security/apparmor/match.c - kernel/msm-4.19 - Gitiles

 /*
  * AppArmor security module
  *
  * This file contains AppArmor dfa based regular expression matching engine
  *
  * Copyright (C) 1998-2008 Novell/SUSE
  * Copyright 2009-2012 Canonical Ltd.
  *
  * 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, version 2 of the
  * License.
  */

 #include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/err.h>
 #include <linux/kref.h>

 #include "include/lib.h"
 #include "include/match.h"

 #define base_idx(X) ((X) & 0xffffff)

 static char nulldfa_src[] = {
 	#include "nulldfa.in"
 };
 struct aa_dfa *nulldfa;

 int aa_setup_dfa_engine(void)
 {
 	int error;

 	nulldfa = aa_dfa_unpack(nulldfa_src, sizeof(nulldfa_src),
 				TO_ACCEPT1_FLAG(YYTD_DATA32) |
 				TO_ACCEPT2_FLAG(YYTD_DATA32));
 	if (!IS_ERR(nulldfa))
 		return 0;

 	error = PTR_ERR(nulldfa);
 	nulldfa = NULL;

 	return error;
 }

 void aa_teardown_dfa_engine(void)
 {
 	aa_put_dfa(nulldfa);
 	nulldfa = NULL;
 }

 /**
  * unpack_table - unpack a dfa table (one of accept, default, base, next check)
  * @blob: data to unpack (NOT NULL)
  * @bsize: size of blob
  *
  * Returns: pointer to table else NULL on failure
  *
  * NOTE: must be freed by kvfree (not kfree)
  */
 static struct table_header *unpack_table(char *blob, size_t bsize)
 {
 	struct table_header *table = NULL;
 	struct table_header th;
 	size_t tsize;

 	if (bsize < sizeof(struct table_header))
 		goto out;

 	/* loaded td_id's start at 1, subtract 1 now to avoid doing
 	 * it every time we use td_id as an index
 	 */
 	th.td_id = be16_to_cpu(*(__be16 *) (blob)) - 1;
 	if (th.td_id > YYTD_ID_MAX)
 		goto out;
 	th.td_flags = be16_to_cpu(*(__be16 *) (blob + 2));
 	th.td_lolen = be32_to_cpu(*(__be32 *) (blob + 8));
 	blob += sizeof(struct table_header);

 	if (!(th.td_flags == YYTD_DATA16 || th.td_flags == YYTD_DATA32 ||
 	      th.td_flags == YYTD_DATA8))
 		goto out;

 	tsize = table_size(th.td_lolen, th.td_flags);
 	if (bsize < tsize)
 		goto out;

 	table = kvzalloc(tsize);
 	if (table) {
 		table->td_id = th.td_id;
 		table->td_flags = th.td_flags;
 		table->td_lolen = th.td_lolen;
 		if (th.td_flags == YYTD_DATA8)
 			UNPACK_ARRAY(table->td_data, blob, th.td_lolen,
 				     u8, u8, byte_to_byte);
 		else if (th.td_flags == YYTD_DATA16)
 			UNPACK_ARRAY(table->td_data, blob, th.td_lolen,
 				     u16, __be16, be16_to_cpu);
 		else if (th.td_flags == YYTD_DATA32)
 			UNPACK_ARRAY(table->td_data, blob, th.td_lolen,
 				     u32, __be32, be32_to_cpu);
 		else
 			goto fail;
 		/* if table was vmalloced make sure the page tables are synced
 		 * before it is used, as it goes live to all cpus.
 		 */
 		if (is_vmalloc_addr(table))
 			vm_unmap_aliases();
 	}

 out:
 	return table;
 fail:
 	kvfree(table);
 	return NULL;
 }

 /**
  * verify_dfa - verify that transitions and states in the tables are in bounds.
  * @dfa: dfa to test  (NOT NULL)
  * @flags: flags controlling what type of accept table are acceptable
  *
  * Assumes dfa has gone through the first pass verification done by unpacking
  * NOTE: this does not valid accept table values
  *
  * Returns: %0 else error code on failure to verify
  */
 static int verify_dfa(struct aa_dfa *dfa, int flags)
 {
 	size_t i, state_count, trans_count;
 	int error = -EPROTO;

 	/* check that required tables exist */
 	if (!(dfa->tables[YYTD_ID_DEF] &&
 	      dfa->tables[YYTD_ID_BASE] &&
 	      dfa->tables[YYTD_ID_NXT] && dfa->tables[YYTD_ID_CHK]))
 		goto out;

 	/* accept.size == default.size == base.size */
 	state_count = dfa->tables[YYTD_ID_BASE]->td_lolen;
 	if (ACCEPT1_FLAGS(flags)) {
 		if (!dfa->tables[YYTD_ID_ACCEPT])
 			goto out;
 		if (state_count != dfa->tables[YYTD_ID_ACCEPT]->td_lolen)
 			goto out;
 	}
 	if (ACCEPT2_FLAGS(flags)) {
 		if (!dfa->tables[YYTD_ID_ACCEPT2])
 			goto out;
 		if (state_count != dfa->tables[YYTD_ID_ACCEPT2]->td_lolen)
 			goto out;
 	}
 	if (state_count != dfa->tables[YYTD_ID_DEF]->td_lolen)
 		goto out;

 	/* next.size == chk.size */
 	trans_count = dfa->tables[YYTD_ID_NXT]->td_lolen;
 	if (trans_count != dfa->tables[YYTD_ID_CHK]->td_lolen)
 		goto out;

 	/* if equivalence classes then its table size must be 256 */
 	if (dfa->tables[YYTD_ID_EC] &&
 	    dfa->tables[YYTD_ID_EC]->td_lolen != 256)
 		goto out;

 	if (flags & DFA_FLAG_VERIFY_STATES) {
 		for (i = 0; i < state_count; i++) {
 			if (DEFAULT_TABLE(dfa)[i] >= state_count)
 				goto out;
 			if (base_idx(BASE_TABLE(dfa)[i]) + 255 >= trans_count) {
 				printk(KERN_ERR "AppArmor DFA next/check upper "
 				       "bounds error\n");
 				goto out;
 			}
 		}

 		for (i = 0; i < trans_count; i++) {
 			if (NEXT_TABLE(dfa)[i] >= state_count)
 				goto out;
 			if (CHECK_TABLE(dfa)[i] >= state_count)
 				goto out;
 		}
 	}

 	error = 0;
 out:
 	return error;
 }

 /**
  * dfa_free - free a dfa allocated by aa_dfa_unpack
  * @dfa: the dfa to free  (MAYBE NULL)
  *
  * Requires: reference count to dfa == 0
  */
 static void dfa_free(struct aa_dfa *dfa)
 {
 	if (dfa) {
 		int i;

 		for (i = 0; i < ARRAY_SIZE(dfa->tables); i++) {
 			kvfree(dfa->tables[i]);
 			dfa->tables[i] = NULL;
 		}
 		kfree(dfa);
 	}
 }

 /**
  * aa_dfa_free_kref - free aa_dfa by kref (called by aa_put_dfa)
  * @kr: kref callback for freeing of a dfa  (NOT NULL)
  */
 void aa_dfa_free_kref(struct kref *kref)
 {
 	struct aa_dfa *dfa = container_of(kref, struct aa_dfa, count);
 	dfa_free(dfa);
 }

 /**
  * aa_dfa_unpack - unpack the binary tables of a serialized dfa
  * @blob: aligned serialized stream of data to unpack  (NOT NULL)
  * @size: size of data to unpack
  * @flags: flags controlling what type of accept tables are acceptable
  *
  * Unpack a dfa that has been serialized.  To find information on the dfa
  * format look in Documentation/security/apparmor.txt
  * Assumes the dfa @blob stream has been aligned on a 8 byte boundary
  *
  * Returns: an unpacked dfa ready for matching or ERR_PTR on failure
  */
 struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags)
 {
 	int hsize;
 	int error = -ENOMEM;
 	char *data = blob;
 	struct table_header *table = NULL;
 	struct aa_dfa *dfa = kzalloc(sizeof(struct aa_dfa), GFP_KERNEL);
 	if (!dfa)
 		goto fail;

 	kref_init(&dfa->count);

 	error = -EPROTO;

 	/* get dfa table set header */
 	if (size < sizeof(struct table_set_header))
 		goto fail;

 	if (ntohl(*(__be32 *) data) != YYTH_MAGIC)
 		goto fail;

 	hsize = ntohl(*(__be32 *) (data + 4));
 	if (size < hsize)
 		goto fail;

 	dfa->flags = ntohs(*(__be16 *) (data + 12));
 	data += hsize;
 	size -= hsize;

 	while (size > 0) {
 		table = unpack_table(data, size);
 		if (!table)
 			goto fail;

 		switch (table->td_id) {
 		case YYTD_ID_ACCEPT:
 			if (!(table->td_flags & ACCEPT1_FLAGS(flags)))
 				goto fail;
 			break;
 		case YYTD_ID_ACCEPT2:
 			if (!(table->td_flags & ACCEPT2_FLAGS(flags)))
 				goto fail;
 			break;
 		case YYTD_ID_BASE:
 			if (table->td_flags != YYTD_DATA32)
 				goto fail;
 			break;
 		case YYTD_ID_DEF:
 		case YYTD_ID_NXT:
 		case YYTD_ID_CHK:
 			if (table->td_flags != YYTD_DATA16)
 				goto fail;
 			break;
 		case YYTD_ID_EC:
 			if (table->td_flags != YYTD_DATA8)
 				goto fail;
 			break;
 		default:
 			goto fail;
 		}
 		/* check for duplicate table entry */
 		if (dfa->tables[table->td_id])
 			goto fail;
 		dfa->tables[table->td_id] = table;
 		data += table_size(table->td_lolen, table->td_flags);
 		size -= table_size(table->td_lolen, table->td_flags);
 		table = NULL;
 	}

 	error = verify_dfa(dfa, flags);
 	if (error)
 		goto fail;

 	return dfa;

 fail:
 	kvfree(table);
 	dfa_free(dfa);
 	return ERR_PTR(error);
 }

 /**
  * aa_dfa_match_len - traverse @dfa to find state @str stops at
  * @dfa: the dfa to match @str against  (NOT NULL)
  * @start: the state of the dfa to start matching in
  * @str: the string of bytes to match against the dfa  (NOT NULL)
  * @len: length of the string of bytes to match
  *
  * aa_dfa_match_len will match @str against the dfa and return the state it
  * finished matching in. The final state can be used to look up the accepting
  * label, or as the start state of a continuing match.
  *
  * This function will happily match again the 0 byte and only finishes
  * when @len input is consumed.
  *
  * Returns: final state reached after input is consumed
  */
 unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
 			      const char *str, int len)
 {
 	u16 *def = DEFAULT_TABLE(dfa);
 	u32 *base = BASE_TABLE(dfa);
 	u16 *next = NEXT_TABLE(dfa);
 	u16 *check = CHECK_TABLE(dfa);
 	unsigned int state = start, pos;

 	if (state == 0)
 		return 0;

 	/* current state is <state>, matching character *str */
 	if (dfa->tables[YYTD_ID_EC]) {
 		/* Equivalence class table defined */
 		u8 *equiv = EQUIV_TABLE(dfa);
 		/* default is direct to next state */
 		for (; len; len--) {
 			pos = base_idx(base[state]) + equiv[(u8) *str++];
 			if (check[pos] == state)
 				state = next[pos];
 			else
 				state = def[state];
 		}
 	} else {
 		/* default is direct to next state */
 		for (; len; len--) {
 			pos = base_idx(base[state]) + (u8) *str++;
 			if (check[pos] == state)
 				state = next[pos];
 			else
 				state = def[state];
 		}
 	}

 	return state;
 }

 /**
  * aa_dfa_match - traverse @dfa to find state @str stops at
  * @dfa: the dfa to match @str against  (NOT NULL)
  * @start: the state of the dfa to start matching in
  * @str: the null terminated string of bytes to match against the dfa (NOT NULL)
  *
  * aa_dfa_match will match @str against the dfa and return the state it
  * finished matching in. The final state can be used to look up the accepting
  * label, or as the start state of a continuing match.
  *
  * Returns: final state reached after input is consumed
  */
 unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
 			  const char *str)
 {
 	u16 *def = DEFAULT_TABLE(dfa);
 	u32 *base = BASE_TABLE(dfa);
 	u16 *next = NEXT_TABLE(dfa);
 	u16 *check = CHECK_TABLE(dfa);
 	unsigned int state = start, pos;

 	if (state == 0)
 		return 0;

 	/* current state is <state>, matching character *str */
 	if (dfa->tables[YYTD_ID_EC]) {
 		/* Equivalence class table defined */
 		u8 *equiv = EQUIV_TABLE(dfa);
 		/* default is direct to next state */
 		while (*str) {
 			pos = base_idx(base[state]) + equiv[(u8) *str++];
 			if (check[pos] == state)
 				state = next[pos];
 			else
 				state = def[state];
 		}
 	} else {
 		/* default is direct to next state */
 		while (*str) {
 			pos = base_idx(base[state]) + (u8) *str++;
 			if (check[pos] == state)
 				state = next[pos];
 			else
 				state = def[state];
 		}
 	}

 	return state;
 }

 /**
  * aa_dfa_next - step one character to the next state in the dfa
  * @dfa: the dfa to tranverse (NOT NULL)
  * @state: the state to start in
  * @c: the input character to transition on
  *
  * aa_dfa_match will step through the dfa by one input character @c
  *
  * Returns: state reach after input @c
  */
 unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
 			  const char c)
 {
 	u16 *def = DEFAULT_TABLE(dfa);
 	u32 *base = BASE_TABLE(dfa);
 	u16 *next = NEXT_TABLE(dfa);
 	u16 *check = CHECK_TABLE(dfa);
 	unsigned int pos;

 	/* current state is <state>, matching character *str */
 	if (dfa->tables[YYTD_ID_EC]) {
 		/* Equivalence class table defined */
 		u8 *equiv = EQUIV_TABLE(dfa);
 		/* default is direct to next state */

 		pos = base_idx(base[state]) + equiv[(u8) c];
 		if (check[pos] == state)
 			state = next[pos];
 		else
 			state = def[state];
 	} else {
 		/* default is direct to next state */
 		pos = base_idx(base[state]) + (u8) c;
 		if (check[pos] == state)
 			state = next[pos];
 		else
 			state = def[state];
 	}

 	return state;
 }
	/*
	* AppArmor security module
	*
	* This file contains AppArmor dfa based regular expression matching engine
	*
	* Copyright (C) 1998-2008 Novell/SUSE
	* Copyright 2009-2012 Canonical Ltd.
	*
	* 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, version 2 of the
	* License.
	*/

	#include <linux/errno.h>
	#include <linux/kernel.h>
	#include <linux/mm.h>
	#include <linux/slab.h>
	#include <linux/vmalloc.h>
	#include <linux/err.h>
	#include <linux/kref.h>

	#include "include/lib.h"
	#include "include/match.h"

	#define base_idx(X) ((X) & 0xffffff)

	static char nulldfa_src[] = {
	#include "nulldfa.in"
	};
	struct aa_dfa *nulldfa;

	int aa_setup_dfa_engine(void)
	{
	int error;

	nulldfa = aa_dfa_unpack(nulldfa_src, sizeof(nulldfa_src),
	TO_ACCEPT1_FLAG(YYTD_DATA32) \|
	TO_ACCEPT2_FLAG(YYTD_DATA32));
	if (!IS_ERR(nulldfa))
	return 0;

	error = PTR_ERR(nulldfa);
	nulldfa = NULL;

	return error;
	}

	void aa_teardown_dfa_engine(void)
	{
	aa_put_dfa(nulldfa);
	nulldfa = NULL;
	}

	/**
	* unpack_table - unpack a dfa table (one of accept, default, base, next check)
	* @blob: data to unpack (NOT NULL)
	* @bsize: size of blob
	*
	* Returns: pointer to table else NULL on failure
	*
	* NOTE: must be freed by kvfree (not kfree)
	*/
	static struct table_header unpack_table(char blob, size_t bsize)
	{
	struct table_header *table = NULL;
	struct table_header th;
	size_t tsize;

	if (bsize < sizeof(struct table_header))
	goto out;

	/* loaded td_id's start at 1, subtract 1 now to avoid doing
	* it every time we use td_id as an index
	*/
	th.td_id = be16_to_cpu((__be16 ) (blob)) - 1;
	if (th.td_id > YYTD_ID_MAX)
	goto out;
	th.td_flags = be16_to_cpu((__be16 ) (blob + 2));
	th.td_lolen = be32_to_cpu((__be32 ) (blob + 8));
	blob += sizeof(struct table_header);

	if (!(th.td_flags == YYTD_DATA16 \|\| th.td_flags == YYTD_DATA32 \|\|
	th.td_flags == YYTD_DATA8))
	goto out;

	tsize = table_size(th.td_lolen, th.td_flags);
	if (bsize < tsize)
	goto out;

	table = kvzalloc(tsize);
	if (table) {
	table->td_id = th.td_id;
	table->td_flags = th.td_flags;
	table->td_lolen = th.td_lolen;
	if (th.td_flags == YYTD_DATA8)
	UNPACK_ARRAY(table->td_data, blob, th.td_lolen,
	u8, u8, byte_to_byte);
	else if (th.td_flags == YYTD_DATA16)
	UNPACK_ARRAY(table->td_data, blob, th.td_lolen,
	u16, __be16, be16_to_cpu);
	else if (th.td_flags == YYTD_DATA32)
	UNPACK_ARRAY(table->td_data, blob, th.td_lolen,
	u32, __be32, be32_to_cpu);
	else
	goto fail;
	/* if table was vmalloced make sure the page tables are synced
	* before it is used, as it goes live to all cpus.
	*/
	if (is_vmalloc_addr(table))
	vm_unmap_aliases();
	}

	out:
	return table;
	fail:
	kvfree(table);
	return NULL;
	}

	/**
	* verify_dfa - verify that transitions and states in the tables are in bounds.
	* @dfa: dfa to test (NOT NULL)
	* @flags: flags controlling what type of accept table are acceptable
	*
	* Assumes dfa has gone through the first pass verification done by unpacking
	* NOTE: this does not valid accept table values
	*
	* Returns: %0 else error code on failure to verify
	*/
	static int verify_dfa(struct aa_dfa *dfa, int flags)
	{
	size_t i, state_count, trans_count;
	int error = -EPROTO;

	/* check that required tables exist */
	if (!(dfa->tables[YYTD_ID_DEF] &&
	dfa->tables[YYTD_ID_BASE] &&
	dfa->tables[YYTD_ID_NXT] && dfa->tables[YYTD_ID_CHK]))
	goto out;

	/* accept.size == default.size == base.size */
	state_count = dfa->tables[YYTD_ID_BASE]->td_lolen;
	if (ACCEPT1_FLAGS(flags)) {
	if (!dfa->tables[YYTD_ID_ACCEPT])
	goto out;
	if (state_count != dfa->tables[YYTD_ID_ACCEPT]->td_lolen)
	goto out;
	}
	if (ACCEPT2_FLAGS(flags)) {
	if (!dfa->tables[YYTD_ID_ACCEPT2])
	goto out;
	if (state_count != dfa->tables[YYTD_ID_ACCEPT2]->td_lolen)
	goto out;
	}
	if (state_count != dfa->tables[YYTD_ID_DEF]->td_lolen)
	goto out;

	/* next.size == chk.size */
	trans_count = dfa->tables[YYTD_ID_NXT]->td_lolen;
	if (trans_count != dfa->tables[YYTD_ID_CHK]->td_lolen)
	goto out;

	/* if equivalence classes then its table size must be 256 */
	if (dfa->tables[YYTD_ID_EC] &&
	dfa->tables[YYTD_ID_EC]->td_lolen != 256)
	goto out;

	if (flags & DFA_FLAG_VERIFY_STATES) {
	for (i = 0; i < state_count; i++) {
	if (DEFAULT_TABLE(dfa)[i] >= state_count)
	goto out;
	if (base_idx(BASE_TABLE(dfa)[i]) + 255 >= trans_count) {
	printk(KERN_ERR "AppArmor DFA next/check upper "
	"bounds error\n");
	goto out;
	}
	}

	for (i = 0; i < trans_count; i++) {
	if (NEXT_TABLE(dfa)[i] >= state_count)
	goto out;
	if (CHECK_TABLE(dfa)[i] >= state_count)
	goto out;
	}
	}

	error = 0;
	out:
	return error;
	}

	/**
	* dfa_free - free a dfa allocated by aa_dfa_unpack
	* @dfa: the dfa to free (MAYBE NULL)
	*
	* Requires: reference count to dfa == 0
	*/
	static void dfa_free(struct aa_dfa *dfa)
	{
	if (dfa) {
	int i;

	for (i = 0; i < ARRAY_SIZE(dfa->tables); i++) {
	kvfree(dfa->tables[i]);
	dfa->tables[i] = NULL;
	}
	kfree(dfa);
	}
	}

	/**
	* aa_dfa_free_kref - free aa_dfa by kref (called by aa_put_dfa)
	* @kr: kref callback for freeing of a dfa (NOT NULL)
	*/
	void aa_dfa_free_kref(struct kref *kref)
	{
	struct aa_dfa *dfa = container_of(kref, struct aa_dfa, count);
	dfa_free(dfa);
	}

	/**
	* aa_dfa_unpack - unpack the binary tables of a serialized dfa
	* @blob: aligned serialized stream of data to unpack (NOT NULL)
	* @size: size of data to unpack
	* @flags: flags controlling what type of accept tables are acceptable
	*
	* Unpack a dfa that has been serialized. To find information on the dfa
	* format look in Documentation/security/apparmor.txt
	* Assumes the dfa @blob stream has been aligned on a 8 byte boundary
	*
	* Returns: an unpacked dfa ready for matching or ERR_PTR on failure
	*/
	struct aa_dfa aa_dfa_unpack(void blob, size_t size, int flags)
	{
	int hsize;
	int error = -ENOMEM;
	char *data = blob;
	struct table_header *table = NULL;
	struct aa_dfa *dfa = kzalloc(sizeof(struct aa_dfa), GFP_KERNEL);
	if (!dfa)
	goto fail;

	kref_init(&dfa->count);

	error = -EPROTO;

	/* get dfa table set header */
	if (size < sizeof(struct table_set_header))
	goto fail;

	if (ntohl((__be32 ) data) != YYTH_MAGIC)
	goto fail;

	hsize = ntohl((__be32 ) (data + 4));
	if (size < hsize)
	goto fail;

	dfa->flags = ntohs((__be16 ) (data + 12));
	data += hsize;
	size -= hsize;

	while (size > 0) {
	table = unpack_table(data, size);
	if (!table)
	goto fail;

	switch (table->td_id) {
	case YYTD_ID_ACCEPT:
	if (!(table->td_flags & ACCEPT1_FLAGS(flags)))
	goto fail;
	break;
	case YYTD_ID_ACCEPT2:
	if (!(table->td_flags & ACCEPT2_FLAGS(flags)))
	goto fail;
	break;
	case YYTD_ID_BASE:
	if (table->td_flags != YYTD_DATA32)
	goto fail;
	break;
	case YYTD_ID_DEF:
	case YYTD_ID_NXT:
	case YYTD_ID_CHK:
	if (table->td_flags != YYTD_DATA16)
	goto fail;
	break;
	case YYTD_ID_EC:
	if (table->td_flags != YYTD_DATA8)
	goto fail;
	break;
	default:
	goto fail;
	}
	/* check for duplicate table entry */
	if (dfa->tables[table->td_id])
	goto fail;
	dfa->tables[table->td_id] = table;
	data += table_size(table->td_lolen, table->td_flags);
	size -= table_size(table->td_lolen, table->td_flags);
	table = NULL;
	}

	error = verify_dfa(dfa, flags);
	if (error)
	goto fail;

	return dfa;

	fail:
	kvfree(table);
	dfa_free(dfa);
	return ERR_PTR(error);
	}

	/**
	* aa_dfa_match_len - traverse @dfa to find state @str stops at
	* @dfa: the dfa to match @str against (NOT NULL)
	* @start: the state of the dfa to start matching in
	* @str: the string of bytes to match against the dfa (NOT NULL)
	* @len: length of the string of bytes to match
	*
	* aa_dfa_match_len will match @str against the dfa and return the state it
	* finished matching in. The final state can be used to look up the accepting
	* label, or as the start state of a continuing match.
	*
	* This function will happily match again the 0 byte and only finishes
	* when @len input is consumed.
	*
	* Returns: final state reached after input is consumed
	*/
	unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
	const char *str, int len)
	{
	u16 *def = DEFAULT_TABLE(dfa);
	u32 *base = BASE_TABLE(dfa);
	u16 *next = NEXT_TABLE(dfa);
	u16 *check = CHECK_TABLE(dfa);
	unsigned int state = start, pos;

	if (state == 0)
	return 0;

	/* current state is <state>, matching character str /
	if (dfa->tables[YYTD_ID_EC]) {
	/* Equivalence class table defined */
	u8 *equiv = EQUIV_TABLE(dfa);
	/* default is direct to next state */
	for (; len; len--) {
	pos = base_idx(base[state]) + equiv[(u8) *str++];
	if (check[pos] == state)
	state = next[pos];
	else
	state = def[state];
	}
	} else {
	/* default is direct to next state */
	for (; len; len--) {
	pos = base_idx(base[state]) + (u8) *str++;
	if (check[pos] == state)
	state = next[pos];
	else
	state = def[state];
	}
	}

	return state;
	}

	/**
	* aa_dfa_match - traverse @dfa to find state @str stops at
	* @dfa: the dfa to match @str against (NOT NULL)
	* @start: the state of the dfa to start matching in
	* @str: the null terminated string of bytes to match against the dfa (NOT NULL)
	*
	* aa_dfa_match will match @str against the dfa and return the state it
	* finished matching in. The final state can be used to look up the accepting
	* label, or as the start state of a continuing match.
	*
	* Returns: final state reached after input is consumed
	*/
	unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
	const char *str)
	{
	u16 *def = DEFAULT_TABLE(dfa);
	u32 *base = BASE_TABLE(dfa);
	u16 *next = NEXT_TABLE(dfa);
	u16 *check = CHECK_TABLE(dfa);
	unsigned int state = start, pos;

	if (state == 0)
	return 0;

	/* current state is <state>, matching character str /
	if (dfa->tables[YYTD_ID_EC]) {
	/* Equivalence class table defined */
	u8 *equiv = EQUIV_TABLE(dfa);
	/* default is direct to next state */
	while (*str) {
	pos = base_idx(base[state]) + equiv[(u8) *str++];
	if (check[pos] == state)
	state = next[pos];
	else
	state = def[state];
	}
	} else {
	/* default is direct to next state */
	while (*str) {
	pos = base_idx(base[state]) + (u8) *str++;
	if (check[pos] == state)
	state = next[pos];
	else
	state = def[state];
	}
	}

	return state;
	}

	/**
	* aa_dfa_next - step one character to the next state in the dfa
	* @dfa: the dfa to tranverse (NOT NULL)
	* @state: the state to start in
	* @c: the input character to transition on
	*
	* aa_dfa_match will step through the dfa by one input character @c
	*
	* Returns: state reach after input @c
	*/
	unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
	const char c)
	{
	u16 *def = DEFAULT_TABLE(dfa);
	u32 *base = BASE_TABLE(dfa);
	u16 *next = NEXT_TABLE(dfa);
	u16 *check = CHECK_TABLE(dfa);
	unsigned int pos;

	/* current state is <state>, matching character str /
	if (dfa->tables[YYTD_ID_EC]) {
	/* Equivalence class table defined */
	u8 *equiv = EQUIV_TABLE(dfa);
	/* default is direct to next state */

	pos = base_idx(base[state]) + equiv[(u8) c];
	if (check[pos] == state)
	state = next[pos];
	else
	state = def[state];
	} else {
	/* default is direct to next state */
	pos = base_idx(base[state]) + (u8) c;
	if (check[pos] == state)
	state = next[pos];
	else
	state = def[state];
	}

	return state;
	}