[NETFILTER]: x_tables: add TRACE target
The TRACE target can be used to follow IP and IPv6 packets through
the ruleset.
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Patrick NcHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 7962306..650ab52 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -204,6 +204,112 @@
return (struct ipt_entry *)(base + offset);
}
+/* All zeroes == unconditional rule. */
+static inline int
+unconditional(const struct ipt_ip *ip)
+{
+ unsigned int i;
+
+ for (i = 0; i < sizeof(*ip)/sizeof(__u32); i++)
+ if (((__u32 *)ip)[i])
+ return 0;
+
+ return 1;
+}
+
+#if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
+ defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
+static const char *hooknames[] = {
+ [NF_IP_PRE_ROUTING] = "PREROUTING",
+ [NF_IP_LOCAL_IN] = "INPUT",
+ [NF_IP_FORWARD] = "FORWARD",
+ [NF_IP_LOCAL_OUT] = "OUTPUT",
+ [NF_IP_POST_ROUTING] = "POSTROUTING",
+};
+
+enum nf_ip_trace_comments {
+ NF_IP_TRACE_COMMENT_RULE,
+ NF_IP_TRACE_COMMENT_RETURN,
+ NF_IP_TRACE_COMMENT_POLICY,
+};
+
+static const char *comments[] = {
+ [NF_IP_TRACE_COMMENT_RULE] = "rule",
+ [NF_IP_TRACE_COMMENT_RETURN] = "return",
+ [NF_IP_TRACE_COMMENT_POLICY] = "policy",
+};
+
+static struct nf_loginfo trace_loginfo = {
+ .type = NF_LOG_TYPE_LOG,
+ .u = {
+ .log = {
+ .level = 4,
+ .logflags = NF_LOG_MASK,
+ },
+ },
+};
+
+static inline int
+get_chainname_rulenum(struct ipt_entry *s, struct ipt_entry *e,
+ char *hookname, char **chainname,
+ char **comment, unsigned int *rulenum)
+{
+ struct ipt_standard_target *t = (void *)ipt_get_target(s);
+
+ if (strcmp(t->target.u.kernel.target->name, IPT_ERROR_TARGET) == 0) {
+ /* Head of user chain: ERROR target with chainname */
+ *chainname = t->target.data;
+ (*rulenum) = 0;
+ } else if (s == e) {
+ (*rulenum)++;
+
+ if (s->target_offset == sizeof(struct ipt_entry)
+ && strcmp(t->target.u.kernel.target->name,
+ IPT_STANDARD_TARGET) == 0
+ && t->verdict < 0
+ && unconditional(&s->ip)) {
+ /* Tail of chains: STANDARD target (return/policy) */
+ *comment = *chainname == hookname
+ ? (char *)comments[NF_IP_TRACE_COMMENT_POLICY]
+ : (char *)comments[NF_IP_TRACE_COMMENT_RETURN];
+ }
+ return 1;
+ } else
+ (*rulenum)++;
+
+ return 0;
+}
+
+static void trace_packet(struct sk_buff *skb,
+ unsigned int hook,
+ const struct net_device *in,
+ const struct net_device *out,
+ char *tablename,
+ struct xt_table_info *private,
+ struct ipt_entry *e)
+{
+ void *table_base;
+ struct ipt_entry *root;
+ char *hookname, *chainname, *comment;
+ unsigned int rulenum = 0;
+
+ table_base = (void *)private->entries[smp_processor_id()];
+ root = get_entry(table_base, private->hook_entry[hook]);
+
+ hookname = chainname = (char *)hooknames[hook];
+ comment = (char *)comments[NF_IP_TRACE_COMMENT_RULE];
+
+ IPT_ENTRY_ITERATE(root,
+ private->size - private->hook_entry[hook],
+ get_chainname_rulenum,
+ e, hookname, &chainname, &comment, &rulenum);
+
+ nf_log_packet(AF_INET, hook, skb, in, out, &trace_loginfo,
+ "TRACE: %s:%s:%s:%u ",
+ tablename, chainname, comment, rulenum);
+}
+#endif
+
/* Returns one of the generic firewall policies, like NF_ACCEPT. */
unsigned int
ipt_do_table(struct sk_buff **pskb,
@@ -261,6 +367,14 @@
t = ipt_get_target(e);
IP_NF_ASSERT(t->u.kernel.target);
+
+#if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
+ defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
+ /* The packet is traced: log it */
+ if (unlikely((*pskb)->nf_trace))
+ trace_packet(*pskb, hook, in, out,
+ table->name, private, e);
+#endif
/* Standard target? */
if (!t->u.kernel.target->target) {
int v;
@@ -341,19 +455,6 @@
#endif
}
-/* All zeroes == unconditional rule. */
-static inline int
-unconditional(const struct ipt_ip *ip)
-{
- unsigned int i;
-
- for (i = 0; i < sizeof(*ip)/sizeof(__u32); i++)
- if (((__u32 *)ip)[i])
- return 0;
-
- return 1;
-}
-
/* Figures out from what hook each rule can be called: returns 0 if
there are loops. Puts hook bitmask in comefrom. */
static int