[NETFILTER] x_tables: Abstraction layer for {ip,ip6,arp}_tables
This monster-patch tries to do the best job for unifying the data
structures and backend interfaces for the three evil clones ip_tables,
ip6_tables and arp_tables. In an ideal world we would never have
allowed this kind of copy+paste programming... but well, our world
isn't (yet?) ideal.
o introduce a new x_tables module
o {ip,arp,ip6}_tables depend on this x_tables module
o registration functions for tables, matches and targets are only
wrappers around x_tables provided functions
o all matches/targets that are used from ip_tables and ip6_tables
are now implemented as xt_FOOBAR.c files and provide module aliases
to ipt_FOOBAR and ip6t_FOOBAR
o header files for xt_matches are in include/linux/netfilter/,
include/linux/netfilter_{ipv4,ipv6} contains compatibility wrappers
around the xt_FOOBAR.h headers
Based on this patchset we're going to further unify the code,
gradually getting rid of all the layer 3 specific assumptions.
Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
new file mode 100644
index 0000000..d7817af
--- /dev/null
+++ b/net/netfilter/x_tables.c
@@ -0,0 +1,624 @@
+/*
+ * x_tables core - Backend for {ip,ip6,arp}_tables
+ *
+ * Copyright (C) 2006-2006 Harald Welte <laforge@netfilter.org>
+ *
+ * Based on existing ip_tables code which is
+ * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
+ * Copyright (C) 2000-2005 Netfilter Core Team <coreteam@netfilter.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/socket.h>
+#include <linux/net.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/string.h>
+#include <linux/vmalloc.h>
+
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter_arp.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
+MODULE_DESCRIPTION("[ip,ip6,arp]_tables backend module");
+
+#define SMP_ALIGN(x) (((x) + SMP_CACHE_BYTES-1) & ~(SMP_CACHE_BYTES-1))
+
+struct xt_af {
+ struct semaphore mutex;
+ struct list_head match;
+ struct list_head target;
+ struct list_head tables;
+};
+
+static struct xt_af *xt;
+
+#ifdef DEBUG_IP_FIREWALL_USER
+#define duprintf(format, args...) printk(format , ## args)
+#else
+#define duprintf(format, args...)
+#endif
+
+enum {
+ TABLE,
+ TARGET,
+ MATCH,
+};
+
+/* Registration hooks for targets. */
+int
+xt_register_target(int af, struct xt_target *target)
+{
+ int ret;
+
+ ret = down_interruptible(&xt[af].mutex);
+ if (ret != 0)
+ return ret;
+ list_add(&target->list, &xt[af].target);
+ up(&xt[af].mutex);
+ return ret;
+}
+EXPORT_SYMBOL(xt_register_target);
+
+void
+xt_unregister_target(int af, struct xt_target *target)
+{
+ down(&xt[af].mutex);
+ LIST_DELETE(&xt[af].target, target);
+ up(&xt[af].mutex);
+}
+EXPORT_SYMBOL(xt_unregister_target);
+
+int
+xt_register_match(int af, struct xt_match *match)
+{
+ int ret;
+
+ ret = down_interruptible(&xt[af].mutex);
+ if (ret != 0)
+ return ret;
+
+ list_add(&match->list, &xt[af].match);
+ up(&xt[af].mutex);
+
+ return ret;
+}
+EXPORT_SYMBOL(xt_register_match);
+
+void
+xt_unregister_match(int af, struct xt_match *match)
+{
+ down(&xt[af].mutex);
+ LIST_DELETE(&xt[af].match, match);
+ up(&xt[af].mutex);
+}
+EXPORT_SYMBOL(xt_unregister_match);
+
+
+/*
+ * These are weird, but module loading must not be done with mutex
+ * held (since they will register), and we have to have a single
+ * function to use try_then_request_module().
+ */
+
+/* Find match, grabs ref. Returns ERR_PTR() on error. */
+struct xt_match *xt_find_match(int af, const char *name, u8 revision)
+{
+ struct xt_match *m;
+ int err = 0;
+
+ if (down_interruptible(&xt[af].mutex) != 0)
+ return ERR_PTR(-EINTR);
+
+ list_for_each_entry(m, &xt[af].match, list) {
+ if (strcmp(m->name, name) == 0) {
+ if (m->revision == revision) {
+ if (try_module_get(m->me)) {
+ up(&xt[af].mutex);
+ return m;
+ }
+ } else
+ err = -EPROTOTYPE; /* Found something. */
+ }
+ }
+ up(&xt[af].mutex);
+ return ERR_PTR(err);
+}
+EXPORT_SYMBOL(xt_find_match);
+
+/* Find target, grabs ref. Returns ERR_PTR() on error. */
+struct xt_target *xt_find_target(int af, const char *name, u8 revision)
+{
+ struct xt_target *t;
+ int err = 0;
+
+ if (down_interruptible(&xt[af].mutex) != 0)
+ return ERR_PTR(-EINTR);
+
+ list_for_each_entry(t, &xt[af].target, list) {
+ if (strcmp(t->name, name) == 0) {
+ if (t->revision == revision) {
+ if (try_module_get(t->me)) {
+ up(&xt[af].mutex);
+ return t;
+ }
+ } else
+ err = -EPROTOTYPE; /* Found something. */
+ }
+ }
+ up(&xt[af].mutex);
+ return ERR_PTR(err);
+}
+EXPORT_SYMBOL(xt_find_target);
+
+static const char *xt_prefix[NPROTO] = {
+ [AF_INET] = "ipt_%s",
+ [AF_INET6] = "ip6t_%s",
+ [NF_ARP] = "arpt_%s",
+};
+
+struct xt_target *xt_request_find_target(int af, const char *name, u8 revision)
+{
+ struct xt_target *target;
+
+ target = try_then_request_module(xt_find_target(af, name, revision),
+ xt_prefix[af], name);
+ if (IS_ERR(target) || !target)
+ return NULL;
+ return target;
+}
+EXPORT_SYMBOL_GPL(xt_request_find_target);
+
+static int match_revfn(int af, const char *name, u8 revision, int *bestp)
+{
+ struct xt_match *m;
+ int have_rev = 0;
+
+ list_for_each_entry(m, &xt[af].match, list) {
+ if (strcmp(m->name, name) == 0) {
+ if (m->revision > *bestp)
+ *bestp = m->revision;
+ if (m->revision == revision)
+ have_rev = 1;
+ }
+ }
+ return have_rev;
+}
+
+static int target_revfn(int af, const char *name, u8 revision, int *bestp)
+{
+ struct xt_target *t;
+ int have_rev = 0;
+
+ list_for_each_entry(t, &xt[af].target, list) {
+ if (strcmp(t->name, name) == 0) {
+ if (t->revision > *bestp)
+ *bestp = t->revision;
+ if (t->revision == revision)
+ have_rev = 1;
+ }
+ }
+ return have_rev;
+}
+
+/* Returns true or false (if no such extension at all) */
+int xt_find_revision(int af, const char *name, u8 revision, int target,
+ int *err)
+{
+ int have_rev, best = -1;
+
+ if (down_interruptible(&xt[af].mutex) != 0) {
+ *err = -EINTR;
+ return 1;
+ }
+ if (target == 1)
+ have_rev = target_revfn(af, name, revision, &best);
+ else
+ have_rev = match_revfn(af, name, revision, &best);
+ up(&xt[af].mutex);
+
+ /* Nothing at all? Return 0 to try loading module. */
+ if (best == -1) {
+ *err = -ENOENT;
+ return 0;
+ }
+
+ *err = best;
+ if (!have_rev)
+ *err = -EPROTONOSUPPORT;
+ return 1;
+}
+EXPORT_SYMBOL_GPL(xt_find_revision);
+
+struct xt_table_info *xt_alloc_table_info(unsigned int size)
+{
+ struct xt_table_info *newinfo;
+ int cpu;
+
+ /* Pedantry: prevent them from hitting BUG() in vmalloc.c --RR */
+ if ((SMP_ALIGN(size) >> PAGE_SHIFT) + 2 > num_physpages)
+ return NULL;
+
+ newinfo = kzalloc(sizeof(struct xt_table_info), GFP_KERNEL);
+ if (!newinfo)
+ return NULL;
+
+ newinfo->size = size;
+
+ for_each_cpu(cpu) {
+ if (size <= PAGE_SIZE)
+ newinfo->entries[cpu] = kmalloc_node(size,
+ GFP_KERNEL,
+ cpu_to_node(cpu));
+ else
+ newinfo->entries[cpu] = vmalloc_node(size,
+ cpu_to_node(cpu));
+
+ if (newinfo->entries[cpu] == NULL) {
+ xt_free_table_info(newinfo);
+ return NULL;
+ }
+ }
+
+ return newinfo;
+}
+EXPORT_SYMBOL(xt_alloc_table_info);
+
+void xt_free_table_info(struct xt_table_info *info)
+{
+ int cpu;
+
+ for_each_cpu(cpu) {
+ if (info->size <= PAGE_SIZE)
+ kfree(info->entries[cpu]);
+ else
+ vfree(info->entries[cpu]);
+ }
+ kfree(info);
+}
+EXPORT_SYMBOL(xt_free_table_info);
+
+/* Find table by name, grabs mutex & ref. Returns ERR_PTR() on error. */
+struct xt_table *xt_find_table_lock(int af, const char *name)
+{
+ struct xt_table *t;
+
+ if (down_interruptible(&xt[af].mutex) != 0)
+ return ERR_PTR(-EINTR);
+
+ list_for_each_entry(t, &xt[af].tables, list)
+ if (strcmp(t->name, name) == 0 && try_module_get(t->me))
+ return t;
+ up(&xt[af].mutex);
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(xt_find_table_lock);
+
+void xt_table_unlock(struct xt_table *table)
+{
+ up(&xt[table->af].mutex);
+}
+EXPORT_SYMBOL_GPL(xt_table_unlock);
+
+
+struct xt_table_info *
+xt_replace_table(struct xt_table *table,
+ unsigned int num_counters,
+ struct xt_table_info *newinfo,
+ int *error)
+{
+ struct xt_table_info *oldinfo, *private;
+
+ /* Do the substitution. */
+ write_lock_bh(&table->lock);
+ private = table->private;
+ /* Check inside lock: is the old number correct? */
+ if (num_counters != private->number) {
+ duprintf("num_counters != table->private->number (%u/%u)\n",
+ num_counters, private->number);
+ write_unlock_bh(&table->lock);
+ *error = -EAGAIN;
+ return NULL;
+ }
+ oldinfo = private;
+ table->private = newinfo;
+ newinfo->initial_entries = oldinfo->initial_entries;
+ write_unlock_bh(&table->lock);
+
+ return oldinfo;
+}
+EXPORT_SYMBOL_GPL(xt_replace_table);
+
+int xt_register_table(struct xt_table *table,
+ struct xt_table_info *bootstrap,
+ struct xt_table_info *newinfo)
+{
+ int ret;
+ struct xt_table_info *private;
+
+ ret = down_interruptible(&xt[table->af].mutex);
+ if (ret != 0)
+ return ret;
+
+ /* Don't autoload: we'd eat our tail... */
+ if (list_named_find(&xt[table->af].tables, table->name)) {
+ ret = -EEXIST;
+ goto unlock;
+ }
+
+ /* Simplifies replace_table code. */
+ table->private = bootstrap;
+ if (!xt_replace_table(table, 0, newinfo, &ret))
+ goto unlock;
+
+ private = table->private;
+ duprintf("table->private->number = %u\n", private->number);
+
+ /* save number of initial entries */
+ private->initial_entries = private->number;
+
+ rwlock_init(&table->lock);
+ list_prepend(&xt[table->af].tables, table);
+
+ ret = 0;
+ unlock:
+ up(&xt[table->af].mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(xt_register_table);
+
+void *xt_unregister_table(struct xt_table *table)
+{
+ struct xt_table_info *private;
+
+ down(&xt[table->af].mutex);
+ private = table->private;
+ LIST_DELETE(&xt[table->af].tables, table);
+ up(&xt[table->af].mutex);
+
+ return private;
+}
+EXPORT_SYMBOL_GPL(xt_unregister_table);
+
+#ifdef CONFIG_PROC_FS
+static char *xt_proto_prefix[NPROTO] = {
+ [AF_INET] = "ip",
+ [AF_INET6] = "ip6",
+ [NF_ARP] = "arp",
+};
+
+static struct list_head *xt_get_idx(struct list_head *list, struct seq_file *seq, loff_t pos)
+{
+ struct list_head *head = list->next;
+
+ if (!head || list_empty(list))
+ return NULL;
+
+ while (pos && (head = head->next)) {
+ if (head == list)
+ return NULL;
+ pos--;
+ }
+ return pos ? NULL : head;
+}
+
+static struct list_head *type2list(u_int16_t af, u_int16_t type)
+{
+ struct list_head *list;
+
+ switch (type) {
+ case TARGET:
+ list = &xt[af].target;
+ break;
+ case MATCH:
+ list = &xt[af].match;
+ break;
+ case TABLE:
+ list = &xt[af].tables;
+ break;
+ default:
+ list = NULL;
+ break;
+ }
+
+ return list;
+}
+
+static void *xt_tgt_seq_start(struct seq_file *seq, loff_t *pos)
+{
+ struct proc_dir_entry *pde = (struct proc_dir_entry *) seq->private;
+ u_int16_t af = (unsigned long)pde->data & 0xffff;
+ u_int16_t type = (unsigned long)pde->data >> 16;
+ struct list_head *list;
+
+ if (af >= NPROTO)
+ return NULL;
+
+ list = type2list(af, type);
+ if (!list)
+ return NULL;
+
+ if (down_interruptible(&xt[af].mutex) != 0)
+ return NULL;
+
+ return xt_get_idx(list, seq, *pos);
+}
+
+static void *xt_tgt_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+ struct proc_dir_entry *pde = seq->private;
+ u_int16_t af = (unsigned long)pde->data & 0xffff;
+ u_int16_t type = (unsigned long)pde->data >> 16;
+ struct list_head *list;
+
+ if (af >= NPROTO)
+ return NULL;
+
+ list = type2list(af, type);
+ if (!list)
+ return NULL;
+
+ (*pos)++;
+ return xt_get_idx(list, seq, *pos);
+}
+
+static void xt_tgt_seq_stop(struct seq_file *seq, void *v)
+{
+ struct proc_dir_entry *pde = seq->private;
+ u_int16_t af = (unsigned long)pde->data & 0xffff;
+
+ up(&xt[af].mutex);
+}
+
+static int xt_name_seq_show(struct seq_file *seq, void *v)
+{
+ char *name = (char *)v + sizeof(struct list_head);
+
+ if (strlen(name))
+ return seq_printf(seq, "%s\n", name);
+ else
+ return 0;
+}
+
+static struct seq_operations xt_tgt_seq_ops = {
+ .start = xt_tgt_seq_start,
+ .next = xt_tgt_seq_next,
+ .stop = xt_tgt_seq_stop,
+ .show = xt_name_seq_show,
+};
+
+static int xt_tgt_open(struct inode *inode, struct file *file)
+{
+ int ret;
+
+ ret = seq_open(file, &xt_tgt_seq_ops);
+ if (!ret) {
+ struct seq_file *seq = file->private_data;
+ struct proc_dir_entry *pde = PDE(inode);
+
+ seq->private = pde;
+ }
+
+ return ret;
+}
+
+static struct file_operations xt_file_ops = {
+ .owner = THIS_MODULE,
+ .open = xt_tgt_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release,
+};
+
+#define FORMAT_TABLES "_tables_names"
+#define FORMAT_MATCHES "_tables_matches"
+#define FORMAT_TARGETS "_tables_targets"
+
+#endif /* CONFIG_PROC_FS */
+
+int xt_proto_init(int af)
+{
+#ifdef CONFIG_PROC_FS
+ char buf[XT_FUNCTION_MAXNAMELEN];
+ struct proc_dir_entry *proc;
+#endif
+
+ if (af >= NPROTO)
+ return -EINVAL;
+
+
+#ifdef CONFIG_PROC_FS
+ strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
+ strlcat(buf, FORMAT_TABLES, sizeof(buf));
+ proc = proc_net_fops_create(buf, 0440, &xt_file_ops);
+ if (!proc)
+ goto out;
+ proc->data = (void *) ((unsigned long) af | (TABLE << 16));
+
+
+ strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
+ strlcat(buf, FORMAT_MATCHES, sizeof(buf));
+ proc = proc_net_fops_create(buf, 0440, &xt_file_ops);
+ if (!proc)
+ goto out_remove_tables;
+ proc->data = (void *) ((unsigned long) af | (MATCH << 16));
+
+ strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
+ strlcat(buf, FORMAT_TARGETS, sizeof(buf));
+ proc = proc_net_fops_create(buf, 0440, &xt_file_ops);
+ if (!proc)
+ goto out_remove_matches;
+ proc->data = (void *) ((unsigned long) af | (TARGET << 16));
+#endif
+
+ return 0;
+
+#ifdef CONFIG_PROC_FS
+out_remove_matches:
+ strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
+ strlcat(buf, FORMAT_MATCHES, sizeof(buf));
+ proc_net_remove(buf);
+
+out_remove_tables:
+ strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
+ strlcat(buf, FORMAT_TABLES, sizeof(buf));
+ proc_net_remove(buf);
+out:
+ return -1;
+#endif
+}
+EXPORT_SYMBOL_GPL(xt_proto_init);
+
+void xt_proto_fini(int af)
+{
+#ifdef CONFIG_PROC_FS
+ char buf[XT_FUNCTION_MAXNAMELEN];
+
+ strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
+ strlcat(buf, FORMAT_TABLES, sizeof(buf));
+ proc_net_remove(buf);
+
+ strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
+ strlcat(buf, FORMAT_TARGETS, sizeof(buf));
+ proc_net_remove(buf);
+
+ strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
+ strlcat(buf, FORMAT_MATCHES, sizeof(buf));
+ proc_net_remove(buf);
+#endif /*CONFIG_PROC_FS*/
+}
+EXPORT_SYMBOL_GPL(xt_proto_fini);
+
+
+static int __init xt_init(void)
+{
+ int i;
+
+ xt = kmalloc(sizeof(struct xt_af) * NPROTO, GFP_KERNEL);
+ if (!xt)
+ return -ENOMEM;
+
+ for (i = 0; i < NPROTO; i++) {
+ init_MUTEX(&xt[i].mutex);
+ INIT_LIST_HEAD(&xt[i].target);
+ INIT_LIST_HEAD(&xt[i].match);
+ INIT_LIST_HEAD(&xt[i].tables);
+ }
+ return 0;
+}
+
+static void __exit xt_fini(void)
+{
+ kfree(xt);
+}
+
+module_init(xt_init);
+module_exit(xt_fini);
+
