[PATCH 11/16] netfilter: nfnetlink_cttimeout: fetch timeouts for udplite and gre, too

[Pablo Neira Ayuso]

From: Florian Westphal <f...@strlen.de>

syzbot was able to trigger the WARN in cttimeout_default_get() by
passing UDPLITE as l4protocol.  Alias UDPLITE to UDP, both use
same timeout values.

Furthermore, also fetch GRE timeouts.  GRE is a bit more complicated,
as it still can be a module and its netns_proto_gre struct layout isn't
visible outside of the gre module. Can't move timeouts around, it
appears conntrack sysctl unregister assumes net_generic() returns
nf_proto_net, so we get crash. Expose layout of netns_proto_gre instead.

A followup nf-next patch could make gre tracker be built-in as well
if needed, its not that large.

Last, make the WARN() mention the missing protocol value in case
anything else is missing.

Reported-by: syzbot+2fae8fa157dd92618...@syzkaller.appspotmail.com
Fixes: 8866df9264a3 ("netfilter: nfnetlink_cttimeout: pass default timeout 
policy to obj_to_nlattr")
Signed-off-by: Florian Westphal <f...@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pa...@netfilter.org>
---
 include/linux/netfilter/nf_conntrack_proto_gre.h | 13 +++++++++++++
 net/netfilter/nf_conntrack_proto_gre.c           | 14 ++------------
 net/netfilter/nfnetlink_cttimeout.c              | 15 +++++++++++++--
 3 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/include/linux/netfilter/nf_conntrack_proto_gre.h 
b/include/linux/netfilter/nf_conntrack_proto_gre.h
index b8d95564bd53..14edb795ab43 100644
--- a/include/linux/netfilter/nf_conntrack_proto_gre.h
+++ b/include/linux/netfilter/nf_conntrack_proto_gre.h
@@ -21,6 +21,19 @@ struct nf_ct_gre_keymap {
        struct nf_conntrack_tuple tuple;
 };
 
+enum grep_conntrack {
+       GRE_CT_UNREPLIED,
+       GRE_CT_REPLIED,
+       GRE_CT_MAX
+};
+
+struct netns_proto_gre {
+       struct nf_proto_net     nf;
+       rwlock_t                keymap_lock;
+       struct list_head        keymap_list;
+       unsigned int            gre_timeouts[GRE_CT_MAX];
+};
+
 /* add new tuple->key_reply pair to keymap */
 int nf_ct_gre_keymap_add(struct nf_conn *ct, enum ip_conntrack_dir dir,
                         struct nf_conntrack_tuple *t);
diff --git a/net/netfilter/nf_conntrack_proto_gre.c 
b/net/netfilter/nf_conntrack_proto_gre.c
index 9b48dc8b4b88..2a5e56c6d8d9 100644
--- a/net/netfilter/nf_conntrack_proto_gre.c
+++ b/net/netfilter/nf_conntrack_proto_gre.c
@@ -43,24 +43,12 @@
 #include <linux/netfilter/nf_conntrack_proto_gre.h>
 #include <linux/netfilter/nf_conntrack_pptp.h>
 
-enum grep_conntrack {
-       GRE_CT_UNREPLIED,
-       GRE_CT_REPLIED,
-       GRE_CT_MAX
-};
-
 static const unsigned int gre_timeouts[GRE_CT_MAX] = {
        [GRE_CT_UNREPLIED]      = 30*HZ,
        [GRE_CT_REPLIED]        = 180*HZ,
 };
 
 static unsigned int proto_gre_net_id __read_mostly;
-struct netns_proto_gre {
-       struct nf_proto_net     nf;
-       rwlock_t                keymap_lock;
-       struct list_head        keymap_list;
-       unsigned int            gre_timeouts[GRE_CT_MAX];
-};
 
 static inline struct netns_proto_gre *gre_pernet(struct net *net)
 {
@@ -402,6 +390,8 @@ static int __init nf_ct_proto_gre_init(void)
 {
        int ret;
 
+       BUILD_BUG_ON(offsetof(struct netns_proto_gre, nf) != 0);
+
        ret = register_pernet_subsys(&proto_gre_net_ops);
        if (ret < 0)
                goto out_pernet;
diff --git a/net/netfilter/nfnetlink_cttimeout.c 
b/net/netfilter/nfnetlink_cttimeout.c
index a518eb162344..109b0d27345a 100644
--- a/net/netfilter/nfnetlink_cttimeout.c
+++ b/net/netfilter/nfnetlink_cttimeout.c
@@ -455,7 +455,8 @@ static int cttimeout_default_get(struct net *net, struct 
sock *ctnl,
        case IPPROTO_TCP:
                timeouts = nf_tcp_pernet(net)->timeouts;
                break;
-       case IPPROTO_UDP:
+       case IPPROTO_UDP: /* fallthrough */
+       case IPPROTO_UDPLITE:
                timeouts = nf_udp_pernet(net)->timeouts;
                break;
        case IPPROTO_DCCP:
@@ -471,11 +472,21 @@ static int cttimeout_default_get(struct net *net, struct 
sock *ctnl,
                timeouts = nf_sctp_pernet(net)->timeouts;
 #endif
                break;
+       case IPPROTO_GRE:
+#ifdef CONFIG_NF_CT_PROTO_GRE
+               if (l4proto->net_id) {
+                       struct netns_proto_gre *net_gre;
+
+                       net_gre = net_generic(net, *l4proto->net_id);
+                       timeouts = net_gre->gre_timeouts;
+               }
+#endif
+               break;
        case 255:
                timeouts = &nf_generic_pernet(net)->timeout;
                break;
        default:
-               WARN_ON_ONCE(1);
+               WARN_ONCE(1, "Missing timeouts for proto %d", l4proto->l4proto);
                break;
        }
 
-- 
2.11.0