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/*
* AppArmor security module
*
* This file contains AppArmor policy dfa matching engine definitions.
*
* 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.
*/
#ifndef __AA_MATCH_H
#define __AA_MATCH_H
#include <linux/kref.h>
#define DFA_NOMATCH 0
#define DFA_START 1
/**
* The format used for transition tables is based on the GNU flex table
* file format (--tables-file option; see Table File Format in the flex
* info pages and the flex sources for documentation). The magic number
* used in the header is 0x1B5E783D instead of 0xF13C57B1 though, because
* new tables have been defined and others YY_ID_CHK (check) and YY_ID_DEF
* (default) tables are used slightly differently (see the apparmor-parser
* package).
*
*
* The data in the packed dfa is stored in network byte order, and the tables
* are arranged for flexibility. We convert the table data to host native
* byte order.
*
* The dfa begins with a table set header, and is followed by the actual
* tables.
*/
#define YYTH_MAGIC 0x1B5E783D
struct table_set_header {
u32 th_magic; /* YYTH_MAGIC */
u32 th_hsize;
u32 th_ssize;
u16 th_flags;
char th_version[];
};
/* The YYTD_ID are one less than flex table mappings. The flex id
* has 1 subtracted at table load time, this allows us to directly use the
* ID's as indexes.
*/
#define YYTD_ID_ACCEPT 0
#define YYTD_ID_BASE 1
#define YYTD_ID_CHK 2
#define YYTD_ID_DEF 3
#define YYTD_ID_EC 4
#define YYTD_ID_META 5
#define YYTD_ID_ACCEPT2 6
#define YYTD_ID_NXT 7
#define YYTD_ID_TSIZE 8
#define YYTD_ID_MAX 8
#define YYTD_DATA8 1
#define YYTD_DATA16 2
#define YYTD_DATA32 4
#define YYTD_DATA64 8
/* ACCEPT & ACCEPT2 tables gets 6 dedicated flags, YYTD_DATAX define the
* first flags
*/
#define ACCEPT1_FLAGS(X) ((X) & 0x3f)
#define ACCEPT2_FLAGS(X) ACCEPT1_FLAGS((X) >> YYTD_ID_ACCEPT2)
#define TO_ACCEPT1_FLAG(X) ACCEPT1_FLAGS(X)
#define TO_ACCEPT2_FLAG(X) (ACCEPT1_FLAGS(X) << YYTD_ID_ACCEPT2)
#define DFA_FLAG_VERIFY_STATES 0x1000
struct table_header {
u16 td_id;
u16 td_flags;
u32 td_hilen;
u32 td_lolen;
char td_data[];
};
#define DEFAULT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_DEF]->td_data))
#define BASE_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_BASE]->td_data))
#define NEXT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_NXT]->td_data))
#define CHECK_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_CHK]->td_data))
#define EQUIV_TABLE(DFA) ((u8 *)((DFA)->tables[YYTD_ID_EC]->td_data))
#define ACCEPT_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT]->td_data))
#define ACCEPT_TABLE2(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT2]->td_data))
struct aa_dfa {
struct kref count;
u16 flags;
struct table_header *tables[YYTD_ID_TSIZE];
};
extern struct aa_dfa *nulldfa;
#define byte_to_byte(X) (X)
#define UNPACK_ARRAY(TABLE, BLOB, LEN, TYPE, NTOHX) \
do { \
typeof(LEN) __i; \
TYPE *__t = (TYPE *) TABLE; \
TYPE *__b = (TYPE *) BLOB; \
for (__i = 0; __i < LEN; __i++) { \
__t[__i] = NTOHX(__b[__i]); \
} \
} while (0)
static inline size_t table_size(size_t len, size_t el_size)
{
return ALIGN(sizeof(struct table_header) + len * el_size, 8);
}
int aa_setup_dfa_engine(void);
void aa_teardown_dfa_engine(void);
struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags);
unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
const char *str, int len);
unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
const char *str);
unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
const char c);
void aa_dfa_free_kref(struct kref *kref);
/**
* aa_get_dfa - increment refcount on dfa @p
* @dfa: dfa (MAYBE NULL)
*
* Returns: pointer to @dfa if @dfa is NULL will return NULL
* Requires: @dfa must be held with valid refcount when called
*/
static inline struct aa_dfa *aa_get_dfa(struct aa_dfa *dfa)
{
if (dfa)
kref_get(&(dfa->count));
return dfa;
}
/**
* aa_put_dfa - put a dfa refcount
* @dfa: dfa to put refcount (MAYBE NULL)
*
* Requires: if @dfa != NULL that a valid refcount be held
*/
static inline void aa_put_dfa(struct aa_dfa *dfa)
{
if (dfa)
kref_put(&dfa->count, aa_dfa_free_kref);
}
#endif /* __AA_MATCH_H */
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