On Fri, Mar 4, 2016 at 3:44 PM, Willem de Bruijn
<[email protected]> wrote:
> From: Willem de Bruijn <[email protected]>
>
> 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
Forgot to add
Fixes 9c7077622dd9 ("packet: make packet_snd fail on len smaller
than l2 header")
This patch, if submitted to net, will have non-trivial merge conflicts
with net-next due to
1d036d25e560 ("packet: tpacket_snd gso and checksum offload")
I maintain a patchset on top of net-next. Can send that to supersede
this one to resolve it (at the cost of only fixing the bug in the later
kernel version).
> Signed-off-by: Willem de Bruijn <[email protected]>
> ---
> net/packet/af_packet.c | 38 +++++++++++++++++---------------------
> 1 file changed, 17 insertions(+), 21 deletions(-)
>
> diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
> index 992396a..488678a 100644
> --- a/net/packet/af_packet.c
> +++ b/net/packet/af_packet.c
> @@ -1916,6 +1916,10 @@ 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;
> @@ -2326,18 +2330,6 @@ 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)
> {
> @@ -2420,14 +2412,14 @@ static int tpacket_fill_skb(struct packet_sock *po,
> struct sk_buff *skb,
> if (unlikely(err < 0))
> return -EINVAL;
> } else if (dev->hard_header_len) {
> - if (ll_header_truncated(dev, tp_len))
> - return -EINVAL;
> + int hhlen = min_t(int, dev->hard_header_len, tp_len);
>
> skb_push(skb, dev->hard_header_len);
> - err = skb_store_bits(skb, 0, data,
> - dev->hard_header_len);
> + err = skb_store_bits(skb, 0, data, hhlen);
> if (unlikely(err))
> return err;
> + if (!dev_validate_header(dev, skb->data, hhlen))
> + return -EINVAL;
> if (!skb->protocol)
> tpacket_set_protocol(dev, skb);
>
> @@ -2758,14 +2750,12 @@ static int packet_snd(struct socket *sock, struct
> msghdr *msg, size_t len)
>
> skb_set_network_header(skb, reserve);
>
> - err = -EINVAL;
> if (sock->type == SOCK_DGRAM) {
> 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))
> + if (unlikely(offset < 0)) {
> + err = -EINVAL;
> goto out_free;
> + }
> }
>
> /* Returns -EFAULT on error */
> @@ -2773,6 +2763,12 @@ 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 (!gso_type && (len > dev->mtu + reserve + extra_len) &&
> --
> 2.7.0.rc3.207.g0ac5344
>
--
To unsubscribe from this list: send the line "unsubscribe linux-hams" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
