bgpd: RFC 5082 Generalized TTL Security Mechanism support
* bgpd: Add support for RFC 5082 GTSM, which allows the TTL field to be used
to verify that incoming packets have been sent from neighbours no more
than X IP hops away. In other words, this allows packets that were sent from
further away (i.e. not by the neighbour with known distance, and so possibly
a miscreant) to be filtered out.
* lib/sockunion.{c,h}: (sockopt_minttl) new function, to set a minimum TTL
using the IP_MINTTL socket opt.
* bgpd.h: (BGP_ERR_NO_EBGP_MULTIHOP_WITH_TTLHACK) define for command
error for minttl.
(struct peer) add a config variable, to store the configured minttl.
(peer_ttl_security_hops_{set,unset}) configuration handlers
* bgpd.c: (peer_group_get) init gtsm_hops
(peer_ebgp_multihop_{un,}set) check for conflicts with GTSM. Multihop and
GTSM can't both be active for a peer at the same time.
(peer_ttl_security_hops_set) set minttl, taking care to avoid conflicts with
ebgp_multihop.
(bgp_config_write_peer) write out minttl as "neighbor .. ttl-security hops X".
* bgp_vty.c: (bgp_vty_return) message for
BGP_ERR_NO_EBGP_MULTIHOP_WITH_TTLHACK
(peer_ebgp_multihop_{un,}set_vty)
* bgp_network.c: (bgp_accept) set minttl on accepted sockets if appropriate.
(bgp_connect) ditto for outbound.
diff --git a/bgpd/bgp_network.c b/bgpd/bgp_network.c
index 4c79aa6..502f567 100644
--- a/bgpd/bgp_network.c
+++ b/bgpd/bgp_network.c
@@ -173,8 +173,11 @@
}
/* In case of peer is EBGP, we should set TTL for this connection. */
- if (peer_sort (peer1) == BGP_PEER_EBGP)
+ if (peer_sort (peer1) == BGP_PEER_EBGP) {
sockopt_ttl (peer1->su.sa.sa_family, bgp_sock, peer1->ttl);
+ if (peer1->gtsm_hops)
+ sockopt_minttl (peer1->su.sa.sa_family, bgp_sock, MAXTTL + 1 - peer1->gtsm_hops);
+ }
/* Make dummy peer until read Open packet. */
if (BGP_DEBUG (events, EVENTS))
@@ -314,8 +317,11 @@
return -1;
/* If we can get socket for the peer, adjest TTL and make connection. */
- if (peer_sort (peer) == BGP_PEER_EBGP)
+ if (peer_sort (peer) == BGP_PEER_EBGP) {
sockopt_ttl (peer->su.sa.sa_family, peer->fd, peer->ttl);
+ if (peer->gtsm_hops)
+ sockopt_minttl (peer->su.sa.sa_family, peer->fd, MAXTTL + 1 - peer->gtsm_hops);
+ }
sockopt_reuseaddr (peer->fd);
sockopt_reuseport (peer->fd);
@@ -462,7 +468,10 @@
zlog_err ("socket: %s", safe_strerror (errno));
continue;
}
-
+
+ /* if we intend to implement ttl-security, this socket needs ttl=255 */
+ sockopt_ttl (ainfo->ai_family, sock, MAXTTL);
+
ret = bgp_listener (sock, ainfo->ai_addr, ainfo->ai_addrlen);
if (ret == 0)
++count;
@@ -495,6 +504,9 @@
return sock;
}
+ /* if we intend to implement ttl-security, this socket needs ttl=255 */
+ sockopt_ttl (AF_INET, sock, MAXTTL);
+
memset (&sin, 0, sizeof (struct sockaddr_in));
sin.sin_family = AF_INET;
sin.sin_port = htons (port);
diff --git a/bgpd/bgp_vty.c b/bgpd/bgp_vty.c
index 1f93eea..e1c47f4 100644
--- a/bgpd/bgp_vty.c
+++ b/bgpd/bgp_vty.c
@@ -213,6 +213,9 @@
case BGP_ERR_TCPSIG_FAILED:
str = "Error while applying TCP-Sig to session(s)";
break;
+ case BGP_ERR_NO_EBGP_MULTIHOP_WITH_TTLHACK:
+ str = "ebgp-multihop and ttl-security cannot be configured together";
+ break;
}
if (str)
{
@@ -2626,6 +2629,7 @@
{
struct peer *peer;
unsigned int ttl;
+ int ret;
peer = peer_and_group_lookup_vty (vty, ip_str);
if (! peer)
@@ -2636,23 +2640,24 @@
else
VTY_GET_INTEGER_RANGE ("TTL", ttl, ttl_str, 1, 255);
- peer_ebgp_multihop_set (peer, ttl);
-
- return CMD_SUCCESS;
+ ret = peer_ebgp_multihop_set (peer, ttl);
+
+ return bgp_vty_return (vty, ret);
}
static int
peer_ebgp_multihop_unset_vty (struct vty *vty, const char *ip_str)
{
struct peer *peer;
+ int ret;
peer = peer_and_group_lookup_vty (vty, ip_str);
if (! peer)
return CMD_WARNING;
- peer_ebgp_multihop_unset (peer);
-
- return CMD_SUCCESS;
+ ret = peer_ebgp_multihop_unset (peer);
+
+ return bgp_vty_return (vty, ret);
}
/* neighbor ebgp-multihop. */
@@ -3954,6 +3959,47 @@
return bgp_vty_return (vty, ret);
}
+DEFUN (neighbor_ttl_security,
+ neighbor_ttl_security_cmd,
+ NEIGHBOR_CMD2 "ttl-security hops <1-254>",
+ NEIGHBOR_STR
+ NEIGHBOR_ADDR_STR2
+ "Specify the maximum number of hops to the BGP peer\n")
+{
+ struct peer *peer;
+ int ret, gtsm_hops;
+
+ peer = peer_and_group_lookup_vty (vty, argv[0]);
+ if (! peer)
+ return CMD_WARNING;
+
+ VTY_GET_INTEGER_RANGE ("", gtsm_hops, argv[1], 1, 254);
+
+ ret = peer_ttl_security_hops_set (peer, gtsm_hops);
+
+ return bgp_vty_return (vty, ret);
+}
+
+DEFUN (no_neighbor_ttl_security,
+ no_neighbor_ttl_security_cmd,
+ NO_NEIGHBOR_CMD2 "ttl-security hops <1-254>",
+ NO_STR
+ NEIGHBOR_STR
+ NEIGHBOR_ADDR_STR2
+ "Specify the maximum number of hops to the BGP peer\n")
+{
+ struct peer *peer;
+ int ret;
+
+ peer = peer_and_group_lookup_vty (vty, argv[0]);
+ if (! peer)
+ return CMD_WARNING;
+
+ ret = peer_ttl_security_hops_unset (peer);
+
+ return bgp_vty_return (vty, ret);
+}
+
/* Address family configuration. */
DEFUN (address_family_ipv4,
address_family_ipv4_cmd,
@@ -10060,6 +10106,10 @@
install_element (BGP_IPV6_NODE, &no_bgp_redistribute_ipv6_metric_rmap_cmd);
#endif /* HAVE_IPV6 */
+ /* ttl_security commands */
+ install_element (BGP_NODE, &neighbor_ttl_security_cmd);
+ install_element (BGP_NODE, &no_neighbor_ttl_security_cmd);
+
/* "show bgp memory" commands. */
install_element (VIEW_NODE, &show_bgp_memory_cmd);
install_element (RESTRICTED_NODE, &show_bgp_memory_cmd);
diff --git a/bgpd/bgpd.c b/bgpd/bgpd.c
index 882fe37..cc0ea8d 100644
--- a/bgpd/bgpd.c
+++ b/bgpd/bgpd.c
@@ -1379,6 +1379,7 @@
group->conf->group = group;
group->conf->as = 0;
group->conf->ttl = 1;
+ group->conf->gtsm_hops = 0;
group->conf->v_routeadv = BGP_DEFAULT_EBGP_ROUTEADV;
UNSET_FLAG (group->conf->config, PEER_CONFIG_TIMER);
UNSET_FLAG (group->conf->config, PEER_CONFIG_CONNECT);
@@ -1416,6 +1417,9 @@
/* TTL */
peer->ttl = conf->ttl;
+ /* GTSM hops */
+ peer->gtsm_hops = conf->gtsm_hops;
+
/* Weight */
peer->weight = conf->weight;
@@ -2663,10 +2667,36 @@
{
struct peer_group *group;
struct listnode *node, *nnode;
+ struct peer *peer1;
if (peer_sort (peer) == BGP_PEER_IBGP)
return 0;
+ /* see comment in peer_ttl_security_hops_set() */
+ if (ttl != MAXTTL)
+ {
+ if (CHECK_FLAG (peer->sflags, PEER_STATUS_GROUP))
+ {
+ group = peer->group;
+ if (group->conf->gtsm_hops != 0)
+ return BGP_ERR_NO_EBGP_MULTIHOP_WITH_TTLHACK;
+
+ for (ALL_LIST_ELEMENTS (group->peer, node, nnode, peer1))
+ {
+ if (peer_sort (peer1) == BGP_PEER_IBGP)
+ continue;
+
+ if (peer1->gtsm_hops != 0)
+ return BGP_ERR_NO_EBGP_MULTIHOP_WITH_TTLHACK;
+ }
+ }
+ else
+ {
+ if (peer->gtsm_hops != 0)
+ return BGP_ERR_NO_EBGP_MULTIHOP_WITH_TTLHACK;
+ }
+ }
+
peer->ttl = ttl;
if (! CHECK_FLAG (peer->sflags, PEER_STATUS_GROUP))
@@ -2700,6 +2730,9 @@
if (peer_sort (peer) == BGP_PEER_IBGP)
return 0;
+ if (peer->gtsm_hops != 0 && peer->ttl != MAXTTL)
+ return BGP_ERR_NO_EBGP_MULTIHOP_WITH_TTLHACK;
+
if (peer_group_active (peer))
peer->ttl = peer->group->conf->ttl;
else
@@ -4331,6 +4364,121 @@
return 0;
}
+/* Set # of hops between us and BGP peer. */
+int
+peer_ttl_security_hops_set (struct peer *peer, int gtsm_hops)
+{
+ struct peer_group *group;
+ struct listnode *node, *nnode;
+ struct peer *peer1;
+ int ret;
+
+ zlog_debug ("peer_ttl_security_hops_set: set gtsm_hops to %d for %s", gtsm_hops, peer->host);
+
+ if (peer_sort (peer) == BGP_PEER_IBGP)
+ return 0;
+
+ /* We cannot configure ttl-security hops when ebgp-multihop is already
+ set. For non peer-groups, the check is simple. For peer-groups, it's
+ slightly messy, because we need to check both the peer-group structure
+ and all peer-group members for any trace of ebgp-multihop configuration
+ before actually applying the ttl-security rules. Cisco really made a
+ mess of this configuration parameter, and OpenBGPD got it right.
+ */
+
+ if (CHECK_FLAG (peer->sflags, PEER_STATUS_GROUP))
+ {
+ group = peer->group;
+ if (group->conf->ttl != 1)
+ return BGP_ERR_NO_EBGP_MULTIHOP_WITH_TTLHACK;
+
+ for (ALL_LIST_ELEMENTS (group->peer, node, nnode, peer1))
+ {
+ if (peer_sort (peer1) == BGP_PEER_IBGP)
+ continue;
+
+ if (peer1->ttl != 1)
+ return BGP_ERR_NO_EBGP_MULTIHOP_WITH_TTLHACK;
+ }
+ }
+ else
+ {
+ if (peer->ttl != 1)
+ return BGP_ERR_NO_EBGP_MULTIHOP_WITH_TTLHACK;
+ }
+
+ peer->gtsm_hops = gtsm_hops;
+
+ /* specify MAXTTL on outgoing packets */
+ ret = peer_ebgp_multihop_set (peer, MAXTTL);
+ if (ret != 0)
+ return ret;
+
+ if (! CHECK_FLAG (peer->sflags, PEER_STATUS_GROUP))
+ {
+ if (peer->fd >= 0 && peer_sort (peer) != BGP_PEER_IBGP)
+ sockopt_minttl (peer->su.sa.sa_family, peer->fd, MAXTTL + 1 - gtsm_hops);
+ }
+ else
+ {
+ group = peer->group;
+ for (ALL_LIST_ELEMENTS (group->peer, node, nnode, peer))
+ {
+ if (peer_sort (peer) == BGP_PEER_IBGP)
+ continue;
+
+ peer->gtsm_hops = group->conf->gtsm_hops;
+
+ if (peer->fd >= 0 && peer->gtsm_hops != 0)
+ sockopt_minttl (peer->su.sa.sa_family, peer->fd, MAXTTL + 1 - peer->gtsm_hops);
+ }
+ }
+
+ return 0;
+}
+
+int
+peer_ttl_security_hops_unset (struct peer *peer)
+{
+ struct peer_group *group;
+ struct listnode *node, *nnode;
+ struct peer *opeer;
+
+ zlog_debug ("peer_ttl_security_hops_unset: set gtsm_hops to zero for %s", peer->host);
+
+ if (peer_sort (peer) == BGP_PEER_IBGP)
+ return 0;
+
+ /* if a peer-group member, then reset to peer-group default rather than 0 */
+ if (peer_group_active (peer))
+ peer->gtsm_hops = peer->group->conf->gtsm_hops;
+ else
+ peer->gtsm_hops = 0;
+
+ opeer = peer;
+ if (! CHECK_FLAG (peer->sflags, PEER_STATUS_GROUP))
+ {
+ if (peer->fd >= 0 && peer_sort (peer) != BGP_PEER_IBGP)
+ sockopt_minttl (peer->su.sa.sa_family, peer->fd, 0);
+ }
+ else
+ {
+ group = peer->group;
+ for (ALL_LIST_ELEMENTS (group->peer, node, nnode, peer))
+ {
+ if (peer_sort (peer) == BGP_PEER_IBGP)
+ continue;
+
+ peer->gtsm_hops = 0;
+
+ if (peer->fd >= 0)
+ sockopt_minttl (peer->su.sa.sa_family, peer->fd, 0);
+ }
+ }
+
+ return peer_ebgp_multihop_unset (opeer);
+}
+
int
peer_clear (struct peer *peer)
{
@@ -4635,12 +4783,19 @@
vty_out (vty, " neighbor %s passive%s", addr, VTY_NEWLINE);
/* EBGP multihop. */
- if (peer_sort (peer) != BGP_PEER_IBGP && peer->ttl != 1)
+ if (peer_sort (peer) != BGP_PEER_IBGP && peer->ttl != 1 &&
+ !(peer->gtsm_hops != 0 && peer->ttl == MAXTTL))
if (! peer_group_active (peer) ||
g_peer->ttl != peer->ttl)
vty_out (vty, " neighbor %s ebgp-multihop %d%s", addr, peer->ttl,
VTY_NEWLINE);
+ /* ttl-security hops */
+ if (peer_sort (peer) != BGP_PEER_IBGP && peer->gtsm_hops != 0)
+ if (! peer_group_active (peer) || g_peer->gtsm_hops != peer->gtsm_hops)
+ vty_out (vty, " neighbor %s ttl-security hops %d%s", addr,
+ peer->gtsm_hops, VTY_NEWLINE);
+
/* disable-connected-check. */
if (CHECK_FLAG (peer->flags, PEER_FLAG_DISABLE_CONNECTED_CHECK))
if (! peer_group_active (peer) ||
diff --git a/bgpd/bgpd.h b/bgpd/bgpd.h
index a5afaed..39cdf8e 100644
--- a/bgpd/bgpd.h
+++ b/bgpd/bgpd.h
@@ -303,6 +303,7 @@
/* Peer information */
int fd; /* File descriptor */
int ttl; /* TTL of TCP connection to the peer. */
+ int gtsm_hops; /* minimum hopcount to peer */
char *desc; /* Description of the peer. */
unsigned short port; /* Destination port for peer */
char *host; /* Printable address of the peer. */
@@ -800,7 +801,8 @@
#define BGP_ERR_LOCAL_AS_ALLOWED_ONLY_FOR_EBGP -27
#define BGP_ERR_CANNOT_HAVE_LOCAL_AS_SAME_AS -28
#define BGP_ERR_TCPSIG_FAILED -29
-#define BGP_ERR_MAX -30
+#define BGP_ERR_NO_EBGP_MULTIHOP_WITH_TTLHACK -30
+#define BGP_ERR_MAX -31
extern struct bgp_master *bm;
@@ -953,4 +955,7 @@
extern int peer_clear (struct peer *);
extern int peer_clear_soft (struct peer *, afi_t, safi_t, enum bgp_clear_type);
+extern int peer_ttl_security_hops_set (struct peer *, int);
+extern int peer_ttl_security_hops_unset (struct peer *);
+
#endif /* _QUAGGA_BGPD_H */
diff --git a/lib/sockunion.c b/lib/sockunion.c
index f6c060f..a32809c 100644
--- a/lib/sockunion.c
+++ b/lib/sockunion.c
@@ -537,6 +537,28 @@
#endif
}
+int
+sockopt_minttl (int family, int sock, int minttl)
+{
+ int ret;
+
+ zlog_debug ("sockopt_minttl: set minttl to %d", minttl);
+
+#ifdef IP_MINTTL
+ ret = setsockopt (sock, IPPROTO_IP, IP_MINTTL, &minttl, sizeof(minttl));
+#else
+ ret = -1;
+ errno = EOPNOTSUPP;
+#endif /* IP_MINTTL */
+ if (ret < 0)
+ {
+ zlog (NULL, LOG_WARNING, "can't set sockopt IP_MINTTL to %d on socket %d: %s", minttl, sock, safe_strerror (errno));
+ return -1;
+ }
+
+ return 0;
+}
+
/* If same family and same prefix return 1. */
int
sockunion_same (union sockunion *su1, union sockunion *su2)
diff --git a/lib/sockunion.h b/lib/sockunion.h
index 91bfbc7..0ee2d63 100644
--- a/lib/sockunion.h
+++ b/lib/sockunion.h
@@ -102,6 +102,7 @@
extern int sockunion_bind (int sock, union sockunion *,
unsigned short, union sockunion *);
extern int sockopt_ttl (int family, int sock, int ttl);
+extern int sockopt_minttl (int family, int sock, int minttl);
extern int sockopt_cork (int sock, int onoff);
extern int sockunion_socket (union sockunion *su);
extern const char *inet_sutop (union sockunion *su, char *str);