From 127917c29a432c3b798e014a1714e9c1af0f87fe Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Mon, 27 Oct 2014 14:08:17 +0100 Subject: netfilter: nft_reject_bridge: restrict reject to prerouting and input Restrict the reject expression to the prerouting and input bridge hooks. If we allow this to be used from forward or any other later bridge hook, if the frame is flooded to several ports, we'll end up sending several reject packets, one per cloned packet. Signed-off-by: Pablo Neira Ayuso --- net/bridge/netfilter/nft_reject_bridge.c | 33 +++++++++++++++++++++++++++++++- 1 file changed, 32 insertions(+), 1 deletion(-) (limited to 'net/bridge') diff --git a/net/bridge/netfilter/nft_reject_bridge.c b/net/bridge/netfilter/nft_reject_bridge.c index 31b27e1..654c901 100644 --- a/net/bridge/netfilter/nft_reject_bridge.c +++ b/net/bridge/netfilter/nft_reject_bridge.c @@ -18,6 +18,7 @@ #include #include #include +#include #include "../br_private.h" static void nft_reject_br_push_etherhdr(struct sk_buff *oldskb, @@ -305,12 +306,34 @@ out: data[NFT_REG_VERDICT].verdict = NF_DROP; } +static int nft_reject_bridge_validate_hooks(const struct nft_chain *chain) +{ + struct nft_base_chain *basechain; + + if (chain->flags & NFT_BASE_CHAIN) { + basechain = nft_base_chain(chain); + + switch (basechain->ops[0].hooknum) { + case NF_BR_PRE_ROUTING: + case NF_BR_LOCAL_IN: + break; + default: + return -EOPNOTSUPP; + } + } + return 0; +} + static int nft_reject_bridge_init(const struct nft_ctx *ctx, const struct nft_expr *expr, const struct nlattr * const tb[]) { struct nft_reject *priv = nft_expr_priv(expr); - int icmp_code; + int icmp_code, err; + + err = nft_reject_bridge_validate_hooks(ctx->chain); + if (err < 0) + return err; if (tb[NFTA_REJECT_TYPE] == NULL) return -EINVAL; @@ -359,6 +382,13 @@ nla_put_failure: return -1; } +static int nft_reject_bridge_validate(const struct nft_ctx *ctx, + const struct nft_expr *expr, + const struct nft_data **data) +{ + return nft_reject_bridge_validate_hooks(ctx->chain); +} + static struct nft_expr_type nft_reject_bridge_type; static const struct nft_expr_ops nft_reject_bridge_ops = { .type = &nft_reject_bridge_type, @@ -366,6 +396,7 @@ static const struct nft_expr_ops nft_reject_bridge_ops = { .eval = nft_reject_bridge_eval, .init = nft_reject_bridge_init, .dump = nft_reject_bridge_dump, + .validate = nft_reject_bridge_validate, }; static struct nft_expr_type nft_reject_bridge_type __read_mostly = { -- cgit v1.1