This is a parallel feature to tcp_md5sig.tcpm_ifindex support and allows applications to server multiple VRFs with a single socket.
The ifindex argument must be the ifindex of a VRF device and must match exactly, keys with ifindex == 0 (outside of VRF) will not match for connections inside a VRF.
Keys without the TCP_AUTHOPT_KEY_IFINDEX will ignore ifindex and match both inside and outside VRF.
Signed-off-by: Leonard Crestez cdleonard@gmail.com --- Documentation/networking/tcp_authopt.rst | 1 + include/net/tcp_authopt.h | 2 + include/uapi/linux/tcp.h | 11 ++++ net/ipv4/tcp_authopt.c | 71 ++++++++++++++++++++++-- 4 files changed, 80 insertions(+), 5 deletions(-)
diff --git a/Documentation/networking/tcp_authopt.rst b/Documentation/networking/tcp_authopt.rst index f29fdea7769f..f681d2221ce3 100644 --- a/Documentation/networking/tcp_authopt.rst +++ b/Documentation/networking/tcp_authopt.rst @@ -37,10 +37,11 @@ expand over time by increasing the size of `struct tcp_authopt_key` and adding new flags.
* Address binding is optional, by default keys match all addresses * Local address is ignored, matching is done by remote address * Ports are ignored + * It is possible to match a specific VRF by l3index (default is to ignore)
RFC5925 requires that key ids do not overlap when tcp identifiers (addr/port) overlap. This is not enforced by linux, configuring ambiguous keys will result in packet drops and lost connections.
diff --git a/include/net/tcp_authopt.h b/include/net/tcp_authopt.h index 3d03fbb186ef..800fde277239 100644 --- a/include/net/tcp_authopt.h +++ b/include/net/tcp_authopt.h @@ -45,10 +45,12 @@ struct tcp_authopt_key_info { u8 alg_id; /** @keylen: Same as &tcp_authopt_key.keylen */ u8 keylen; /** @key: Same as &tcp_authopt_key.key */ u8 key[TCP_AUTHOPT_MAXKEYLEN]; + /** @l3index: Same as &tcp_authopt_key.ifindex */ + int l3index; /** @addr: Same as &tcp_authopt_key.addr */ struct sockaddr_storage addr; /** @alg: Algorithm implementation matching alg_id */ struct tcp_authopt_alg_imp *alg; }; diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h index e02176390519..a7f5f918ed5a 100644 --- a/include/uapi/linux/tcp.h +++ b/include/uapi/linux/tcp.h @@ -400,15 +400,17 @@ struct tcp_authopt { * enum tcp_authopt_key_flag - flags for `tcp_authopt.flags` * * @TCP_AUTHOPT_KEY_DEL: Delete the key and ignore non-id fields * @TCP_AUTHOPT_KEY_EXCLUDE_OPTS: Exclude TCP options from signature * @TCP_AUTHOPT_KEY_ADDR_BIND: Key only valid for `tcp_authopt.addr` + * @TCP_AUTHOPT_KEY_IFINDEX: Key only valid for `tcp_authopt.ifindex` */ enum tcp_authopt_key_flag { TCP_AUTHOPT_KEY_DEL = (1 << 0), TCP_AUTHOPT_KEY_EXCLUDE_OPTS = (1 << 1), TCP_AUTHOPT_KEY_ADDR_BIND = (1 << 2), + TCP_AUTHOPT_KEY_IFINDEX = (1 << 3), };
/** * enum tcp_authopt_alg - Algorithms for TCP Authentication Option */ @@ -450,10 +452,19 @@ struct tcp_authopt_key { * @addr: Key is only valid for this address * * Ignored unless TCP_AUTHOPT_KEY_ADDR_BIND flag is set */ struct __kernel_sockaddr_storage addr; + /** + * @ifindex: ifindex of vrf (l3mdev_master) interface + * + * If the TCP_AUTHOPT_KEY_IFINDEX flag is set then key only applies for + * connections through this interface. Interface must be an vrf master. + * + * This is similar to `tcp_msg5sig.tcpm_ifindex` + */ + int ifindex; };
/* setsockopt(fd, IPPROTO_TCP, TCP_ZEROCOPY_RECEIVE, ...) */
#define TCP_RECEIVE_ZEROCOPY_FLAG_TLB_CLEAN_HINT 0x1 diff --git a/net/ipv4/tcp_authopt.c b/net/ipv4/tcp_authopt.c index f0d7a7facfb9..f3e244d036c3 100644 --- a/net/ipv4/tcp_authopt.c +++ b/net/ipv4/tcp_authopt.c @@ -1,8 +1,9 @@ // SPDX-License-Identifier: GPL-2.0-or-later
#include <net/tcp_authopt.h> +#include <net/ip.h> #include <net/ipv6.h> #include <net/tcp.h> #include <linux/kref.h> #include <crypto/hash.h>
@@ -261,10 +262,14 @@ static bool tcp_authopt_key_match_exact(struct tcp_authopt_key_info *info, { if (info->send_id != key->send_id) return false; if (info->recv_id != key->recv_id) return false; + if ((info->flags & TCP_AUTHOPT_KEY_IFINDEX) != (key->flags & TCP_AUTHOPT_KEY_IFINDEX)) + return false; + if ((info->flags & TCP_AUTHOPT_KEY_IFINDEX) && info->l3index != key->ifindex) + return false; if ((info->flags & TCP_AUTHOPT_KEY_ADDR_BIND) != (key->flags & TCP_AUTHOPT_KEY_ADDR_BIND)) return false; if (info->flags & TCP_AUTHOPT_KEY_ADDR_BIND) if (!ipvx_addr_match(&info->addr, &key->addr)) return false; @@ -328,26 +333,49 @@ static struct tcp_authopt_key_info *tcp_authopt_key_lookup_exact(const struct so return key_info;
return NULL; }
+static bool better_key_match(struct tcp_authopt_key_info *old, struct tcp_authopt_key_info *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 false; +} + static struct tcp_authopt_key_info *tcp_authopt_lookup_send(struct netns_tcp_authopt *net, const struct sock *addr_sk, int send_id) { struct tcp_authopt_key_info *result = NULL; struct tcp_authopt_key_info *key; + int l3index = -1;
hlist_for_each_entry_rcu(key, &net->head, node, 0) { if (send_id >= 0 && key->send_id != send_id) continue; if (key->flags & TCP_AUTHOPT_KEY_ADDR_BIND) if (!tcp_authopt_key_match_sk_addr(key, addr_sk)) continue; - if (result && net_ratelimit()) - pr_warn("ambiguous tcp authentication keys configured for send\n"); - result = key; + if (key->flags & TCP_AUTHOPT_KEY_IFINDEX) { + if (l3index < 0) + l3index = l3mdev_master_ifindex_by_index(sock_net(addr_sk), + addr_sk->sk_bound_dev_if); + if (l3index != key->l3index) + continue; + } + if (better_key_match(result, key)) + result = key; + else if (result) + net_warn_ratelimited("ambiguous tcp authentication keys configured for send\n"); }
return result; }
@@ -578,19 +606,21 @@ int tcp_get_authopt_val(struct sock *sk, struct tcp_authopt *opt) }
#define TCP_AUTHOPT_KEY_KNOWN_FLAGS ( \ TCP_AUTHOPT_KEY_DEL | \ TCP_AUTHOPT_KEY_EXCLUDE_OPTS | \ - TCP_AUTHOPT_KEY_ADDR_BIND) + TCP_AUTHOPT_KEY_ADDR_BIND | \ + TCP_AUTHOPT_KEY_IFINDEX)
int tcp_set_authopt_key(struct sock *sk, sockptr_t optval, unsigned int optlen) { struct tcp_authopt_key opt; struct tcp_authopt_info *info; struct tcp_authopt_key_info *key_info, *old_key_info; struct netns_tcp_authopt *net = sock_net_tcp_authopt(sk); struct tcp_authopt_alg_imp *alg; + int l3index = 0; int err;
sock_owned_by_me(sk); err = check_sysctl_tcp_authopt(); if (err) @@ -641,10 +671,24 @@ int tcp_set_authopt_key(struct sock *sk, sockptr_t optval, unsigned int optlen) return -EINVAL; err = tcp_authopt_alg_require(alg); if (err) return err;
+ /* check ifindex is valid (zero is always valid) */ + if (opt.flags & TCP_AUTHOPT_KEY_IFINDEX && opt.ifindex) { + struct net_device *dev; + + rcu_read_lock(); + dev = dev_get_by_index_rcu(sock_net(sk), opt.ifindex); + if (dev && netif_is_l3_master(dev)) + l3index = dev->ifindex; + rcu_read_unlock(); + + if (!l3index) + return -EINVAL; + } + key_info = sock_kmalloc(sk, sizeof(*key_info), GFP_KERNEL | __GFP_ZERO); if (!key_info) return -ENOMEM; mutex_lock(&net->mutex); kref_init(&key_info->ref); @@ -660,10 +704,11 @@ int tcp_set_authopt_key(struct sock *sk, sockptr_t optval, unsigned int optlen) key_info->alg_id = opt.alg; key_info->alg = alg; key_info->keylen = opt.keylen; memcpy(key_info->key, opt.key, opt.keylen); memcpy(&key_info->addr, &opt.addr, sizeof(key_info->addr)); + key_info->l3index = l3index; hlist_add_head_rcu(&key_info->node, &net->head); mutex_unlock(&net->mutex);
return 0; } @@ -1423,21 +1468,37 @@ static struct tcp_authopt_key_info *tcp_authopt_lookup_recv(struct sock *sk, int recv_id, bool *anykey) { struct tcp_authopt_key_info *result = NULL; struct tcp_authopt_key_info *key; + int l3index = -1;
*anykey = false; /* multiple matches will cause occasional failures */ hlist_for_each_entry_rcu(key, &net->head, node, 0) { if (key->flags & TCP_AUTHOPT_KEY_ADDR_BIND && !tcp_authopt_key_match_skb_addr(key, skb)) continue; + if (key->flags & TCP_AUTHOPT_KEY_IFINDEX) { + if (l3index < 0) { + if (skb->protocol == htons(ETH_P_IP)) { + l3index = inet_sdif(skb) ? inet_iif(skb) : 0; + } else if (skb->protocol == htons(ETH_P_IPV6)) { + l3index = inet6_sdif(skb) ? inet6_iif(skb) : 0; + } else { + WARN_ONCE(1, "unexpected skb->protocol=%x", skb->protocol); + continue; + } + } + + if (l3index != key->l3index) + continue; + } *anykey = true; if (recv_id >= 0 && key->recv_id != recv_id) continue; - if (!result) + if (better_key_match(result, key)) result = key; else if (result) net_warn_ratelimited("ambiguous tcp authentication keys configured for recv\n"); }