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Miller" Cc: linux-kernel@vger.kernel.org, Dmitry Safonov , Andy Lutomirski , Ard Biesheuvel , Bob Gilligan , Dan Carpenter , David Laight , Dmitry Safonov <0x7f454c46@gmail.com>, Donald Cassidy , Eric Biggers , "Eric W. Biederman" , Francesco Ruggeri , Herbert Xu , Hideaki YOSHIFUJI , Ivan Delalande , Leonard Crestez , Salam Noureddine , netdev@vger.kernel.org Subject: [PATCH v7 04/22] net/tcp: Prevent TCP-MD5 with TCP-AO being set Date: Thu, 15 Jun 2023 00:09:29 +0100 Message-Id: <20230614230947.3954084-5-dima@arista.com> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230614230947.3954084-1-dima@arista.com> References: <20230614230947.3954084-1-dima@arista.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: kuba@kernel.org Be as conservative as possible: if there is TCP-MD5 key for a given peer regardless of L3 interface - don't allow setting TCP-AO key for the same peer. According to RFC5925, TCP-AO is supposed to replace TCP-MD5 and there can't be any switch between both on any connected tuple. Later it can be relaxed, if there's a use, but in the beginning restrict any intersection. Note: it's still should be possible to set both TCP-MD5 and TCP-AO keys on a listening socket for *different* peers. Co-developed-by: Francesco Ruggeri Signed-off-by: Francesco Ruggeri Co-developed-by: Salam Noureddine Signed-off-by: Salam Noureddine Signed-off-by: Dmitry Safonov --- include/net/tcp.h | 43 +++++++++++++++++++++++++++++++++++++-- include/net/tcp_ao.h | 15 ++++++++++++++ net/ipv4/tcp_ao.c | 40 ++++++++++++++++++++++++++++++++++++ net/ipv4/tcp_ipv4.c | 14 ++++++++++--- net/ipv4/tcp_output.c | 47 +++++++++++++++++++++++++++++++++++++++++++ net/ipv6/tcp_ao.c | 18 +++++++++++++++++ net/ipv6/tcp_ipv6.c | 26 ++++++++++++++++++++---- 7 files changed, 194 insertions(+), 9 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 511514e59772..219604c8ae6e 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1707,6 +1707,7 @@ int tcp_md5_key_copy(struct sock *sk, const union tcp_md5_addr *addr, int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, int family, u8 prefixlen, int l3index, u8 flags); +void tcp_clear_md5_list(struct sock *sk); struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, const struct sock *addr_sk); @@ -1715,14 +1716,23 @@ struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, extern struct static_key_false_deferred tcp_md5_needed; struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk, int l3index, const union tcp_md5_addr *addr, - int family); + int family, bool any_l3index); static inline struct tcp_md5sig_key * tcp_md5_do_lookup(const struct sock *sk, int l3index, const union tcp_md5_addr *addr, int family) { if (!static_branch_unlikely(&tcp_md5_needed.key)) return NULL; - return __tcp_md5_do_lookup(sk, l3index, addr, family); + return __tcp_md5_do_lookup(sk, l3index, addr, family, false); +} + +static inline struct tcp_md5sig_key * +tcp_md5_do_lookup_any_l3index(const struct sock *sk, + const union tcp_md5_addr *addr, int family) +{ + if (!static_branch_unlikely(&tcp_md5_needed.key)) + return NULL; + return __tcp_md5_do_lookup(sk, 0, addr, family, true); } enum skb_drop_reason @@ -1740,6 +1750,13 @@ tcp_md5_do_lookup(const struct sock *sk, int l3index, return NULL; } +static inline struct tcp_md5sig_key * +tcp_md5_do_lookup_any_l3index(const struct sock *sk, + const union tcp_md5_addr *addr, int family) +{ + return NULL; +} + 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, @@ -2101,6 +2118,9 @@ struct tcp_sock_af_ops { int optname, sockptr_t optval, int optlen); + struct tcp_ao_key *(*ao_lookup)(const struct sock *sk, + struct sock *addr_sk, + int sndid, int rcvid); #endif }; @@ -2513,4 +2533,23 @@ static inline u64 tcp_transmit_time(const struct sock *sk) return 0; } +static inline bool tcp_ao_required(struct sock *sk, const void *saddr, + int family) +{ +#ifdef CONFIG_TCP_AO + struct tcp_ao_info *ao_info; + struct tcp_ao_key *ao_key; + + ao_info = rcu_dereference_check(tcp_sk(sk)->ao_info, + lockdep_sock_is_held(sk)); + if (!ao_info) + return false; + + ao_key = tcp_ao_do_lookup(sk, saddr, family, -1, -1, 0); + if (ao_info->ao_required || ao_key) + return true; +#endif + return false; +} + #endif /* _TCP_H */ diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h index 916df79450e0..73f584b499f6 100644 --- a/include/net/tcp_ao.h +++ b/include/net/tcp_ao.h @@ -98,12 +98,27 @@ struct tcp_ao_info { int tcp_parse_ao(struct sock *sk, int cmd, unsigned short int family, sockptr_t optval, int optlen); void tcp_ao_destroy_sock(struct sock *sk); +struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk, + const union tcp_ao_addr *addr, + int family, int sndid, int rcvid, u16 port); /* ipv4 specific functions */ int tcp_v4_parse_ao(struct sock *sk, int optname, sockptr_t optval, int optlen); +struct tcp_ao_key *tcp_v4_ao_lookup(const struct sock *sk, struct sock *addr_sk, + int sndid, int rcvid); /* ipv6 specific functions */ +struct tcp_ao_key *tcp_v6_ao_lookup(const struct sock *sk, + struct sock *addr_sk, + int sndid, int rcvid); int tcp_v6_parse_ao(struct sock *sk, int cmd, sockptr_t optval, int optlen); #else +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, u16 port) +{ + return NULL; +} + static inline void tcp_ao_destroy_sock(struct sock *sk) { } diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c index 356747d064e8..b4d0b9f9e10a 100644 --- a/net/ipv4/tcp_ao.c +++ b/net/ipv4/tcp_ao.c @@ -172,6 +172,14 @@ void tcp_ao_destroy_sock(struct sock *sk) kfree_rcu(ao, rcu); } +struct tcp_ao_key *tcp_v4_ao_lookup(const struct sock *sk, struct sock *addr_sk, + int sndid, int rcvid) +{ + union tcp_ao_addr *addr = (union tcp_ao_addr *)&addr_sk->sk_daddr; + + return tcp_ao_do_lookup(sk, addr, AF_INET, sndid, rcvid, 0); +} + static bool tcp_ao_can_set_current_rnext(struct sock *sk) { /* There aren't current/rnext keys on TCP_LISTEN sockets */ @@ -486,6 +494,10 @@ static int tcp_ao_add_cmd(struct sock *sk, unsigned short int family, return -EINVAL; } + /* Don't allow keys for peers that have a matching TCP-MD5 key */ + if (tcp_md5_do_lookup_any_l3index(sk, addr, family)) + return -EKEYREJECTED; + ao_info = setsockopt_ao_info(sk); if (IS_ERR(ao_info)) return PTR_ERR(ao_info); @@ -690,6 +702,31 @@ static int tcp_ao_del_cmd(struct sock *sk, unsigned short int family, return -ENOENT; } +/* cmd.ao_required makes a socket TCP-AO only. + * Don't allow any md5 keys for any l3intf on the socket together with it. + * Restricting it early in setsockopt() removes a check for + * ao_info->ao_required on inbound tcp segment fast-path. + */ +static inline int tcp_ao_required_verify(struct sock *sk) +{ +#ifdef CONFIG_TCP_MD5SIG + const struct tcp_md5sig_info *md5sig; + + if (!static_branch_unlikely(&tcp_md5_needed.key)) + return 0; + + md5sig = rcu_dereference_check(tcp_sk(sk)->md5sig_info, + lockdep_sock_is_held(sk)); + if (!md5sig) + return 0; + + if (rcu_dereference_check(hlist_first_rcu(&md5sig->head), + lockdep_sock_is_held(sk))) + return 1; +#endif + return 0; +} + static int tcp_ao_info_cmd(struct sock *sk, unsigned short int family, sockptr_t optval, int optlen) { @@ -724,6 +761,9 @@ static int tcp_ao_info_cmd(struct sock *sk, unsigned short int family, first = true; } + if (cmd.ao_required && tcp_ao_required_verify(sk)) + return -EKEYREJECTED; + /* For sockets in TCP_CLOSED it's possible set keys that aren't * matching the future peer (address/port/VRF/etc), * tcp_ao_connect_init() will choose a correct matching MKT diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 6248af483b67..b06b286f9ec2 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1074,7 +1074,7 @@ static bool better_md5_match(struct tcp_md5sig_key *old, struct tcp_md5sig_key * /* Find the Key structure for an address. */ struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk, int l3index, const union tcp_md5_addr *addr, - int family) + int family, bool any_l3index) { const struct tcp_sock *tp = tcp_sk(sk); struct tcp_md5sig_key *key; @@ -1093,7 +1093,8 @@ struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk, int l3index, lockdep_sock_is_held(sk)) { if (key->family != family) continue; - if (key->flags & TCP_MD5SIG_FLAG_IFINDEX && key->l3index != l3index) + if (!any_l3index && key->flags & TCP_MD5SIG_FLAG_IFINDEX && + key->l3index != l3index) continue; if (family == AF_INET) { mask = inet_make_mask(key->prefixlen); @@ -1305,7 +1306,7 @@ int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, int family, } EXPORT_SYMBOL(tcp_md5_do_del); -static void tcp_clear_md5_list(struct sock *sk) +void tcp_clear_md5_list(struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk); struct tcp_md5sig_key *key; @@ -1375,6 +1376,12 @@ static int tcp_v4_parse_md5_keys(struct sock *sk, int optname, if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN) return -EINVAL; + /* Don't allow keys for peers that have a matching TCP-AO key. + * See the comment in tcp_ao_add_cmd() + */ + if (tcp_ao_required(sk, addr, AF_INET)) + return -EKEYREJECTED; + return tcp_md5_do_add(sk, addr, AF_INET, prefixlen, l3index, flags, cmd.tcpm_key, cmd.tcpm_keylen); } @@ -2270,6 +2277,7 @@ static const struct tcp_sock_af_ops tcp_sock_ipv4_specific = { .md5_parse = tcp_v4_parse_md5_keys, #endif #ifdef CONFIG_TCP_AO + .ao_lookup = tcp_v4_ao_lookup, .ao_parse = tcp_v4_parse_ao, #endif }; diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index cfe128b81a01..324b241e95bc 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -3839,6 +3839,53 @@ int tcp_connect(struct sock *sk) tcp_call_bpf(sk, BPF_SOCK_OPS_TCP_CONNECT_CB, 0, NULL); +#if defined(CONFIG_TCP_MD5SIG) && defined(CONFIG_TCP_AO) + /* Has to be checked late, after setting daddr/saddr/ops. + * Return error if the peer has both a md5 and a tcp-ao key + * configured as this is ambiguous. + */ + if (unlikely(rcu_dereference_protected(tp->md5sig_info, + lockdep_sock_is_held(sk)))) { + bool needs_md5 = !!tp->af_specific->md5_lookup(sk, sk); + bool needs_ao = !!tp->af_specific->ao_lookup(sk, sk, -1, -1); + struct tcp_ao_info *ao_info; + + ao_info = rcu_dereference_check(tp->ao_info, + lockdep_sock_is_held(sk)); + if (ao_info) { + /* This is an extra check: tcp_ao_required() in + * tcp_v{4,6}_parse_md5_keys() should prevent adding + * md5 keys on ao_required socket. + */ + needs_ao |= ao_info->ao_required; + WARN_ON_ONCE(ao_info->ao_required && needs_md5); + } + if (needs_md5 && needs_ao) + return -EKEYREJECTED; + + /* If we have a matching md5 key and no matching tcp-ao key + * then free up ao_info if allocated. + */ + if (needs_md5) { + tcp_ao_destroy_sock(sk); + } else if (needs_ao) { + tcp_clear_md5_list(sk); + kfree(rcu_replace_pointer(tp->md5sig_info, NULL, + lockdep_sock_is_held(sk))); + } + } +#endif +#ifdef CONFIG_TCP_AO + if (unlikely(rcu_dereference_protected(tp->ao_info, + lockdep_sock_is_held(sk)))) { + /* Don't allow connecting if ao is configured but no + * matching key is found. + */ + if (!tp->af_specific->ao_lookup(sk, sk, -1, -1)) + return -EKEYREJECTED; + } +#endif + if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) return -EHOSTUNREACH; /* Routing failure or similar. */ diff --git a/net/ipv6/tcp_ao.c b/net/ipv6/tcp_ao.c index d0aa6414b7d9..3d2be5f73cf0 100644 --- a/net/ipv6/tcp_ao.c +++ b/net/ipv6/tcp_ao.c @@ -12,6 +12,24 @@ #include #include +struct tcp_ao_key *tcp_v6_ao_do_lookup(const struct sock *sk, + const struct in6_addr *addr, + int sndid, int rcvid) +{ + return tcp_ao_do_lookup(sk, (union tcp_ao_addr *)addr, AF_INET6, + sndid, rcvid, 0); +} + +struct tcp_ao_key *tcp_v6_ao_lookup(const struct sock *sk, + struct sock *addr_sk, + int sndid, int rcvid) +{ + struct in6_addr *addr = &addr_sk->sk_v6_daddr; + + return tcp_v6_ao_do_lookup(sk, addr, sndid, rcvid); +} +EXPORT_SYMBOL_GPL(tcp_v6_ao_lookup); + int tcp_v6_parse_ao(struct sock *sk, int cmd, sockptr_t optval, int optlen) { diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 84e69d5f2f81..a946a3a66a92 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -603,6 +603,7 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname, { struct tcp_md5sig cmd; struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&cmd.tcpm_addr; + union tcp_ao_addr *addr; int l3index = 0; u8 prefixlen; u8 flags; @@ -657,13 +658,28 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname, if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN) return -EINVAL; - if (ipv6_addr_v4mapped(&sin6->sin6_addr)) - return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin6->sin6_addr.s6_addr32[3], + if (ipv6_addr_v4mapped(&sin6->sin6_addr)) { + addr = (union tcp_md5_addr *)&sin6->sin6_addr.s6_addr32[3]; + + /* Don't allow keys for peers that have a matching TCP-AO key. + * See the comment in tcp_ao_add_cmd() + */ + if (tcp_ao_required(sk, addr, AF_INET)) + return -EKEYREJECTED; + return tcp_md5_do_add(sk, addr, AF_INET, prefixlen, l3index, flags, cmd.tcpm_key, cmd.tcpm_keylen); + } - return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin6->sin6_addr, - AF_INET6, prefixlen, l3index, flags, + addr = (union tcp_md5_addr *)&sin6->sin6_addr; + + /* Don't allow keys for peers that have a matching TCP-AO key. + * See the comment in tcp_ao_add_cmd() + */ + if (tcp_ao_required(sk, addr, AF_INET6)) + return -EKEYREJECTED; + + return tcp_md5_do_add(sk, addr, AF_INET6, prefixlen, l3index, flags, cmd.tcpm_key, cmd.tcpm_keylen); } @@ -1903,6 +1919,7 @@ static const struct tcp_sock_af_ops tcp_sock_ipv6_specific = { .md5_parse = tcp_v6_parse_md5_keys, #endif #ifdef CONFIG_TCP_AO + .ao_lookup = tcp_v6_ao_lookup, .ao_parse = tcp_v6_parse_ao, #endif }; @@ -1934,6 +1951,7 @@ static const struct tcp_sock_af_ops tcp_sock_ipv6_mapped_specific = { .md5_parse = tcp_v6_parse_md5_keys, #endif #ifdef CONFIG_TCP_AO + .ao_lookup = tcp_v6_ao_lookup, .ao_parse = tcp_v6_parse_ao, #endif };