Commit message: net: guard tcp_set_keepalive() to tcp sockets

Its possible to use RAW sockets to get a crash in
tcp_set_keepalive() / sk_reset_timer()

Fix is to make sure socket is a SOCK_STREAM one.

Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
CVE: CVE-2012-6657
CWE: CWE-264
Vulnerability description: The sock_setsockopt function in net/core/sock.c in the Linux kernel before 3.5.7 does not ensure that a keepalive action is associated with a stream socket, which allows local users to cause a denial of service (system crash) by leveraging the ability to create a raw socket.

Project: linux
File: sock.c

void release_sock(struct sock *sk)
{
	/*
	 * The sk_lock has mutex_unlock() semantics:
	 */
	mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_);

	spin_lock_bh(&sk->sk_lock.slock);
	if (sk->sk_backlog.tail)
		__release_sock(sk);

	if (sk->sk_prot->release_cb)
		sk->sk_prot->release_cb(sk);

	sk->sk_lock.owned = 0;
	if (waitqueue_active(&sk->sk_lock.wq))
		wake_up(&sk->sk_lock.wq);
	spin_unlock_bh(&sk->sk_lock.slock);
}

Project: linux
File: sock.c

struct sock *sk_alloc(struct net *net, int family, gfp_t priority,
		      struct proto *prot)
{
	struct sock *sk;

	sk = sk_prot_alloc(prot, priority | __GFP_ZERO, family);
	if (sk) {
		sk->sk_family = family;
		/*
		 * See comment in struct sock definition to understand
		 * why we need sk_prot_creator -acme
		 */
		sk->sk_prot = sk->sk_prot_creator = prot;
		sock_lock_init(sk);
		sock_net_set(sk, get_net(net));
		atomic_set(&sk->sk_wmem_alloc, 1);

		sock_update_classid(sk);
		sock_update_netprioidx(sk, current);
	}

	return sk;
}

Project: linux
File: sock.c

void sk_clear_memalloc(struct sock *sk)
{
	sock_reset_flag(sk, SOCK_MEMALLOC);
	sk->sk_allocation &= ~__GFP_MEMALLOC;
	static_key_slow_dec(&memalloc_socks);

	/*
	 * SOCK_MEMALLOC is allowed to ignore rmem limits to ensure forward
	 * progress of swapping. However, if SOCK_MEMALLOC is cleared while
	 * it has rmem allocations there is a risk that the user of the
	 * socket cannot make forward progress due to exceeding the rmem
	 * limits. By rights, sk_clear_memalloc() should only be called
	 * on sockets being torn down but warn and reset the accounting if
	 * that assumption breaks.
	 */
	if (WARN_ON(sk->sk_forward_alloc))
		sk_mem_reclaim(sk);
}

Project: linux
File: sock.c

void sk_set_memalloc(struct sock *sk)
{
	sock_set_flag(sk, SOCK_MEMALLOC);
	sk->sk_allocation |= __GFP_MEMALLOC;
	static_key_slow_inc(&memalloc_socks);
}

Project: linux
File: sock.c

void sk_setup_caps(struct sock *sk, struct dst_entry *dst)
{
	__sk_dst_set(sk, dst);
	sk->sk_route_caps = dst->dev->features;
	if (sk->sk_route_caps & NETIF_F_GSO)
		sk->sk_route_caps |= NETIF_F_GSO_SOFTWARE;
	sk->sk_route_caps &= ~sk->sk_route_nocaps;
	if (sk_can_gso(sk)) {
		if (dst->header_len) {
			sk->sk_route_caps &= ~NETIF_F_GSO_MASK;
		} else {
			sk->sk_route_caps |= NETIF_F_SG | NETIF_F_HW_CSUM;
			sk->sk_gso_max_size = dst->dev->gso_max_size;
			sk->sk_gso_max_segs = dst->dev->gso_max_segs;
		}
	}
}

Project: linux
File: sock.c

struct sk_buff *sock_alloc_send_pskb(struct sock *sk, unsigned long header_len,
				     unsigned long data_len, int noblock,
				     int *errcode)
{
	struct sk_buff *skb;
	gfp_t gfp_mask;
	long timeo;
	int err;
	int npages = (data_len + (PAGE_SIZE - 1)) >> PAGE_SHIFT;

	err = -EMSGSIZE;
	if (npages > MAX_SKB_FRAGS)
		goto failure;

	gfp_mask = sk->sk_allocation;
	if (gfp_mask & __GFP_WAIT)
		gfp_mask |= __GFP_REPEAT;

	timeo = sock_sndtimeo(sk, noblock);
	while (1) {
		err = sock_error(sk);
		if (err != 0)
			goto failure;

		err = -EPIPE;
		if (sk->sk_shutdown & SEND_SHUTDOWN)
			goto failure;

		if (atomic_read(&sk->sk_wmem_alloc) < sk->sk_sndbuf) {
			skb = alloc_skb(header_len, gfp_mask);
			if (skb) {
				int i;

				/* No pages, we're done... */
				if (!data_len)
					break;

				skb->truesize += data_len;
				skb_shinfo(skb)->nr_frags = npages;
				for (i = 0; i < npages; i++) {
					struct page *page;

					page = alloc_pages(sk->sk_allocation, 0);
					if (!page) {
						err = -ENOBUFS;
						skb_shinfo(skb)->nr_frags = i;
						kfree_skb(skb);
						goto failure;
					}

					__skb_fill_page_desc(skb, i,
							page, 0,
							(data_len >= PAGE_SIZE ?
							 PAGE_SIZE :
							 data_len));
					data_len -= PAGE_SIZE;
				}

				/* Full success... */
				break;
			}
			err = -ENOBUFS;
			goto failure;
		}
		set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
		set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
		err = -EAGAIN;
		if (!timeo)
			goto failure;
		if (signal_pending(current))
			goto interrupted;
		timeo = sock_wait_for_wmem(sk, timeo);
	}

	skb_set_owner_w(skb, sk);
	return skb;

interrupted:
	err = sock_intr_errno(timeo);
failure:
	*errcode = err;
	return NULL;
}

Project: linux
File: sock.c

void sock_edemux(struct sk_buff *skb)
{
	struct sock *sk = skb->sk;

#ifdef CONFIG_INET
	if (sk->sk_state == TCP_TIME_WAIT)
		inet_twsk_put(inet_twsk(sk));
	else
#endif
		sock_put(sk);
}

Project: linux
File: sock.c

int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
{
	int err;
	int skb_len;
	unsigned long flags;
	struct sk_buff_head *list = &sk->sk_receive_queue;

	if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf) {
		atomic_inc(&sk->sk_drops);
		trace_sock_rcvqueue_full(sk, skb);
		return -ENOMEM;
	}

	err = sk_filter(sk, skb);
	if (err)
		return err;

	if (!sk_rmem_schedule(sk, skb, skb->truesize)) {
		atomic_inc(&sk->sk_drops);
		return -ENOBUFS;
	}

	skb->dev = NULL;
	skb_set_owner_r(skb, sk);

	/* Cache the SKB length before we tack it onto the receive
	 * queue.  Once it is added it no longer belongs to us and
	 * may be freed by other threads of control pulling packets
	 * from the queue.
	 */
	skb_len = skb->len;

	/* we escape from rcu protected region, make sure we dont leak
	 * a norefcounted dst
	 */
	skb_dst_force(skb);

	spin_lock_irqsave(&list->lock, flags);
	skb->dropcount = atomic_read(&sk->sk_drops);
	__skb_queue_tail(list, skb);
	spin_unlock_irqrestore(&list->lock, flags);

	if (!sock_flag(sk, SOCK_DEAD))
		sk->sk_data_ready(sk, skb_len);
	return 0;
}

Project: linux
File: sock.c

void sock_update_netprioidx(struct sock *sk, struct task_struct *task)
{
	if (in_interrupt())
		return;

	sk->sk_cgrp_prioidx = task_netprioidx(task);
}