[NETFILTER]: nf_conntrack: automatic sysctl registation for conntrack protocols

Add helper functions for sysctl registration with optional instantiating
of common path elements (like net/netfilter) and use it for support for
automatic registation of conntrack protocol sysctls.

Signed-off-by: Patrick McHardy <kaber@trash.net>

diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h
index 6ab5e2d..f6f3fcb 100644 (file)
--- a/include/linux/netfilter.h
+++ b/include/linux/netfilter.h
@@ -117,6 +117,16 @@ void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);
 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 
+#ifdef CONFIG_SYSCTL
+/* Sysctl registration */
+struct ctl_table_header *nf_register_sysctl_table(struct ctl_table *path,
+                                                 struct ctl_table *table);
+void nf_unregister_sysctl_table(struct ctl_table_header *header,
+                               struct ctl_table *table);
+extern struct ctl_table nf_net_netfilter_sysctl_path[];
+extern struct ctl_table nf_net_ipv4_netfilter_sysctl_path[];
+#endif /* CONFIG_SYSCTL */
+
 extern struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS];
 
 /* those NF_LOG_* defines and struct nf_loginfo are legacy definitios that will

diff --git a/include/net/netfilter/nf_conntrack_l3proto.h b/include/net/netfilter/nf_conntrack_l3proto.h
index 6364df0..664ddcf 100644 (file)
--- a/include/net/netfilter/nf_conntrack_l3proto.h
+++ b/include/net/netfilter/nf_conntrack_l3proto.h
@@ -75,6 +75,12 @@ struct nf_conntrack_l3proto
        int (*nfattr_to_tuple)(struct nfattr *tb[],
                               struct nf_conntrack_tuple *t);
 
+#ifdef CONFIG_SYSCTL
+       struct ctl_table_header *ctl_table_header;
+       struct ctl_table        *ctl_table_path;
+       struct ctl_table        *ctl_table;
+#endif /* CONFIG_SYSCTL */
+
        /* Module (if any) which this is connected to. */
        struct module *me;
 };

diff --git a/include/net/netfilter/nf_conntrack_l4proto.h b/include/net/netfilter/nf_conntrack_l4proto.h
index c22804a..fe1e8fa 100644 (file)
--- a/include/net/netfilter/nf_conntrack_l4proto.h
+++ b/include/net/netfilter/nf_conntrack_l4proto.h
@@ -76,6 +76,12 @@ struct nf_conntrack_l4proto
        int (*nfattr_to_tuple)(struct nfattr *tb[],
                               struct nf_conntrack_tuple *t);
 
+#ifdef CONFIG_SYSCTL
+       struct ctl_table_header **ctl_table_header;
+       struct ctl_table        *ctl_table;
+       unsigned int            *ctl_table_users;
+#endif /* CONFIG_SYSCTL */
+
        /* Module (if any) which this is connected to. */
        struct module *me;
 };

diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 627105d..84d529d 100644 (file)
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -4,6 +4,7 @@ nf_conntrack-y  := nf_conntrack_core.o nf_conntrack_standalone.o nf_conntrack_exp
 nf_conntrack-$(CONFIG_NF_CONNTRACK_EVENTS) += nf_conntrack_ecache.o
 
 obj-$(CONFIG_NETFILTER) = netfilter.o
+obj-$(CONFIG_SYSCTL) += nf_sysctl.o
 
 obj-$(CONFIG_NETFILTER_NETLINK) += nfnetlink.o
 obj-$(CONFIG_NETFILTER_NETLINK_QUEUE) += nfnetlink_queue.o

diff --git a/net/netfilter/nf_conntrack_proto.c b/net/netfilter/nf_conntrack_proto.c
index a6a3b1d..941b5c3 100644 (file)
--- a/net/netfilter/nf_conntrack_proto.c
+++ b/net/netfilter/nf_conntrack_proto.c
@@ -12,6 +12,7 @@
 #include <linux/types.h>
 #include <linux/netfilter.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/skbuff.h>
 #include <linux/vmalloc.h>
 #include <linux/stddef.h>
@@ -30,6 +31,34 @@
 struct nf_conntrack_l4proto **nf_ct_protos[PF_MAX] __read_mostly;
 struct nf_conntrack_l3proto *nf_ct_l3protos[AF_MAX] __read_mostly;
 
+#ifdef CONFIG_SYSCTL
+static DEFINE_MUTEX(nf_ct_proto_sysctl_mutex);
+
+static int
+nf_ct_register_sysctl(struct ctl_table_header **header, struct ctl_table *path,
+                     struct ctl_table *table, unsigned int *users)
+{
+       if (*header == NULL) {
+               *header = nf_register_sysctl_table(path, table);
+               if (*header == NULL)
+                       return -ENOMEM;
+       }
+       if (users != NULL)
+               (*users)++;
+       return 0;
+}
+
+static void
+nf_ct_unregister_sysctl(struct ctl_table_header **header,
+                       struct ctl_table *table, unsigned int *users)
+{
+       if (users != NULL && --*users > 0)
+               return;
+       nf_unregister_sysctl_table(*header, table);
+       *header = NULL;
+}
+#endif
+
 struct nf_conntrack_l4proto *
 __nf_ct_l4proto_find(u_int16_t l3proto, u_int8_t l4proto)
 {
@@ -124,6 +153,33 @@ static int kill_l4proto(struct nf_conn *i, void *data)
                        l4proto->l3proto);
 }
 
+static int nf_ct_l3proto_register_sysctl(struct nf_conntrack_l3proto *l3proto)
+{
+       int err = 0;
+
+#ifdef CONFIG_SYSCTL
+       mutex_lock(&nf_ct_proto_sysctl_mutex);
+       if (l3proto->ctl_table != NULL) {
+               err = nf_ct_register_sysctl(&l3proto->ctl_table_header,
+                                           l3proto->ctl_table_path,
+                                           l3proto->ctl_table, NULL);
+       }
+       mutex_unlock(&nf_ct_proto_sysctl_mutex);
+#endif
+       return err;
+}
+
+static void nf_ct_l3proto_unregister_sysctl(struct nf_conntrack_l3proto *l3proto)
+{
+#ifdef CONFIG_SYSCTL
+       mutex_lock(&nf_ct_proto_sysctl_mutex);
+       if (l3proto->ctl_table_header != NULL)
+               nf_ct_unregister_sysctl(&l3proto->ctl_table_header,
+                                       l3proto->ctl_table, NULL);
+       mutex_unlock(&nf_ct_proto_sysctl_mutex);
+#endif
+}
+
 int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto)
 {
        int ret = 0;
@@ -139,6 +195,12 @@ int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto)
                goto out_unlock;
        }
        nf_ct_l3protos[proto->l3proto] = proto;
+       write_unlock_bh(&nf_conntrack_lock);
+
+       ret = nf_ct_l3proto_register_sysctl(proto);
+       if (ret < 0)
+               nf_conntrack_l3proto_unregister(proto);
+       return ret;
 
 out_unlock:
        write_unlock_bh(&nf_conntrack_lock);
@@ -165,6 +227,8 @@ int nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto)
        nf_ct_l3protos[proto->l3proto] = &nf_conntrack_l3proto_generic;
        write_unlock_bh(&nf_conntrack_lock);
 
+       nf_ct_l3proto_unregister_sysctl(proto);
+
        /* Somebody could be still looking at the proto in bh. */
        synchronize_net();
 
@@ -175,6 +239,36 @@ out:
        return ret;
 }
 
+static int nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto *l4proto)
+{
+       int err = 0;
+
+#ifdef CONFIG_SYSCTL
+       mutex_lock(&nf_ct_proto_sysctl_mutex);
+       if (l4proto->ctl_table != NULL) {
+               err = nf_ct_register_sysctl(l4proto->ctl_table_header,
+                                           nf_net_netfilter_sysctl_path,
+                                           l4proto->ctl_table,
+                                           l4proto->ctl_table_users);
+       }
+       mutex_unlock(&nf_ct_proto_sysctl_mutex);
+#endif
+       return err;
+}
+
+static void nf_ct_l4proto_unregister_sysctl(struct nf_conntrack_l4proto *l4proto)
+{
+#ifdef CONFIG_SYSCTL
+       mutex_lock(&nf_ct_proto_sysctl_mutex);
+       if (l4proto->ctl_table_header != NULL &&
+           *l4proto->ctl_table_header != NULL)
+               nf_ct_unregister_sysctl(l4proto->ctl_table_header,
+                                       l4proto->ctl_table,
+                                       l4proto->ctl_table_users);
+       mutex_unlock(&nf_ct_proto_sysctl_mutex);
+#endif
+}
+
 /* FIXME: Allow NULL functions and sub in pointers to generic for
    them. --RR */
 int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
@@ -230,6 +324,12 @@ retry:
        }
 
        nf_ct_protos[l4proto->l3proto][l4proto->l4proto] = l4proto;
+       write_unlock_bh(&nf_conntrack_lock);
+
+       ret = nf_ct_l4proto_register_sysctl(l4proto);
+       if (ret < 0)
+               nf_conntrack_l4proto_unregister(l4proto);
+       return ret;
 
 out_unlock:
        write_unlock_bh(&nf_conntrack_lock);
@@ -257,6 +357,8 @@ int nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
                = &nf_conntrack_l4proto_generic;
        write_unlock_bh(&nf_conntrack_lock);
 
+       nf_ct_l4proto_unregister_sysctl(l4proto);
+
        /* Somebody could be still looking at the proto in bh. */
        synchronize_net();
 

diff --git a/net/netfilter/nf_sysctl.c b/net/netfilter/nf_sysctl.c
new file mode 100644 (file)
index 0000000..06ddddb
--- /dev/null
+++ b/net/netfilter/nf_sysctl.c
@@ -0,0 +1,134 @@
+/* nf_sysctl.c netfilter sysctl registration/unregistation
+ *
+ * Copyright (c) 2006 Patrick McHardy <kaber@trash.net>
+ */
+#include <linux/module.h>
+#include <linux/sysctl.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+
+static void
+path_free(struct ctl_table *path, struct ctl_table *table)
+{
+       struct ctl_table *t, *next;
+
+       for (t = path; t != NULL && t != table; t = next) {
+               next = t->child;
+               kfree(t);
+       }
+}
+
+static struct ctl_table *
+path_dup(struct ctl_table *path, struct ctl_table *table)
+{
+       struct ctl_table *t, *last = NULL, *tmp;
+
+       for (t = path; t != NULL; t = t->child) {
+               /* twice the size since path elements are terminated by an
+                * empty element */
+               tmp = kmemdup(t, 2 * sizeof(*t), GFP_KERNEL);
+               if (tmp == NULL) {
+                       if (last != NULL)
+                               path_free(path, table);
+                       return NULL;
+               }
+
+               if (last != NULL)
+                       last->child = tmp;
+               else
+                       path = tmp;
+               last = tmp;
+       }
+
+       if (last != NULL)
+               last->child = table;
+       else
+               path = table;
+
+       return path;
+}
+
+struct ctl_table_header *
+nf_register_sysctl_table(struct ctl_table *path, struct ctl_table *table)
+{
+       struct ctl_table_header *header;
+
+       path = path_dup(path, table);
+       if (path == NULL)
+               return NULL;
+       header = register_sysctl_table(path, 0);
+       if (header == NULL)
+               path_free(path, table);
+       return header;
+}
+EXPORT_SYMBOL_GPL(nf_register_sysctl_table);
+
+void
+nf_unregister_sysctl_table(struct ctl_table_header *header,
+                          struct ctl_table *table)
+{
+       struct ctl_table *path = header->ctl_table;
+
+       unregister_sysctl_table(header);
+       path_free(path, table);
+}
+EXPORT_SYMBOL_GPL(nf_unregister_sysctl_table);
+
+/* net/netfilter */
+static struct ctl_table nf_net_netfilter_table[] = {
+       {
+               .ctl_name       = NET_NETFILTER,
+               .procname       = "netfilter",
+               .mode           = 0555,
+       },
+       {
+               .ctl_name       = 0
+       }
+};
+struct ctl_table nf_net_netfilter_sysctl_path[] = {
+       {
+               .ctl_name       = CTL_NET,
+               .procname       = "net",
+               .mode           = 0555,
+               .child          = nf_net_netfilter_table,
+       },
+       {
+               .ctl_name       = 0
+       }
+};
+EXPORT_SYMBOL_GPL(nf_net_netfilter_sysctl_path);
+
+/* net/ipv4/netfilter */
+static struct ctl_table nf_net_ipv4_netfilter_table[] = {
+       {
+               .ctl_name       = NET_IPV4_NETFILTER,
+               .procname       = "netfilter",
+               .mode           = 0555,
+       },
+       {
+               .ctl_name       = 0
+       }
+};
+static struct ctl_table nf_net_ipv4_table[] = {
+       {
+               .ctl_name       = NET_IPV4,
+               .procname       = "ipv4",
+               .mode           = 0555,
+               .child          = nf_net_ipv4_netfilter_table,
+       },
+       {
+               .ctl_name       = 0
+       }
+};
+struct ctl_table nf_net_ipv4_netfilter_sysctl_path[] = {
+       {
+               .ctl_name       = CTL_NET,
+               .procname       = "net",
+               .mode           = 0555,
+               .child          = nf_net_ipv4_table,
+       },
+       {
+               .ctl_name       = 0
+       }
+};
+EXPORT_SYMBOL_GPL(nf_net_ipv4_netfilter_sysctl_path);