[PATCH net 2/3] packet: validate variable length ll headers
From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Date: 2016-03-04 20:44:25
Also in:
linux-hams
Subsystem:
networking [general], packet sockets, the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Willem de Bruijn, Linus Torvalds
From: Willem de Bruijn <willemb@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 Signed-off-by: Willem de Bruijn <willemb@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