Re: [PATCH 7/7] netfilter: nf_ct_helper: Fix logging for dropped packets

On Tue, 2013-02-19 at 02:50 +0100, Pablo Neira Ayuso wrote:

On Mon, Feb 18, 2013 at 05:33:14PM -0800, Joe Perches wrote:

quoted

On Tue, 2013-02-19 at 02:11 +0100, Pablo Neira Ayuso wrote:

quoted

On Mon, Feb 18, 2013 at 04:22:02PM -0800, Joe Perches wrote:

quoted

On Tue, 2013-02-19 at 01:10 +0100, pablo@netfilter.org wrote:

quoted

This patch modifies the existing code to provide more specific
error message in the scope of each helper to help users to debug
the reason why the packet has been dropped, ie:

[]

quoted

diff --git a/include/net/netfilter/nf_conntrack_helper.h b/include/net/netfilter/nf_conntrack_helper.h

[]

quoted

@@ -100,6 +100,9 @@ struct nf_ct_helper_expectfn {
 	void (*expectfn)(struct nf_conn *ct, struct nf_conntrack_expect *exp);
 };
 
+extern void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *,
+			     const char *fmt, ...);

Hi again Pablo.

Sorry, I didn't look at the function implementation.

It doesn't use the var args that follow fmt.
Two current uses have format and args aren't emitted correctly.

This is needed:

From: Joe Perches <joe@perches.com>

Update nf_ct_helper_log to emit args along with the format.

Signed-off-by: Joe Perches <joe@perches.com>
---
 net/netfilter/nf_conntrack_helper.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
index 013cdf6..3ebc2ae 100644
--- a/net/netfilter/nf_conntrack_helper.c
+++ b/net/netfilter/nf_conntrack_helper.c

@@ -341,6 +341,13 @@ void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *ct,
 {
 	const struct nf_conn_help *help;
 	const struct nf_conntrack_helper *helper;
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+
+	vaf.fmt = fmt;
+	vaf.va = &args;
 
 	/* Called from the helper function, this call never fails */
 	help = nfct_help(ct);

@@ -349,7 +356,9 @@ void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *ct,
 	helper = rcu_dereference(help->helper);
 
 	nf_log_packet(nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL,
-		      "nf_ct_%s: dropping packet: %s ", helper->name, fmt);
+		      "nf_ct_%s: dropping packet: %pV", helper->name, &vaf);
+
+	va_end(args);
 }
 EXPORT_SYMBOL_GPL(nf_ct_helper_log);