[PATCH 5.4 264/320] xfrm: fix policy lookup for ipv6 gre packets

Greg Kroah-Hartman
2022-01-24T19:50:26Z

From: Ghalem Boudour <ghalem.boudour@6wind.com>

commit bcf141b2eb551b3477b24997ebc09c65f117a803 upstream.

On egress side, xfrm lookup is called from __gre6_xmit() with the
fl6_gre_key field not initialized leading to policies selectors check
failure. Consequently, gre packets are sent without encryption.

On ingress side, INET6_PROTO_NOPOLICY was set, thus packets were not
checked against xfrm policies. Like for egress side, fl6_gre_key should be
correctly set, this is now done in decode_session6().

Fixes: c12b395a4664 ("gre: Support GRE over IPv6")
Cc: stable@vger.kernel.org
Signed-off-by: Ghalem Boudour <ghalem.boudour@6wind.com>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv6/ip6_gre.c | 5 ++++-
net/xfrm/xfrm_policy.c | 21 +++++++++++++++++++++
2 files changed, 25 insertions(+), 1 deletion(-)

--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -743,6 +743,7 @@ static netdev_tx_t __gre6_xmit(struct sk
fl6->daddr = key->u.ipv6.dst;
fl6->flowlabel = key->label;
fl6->flowi6_uid = sock_net_uid(dev_net(dev), NULL);
+ fl6->fl6_gre_key = tunnel_id_to_key32(key->tun_id);

dsfield = key->tos;
flags = key->tun_flags &
@@ -978,6 +979,7 @@ static netdev_tx_t ip6erspan_tunnel_xmit
fl6.daddr = key->u.ipv6.dst;
fl6.flowlabel = key->label;
fl6.flowi6_uid = sock_net_uid(dev_net(dev), NULL);
+ fl6.fl6_gre_key = tunnel_id_to_key32(key->tun_id);

dsfield = key->tos;
if (!(tun_info->key.tun_flags & TUNNEL_ERSPAN_OPT))
@@ -1085,6 +1087,7 @@ static void ip6gre_tnl_link_config_commo
fl6->flowi6_oif = p->link;
fl6->flowlabel = 0;
fl6->flowi6_proto = IPPROTO_GRE;
+ fl6->fl6_gre_key = t->parms.o_key;

if (!(p->flags&IP6_TNL_F_USE_ORIG_TCLASS))
fl6->flowlabel |= IPV6_TCLASS_MASK & p->flowinfo;
@@ -1530,7 +1533,7 @@ static void ip6gre_fb_tunnel_init(struct
static struct inet6_protocol ip6gre_protocol __read_mostly = {
.handler = gre_rcv,
.err_handler = ip6gre_err,
- .flags = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
+ .flags = INET6_PROTO_FINAL,
};

static void ip6gre_destroy_tunnels(struct net *net, struct list_head *head)
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -33,6 +33,7 @@
#include <net/flow.h>
#include <net/xfrm.h>
#include <net/ip.h>
+#include <net/gre.h>
#if IS_ENABLED(CONFIG_IPV6_MIP6)
#include <net/mip6.h>
#endif
@@ -3443,6 +3444,26 @@ decode_session6(struct sk_buff *skb, str
}
fl6->flowi6_proto = nexthdr;
return;
+ case IPPROTO_GRE:
+ if (!onlyproto &&
+ (nh + offset + 12 < skb->data ||
+ pskb_may_pull(skb, nh + offset + 12 - skb->data))) {
+ struct gre_base_hdr *gre_hdr;
+ __be32 *gre_key;
+
+ nh = skb_network_header(skb);
+ gre_hdr = (struct gre_base_hdr *)(nh + offset);
+ gre_key = (__be32 *)(gre_hdr + 1);
+
+ if (gre_hdr->flags & GRE_KEY) {
+ if (gre_hdr->flags & GRE_CSUM)
+ gre_key++;
+ fl6->fl6_gre_key = *gre_key;
+ }
+ }
+ fl6->flowi6_proto = nexthdr;
+ return;
+
#if IS_ENABLED(CONFIG_IPV6_MIP6)
case IPPROTO_MH:
offset += ipv6_optlen(exthdr);