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| author | Michal Kubeček <mkubecek@suse.cz> | 2015-03-02 18:27:11 +0100 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2015-03-12 10:06:28 +0100 |
| commit | 4f9586428f533c47478f73cfedbc13f0610b2db9 (patch) | |
| tree | d058a5c9e3c71ce0bd2d23c316b4b06344faafc4 /net/ipv4/ip_output.c | |
| parent | b207adc1d085769c9cee16925bc2d7827bcc4a94 (diff) | |
| download | lwn-4f9586428f533c47478f73cfedbc13f0610b2db9.tar.gz lwn-4f9586428f533c47478f73cfedbc13f0610b2db9.zip | |
udp: only allow UFO for packets from SOCK_DGRAM sockets
[ Upstream commit acf8dd0a9d0b9e4cdb597c2f74802f79c699e802 ]
If an over-MTU UDP datagram is sent through a SOCK_RAW socket to a
UFO-capable device, ip_ufo_append_data() sets skb->ip_summed to
CHECKSUM_PARTIAL unconditionally as all GSO code assumes transport layer
checksum is to be computed on segmentation. However, in this case,
skb->csum_start and skb->csum_offset are never set as raw socket
transmit path bypasses udp_send_skb() where they are usually set. As a
result, driver may access invalid memory when trying to calculate the
checksum and store the result (as observed in virtio_net driver).
Moreover, the very idea of modifying the userspace provided UDP header
is IMHO against raw socket semantics (I wasn't able to find a document
clearly stating this or the opposite, though). And while allowing
CHECKSUM_NONE in the UFO case would be more efficient, it would be a bit
too intrusive change just to handle a corner case like this. Therefore
disallowing UFO for packets from SOCK_DGRAM seems to be the best option.
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Diffstat (limited to 'net/ipv4/ip_output.c')
| -rw-r--r-- | net/ipv4/ip_output.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 52e82e1709e6..b4cdc79a7fc8 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -842,7 +842,8 @@ static int __ip_append_data(struct sock *sk, cork->length += length; if (((length > mtu) || (skb && skb_is_gso(skb))) && (sk->sk_protocol == IPPROTO_UDP) && - (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) { + (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len && + (sk->sk_type == SOCK_DGRAM)) { err = ip_ufo_append_data(sk, queue, getfrag, from, length, hh_len, fragheaderlen, transhdrlen, maxfraglen, flags); |