[42/65] ipv6: do not clear pinet6 field

Steven Rostedt
2013-06-03T22:16:23Z

[-- Attachment #1: 0042-ipv6-do-not-clear-pinet6-field.patch --]
[-- Type: text/plain, Size: 5649 bytes --]

3.6.11.5 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit f77d602124d865c38705df7fa25c03de9c284ad2 ]

We have seen multiple NULL dereferences in __inet6_lookup_established()

After analysis, I found that inet6_sk() could be NULL while the
check for sk_family == AF_INET6 was true.

Bug was added in linux-2.6.29 when RCU lookups were introduced in UDP
and TCP stacks.

Once an IPv6 socket, using SLAB_DESTROY_BY_RCU is inserted in a hash
table, we no longer can clear pinet6 field.

This patch extends logic used in commit fcbdf09d9652c891
("net: fix nulls list corruptions in sk_prot_alloc")

TCP/UDP/UDPLite IPv6 protocols provide their own .clear_sk() method
to make sure we do not clear pinet6 field.

At socket clone phase, we do not really care, as cloning the parent (non
NULL) pinet6 is not adding a fatal race.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
include/net/sock.h | 12 ++++++++++++
net/core/sock.c | 12 ------------
net/ipv6/tcp_ipv6.c | 12 ++++++++++++
net/ipv6/udp.c | 13 ++++++++++++-
net/ipv6/udp_impl.h | 2 ++
net/ipv6/udplite.c | 2 +-
6 files changed, 39 insertions(+), 14 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 450a2af..30662c9 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -837,6 +837,18 @@ struct inet_hashinfo;
struct raw_hashinfo;
struct module;

+/*
+ * caches using SLAB_DESTROY_BY_RCU should let .next pointer from nulls nodes
+ * un-modified. Special care is taken when initializing object to zero.
+ */
+static inline void sk_prot_clear_nulls(struct sock *sk, int size)
+{
+ if (offsetof(struct sock, sk_node.next) != 0)
+ memset(sk, 0, offsetof(struct sock, sk_node.next));
+ memset(&sk->sk_node.pprev, 0,
+ size - offsetof(struct sock, sk_node.pprev));
+}
+
/* Networking protocol blocks we attach to sockets.
* socket layer -> transport layer interface
* transport -> network interface is defined by struct inet_proto
diff --git a/net/core/sock.c b/net/core/sock.c
index e794a4a..be63d03 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1140,18 +1140,6 @@ static void sock_copy(struct sock *nsk, const struct sock *osk)
#endif
}

-/*
- * caches using SLAB_DESTROY_BY_RCU should let .next pointer from nulls nodes
- * un-modified. Special care is taken when initializing object to zero.
- */
-static inline void sk_prot_clear_nulls(struct sock *sk, int size)
-{
- if (offsetof(struct sock, sk_node.next) != 0)
- memset(sk, 0, offsetof(struct sock, sk_node.next));
- memset(&sk->sk_node.pprev, 0,
- size - offsetof(struct sock, sk_node.pprev));
-}
-
void sk_prot_clear_portaddr_nulls(struct sock *sk, int size)
{
unsigned long nulls1, nulls2;
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index e3eec75..e5ec801 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -2013,6 +2013,17 @@ void tcp6_proc_exit(struct net *net)
}
#endif

+static void tcp_v6_clear_sk(struct sock *sk, int size)
+{
+ struct inet_sock *inet = inet_sk(sk);
+
+ /* we do not want to clear pinet6 field, because of RCU lookups */
+ sk_prot_clear_nulls(sk, offsetof(struct inet_sock, pinet6));
+
+ size -= offsetof(struct inet_sock, pinet6) + sizeof(inet->pinet6);
+ memset(&inet->pinet6 + 1, 0, size);
+}
+
struct proto tcpv6_prot = {
.name = "TCPv6",
.owner = THIS_MODULE,
@@ -2056,6 +2067,7 @@ struct proto tcpv6_prot = {
#ifdef CONFIG_MEMCG_KMEM
.proto_cgroup = tcp_proto_cgroup,
#endif
+ .clear_sk = tcp_v6_clear_sk,
};

static const struct inet6_protocol tcpv6_protocol = {
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 07e2bfe..08a1878 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1517,6 +1517,17 @@ void udp6_proc_exit(struct net *net) {
}
#endif /* CONFIG_PROC_FS */

+void udp_v6_clear_sk(struct sock *sk, int size)
+{
+ struct inet_sock *inet = inet_sk(sk);
+
+ /* we do not want to clear pinet6 field, because of RCU lookups */
+ sk_prot_clear_portaddr_nulls(sk, offsetof(struct inet_sock, pinet6));
+
+ size -= offsetof(struct inet_sock, pinet6) + sizeof(inet->pinet6);
+ memset(&inet->pinet6 + 1, 0, size);
+}
+
/* ------------------------------------------------------------------------ */

struct proto udpv6_prot = {
@@ -1547,7 +1558,7 @@ struct proto udpv6_prot = {
.compat_setsockopt = compat_udpv6_setsockopt,
.compat_getsockopt = compat_udpv6_getsockopt,
#endif
- .clear_sk = sk_prot_clear_portaddr_nulls,
+ .clear_sk = udp_v6_clear_sk,
};

static struct inet_protosw udpv6_protosw = {
diff --git a/net/ipv6/udp_impl.h b/net/ipv6/udp_impl.h
index d757104..4691ed5 100644
--- a/net/ipv6/udp_impl.h
+++ b/net/ipv6/udp_impl.h
@@ -31,6 +31,8 @@ extern int udpv6_recvmsg(struct kiocb *iocb, struct sock *sk,
extern int udpv6_queue_rcv_skb(struct sock * sk, struct sk_buff *skb);
extern void udpv6_destroy_sock(struct sock *sk);

+extern void udp_v6_clear_sk(struct sock *sk, int size);
+
#ifdef CONFIG_PROC_FS
extern int udp6_seq_show(struct seq_file *seq, void *v);
#endif
diff --git a/net/ipv6/udplite.c b/net/ipv6/udplite.c
index 1d08e21..dfcc4be 100644
--- a/net/ipv6/udplite.c
+++ b/net/ipv6/udplite.c
@@ -56,7 +56,7 @@ struct proto udplitev6_prot = {
.compat_setsockopt = compat_udpv6_setsockopt,
.compat_getsockopt = compat_udpv6_getsockopt,
#endif
- .clear_sk = sk_prot_clear_portaddr_nulls,
+ .clear_sk = udp_v6_clear_sk,
};

static struct inet_protosw udplite6_protosw = {
--
1.7.10.4