Root/target/linux/generic-2.4/patches/609-netfilter_string.patch

1--- /dev/null
2+++ b/include/linux/netfilter_ipv4/ipt_string.h
3@@ -0,0 +1,18 @@
4+#ifndef _IPT_STRING_H
5+#define _IPT_STRING_H
6+
7+#define IPT_STRING_MAX_PATTERN_SIZE 128
8+#define IPT_STRING_MAX_ALGO_NAME_SIZE 16
9+
10+struct ipt_string_info
11+{
12+ u_int16_t from_offset;
13+ u_int16_t to_offset;
14+ char algo[IPT_STRING_MAX_ALGO_NAME_SIZE];
15+ char pattern[IPT_STRING_MAX_PATTERN_SIZE];
16+ u_int8_t patlen;
17+ u_int8_t invert;
18+ struct ts_config __attribute__((aligned(8))) *config;
19+};
20+
21+#endif /*_IPT_STRING_H*/
22--- a/net/ipv4/netfilter/Config.in
23+++ b/net/ipv4/netfilter/Config.in
24@@ -47,6 +47,7 @@ if [ "$CONFIG_IP_NF_IPTABLES" != "n" ];
25   fi
26   if [ "$CONFIG_EXPERIMENTAL" = "y" ]; then
27     dep_tristate ' Unclean match support (EXPERIMENTAL)' CONFIG_IP_NF_MATCH_UNCLEAN $CONFIG_IP_NF_IPTABLES
28+ dep_tristate ' String match support (EXPERIMENTAL) ' CONFIG_IP_NF_MATCH_STRING $CONFIG_IP_NF_IPTABLES
29     dep_tristate ' Owner match support (EXPERIMENTAL)' CONFIG_IP_NF_MATCH_OWNER $CONFIG_IP_NF_IPTABLES
30     dep_tristate ' Layer 7 match support (EXPERIMENTAL)' CONFIG_IP_NF_MATCH_LAYER7 $CONFIG_IP_NF_CONNTRACK
31     dep_mbool ' Layer 7 debugging output (EXPERIMENTAL)' CONFIG_IP_NF_MATCH_LAYER7_DEBUG $CONFIG_IP_NF_MATCH_LAYER7
32--- /dev/null
33+++ b/net/ipv4/netfilter/ipt_string.c
34@@ -0,0 +1,99 @@
35+/* String matching match for iptables
36+ *
37+ * (C) 2005 Pablo Neira Ayuso <pablo@eurodev.net>
38+ *
39+ * This program is free software; you can redistribute it and/or modify
40+ * it under the terms of the GNU General Public License version 2 as
41+ * published by the Free Software Foundation.
42+ */
43+
44+#include <linux/init.h>
45+#include <linux/module.h>
46+#include <linux/kernel.h>
47+#include <linux/skbuff.h>
48+#include <linux/netfilter_ipv4/ip_tables.h>
49+#include <linux/netfilter_ipv4/ipt_string.h>
50+#include "textsearch/textsearch.h"
51+#include "textsearch/textsearch.c"
52+#include "textsearch/ts_bm.c"
53+#include "textsearch/ts_kmp.c"
54+
55+MODULE_AUTHOR("Pablo Neira Ayuso <pablo@eurodev.net>");
56+MODULE_DESCRIPTION("IP tables string match module");
57+MODULE_LICENSE("GPL");
58+
59+static int match(const struct sk_buff *skb,
60+ const struct net_device *in,
61+ const struct net_device *out,
62+ const void *matchinfo,
63+ int offset,
64+ int *hotdrop)
65+{
66+ struct iphdr *ip = skb->nh.iph;
67+ struct ts_state state;
68+ struct ipt_string_info *conf = (struct ipt_string_info *) matchinfo;
69+ char *buf = (char *)ip+(ip->ihl*4);
70+ int len = ntohs(ip->tot_len)-(ip->ihl*4);
71+
72+ memset(&state, 0, sizeof(struct ts_state));
73+
74+ return (textsearch_find_continuous(conf->config, &state, buf, len) != UINT_MAX) && !conf->invert;
75+}
76+
77+#define STRING_TEXT_PRIV(m) ((struct ipt_string_info *) m)
78+
79+static int checkentry(const char *tablename,
80+ const struct ipt_ip *ip,
81+ void *matchinfo,
82+ unsigned int matchsize,
83+ unsigned int hook_mask)
84+{
85+ struct ipt_string_info *conf = matchinfo;
86+ struct ts_config *ts_conf;
87+
88+ if (matchsize != IPT_ALIGN(sizeof(struct ipt_string_info)))
89+ return 0;
90+
91+ /* Damn, can't handle this case properly with iptables... */
92+ if (conf->from_offset > conf->to_offset)
93+ return 0;
94+
95+ ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
96+ GFP_KERNEL, TS_AUTOLOAD);
97+ if (IS_ERR(ts_conf))
98+ return 0;
99+
100+ conf->config = ts_conf;
101+
102+ return 1;
103+}
104+
105+static void destroy(void *matchinfo, unsigned int matchsize)
106+{
107+ textsearch_destroy(STRING_TEXT_PRIV(matchinfo)->config);
108+}
109+
110+static struct ipt_match string_match = {
111+ .name = "string",
112+ .match = match,
113+ .checkentry = checkentry,
114+ .destroy = destroy,
115+ .me = THIS_MODULE
116+};
117+
118+static int __init init(void)
119+{
120+ init_bm();
121+ init_kmp();
122+ return ipt_register_match(&string_match);
123+}
124+
125+static void __exit fini(void)
126+{
127+ exit_kmp();
128+ exit_bm();
129+ ipt_unregister_match(&string_match);
130+}
131+
132+module_init(init);
133+module_exit(fini);
134--- a/net/ipv4/netfilter/Makefile
135+++ b/net/ipv4/netfilter/Makefile
136@@ -87,6 +87,7 @@ obj-$(CONFIG_IP_NF_MATCH_STATE) += ipt_s
137 obj-$(CONFIG_IP_NF_MATCH_CONNMARK) += ipt_connmark.o
138 obj-$(CONFIG_IP_NF_MATCH_CONNTRACK) += ipt_conntrack.o
139 obj-$(CONFIG_IP_NF_MATCH_UNCLEAN) += ipt_unclean.o
140+obj-$(CONFIG_IP_NF_MATCH_STRING) += ipt_string.o
141 obj-$(CONFIG_IP_NF_MATCH_TCPMSS) += ipt_tcpmss.o
142 obj-$(CONFIG_IP_NF_MATCH_LAYER7) += ipt_layer7.o
143 
144--- /dev/null
145+++ b/net/ipv4/netfilter/textsearch/textsearch.c
146@@ -0,0 +1,305 @@
147+/*
148+ * lib/textsearch.c Generic text search interface
149+ *
150+ * This program is free software; you can redistribute it and/or
151+ * modify it under the terms of the GNU General Public License
152+ * as published by the Free Software Foundation; either version
153+ * 2 of the License, or (at your option) any later version.
154+ *
155+ * Authors: Thomas Graf <tgraf@suug.ch>
156+ * Pablo Neira Ayuso <pablo@eurodev.net>
157+ *
158+ * ==========================================================================
159+ *
160+ * INTRODUCTION
161+ *
162+ * The textsearch infrastructure provides text searching facitilies for
163+ * both linear and non-linear data. Individual search algorithms are
164+ * implemented in modules and chosen by the user.
165+ *
166+ * ARCHITECTURE
167+ *
168+ * User
169+ * +----------------+
170+ * | finish()|<--------------(6)-----------------+
171+ * |get_next_block()|<--------------(5)---------------+ |
172+ * | | Algorithm | |
173+ * | | +------------------------------+
174+ * | | | init() find() destroy() |
175+ * | | +------------------------------+
176+ * | | Core API ^ ^ ^
177+ * | | +---------------+ (2) (4) (8)
178+ * | (1)|----->| prepare() |---+ | |
179+ * | (3)|----->| find()/next() |-----------+ |
180+ * | (7)|----->| destroy() |----------------------+
181+ * +----------------+ +---------------+
182+ *
183+ * (1) User configures a search by calling _prepare() specifying the
184+ * search parameters such as the pattern and algorithm name.
185+ * (2) Core requests the algorithm to allocate and initialize a search
186+ * configuration according to the specified parameters.
187+ * (3) User starts the search(es) by calling _find() or _next() to
188+ * fetch subsequent occurrences. A state variable is provided
189+ * to the algorihtm to store persistant variables.
190+ * (4) Core eventually resets the search offset and forwards the find()
191+ * request to the algorithm.
192+ * (5) Algorithm calls get_next_block() provided by the user continously
193+ * to fetch the data to be searched in block by block.
194+ * (6) Algorithm invokes finish() after the last call to get_next_block
195+ * to clean up any leftovers from get_next_block. (Optional)
196+ * (7) User destroys the configuration by calling _destroy().
197+ * (8) Core notifies the algorithm to destroy algorithm specific
198+ * allocations. (Optional)
199+ *
200+ * USAGE
201+ *
202+ * Before a search can be performed, a configuration must be created
203+ * by calling textsearch_prepare() specyfing the searching algorithm and
204+ * the pattern to look for. The returned configuration may then be used
205+ * for an arbitary amount of times and even in parallel as long as a
206+ * separate struct ts_state variable is provided to every instance.
207+ *
208+ * The actual search is performed by either calling textsearch_find_-
209+ * continuous() for linear data or by providing an own get_next_block()
210+ * implementation and calling textsearch_find(). Both functions return
211+ * the position of the first occurrence of the patern or UINT_MAX if
212+ * no match was found. Subsequent occurences can be found by calling
213+ * textsearch_next() regardless of the linearity of the data.
214+ *
215+ * Once you're done using a configuration it must be given back via
216+ * textsearch_destroy.
217+ *
218+ * EXAMPLE
219+ *
220+ * int pos;
221+ * struct ts_config *conf;
222+ * struct ts_state state;
223+ * const char *pattern = "chicken";
224+ * const char *example = "We dance the funky chicken";
225+ *
226+ * conf = textsearch_prepare("kmp", pattern, strlen(pattern),
227+ * GFP_KERNEL, TS_AUTOLOAD);
228+ * if (IS_ERR(conf)) {
229+ * err = PTR_ERR(conf);
230+ * goto errout;
231+ * }
232+ *
233+ * pos = textsearch_find_continuous(conf, &state, example, strlen(example));
234+ * if (pos != UINT_MAX)
235+ * panic("Oh my god, dancing chickens at %d\n", pos);
236+ *
237+ * textsearch_destroy(conf);
238+ *
239+ * ==========================================================================
240+ */
241+
242+#include <linux/config.h>
243+#include <linux/module.h>
244+#include <linux/types.h>
245+#include <linux/string.h>
246+#include <linux/init.h>
247+#include <linux/netfilter_ipv4/lockhelp.h>
248+#include "textsearch.h"
249+
250+static LIST_HEAD(ts_ops);
251+static spinlock_t ts_mod_lock = SPIN_LOCK_UNLOCKED;
252+static DECLARE_RWLOCK(ts_ops_lock);
253+
254+static inline struct ts_ops *lookup_ts_algo(const char *name)
255+{
256+ struct ts_ops *o;
257+
258+ read_lock(&ts_ops_lock);
259+ list_for_each_entry(o, &ts_ops, list) {
260+ if (!strcmp(name, o->name)) {
261+ MOD_INC_USE_COUNT;
262+ read_unlock(&ts_ops_lock);
263+ return o;
264+ }
265+ }
266+ read_unlock(&ts_ops_lock);
267+
268+ return NULL;
269+}
270+
271+/**
272+ * textsearch_register - register a textsearch module
273+ * @ops: operations lookup table
274+ *
275+ * This function must be called by textsearch modules to announce
276+ * their presence. The specified &@ops must have %name set to a
277+ * unique identifier and the callbacks find(), init(), get_pattern(),
278+ * and get_pattern_len() must be implemented.
279+ *
280+ * Returns 0 or -EEXISTS if another module has already registered
281+ * with same name.
282+ */
283+int textsearch_register(struct ts_ops *ops)
284+{
285+ int err = -EEXIST;
286+ struct ts_ops *o;
287+
288+ if (ops->name == NULL || ops->find == NULL || ops->init == NULL ||
289+ ops->get_pattern == NULL || ops->get_pattern_len == NULL)
290+ return -EINVAL;
291+
292+ spin_lock(&ts_mod_lock);
293+ list_for_each_entry(o, &ts_ops, list) {
294+ if (!strcmp(ops->name, o->name))
295+ goto errout;
296+ }
297+
298+ write_lock(&ts_ops_lock);
299+ list_add_tail(&ops->list, &ts_ops);
300+ write_unlock(&ts_ops_lock);
301+
302+ err = 0;
303+errout:
304+ spin_unlock(&ts_mod_lock);
305+ return err;
306+}
307+
308+/**
309+ * textsearch_unregister - unregister a textsearch module
310+ * @ops: operations lookup table
311+ *
312+ * This function must be called by textsearch modules to announce
313+ * their disappearance for examples when the module gets unloaded.
314+ * The &ops parameter must be the same as the one during the
315+ * registration.
316+ *
317+ * Returns 0 on success or -ENOENT if no matching textsearch
318+ * registration was found.
319+ */
320+int textsearch_unregister(struct ts_ops *ops)
321+{
322+ int err = 0;
323+ struct ts_ops *o;
324+
325+ spin_lock(&ts_mod_lock);
326+ list_for_each_entry(o, &ts_ops, list) {
327+ if (o == ops) {
328+ write_lock(&ts_ops_lock);
329+ list_del(&o->list);
330+ write_unlock(&ts_ops_lock);
331+ goto out;
332+ }
333+ }
334+
335+ err = -ENOENT;
336+out:
337+ spin_unlock(&ts_mod_lock);
338+ return err;
339+}
340+
341+struct ts_linear_state
342+{
343+ unsigned int len;
344+ const void *data;
345+};
346+
347+static unsigned int get_linear_data(unsigned int consumed, const u8 **dst,
348+ struct ts_config *conf,
349+ struct ts_state *state)
350+{
351+ struct ts_linear_state *st = (struct ts_linear_state *) state->cb;
352+
353+ if (likely(consumed < st->len)) {
354+ *dst = st->data + consumed;
355+ return st->len - consumed;
356+ }
357+
358+ return 0;
359+}
360+
361+/**
362+ * textsearch_find_continuous - search a pattern in continuous/linear data
363+ * @conf: search configuration
364+ * @state: search state
365+ * @data: data to search in
366+ * @len: length of data
367+ *
368+ * A simplified version of textsearch_find() for continuous/linear data.
369+ * Call textsearch_next() to retrieve subsequent matches.
370+ *
371+ * Returns the position of first occurrence of the pattern or
372+ * UINT_MAX if no occurrence was found.
373+ */
374+unsigned int textsearch_find_continuous(struct ts_config *conf,
375+ struct ts_state *state,
376+ const void *data, unsigned int len)
377+{
378+ struct ts_linear_state *st = (struct ts_linear_state *) state->cb;
379+
380+ conf->get_next_block = get_linear_data;
381+ st->data = data;
382+ st->len = len;
383+
384+ return textsearch_find(conf, state);
385+}
386+
387+/**
388+ * textsearch_prepare - Prepare a search
389+ * @algo: name of search algorithm
390+ * @pattern: pattern data
391+ * @len: length of pattern
392+ * @gfp_mask: allocation mask
393+ * @flags: search flags
394+ *
395+ * Looks up the search algorithm module and creates a new textsearch
396+ * configuration for the specified pattern. Upon completion all
397+ * necessary refcnts are held and the configuration must be put back
398+ * using textsearch_put() after usage.
399+ *
400+ * Note: The format of the pattern may not be compatible between
401+ * the various search algorithms.
402+ *
403+ * Returns a new textsearch configuration according to the specified
404+ * parameters or a ERR_PTR().
405+ */
406+struct ts_config *textsearch_prepare(const char *algo, const void *pattern,
407+ unsigned int len, gfp_t gfp_mask, int flags)
408+{
409+ int err = -ENOENT;
410+ struct ts_config *conf;
411+ struct ts_ops *ops;
412+
413+ ops = lookup_ts_algo(algo);
414+
415+ if (ops == NULL)
416+ goto errout;
417+
418+ conf = ops->init(pattern, len, gfp_mask);
419+ if (IS_ERR(conf)) {
420+ err = PTR_ERR(conf);
421+ goto errout;
422+ }
423+
424+ conf->ops = ops;
425+ return conf;
426+
427+errout:
428+ if (ops)
429+ MOD_DEC_USE_COUNT;
430+
431+ return ERR_PTR(err);
432+}
433+
434+/**
435+ * textsearch_destroy - destroy a search configuration
436+ * @conf: search configuration
437+ *
438+ * Releases all references of the configuration and frees
439+ * up the memory.
440+ */
441+void textsearch_destroy(struct ts_config *conf)
442+{
443+ if (conf->ops) {
444+ if (conf->ops->destroy)
445+ conf->ops->destroy(conf);
446+ MOD_DEC_USE_COUNT;
447+ }
448+
449+ kfree(conf);
450+}
451+
452--- /dev/null
453+++ b/net/ipv4/netfilter/textsearch/textsearch.h
454@@ -0,0 +1,182 @@
455+#ifndef __LINUX_TEXTSEARCH_H
456+#define __LINUX_TEXTSEARCH_H
457+
458+#ifdef __KERNEL__
459+
460+#include <linux/types.h>
461+#include <linux/list.h>
462+#include <linux/kernel.h>
463+#include <linux/module.h>
464+#include <linux/slab.h>
465+
466+typedef int gfp_t;
467+struct ts_config;
468+
469+/**
470+ * TS_AUTOLOAD - Automatically load textsearch modules when needed
471+ */
472+#define TS_AUTOLOAD 1
473+
474+/**
475+ * struct ts_state - search state
476+ * @offset: offset for next match
477+ * @cb: control buffer, for persistant variables of get_next_block()
478+ */
479+struct ts_state
480+{
481+ unsigned int offset;
482+ char cb[40];
483+};
484+
485+/**
486+ * struct ts_ops - search module operations
487+ * @name: name of search algorithm
488+ * @init: initialization function to prepare a search
489+ * @find: find the next occurrence of the pattern
490+ * @destroy: destroy algorithm specific parts of a search configuration
491+ * @get_pattern: return head of pattern
492+ * @get_pattern_len: return length of pattern
493+ * @owner: module reference to algorithm
494+ */
495+struct ts_ops
496+{
497+ const char *name;
498+ struct ts_config * (*init)(const void *, unsigned int, gfp_t);
499+ unsigned int (*find)(struct ts_config *,
500+ struct ts_state *);
501+ void (*destroy)(struct ts_config *);
502+ void * (*get_pattern)(struct ts_config *);
503+ unsigned int (*get_pattern_len)(struct ts_config *);
504+ struct module *owner;
505+ struct list_head list;
506+};
507+
508+/**
509+ * struct ts_config - search configuration
510+ * @ops: operations of chosen algorithm
511+ * @get_next_block: callback to fetch the next block to search in
512+ * @finish: callback to finalize a search
513+ */
514+struct ts_config
515+{
516+ struct ts_ops *ops;
517+
518+ /**
519+ * get_next_block - fetch next block of data
520+ * @consumed: number of bytes consumed by the caller
521+ * @dst: destination buffer
522+ * @conf: search configuration
523+ * @state: search state
524+ *
525+ * Called repeatedly until 0 is returned. Must assign the
526+ * head of the next block of data to &*dst and return the length
527+ * of the block or 0 if at the end. consumed == 0 indicates
528+ * a new search. May store/read persistant values in state->cb.
529+ */
530+ unsigned int (*get_next_block)(unsigned int consumed,
531+ const u8 **dst,
532+ struct ts_config *conf,
533+ struct ts_state *state);
534+
535+ /**
536+ * finish - finalize/clean a series of get_next_block() calls
537+ * @conf: search configuration
538+ * @state: search state
539+ *
540+ * Called after the last use of get_next_block(), may be used
541+ * to cleanup any leftovers.
542+ */
543+ void (*finish)(struct ts_config *conf,
544+ struct ts_state *state);
545+};
546+
547+/**
548+ * textsearch_next - continue searching for a pattern
549+ * @conf: search configuration
550+ * @state: search state
551+ *
552+ * Continues a search looking for more occurrences of the pattern.
553+ * textsearch_find() must be called to find the first occurrence
554+ * in order to reset the state.
555+ *
556+ * Returns the position of the next occurrence of the pattern or
557+ * UINT_MAX if not match was found.
558+ */
559+static inline unsigned int textsearch_next(struct ts_config *conf,
560+ struct ts_state *state)
561+{
562+ unsigned int ret = conf->ops->find(conf, state);
563+
564+ if (conf->finish)
565+ conf->finish(conf, state);
566+
567+ return ret;
568+}
569+
570+/**
571+ * textsearch_find - start searching for a pattern
572+ * @conf: search configuration
573+ * @state: search state
574+ *
575+ * Returns the position of first occurrence of the pattern or
576+ * UINT_MAX if no match was found.
577+ */
578+static inline unsigned int textsearch_find(struct ts_config *conf,
579+ struct ts_state *state)
580+{
581+ state->offset = 0;
582+ return textsearch_next(conf, state);
583+}
584+
585+/**
586+ * textsearch_get_pattern - return head of the pattern
587+ * @conf: search configuration
588+ */
589+static inline void *textsearch_get_pattern(struct ts_config *conf)
590+{
591+ return conf->ops->get_pattern(conf);
592+}
593+
594+/**
595+ * textsearch_get_pattern_len - return length of the pattern
596+ * @conf: search configuration
597+ */
598+static inline unsigned int textsearch_get_pattern_len(struct ts_config *conf)
599+{
600+ return conf->ops->get_pattern_len(conf);
601+}
602+
603+extern int textsearch_register(struct ts_ops *);
604+extern int textsearch_unregister(struct ts_ops *);
605+extern struct ts_config *textsearch_prepare(const char *, const void *,
606+ unsigned int, gfp_t, int);
607+extern void textsearch_destroy(struct ts_config *conf);
608+extern unsigned int textsearch_find_continuous(struct ts_config *,
609+ struct ts_state *,
610+ const void *, unsigned int);
611+
612+
613+#define TS_PRIV_ALIGNTO 8
614+#define TS_PRIV_ALIGN(len) (((len) + TS_PRIV_ALIGNTO-1) & ~(TS_PRIV_ALIGNTO-1))
615+
616+static inline struct ts_config *alloc_ts_config(size_t payload,
617+ gfp_t gfp_mask)
618+{
619+ struct ts_config *conf;
620+
621+ conf = kmalloc(TS_PRIV_ALIGN(sizeof(*conf)) + payload, gfp_mask);
622+ if (conf == NULL)
623+ return ERR_PTR(-ENOMEM);
624+
625+ memset(conf, 0, TS_PRIV_ALIGN(sizeof(*conf)) + payload);
626+ return conf;
627+}
628+
629+static inline void *ts_config_priv(struct ts_config *conf)
630+{
631+ return ((u8 *) conf + TS_PRIV_ALIGN(sizeof(struct ts_config)));
632+}
633+
634+#endif /* __KERNEL__ */
635+
636+#endif
637--- /dev/null
638+++ b/net/ipv4/netfilter/textsearch/ts_bm.c
639@@ -0,0 +1,190 @@
640+/*
641+ * lib/ts_bm.c Boyer-Moore text search implementation
642+ *
643+ * This program is free software; you can redistribute it and/or
644+ * modify it under the terms of the GNU General Public License
645+ * as published by the Free Software Foundation; either version
646+ * 2 of the License, or (at your option) any later version.
647+ *
648+ * Authors: Pablo Neira Ayuso <pablo@eurodev.net>
649+ *
650+ * ==========================================================================
651+ *
652+ * Implements Boyer-Moore string matching algorithm:
653+ *
654+ * [1] A Fast String Searching Algorithm, R.S. Boyer and Moore.
655+ * Communications of the Association for Computing Machinery,
656+ * 20(10), 1977, pp. 762-772.
657+ * http://www.cs.utexas.edu/users/moore/publications/fstrpos.pdf
658+ *
659+ * [2] Handbook of Exact String Matching Algorithms, Thierry Lecroq, 2004
660+ * http://www-igm.univ-mlv.fr/~lecroq/string/string.pdf
661+ *
662+ * Note: Since Boyer-Moore (BM) performs searches for matchings from right
663+ * to left, it's still possible that a matching could be spread over
664+ * multiple blocks, in that case this algorithm won't find any coincidence.
665+ *
666+ * If you're willing to ensure that such thing won't ever happen, use the
667+ * Knuth-Pratt-Morris (KMP) implementation instead. In conclusion, choose
668+ * the proper string search algorithm depending on your setting.
669+ *
670+ * Say you're using the textsearch infrastructure for filtering, NIDS or
671+ * any similar security focused purpose, then go KMP. Otherwise, if you
672+ * really care about performance, say you're classifying packets to apply
673+ * Quality of Service (QoS) policies, and you don't mind about possible
674+ * matchings spread over multiple fragments, then go BM.
675+ */
676+
677+#include <linux/config.h>
678+#include <linux/kernel.h>
679+#include <linux/module.h>
680+#include <linux/types.h>
681+#include <linux/string.h>
682+#include "textsearch.h"
683+
684+/* Alphabet size, use ASCII */
685+#define ASIZE 256
686+
687+#if 0
688+#define DEBUGP printk
689+#else
690+#define DEBUGP(args, format...)
691+#endif
692+
693+struct ts_bm
694+{
695+ u8 * pattern;
696+ unsigned int patlen;
697+ unsigned int bad_shift[ASIZE];
698+ unsigned int good_shift[0];
699+};
700+
701+static unsigned int bm_find(struct ts_config *conf, struct ts_state *state)
702+{
703+ struct ts_bm *bm = ts_config_priv(conf);
704+ unsigned int i, text_len, consumed = state->offset;
705+ const u8 *text;
706+ int shift = bm->patlen, bs;
707+
708+ for (;;) {
709+ text_len = conf->get_next_block(consumed, &text, conf, state);
710+
711+ if (unlikely(text_len == 0))
712+ break;
713+
714+ while (shift < text_len) {
715+ DEBUGP("Searching in position %d (%c)\n",
716+ shift, text[shift]);
717+ for (i = 0; i < bm->patlen; i++)
718+ if (text[shift-i] != bm->pattern[bm->patlen-1-i])
719+ goto next;
720+
721+ /* London calling... */
722+ DEBUGP("found!\n");
723+ return consumed += (shift-(bm->patlen-1));
724+
725+next: bs = bm->bad_shift[text[shift-i]];
726+
727+ /* Now jumping to... */
728+ shift = max_t(int, shift-i+bs, shift+bm->good_shift[i]);
729+ }
730+ consumed += text_len;
731+ }
732+
733+ return UINT_MAX;
734+}
735+
736+static int subpattern(u8 *pattern, int i, int j, int g)
737+{
738+ int x = i+g-1, y = j+g-1, ret = 0;
739+
740+ while(pattern[x--] == pattern[y--]) {
741+ if (y < 0) {
742+ ret = 1;
743+ break;
744+ }
745+ if (--g == 0) {
746+ ret = pattern[i-1] != pattern[j-1];
747+ break;
748+ }
749+ }
750+
751+ return ret;
752+}
753+
754+static void bm_compute_prefix_tbl(struct ts_bm *bm, const u8 *pattern,
755+ unsigned int len)
756+{
757+ int i, j, g;
758+
759+ for (i = 0; i < ASIZE; i++)
760+ bm->bad_shift[i] = len;
761+ for (i = 0; i < len - 1; i++)
762+ bm->bad_shift[pattern[i]] = len - 1 - i;
763+
764+ /* Compute the good shift array, used to match reocurrences
765+ * of a subpattern */
766+ bm->good_shift[0] = 1;
767+ for (i = 1; i < bm->patlen; i++)
768+ bm->good_shift[i] = bm->patlen;
769+ for (i = bm->patlen-1, g = 1; i > 0; g++, i--) {
770+ for (j = i-1; j >= 1-g ; j--)
771+ if (subpattern(bm->pattern, i, j, g)) {
772+ bm->good_shift[g] = bm->patlen-j-g;
773+ break;
774+ }
775+ }
776+}
777+
778+static struct ts_config *bm_init(const void *pattern, unsigned int len,
779+ gfp_t gfp_mask)
780+{
781+ struct ts_config *conf;
782+ struct ts_bm *bm;
783+ unsigned int prefix_tbl_len = len * sizeof(unsigned int);
784+ size_t priv_size = sizeof(*bm) + len + prefix_tbl_len;
785+
786+ conf = alloc_ts_config(priv_size, gfp_mask);
787+ if (IS_ERR(conf))
788+ return conf;
789+
790+ bm = ts_config_priv(conf);
791+ bm->patlen = len;
792+ bm->pattern = (u8 *) bm->good_shift + prefix_tbl_len;
793+ bm_compute_prefix_tbl(bm, pattern, len);
794+ memcpy(bm->pattern, pattern, len);
795+
796+ return conf;
797+}
798+
799+static void *bm_get_pattern(struct ts_config *conf)
800+{
801+ struct ts_bm *bm = ts_config_priv(conf);
802+ return bm->pattern;
803+}
804+
805+static unsigned int bm_get_pattern_len(struct ts_config *conf)
806+{
807+ struct ts_bm *bm = ts_config_priv(conf);
808+ return bm->patlen;
809+}
810+
811+static struct ts_ops bm_ops = {
812+ .name = "bm",
813+ .find = bm_find,
814+ .init = bm_init,
815+ .get_pattern = bm_get_pattern,
816+ .get_pattern_len = bm_get_pattern_len,
817+ .owner = THIS_MODULE,
818+ .list = LIST_HEAD_INIT(bm_ops.list)
819+};
820+
821+static int __init init_bm(void)
822+{
823+ return textsearch_register(&bm_ops);
824+}
825+
826+static void __exit exit_bm(void)
827+{
828+ textsearch_unregister(&bm_ops);
829+}
830--- /dev/null
831+++ b/net/ipv4/netfilter/textsearch/ts_kmp.c
832@@ -0,0 +1,141 @@
833+/*
834+ * lib/ts_kmp.c Knuth-Morris-Pratt text search implementation
835+ *
836+ * This program is free software; you can redistribute it and/or
837+ * modify it under the terms of the GNU General Public License
838+ * as published by the Free Software Foundation; either version
839+ * 2 of the License, or (at your option) any later version.
840+ *
841+ * Authors: Thomas Graf <tgraf@suug.ch>
842+ *
843+ * ==========================================================================
844+ *
845+ * Implements a linear-time string-matching algorithm due to Knuth,
846+ * Morris, and Pratt [1]. Their algorithm avoids the explicit
847+ * computation of the transition function DELTA altogether. Its
848+ * matching time is O(n), for n being length(text), using just an
849+ * auxiliary function PI[1..m], for m being length(pattern),
850+ * precomputed from the pattern in time O(m). The array PI allows
851+ * the transition function DELTA to be computed efficiently
852+ * "on the fly" as needed. Roughly speaking, for any state
853+ * "q" = 0,1,...,m and any character "a" in SIGMA, the value
854+ * PI["q"] contains the information that is independent of "a" and
855+ * is needed to compute DELTA("q", "a") [2]. Since the array PI
856+ * has only m entries, whereas DELTA has O(m|SIGMA|) entries, we
857+ * save a factor of |SIGMA| in the preprocessing time by computing
858+ * PI rather than DELTA.
859+ *
860+ * [1] Cormen, Leiserson, Rivest, Stein
861+ * Introdcution to Algorithms, 2nd Edition, MIT Press
862+ * [2] See finite automation theory
863+ */
864+
865+#include <linux/config.h>
866+#include <linux/module.h>
867+#include <linux/types.h>
868+#include <linux/string.h>
869+#include "textsearch.h"
870+
871+struct ts_kmp
872+{
873+ u8 * pattern;
874+ unsigned int pattern_len;
875+ unsigned int prefix_tbl[0];
876+};
877+
878+static unsigned int kmp_find(struct ts_config *conf, struct ts_state *state)
879+{
880+ struct ts_kmp *kmp = ts_config_priv(conf);
881+ unsigned int i, q = 0, text_len, consumed = state->offset;
882+ const u8 *text;
883+
884+ for (;;) {
885+ text_len = conf->get_next_block(consumed, &text, conf, state);
886+
887+ if (unlikely(text_len == 0))
888+ break;
889+
890+ for (i = 0; i < text_len; i++) {
891+ while (q > 0 && kmp->pattern[q] != text[i])
892+ q = kmp->prefix_tbl[q - 1];
893+ if (kmp->pattern[q] == text[i])
894+ q++;
895+ if (unlikely(q == kmp->pattern_len)) {
896+ state->offset = consumed + i + 1;
897+ return state->offset - kmp->pattern_len;
898+ }
899+ }
900+
901+ consumed += text_len;
902+ }
903+
904+ return UINT_MAX;
905+}
906+
907+static inline void kmp_compute_prefix_tbl(const u8 *pattern, unsigned int len,
908+ unsigned int *prefix_tbl)
909+{
910+ unsigned int k, q;
911+
912+ for (k = 0, q = 1; q < len; q++) {
913+ while (k > 0 && pattern[k] != pattern[q])
914+ k = prefix_tbl[k-1];
915+ if (pattern[k] == pattern[q])
916+ k++;
917+ prefix_tbl[q] = k;
918+ }
919+}
920+
921+static struct ts_config *kmp_init(const void *pattern, unsigned int len,
922+ gfp_t gfp_mask)
923+{
924+ struct ts_config *conf;
925+ struct ts_kmp *kmp;
926+ unsigned int prefix_tbl_len = len * sizeof(unsigned int);
927+ size_t priv_size = sizeof(*kmp) + len + prefix_tbl_len;
928+
929+ conf = alloc_ts_config(priv_size, gfp_mask);
930+ if (IS_ERR(conf))
931+ return conf;
932+
933+ kmp = ts_config_priv(conf);
934+ kmp->pattern_len = len;
935+ kmp_compute_prefix_tbl(pattern, len, kmp->prefix_tbl);
936+ kmp->pattern = (u8 *) kmp->prefix_tbl + prefix_tbl_len;
937+ memcpy(kmp->pattern, pattern, len);
938+
939+ return conf;
940+}
941+
942+static void *kmp_get_pattern(struct ts_config *conf)
943+{
944+ struct ts_kmp *kmp = ts_config_priv(conf);
945+ return kmp->pattern;
946+}
947+
948+static unsigned int kmp_get_pattern_len(struct ts_config *conf)
949+{
950+ struct ts_kmp *kmp = ts_config_priv(conf);
951+ return kmp->pattern_len;
952+}
953+
954+static struct ts_ops kmp_ops = {
955+ .name = "kmp",
956+ .find = kmp_find,
957+ .init = kmp_init,
958+ .get_pattern = kmp_get_pattern,
959+ .get_pattern_len = kmp_get_pattern_len,
960+ .owner = THIS_MODULE,
961+ .list = LIST_HEAD_INIT(kmp_ops.list)
962+};
963+
964+static int __init init_kmp(void)
965+{
966+ return textsearch_register(&kmp_ops);
967+}
968+
969+static void __exit exit_kmp(void)
970+{
971+ textsearch_unregister(&kmp_ops);
972+}
973+
974

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