From 9ed988cd591500c040b2a6257bc68543e08ceeef Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Wed, 9 Mar 2016 21:58:34 -0500 Subject: [PATCH] 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 9c7077622dd9 ("packet: make packet_snd fail on len smaller than l2 header") Signed-off-by: Willem de Bruijn Signed-off-by: David S. Miller --- net/packet/af_packet.c | 43 ++++++++++++++++++------------------------ 1 file changed, 18 insertions(+), 25 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index d41b1074cb2d..1ecfa710ca98 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -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) && -- 2.20.1