netfilter: ctnetlink: add CTA_HELP_INFO attribute

This attribute can be used to modify and to dump the internal
protocol information.

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

1 files changed, 18 insertions, 5 deletions

diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 8be0ab9b475..ae156dff488 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -902,7 +902,8 @@ static const struct nla_policy help_nla_policy[CTA_HELP_MAX+1] = {
 };
 
 static inline int
-ctnetlink_parse_help(const struct nlattr *attr, char **helper_name)
+ctnetlink_parse_help(const struct nlattr *attr, char **helper_name,
+                     struct nlattr **helpinfo)
 {
         struct nlattr *tb[CTA_HELP_MAX+1];
 
@@ -913,6 +914,9 @@ ctnetlink_parse_help(const struct nlattr *attr, char **helper_name)
 
         *helper_name = nla_data(tb[CTA_HELP_NAME]);
 
+        if (tb[CTA_HELP_INFO])
+                *helpinfo = tb[CTA_HELP_INFO];
+
         return 0;
 }
 
@@ -1173,13 +1177,14 @@ ctnetlink_change_helper(struct nf_conn *ct, const struct nlattr * const cda[])
         struct nf_conntrack_helper *helper;
         struct nf_conn_help *help = nfct_help(ct);
         char *helpname = NULL;
+        struct nlattr *helpinfo = NULL;
         int err;
 
         /* don't change helper of sibling connections */
         if (ct->master)
                 return -EBUSY;
 
-        err = ctnetlink_parse_help(cda[CTA_HELP], &helpname);
+        err = ctnetlink_parse_help(cda[CTA_HELP], &helpname, &helpinfo);
         if (err < 0)
                 return err;
 
@@ -1214,8 +1219,12 @@ ctnetlink_change_helper(struct nf_conn *ct, const struct nlattr * const cda[])
         }
 
         if (help) {
-                if (help->helper == helper)
+                if (help->helper == helper) {
+                        /* update private helper data if allowed. */
+                        if (helper->from_nlattr && helpinfo)
+                                helper->from_nlattr(helpinfo, ct);
                         return 0;
+                }
                 if (help->helper)
                         return -EBUSY;
                 /* need to zero data of old helper */
@@ -1411,8 +1420,9 @@ ctnetlink_create_conntrack(struct net *net, u16 zone,
         rcu_read_lock();
         if (cda[CTA_HELP]) {
                 char *helpname = NULL;
- 
-                err = ctnetlink_parse_help(cda[CTA_HELP], &helpname);
+                struct nlattr *helpinfo = NULL;
+
+                err = ctnetlink_parse_help(cda[CTA_HELP], &helpname, &helpinfo);
                 if (err < 0)
                         goto err2;
 
@@ -1446,6 +1456,9 @@ ctnetlink_create_conntrack(struct net *net, u16 zone,
                                 err = -ENOMEM;
                                 goto err2;
                         }
+                        /* set private helper data if allowed. */
+                        if (helper->from_nlattr && helpinfo)
+                                helper->from_nlattr(helpinfo, ct);
 
                         /* not in hash table yet so not strictly necessary */
                         RCU_INIT_POINTER(help->helper, helper);