From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Cc: davem@davemloft.net, netdev@vger.kernel.org
Subject: [PATCH 2/8] netfilter: nf_tables: Make nft_meta expression more robust
Date: Wed, 31 Jul 2019 13:51:51 +0200 [thread overview]
Message-ID: <20190731115157.27020-3-pablo@netfilter.org> (raw)
In-Reply-To: <20190731115157.27020-1-pablo@netfilter.org>
From: Phil Sutter <phil@nwl.cc>
nft_meta_get_eval()'s tendency to bail out setting NFT_BREAK verdict in
situations where required data is missing leads to unexpected behaviour
with inverted checks like so:
| meta iifname != eth0 accept
This rule will never match if there is no input interface (or it is not
known) which is not intuitive and, what's worse, breaks consistency of
iptables-nft with iptables-legacy.
Fix this by falling back to placing a value in dreg which never matches
(avoiding accidental matches), i.e. zero for interface index and an
empty string for interface name.
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
net/bridge/netfilter/nft_meta_bridge.c | 6 +-----
net/netfilter/nft_meta.c | 16 ++++------------
2 files changed, 5 insertions(+), 17 deletions(-)
diff --git a/net/bridge/netfilter/nft_meta_bridge.c b/net/bridge/netfilter/nft_meta_bridge.c
index bed66f536b34..a98dec2cf0cf 100644
--- a/net/bridge/netfilter/nft_meta_bridge.c
+++ b/net/bridge/netfilter/nft_meta_bridge.c
@@ -30,13 +30,9 @@ static void nft_meta_bridge_get_eval(const struct nft_expr *expr,
switch (priv->key) {
case NFT_META_BRI_IIFNAME:
br_dev = nft_meta_get_bridge(in);
- if (!br_dev)
- goto err;
break;
case NFT_META_BRI_OIFNAME:
br_dev = nft_meta_get_bridge(out);
- if (!br_dev)
- goto err;
break;
case NFT_META_BRI_IIFPVID: {
u16 p_pvid;
@@ -64,7 +60,7 @@ static void nft_meta_bridge_get_eval(const struct nft_expr *expr,
goto out;
}
- strncpy((char *)dest, br_dev->name, IFNAMSIZ);
+ strncpy((char *)dest, br_dev ? br_dev->name : "", IFNAMSIZ);
return;
out:
return nft_meta_get_eval(expr, regs, pkt);
diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c
index f1b1d948c07b..f69afb9ff3cb 100644
--- a/net/netfilter/nft_meta.c
+++ b/net/netfilter/nft_meta.c
@@ -60,24 +60,16 @@ void nft_meta_get_eval(const struct nft_expr *expr,
*dest = skb->mark;
break;
case NFT_META_IIF:
- if (in == NULL)
- goto err;
- *dest = in->ifindex;
+ *dest = in ? in->ifindex : 0;
break;
case NFT_META_OIF:
- if (out == NULL)
- goto err;
- *dest = out->ifindex;
+ *dest = out ? out->ifindex : 0;
break;
case NFT_META_IIFNAME:
- if (in == NULL)
- goto err;
- strncpy((char *)dest, in->name, IFNAMSIZ);
+ strncpy((char *)dest, in ? in->name : "", IFNAMSIZ);
break;
case NFT_META_OIFNAME:
- if (out == NULL)
- goto err;
- strncpy((char *)dest, out->name, IFNAMSIZ);
+ strncpy((char *)dest, out ? out->name : "", IFNAMSIZ);
break;
case NFT_META_IIFTYPE:
if (in == NULL)
--
2.11.0
next prev parent reply other threads:[~2019-07-31 11:52 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-31 11:51 [PATCH 0/8] netfilter fixes for net Pablo Neira Ayuso
2019-07-31 11:51 ` [PATCH 1/8] netfilter: ebtables: fix a memory leak bug in compat Pablo Neira Ayuso
2019-07-31 11:51 ` Pablo Neira Ayuso [this message]
2019-07-31 11:51 ` [PATCH 3/8] netfilter: nft_meta_bridge: Eliminate 'out' label Pablo Neira Ayuso
2019-07-31 11:51 ` [PATCH 4/8] netfilter: add include guard to xt_connlabel.h Pablo Neira Ayuso
2019-07-31 11:51 ` [PATCH 5/8] netfilter: ipset: Actually allow destination MAC address for hash:ip,mac sets too Pablo Neira Ayuso
2019-07-31 11:51 ` [PATCH 6/8] netfilter: ipset: Copy the right MAC address in bitmap:ip,mac and hash:ip,mac sets Pablo Neira Ayuso
2019-07-31 11:51 ` [PATCH 7/8] netfilter: ipset: Fix rename concurrency with listing Pablo Neira Ayuso
2019-07-31 11:51 ` [PATCH 8/8] netfilter: ebtables: also count base chain policies Pablo Neira Ayuso
2019-07-31 15:50 ` [PATCH 0/8] netfilter fixes for net David Miller
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