Commit message: sock_diag: Fix out-of-bounds access to sock_diag_handlers[]

Userland can send a netlink message requesting SOCK_DIAG_BY_FAMILY
with a family greater or equal then AF_MAX -- the array size of
sock_diag_handlers[]. The current code does not test for this
condition therefore is vulnerable to an out-of-bound access opening
doors for a privilege escalation.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
CVE: CVE-2013-1763
CWE: CWE-20
Vulnerability description: Array index error in the __sock_diag_rcv_msg function in net/core/sock_diag.c in the Linux kernel before 3.7.10 allows local users to gain privileges via a large family value in a Netlink message.

Project: linux
File: sock_diag.c

static void __net_exit diag_net_exit(struct net *net)
{
	netlink_kernel_release(net->diag_nlsk);
	net->diag_nlsk = NULL;
}

Project: linux
File: sock_diag.c

static int __net_init diag_net_init(struct net *net)
{
	struct netlink_kernel_cfg cfg = {
		.input	= sock_diag_rcv,
	};

	net->diag_nlsk = netlink_kernel_create(net, NETLINK_SOCK_DIAG, &cfg);
	return net->diag_nlsk == NULL ? -ENOMEM : 0;
}

Project: linux
File: sock_diag.c

static void __exit sock_diag_exit(void)
{
	unregister_pernet_subsys(&diag_net_ops);
}

Project: linux
File: sock_diag.c

static int __init sock_diag_init(void)
{
	return register_pernet_subsys(&diag_net_ops);
}

Project: linux
File: sock_diag.c

static const inline struct sock_diag_handler *sock_diag_lock_handler(int family)
{
	if (sock_diag_handlers[family] == NULL)
		request_module("net-pf-%d-proto-%d-type-%d", PF_NETLINK,
				NETLINK_SOCK_DIAG, family);

	mutex_lock(&sock_diag_table_mutex);
	return sock_diag_handlers[family];
}

Project: linux
File: sock_diag.c

int sock_diag_put_meminfo(struct sock *sk, struct sk_buff *skb, int attrtype)
{
	u32 mem[SK_MEMINFO_VARS];

	mem[SK_MEMINFO_RMEM_ALLOC] = sk_rmem_alloc_get(sk);
	mem[SK_MEMINFO_RCVBUF] = sk->sk_rcvbuf;
	mem[SK_MEMINFO_WMEM_ALLOC] = sk_wmem_alloc_get(sk);
	mem[SK_MEMINFO_SNDBUF] = sk->sk_sndbuf;
	mem[SK_MEMINFO_FWD_ALLOC] = sk->sk_forward_alloc;
	mem[SK_MEMINFO_WMEM_QUEUED] = sk->sk_wmem_queued;
	mem[SK_MEMINFO_OPTMEM] = atomic_read(&sk->sk_omem_alloc);
	mem[SK_MEMINFO_BACKLOG] = sk->sk_backlog.len;

	return nla_put(skb, attrtype, sizeof(mem), &mem);
}

Project: linux
File: sock_diag.c

static void sock_diag_rcv(struct sk_buff *skb)
{
	mutex_lock(&sock_diag_mutex);
	netlink_rcv_skb(skb, &sock_diag_rcv_msg);
	mutex_unlock(&sock_diag_mutex);
}

Project: linux
File: sock_diag.c

static int sock_diag_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
{
	int ret;

	switch (nlh->nlmsg_type) {
	case TCPDIAG_GETSOCK:
	case DCCPDIAG_GETSOCK:
		if (inet_rcv_compat == NULL)
			request_module("net-pf-%d-proto-%d-type-%d", PF_NETLINK,
					NETLINK_SOCK_DIAG, AF_INET);

		mutex_lock(&sock_diag_table_mutex);
		if (inet_rcv_compat != NULL)
			ret = inet_rcv_compat(skb, nlh);
		else
			ret = -EOPNOTSUPP;
		mutex_unlock(&sock_diag_table_mutex);

		return ret;
	case SOCK_DIAG_BY_FAMILY:
		return __sock_diag_rcv_msg(skb, nlh);
	default:
		return -EINVAL;
	}
}

Project: linux
File: sock_diag.c

int sock_diag_register(const struct sock_diag_handler *hndl)
{
	int err = 0;

	if (hndl->family >= AF_MAX)
		return -EINVAL;

	mutex_lock(&sock_diag_table_mutex);
	if (sock_diag_handlers[hndl->family])
		err = -EBUSY;
	else
		sock_diag_handlers[hndl->family] = hndl;
	mutex_unlock(&sock_diag_table_mutex);

	return err;
}

Project: linux
File: sock_diag.c

void sock_diag_register_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh))
{
	mutex_lock(&sock_diag_table_mutex);
	inet_rcv_compat = fn;
	mutex_unlock(&sock_diag_table_mutex);
}

Project: linux
File: sock_diag.c

void sock_diag_save_cookie(void *sk, __u32 *cookie)
{
	cookie[0] = (u32)(unsigned long)sk;
	cookie[1] = (u32)(((unsigned long)sk >> 31) >> 1);
}

Project: linux
File: sock_diag.c

void sock_diag_unregister(const struct sock_diag_handler *hnld)
{
	int family = hnld->family;

	if (family >= AF_MAX)
		return;

	mutex_lock(&sock_diag_table_mutex);
	BUG_ON(sock_diag_handlers[family] != hnld);
	sock_diag_handlers[family] = NULL;
	mutex_unlock(&sock_diag_table_mutex);
}

Project: linux
File: sock_diag.c

void sock_diag_unregister_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh))
{
	mutex_lock(&sock_diag_table_mutex);
	inet_rcv_compat = NULL;
	mutex_unlock(&sock_diag_table_mutex);
}