tcp: fix SCM_TIMESTAMPING_OPT_STATS for normal skbs

__sock_recv_timestamp can be called for both normal skbs (for
receive timestamps) and for skbs on the error queue (for transmit
timestamps).

Commit 1c885808e456
(tcp: SOF_TIMESTAMPING_OPT_STATS option for SO_TIMESTAMPING)
assumes any skb passed to __sock_recv_timestamp are from
the error queue, containing OPT_STATS in the content of the skb.
This results in accessing invalid memory or generating junk
data.

To fix this, set skb->pkt_type to PACKET_OUTGOING for packets
on the error queue. This is safe because on the receive path
on local sockets skb->pkt_type is never set to PACKET_OUTGOING.
With that, copy OPT_STATS from a packet, only if its pkt_type
is PACKET_OUTGOING.

Fixes: 1c885808e456 ("tcp: SOF_TIMESTAMPING_OPT_STATS option for SO_TIMESTAMPING")
Reported-by: JongHwan Kim <zzoru007@gmail.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
{
	struct sk_buff_fclones *fclones = container_of(skb,
						       struct sk_buff_fclones,
						       skb1);
	struct sk_buff *n;

	if (skb_orphan_frags(skb, gfp_mask))
		return NULL;

	if (skb->fclone == SKB_FCLONE_ORIG &&
	    atomic_read(&fclones->fclone_ref) == 1) {
		n = &fclones->skb2;
		atomic_set(&fclones->fclone_ref, 2);
	} else {
		if (skb_pfmemalloc(skb))
			gfp_mask |= __GFP_MEMALLOC;

		n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
		if (!n)
			return NULL;

		kmemcheck_annotate_bitfield(n, flags1);
		n->fclone = SKB_FCLONE_UNAVAILABLE;
	}

	return __skb_clone(n, skb);
}

struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
{
	struct sk_buff_fclones *fclones = container_of(skb,
						       struct sk_buff_fclones,
						       skb1);
	struct sk_buff *n;

	if (skb_orphan_frags(skb, gfp_mask))
		return NULL;

	if (skb->fclone == SKB_FCLONE_ORIG &&
	    atomic_read(&fclones->fclone_ref) == 1) {
		n = &fclones->skb2;
		atomic_set(&fclones->fclone_ref, 2);
	} else {
		if (skb_pfmemalloc(skb))
			gfp_mask |= __GFP_MEMALLOC;

		n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
		if (!n)
			return NULL;

		kmemcheck_annotate_bitfield(n, flags1);
		n->fclone = SKB_FCLONE_UNAVAILABLE;
	}

	return __skb_clone(n, skb);
}
