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 2009-2010 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 #include <linux/workqueue.h>
  20
  21 #define DFA_NOMATCH                     0
  22 #define DFA_START                       1
  23
  24 #define DFA_VALID_PERM_MASK             0xffffffff
  25 #define DFA_VALID_PERM2_MASK            0xffffffff
  26
  27 /**
  28  * The format used for transition tables is based on the GNU flex table
  29  * file format (--tables-file option; see Table File Format in the flex
  30  * info pages and the flex sources for documentation). The magic number
  31  * used in the header is 0x1B5E783D instead of 0xF13C57B1 though, because
  32  * the YY_ID_CHK (check) and YY_ID_DEF (default) tables are used
  33  * slightly differently (see the apparmor-parser package).
  34  */
  35
  36 #define YYTH_MAGIC      0x1B5E783D
  37 #define YYTH_DEF_RECURSE 0x1                    /* DEF Table is recursive */
  38
  39 struct table_set_header {
  40         u32 th_magic;           /* YYTH_MAGIC */
  41         u32 th_hsize;
  42         u32 th_ssize;
  43         u16 th_flags;
  44         char th_version[];
  45 };
  46
  47 /* The YYTD_ID are one less than flex table mappings.  The flex id
  48  * has 1 subtracted at table load time, this allows us to directly use the
  49  * ID's as indexes.
  50  */
  51 #define YYTD_ID_ACCEPT  0
  52 #define YYTD_ID_BASE    1
  53 #define YYTD_ID_CHK     2
  54 #define YYTD_ID_DEF     3
  55 #define YYTD_ID_EC      4
  56 #define YYTD_ID_META    5
  57 #define YYTD_ID_ACCEPT2 6
  58 #define YYTD_ID_NXT     7
  59 #define YYTD_ID_TSIZE   8
  60
  61 #define YYTD_DATA8      1
  62 #define YYTD_DATA16     2
  63 #define YYTD_DATA32     4
  64 #define YYTD_DATA64     8
  65
  66 /* Each ACCEPT2 table gets 6 dedicated flags, YYTD_DATAX define the
  67  * first flags
  68  */
  69 #define ACCEPT1_FLAGS(X) ((X) & 0x3f)
  70 #define ACCEPT2_FLAGS(X) ACCEPT1_FLAGS((X) >> YYTD_ID_ACCEPT2)
  71 #define TO_ACCEPT1_FLAG(X) ACCEPT1_FLAGS(X)
  72 #define TO_ACCEPT2_FLAG(X) (ACCEPT1_FLAGS(X) << YYTD_ID_ACCEPT2)
  73 #define DFA_FLAG_VERIFY_STATES 0x1000
  74
  75 struct table_header {
  76         u16 td_id;
  77         u16 td_flags;
  78         u32 td_hilen;
  79         u32 td_lolen;
  80         char td_data[];
  81 };
  82
  83 #define DEFAULT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_DEF]->td_data))
  84 #define BASE_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_BASE]->td_data))
  85 #define NEXT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_NXT]->td_data))
  86 #define CHECK_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_CHK]->td_data))
  87 #define EQUIV_TABLE(DFA) ((u8 *)((DFA)->tables[YYTD_ID_EC]->td_data))
  88 #define ACCEPT_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT]->td_data))
  89 #define ACCEPT_TABLE2(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT2]->td_data))
  90
  91 struct aa_dfa {
  92         struct kref count;
  93         u16 flags;
  94         struct table_header *tables[YYTD_ID_TSIZE];
  95 };
  96
  97 #define byte_to_byte(X) (X)
  98
  99 #define UNPACK_ARRAY(TABLE, BLOB, LEN, TYPE, NTOHX) \
 100         do { \
 101                 typeof(LEN) __i; \
 102                 TYPE *__t = (TYPE *) TABLE; \
 103                 TYPE *__b = (TYPE *) BLOB; \
 104                 for (__i = 0; __i < LEN; __i++) { \
 105                         __t[__i] = NTOHX(__b[__i]); \
 106                 } \
 107         } while (0)
 108
 109 static inline size_t table_size(size_t len, size_t el_size)
 110 {
 111         return ALIGN(sizeof(struct table_header) + len * el_size, 8);
 112 }
 113
 114 struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags);
 115 unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
 116                               const char *str, int len);
 117 unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
 118                           const char *str);
 119 unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
 120                          const char c);
 121
 122 void aa_dfa_free_kref(struct kref *kref);
 123
 124 /**
 125  * aa_put_dfa - put a dfa refcount
 126  * @dfa: dfa to put refcount   (MAYBE NULL)
 127  *
 128  * Requires: if @dfa != NULL that a valid refcount be held
 129  */
 130 static inline void aa_put_dfa(struct aa_dfa *dfa)
 131 {
 132         if (dfa)
 133                 kref_put(&dfa->count, aa_dfa_free_kref);
 134 }
 135
 136 #endif /* __AA_MATCH_H */