LXR linux/security/apparmor/include/match.h

   1/*
   2 * AppArmor security module
   3 *
   4 * This file contains AppArmor policy dfa matching engine definitions.
   5 *
   6 * Copyright (C) 1998-2008 Novell/SUSE
   7 * Copyright 2009-2012 Canonical Ltd.
   8 *
   9 * This program is free software; you can redistribute it and/or
  10 * modify it under the terms of the GNU General Public License as
  11 * published by the Free Software Foundation, version 2 of the
  12 * License.
  13 */
  14
  15#ifndef __AA_MATCH_H
  16#define __AA_MATCH_H
  17
  18#include <linux/kref.h>
  19
  20#define DFA_NOMATCH                     0
  21#define DFA_START                       1
  22
  23
  24/**
  25 * The format used for transition tables is based on the GNU flex table
  26 * file format (--tables-file option; see Table File Format in the flex
  27 * info pages and the flex sources for documentation). The magic number
  28 * used in the header is 0x1B5E783D instead of 0xF13C57B1 though, because
  29 * new tables have been defined and others YY_ID_CHK (check) and YY_ID_DEF
  30 * (default) tables are used slightly differently (see the apparmor-parser
  31 * package).
  32 *
  33 *
  34 * The data in the packed dfa is stored in network byte order, and the tables
  35 * are arranged for flexibility.  We convert the table data to host native
  36 * byte order.
  37 *
  38 * The dfa begins with a table set header, and is followed by the actual
  39 * tables.
  40 */
  41
  42#define YYTH_MAGIC      0x1B5E783D
  43
  44struct table_set_header {
  45        u32 th_magic;           /* YYTH_MAGIC */
  46        u32 th_hsize;
  47        u32 th_ssize;
  48        u16 th_flags;
  49        char th_version[];
  50};
  51
  52/* The YYTD_ID are one less than flex table mappings.  The flex id
  53 * has 1 subtracted at table load time, this allows us to directly use the
  54 * ID's as indexes.
  55 */
  56#define YYTD_ID_ACCEPT  0
  57#define YYTD_ID_BASE    1
  58#define YYTD_ID_CHK     2
  59#define YYTD_ID_DEF     3
  60#define YYTD_ID_EC      4
  61#define YYTD_ID_META    5
  62#define YYTD_ID_ACCEPT2 6
  63#define YYTD_ID_NXT     7
  64#define YYTD_ID_TSIZE   8
  65
  66#define YYTD_DATA8      1
  67#define YYTD_DATA16     2
  68#define YYTD_DATA32     4
  69#define YYTD_DATA64     8
  70
  71/* ACCEPT & ACCEPT2 tables gets 6 dedicated flags, YYTD_DATAX define the
  72 * first flags
  73 */
  74#define ACCEPT1_FLAGS(X) ((X) & 0x3f)
  75#define ACCEPT2_FLAGS(X) ACCEPT1_FLAGS((X) >> YYTD_ID_ACCEPT2)
  76#define TO_ACCEPT1_FLAG(X) ACCEPT1_FLAGS(X)
  77#define TO_ACCEPT2_FLAG(X) (ACCEPT1_FLAGS(X) << YYTD_ID_ACCEPT2)
  78#define DFA_FLAG_VERIFY_STATES 0x1000
  79
  80struct table_header {
  81        u16 td_id;
  82        u16 td_flags;
  83        u32 td_hilen;
  84        u32 td_lolen;
  85        char td_data[];
  86};
  87
  88#define DEFAULT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_DEF]->td_data))
  89#define BASE_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_BASE]->td_data))
  90#define NEXT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_NXT]->td_data))
  91#define CHECK_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_CHK]->td_data))
  92#define EQUIV_TABLE(DFA) ((u8 *)((DFA)->tables[YYTD_ID_EC]->td_data))
  93#define ACCEPT_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT]->td_data))
  94#define ACCEPT_TABLE2(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT2]->td_data))
  95
  96struct aa_dfa {
  97        struct kref count;
  98        u16 flags;
  99        struct table_header *tables[YYTD_ID_TSIZE];
 100};
 101
 102#define byte_to_byte(X) (X)
 103
 104#define UNPACK_ARRAY(TABLE, BLOB, LEN, TYPE, NTOHX) \
 105        do { \
 106                typeof(LEN) __i; \
 107                TYPE *__t = (TYPE *) TABLE; \
 108                TYPE *__b = (TYPE *) BLOB; \
 109                for (__i = 0; __i < LEN; __i++) { \
 110                        __t[__i] = NTOHX(__b[__i]); \
 111                } \
 112        } while (0)
 113
 114static inline size_t table_size(size_t len, size_t el_size)
 115{
 116        return ALIGN(sizeof(struct table_header) + len * el_size, 8);
 117}
 118
 119struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags);
 120unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
 121                              const char *str, int len);
 122unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
 123                          const char *str);
 124unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
 125                         const char c);
 126
 127void aa_dfa_free_kref(struct kref *kref);
 128
 129/**
 130 * aa_put_dfa - put a dfa refcount
 131 * @dfa: dfa to put refcount   (MAYBE NULL)
 132 *
 133 * Requires: if @dfa != NULL that a valid refcount be held
 134 */
 135static inline void aa_put_dfa(struct aa_dfa *dfa)
 136{
 137        if (dfa)
 138                kref_put(&dfa->count, aa_dfa_free_kref);
 139}
 140
 141#endif /* __AA_MATCH_H */
 142