netfilter: log: nf_log_packet() as real unified interface

Before this patch, the nf_loginfo parameter specified the logging
configuration in case the specified default logger was loaded. This
patch updates the semantics of the nf_loginfo parameter in
nf_log_packet() which now indicates the logger that you explicitly
want to use.

Thus, nf_log_packet() is exposed as an unified interface which
internally routes the log message to the corresponding logger type
by family.

The module dependencies are expressed by the new nf_logger_find_get()
and nf_logger_put() functions which bump the logger module refcount.
Thus, you can not remove logger modules that are used by rules anymore.

Another important effect of this change is that the family specific
module is only loaded when required. Therefore, xt_LOG and nft_log
will just trigger the autoload of the nf_log_{ip,ip6} modules
according to the family.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 10 insertions, 12 deletions

diff --git a/net/netfilter/xt_LOG.c b/net/netfilter/xt_LOG.c
index 5a6bd60e20d6..00eb49196e75 100644
--- a/net/netfilter/xt_LOG.c
+++ b/net/netfilter/xt_LOG.c
@@ -39,17 +39,8 @@ log_tg(struct sk_buff *skb, const struct xt_action_param *par)
 	li.u.log.level = loginfo->level;
 	li.u.log.logflags = loginfo->logflags;
 
-	if (par->family == NFPROTO_IPV4)
-		nf_log_ip_packet(net, NFPROTO_IPV4, par->hooknum, skb, par->in,
-			         par->out, &li, loginfo->prefix);
-#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
-	else if (par->family == NFPROTO_IPV6)
-		nf_log_ip6_packet(net, NFPROTO_IPV6, par->hooknum, skb, par->in,
-				  par->out, &li, loginfo->prefix);
-#endif
-	else
-		WARN_ON_ONCE(1);
-
+	nf_log_packet(net, par->family, par->hooknum, skb, par->in, par->out,
+		      &li, loginfo->prefix);
 	return XT_CONTINUE;
 }
 
@@ -70,7 +61,12 @@ static int log_tg_check(const struct xt_tgchk_param *par)
 		return -EINVAL;
 	}
 
-	return 0;
+	return nf_logger_find_get(par->family, NF_LOG_TYPE_LOG);
+}
+
+static void log_tg_destroy(const struct xt_tgdtor_param *par)
+{
+	nf_logger_put(par->family, NF_LOG_TYPE_LOG);
 }
 
 static struct xt_target log_tg_regs[] __read_mostly = {
@@ -80,6 +76,7 @@ static struct xt_target log_tg_regs[] __read_mostly = {
 		.target		= log_tg,
 		.targetsize	= sizeof(struct xt_log_info),
 		.checkentry	= log_tg_check,
+		.destroy	= log_tg_destroy,
 		.me		= THIS_MODULE,
 	},
 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
@@ -89,6 +86,7 @@ static struct xt_target log_tg_regs[] __read_mostly = {
 		.target		= log_tg,
 		.targetsize	= sizeof(struct xt_log_info),
 		.checkentry	= log_tg_check,
+		.destroy	= log_tg_destroy,
 		.me		= THIS_MODULE,
 	},
 #endif