From: Timothée COCAULT Date: Wed, 14 Oct 2020 12:36:15 +0000 (+0000) Subject: netfilter: ebtables: Fixes dropping of small packets in bridge nat X-Git-Tag: v5.10-rc1~40^2~2^2~3 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=63137bc5882a1882c553d389fdeeeace86ee1741;p=thirdparty%2Fkernel%2Flinux.git 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: c1a831167901 ("netfilter: bridge: convert skb_make_writable to skb_ensure_writable") Signed-off-by: Timothée COCAULT Reviewed-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- diff --git a/net/bridge/netfilter/ebt_dnat.c b/net/bridge/netfilter/ebt_dnat.c index 12a4f4d936810..3fda71a8579d1 100644 --- a/net/bridge/netfilter/ebt_dnat.c +++ b/net/bridge/netfilter/ebt_dnat.c @@ -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); diff --git a/net/bridge/netfilter/ebt_redirect.c b/net/bridge/netfilter/ebt_redirect.c index 0cad62a4052b9..307790562b492 100644 --- a/net/bridge/netfilter/ebt_redirect.c +++ b/net/bridge/netfilter/ebt_redirect.c @@ -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) diff --git a/net/bridge/netfilter/ebt_snat.c b/net/bridge/netfilter/ebt_snat.c index 27443bf229a3b..7dfbcdfc30e5d 100644 --- a/net/bridge/netfilter/ebt_snat.c +++ b/net/bridge/netfilter/ebt_snat.c @@ -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);