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| author | Cong Wang <xiyou.wangcong@gmail.com> | 2020-10-12 16:17:21 -0700 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2020-10-13 18:35:29 -0700 |
| commit | fdafed459998e2be0e877e6189b24cb7a0183224 (patch) | |
| tree | 7b4f6180adf6214fe2e521460baa4727c7551087 /net | |
| parent | 4e3bbb33e6f36e4b05be1b1b9b02e3dd5aaa3e69 (diff) | |
| download | linux-fdafed459998e2be0e877e6189b24cb7a0183224.tar.bz2 | |
ip_gre: set dev->hard_header_len and dev->needed_headroom properly
GRE tunnel has its own header_ops, ipgre_header_ops, and sets it
conditionally. When it is set, it assumes the outer IP header is
already created before ipgre_xmit().
This is not true when we send packets through a raw packet socket,
where L2 headers are supposed to be constructed by user. Packet
socket calls dev_validate_header() to validate the header. But
GRE tunnel does not set dev->hard_header_len, so that check can
be simply bypassed, therefore uninit memory could be passed down
to ipgre_xmit(). Similar for dev->needed_headroom.
dev->hard_header_len is supposed to be the length of the header
created by dev->header_ops->create(), so it should be used whenever
header_ops is set, and dev->needed_headroom should be used when it
is not set.
Reported-and-tested-by: syzbot+4a2c52677a8a1aa283cb@syzkaller.appspotmail.com
Cc: William Tu <u9012063@gmail.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Xie He <xie.he.0141@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/ip_gre.c | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index 4e31f23e4117..e70291748889 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -625,9 +625,7 @@ static netdev_tx_t ipgre_xmit(struct sk_buff *skb, } if (dev->header_ops) { - /* Need space for new headers */ - if (skb_cow_head(skb, dev->needed_headroom - - (tunnel->hlen + sizeof(struct iphdr)))) + if (skb_cow_head(skb, 0)) goto free_skb; tnl_params = (const struct iphdr *)skb->data; @@ -748,7 +746,11 @@ static void ipgre_link_update(struct net_device *dev, bool set_mtu) len = tunnel->tun_hlen - len; tunnel->hlen = tunnel->hlen + len; - dev->needed_headroom = dev->needed_headroom + len; + if (dev->header_ops) + dev->hard_header_len += len; + else + dev->needed_headroom += len; + if (set_mtu) dev->mtu = max_t(int, dev->mtu - len, 68); @@ -944,6 +946,7 @@ static void __gre_tunnel_init(struct net_device *dev) tunnel->parms.iph.protocol = IPPROTO_GRE; tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen; + dev->needed_headroom = tunnel->hlen + sizeof(tunnel->parms.iph); dev->features |= GRE_FEATURES; dev->hw_features |= GRE_FEATURES; @@ -987,10 +990,14 @@ static int ipgre_tunnel_init(struct net_device *dev) return -EINVAL; dev->flags = IFF_BROADCAST; dev->header_ops = &ipgre_header_ops; + dev->hard_header_len = tunnel->hlen + sizeof(*iph); + dev->needed_headroom = 0; } #endif } else if (!tunnel->collect_md) { dev->header_ops = &ipgre_header_ops; + dev->hard_header_len = tunnel->hlen + sizeof(*iph); + dev->needed_headroom = 0; } return ip_tunnel_init(dev); |