This is required because tcp ipv4 sometimes sends replies without allocating a full skb that can be signed by tcp authopt.
Handle this with additional code in tcp authopt.
Signed-off-by: Leonard Crestez cdleonard@gmail.com --- include/net/tcp_authopt.h | 7 ++ net/ipv4/tcp_authopt.c | 147 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 154 insertions(+)
diff --git a/include/net/tcp_authopt.h b/include/net/tcp_authopt.h index 422f0034d32b..b012eaaf416f 100644 --- a/include/net/tcp_authopt.h +++ b/include/net/tcp_authopt.h @@ -81,10 +81,17 @@ static inline struct tcp_authopt_key_info *tcp_authopt_select_key( } int tcp_authopt_hash( char *hash_location, struct tcp_authopt_key_info *key, struct sock *sk, struct sk_buff *skb); +int tcp_v4_authopt_hash_reply( + char *hash_location, + struct tcp_authopt_info *info, + struct tcp_authopt_key_info *key, + __be32 saddr, + __be32 daddr, + struct tcphdr *th); int __tcp_authopt_openreq(struct sock *newsk, const struct sock *oldsk, struct request_sock *req); static inline int tcp_authopt_openreq( struct sock *newsk, const struct sock *oldsk, struct request_sock *req) diff --git a/net/ipv4/tcp_authopt.c b/net/ipv4/tcp_authopt.c index 41f844d5d49a..756182401a3b 100644 --- a/net/ipv4/tcp_authopt.c +++ b/net/ipv4/tcp_authopt.c @@ -798,10 +798,74 @@ static int tcp_authopt_get_traffic_key(struct sock *sk, out: tcp_authopt_put_kdf_shash(key, kdf_tfm); return err; }
+struct tcp_v4_authopt_context_data { + __be32 saddr; + __be32 daddr; + __be16 sport; + __be16 dport; + __be32 sisn; + __be32 disn; + __be16 digestbits; +} __packed; + +static int tcp_v4_authopt_get_traffic_key_noskb( + struct tcp_authopt_key_info *key, + __be32 saddr, + __be32 daddr, + __be16 sport, + __be16 dport, + __be32 sisn, + __be32 disn, + u8 *traffic_key) +{ + int err; + struct crypto_shash *kdf_tfm; + SHASH_DESC_ON_STACK(desc, kdf_tfm); + struct tcp_v4_authopt_context_data data; + BUILD_BUG_ON(sizeof(data) != 22); + + kdf_tfm = tcp_authopt_get_kdf_shash(key); + if (IS_ERR(kdf_tfm)) + return PTR_ERR(kdf_tfm); + + err = tcp_authopt_setkey(kdf_tfm, key); + if (err) + goto out; + + desc->tfm = kdf_tfm; + err = crypto_shash_init(desc); + if (err) + goto out; + + // RFC5926 section 3.1.1.1 + // Separate to keep alignment semi-sane + err = crypto_shash_update(desc, "\x01TCP-AO", 7); + if (err) + return err; + data.saddr = saddr; + data.daddr = daddr; + data.sport = sport; + data.dport = dport; + data.sisn = sisn; + data.disn = disn; + data.digestbits = htons(crypto_shash_digestsize(desc->tfm) * 8); + + err = crypto_shash_update(desc, (u8*)&data, sizeof(data)); + if (err) + goto out; + err = crypto_shash_final(desc, traffic_key); + if (err) + goto out; + +out: + tcp_authopt_put_kdf_shash(key, kdf_tfm); + return err; +} + static int crypto_shash_update_zero(struct shash_desc *desc, int len) { u8 zero = 0; int i, err;
@@ -1122,10 +1186,93 @@ int tcp_authopt_hash(char *hash_location, memcpy(hash_location, macbuf, TCP_AUTHOPT_MACLEN);
return 0; }
+/** + * tcp_v4_authopt_hash_hdr - Hash tcp+ipv4 header without SKB + * + * The key must come from tcp_authopt_select_key. + */ +int tcp_v4_authopt_hash_reply(char *hash_location, + struct tcp_authopt_info *info, + struct tcp_authopt_key_info *key, + __be32 saddr, + __be32 daddr, + struct tcphdr *th) +{ + struct crypto_shash *mac_tfm; + u8 macbuf[TCP_AUTHOPT_MAXMACBUF]; + u8 traffic_key[TCP_AUTHOPT_MAX_TRAFFIC_KEY_LEN]; + SHASH_DESC_ON_STACK(desc, tfm); + __be32 sne = 0; + int err; + + /* Call special code path for computing traffic key without skb + * This can be called from tcp_v4_reqsk_send_ack so caching would be + * difficult here. + */ + err = tcp_v4_authopt_get_traffic_key_noskb( + key, + saddr, + daddr, + th->source, + th->dest, + htonl(info->src_isn), + htonl(info->dst_isn), + traffic_key); + if (err) + goto out_err_traffic_key; + + /* Init mac shash */ + mac_tfm = tcp_authopt_get_mac_shash(key); + if (IS_ERR(mac_tfm)) + return PTR_ERR(mac_tfm); + err = crypto_shash_setkey(mac_tfm, traffic_key, key->alg->traffic_key_len); + if (err) + goto out_err; + + desc->tfm = mac_tfm; + err = crypto_shash_init(desc); + if (err) + return err; + + err = crypto_shash_update(desc, (u8 *)&sne, 4); + if (err) + return err; + + err = tcp_authopt_hash_tcp4_pseudoheader(desc, saddr, daddr, th->doff * 4); + if (err) + return err; + + // TCP header with checksum set to zero. Caller ensures this. + if (WARN_ON_ONCE(th->check != 0)) + goto out_err; + err = crypto_shash_update(desc, (u8 *)th, sizeof(*th)); + if (err) + goto out_err; + + // TCP options + err = tcp_authopt_hash_opts(desc, th, !(key->flags & TCP_AUTHOPT_KEY_EXCLUDE_OPTS)); + if (err) + goto out_err; + + err = crypto_shash_final(desc, macbuf); + if (err) + goto out_err; + memcpy(hash_location, macbuf, TCP_AUTHOPT_MACLEN); + + tcp_authopt_put_mac_shash(key, mac_tfm); + return 0; + +out_err: + tcp_authopt_put_mac_shash(key, mac_tfm); +out_err_traffic_key: + memset(hash_location, 0, TCP_AUTHOPT_MACLEN); + return err; +} + static struct tcp_authopt_key_info *tcp_authopt_lookup_recv(struct sock *sk, struct sk_buff *skb, struct tcp_authopt_info *info, int recv_id) {