On Fri, Mar 4, 2016 at 3:44 PM, Willem de Bruijn <willemdebruijn.ker...@gmail.com> wrote: > From: Willem de Bruijn <will...@google.com> > > 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 <will...@google.com> > --- > 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 >