File _service:tar_scm_kernel_repo:backport-iptunnel-... of Package iproute

File _service:tar_scm_kernel_repo:backport-iptunnel-detect-protocol-mismatch-on-tunnel-change.patch of Package iproute

From 8cc2eac60d5f1f5ec2c40d02c0003731c8b610dc Mon Sep 17 00:00:00 2001
From: Stephen Hemminger <stephen@networkplumber.org>
Date: Mon, 10 Apr 2023 16:22:51 -0700
Subject: [PATCH] iptunnel: detect protocol mismatch on tunnel change

If attempt is made to change an IPv6 tunnel by using IPv4
parameters, a stack overflow would happen and garbage request
would be passed to kernel.

Example:
ip tunnel add gre1 mode ip6gre local 2001:db8::1 remote 2001:db8::2 ttl 255
ip tunnel change gre1 mode gre local 192.168.0.0 remote 192.168.0.1 ttl 255

The second command should fail because it attempting set IPv4 addresses
on a GRE tunnel that is IPv6.

Do best effort detection of this mismatch by giving a bigger buffer to get
tunnel request, and checking that the IP header is IPv4. It is still possible
but unlikely that byte would match in IPv6 tunnel paramater, but good enough
to catch the obvious cases.

Bug-Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1032642
Tested-by: Luca Boccassi <bluca@debian.org>
Reported-by: Robin <imer@imer.cc>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 ip/iptunnel.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/ip/iptunnel.c b/ip/iptunnel.c
index 02c3670b..b6da1459 100644
--- a/ip/iptunnel.c
+++ b/ip/iptunnel.c
@@ -17,6 +17,7 @@
 #include <net/if_arp.h>
 #include <linux/ip.h>
 #include <linux/if_tunnel.h>
+#include <linux/ip6_tunnel.h>
 
 #include "rt_names.h"
 #include "utils.h"
@@ -172,11 +173,20 @@ static int parse_args(int argc, char **argv, int cmd, struct ip_tunnel_parm *p)
 			if (get_ifname(p->name, *argv))
 				invarg("\"name\" not a valid ifname", *argv);
 			if (cmd == SIOCCHGTUNNEL && count == 0) {
-				struct ip_tunnel_parm old_p = {};
+				union {
+					struct ip_tunnel_parm ip_tnl;
+					struct ip6_tnl_parm2 ip6_tnl;
+				} old_p = {};
 
 				if (tnl_get_ioctl(*argv, &old_p))
 					return -1;
-				*p = old_p;
+
+				if (old_p.ip_tnl.iph.version != 4 ||
+				    old_p.ip_tnl.iph.ihl != 5)
+					invarg("\"name\" is not an ip tunnel",
+					       *argv);
+
+				*p = old_p.ip_tnl;
 			}
 		}
 		count++;
-- 
2.27.0