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ipv6: do not clear pinet6 field

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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 fcbdf09d96
("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>
This commit is contained in:
Eric Dumazet 2013-05-09 10:28:16 +00:00 committed by David S. Miller
parent 233c7df082
commit f77d602124
6 changed files with 39 additions and 14 deletions
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12
include/net/sock.h
View file

@ -866,6 +866,18 @@ 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

12
net/core/sock.c
View file

@ -1217,18 +1217,6 @@ 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;

12
net/ipv6/tcp_ipv6.c
View file

@ -1890,6 +1890,17 @@ 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,
@ -1933,6 +1944,7 @@ 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 = {

13
net/ipv6/udp.c
View file

@ -1432,6 +1432,17 @@ 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 = {
@ -1462,7 +1473,7 @@ 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 = {

2
net/ipv6/udp_impl.h
View file

@ -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

2
net/ipv6/udplite.c
View file

@ -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 = {