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
  44 struct 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
  80 struct 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
  96 struct 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
 114 static 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
 119 struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags);
 120 unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
 121                               const char *str, int len);
 122 unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
 123                           const char *str);
 124 unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
 125                          const char c);
 126
 127 void 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  */
 135 static 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 */