Patchwork [2/2,v2] netfilter: nf_tables: fix oops when using gotos

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Submitter Pablo Neira
Date Feb. 7, 2014, 4:29 p.m.
Message ID <1391790598-5390-2-git-send-email-pablo@netfilter.org>
Download mbox | patch
Permalink /patch/318106/
State Superseded
Headers show

Comments

Pablo Neira - Feb. 7, 2014, 4:29 p.m.
Fix an oops if you use the "goto" operation, you will end up in
non-base chain with no counters and no default policy.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
v2: recover inline to nft_chain_stats.

 net/netfilter/nf_tables_core.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)
Patrick McHardy - Feb. 7, 2014, 4:34 p.m.
On Fri, Feb 07, 2014 at 05:29:58PM +0100, Pablo Neira Ayuso wrote:
> Fix an oops if you use the "goto" operation, you will end up in
> non-base chain with no counters and no default policy.
> 
> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> ---
> v2: recover inline to nft_chain_stats.
> 
>  net/netfilter/nf_tables_core.c |   11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/net/netfilter/nf_tables_core.c b/net/netfilter/nf_tables_core.c
> index 0d879fc..13fecde 100644
> --- a/net/netfilter/nf_tables_core.c
> +++ b/net/netfilter/nf_tables_core.c
> @@ -67,18 +67,24 @@ struct nft_jumpstack {
>  	int			rulenum;
>  };
>  
> -static inline void
> +static inline int
>  nft_chain_stats(const struct nft_chain *this, const struct nft_pktinfo *pkt,
>  		struct nft_jumpstack *jumpstack, unsigned int stackptr)
>  {
>  	struct nft_stats __percpu *stats;
>  	const struct nft_chain *chain = stackptr ? jumpstack[0].chain : this;
>  
> +	/* You can reach this through goto chain */
> +	if (!(chain->flags & NFT_BASE_CHAIN))
> +		return NF_ACCEPT;
> +
>  	rcu_read_lock_bh();
>  	stats = rcu_dereference(nft_base_chain(chain)->stats);
>  	__this_cpu_inc(stats->pkts);
>  	__this_cpu_add(stats->bytes, pkt->skb->len);
>  	rcu_read_unlock_bh();
> +
> +	return nft_base_chain(chain)->policy;
>  }
>  
>  enum nft_trace {
> @@ -209,12 +215,11 @@ next_rule:
>  		rulenum = jumpstack[stackptr].rulenum;
>  		goto next_rule;
>  	}
> -	nft_chain_stats(chain, pkt, jumpstack, stackptr);
>  
>  	if (unlikely(pkt->skb->nf_trace))
>  		nft_trace_packet(pkt, chain, ++rulenum, NFT_TRACE_POLICY);
>  
> -	return nft_base_chain(chain)->policy;
> +	return nft_chain_stats(chain, pkt, jumpstack, stackptr);

I think we should just inline the function manually, it doesn't help
readability to have it take care of goto-specific cases and handle
verdicts/policies.

Also, what about NFT_TRACE_POLICY for the goto case? Should be generate
a message even through there is no policy?
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Patch

diff --git a/net/netfilter/nf_tables_core.c b/net/netfilter/nf_tables_core.c
index 0d879fc..13fecde 100644
--- a/net/netfilter/nf_tables_core.c
+++ b/net/netfilter/nf_tables_core.c
@@ -67,18 +67,24 @@  struct nft_jumpstack {
 	int			rulenum;
 };
 
-static inline void
+static inline int
 nft_chain_stats(const struct nft_chain *this, const struct nft_pktinfo *pkt,
 		struct nft_jumpstack *jumpstack, unsigned int stackptr)
 {
 	struct nft_stats __percpu *stats;
 	const struct nft_chain *chain = stackptr ? jumpstack[0].chain : this;
 
+	/* You can reach this through goto chain */
+	if (!(chain->flags & NFT_BASE_CHAIN))
+		return NF_ACCEPT;
+
 	rcu_read_lock_bh();
 	stats = rcu_dereference(nft_base_chain(chain)->stats);
 	__this_cpu_inc(stats->pkts);
 	__this_cpu_add(stats->bytes, pkt->skb->len);
 	rcu_read_unlock_bh();
+
+	return nft_base_chain(chain)->policy;
 }
 
 enum nft_trace {
@@ -209,12 +215,11 @@  next_rule:
 		rulenum = jumpstack[stackptr].rulenum;
 		goto next_rule;
 	}
-	nft_chain_stats(chain, pkt, jumpstack, stackptr);
 
 	if (unlikely(pkt->skb->nf_trace))
 		nft_trace_packet(pkt, chain, ++rulenum, NFT_TRACE_POLICY);
 
-	return nft_base_chain(chain)->policy;
+	return nft_chain_stats(chain, pkt, jumpstack, stackptr);
 }
 EXPORT_SYMBOL_GPL(nft_do_chain);