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Date: Wed, 20 Sep 2017 18:54:02 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: netdev@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>,
Pablo Neira Ayuso <pablo@...filter.org>,
Florian Westphal <fw@...len.de>,
Eric Dumazet <edumazet@...gle.com>,
Hannes Frederic Sowa <hannes@...essinduktion.org>
Subject: [PATCH net-next 2/5] net: allow early demux to fetch noref socket
We must be careful to avoid leaking such sockets outside
the RCU section containing the early demux call; we clear
them on nonlocal delivery.
For ipv4 we must take care of local mcast delivery, too,
since udp early demux works also for mcast addresses.
Also update all iptables/nftables extension that can
happen in the input chain and can transmit the skb outside
such patch, namely TEE, nft_dup and nfqueue.
Signed-off-by: Paolo Abeni <pabeni@...hat.com>
---
net/ipv4/ip_input.c | 12 ++++++++++++
net/ipv4/ipmr.c | 18 ++++++++++++++----
net/ipv4/netfilter/nf_dup_ipv4.c | 3 +++
net/ipv6/ip6_input.c | 7 ++++++-
net/ipv6/netfilter/nf_dup_ipv6.c | 3 +++
net/netfilter/nf_queue.c | 3 +++
6 files changed, 41 insertions(+), 5 deletions(-)
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index fa2dc8f692c6..e71abc8b698c 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -349,6 +349,18 @@ static int ip_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
__NET_INC_STATS(net, LINUX_MIB_IPRPFILTER);
goto drop;
}
+
+ /* Since the sk has no reference to the socket, we must
+ * clear it before escaping this RCU section.
+ * The sk is just an hint and we know we are not going to use
+ * it outside the input path.
+ */
+ if (skb_dst(skb)->input != ip_local_deliver
+#ifdef CONFIG_IP_MROUTE
+ && skb_dst(skb)->input != ip_mr_input
+#endif
+ )
+ skb_clear_noref_sk(skb);
}
#ifdef CONFIG_IP_ROUTE_CLASSID
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index c9b3e6e069ae..76642af79038 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -1978,11 +1978,12 @@ static struct mr_table *ipmr_rt_fib_lookup(struct net *net, struct sk_buff *skb)
*/
int ip_mr_input(struct sk_buff *skb)
{
- struct mfc_cache *cache;
- struct net *net = dev_net(skb->dev);
int local = skb_rtable(skb)->rt_flags & RTCF_LOCAL;
- struct mr_table *mrt;
+ struct net *net = dev_net(skb->dev);
+ struct mfc_cache *cache;
struct net_device *dev;
+ struct mr_table *mrt;
+ struct sock *sk;
/* skb->dev passed in is the loX master dev for vrfs.
* As there are no vifs associated with loopback devices,
@@ -2052,6 +2053,9 @@ int ip_mr_input(struct sk_buff *skb)
skb = skb2;
}
+ /* avoid leaking the noref sk on forward path */
+ skb_clear_noref_sk(skb);
+
read_lock(&mrt_lock);
vif = ipmr_find_vif(mrt, dev);
if (vif >= 0) {
@@ -2065,12 +2069,18 @@ int ip_mr_input(struct sk_buff *skb)
return -ENODEV;
}
+ /* avoid leaking the noref sk on forward path... */
+ sk = skb_clear_noref_sk(skb);
read_lock(&mrt_lock);
ip_mr_forward(net, mrt, dev, skb, cache, local);
read_unlock(&mrt_lock);
- if (local)
+ if (local) {
+ /* ... but preserve it for local delivery */
+ if (sk)
+ skb_set_noref_sk(skb, sk);
return ip_local_deliver(skb);
+ }
return 0;
diff --git a/net/ipv4/netfilter/nf_dup_ipv4.c b/net/ipv4/netfilter/nf_dup_ipv4.c
index 39895b9ddeb9..bf8b78492fc8 100644
--- a/net/ipv4/netfilter/nf_dup_ipv4.c
+++ b/net/ipv4/netfilter/nf_dup_ipv4.c
@@ -71,6 +71,9 @@ void nf_dup_ipv4(struct net *net, struct sk_buff *skb, unsigned int hooknum,
nf_reset(skb);
nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
#endif
+ /* Avoid leaking noref sk outside the input path */
+ skb_clear_noref_sk(skb);
+
/*
* If we are in PREROUTING/INPUT, decrease the TTL to mitigate potential
* loops between two hosts.
diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index 9ee208a348f5..9aa6baffd4b9 100644
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -65,9 +65,14 @@ int ip6_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
if (ipprot && (edemux = READ_ONCE(ipprot->early_demux)))
edemux(skb);
}
- if (!skb_valid_dst(skb))
+ if (!skb_valid_dst(skb)) {
ip6_route_input(skb);
+ /* see comment on ipv4 edmux */
+ if (skb_dst(skb)->input != ip6_input)
+ skb_clear_noref_sk(skb);
+ }
+
return dst_input(skb);
}
diff --git a/net/ipv6/netfilter/nf_dup_ipv6.c b/net/ipv6/netfilter/nf_dup_ipv6.c
index 4a7ddeddbaab..939f6a2238f9 100644
--- a/net/ipv6/netfilter/nf_dup_ipv6.c
+++ b/net/ipv6/netfilter/nf_dup_ipv6.c
@@ -60,6 +60,9 @@ void nf_dup_ipv6(struct net *net, struct sk_buff *skb, unsigned int hooknum,
nf_reset(skb);
nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
#endif
+ /* Avoid leaking noref sk outside the input path */
+ skb_clear_noref_sk(skb);
+
if (hooknum == NF_INET_PRE_ROUTING ||
hooknum == NF_INET_LOCAL_IN) {
struct ipv6hdr *iph = ipv6_hdr(skb);
diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c
index f7e21953b1de..100eff08cb51 100644
--- a/net/netfilter/nf_queue.c
+++ b/net/netfilter/nf_queue.c
@@ -145,6 +145,9 @@ static int __nf_queue(struct sk_buff *skb, const struct nf_hook_state *state,
.size = sizeof(*entry) + afinfo->route_key_size,
};
+ /* Avoid leaking noref sk outside the input path */
+ skb_clear_noref_sk(skb);
+
nf_queue_entry_get_refs(entry);
skb_dst_force(skb);
afinfo->saveroute(skb, entry);
--
2.13.5
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