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List: netfilter-devel
Subject: [PATCH 2/2][priv_data-condition] xt_condition
From: Massimiliano Hofer <max () nucleus ! it>
Date: 2006-09-24 22:42:10
Message-ID: 200609250042.10931.max () nucleus ! it
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From fad7ddb4c6c1daa2b2bbd88756a5f88824ff8bdb Mon Sep 17 00:00:00 2001
From: Massimiliano Hofer <max@nucleus.it>
Date: Mon, 25 Sep 2006 00:38:14 +0200
Subject: [PATCH] xt_condition
This patch implements the condition match.
It needs priv_data.
Signed-off-by: Massimiliano Hofer <max@nucleus.it>
---
include/linux/netfilter/xt_condition.h | 11 +
net/netfilter/Kconfig | 10 +
net/netfilter/Makefile | 1
net/netfilter/xt_condition.c | 292 ++++++++++++++++++++++++++++++++
4 files changed, 314 insertions(+), 0 deletions(-)
diff --git a/include/linux/netfilter/xt_condition.h b/include/linux/netfilter/xt_condition.h
new file mode 100644
index 0000000..f0706d0
--- /dev/null
+++ b/include/linux/netfilter/xt_condition.h
@@ -0,0 +1,11 @@
+#ifndef _XT_CONDITION_H
+#define _XT_CONDITION_H
+
+#define CONDITION_NAME_LEN 32
+
+struct condition_info {
+ char name[CONDITION_NAME_LEN];
+ int invert;
+};
+
+#endif /* _XT_CONDITION_H */
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 0a28d2c..4b6c9fc 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -228,6 +228,16 @@ config NETFILTER_XT_MATCH_COMMENT
If you want to compile it as a module, say M here and read
<file:Documentation/modules.txt>. If unsure, say `N'.
+config NETFILTER_XT_MATCH_CONDITION
+ tristate '"condition" match support'
+ depends on NETFILTER_XTABLES && PROC_FS
+ help
+ This option allows you to match firewall rules against condition
+ variables stored in the /proc/net/nf_condition directory.
+
+ If you want to compile it as a module, say M here and read
+ Documentation/modules.txt. If unsure, say `N'.
+
config NETFILTER_XT_MATCH_CONNBYTES
tristate '"connbytes" per-connection counter match support'
depends on NETFILTER_XTABLES
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index a74be49..1cbd4ac 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -56,3 +56,4 @@ obj-$(CONFIG_NETFILTER_XT_MATCH_STATISTI
obj-$(CONFIG_NETFILTER_XT_MATCH_STRING) += xt_string.o
obj-$(CONFIG_NETFILTER_XT_MATCH_TCPMSS) += xt_tcpmss.o
obj-$(CONFIG_NETFILTER_XT_MATCH_PHYSDEV) += xt_physdev.o
+obj-$(CONFIG_NETFILTER_XT_MATCH_LENGTH) += xt_condition.o
diff --git a/net/netfilter/xt_condition.c b/net/netfilter/xt_condition.c
new file mode 100644
index 0000000..ec508dd
--- /dev/null
+++ b/net/netfilter/xt_condition.c
@@ -0,0 +1,292 @@
+/*-------------------------------------------*\
+| Netfilter Condition Module |
+| |
+| Description: This module allows firewall |
+| rules to match using condition variables |
+| stored in /proc files. |
+| |
+| Author: Stephane Ouellette 2002-10-22 |
+| <ouellettes@videotron.ca> |
+| Massimiliano Hofer 2006-05-15 |
+| <max@nucleus.it> |
+| |
+| History: |
+| 2003-02-10 Second version with improved |
+| locking and simplified code. |
+| 2006-05-15 2.6.16 adaptations. |
+| Locking overhaul. |
+| Various bug fixes. |
+| |
+| This software is distributed under the |
+| terms of the GNU GPL. |
+\*-------------------------------------------*/
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/spinlock.h>
+#include <asm/semaphore.h>
+#include <linux/string.h>
+#include <linux/list.h>
+#include <asm/atomic.h>
+#include <asm/uaccess.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_condition.h>
+
+/* Defaults, these can be overridden on the module command-line. */
+static unsigned int condition_list_perms = 0600;
+static unsigned int condition_uid_perms = 0;
+static unsigned int condition_gid_perms = 0;
+
+MODULE_AUTHOR("Stephane Ouellette <ouellettes@videotron.ca> and Massimiliano Hofer <max@nucleus.it>");
+MODULE_DESCRIPTION("Allows rules to match against condition variables");
+MODULE_LICENSE("GPL");
+module_param(condition_list_perms, uint, 0600);
+MODULE_PARM_DESC(condition_list_perms,"permissions on /proc/net/nf_condition/* files");
+module_param(condition_uid_perms, uint, 0600);
+MODULE_PARM_DESC(condition_uid_perms,"user owner of /proc/net/nf_condition/* files");
+module_param(condition_gid_perms, uint, 0600);
+MODULE_PARM_DESC(condition_gid_perms,"group owner of /proc/net/nf_condition/* files");
+MODULE_ALIAS("ipt_condition");
+MODULE_ALIAS("ip6t_condition");
+
+static const char dir_name[]="nf_condition";
+
+struct condition_variable {
+ struct list_head list;
+ struct proc_dir_entry *status_proc;
+ unsigned int refcount;
+ int enabled; /* TRUE == 1, FALSE == 0 */
+};
+
+/* proc_lock is a user context only semaphore used for write access */
+/* to the conditions' list. */
+static DECLARE_MUTEX(proc_lock);
+
+static LIST_HEAD(conditions_list);
+static struct proc_dir_entry *proc_net_condition = NULL;
+
+static int
+xt_condition_read_info(char __user *buffer, char **start, off_t offset,
+ int length, int *eof, void *data)
+{
+ struct condition_variable *var =
+ (struct condition_variable *) data;
+
+ buffer[0] = (var->enabled) ? '1' : '0';
+ buffer[1] = '\n';
+ if (length>=2)
+ *eof = 1;
+
+ return 2;
+}
+
+
+static int
+xt_condition_write_info(struct file *file, const char __user *buffer,
+ unsigned long length, void *data)
+{
+ struct condition_variable *var =
+ (struct condition_variable *) data;
+ char newval;
+
+ if (length>0) {
+ if (get_user(newval, buffer))
+ return -EFAULT;
+ /* Match only on the first character */
+ switch (newval) {
+ case '0':
+ var->enabled = 0;
+ break;
+ case '1':
+ var->enabled = 1;
+ break;
+ }
+ }
+
+ return (int) length;
+}
+
+
+static int
+match(const struct sk_buff *skb, const struct net_device *in,
+ const struct net_device *out, const struct xt_match *match,
+ const void *matchinfo, int offset,
+ unsigned int protoff, int *hotdrop, void *priv_data)
+{
+ const struct condition_info *info =
+ (const struct condition_info *)matchinfo;
+ struct condition_variable *var=
+ *(struct condition_variable **)priv_data;
+
+ return var->enabled ^ info->invert;
+}
+
+
+static int
+init(const char *tablename, const void *ip,
+ const struct xt_match *match,
+ void *matchinfo,
+ unsigned int hook_mask, void *priv_data)
+{
+ static const char * const forbidden_names[]={ "", ".", ".." };
+ struct condition_info *info = (struct condition_info *) matchinfo;
+ struct list_head *pos;
+ struct condition_variable *var, *newvar;
+
+ int i;
+
+ /* We don't want a '/' in a proc file name. */
+ for (i=0; i < CONDITION_NAME_LEN && info->name[i] != '\0'; i++)
+ if (info->name[i] == '/')
+ return 0;
+ /* We can't handle file names longer than CONDITION_NAME_LEN and */
+ /* we want a NULL terminated string. */
+ if (i == CONDITION_NAME_LEN)
+ return 0;
+
+ /* We don't want certain reserved names. */
+ for (i=0; i < sizeof(forbidden_names)/sizeof(char *); i++)
+ if(strcmp(info->name, forbidden_names[i])==0)
+ return 0;
+
+ /* Let's acquire the lock, check for the condition and add it */
+ /* or increase the reference counter. */
+ if (down_interruptible(&proc_lock))
+ return -EINTR;
+
+ list_for_each(pos, &conditions_list) {
+ var = list_entry(pos, struct condition_variable, list);
+ if (strcmp(info->name, var->status_proc->name) == 0) {
+ var->refcount++;
+ up(&proc_lock);
+ *(struct condition_variable **)priv_data=var;
+ return 1;
+ }
+ }
+
+ /* At this point, we need to allocate a new condition variable. */
+ newvar = kmalloc(sizeof(struct condition_variable), GFP_KERNEL);
+
+ if (!newvar) {
+ up(&proc_lock);
+ return -ENOMEM;
+ }
+
+ /* Create the condition variable's proc file entry. */
+ newvar->status_proc = create_proc_entry(info->name, condition_list_perms, proc_net_condition);
+
+ if (!newvar->status_proc) {
+ kfree(newvar);
+ up(&proc_lock);
+ return -ENOMEM;
+ }
+
+ newvar->refcount = 1;
+ newvar->enabled = 0;
+ newvar->status_proc->owner = THIS_MODULE;
+ newvar->status_proc->data = newvar;
+ wmb();
+ newvar->status_proc->read_proc = xt_condition_read_info;
+ newvar->status_proc->write_proc = xt_condition_write_info;
+
+ list_add_rcu(&newvar->list, &conditions_list);
+
+ newvar->status_proc->uid = condition_uid_perms;
+ newvar->status_proc->gid = condition_gid_perms;
+
+ up(&proc_lock);
+
+ *(struct condition_variable **)priv_data=newvar;
+
+ return 1;
+}
+
+
+static void
+destroy(const struct xt_match *match, void *matchinfo, void *priv_data)
+{
+ struct condition_variable *var=
+ *(struct condition_variable **)priv_data;
+
+ BUG_ON(priv_data==NULL);
+ BUG_ON(var==NULL);
+
+ down(&proc_lock);
+
+ if (--var->refcount == 0) {
+ list_del_rcu(&var->list);
+ remove_proc_entry(var->status_proc->name, proc_net_condition);
+ up(&proc_lock);
+ /* synchronize_rcu() would be goog enough, but */
+ /* synchronize_net() guarantees that no packet will go */
+ /* out with the old rule after succesful removal. */
+ synchronize_net();
+ kfree(var);
+ return;
+ }
+
+ up(&proc_lock);
+}
+
+
+static struct xt_match condition_match = {
+ .name = "condition",
+ .family = AF_INET,
+ .matchsize = sizeof(struct condition_info),
+ .priv_size = sizeof(struct condition_variable *),
+ .match = match,
+ .init = init,
+ .destroy = destroy,
+ .me = THIS_MODULE
+};
+
+static struct xt_match condition6_match = {
+ .name = "condition",
+ .family = AF_INET6,
+ .matchsize = sizeof(struct condition_info),
+ .priv_size = sizeof(struct condition_variable *),
+ .match = match,
+ .init = init,
+ .destroy = destroy,
+ .me = THIS_MODULE
+};
+
+static int __init xt_condition_init(void)
+{
+ int errorcode;
+
+ proc_net_condition = proc_mkdir(dir_name, proc_net);
+ if (!proc_net_condition) {
+ remove_proc_entry(dir_name, proc_net);
+ return -EACCES;
+ }
+
+ errorcode = xt_register_match(&condition_match);
+ if (errorcode) {
+ xt_unregister_match(&condition_match);
+ remove_proc_entry(dir_name, proc_net);
+ return errorcode;
+ }
+
+ errorcode = xt_register_match(&condition6_match);
+ if (errorcode) {
+ xt_unregister_match(&condition6_match);
+ xt_unregister_match(&condition_match);
+ remove_proc_entry(dir_name, proc_net);
+ return errorcode;
+ }
+
+ return 0;
+}
+
+
+static void __exit xt_condition_fini(void)
+{
+ xt_unregister_match(&condition6_match);
+ xt_unregister_match(&condition_match);
+ remove_proc_entry(dir_name, proc_net);
+}
+
+module_init(xt_condition_init);
+module_exit(xt_condition_fini);
--
1.4.2
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