frr: T5557: use treat-as-withdraw for tunnel encapsulation attribute CVE-2023-38802

Before this path we used session reset method, which is discouraged by rfc7606.
Handle this as rfc requires.

This addes the fix submitted as https://github.com/FRRouting/frr/pull/14381
upstream. Using VyOS patch until the above mentioned PR is merged.

1 files changed, 134 insertions, 0 deletions

diff --git a/packages/frr/patches/0004-bgpd-Use-treat-as-withdraw-for-tunnel-encapsulation-.patch b/packages/frr/patches/0004-bgpd-Use-treat-as-withdraw-for-tunnel-encapsulation-.patch
new file mode 100644
index 00000000..a6d824c4
--- /dev/null
+++ b/packages/frr/patches/0004-bgpd-Use-treat-as-withdraw-for-tunnel-encapsulation-.patch
@@ -0,0 +1,134 @@
+From a3337f1bd534d1d2b47b149a14418c5d93d341e3 Mon Sep 17 00:00:00 2001
+From: Donatas Abraitis <donatas@opensourcerouting.org>
+Date: Thu, 13 Jul 2023 22:32:03 +0300
+Subject: [PATCH] bgpd: Use treat-as-withdraw for tunnel encapsulation
+ attribute
+
+Before this path we used session reset method, which is discouraged by rfc7606.
+
+Handle this as rfc requires.
+
+Signed-off-by: Donatas Abraitis <donatas@opensourcerouting.org>
+Signed-off-by: Christian Breunig <christian@breunig.cc>
+
+(cherry picked from commit bcb6b58d9530173df41d3a3cbc4c600ee0b4b186)
+---
+ bgpd/bgp_attr.c | 61 ++++++++++++++++++++-----------------------------
+ 1 file changed, 25 insertions(+), 36 deletions(-)
+
+diff --git a/bgpd/bgp_attr.c b/bgpd/bgp_attr.c
+index f5e54267d..4bc28fe23 100644
+--- a/bgpd/bgp_attr.c
++++ b/bgpd/bgp_attr.c
+@@ -1225,6 +1225,7 @@ bgp_attr_malformed(struct bgp_attr_parser_args *args, uint8_t subcode,
+ 	case BGP_ATTR_LARGE_COMMUNITIES:
+ 	case BGP_ATTR_ORIGINATOR_ID:
+ 	case BGP_ATTR_CLUSTER_LIST:
++	case BGP_ATTR_ENCAP:
+ 		return BGP_ATTR_PARSE_WITHDRAW;
+ 	case BGP_ATTR_MP_REACH_NLRI:
+ 	case BGP_ATTR_MP_UNREACH_NLRI:
+@@ -2320,26 +2321,21 @@ bgp_attr_ipv6_ext_communities(struct bgp_attr_parser_args *args)
+ }
+ 
+ /* Parse Tunnel Encap attribute in an UPDATE */
+-static int bgp_attr_encap(uint8_t type, struct peer *peer, /* IN */
+-			  bgp_size_t length, /* IN: attr's length field */
+-			  struct attr *attr, /* IN: caller already allocated */
+-			  uint8_t flag,      /* IN: attr's flags field */
+-			  uint8_t *startp)
++static int bgp_attr_encap(struct bgp_attr_parser_args *args)
+ {
+-	bgp_size_t total;
+ 	uint16_t tunneltype = 0;
+-
+-	total = length + (CHECK_FLAG(flag, BGP_ATTR_FLAG_EXTLEN) ? 4 : 3);
++	struct peer *const peer = args->peer;
++	struct attr *const attr = args->attr;
++	bgp_size_t length = args->length;
++	uint8_t type = args->type;
++	uint8_t flag = args->flags;
+ 
+ 	if (!CHECK_FLAG(flag, BGP_ATTR_FLAG_TRANS)
+ 	    || !CHECK_FLAG(flag, BGP_ATTR_FLAG_OPTIONAL)) {
+-		zlog_info(
+-			"Tunnel Encap attribute flag isn't optional and transitive %d",
+-			flag);
+-		bgp_notify_send_with_data(peer, BGP_NOTIFY_UPDATE_ERR,
+-					  BGP_NOTIFY_UPDATE_ATTR_FLAG_ERR,
+-					  startp, total);
+-		return -1;
++		zlog_err("Tunnel Encap attribute flag isn't optional and transitive %d",
++			 flag);
++		return bgp_attr_malformed(args, BGP_NOTIFY_UPDATE_OPT_ATTR_ERR,
++					  args->total);
+ 	}
+ 
+ 	if (BGP_ATTR_ENCAP == type) {
+@@ -2347,12 +2343,11 @@ static int bgp_attr_encap(uint8_t type, struct peer *peer, /* IN */
+ 		uint16_t tlv_length;
+ 
+ 		if (length < 4) {
+-			zlog_info(
++			zlog_err(
+ 				"Tunnel Encap attribute not long enough to contain outer T,L");
+-			bgp_notify_send_with_data(
+-				peer, BGP_NOTIFY_UPDATE_ERR,
+-				BGP_NOTIFY_UPDATE_OPT_ATTR_ERR, startp, total);
+-			return -1;
++			return bgp_attr_malformed(args,
++						  BGP_NOTIFY_UPDATE_OPT_ATTR_ERR,
++						  args->total);
+ 		}
+ 		tunneltype = stream_getw(BGP_INPUT(peer));
+ 		tlv_length = stream_getw(BGP_INPUT(peer));
+@@ -2382,13 +2377,11 @@ static int bgp_attr_encap(uint8_t type, struct peer *peer, /* IN */
+ 		}
+ 
+ 		if (sublength > length) {
+-			zlog_info(
+-				"Tunnel Encap attribute sub-tlv length %d exceeds remaining length %d",
+-				sublength, length);
+-			bgp_notify_send_with_data(
+-				peer, BGP_NOTIFY_UPDATE_ERR,
+-				BGP_NOTIFY_UPDATE_OPT_ATTR_ERR, startp, total);
+-			return -1;
++			zlog_err("Tunnel Encap attribute sub-tlv length %d exceeds remaining length %d",
++				 sublength, length);
++			return bgp_attr_malformed(args,
++						  BGP_NOTIFY_UPDATE_OPT_ATTR_ERR,
++						  args->total);
+ 		}
+ 
+ 		/* alloc and copy sub-tlv */
+@@ -2434,13 +2427,10 @@ static int bgp_attr_encap(uint8_t type, struct peer *peer, /* IN */
+ 
+ 	if (length) {
+ 		/* spurious leftover data */
+-		zlog_info(
+-			"Tunnel Encap attribute length is bad: %d leftover octets",
+-			length);
+-		bgp_notify_send_with_data(peer, BGP_NOTIFY_UPDATE_ERR,
+-					  BGP_NOTIFY_UPDATE_OPT_ATTR_ERR,
+-					  startp, total);
+-		return -1;
++		zlog_err("Tunnel Encap attribute length is bad: %d leftover octets",
++			 length);
++		return bgp_attr_malformed(args, BGP_NOTIFY_UPDATE_OPT_ATTR_ERR,
++					  args->total);
+ 	}
+ 
+ 	return 0;
+@@ -3128,8 +3118,7 @@ bgp_attr_parse_ret_t bgp_attr_parse(struct peer *peer, struct attr *attr,
+ 		case BGP_ATTR_VNC:
+ #endif
+ 		case BGP_ATTR_ENCAP:
+-			ret = bgp_attr_encap(type, peer, length, attr, flag,
+-					     startp);
++			ret = bgp_attr_encap(&attr_args);
+ 			break;
+ 		case BGP_ATTR_PREFIX_SID:
+ 			ret = bgp_attr_prefix_sid(&attr_args);
+-- 
+2.39.2
+