From 7893fecf7d24acf9c365c3982152ec6cc43a24ee Mon Sep 17 00:00:00 2001 From: Donatas Abraitis Date: Sun, 29 Oct 2023 22:44:45 +0200 Subject: [PATCH] bgpd: Ignore handling NLRIs if we received MP_UNREACH_NLRI If we receive MP_UNREACH_NLRI, we should stop handling remaining NLRIs if no mandatory path attributes received. In other words, if MP_UNREACH_NLRI received, the remaining NLRIs should be handled as a new data, but without mandatory attributes, it's a malformed packet. In normal case, this MUST not happen at all, but to avoid crashing bgpd, we MUST handle that. Reported-by: Iggy Frankovic Signed-off-by: Donatas Abraitis Signed-off-by: Christian Breunig (cherry picked from commit c37119df45bbf4ef713bc10475af2ee06e12f3bf) --- bgpd/bgp_attr.c | 19 ++++++++++--------- bgpd/bgp_attr.h | 1 + bgpd/bgp_packet.c | 7 ++++++- 3 files changed, 17 insertions(+), 10 deletions(-) diff --git a/bgpd/bgp_attr.c b/bgpd/bgp_attr.c index 4bc28fe237..c51e5acb50 100644 --- a/bgpd/bgp_attr.c +++ b/bgpd/bgp_attr.c @@ -2850,15 +2850,6 @@ static int bgp_attr_check(struct peer *peer, struct attr *attr) if (CHECK_FLAG(peer->cap, PEER_CAP_RESTART_RCV) && !attr->flag) return BGP_ATTR_PARSE_PROCEED; - /* "An UPDATE message that contains the MP_UNREACH_NLRI is not required - to carry any other path attributes.", though if MP_REACH_NLRI or NLRI - are present, it should. Check for any other attribute being present - instead. - */ - if ((!CHECK_FLAG(attr->flag, ATTR_FLAG_BIT(BGP_ATTR_MP_REACH_NLRI)) && - CHECK_FLAG(attr->flag, ATTR_FLAG_BIT(BGP_ATTR_MP_UNREACH_NLRI)))) - return BGP_ATTR_PARSE_PROCEED; - if (!CHECK_FLAG(attr->flag, ATTR_FLAG_BIT(BGP_ATTR_ORIGIN))) type = BGP_ATTR_ORIGIN; @@ -2877,6 +2868,16 @@ static int bgp_attr_check(struct peer *peer, struct attr *attr) && !CHECK_FLAG(attr->flag, ATTR_FLAG_BIT(BGP_ATTR_LOCAL_PREF))) type = BGP_ATTR_LOCAL_PREF; + /* An UPDATE message that contains the MP_UNREACH_NLRI is not required + * to carry any other path attributes. Though if MP_REACH_NLRI or NLRI + * are present, it should. Check for any other attribute being present + * instead. + */ + if (!CHECK_FLAG(attr->flag, ATTR_FLAG_BIT(BGP_ATTR_MP_REACH_NLRI)) && + CHECK_FLAG(attr->flag, ATTR_FLAG_BIT(BGP_ATTR_MP_UNREACH_NLRI))) + return type ? BGP_ATTR_PARSE_MISSING_MANDATORY + : BGP_ATTR_PARSE_PROCEED; + /* If any of the well-known mandatory attributes are not present * in an UPDATE message, then "treat-as-withdraw" MUST be used. */ diff --git a/bgpd/bgp_attr.h b/bgpd/bgp_attr.h index e6e953364b..cf9c681b0d 100644 --- a/bgpd/bgp_attr.h +++ b/bgpd/bgp_attr.h @@ -339,6 +339,7 @@ typedef enum { */ BGP_ATTR_PARSE_ERROR_NOTIFYPLS = -3, BGP_ATTR_PARSE_EOR = -4, + BGP_ATTR_PARSE_MISSING_MANDATORY = -5, } bgp_attr_parse_ret_t; struct bpacket_attr_vec_arr; diff --git a/bgpd/bgp_packet.c b/bgpd/bgp_packet.c index 2c8a375a55..164e7ae721 100644 --- a/bgpd/bgp_packet.c +++ b/bgpd/bgp_packet.c @@ -1625,7 +1625,12 @@ static int bgp_update_receive(struct peer *peer, bgp_size_t size) /* Network Layer Reachability Information. */ update_len = end - stream_pnt(s); - if (update_len) { + /* If we received MP_UNREACH_NLRI attribute, but also NLRIs, then + * NLRIs should be handled as a new data. Though, if we received + * NLRIs without mandatory attributes, they should be ignored. + */ + if (update_len && attribute_len && + attr_parse_ret != BGP_ATTR_PARSE_MISSING_MANDATORY) { /* Set NLRI portion to structure. */ nlris[NLRI_UPDATE].afi = AFI_IP; nlris[NLRI_UPDATE].safi = SAFI_UNICAST; -- 2.39.5