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 #define YYTH_FLAG_DIFF_ENCODE   1
  44
  45 struct table_set_header {
  46         u32 th_magic;           /* YYTH_MAGIC */
  47         u32 th_hsize;
  48         u32 th_ssize;
  49         u16 th_flags;
  50         char th_version[];
  51 };
  52
  53 /* The YYTD_ID are one less than flex table mappings.  The flex id
  54  * has 1 subtracted at table load time, this allows us to directly use the
  55  * ID's as indexes.
  56  */
  57 #define YYTD_ID_ACCEPT  0
  58 #define YYTD_ID_BASE    1
  59 #define YYTD_ID_CHK     2
  60 #define YYTD_ID_DEF     3
  61 #define YYTD_ID_EC      4
  62 #define YYTD_ID_META    5
  63 #define YYTD_ID_ACCEPT2 6
  64 #define YYTD_ID_NXT     7
  65 #define YYTD_ID_TSIZE   8
  66 #define YYTD_ID_MAX     8
  67
  68 #define YYTD_DATA8      1
  69 #define YYTD_DATA16     2
  70 #define YYTD_DATA32     4
  71 #define YYTD_DATA64     8
  72
  73 /* ACCEPT & ACCEPT2 tables gets 6 dedicated flags, YYTD_DATAX define the
  74  * first flags
  75  */
  76 #define ACCEPT1_FLAGS(X) ((X) & 0x3f)
  77 #define ACCEPT2_FLAGS(X) ACCEPT1_FLAGS((X) >> YYTD_ID_ACCEPT2)
  78 #define TO_ACCEPT1_FLAG(X) ACCEPT1_FLAGS(X)
  79 #define TO_ACCEPT2_FLAG(X) (ACCEPT1_FLAGS(X) << YYTD_ID_ACCEPT2)
  80 #define DFA_FLAG_VERIFY_STATES 0x1000
  81
  82 struct table_header {
  83         u16 td_id;
  84         u16 td_flags;
  85         u32 td_hilen;
  86         u32 td_lolen;
  87         char td_data[];
  88 };
  89
  90 #define DEFAULT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_DEF]->td_data))
  91 #define BASE_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_BASE]->td_data))
  92 #define NEXT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_NXT]->td_data))
  93 #define CHECK_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_CHK]->td_data))
  94 #define EQUIV_TABLE(DFA) ((u8 *)((DFA)->tables[YYTD_ID_EC]->td_data))
  95 #define ACCEPT_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT]->td_data))
  96 #define ACCEPT_TABLE2(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT2]->td_data))
  97
  98 struct aa_dfa {
  99         struct kref count;
 100         u16 flags;
 101         struct table_header *tables[YYTD_ID_TSIZE];
 102 };
 103
 104 extern struct aa_dfa *nulldfa;
 105 extern struct aa_dfa *stacksplitdfa;
 106
 107 #define byte_to_byte(X) (X)
 108
 109 #define UNPACK_ARRAY(TABLE, BLOB, LEN, TTYPE, BTYPE, NTOHX)     \
 110         do { \
 111                 typeof(LEN) __i; \
 112                 TTYPE *__t = (TTYPE *) TABLE; \
 113                 BTYPE *__b = (BTYPE *) BLOB; \
 114                 for (__i = 0; __i < LEN; __i++) { \
 115                         __t[__i] = NTOHX(__b[__i]); \
 116                 } \
 117         } while (0)
 118
 119 static inline size_t table_size(size_t len, size_t el_size)
 120 {
 121         return ALIGN(sizeof(struct table_header) + len * el_size, 8);
 122 }
 123
 124 int aa_setup_dfa_engine(void);
 125 void aa_teardown_dfa_engine(void);
 126
 127 struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags);
 128 unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
 129                               const char *str, int len);
 130 unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
 131                           const char *str);
 132 unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
 133                          const char c);
 134 unsigned int aa_dfa_match_until(struct aa_dfa *dfa, unsigned int start,
 135                                 const char *str, const char **retpos);
 136 unsigned int aa_dfa_matchn_until(struct aa_dfa *dfa, unsigned int start,
 137                                  const char *str, int n, const char **retpos);
 138
 139 void aa_dfa_free_kref(struct kref *kref);
 140
 141 #define WB_HISTORY_SIZE 8
 142 struct match_workbuf {
 143         unsigned int count;
 144         unsigned int pos;
 145         unsigned int len;
 146         unsigned int size;      /* power of 2, same as history size */
 147         unsigned int history[WB_HISTORY_SIZE];
 148 };
 149 #define DEFINE_MATCH_WB(N)              \
 150 struct match_workbuf N = {              \
 151         .count = 0,                     \
 152         .pos = 0,                       \
 153         .len = 0,                       \
 154         .size = WB_HISTORY_SIZE,                        \
 155 }
 156
 157 unsigned int aa_dfa_leftmatch(struct aa_dfa *dfa, unsigned int start,
 158                               const char *str, unsigned int *count);
 159
 160 /**
 161  * aa_get_dfa - increment refcount on dfa @p
 162  * @dfa: dfa  (MAYBE NULL)
 163  *
 164  * Returns: pointer to @dfa if @dfa is NULL will return NULL
 165  * Requires: @dfa must be held with valid refcount when called
 166  */
 167 static inline struct aa_dfa *aa_get_dfa(struct aa_dfa *dfa)
 168 {
 169         if (dfa)
 170                 kref_get(&(dfa->count));
 171
 172         return dfa;
 173 }
 174
 175 /**
 176  * aa_put_dfa - put a dfa refcount
 177  * @dfa: dfa to put refcount   (MAYBE NULL)
 178  *
 179  * Requires: if @dfa != NULL that a valid refcount be held
 180  */
 181 static inline void aa_put_dfa(struct aa_dfa *dfa)
 182 {
 183         if (dfa)
 184                 kref_put(&dfa->count, aa_dfa_free_kref);
 185 }
 186
 187 #define MATCH_FLAG_DIFF_ENCODE 0x80000000
 188 #define MARK_DIFF_ENCODE 0x40000000
 189
 190 #endif /* __AA_MATCH_H */