/* * AppArmor security module * * This file contains AppArmor dfa based regular expression matching engine * * Copyright (C) 1998-2008 Novell/SUSE * Copyright 2009-2010 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/apparmor.h"#include "include/match.h" /** * 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 kmalloc) */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(*(u16 *) (blob)) - 1;	th.td_flags = be16_to_cpu(*(u16 *) (blob + 2));	th.td_lolen = be32_to_cpu(*(u32 *) (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 = kvmalloc(tsize);	if (table) {		*table = th;		if (th.td_flags == YYTD_DATA8)			UNPACK_ARRAY(table->td_data, blob, th.td_lolen,				     u8, byte_to_byte);		else if (th.td_flags == YYTD_DATA16)			UNPACK_ARRAY(table->td_data, blob, th.td_lolen,				     u16, be16_to_cpu);		else if (th.td_flags == YYTD_DATA32)			UNPACK_ARRAY(table->td_data, blob, th.td_lolen,				     u32, be32_to_cpu);		else			goto fail;	} out:	/* 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();	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;			/* TODO: do check that DEF state recursion terminates */			if (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(*(u32 *) data) != YYTH_MAGIC)		goto fail; 	hsize = ntohl(*(u32 *) (data + 4));	if (size < hsize)		goto fail; 	dfa->flags = ntohs(*(u16 *) (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[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[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[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[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[state] + equiv[(u8) c];		if (check[pos] == state)			state = next[pos];		else			state = def[state];	} else {		/* default is direct to next state */		pos = base[state] + (u8) c;		if (check[pos] == state)			state = next[pos];		else			state = def[state];	} 	return state;}