eb1d4a0a2fd0c16b520d603988c859 (patch) | |
tree | b584ef3c79e149b5f9986ed02258d29a48569df8 /include/net | |
parent | net/tcp: Sign SYN-ACK segments with TCP-AO (diff) | |
download | linux-0a3a809089eb1d4a0a2fd0c16b520d603988c859.tar.xz linux-0a3a809089eb1d4a0a2fd0c16b520d603988c859.zip |
net/tcp: Verify inbound TCP-AO signed segments
Now there is a common function to verify signature on TCP segments:
tcp_inbound_hash(). It has checks for all possible cross-interactions
with MD5 signs as well as with unsigned segments.
The rules from RFC5925 are:
(1) Any TCP segment can have at max only one signature.
(2) TCP connections can't switch between using TCP-MD5 and TCP-AO.
(3) TCP-AO connections can't stop using AO, as well as unsigned
connections can't suddenly start using AO.
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>
Diffstat (limited to 'include/net')
-rw-r--r-- | include/net/dropreason-core.h | 17 | ||||
-rw-r--r-- | include/net/tcp.h | 53 | ||||
-rw-r--r-- | include/net/tcp_ao.h | 14 |
3 files changed, 82 insertions, 2 deletions
diff --git a/include/net/dropreason-core.h b/include/net/dropreason-core.h index 3af4464a9c5b..7637137ae33e 100644 --- a/include/net/dropreason-core.h +++ b/include/net/dropreason-core.h @@ -24,6 +24,10 @@ FN(TCP_MD5NOTFOUND) \ FN(TCP_MD5UNEXPECTED) \ FN(TCP_MD5FAILURE) \ + FN(TCP_AONOTFOUND) \ + FN(TCP_AOUNEXPECTED) \ + FN(TCP_AOKEYNOTFOUND) \ + FN(TCP_AOFAILURE) \ FN(SOCKET_BACKLOG) \ FN(TCP_FLAGS) \ FN(TCP_ZEROWINDOW) \ @@ -164,6 +168,19 @@ enum skb_drop_reason { */ SKB_DROP_REASON_TCP_MD5FAILURE, /** + * @SKB_DROP_REASON_TCP_AONOTFOUND: no TCP-AO hash and one was expected + */ + SKB_DROP_REASON_TCP_AONOTFOUND, + /** + * @SKB_DROP_REASON_TCP_AOUNEXPECTED: TCP-AO hash is present and it + * was not expected. + */ + SKB_DROP_REASON_TCP_AOUNEXPECTED, + /** @SKB_DROP_REASON_TCP_AOKEYNOTFOUND: TCP-AO key is unknown */ + SKB_DROP_REASON_TCP_AOKEYNOTFOUND, + /** @SKB_DROP_REASON_TCP_AOFAILURE: TCP-AO hash is wrong */ + SKB_DROP_REASON_TCP_AOFAILURE, + /** * @SKB_DROP_REASON_SOCKET_BACKLOG: failed to add skb to socket backlog ( * see LINUX_MIB_TCPBACKLOGDROP) */ diff --git a/include/net/tcp.h b/include/net/tcp.h index c7f80cc94d71..8e1f835bad22 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1809,7 +1809,7 @@ tcp_md5_do_lookup_any_l3index(const struct sock *sk, enum skb_drop_reason tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb, const void *saddr, const void *daddr, - int family, int dif, int sdif); + int family, int l3index, const __u8 *hash_location); #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) @@ -1831,7 +1831,7 @@ tcp_md5_do_lookup_any_l3index(const struct sock *sk, static inline enum skb_drop_reason tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb, const void *saddr, const void *daddr, - int family, int dif, int sdif) + int family, int l3index, const __u8 *hash_location) { return SKB_NOT_DROPPED_YET; } @@ -2730,4 +2730,53 @@ static inline bool tcp_ao_required(struct sock *sk, const void *saddr, return false; } +/* Called with rcu_read_lock() */ +static inline enum skb_drop_reason +tcp_inbound_hash(struct sock *sk, const struct request_sock *req, + const struct sk_buff *skb, + const void *saddr, const void *daddr, + int family, int dif, int sdif) +{ + const struct tcphdr *th = tcp_hdr(skb); + const struct tcp_ao_hdr *aoh; + const __u8 *md5_location; + int l3index; + + /* Invalid option or two times meet any of auth options */ + if (tcp_parse_auth_options(th, &md5_location, &aoh)) + return SKB_DROP_REASON_TCP_AUTH_HDR; + + if (req) { + if (tcp_rsk_used_ao(req) != !!aoh) + return SKB_DROP_REASON_TCP_AOFAILURE; + } + + /* sdif set, means packet ingressed via a device + * in an L3 domain and dif is set to the l3mdev + */ + l3index = sdif ? dif : 0; + + /* Fast path: unsigned segments */ + if (likely(!md5_location && !aoh)) { + /* Drop if there's TCP-MD5 or TCP-AO key with any rcvid/sndid + * for the remote peer. On TCP-AO established connection + * the last key is impossible to remove, so there's + * always at least one current_key. + */ + if (tcp_ao_required(sk, saddr, family)) + return SKB_DROP_REASON_TCP_AONOTFOUND; + if (unlikely(tcp_md5_do_lookup(sk, l3index, saddr, family))) { + NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND); + return SKB_DROP_REASON_TCP_MD5NOTFOUND; + } + return SKB_NOT_DROPPED_YET; + } + + if (aoh) + return tcp_inbound_ao_hash(sk, skb, family, req, aoh); + + return tcp_inbound_md5_hash(sk, skb, saddr, daddr, family, + l3index, md5_location); +} + #endif /* _TCP_H */ diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h index 1d69978e349a..1c7c0a5d1877 100644 --- a/include/net/tcp_ao.h +++ b/include/net/tcp_ao.h @@ -111,6 +111,9 @@ struct tcp6_ao_context { }; struct tcp_sigpool; +#define TCP_AO_ESTABLISHED (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_FIN_WAIT2 | \ + TCPF_CLOSE | TCPF_CLOSE_WAIT | \ + TCPF_LAST_ACK | TCPF_CLOSING) int tcp_ao_transmit_skb(struct sock *sk, struct sk_buff *skb, struct tcp_ao_key *key, struct tcphdr *th, @@ -130,6 +133,10 @@ int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx, unsigned int len, struct tcp_sigpool *hp); void tcp_ao_destroy_sock(struct sock *sk, bool twsk); void tcp_ao_time_wait(struct tcp_timewait_sock *tcptw, struct tcp_sock *tp); +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); struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk, const union tcp_ao_addr *addr, int family, int sndid, int rcvid); @@ -208,6 +215,13 @@ static inline void tcp_ao_syncookie(struct sock *sk, const struct sk_buff *skb, { } +static inline 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) +{ + return SKB_NOT_DROPPED_YET; +} + static inline struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk, const union tcp_ao_addr *addr, int family, int sndid, int rcvid) { |