condition: import 20080125 code base

extensions/Kbuild

@@ -11,6 +11,7 @@ obj-${build_ECHO}    += xt_ECHO.o
 obj-${build_LOGMARK} += xt_LOGMARK.o
 obj-${build_TARPIT}  += xt_TARPIT.o
 obj-${build_TEE}     += xt_TEE.o
+obj-${build_condition} += xt_condition.o
 obj-${build_geoip}    += xt_geoip.o
 obj-${build_portscan} += xt_portscan.o
 

extensions/Mbuild

@@ -4,5 +4,6 @@ obj-${build_ECHO}     += libxt_ECHO.so
 obj-${build_LOGMARK}  += libxt_LOGMARK.so
 obj-${build_TARPIT}   += libxt_TARPIT.so
 obj-${build_TEE}      += libxt_TEE.so
+obj-${build_condition} += libxt_condition.so
 obj-${build_geoip}    += libxt_geoip.so
 obj-${build_portscan} += libxt_portscan.so

extensions/libxt_condition.c

@@ -0,0 +1,90 @@
+/* Shared library add-on to iptables for condition match */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <getopt.h>
+#include <xtables.h>
+#include "xt_condition.h"
+
+static void condition_help(void)
+{
+	printf("condition match options:\n"
+	       "--condition [!] filename       "
+	       "Match on boolean value stored in /proc file\n");
+}
+
+static const struct option condition_opts[] = {
+	{ .name = "condition", .has_arg = 1, .flag = 0, .val = 'X' },
+	{ .name = 0 }
+};
+
+static int condition_parse(int c, char **argv, int invert, unsigned int *flags,
+                           const void *entry, struct xt_entry_match **match)
+{
+	struct condition_info *info =
+	    (struct condition_info *) (*match)->data;
+
+	if (c == 'X') {
+		if (*flags)
+			exit_error(PARAMETER_PROBLEM,
+				   "Can't specify multiple conditions");
+
+		check_inverse(optarg, &invert, &optind, 0);
+
+		if (strlen(argv[optind - 1]) < CONDITION_NAME_LEN)
+			strcpy(info->name, argv[optind - 1]);
+		else
+			exit_error(PARAMETER_PROBLEM,
+				   "File name too long");
+
+		info->invert = invert;
+		*flags = 1;
+		return 1;
+	}
+
+	return 0;
+}
+
+static void condition_check(unsigned int flags)
+{
+	if (!flags)
+		exit_error(PARAMETER_PROBLEM,
+			   "Condition match: must specify --condition");
+}
+
+static void condition_print(const void *ip, const struct xt_entry_match *match,
+                            int numeric)
+{
+	const struct condition_info *info =
+	    (const struct condition_info *) match->data;
+
+	printf("condition %s%s ", (info->invert) ? "!" : "", info->name);
+}
+
+
+static void condition_save(const void *ip, const struct xt_entry_match *match)
+{
+	const struct condition_info *info =
+	    (const struct condition_info *) match->data;
+
+	printf("--condition %s\"%s\" ", (info->invert) ? "! " : "", info->name);
+}
+
+static struct xtables_match condition_match = {
+	.name 		= "condition",
+	.version 	= XTABLES_VERSION,
+	.size 		= XT_ALIGN(sizeof(struct condition_info)),
+	.userspacesize 	= XT_ALIGN(sizeof(struct condition_info)),
+	.help 		= condition_help,
+	.parse 		= condition_parse,
+	.final_check	= condition_check,
+	.print 		= condition_print,
+	.save 		= condition_save,
+	.extra_opts 	= condition_opts,
+};
+
+void _init(void);
+void _init(void)
+{
+	xtables_register_match(&condition_match);
+}

extensions/libxt_condition.man

@@ -0,0 +1,4 @@
+This matches if a specific /proc filename is '0' or '1'.
+.TP
+.BI "--condition " "[!] \fIfilename\fP"
+Match on boolean value stored in /proc/net/ipt_condition/filename file

extensions/xt_condition.Kconfig

@@ -0,0 +1,6 @@
+config NETFILTER_XT_MATCH_CONDITION
+	tristate '"condition" match support'
+	depends on NETFILTER_XTABLES && NETFILTER_ADVANCED
+	---help---
+	This option allows you to match firewall rules against condition
+	variables stored in the /proc/net/nf_condition directory.

extensions/xt_condition.c

@@ -0,0 +1,345 @@
+/*-------------------------------------------*\
+|          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/version.h>
+#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 "xt_condition.h"
+#include "compat_xtables.h"
+
+#ifndef CONFIG_PROC_FS
+#error  "Proc file system support is required for this module"
+#endif
+
+/* Defaults, these can be overridden on the module command-line. */
+static unsigned int condition_list_perms = 0644;
+static unsigned int compat_dir_name = 0;
+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_param(compat_dir_name, bool, 0400);
+MODULE_PARM_DESC(compat_dir_name,"use old style /proc/net/ipt_condition/* files");
+MODULE_ALIAS("ipt_condition");
+MODULE_ALIAS("ip6t_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 const char *dir_name;
+
+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) != 0)
+			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;
+}
+
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,24)
+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)
+#else
+bool
+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, bool *hotdrop)
+#endif
+{
+	const struct condition_info *info =
+	    (const struct condition_info *) matchinfo;
+	struct condition_variable *var;
+	int condition_status = 0;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(var, &conditions_list, list) {
+		if (strcmp(info->name, var->status_proc->name) == 0) {
+			condition_status = var->enabled;
+			break;
+		}
+	}
+	rcu_read_unlock();
+
+	return condition_status ^ info->invert;
+}
+
+
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,24)
+static int
+#else
+bool
+#endif
+checkentry(const char *tablename, const void *ip,
+	   const struct xt_match *match,
+	   void *matchinfo,
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,19)
+	   unsigned int matchsize,
+#endif
+	   unsigned int hook_mask)
+{
+	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);
+			return 1;
+		}
+	}
+
+	/* At this point, we need to allocate a new condition variable. */
+	newvar = kmalloc(sizeof(struct condition_variable), GFP_KERNEL);
+
+	if (newvar == NULL) {
+		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 == NULL) {
+		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);
+
+	return 1;
+}
+
+
+static void
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,19)
+destroy(const struct xt_match *match, void *matchinfo,
+	unsigned int matchsize)
+#else
+destroy(const struct xt_match *match, void *matchinfo)
+#endif
+{
+	struct condition_info *info = (struct condition_info *) matchinfo;
+	struct list_head *pos;
+	struct condition_variable *var;
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,19)
+	if (matchsize != XT_ALIGN(sizeof(struct condition_info)))
+		return;
+#endif
+
+	down(&proc_lock);
+
+	list_for_each(pos, &conditions_list) {
+		var = list_entry(pos, struct condition_variable, list);
+		if (strcmp(info->name, var->status_proc->name) == 0) {
+			if (--var->refcount == 0) {
+				list_del_rcu(pos);
+				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;
+			}
+			break;
+		}
+	}
+
+	up(&proc_lock);
+}
+
+
+static struct xt_match condition_match = {
+	.name = "condition",
+	.family = PF_INET,
+	.matchsize = sizeof(struct condition_info),
+	.match = &match,
+	.checkentry = &checkentry,
+	.destroy = &destroy,
+	.me = THIS_MODULE
+};
+
+static struct xt_match condition6_match = {
+	.name = "condition",
+	.family = PF_INET6,
+	.matchsize = sizeof(struct condition_info),
+	.match = &match,
+	.checkentry = &checkentry,
+	.destroy = &destroy,
+	.me = THIS_MODULE
+};
+
+static int __init
+init(void)
+{
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,24)
+	struct proc_dir_entry * const proc_net=init_net.proc_net;
+#endif
+	int errorcode;
+
+	dir_name = compat_dir_name? "ipt_condition": "nf_condition";
+
+	proc_net_condition = proc_mkdir(dir_name, proc_net);
+	if (proc_net_condition == NULL) {
+		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
+fini(void)
+{
+	xt_unregister_match(&condition6_match);
+	xt_unregister_match(&condition_match);
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,24)
+	remove_proc_entry(dir_name, init_net.proc_net);
+#else
+	remove_proc_entry(dir_name, proc_net);
+#endif
+}
+
+module_init(init);
+module_exit(fini);

extensions/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 */

mconfig

@@ -6,5 +6,6 @@ build_ECHO=
 build_LOGMARK=m
 build_TARPIT=m
 build_TEE=m
+build_condition=m
 build_geoip=m
 build_portscan=m