[PATCH net 07/14] netfilter: nft_compat: ebtables emulation must reject non-bridge targets
From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: 2026-06-23 22:16:04
Also in:
netfilter-devel
Subsystem:
netfilter, networking [general], the rest · Maintainers:
Pablo Neira Ayuso, Florian Westphal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From: Florian Westphal <fw@strlen.de>
xtables targets return netfilter verdicts: NF_ACCEPT, NF_DROP, and so
on. ebtables targets return incompatible verdicts: EBT_ACCEPT,
EBT_DROP, ... We cannot allow fallback to NFPROTO_UNSPEC.
ebtables doesn't permit this since
11ff7288beb2 ("netfilter: ebtables: reject non-bridge targets")
but that commit missed the nft_compat layer.
Reported-by: Ren Wei <redacted>
Reported-by: Wyatt Feng <redacted>
Reported-by: Yuan Tan <redacted>
Reported-by: Yifan Wu <redacted>
Reported-by: Juefei Pu <redacted>
Reported-by: Zhengchuan Liang <redacted>
Reported-by: Xin Liu <redacted>
Fixes: 0ca743a55991 ("netfilter: nf_tables: add compatibility layer for x_tables")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
net/netfilter/nft_compat.c | 24 +++++++++++++++++++++---
1 file changed, 21 insertions(+), 3 deletions(-)
diff --git a/net/netfilter/nft_compat.c b/net/netfilter/nft_compat.c
index 0caa9304d2d0..63864b928259 100644
--- a/net/netfilter/nft_compat.c
+++ b/net/netfilter/nft_compat.c@@ -397,6 +397,22 @@ static int nft_target_validate(const struct nft_ctx *ctx, return 0; } +static int nft_target_bridge_validate(const struct nft_ctx *ctx, + const struct nft_expr *expr) +{ + struct xt_target *target = expr->ops->data; + + /* Do not allow UNSPEC to stand-in for NFPROTO_BRIDGE + * targets: they are incompatible. ebtables targets return + * EBT_ACCEPT, DROP and so on which are not compatible with + * NF_ACCEPT, NF_DROP and so on. + */ + if (target->family != NFPROTO_BRIDGE) + return -ENOENT; + + return nft_target_validate(ctx, expr); +} + static void __nft_match_eval(const struct nft_expr *expr, struct nft_regs *regs, const struct nft_pktinfo *pkt,
@@ -932,13 +948,15 @@ nft_target_select_ops(const struct nft_ctx *ctx, ops->init = nft_target_init; ops->destroy = nft_target_destroy; ops->dump = nft_target_dump; - ops->validate = nft_target_validate; ops->data = target; - if (family == NFPROTO_BRIDGE) + if (family == NFPROTO_BRIDGE) { ops->eval = nft_target_eval_bridge; - else + ops->validate = nft_target_bridge_validate; + } else { ops->eval = nft_target_eval_xt; + ops->validate = nft_target_validate; + } return ops; err:
--
2.47.3