netfilter: add API to manage NAT helpers.

The API allows a conntrack helper to indicate its corresponding
NAT helper which then can be loaded and reference counted.

Signed-off-by: Flavio Leitner <fbl@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/net/netfilter/nf_conntrack_helper.h b/include/net/netfilter/nf_conntrack_helper.h
index 28bd456..44b5a00 100644 (file)
--- a/include/net/netfilter/nf_conntrack_helper.h
+++ b/include/net/netfilter/nf_conntrack_helper.h
@@ -15,7 +15,8 @@
 #include <net/netfilter/nf_conntrack_extend.h>
 #include <net/netfilter/nf_conntrack_expect.h>
 
-#define NF_NAT_HELPER_NAME(name)       "ip_nat_" name
+#define NF_NAT_HELPER_PREFIX           "ip_nat_"
+#define NF_NAT_HELPER_NAME(name)       NF_NAT_HELPER_PREFIX name
 #define MODULE_ALIAS_NF_NAT_HELPER(name) \
        MODULE_ALIAS(NF_NAT_HELPER_NAME(name))
 
@@ -58,6 +59,8 @@ struct nf_conntrack_helper {
        unsigned int queue_num;
        /* length of userspace private data stored in nf_conn_help->data */
        u16 data_len;
+       /* name of NAT helper module */
+       char nat_mod_name[NF_CT_HELPER_NAME_LEN];
 };
 
 /* Must be kept in sync with the classes defined by helpers */
@@ -157,4 +160,21 @@ nf_ct_helper_expectfn_find_by_symbol(const void *symbol);
 extern struct hlist_head *nf_ct_helper_hash;
 extern unsigned int nf_ct_helper_hsize;
 
+struct nf_conntrack_nat_helper {
+       struct list_head list;
+       char mod_name[NF_CT_HELPER_NAME_LEN];   /* module name */
+       struct module *module;                  /* pointer to self */
+};
+
+#define NF_CT_NAT_HELPER_INIT(name) \
+       { \
+       .mod_name = NF_NAT_HELPER_NAME(name), \
+       .module = THIS_MODULE \
+       }
+
+void nf_nat_helper_register(struct nf_conntrack_nat_helper *nat);
+void nf_nat_helper_unregister(struct nf_conntrack_nat_helper *nat);
+int nf_nat_helper_try_module_get(const char *name, u16 l3num,
+                                u8 protonum);
+void nf_nat_helper_put(struct nf_conntrack_helper *helper);
 #endif /*_NF_CONNTRACK_HELPER_H*/

diff --git a/net/netfilter/nf_conntrack_amanda.c b/net/netfilter/nf_conntrack_amanda.c
index f2681ec..dbec6fc 100644 (file)
--- a/net/netfilter/nf_conntrack_amanda.c
+++ b/net/netfilter/nf_conntrack_amanda.c
@@ -28,11 +28,13 @@
 static unsigned int master_timeout __read_mostly = 300;
 static char *ts_algo = "kmp";
 
+#define HELPER_NAME "amanda"
+
 MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>");
 MODULE_DESCRIPTION("Amanda connection tracking module");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("ip_conntrack_amanda");
-MODULE_ALIAS_NFCT_HELPER("amanda");
+MODULE_ALIAS_NFCT_HELPER(HELPER_NAME);
 
 module_param(master_timeout, uint, 0600);
 MODULE_PARM_DESC(master_timeout, "timeout for the master connection");
@@ -179,13 +181,14 @@ static const struct nf_conntrack_expect_policy amanda_exp_policy = {
 
 static struct nf_conntrack_helper amanda_helper[2] __read_mostly = {
        {
-               .name                   = "amanda",
+               .name                   = HELPER_NAME,
                .me                     = THIS_MODULE,
                .help                   = amanda_help,
                .tuple.src.l3num        = AF_INET,
                .tuple.src.u.udp.port   = cpu_to_be16(10080),
                .tuple.dst.protonum     = IPPROTO_UDP,
                .expect_policy          = &amanda_exp_policy,
+               .nat_mod_name           = NF_NAT_HELPER_NAME(HELPER_NAME),
        },
        {
                .name                   = "amanda",
@@ -195,6 +198,7 @@ static struct nf_conntrack_helper amanda_helper[2] __read_mostly = {
                .tuple.src.u.udp.port   = cpu_to_be16(10080),
                .tuple.dst.protonum     = IPPROTO_UDP,
                .expect_policy          = &amanda_exp_policy,
+               .nat_mod_name           = NF_NAT_HELPER_NAME(HELPER_NAME),
        },
 };
 

diff --git a/net/netfilter/nf_conntrack_ftp.c b/net/netfilter/nf_conntrack_ftp.c
index a11c304..32aeac1 100644 (file)
--- a/net/netfilter/nf_conntrack_ftp.c
+++ b/net/netfilter/nf_conntrack_ftp.c
@@ -29,11 +29,13 @@
 #include <net/netfilter/nf_conntrack_helper.h>
 #include <linux/netfilter/nf_conntrack_ftp.h>
 
+#define HELPER_NAME "ftp"
+
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
 MODULE_DESCRIPTION("ftp connection tracking helper");
 MODULE_ALIAS("ip_conntrack_ftp");
-MODULE_ALIAS_NFCT_HELPER("ftp");
+MODULE_ALIAS_NFCT_HELPER(HELPER_NAME);
 
 /* This is slow, but it's simple. --RR */
 static char *ftp_buffer;
@@ -588,12 +590,14 @@ static int __init nf_conntrack_ftp_init(void)
        /* FIXME should be configurable whether IPv4 and IPv6 FTP connections
                 are tracked or not - YK */
        for (i = 0; i < ports_c; i++) {
-               nf_ct_helper_init(&ftp[2 * i], AF_INET, IPPROTO_TCP, "ftp",
-                                 FTP_PORT, ports[i], ports[i], &ftp_exp_policy,
-                                 0, help, nf_ct_ftp_from_nlattr, THIS_MODULE);
-               nf_ct_helper_init(&ftp[2 * i + 1], AF_INET6, IPPROTO_TCP, "ftp",
-                                 FTP_PORT, ports[i], ports[i], &ftp_exp_policy,
-                                 0, help, nf_ct_ftp_from_nlattr, THIS_MODULE);
+               nf_ct_helper_init(&ftp[2 * i], AF_INET, IPPROTO_TCP,
+                                 HELPER_NAME, FTP_PORT, ports[i], ports[i],
+                                 &ftp_exp_policy, 0, help,
+                                 nf_ct_ftp_from_nlattr, THIS_MODULE);
+               nf_ct_helper_init(&ftp[2 * i + 1], AF_INET6, IPPROTO_TCP,
+                                 HELPER_NAME, FTP_PORT, ports[i], ports[i],
+                                 &ftp_exp_policy, 0, help,
+                                 nf_ct_ftp_from_nlattr, THIS_MODULE);
        }
 
        ret = nf_conntrack_helpers_register(ftp, ports_c * 2);

diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
index 274baf1..918df7f 100644 (file)
--- a/net/netfilter/nf_conntrack_helper.c
+++ b/net/netfilter/nf_conntrack_helper.c
@@ -42,6 +42,9 @@ module_param_named(nf_conntrack_helper, nf_ct_auto_assign_helper, bool, 0644);
 MODULE_PARM_DESC(nf_conntrack_helper,
                 "Enable automatic conntrack helper assignment (default 0)");
 
+static DEFINE_MUTEX(nf_ct_nat_helpers_mutex);
+static struct list_head nf_ct_nat_helpers __read_mostly;
+
 /* Stupid hash, but collision free for the default registrations of the
  * helpers currently in the kernel. */
 static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
@@ -130,6 +133,70 @@ void nf_conntrack_helper_put(struct nf_conntrack_helper *helper)
 }
 EXPORT_SYMBOL_GPL(nf_conntrack_helper_put);
 
+static struct nf_conntrack_nat_helper *
+nf_conntrack_nat_helper_find(const char *mod_name)
+{
+       struct nf_conntrack_nat_helper *cur;
+       bool found = false;
+
+       list_for_each_entry_rcu(cur, &nf_ct_nat_helpers, list) {
+               if (!strcmp(cur->mod_name, mod_name)) {
+                       found = true;
+                       break;
+               }
+       }
+       return found ? cur : NULL;
+}
+
+int
+nf_nat_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
+{
+       struct nf_conntrack_helper *h;
+       struct nf_conntrack_nat_helper *nat;
+       char mod_name[NF_CT_HELPER_NAME_LEN];
+       int ret = 0;
+
+       rcu_read_lock();
+       h = __nf_conntrack_helper_find(name, l3num, protonum);
+       if (!h) {
+               rcu_read_unlock();
+               return -ENOENT;
+       }
+
+       nat = nf_conntrack_nat_helper_find(h->nat_mod_name);
+       if (!nat) {
+               snprintf(mod_name, sizeof(mod_name), "%s", h->nat_mod_name);
+               rcu_read_unlock();
+               request_module(mod_name);
+
+               rcu_read_lock();
+               nat = nf_conntrack_nat_helper_find(mod_name);
+               if (!nat) {
+                       rcu_read_unlock();
+                       return -ENOENT;
+               }
+       }
+
+       if (!try_module_get(nat->module))
+               ret = -ENOENT;
+
+       rcu_read_unlock();
+       return ret;
+}
+EXPORT_SYMBOL_GPL(nf_nat_helper_try_module_get);
+
+void nf_nat_helper_put(struct nf_conntrack_helper *helper)
+{
+       struct nf_conntrack_nat_helper *nat;
+
+       nat = nf_conntrack_nat_helper_find(helper->nat_mod_name);
+       if (WARN_ON_ONCE(!nat))
+               return;
+
+       module_put(nat->module);
+}
+EXPORT_SYMBOL_GPL(nf_nat_helper_put);
+
 struct nf_conn_help *
 nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp)
 {
@@ -430,6 +497,8 @@ void nf_ct_helper_init(struct nf_conntrack_helper *helper,
        helper->help = help;
        helper->from_nlattr = from_nlattr;
        helper->me = module;
+       snprintf(helper->nat_mod_name, sizeof(helper->nat_mod_name),
+                NF_NAT_HELPER_PREFIX "%s", name);
 
        if (spec_port == default_port)
                snprintf(helper->name, sizeof(helper->name), "%s", name);
@@ -466,6 +535,22 @@ void nf_conntrack_helpers_unregister(struct nf_conntrack_helper *helper,
 }
 EXPORT_SYMBOL_GPL(nf_conntrack_helpers_unregister);
 
+void nf_nat_helper_register(struct nf_conntrack_nat_helper *nat)
+{
+       mutex_lock(&nf_ct_nat_helpers_mutex);
+       list_add_rcu(&nat->list, &nf_ct_nat_helpers);
+       mutex_unlock(&nf_ct_nat_helpers_mutex);
+}
+EXPORT_SYMBOL_GPL(nf_nat_helper_register);
+
+void nf_nat_helper_unregister(struct nf_conntrack_nat_helper *nat)
+{
+       mutex_lock(&nf_ct_nat_helpers_mutex);
+       list_del_rcu(&nat->list);
+       mutex_unlock(&nf_ct_nat_helpers_mutex);
+}
+EXPORT_SYMBOL_GPL(nf_nat_helper_unregister);
+
 static const struct nf_ct_ext_type helper_extend = {
        .len    = sizeof(struct nf_conn_help),
        .align  = __alignof__(struct nf_conn_help),
@@ -493,6 +578,7 @@ int nf_conntrack_helper_init(void)
                goto out_extend;
        }
 
+       INIT_LIST_HEAD(&nf_ct_nat_helpers);
        return 0;
 out_extend:
        kvfree(nf_ct_helper_hash);

diff --git a/net/netfilter/nf_conntrack_irc.c b/net/netfilter/nf_conntrack_irc.c
index 4099f4d..79e5014 100644 (file)
--- a/net/netfilter/nf_conntrack_irc.c
+++ b/net/netfilter/nf_conntrack_irc.c
@@ -42,11 +42,13 @@ unsigned int (*nf_nat_irc_hook)(struct sk_buff *skb,
                                struct nf_conntrack_expect *exp) __read_mostly;
 EXPORT_SYMBOL_GPL(nf_nat_irc_hook);
 
+#define HELPER_NAME "irc"
+
 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
 MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("ip_conntrack_irc");
-MODULE_ALIAS_NFCT_HELPER("irc");
+MODULE_ALIAS_NFCT_HELPER(HELPER_NAME);
 
 module_param_array(ports, ushort, &ports_c, 0400);
 MODULE_PARM_DESC(ports, "port numbers of IRC servers");
@@ -259,7 +261,7 @@ static int __init nf_conntrack_irc_init(void)
                ports[ports_c++] = IRC_PORT;
 
        for (i = 0; i < ports_c; i++) {
-               nf_ct_helper_init(&irc[i], AF_INET, IPPROTO_TCP, "irc",
+               nf_ct_helper_init(&irc[i], AF_INET, IPPROTO_TCP, HELPER_NAME,
                                  IRC_PORT, ports[i], i, &irc_exp_policy,
                                  0, help, NULL, THIS_MODULE);
        }

diff --git a/net/netfilter/nf_conntrack_sane.c b/net/netfilter/nf_conntrack_sane.c
index 5072ff9..8330664 100644 (file)
--- a/net/netfilter/nf_conntrack_sane.c
+++ b/net/netfilter/nf_conntrack_sane.c
@@ -30,10 +30,12 @@
 #include <net/netfilter/nf_conntrack_expect.h>
 #include <linux/netfilter/nf_conntrack_sane.h>
 
+#define HELPER_NAME "sane"
+
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Michal Schmidt <mschmidt@redhat.com>");
 MODULE_DESCRIPTION("SANE connection tracking helper");
-MODULE_ALIAS_NFCT_HELPER("sane");
+MODULE_ALIAS_NFCT_HELPER(HELPER_NAME);
 
 static char *sane_buffer;
 
@@ -195,12 +197,12 @@ static int __init nf_conntrack_sane_init(void)
        /* FIXME should be configurable whether IPv4 and IPv6 connections
                 are tracked or not - YK */
        for (i = 0; i < ports_c; i++) {
-               nf_ct_helper_init(&sane[2 * i], AF_INET, IPPROTO_TCP, "sane",
-                                 SANE_PORT, ports[i], ports[i],
+               nf_ct_helper_init(&sane[2 * i], AF_INET, IPPROTO_TCP,
+                                 HELPER_NAME, SANE_PORT, ports[i], ports[i],
                                  &sane_exp_policy, 0, help, NULL,
                                  THIS_MODULE);
-               nf_ct_helper_init(&sane[2 * i + 1], AF_INET6, IPPROTO_TCP, "sane",
-                                 SANE_PORT, ports[i], ports[i],
+               nf_ct_helper_init(&sane[2 * i + 1], AF_INET6, IPPROTO_TCP,
+                                 HELPER_NAME, SANE_PORT, ports[i], ports[i],
                                  &sane_exp_policy, 0, help, NULL,
                                  THIS_MODULE);
        }

diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
index d5454d1..c30c883 100644 (file)
--- a/net/netfilter/nf_conntrack_sip.c
+++ b/net/netfilter/nf_conntrack_sip.c
@@ -30,11 +30,13 @@
 #include <net/netfilter/nf_conntrack_zones.h>
 #include <linux/netfilter/nf_conntrack_sip.h>
 
+#define HELPER_NAME "sip"
+
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>");
 MODULE_DESCRIPTION("SIP connection tracking helper");
 MODULE_ALIAS("ip_conntrack_sip");
-MODULE_ALIAS_NFCT_HELPER("sip");
+MODULE_ALIAS_NFCT_HELPER(HELPER_NAME);
 
 #define MAX_PORTS      8
 static unsigned short ports[MAX_PORTS];
@@ -1669,21 +1671,21 @@ static int __init nf_conntrack_sip_init(void)
                ports[ports_c++] = SIP_PORT;
 
        for (i = 0; i < ports_c; i++) {
-               nf_ct_helper_init(&sip[4 * i], AF_INET, IPPROTO_UDP, "sip",
-                                 SIP_PORT, ports[i], i, sip_exp_policy,
-                                 SIP_EXPECT_MAX, sip_help_udp,
+               nf_ct_helper_init(&sip[4 * i], AF_INET, IPPROTO_UDP,
+                                 HELPER_NAME, SIP_PORT, ports[i], i,
+                                 sip_exp_policy, SIP_EXPECT_MAX, sip_help_udp,
                                  NULL, THIS_MODULE);
-               nf_ct_helper_init(&sip[4 * i + 1], AF_INET, IPPROTO_TCP, "sip",
-                                 SIP_PORT, ports[i], i, sip_exp_policy,
-                                 SIP_EXPECT_MAX, sip_help_tcp,
+               nf_ct_helper_init(&sip[4 * i + 1], AF_INET, IPPROTO_TCP,
+                                 HELPER_NAME, SIP_PORT, ports[i], i,
+                                 sip_exp_policy, SIP_EXPECT_MAX, sip_help_tcp,
                                  NULL, THIS_MODULE);
-               nf_ct_helper_init(&sip[4 * i + 2], AF_INET6, IPPROTO_UDP, "sip",
-                                 SIP_PORT, ports[i], i, sip_exp_policy,
-                                 SIP_EXPECT_MAX, sip_help_udp,
+               nf_ct_helper_init(&sip[4 * i + 2], AF_INET6, IPPROTO_UDP,
+                                 HELPER_NAME, SIP_PORT, ports[i], i,
+                                 sip_exp_policy, SIP_EXPECT_MAX, sip_help_udp,
                                  NULL, THIS_MODULE);
-               nf_ct_helper_init(&sip[4 * i + 3], AF_INET6, IPPROTO_TCP, "sip",
-                                 SIP_PORT, ports[i], i, sip_exp_policy,
-                                 SIP_EXPECT_MAX, sip_help_tcp,
+               nf_ct_helper_init(&sip[4 * i + 3], AF_INET6, IPPROTO_TCP,
+                                 HELPER_NAME, SIP_PORT, ports[i], i,
+                                 sip_exp_policy, SIP_EXPECT_MAX, sip_help_tcp,
                                  NULL, THIS_MODULE);
        }
 

diff --git a/net/netfilter/nf_conntrack_tftp.c b/net/netfilter/nf_conntrack_tftp.c
index 548b673..6977cb9 100644 (file)
--- a/net/netfilter/nf_conntrack_tftp.c
+++ b/net/netfilter/nf_conntrack_tftp.c
@@ -20,11 +20,13 @@
 #include <net/netfilter/nf_conntrack_helper.h>
 #include <linux/netfilter/nf_conntrack_tftp.h>
 
+#define HELPER_NAME "tftp"
+
 MODULE_AUTHOR("Magnus Boden <mb@ozaba.mine.nu>");
 MODULE_DESCRIPTION("TFTP connection tracking helper");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("ip_conntrack_tftp");
-MODULE_ALIAS_NFCT_HELPER("tftp");
+MODULE_ALIAS_NFCT_HELPER(HELPER_NAME);
 
 #define MAX_PORTS 8
 static unsigned short ports[MAX_PORTS];
@@ -119,12 +121,14 @@ static int __init nf_conntrack_tftp_init(void)
                ports[ports_c++] = TFTP_PORT;
 
        for (i = 0; i < ports_c; i++) {
-               nf_ct_helper_init(&tftp[2 * i], AF_INET, IPPROTO_UDP, "tftp",
-                                 TFTP_PORT, ports[i], i, &tftp_exp_policy,
-                                 0, tftp_help, NULL, THIS_MODULE);
-               nf_ct_helper_init(&tftp[2 * i + 1], AF_INET6, IPPROTO_UDP, "tftp",
-                                 TFTP_PORT, ports[i], i, &tftp_exp_policy,
-                                 0, tftp_help, NULL, THIS_MODULE);
+               nf_ct_helper_init(&tftp[2 * i], AF_INET, IPPROTO_UDP,
+                                 HELPER_NAME, TFTP_PORT, ports[i], i,
+                                 &tftp_exp_policy, 0, tftp_help, NULL,
+                                 THIS_MODULE);
+               nf_ct_helper_init(&tftp[2 * i + 1], AF_INET6, IPPROTO_UDP,
+                                 HELPER_NAME, TFTP_PORT, ports[i], i,
+                                 &tftp_exp_policy, 0, tftp_help, NULL,
+                                 THIS_MODULE);
        }
 
        ret = nf_conntrack_helpers_register(tftp, ports_c * 2);