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authorPhil Sutter <phil@nwl.cc>2019-07-23 15:27:52 +0200
committerPablo Neira Ayuso <pablo@netfilter.org>2019-07-25 08:37:20 +0200
commitcb81572e8cb50c5fb98b0b962cdfe48fff71fd37 (patch)
treea6d4fa40c2d04babdc5fd076295d0144f664979d /net/bridge
parent15a78ba1844a8e052c1226f930133de4cef4e7ad (diff)
netfilter: nf_tables: Make nft_meta expression more robust
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>
Diffstat (limited to 'net/bridge')
-rw-r--r--net/bridge/netfilter/nft_meta_bridge.c6
1 files changed, 1 insertions, 5 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);