netdev - [PATCH ipsec] xfrm: interface: fix ipv4 pmtu check to honor ip header df

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>] [day] [month] [year] [list]

Message-Id: <20210219172127.2223831-1-eyal.birger@gmail.com>
Date:   Fri, 19 Feb 2021 19:21:27 +0200
From:   Eyal Birger <eyal.birger@...il.com>
To:     steffen.klassert@...unet.com, herbert@...dor.apana.org.au,
        davem@...emloft.net, kuba@...nel.org
Cc:     netdev@...r.kernel.org, sd@...asysnail.net,
        Eyal Birger <eyal.birger@...il.com>
Subject: [PATCH ipsec] xfrm: interface: fix ipv4 pmtu check to honor ip header df

Frag needed should only be sent if the header enables DF.

This fix allows packets larger than MTU to pass the xfrm interface
and be fragmented after encapsulation, aligning behavior with
non-interface xfrm.

Fixes: f203b76d7809 ("xfrm: Add virtual xfrm interfaces")
Signed-off-by: Eyal Birger <eyal.birger@...il.com>
---
 net/xfrm/xfrm_interface.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/net/xfrm/xfrm_interface.c b/net/xfrm/xfrm_interface.c
index 697cdcfbb5e1..257b3c8b3995 100644
--- a/net/xfrm/xfrm_interface.c
+++ b/net/xfrm/xfrm_interface.c
@@ -304,13 +304,16 @@ xfrmi_xmit2(struct sk_buff *skb, struct net_device *dev, struct flowi *fl)
 				mtu = IPV6_MIN_MTU;
 
 			icmpv6_ndo_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
-		} else {
+			err = -EMSGSIZE;
+			goto tx_err_dst_release;
+		}
+
+		if (ip_hdr(skb)->frag_off & htons(IP_DF)) {
 			icmp_ndo_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
 				      htonl(mtu));
+			err = -EMSGSIZE;
+			goto tx_err_dst_release;
 		}
-
-		dst_release(dst);
-		return -EMSGSIZE;
 	}
 
 	xfrmi_scrub_packet(skb, !net_eq(xi->net, dev_net(dev)));
-- 
2.25.1