lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Fri, 31 Jul 2020 09:18:03 +0200
From:   Steffen Klassert <steffen.klassert@...unet.com>
To:     David Miller <davem@...emloft.net>
CC:     Herbert Xu <herbert@...dor.apana.org.au>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        <netdev@...r.kernel.org>
Subject: [PATCH 09/10] espintcp: handle short messages instead of breaking the encap socket

From: Sabrina Dubroca <sd@...asysnail.net>

Currently, short messages (less than 4 bytes after the length header)
will break the stream of messages. This is unnecessary, since we can
still parse messages even if they're too short to contain any usable
data. This is also bogus, as keepalive messages (a single 0xff byte),
though not needed with TCP encapsulation, should be allowed.

This patch changes the stream parser so that short messages are
accepted and dropped in the kernel. Messages that contain a valid SPI
or non-ESP header are processed as before.

Fixes: e27cca96cd68 ("xfrm: add espintcp (RFC 8229)")
Reported-by: Andrew Cagney <cagney@...reswan.org>
Signed-off-by: Sabrina Dubroca <sd@...asysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com>
---
 net/xfrm/espintcp.c | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/net/xfrm/espintcp.c b/net/xfrm/espintcp.c
index cb83e3664680..0a91b07f2b43 100644
--- a/net/xfrm/espintcp.c
+++ b/net/xfrm/espintcp.c
@@ -49,9 +49,32 @@ static void espintcp_rcv(struct strparser *strp, struct sk_buff *skb)
 	struct espintcp_ctx *ctx = container_of(strp, struct espintcp_ctx,
 						strp);
 	struct strp_msg *rxm = strp_msg(skb);
+	int len = rxm->full_len - 2;
 	u32 nonesp_marker;
 	int err;
 
+	/* keepalive packet? */
+	if (unlikely(len == 1)) {
+		u8 data;
+
+		err = skb_copy_bits(skb, rxm->offset + 2, &data, 1);
+		if (err < 0) {
+			kfree_skb(skb);
+			return;
+		}
+
+		if (data == 0xff) {
+			kfree_skb(skb);
+			return;
+		}
+	}
+
+	/* drop other short messages */
+	if (unlikely(len <= sizeof(nonesp_marker))) {
+		kfree_skb(skb);
+		return;
+	}
+
 	err = skb_copy_bits(skb, rxm->offset + 2, &nonesp_marker,
 			    sizeof(nonesp_marker));
 	if (err < 0) {
@@ -91,7 +114,7 @@ static int espintcp_parse(struct strparser *strp, struct sk_buff *skb)
 		return err;
 
 	len = be16_to_cpu(blen);
-	if (len < 6)
+	if (len < 2)
 		return -EINVAL;
 
 	return len;
-- 
2.17.1

Powered by blists - more mailing lists