From 86f1e3a8489f6a0232c1f3bc2bdb379f5ccdecec Mon Sep 17 00:00:00 2001 From: Leonard Crestez Date: Fri, 15 Oct 2021 10:26:04 +0300 Subject: tcp: md5: Fix overlap between vrf and non-vrf keys With net.ipv4.tcp_l3mdev_accept=1 it is possible for a listen socket to accept connection from the same client address in different VRFs. It is also possible to set different MD5 keys for these clients which differ only in the tcpm_l3index field. This appears to work when distinguishing between different VRFs but not between non-VRF and VRF connections. In particular: * tcp_md5_do_lookup_exact will match a non-vrf key against a vrf key. This means that adding a key with l3index != 0 after a key with l3index == 0 will cause the earlier key to be deleted. Both keys can be present if the non-vrf key is added later. * _tcp_md5_do_lookup can match a non-vrf key before a vrf key. This casues failures if the passwords differ. Fix this by making tcp_md5_do_lookup_exact perform an actual exact comparison on l3index and by making __tcp_md5_do_lookup perfer vrf-bound keys above other considerations like prefixlen. Fixes: dea53bb80e07 ("tcp: Add l3index to tcp_md5sig_key and md5 functions") Signed-off-by: Leonard Crestez Reviewed-by: David Ahern Signed-off-by: David S. Miller --- net/ipv4/tcp_ipv4.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) (limited to 'net/ipv4/tcp_ipv4.c') diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 2e62e0d6373a..f64b6c8380e8 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1037,6 +1037,20 @@ static void tcp_v4_reqsk_destructor(struct request_sock *req) DEFINE_STATIC_KEY_FALSE(tcp_md5_needed); EXPORT_SYMBOL(tcp_md5_needed); +static bool better_md5_match(struct tcp_md5sig_key *old, struct tcp_md5sig_key *new) +{ + if (!old) + return true; + + /* l3index always overrides non-l3index */ + if (old->l3index && new->l3index == 0) + return false; + if (old->l3index == 0 && new->l3index) + return true; + + return old->prefixlen < new->prefixlen; +} + /* 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, @@ -1074,8 +1088,7 @@ struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk, int l3index, match = false; } - if (match && (!best_match || - key->prefixlen > best_match->prefixlen)) + if (match && better_md5_match(best_match, key)) best_match = key; } return best_match; @@ -1105,7 +1118,7 @@ static struct tcp_md5sig_key *tcp_md5_do_lookup_exact(const struct sock *sk, lockdep_sock_is_held(sk)) { if (key->family != family) continue; - if (key->l3index && key->l3index != l3index) + if (key->l3index != l3index) continue; if (!memcmp(&key->addr, addr, size) && key->prefixlen == prefixlen) -- cgit From a76c2315bec7afeb9bafe776fe532106fa0a8b05 Mon Sep 17 00:00:00 2001 From: Leonard Crestez Date: Fri, 15 Oct 2021 10:26:05 +0300 Subject: tcp: md5: Allow MD5SIG_FLAG_IFINDEX with ifindex=0 Multiple VRFs are generally meant to be "separate" but right now md5 keys for the default VRF also affect connections inside VRFs if the IP addresses happen to overlap. So far the combination of TCP_MD5SIG_FLAG_IFINDEX with tcpm_ifindex == 0 was an error, accept this to mean "key only applies to default VRF". This is what applications using VRFs for traffic separation want. Signed-off-by: Leonard Crestez Reviewed-by: David Ahern Signed-off-by: David S. Miller --- net/ipv4/tcp_ipv4.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) (limited to 'net/ipv4/tcp_ipv4.c') diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index f64b6c8380e8..5b8ce65dfc06 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1073,7 +1073,7 @@ 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->l3index && key->l3index != l3index) + if (key->flags & TCP_MD5SIG_FLAG_IFINDEX && key->l3index != l3index) continue; if (family == AF_INET) { mask = inet_make_mask(key->prefixlen); @@ -1098,7 +1098,7 @@ EXPORT_SYMBOL(__tcp_md5_do_lookup); static struct tcp_md5sig_key *tcp_md5_do_lookup_exact(const struct sock *sk, const union tcp_md5_addr *addr, int family, u8 prefixlen, - int l3index) + int l3index, u8 flags) { const struct tcp_sock *tp = tcp_sk(sk); struct tcp_md5sig_key *key; @@ -1118,6 +1118,8 @@ static struct tcp_md5sig_key *tcp_md5_do_lookup_exact(const struct sock *sk, lockdep_sock_is_held(sk)) { if (key->family != family) continue; + if ((key->flags & TCP_MD5SIG_FLAG_IFINDEX) != (flags & TCP_MD5SIG_FLAG_IFINDEX)) + continue; if (key->l3index != l3index) continue; if (!memcmp(&key->addr, addr, size) && @@ -1142,7 +1144,7 @@ EXPORT_SYMBOL(tcp_v4_md5_lookup); /* This can be called on a newly created socket, from other files */ int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, - int family, u8 prefixlen, int l3index, + int family, u8 prefixlen, int l3index, u8 flags, const u8 *newkey, u8 newkeylen, gfp_t gfp) { /* Add Key to the list */ @@ -1150,7 +1152,7 @@ int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, struct tcp_sock *tp = tcp_sk(sk); struct tcp_md5sig_info *md5sig; - key = tcp_md5_do_lookup_exact(sk, addr, family, prefixlen, l3index); + key = tcp_md5_do_lookup_exact(sk, addr, family, prefixlen, l3index, flags); if (key) { /* Pre-existing entry - just update that one. * Note that the key might be used concurrently. @@ -1195,6 +1197,7 @@ int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, key->family = family; key->prefixlen = prefixlen; key->l3index = l3index; + key->flags = flags; memcpy(&key->addr, addr, (family == AF_INET6) ? sizeof(struct in6_addr) : sizeof(struct in_addr)); @@ -1204,11 +1207,11 @@ int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, EXPORT_SYMBOL(tcp_md5_do_add); int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, int family, - u8 prefixlen, int l3index) + u8 prefixlen, int l3index, u8 flags) { struct tcp_md5sig_key *key; - key = tcp_md5_do_lookup_exact(sk, addr, family, prefixlen, l3index); + key = tcp_md5_do_lookup_exact(sk, addr, family, prefixlen, l3index, flags); if (!key) return -ENOENT; hlist_del_rcu(&key->node); @@ -1242,6 +1245,7 @@ static int tcp_v4_parse_md5_keys(struct sock *sk, int optname, const union tcp_md5_addr *addr; u8 prefixlen = 32; int l3index = 0; + u8 flags; if (optlen < sizeof(cmd)) return -EINVAL; @@ -1252,6 +1256,8 @@ static int tcp_v4_parse_md5_keys(struct sock *sk, int optname, if (sin->sin_family != AF_INET) return -EINVAL; + flags = cmd.tcpm_flags & TCP_MD5SIG_FLAG_IFINDEX; + if (optname == TCP_MD5SIG_EXT && cmd.tcpm_flags & TCP_MD5SIG_FLAG_PREFIX) { prefixlen = cmd.tcpm_prefixlen; @@ -1259,7 +1265,7 @@ static int tcp_v4_parse_md5_keys(struct sock *sk, int optname, return -EINVAL; } - if (optname == TCP_MD5SIG_EXT && + if (optname == TCP_MD5SIG_EXT && cmd.tcpm_ifindex && cmd.tcpm_flags & TCP_MD5SIG_FLAG_IFINDEX) { struct net_device *dev; @@ -1280,12 +1286,12 @@ static int tcp_v4_parse_md5_keys(struct sock *sk, int optname, addr = (union tcp_md5_addr *)&sin->sin_addr.s_addr; if (!cmd.tcpm_keylen) - return tcp_md5_do_del(sk, addr, AF_INET, prefixlen, l3index); + return tcp_md5_do_del(sk, addr, AF_INET, prefixlen, l3index, flags); if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN) return -EINVAL; - return tcp_md5_do_add(sk, addr, AF_INET, prefixlen, l3index, + return tcp_md5_do_add(sk, addr, AF_INET, prefixlen, l3index, flags, cmd.tcpm_key, cmd.tcpm_keylen, GFP_KERNEL); } @@ -1609,7 +1615,7 @@ struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, * memory, then we end up not copying the key * across. Shucks. */ - tcp_md5_do_add(newsk, addr, AF_INET, 32, l3index, + tcp_md5_do_add(newsk, addr, AF_INET, 32, l3index, key->flags, key->key, key->keylen, GFP_ATOMIC); sk_nocaps_add(newsk, NETIF_F_GSO_MASK); } -- cgit