frr/0025-CVE-2023-31490.patch

From 06431bfa7570f169637ebb5898f0b0cc3b010802 Mon Sep 17 00:00:00 2001
From: Donald Sharp <sharpd@nvidia.com>
Date: Tue, 6 Dec 2022 10:23:11 -0500
Subject: [PATCH] bgpd: Ensure stream received has enough data

BGP_PREFIX_SID_SRV6_L3_SERVICE attributes must not
fully trust the length value specified in the nlri.
Always ensure that the amount of data we need to read
can be fullfilled.

Reported-by: Iggy Frankovic <iggyfran@amazon.com>
Signed-off-by: Donald Sharp <sharpd@nvidia.com>
---
 bgpd/bgp_attr.c | 79 ++++++++++++++++---------------------------------
 1 file changed, 25 insertions(+), 54 deletions(-)

diff --git a/bgpd/bgp_attr.c b/bgpd/bgp_attr.c
index c35e45275c9b..5b06bc391375 100644
--- a/bgpd/bgp_attr.c
+++ b/bgpd/bgp_attr.c
@@ -2927,9 +2927,21 @@ bgp_attr_psid_sub(uint8_t type, uint16_t length,
 	uint16_t endpoint_behavior;
 	char buf[BUFSIZ];
 
+	/*
+	 * Check that we actually have at least as much data as
+	 * specified by the length field
+	 */
+	if (STREAM_READABLE(peer->curr) < length) {
+		flog_err(
+			EC_BGP_ATTR_LEN,
+			"Prefix SID specifies length %hu, but only %zu bytes remain",
+			length, STREAM_READABLE(peer->curr));
+		return bgp_attr_malformed(args, BGP_NOTIFY_UPDATE_ATTR_LENG_ERR,
+					  args->total);
+	}
+
 	if (type == BGP_PREFIX_SID_LABEL_INDEX) {
-		if (STREAM_READABLE(peer->curr) < length
-		    || length != BGP_PREFIX_SID_LABEL_INDEX_LENGTH) {
+		if (length != BGP_PREFIX_SID_LABEL_INDEX_LENGTH) {
 			flog_err(EC_BGP_ATTR_LEN,
 				 "Prefix SID label index length is %hu instead of %u",
 				 length, BGP_PREFIX_SID_LABEL_INDEX_LENGTH);
@@ -2951,12 +2963,8 @@ bgp_attr_psid_sub(uint8_t type, uint16_t length,
 		/* Store label index; subsequently, we'll check on
 		 * address-family */
 		attr->label_index = label_index;
-	}
-
-	/* Placeholder code for the IPv6 SID type */
-	else if (type == BGP_PREFIX_SID_IPV6) {
-		if (STREAM_READABLE(peer->curr) < length
-		    || length != BGP_PREFIX_SID_IPV6_LENGTH) {
+	} else if (type == BGP_PREFIX_SID_IPV6) {
+		if (length != BGP_PREFIX_SID_IPV6_LENGTH) {
 			flog_err(EC_BGP_ATTR_LEN,
 				 "Prefix SID IPv6 length is %hu instead of %u",
 				 length, BGP_PREFIX_SID_IPV6_LENGTH);
@@ -2970,10 +2978,7 @@ bgp_attr_psid_sub(uint8_t type, uint16_t length,
 		stream_getw(peer->curr);
 
 		stream_get(&ipv6_sid, peer->curr, 16);
-	}
-
-	/* Placeholder code for the Originator SRGB type */
-	else if (type == BGP_PREFIX_SID_ORIGINATOR_SRGB) {
+	} else if (type == BGP_PREFIX_SID_ORIGINATOR_SRGB) {
 		/*
 		 * ietf-idr-bgp-prefix-sid-05:
 		 *     Length is the total length of the value portion of the
@@ -2998,19 +3003,6 @@ bgp_attr_psid_sub(uint8_t type, uint16_t length,
 				args->total);
 		}
 
-		/*
-		 * Check that we actually have at least as much data as
-		 * specified by the length field
-		 */
-		if (STREAM_READABLE(peer->curr) < length) {
-			flog_err(EC_BGP_ATTR_LEN,
-				 "Prefix SID Originator SRGB specifies length %hu, but only %zu bytes remain",
-				 length, STREAM_READABLE(peer->curr));
-			return bgp_attr_malformed(
-				args, BGP_NOTIFY_UPDATE_ATTR_LENG_ERR,
-				args->total);
-		}
-
 		/*
 		 * Check that the portion of the TLV containing the sequence of
 		 * SRGBs corresponds to a multiple of the SRGB size; to get
@@ -3034,12 +3026,8 @@ bgp_attr_psid_sub(uint8_t type, uint16_t length,
 			stream_get(&srgb_base, peer->curr, 3);
 			stream_get(&srgb_range, peer->curr, 3);
 		}
-	}
-
-	/* Placeholder code for the VPN-SID Service type */
-	else if (type == BGP_PREFIX_SID_VPN_SID) {
-		if (STREAM_READABLE(peer->curr) < length
-		    || length != BGP_PREFIX_SID_VPN_SID_LENGTH) {
+	} else if (type == BGP_PREFIX_SID_VPN_SID) {
+		if (length != BGP_PREFIX_SID_VPN_SID_LENGTH) {
 			flog_err(EC_BGP_ATTR_LEN,
 				 "Prefix SID VPN SID length is %hu instead of %u",
 				 length, BGP_PREFIX_SID_VPN_SID_LENGTH);
@@ -2601,18 +2589,13 @@ static bgp_attr_parse_ret_t bgp_attr_psid_sub(uint8_t type, uint16_t length,
 					 sizeof(struct bgp_attr_srv6_vpn));
 		attr->srv6_vpn->sid_flags = sid_flags;
 		sid_copy(&attr->srv6_vpn->sid, &ipv6_sid);
-	}
-
-	/* Placeholder code for the SRv6 L3 Service type */
-	else if (type == BGP_PREFIX_SID_SRV6_L3_SERVICE) {
-		if (STREAM_READABLE(peer->curr) < length
-		    || length != BGP_PREFIX_SID_SRV6_L3_SERVICE_LENGTH) {
-			flog_err(EC_BGP_ATTR_LEN,
-				 "Prefix SID SRv6 L3-Service length is %hu instead of %u",
-				 length, BGP_PREFIX_SID_SRV6_L3_SERVICE_LENGTH);
-			return bgp_attr_malformed(args,
-				 BGP_NOTIFY_UPDATE_ATTR_LENG_ERR,
-				 args->total);
+		} else if (type == BGP_PREFIX_SID_SRV6_L3_SERVICE) {
+			if (STREAM_READABLE(peer->curr) < 1) {
+				flog_err(EC_BGP_ATTR_LEN,
+				"Prefix SID SRV6 L3 Service not enough data left, it must be at least 1 byte");
+			return bgp_attr_malformed(
+				args, BGP_NOTIFY_UPDATE_ATTR_LENG_ERR,
+				args->total);
 		}
 
 		/* Parse L3-SERVICE Sub-TLV */
@@ -2647,17 +2630,6 @@ static bgp_attr_parse_ret_t bgp_attr_psid_sub(uint8_t type, uint16_t length,
 
 	/* Placeholder code for Unsupported TLV */
 	else {
-
-		if (STREAM_READABLE(peer->curr) < length) {
-			flog_err(
-				EC_BGP_ATTR_LEN,
-				"Prefix SID SRv6 length is %hu - too long, only %zu remaining in this UPDATE",
-				length, STREAM_READABLE(peer->curr));
-			return bgp_attr_malformed(
-				args, BGP_NOTIFY_UPDATE_ATTR_LENG_ERR,
-				args->total);
-		}
-
 		if (bgp_debug_update(peer, NULL, NULL, 1))
 			zlog_debug(
 				"%s attr Prefix-SID sub-type=%u is not supported, skipped",