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Subject[PATCH 4.19 043/101] netfilter: nfnetlink_cttimeout: fetch timeouts for udplite and gre, too
Date
commit 89259088c1b7fecb43e8e245dc931909132a4e03 upstream

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+2fae8fa157dd92618cae@syzkaller.appspotmail.com
Fixes: 8866df9264a3 ("netfilter: nfnetlink_cttimeout: pass default timeout policy to obj_to_nlattr")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Zubin Mithra <zsm@chromium.org>
Signed-off-by: Sasha Levin (Microsoft) <sashal@kernel.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 650eb4fba2c5..841c472aae1c 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)
{
@@ -408,6 +396,8 @@ 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 1dc4ea327cbe..70a7382b9787 100644
--- a/net/netfilter/nfnetlink_cttimeout.c
+++ b/net/netfilter/nfnetlink_cttimeout.c
@@ -469,7 +469,8 @@ static int cttimeout_default_get(struct net *net, struct sock *ctnl,
case IPPROTO_TCP:
timeouts = net->ct.nf_ct_proto.tcp.timeouts;
break;
- case IPPROTO_UDP:
+ case IPPROTO_UDP: /* fallthrough */
+ case IPPROTO_UDPLITE:
timeouts = net->ct.nf_ct_proto.udp.timeouts;
break;
case IPPROTO_DCCP:
@@ -483,13 +484,23 @@ static int cttimeout_default_get(struct net *net, struct sock *ctnl,
case IPPROTO_SCTP:
#ifdef CONFIG_NF_CT_PROTO_SCTP
timeouts = net->ct.nf_ct_proto.sctp.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 = &net->ct.nf_ct_proto.generic.timeout;
break;
default:
- WARN_ON_ONCE(1);
+ WARN_ONCE(1, "Missing timeouts for proto %d", l4proto->l4proto);
break;
}

--
2.19.1


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