From 86f1e3a8489f6a0232c1f3bc2bdb379f5ccdecec Mon Sep 17 00:00:00 2001 From: Leonard Crestez Date: Fri, 15 Oct 2021 10:26:04 +0300 Subject: [PATCH 1/4] 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(-) 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) From a76c2315bec7afeb9bafe776fe532106fa0a8b05 Mon Sep 17 00:00:00 2001 From: Leonard Crestez Date: Fri, 15 Oct 2021 10:26:05 +0300 Subject: [PATCH 2/4] 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 --- include/net/tcp.h | 5 +++-- net/ipv4/tcp_ipv4.c | 26 ++++++++++++++++---------- net/ipv6/tcp_ipv6.c | 15 +++++++++------ 3 files changed, 28 insertions(+), 18 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 3166dc15d7d6..60c384569e9c 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1576,6 +1576,7 @@ struct tcp_md5sig_key { u8 keylen; u8 family; /* AF_INET or AF_INET6 */ u8 prefixlen; + u8 flags; union tcp_md5_addr addr; int l3index; /* set if key added with L3 scope */ u8 key[TCP_MD5SIG_MAXKEYLEN]; @@ -1621,10 +1622,10 @@ struct tcp_md5sig_pool { int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key, const struct sock *sk, const struct sk_buff *skb); 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); int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, - int family, u8 prefixlen, int l3index); + int family, u8 prefixlen, int l3index, u8 flags); struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, const struct sock *addr_sk); 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); } diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 0ce52d46e4f8..b03dd02c9f13 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -599,6 +599,7 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname, struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&cmd.tcpm_addr; int l3index = 0; u8 prefixlen; + u8 flags; if (optlen < sizeof(cmd)) return -EINVAL; @@ -609,6 +610,8 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname, if (sin6->sin6_family != AF_INET6) 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; @@ -619,7 +622,7 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname, prefixlen = ipv6_addr_v4mapped(&sin6->sin6_addr) ? 32 : 128; } - if (optname == TCP_MD5SIG_EXT && + if (optname == TCP_MD5SIG_EXT && cmd.tcpm_ifindex && cmd.tcpm_flags & TCP_MD5SIG_FLAG_IFINDEX) { struct net_device *dev; @@ -640,9 +643,9 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname, if (ipv6_addr_v4mapped(&sin6->sin6_addr)) return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin6->sin6_addr.s6_addr32[3], AF_INET, prefixlen, - l3index); + l3index, flags); return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin6->sin6_addr, - AF_INET6, prefixlen, l3index); + AF_INET6, prefixlen, l3index, flags); } if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN) @@ -650,12 +653,12 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname, if (ipv6_addr_v4mapped(&sin6->sin6_addr)) return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin6->sin6_addr.s6_addr32[3], - AF_INET, prefixlen, l3index, + AF_INET, prefixlen, l3index, flags, cmd.tcpm_key, cmd.tcpm_keylen, GFP_KERNEL); return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin6->sin6_addr, - AF_INET6, prefixlen, l3index, + AF_INET6, prefixlen, l3index, flags, cmd.tcpm_key, cmd.tcpm_keylen, GFP_KERNEL); } @@ -1404,7 +1407,7 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff * * across. Shucks. */ tcp_md5_do_add(newsk, (union tcp_md5_addr *)&newsk->sk_v6_daddr, - AF_INET6, 128, l3index, key->key, key->keylen, + AF_INET6, 128, l3index, key->flags, key->key, key->keylen, sk_gfp_mask(sk, GFP_ATOMIC)); } #endif From 78a9cf6143e2d4fb4dd48dde529b24cd5b6bf0e0 Mon Sep 17 00:00:00 2001 From: Leonard Crestez Date: Fri, 15 Oct 2021 10:26:06 +0300 Subject: [PATCH 3/4] selftests: nettest: Add --{force,no}-bind-key-ifindex These options allow explicit control over the TCP_MD5SIG_FLAG_IFINDEX flag instead of always setting it based on binding to an interface. Do this by converting to getopt_long because nettest has too many single-character flags already and getopt_long is widely used in selftests. Signed-off-by: Leonard Crestez Reviewed-by: David Ahern Signed-off-by: David S. Miller --- tools/testing/selftests/net/nettest.c | 28 +++++++++++++++++++++++++-- 1 file changed, 26 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/net/nettest.c b/tools/testing/selftests/net/nettest.c index bd6288302094..b599003eb5ba 100644 --- a/tools/testing/selftests/net/nettest.c +++ b/tools/testing/selftests/net/nettest.c @@ -28,6 +28,7 @@ #include #include #include +#include #include #include @@ -101,6 +102,8 @@ struct sock_args { struct sockaddr_in6 v6; } md5_prefix; unsigned int prefix_len; + /* 0: default, -1: force off, +1: force on */ + int bind_key_ifindex; /* expected addresses and device index for connection */ const char *expected_dev; @@ -271,11 +274,14 @@ static int tcp_md5sig(int sd, void *addr, socklen_t alen, struct sock_args *args } memcpy(&md5sig.tcpm_addr, addr, alen); - if (args->ifindex) { + if ((args->ifindex && args->bind_key_ifindex >= 0) || args->bind_key_ifindex >= 1) { opt = TCP_MD5SIG_EXT; md5sig.tcpm_flags |= TCP_MD5SIG_FLAG_IFINDEX; md5sig.tcpm_ifindex = args->ifindex; + log_msg("TCP_MD5SIG_FLAG_IFINDEX set tcpm_ifindex=%d\n", md5sig.tcpm_ifindex); + } else { + log_msg("TCP_MD5SIG_FLAG_IFINDEX off\n", md5sig.tcpm_ifindex); } rc = setsockopt(sd, IPPROTO_TCP, opt, &md5sig, sizeof(md5sig)); @@ -1822,6 +1828,14 @@ static int ipc_parent(int cpid, int fd, struct sock_args *args) } #define GETOPT_STR "sr:l:c:p:t:g:P:DRn:M:X:m:d:I:BN:O:SCi6xL:0:1:2:3:Fbq" +#define OPT_FORCE_BIND_KEY_IFINDEX 1001 +#define OPT_NO_BIND_KEY_IFINDEX 1002 + +static struct option long_opts[] = { + {"force-bind-key-ifindex", 0, 0, OPT_FORCE_BIND_KEY_IFINDEX}, + {"no-bind-key-ifindex", 0, 0, OPT_NO_BIND_KEY_IFINDEX}, + {0, 0, 0, 0} +}; static void print_usage(char *prog) { @@ -1858,6 +1872,10 @@ static void print_usage(char *prog) " -M password use MD5 sum protection\n" " -X password MD5 password for client mode\n" " -m prefix/len prefix and length to use for MD5 key\n" + " --no-bind-key-ifindex: Force TCP_MD5SIG_FLAG_IFINDEX off\n" + " --force-bind-key-ifindex: Force TCP_MD5SIG_FLAG_IFINDEX on\n" + " (default: only if -I is passed)\n" + "\n" " -g grp multicast group (e.g., 239.1.1.1)\n" " -i interactive mode (default is echo and terminate)\n" "\n" @@ -1893,7 +1911,7 @@ int main(int argc, char *argv[]) * process input args */ - while ((rc = getopt(argc, argv, GETOPT_STR)) != -1) { + while ((rc = getopt_long(argc, argv, GETOPT_STR, long_opts, NULL)) != -1) { switch (rc) { case 'B': both_mode = 1; @@ -1966,6 +1984,12 @@ int main(int argc, char *argv[]) case 'M': args.password = optarg; break; + case OPT_FORCE_BIND_KEY_IFINDEX: + args.bind_key_ifindex = 1; + break; + case OPT_NO_BIND_KEY_IFINDEX: + args.bind_key_ifindex = -1; + break; case 'X': args.client_pw = optarg; break; From 64e4017778bea04a50ed564615339801e02d2d32 Mon Sep 17 00:00:00 2001 From: Leonard Crestez Date: Fri, 15 Oct 2021 10:26:07 +0300 Subject: [PATCH 4/4] selftests: net/fcnal: Test --{force,no}-bind-key-ifindex Test that applications binding listening sockets to VRFs without specifying TCP_MD5SIG_FLAG_IFINDEX will work as expected. This would be broken if __tcp_md5_do_lookup always made a strict comparison on l3index. See this email: https://lore.kernel.org/netdev/209548b5-27d2-2059-f2e9-2148f5a0291b@gmail.com/ Applications using tcp_l3mdev_accept=1 and a single global socket (not bound to any interface) also should have a way to specify keys that are only for the default VRF, this is done by --force-bind-key-ifindex without otherwise binding to a device. Signed-off-by: Leonard Crestez Reviewed-by: David Ahern Signed-off-by: David S. Miller --- tools/testing/selftests/net/fcnal-test.sh | 60 +++++++++++++++++++++++ 1 file changed, 60 insertions(+) diff --git a/tools/testing/selftests/net/fcnal-test.sh b/tools/testing/selftests/net/fcnal-test.sh index 13350cd5c8ac..8e67a252b672 100755 --- a/tools/testing/selftests/net/fcnal-test.sh +++ b/tools/testing/selftests/net/fcnal-test.sh @@ -289,6 +289,12 @@ set_sysctl() run_cmd sysctl -q -w $* } +# get sysctl values in NS-A +get_sysctl() +{ + ${NSA_CMD} sysctl -n $* +} + ################################################################################ # Setup for tests @@ -1003,6 +1009,60 @@ ipv4_tcp_md5() run_cmd nettest -s -I ${NSA_DEV} -M ${MD5_PW} -m ${NS_NET} log_test $? 1 "MD5: VRF: Device must be a VRF - prefix" + test_ipv4_md5_vrf__vrf_server__no_bind_ifindex + test_ipv4_md5_vrf__global_server__bind_ifindex0 +} + +test_ipv4_md5_vrf__vrf_server__no_bind_ifindex() +{ + log_start + show_hint "Simulates applications using VRF without TCP_MD5SIG_FLAG_IFINDEX" + run_cmd nettest -s -I ${VRF} -M ${MD5_PW} -m ${NS_NET} --no-bind-key-ifindex & + sleep 1 + run_cmd_nsb nettest -r ${NSA_IP} -X ${MD5_PW} + log_test $? 0 "MD5: VRF: VRF-bound server, unbound key accepts connection" + + log_start + show_hint "Binding both the socket and the key is not required but it works" + run_cmd nettest -s -I ${VRF} -M ${MD5_PW} -m ${NS_NET} --force-bind-key-ifindex & + sleep 1 + run_cmd_nsb nettest -r ${NSA_IP} -X ${MD5_PW} + log_test $? 0 "MD5: VRF: VRF-bound server, bound key accepts connection" +} + +test_ipv4_md5_vrf__global_server__bind_ifindex0() +{ + # This particular test needs tcp_l3mdev_accept=1 for Global server to accept VRF connections + local old_tcp_l3mdev_accept + old_tcp_l3mdev_accept=$(get_sysctl net.ipv4.tcp_l3mdev_accept) + set_sysctl net.ipv4.tcp_l3mdev_accept=1 + + log_start + run_cmd nettest -s -M ${MD5_PW} -m ${NS_NET} --force-bind-key-ifindex & + sleep 1 + run_cmd_nsb nettest -r ${NSA_IP} -X ${MD5_PW} + log_test $? 2 "MD5: VRF: Global server, Key bound to ifindex=0 rejects VRF connection" + + log_start + run_cmd nettest -s -M ${MD5_PW} -m ${NS_NET} --force-bind-key-ifindex & + sleep 1 + run_cmd_nsc nettest -r ${NSA_IP} -X ${MD5_PW} + log_test $? 0 "MD5: VRF: Global server, key bound to ifindex=0 accepts non-VRF connection" + log_start + + run_cmd nettest -s -M ${MD5_PW} -m ${NS_NET} --no-bind-key-ifindex & + sleep 1 + run_cmd_nsb nettest -r ${NSA_IP} -X ${MD5_PW} + log_test $? 0 "MD5: VRF: Global server, key not bound to ifindex accepts VRF connection" + + log_start + run_cmd nettest -s -M ${MD5_PW} -m ${NS_NET} --no-bind-key-ifindex & + sleep 1 + run_cmd_nsc nettest -r ${NSA_IP} -X ${MD5_PW} + log_test $? 0 "MD5: VRF: Global server, key not bound to ifindex accepts non-VRF connection" + + # restore value + set_sysctl net.ipv4.tcp_l3mdev_accept="$old_tcp_l3mdev_accept" } ipv4_tcp_novrf()