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packet: validate variable length ll headers 

Replace link layer header validation check ll_header_truncate with
more generic dev_validate_header.

Validation based on hard_header_len incorrectly drops valid packets
in variable length protocols, such as AX25. dev_validate_header
calls header_ops.validate for such protocols to ensure correctness
below hard_header_len.

See also http://comments.gmane.org/gmane.linux.network/401064

Fixes 9c7077622d ("packet: make packet_snd fail on len smaller than l2 header")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Willem de Bruijn 2016-03-09 21:58:34 -05:00 committed by David S. Miller
parent ea47781c26
commit 9ed988cd59
1 changed files with 18 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

43
net/packet/af_packet.c
View File

@ -1915,6 +1915,10 @@ retry:
goto retry;
}
if (!dev_validate_header(dev, skb->data, len)) {
err = -EINVAL;
goto out_unlock;
}
if (len > (dev->mtu + dev->hard_header_len + extra_len) &&
!packet_extra_vlan_len_allowed(dev, skb)) {
err = -EMSGSIZE;
@ -2393,18 +2397,6 @@ static void tpacket_destruct_skb(struct sk_buff *skb)
sock_wfree(skb);
}
static bool ll_header_truncated(const struct net_device *dev, int len)
{
/* net device doesn't like empty head */
if (unlikely(len < dev->hard_header_len)) {
net_warn_ratelimited("%s: packet size is too short (%d < %d)\n",
current->comm, len, dev->hard_header_len);
return true;
}
return false;
}
static void tpacket_set_protocol(const struct net_device *dev,
struct sk_buff *skb)
{
@ -2522,16 +2514,20 @@ static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,
if (unlikely(err < 0))
return -EINVAL;
} else if (copylen) {
int hdrlen = min_t(int, copylen, tp_len);
skb_push(skb, dev->hard_header_len);
skb_put(skb, copylen - dev->hard_header_len);
err = skb_store_bits(skb, 0, data, copylen);
err = skb_store_bits(skb, 0, data, hdrlen);
if (unlikely(err))
return err;
if (!dev_validate_header(dev, skb->data, hdrlen))
return -EINVAL;
if (!skb->protocol)
tpacket_set_protocol(dev, skb);
data += copylen;
to_write -= copylen;
data += hdrlen;
to_write -= hdrlen;
}
offset = offset_in_page(data);
@ -2703,13 +2699,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
copylen = __virtio16_to_cpu(vio_le(),
vnet_hdr->hdr_len);
}
if (dev->hard_header_len) {
if (ll_header_truncated(dev, tp_len)) {
tp_len = -EINVAL;
goto tpacket_error;
}
copylen = max_t(int, copylen, dev->hard_header_len);
}
copylen = max_t(int, copylen, dev->hard_header_len);
skb = sock_alloc_send_skb(&po->sk,
hlen + tlen + sizeof(struct sockaddr_ll) +
(copylen - dev->hard_header_len),
@ -2905,9 +2895,6 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
offset = dev_hard_header(skb, dev, ntohs(proto), addr, NULL, len);
if (unlikely(offset < 0))
goto out_free;
} else {
if (ll_header_truncated(dev, len))
goto out_free;
}
/* Returns -EFAULT on error */
@ -2915,6 +2902,12 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
if (err)
goto out_free;
if (sock->type == SOCK_RAW &&
!dev_validate_header(dev, skb->data, len)) {
err = -EINVAL;
goto out_free;
}
sock_tx_timestamp(sk, &skb_shinfo(skb)->tx_flags);
if (!vnet_hdr.gso_type && (len > dev->mtu + reserve + extra_len) &&