netfilter: ebtables: Fixes dropping of small packets in bridge nat

Fixes an error causing small packets to get dropped. skb_ensure_writable
expects the second parameter to be a length in the ethernet payload.=20
If we want to write the ethernet header (src, dst), we should pass 0.
Otherwise, packets with small payloads (< ETH_ALEN) will get dropped.

Fixes: c1a8311679 ("netfilter: bridge: convert skb_make_writable to skb_ensure_writable")
Signed-off-by: Timothée COCAULT <timothee.cocault@orange.com>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Timothée COCAULT 2020-10-14 12:36:15 +00:00 committed by Pablo Neira Ayuso
parent 68f9f9c2c3
commit 63137bc588
3 changed files with 3 additions and 3 deletions

View File

@ -21,7 +21,7 @@ ebt_dnat_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
const struct ebt_nat_info *info = par->targinfo;
if (skb_ensure_writable(skb, ETH_ALEN))
if (skb_ensure_writable(skb, 0))
return EBT_DROP;
ether_addr_copy(eth_hdr(skb)->h_dest, info->mac);

View File

@ -21,7 +21,7 @@ ebt_redirect_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
const struct ebt_redirect_info *info = par->targinfo;
if (skb_ensure_writable(skb, ETH_ALEN))
if (skb_ensure_writable(skb, 0))
return EBT_DROP;
if (xt_hooknum(par) != NF_BR_BROUTING)

View File

@ -22,7 +22,7 @@ ebt_snat_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
const struct ebt_nat_info *info = par->targinfo;
if (skb_ensure_writable(skb, ETH_ALEN * 2))
if (skb_ensure_writable(skb, 0))
return EBT_DROP;
ether_addr_copy(eth_hdr(skb)->h_source, info->mac);