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 #define YYTD_ID_MAX     8
  66
  67 #define YYTD_DATA8      1
  68 #define YYTD_DATA16     2
  69 #define YYTD_DATA32     4
  70 #define YYTD_DATA64     8
  71
  72 /* ACCEPT & ACCEPT2 tables gets 6 dedicated flags, YYTD_DATAX define the
  73  * first flags
  74  */
  75 #define ACCEPT1_FLAGS(X) ((X) & 0x3f)
  76 #define ACCEPT2_FLAGS(X) ACCEPT1_FLAGS((X) >> YYTD_ID_ACCEPT2)
  77 #define TO_ACCEPT1_FLAG(X) ACCEPT1_FLAGS(X)
  78 #define TO_ACCEPT2_FLAG(X) (ACCEPT1_FLAGS(X) << YYTD_ID_ACCEPT2)
  79 #define DFA_FLAG_VERIFY_STATES 0x1000
  80
  81 struct table_header {
  82         u16 td_id;
  83         u16 td_flags;
  84         u32 td_hilen;
  85         u32 td_lolen;
  86         char td_data[];
  87 };
  88
  89 #define DEFAULT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_DEF]->td_data))
  90 #define BASE_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_BASE]->td_data))
  91 #define NEXT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_NXT]->td_data))
  92 #define CHECK_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_CHK]->td_data))
  93 #define EQUIV_TABLE(DFA) ((u8 *)((DFA)->tables[YYTD_ID_EC]->td_data))
  94 #define ACCEPT_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT]->td_data))
  95 #define ACCEPT_TABLE2(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT2]->td_data))
  96
  97 struct aa_dfa {
  98         struct kref count;
  99         u16 flags;
 100         struct table_header *tables[YYTD_ID_TSIZE];
 101 };
 102
 103 extern struct aa_dfa *nulldfa;
 104
 105 #define byte_to_byte(X) (X)
 106
 107 #define UNPACK_ARRAY(TABLE, BLOB, LEN, TTYPE, BTYPE, NTOHX)     \
 108         do { \
 109                 typeof(LEN) __i; \
 110                 TTYPE *__t = (TTYPE *) TABLE; \
 111                 BTYPE *__b = (BTYPE *) BLOB; \
 112                 for (__i = 0; __i < LEN; __i++) { \
 113                         __t[__i] = NTOHX(__b[__i]); \
 114                 } \
 115         } while (0)
 116
 117 static inline size_t table_size(size_t len, size_t el_size)
 118 {
 119         return ALIGN(sizeof(struct table_header) + len * el_size, 8);
 120 }
 121
 122 int aa_setup_dfa_engine(void);
 123 void aa_teardown_dfa_engine(void);
 124
 125 struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags);
 126 unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
 127                               const char *str, int len);
 128 unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
 129                           const char *str);
 130 unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
 131                          const char c);
 132
 133 void aa_dfa_free_kref(struct kref *kref);
 134
 135 /**
 136  * aa_get_dfa - increment refcount on dfa @p
 137  * @dfa: dfa  (MAYBE NULL)
 138  *
 139  * Returns: pointer to @dfa if @dfa is NULL will return NULL
 140  * Requires: @dfa must be held with valid refcount when called
 141  */
 142 static inline struct aa_dfa *aa_get_dfa(struct aa_dfa *dfa)
 143 {
 144         if (dfa)
 145                 kref_get(&(dfa->count));
 146
 147         return dfa;
 148 }
 149
 150 /**
 151  * aa_put_dfa - put a dfa refcount
 152  * @dfa: dfa to put refcount   (MAYBE NULL)
 153  *
 154  * Requires: if @dfa != NULL that a valid refcount be held
 155  */
 156 static inline void aa_put_dfa(struct aa_dfa *dfa)
 157 {
 158         if (dfa)
 159                 kref_put(&dfa->count, aa_dfa_free_kref);
 160 }
 161
 162 #endif /* __AA_MATCH_H */