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fix the backport of ipt_string by adding the linux 2.6 textsearch code in a way that does not require adding stuff to our kernel image - linux 2.6 compatible

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git-svn-id: svn://svn.openwrt.org/openwrt/trunk@5527 3c298f89-4303-0410-b956-a3cf2f4a3e73
This commit is contained in:
nbd 2006-11-14 01:45:10 +00:00
parent 6a5bc52890
commit 606cd0636d
1 changed files with 767 additions and 134 deletions
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899
target/linux/generic-2.4/patches/609-netfilter_string.patch
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@ -1,6 +1,6 @@
diff -Nur linux-2.4.32/include/linux/netfilter_ipv4/ipt_string.h linux-2.4.32.patch/include/linux/netfilter_ipv4/ipt_string.h diff -urN linux.old/include/linux/netfilter_ipv4/ipt_string.h linux.dev/include/linux/netfilter_ipv4/ipt_string.h
--- linux-2.4.32/include/linux/netfilter_ipv4/ipt_string.h 1970-01-01 01:00:00.000000000 +0100 --- linux.old/include/linux/netfilter_ipv4/ipt_string.h 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.4.32.patch/include/linux/netfilter_ipv4/ipt_string.h 2005-12-16 00:40:19.082509250 +0100 +++ linux.dev/include/linux/netfilter_ipv4/ipt_string.h 2006-11-13 23:33:31.000000000 +0100
@@ -0,0 +1,18 @@ @@ -0,0 +1,18 @@
+#ifndef _IPT_STRING_H +#ifndef _IPT_STRING_H
+#define _IPT_STRING_H +#define _IPT_STRING_H
@ -20,10 +20,444 @@ diff -Nur linux-2.4.32/include/linux/netfilter_ipv4/ipt_string.h linux-2.4.32.pa
+}; +};
+ +
+#endif /*_IPT_STRING_H*/ +#endif /*_IPT_STRING_H*/
diff -Nur linux-2.4.32/include/linux/textsearch.h linux-2.4.32.patch/include/linux/textsearch.h diff -urN linux.old/net/ipv4/netfilter/Config.in linux.dev/net/ipv4/netfilter/Config.in
--- linux-2.4.32/include/linux/textsearch.h 1970-01-01 01:00:00.000000000 +0100 --- linux.old/net/ipv4/netfilter/Config.in 2006-11-13 23:43:38.000000000 +0100
+++ linux-2.4.32.patch/include/linux/textsearch.h 2005-12-16 11:15:34.838073000 +0100 +++ linux.dev/net/ipv4/netfilter/Config.in 2006-11-13 23:33:31.000000000 +0100
@@ -0,0 +1,205 @@ @@ -52,6 +52,7 @@
fi
if [ "$CONFIG_EXPERIMENTAL" = "y" ]; then
dep_tristate ' Unclean match support (EXPERIMENTAL)' CONFIG_IP_NF_MATCH_UNCLEAN $CONFIG_IP_NF_IPTABLES
+ dep_tristate ' String match support (EXPERIMENTAL) ' CONFIG_IP_NF_MATCH_STRING $CONFIG_IP_NF_IPTABLES
dep_tristate ' Owner match support (EXPERIMENTAL)' CONFIG_IP_NF_MATCH_OWNER $CONFIG_IP_NF_IPTABLES
dep_tristate ' Layer 7 match support (EXPERIMENTAL)' CONFIG_IP_NF_MATCH_LAYER7 $CONFIG_IP_NF_CONNTRACK
dep_mbool ' Layer 7 debugging output (EXPERIMENTAL)' CONFIG_IP_NF_MATCH_LAYER7_DEBUG $CONFIG_IP_NF_MATCH_LAYER7
diff -urN linux.old/net/ipv4/netfilter/ipt_string.c linux.dev/net/ipv4/netfilter/ipt_string.c
--- linux.old/net/ipv4/netfilter/ipt_string.c 1970-01-01 01:00:00.000000000 +0100
+++ linux.dev/net/ipv4/netfilter/ipt_string.c 2006-11-14 02:26:03.000000000 +0100
@@ -0,0 +1,99 @@
+/* String matching match for iptables
+ *
+ * (C) 2005 Pablo Neira Ayuso <pablo@eurodev.net>
+ *
+ * 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/init.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/skbuff.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv4/ipt_string.h>
+#include "textsearch/textsearch.h"
+#include "textsearch/textsearch.c"
+#include "textsearch/ts_bm.c"
+#include "textsearch/ts_kmp.c"
+
+MODULE_AUTHOR("Pablo Neira Ayuso <pablo@eurodev.net>");
+MODULE_DESCRIPTION("IP tables string match module");
+MODULE_LICENSE("GPL");
+
+static int match(const struct sk_buff *skb,
+ const struct net_device *in,
+ const struct net_device *out,
+ const void *matchinfo,
+ int offset,
+ int *hotdrop)
+{
+ struct iphdr *ip = skb->nh.iph;
+ struct ts_state state;
+ struct ipt_string_info *conf = (struct ipt_string_info *) matchinfo;
+ char *buf = (char *)ip+(ip->ihl*4);
+ int len = ntohs(ip->tot_len)-(ip->ihl*4);
+
+ memset(&state, 0, sizeof(struct ts_state));
+
+ return (textsearch_find_continuous(conf->config, &state, buf, len) != UINT_MAX) && !conf->invert;
+}
+
+#define STRING_TEXT_PRIV(m) ((struct ipt_string_info *) m)
+
+static int checkentry(const char *tablename,
+ const struct ipt_ip *ip,
+ void *matchinfo,
+ unsigned int matchsize,
+ unsigned int hook_mask)
+{
+ struct ipt_string_info *conf = matchinfo;
+ struct ts_config *ts_conf;
+
+ if (matchsize != IPT_ALIGN(sizeof(struct ipt_string_info)))
+ return 0;
+
+ /* Damn, can't handle this case properly with iptables... */
+ if (conf->from_offset > conf->to_offset)
+ return 0;
+
+ ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
+ GFP_KERNEL, TS_AUTOLOAD);
+ if (IS_ERR(ts_conf))
+ return 0;
+
+ conf->config = ts_conf;
+
+ return 1;
+}
+
+static void destroy(void *matchinfo, unsigned int matchsize)
+{
+ textsearch_destroy(STRING_TEXT_PRIV(matchinfo)->config);
+}
+
+static struct ipt_match string_match = {
+ .name = "string",
+ .match = match,
+ .checkentry = checkentry,
+ .destroy = destroy,
+ .me = THIS_MODULE
+};
+
+static int __init init(void)
+{
+ init_bm();
+ init_kmp();
+ return ipt_register_match(&string_match);
+}
+
+static void __exit fini(void)
+{
+ exit_kmp();
+ exit_bm();
+ ipt_unregister_match(&string_match);
+}
+
+module_init(init);
+module_exit(fini);
diff -urN linux.old/net/ipv4/netfilter/Makefile linux.dev/net/ipv4/netfilter/Makefile
--- linux.old/net/ipv4/netfilter/Makefile 2006-11-13 23:43:38.000000000 +0100
+++ linux.dev/net/ipv4/netfilter/Makefile 2006-11-13 23:33:31.000000000 +0100
@@ -107,6 +107,7 @@
obj-$(CONFIG_IP_NF_MATCH_CONNMARK) += ipt_connmark.o
obj-$(CONFIG_IP_NF_MATCH_CONNTRACK) += ipt_conntrack.o
obj-$(CONFIG_IP_NF_MATCH_UNCLEAN) += ipt_unclean.o
+obj-$(CONFIG_IP_NF_MATCH_STRING) += ipt_string.o
obj-$(CONFIG_IP_NF_MATCH_TCPMSS) += ipt_tcpmss.o
obj-$(CONFIG_IP_NF_MATCH_LAYER7) += ipt_layer7.o
obj-$(CONFIG_IP_NF_MATCH_CONNBYTES) += ipt_connbytes.o
diff -urN linux.old/net/ipv4/netfilter/textsearch/textsearch.c linux.dev/net/ipv4/netfilter/textsearch/textsearch.c
--- linux.old/net/ipv4/netfilter/textsearch/textsearch.c 1970-01-01 01:00:00.000000000 +0100
+++ linux.dev/net/ipv4/netfilter/textsearch/textsearch.c 2006-11-14 02:31:47.000000000 +0100
@@ -0,0 +1,305 @@
+/*
+ * lib/textsearch.c Generic text search interface
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * Authors: Thomas Graf <tgraf@suug.ch>
+ * Pablo Neira Ayuso <pablo@eurodev.net>
+ *
+ * ==========================================================================
+ *
+ * INTRODUCTION
+ *
+ * The textsearch infrastructure provides text searching facitilies for
+ * both linear and non-linear data. Individual search algorithms are
+ * implemented in modules and chosen by the user.
+ *
+ * ARCHITECTURE
+ *
+ * User
+ * +----------------+
+ * | finish()|<--------------(6)-----------------+
+ * |get_next_block()|<--------------(5)---------------+ |
+ * | | Algorithm | |
+ * | | +------------------------------+
+ * | | | init() find() destroy() |
+ * | | +------------------------------+
+ * | | Core API ^ ^ ^
+ * | | +---------------+ (2) (4) (8)
+ * | (1)|----->| prepare() |---+ | |
+ * | (3)|----->| find()/next() |-----------+ |
+ * | (7)|----->| destroy() |----------------------+
+ * +----------------+ +---------------+
+ *
+ * (1) User configures a search by calling _prepare() specifying the
+ * search parameters such as the pattern and algorithm name.
+ * (2) Core requests the algorithm to allocate and initialize a search
+ * configuration according to the specified parameters.
+ * (3) User starts the search(es) by calling _find() or _next() to
+ * fetch subsequent occurrences. A state variable is provided
+ * to the algorihtm to store persistant variables.
+ * (4) Core eventually resets the search offset and forwards the find()
+ * request to the algorithm.
+ * (5) Algorithm calls get_next_block() provided by the user continously
+ * to fetch the data to be searched in block by block.
+ * (6) Algorithm invokes finish() after the last call to get_next_block
+ * to clean up any leftovers from get_next_block. (Optional)
+ * (7) User destroys the configuration by calling _destroy().
+ * (8) Core notifies the algorithm to destroy algorithm specific
+ * allocations. (Optional)
+ *
+ * USAGE
+ *
+ * Before a search can be performed, a configuration must be created
+ * by calling textsearch_prepare() specyfing the searching algorithm and
+ * the pattern to look for. The returned configuration may then be used
+ * for an arbitary amount of times and even in parallel as long as a
+ * separate struct ts_state variable is provided to every instance.
+ *
+ * The actual search is performed by either calling textsearch_find_-
+ * continuous() for linear data or by providing an own get_next_block()
+ * implementation and calling textsearch_find(). Both functions return
+ * the position of the first occurrence of the patern or UINT_MAX if
+ * no match was found. Subsequent occurences can be found by calling
+ * textsearch_next() regardless of the linearity of the data.
+ *
+ * Once you're done using a configuration it must be given back via
+ * textsearch_destroy.
+ *
+ * EXAMPLE
+ *
+ * int pos;
+ * struct ts_config *conf;
+ * struct ts_state state;
+ * const char *pattern = "chicken";
+ * const char *example = "We dance the funky chicken";
+ *
+ * conf = textsearch_prepare("kmp", pattern, strlen(pattern),
+ * GFP_KERNEL, TS_AUTOLOAD);
+ * if (IS_ERR(conf)) {
+ * err = PTR_ERR(conf);
+ * goto errout;
+ * }
+ *
+ * pos = textsearch_find_continuous(conf, &state, example, strlen(example));
+ * if (pos != UINT_MAX)
+ * panic("Oh my god, dancing chickens at %d\n", pos);
+ *
+ * textsearch_destroy(conf);
+ *
+ * ==========================================================================
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/init.h>
+#include <linux/netfilter_ipv4/lockhelp.h>
+#include "textsearch.h"
+
+static LIST_HEAD(ts_ops);
+static spinlock_t ts_mod_lock = SPIN_LOCK_UNLOCKED;
+static DECLARE_RWLOCK(ts_ops_lock);
+
+static inline struct ts_ops *lookup_ts_algo(const char *name)
+{
+ struct ts_ops *o;
+
+ read_lock(&ts_ops_lock);
+ list_for_each_entry(o, &ts_ops, list) {
+ if (!strcmp(name, o->name)) {
+ MOD_INC_USE_COUNT;
+ read_unlock(&ts_ops_lock);
+ return o;
+ }
+ }
+ read_unlock(&ts_ops_lock);
+
+ return NULL;
+}
+
+/**
+ * textsearch_register - register a textsearch module
+ * @ops: operations lookup table
+ *
+ * This function must be called by textsearch modules to announce
+ * their presence. The specified &@ops must have %name set to a
+ * unique identifier and the callbacks find(), init(), get_pattern(),
+ * and get_pattern_len() must be implemented.
+ *
+ * Returns 0 or -EEXISTS if another module has already registered
+ * with same name.
+ */
+int textsearch_register(struct ts_ops *ops)
+{
+ int err = -EEXIST;
+ struct ts_ops *o;
+
+ if (ops->name == NULL || ops->find == NULL || ops->init == NULL ||
+ ops->get_pattern == NULL || ops->get_pattern_len == NULL)
+ return -EINVAL;
+
+ spin_lock(&ts_mod_lock);
+ list_for_each_entry(o, &ts_ops, list) {
+ if (!strcmp(ops->name, o->name))
+ goto errout;
+ }
+
+ write_lock(&ts_ops_lock);
+ list_add_tail(&ops->list, &ts_ops);
+ write_unlock(&ts_ops_lock);
+
+ err = 0;
+errout:
+ spin_unlock(&ts_mod_lock);
+ return err;
+}
+
+/**
+ * textsearch_unregister - unregister a textsearch module
+ * @ops: operations lookup table
+ *
+ * This function must be called by textsearch modules to announce
+ * their disappearance for examples when the module gets unloaded.
+ * The &ops parameter must be the same as the one during the
+ * registration.
+ *
+ * Returns 0 on success or -ENOENT if no matching textsearch
+ * registration was found.
+ */
+int textsearch_unregister(struct ts_ops *ops)
+{
+ int err = 0;
+ struct ts_ops *o;
+
+ spin_lock(&ts_mod_lock);
+ list_for_each_entry(o, &ts_ops, list) {
+ if (o == ops) {
+ write_lock(&ts_ops_lock);
+ list_del(&o->list);
+ write_unlock(&ts_ops_lock);
+ goto out;
+ }
+ }
+
+ err = -ENOENT;
+out:
+ spin_unlock(&ts_mod_lock);
+ return err;
+}
+
+struct ts_linear_state
+{
+ unsigned int len;
+ const void *data;
+};
+
+static unsigned int get_linear_data(unsigned int consumed, const u8 **dst,
+ struct ts_config *conf,
+ struct ts_state *state)
+{
+ struct ts_linear_state *st = (struct ts_linear_state *) state->cb;
+
+ if (likely(consumed < st->len)) {
+ *dst = st->data + consumed;
+ return st->len - consumed;
+ }
+
+ return 0;
+}
+
+/**
+ * textsearch_find_continuous - search a pattern in continuous/linear data
+ * @conf: search configuration
+ * @state: search state
+ * @data: data to search in
+ * @len: length of data
+ *
+ * A simplified version of textsearch_find() for continuous/linear data.
+ * Call textsearch_next() to retrieve subsequent matches.
+ *
+ * Returns the position of first occurrence of the pattern or
+ * UINT_MAX if no occurrence was found.
+ */
+unsigned int textsearch_find_continuous(struct ts_config *conf,
+ struct ts_state *state,
+ const void *data, unsigned int len)
+{
+ struct ts_linear_state *st = (struct ts_linear_state *) state->cb;
+
+ conf->get_next_block = get_linear_data;
+ st->data = data;
+ st->len = len;
+
+ return textsearch_find(conf, state);
+}
+
+/**
+ * textsearch_prepare - Prepare a search
+ * @algo: name of search algorithm
+ * @pattern: pattern data
+ * @len: length of pattern
+ * @gfp_mask: allocation mask
+ * @flags: search flags
+ *
+ * Looks up the search algorithm module and creates a new textsearch
+ * configuration for the specified pattern. Upon completion all
+ * necessary refcnts are held and the configuration must be put back
+ * using textsearch_put() after usage.
+ *
+ * Note: The format of the pattern may not be compatible between
+ * the various search algorithms.
+ *
+ * Returns a new textsearch configuration according to the specified
+ * parameters or a ERR_PTR().
+ */
+struct ts_config *textsearch_prepare(const char *algo, const void *pattern,
+ unsigned int len, gfp_t gfp_mask, int flags)
+{
+ int err = -ENOENT;
+ struct ts_config *conf;
+ struct ts_ops *ops;
+
+ ops = lookup_ts_algo(algo);
+
+ if (ops == NULL)
+ goto errout;
+
+ conf = ops->init(pattern, len, gfp_mask);
+ if (IS_ERR(conf)) {
+ err = PTR_ERR(conf);
+ goto errout;
+ }
+
+ conf->ops = ops;
+ return conf;
+
+errout:
+ if (ops)
+ MOD_DEC_USE_COUNT;
+
+ return ERR_PTR(err);
+}
+
+/**
+ * textsearch_destroy - destroy a search configuration
+ * @conf: search configuration
+ *
+ * Releases all references of the configuration and frees
+ * up the memory.
+ */
+void textsearch_destroy(struct ts_config *conf)
+{
+ if (conf->ops) {
+ if (conf->ops->destroy)
+ conf->ops->destroy(conf);
+ MOD_DEC_USE_COUNT;
+ }
+
+ kfree(conf);
+}
+
diff -urN linux.old/net/ipv4/netfilter/textsearch/textsearch.h linux.dev/net/ipv4/netfilter/textsearch/textsearch.h
--- linux.old/net/ipv4/netfilter/textsearch/textsearch.h 1970-01-01 01:00:00.000000000 +0100
+++ linux.dev/net/ipv4/netfilter/textsearch/textsearch.h 2006-11-14 02:11:59.000000000 +0100
@@ -0,0 +1,182 @@
+#ifndef __LINUX_TEXTSEARCH_H +#ifndef __LINUX_TEXTSEARCH_H
+#define __LINUX_TEXTSEARCH_H +#define __LINUX_TEXTSEARCH_H
+ +
@ -35,30 +469,7 @@ diff -Nur linux-2.4.32/include/linux/textsearch.h linux-2.4.32.patch/include/lin
+#include <linux/module.h> +#include <linux/module.h>
+#include <linux/slab.h> +#include <linux/slab.h>
+ +
+#ifdef __CHECKER__ +typedef int gfp_t;
+#define __bitwise__ __attribute__((bitwise))
+#else
+#define __bitwise__
+#endif
+#ifdef __CHECK_ENDIAN__
+#define __bitwise __bitwise__
+#else
+#define __bitwise
+#endif
+
+typedef __u16 __bitwise __le16;
+typedef __u16 __bitwise __be16;
+typedef __u32 __bitwise __le32;
+typedef __u32 __bitwise __be32;
+#if defined(__GNUC__) && !defined(__STRICT_ANSI__)
+typedef __u64 __bitwise __le64;
+typedef __u64 __bitwise __be64;
+#endif
+
+#ifdef __KERNEL__
+typedef unsigned __bitwise__ gfp_t;
+#endif
+
+struct ts_config; +struct ts_config;
+ +
+/** +/**
@ -215,7 +626,7 @@ diff -Nur linux-2.4.32/include/linux/textsearch.h linux-2.4.32.patch/include/lin
+ +
+ conf = kmalloc(TS_PRIV_ALIGN(sizeof(*conf)) + payload, gfp_mask); + conf = kmalloc(TS_PRIV_ALIGN(sizeof(*conf)) + payload, gfp_mask);
+ if (conf == NULL) + if (conf == NULL)
+ return -ENOMEM; + return ERR_PTR(-ENOMEM);
+ +
+ memset(conf, 0, TS_PRIV_ALIGN(sizeof(*conf)) + payload); + memset(conf, 0, TS_PRIV_ALIGN(sizeof(*conf)) + payload);
+ return conf; + return conf;
@ -229,120 +640,342 @@ diff -Nur linux-2.4.32/include/linux/textsearch.h linux-2.4.32.patch/include/lin
+#endif /* __KERNEL__ */ +#endif /* __KERNEL__ */
+ +
+#endif +#endif
diff -Nur linux-2.4.32/net/ipv4/netfilter/Config.in linux-2.4.32.patch/net/ipv4/netfilter/Config.in diff -urN linux.old/net/ipv4/netfilter/textsearch/ts_bm.c linux.dev/net/ipv4/netfilter/textsearch/ts_bm.c
--- linux-2.4.32/net/ipv4/netfilter/Config.in 2005-01-19 15:10:13.000000000 +0100 --- linux.old/net/ipv4/netfilter/textsearch/ts_bm.c 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.4.32.patch/net/ipv4/netfilter/Config.in 2005-12-16 00:41:43.023755250 +0100 +++ linux.dev/net/ipv4/netfilter/textsearch/ts_bm.c 2006-11-14 02:22:20.000000000 +0100
@@ -42,6 +42,7 @@ @@ -0,0 +1,190 @@
fi +/*
if [ "$CONFIG_EXPERIMENTAL" = "y" ]; then + * lib/ts_bm.c Boyer-Moore text search implementation
dep_tristate ' Unclean match support (EXPERIMENTAL)' CONFIG_IP_NF_MATCH_UNCLEAN $CONFIG_IP_NF_IPTABLES
+ dep_tristate ' String match support (EXPERIMENTAL) ' CONFIG_IP_NF_MATCH_STRING $CONFIG_IP_NF_IPTABLES
dep_tristate ' Owner match support (EXPERIMENTAL)' CONFIG_IP_NF_MATCH_OWNER $CONFIG_IP_NF_IPTABLES
fi
# The targets
diff -Nur linux-2.4.32/net/ipv4/netfilter/ipt_string.c linux-2.4.32.patch/net/ipv4/netfilter/ipt_string.c
--- linux-2.4.32/net/ipv4/netfilter/ipt_string.c 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.4.32.patch/net/ipv4/netfilter/ipt_string.c 2005-12-16 00:40:48.436343750 +0100
@@ -0,0 +1,91 @@
+/* String matching match for iptables
+ * + *
+ * (C) 2005 Pablo Neira Ayuso <pablo@eurodev.net> + * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ * + *
+ * This program is free software; you can redistribute it and/or modify + * Authors: Pablo Neira Ayuso <pablo@eurodev.net>
+ * it under the terms of the GNU General Public License version 2 as + *
+ * published by the Free Software Foundation. + * ==========================================================================
+ *
+ * Implements Boyer-Moore string matching algorithm:
+ *
+ * [1] A Fast String Searching Algorithm, R.S. Boyer and Moore.
+ * Communications of the Association for Computing Machinery,
+ * 20(10), 1977, pp. 762-772.
+ * http://www.cs.utexas.edu/users/moore/publications/fstrpos.pdf
+ *
+ * [2] Handbook of Exact String Matching Algorithms, Thierry Lecroq, 2004
+ * http://www-igm.univ-mlv.fr/~lecroq/string/string.pdf
+ *
+ * Note: Since Boyer-Moore (BM) performs searches for matchings from right
+ * to left, it's still possible that a matching could be spread over
+ * multiple blocks, in that case this algorithm won't find any coincidence.
+ *
+ * If you're willing to ensure that such thing won't ever happen, use the
+ * Knuth-Pratt-Morris (KMP) implementation instead. In conclusion, choose
+ * the proper string search algorithm depending on your setting.
+ *
+ * Say you're using the textsearch infrastructure for filtering, NIDS or
+ * any similar security focused purpose, then go KMP. Otherwise, if you
+ * really care about performance, say you're classifying packets to apply
+ * Quality of Service (QoS) policies, and you don't mind about possible
+ * matchings spread over multiple fragments, then go BM.
+ */ + */
+ +
+#include <linux/init.h> +#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/kernel.h> +#include <linux/kernel.h>
+#include <linux/skbuff.h> +#include <linux/module.h>
+#include <linux/netfilter_ipv4/ip_tables.h> +#include <linux/types.h>
+#include <linux/netfilter_ipv4/ipt_string.h> +#include <linux/string.h>
+#include <linux/textsearch.h> +#include "textsearch.h"
+ +
+MODULE_AUTHOR("Pablo Neira Ayuso <pablo@eurodev.net>"); +/* Alphabet size, use ASCII */
+MODULE_DESCRIPTION("IP tables string match module"); +#define ASIZE 256
+MODULE_LICENSE("GPL");
+ +
+static int match(const struct sk_buff *skb, +#if 0
+ const struct net_device *in, +#define DEBUGP printk
+ const struct net_device *out, +#else
+ const void *matchinfo, +#define DEBUGP(args, format...)
+ int offset, +#endif
+ int *hotdrop) +
+struct ts_bm
+{ +{
+ struct ts_state state; + u8 * pattern;
+ struct ipt_string_info *conf = (struct ipt_string_info *) matchinfo; + unsigned int patlen;
+ + unsigned int bad_shift[ASIZE];
+ memset(&state, 0, sizeof(struct ts_state)); + unsigned int good_shift[0];
+
+ return (skb_find_text((struct sk_buff *)skb, conf->from_offset,
+ conf->to_offset, conf->config, &state)
+ != UINT_MAX) && !conf->invert;
+}
+
+#define STRING_TEXT_PRIV(m) ((struct ipt_string_info *) m)
+
+static int checkentry(const char *tablename,
+ const struct ipt_ip *ip,
+ void *matchinfo,
+ unsigned int matchsize,
+ unsigned int hook_mask)
+{
+ struct ipt_string_info *conf = matchinfo;
+ struct ts_config *ts_conf;
+
+ if (matchsize != IPT_ALIGN(sizeof(struct ipt_string_info)))
+ return 0;
+
+ /* Damn, can't handle this case properly with iptables... */
+ if (conf->from_offset > conf->to_offset)
+ return 0;
+
+ ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
+ GFP_KERNEL, TS_AUTOLOAD);
+ if (IS_ERR(ts_conf))
+ return 0;
+
+ conf->config = ts_conf;
+
+ return 1;
+}
+
+static void destroy(void *matchinfo, unsigned int matchsize)
+{
+ textsearch_destroy(STRING_TEXT_PRIV(matchinfo)->config);
+}
+
+static struct ipt_match string_match = {
+ .name = "string",
+ .match = match,
+ .checkentry = checkentry,
+ .destroy = destroy,
+ .me = THIS_MODULE
+}; +};
+ +
+static int __init init(void) +static unsigned int bm_find(struct ts_config *conf, struct ts_state *state)
+{ +{
+ return ipt_register_match(&string_match); + struct ts_bm *bm = ts_config_priv(conf);
+ unsigned int i, text_len, consumed = state->offset;
+ const u8 *text;
+ int shift = bm->patlen, bs;
+
+ for (;;) {
+ text_len = conf->get_next_block(consumed, &text, conf, state);
+
+ if (unlikely(text_len == 0))
+ break;
+
+ while (shift < text_len) {
+ DEBUGP("Searching in position %d (%c)\n",
+ shift, text[shift]);
+ for (i = 0; i < bm->patlen; i++)
+ if (text[shift-i] != bm->pattern[bm->patlen-1-i])
+ goto next;
+
+ /* London calling... */
+ DEBUGP("found!\n");
+ return consumed += (shift-(bm->patlen-1));
+
+next: bs = bm->bad_shift[text[shift-i]];
+
+ /* Now jumping to... */
+ shift = max_t(int, shift-i+bs, shift+bm->good_shift[i]);
+ }
+ consumed += text_len;
+ }
+
+ return UINT_MAX;
+} +}
+ +
+static void __exit fini(void) +static int subpattern(u8 *pattern, int i, int j, int g)
+{ +{
+ ipt_unregister_match(&string_match); + int x = i+g-1, y = j+g-1, ret = 0;
+
+ while(pattern[x--] == pattern[y--]) {
+ if (y < 0) {
+ ret = 1;
+ break;
+ }
+ if (--g == 0) {
+ ret = pattern[i-1] != pattern[j-1];
+ break;
+ }
+ }
+
+ return ret;
+}
+
+static void bm_compute_prefix_tbl(struct ts_bm *bm, const u8 *pattern,
+ unsigned int len)
+{
+ int i, j, g;
+
+ for (i = 0; i < ASIZE; i++)
+ bm->bad_shift[i] = len;
+ for (i = 0; i < len - 1; i++)
+ bm->bad_shift[pattern[i]] = len - 1 - i;
+
+ /* Compute the good shift array, used to match reocurrences
+ * of a subpattern */
+ bm->good_shift[0] = 1;
+ for (i = 1; i < bm->patlen; i++)
+ bm->good_shift[i] = bm->patlen;
+ for (i = bm->patlen-1, g = 1; i > 0; g++, i--) {
+ for (j = i-1; j >= 1-g ; j--)
+ if (subpattern(bm->pattern, i, j, g)) {
+ bm->good_shift[g] = bm->patlen-j-g;
+ break;
+ }
+ }
+}
+
+static struct ts_config *bm_init(const void *pattern, unsigned int len,
+ gfp_t gfp_mask)
+{
+ struct ts_config *conf;
+ struct ts_bm *bm;
+ unsigned int prefix_tbl_len = len * sizeof(unsigned int);
+ size_t priv_size = sizeof(*bm) + len + prefix_tbl_len;
+
+ conf = alloc_ts_config(priv_size, gfp_mask);
+ if (IS_ERR(conf))
+ return conf;
+
+ bm = ts_config_priv(conf);
+ bm->patlen = len;
+ bm->pattern = (u8 *) bm->good_shift + prefix_tbl_len;
+ bm_compute_prefix_tbl(bm, pattern, len);
+ memcpy(bm->pattern, pattern, len);
+
+ return conf;
+}
+
+static void *bm_get_pattern(struct ts_config *conf)
+{
+ struct ts_bm *bm = ts_config_priv(conf);
+ return bm->pattern;
+}
+
+static unsigned int bm_get_pattern_len(struct ts_config *conf)
+{
+ struct ts_bm *bm = ts_config_priv(conf);
+ return bm->patlen;
+}
+
+static struct ts_ops bm_ops = {
+ .name = "bm",
+ .find = bm_find,
+ .init = bm_init,
+ .get_pattern = bm_get_pattern,
+ .get_pattern_len = bm_get_pattern_len,
+ .owner = THIS_MODULE,
+ .list = LIST_HEAD_INIT(bm_ops.list)
+};
+
+static int __init init_bm(void)
+{
+ return textsearch_register(&bm_ops);
+}
+
+static void __exit exit_bm(void)
+{
+ textsearch_unregister(&bm_ops);
+}
diff -urN linux.old/net/ipv4/netfilter/textsearch/ts_kmp.c linux.dev/net/ipv4/netfilter/textsearch/ts_kmp.c
--- linux.old/net/ipv4/netfilter/textsearch/ts_kmp.c 1970-01-01 01:00:00.000000000 +0100
+++ linux.dev/net/ipv4/netfilter/textsearch/ts_kmp.c 2006-11-14 02:22:04.000000000 +0100
@@ -0,0 +1,141 @@
+/*
+ * lib/ts_kmp.c Knuth-Morris-Pratt text search implementation
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * Authors: Thomas Graf <tgraf@suug.ch>
+ *
+ * ==========================================================================
+ *
+ * Implements a linear-time string-matching algorithm due to Knuth,
+ * Morris, and Pratt [1]. Their algorithm avoids the explicit
+ * computation of the transition function DELTA altogether. Its
+ * matching time is O(n), for n being length(text), using just an
+ * auxiliary function PI[1..m], for m being length(pattern),
+ * precomputed from the pattern in time O(m). The array PI allows
+ * the transition function DELTA to be computed efficiently
+ * "on the fly" as needed. Roughly speaking, for any state
+ * "q" = 0,1,...,m and any character "a" in SIGMA, the value
+ * PI["q"] contains the information that is independent of "a" and
+ * is needed to compute DELTA("q", "a") [2]. Since the array PI
+ * has only m entries, whereas DELTA has O(m|SIGMA|) entries, we
+ * save a factor of |SIGMA| in the preprocessing time by computing
+ * PI rather than DELTA.
+ *
+ * [1] Cormen, Leiserson, Rivest, Stein
+ * Introdcution to Algorithms, 2nd Edition, MIT Press
+ * [2] See finite automation theory
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include "textsearch.h"
+
+struct ts_kmp
+{
+ u8 * pattern;
+ unsigned int pattern_len;
+ unsigned int prefix_tbl[0];
+};
+
+static unsigned int kmp_find(struct ts_config *conf, struct ts_state *state)
+{
+ struct ts_kmp *kmp = ts_config_priv(conf);
+ unsigned int i, q = 0, text_len, consumed = state->offset;
+ const u8 *text;
+
+ for (;;) {
+ text_len = conf->get_next_block(consumed, &text, conf, state);
+
+ if (unlikely(text_len == 0))
+ break;
+
+ for (i = 0; i < text_len; i++) {
+ while (q > 0 && kmp->pattern[q] != text[i])
+ q = kmp->prefix_tbl[q - 1];
+ if (kmp->pattern[q] == text[i])
+ q++;
+ if (unlikely(q == kmp->pattern_len)) {
+ state->offset = consumed + i + 1;
+ return state->offset - kmp->pattern_len;
+ }
+ }
+
+ consumed += text_len;
+ }
+
+ return UINT_MAX;
+}
+
+static inline void kmp_compute_prefix_tbl(const u8 *pattern, unsigned int len,
+ unsigned int *prefix_tbl)
+{
+ unsigned int k, q;
+
+ for (k = 0, q = 1; q < len; q++) {
+ while (k > 0 && pattern[k] != pattern[q])
+ k = prefix_tbl[k-1];
+ if (pattern[k] == pattern[q])
+ k++;
+ prefix_tbl[q] = k;
+ }
+}
+
+static struct ts_config *kmp_init(const void *pattern, unsigned int len,
+ gfp_t gfp_mask)
+{
+ struct ts_config *conf;
+ struct ts_kmp *kmp;
+ unsigned int prefix_tbl_len = len * sizeof(unsigned int);
+ size_t priv_size = sizeof(*kmp) + len + prefix_tbl_len;
+
+ conf = alloc_ts_config(priv_size, gfp_mask);
+ if (IS_ERR(conf))
+ return conf;
+
+ kmp = ts_config_priv(conf);
+ kmp->pattern_len = len;
+ kmp_compute_prefix_tbl(pattern, len, kmp->prefix_tbl);
+ kmp->pattern = (u8 *) kmp->prefix_tbl + prefix_tbl_len;
+ memcpy(kmp->pattern, pattern, len);
+
+ return conf;
+}
+
+static void *kmp_get_pattern(struct ts_config *conf)
+{
+ struct ts_kmp *kmp = ts_config_priv(conf);
+ return kmp->pattern;
+}
+
+static unsigned int kmp_get_pattern_len(struct ts_config *conf)
+{
+ struct ts_kmp *kmp = ts_config_priv(conf);
+ return kmp->pattern_len;
+}
+
+static struct ts_ops kmp_ops = {
+ .name = "kmp",
+ .find = kmp_find,
+ .init = kmp_init,
+ .get_pattern = kmp_get_pattern,
+ .get_pattern_len = kmp_get_pattern_len,
+ .owner = THIS_MODULE,
+ .list = LIST_HEAD_INIT(kmp_ops.list)
+};
+
+static int __init init_kmp(void)
+{
+ return textsearch_register(&kmp_ops);
+}
+
+static void __exit exit_kmp(void)
+{
+ textsearch_unregister(&kmp_ops);
+} +}
+ +
+module_init(init);
+module_exit(fini);
diff -Nur linux-2.4.32/net/ipv4/netfilter/Makefile linux-2.4.32.patch/net/ipv4/netfilter/Makefile
--- linux-2.4.32/net/ipv4/netfilter/Makefile 2003-08-25 13:44:44.000000000 +0200
+++ linux-2.4.32.patch/net/ipv4/netfilter/Makefile 2005-12-16 00:42:10.929499250 +0100
@@ -85,6 +85,7 @@
obj-$(CONFIG_IP_NF_MATCH_STATE) += ipt_state.o
obj-$(CONFIG_IP_NF_MATCH_CONNTRACK) += ipt_conntrack.o
obj-$(CONFIG_IP_NF_MATCH_UNCLEAN) += ipt_unclean.o
+obj-$(CONFIG_IP_NF_MATCH_STRING) += ipt_string.o
obj-$(CONFIG_IP_NF_MATCH_TCPMSS) += ipt_tcpmss.o
# targets