security/apparmor/include/match.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * AppArmor security module
   4  *
   5  * This file contains AppArmor policy dfa matching engine definitions.
   6  *
   7  * Copyright (C) 1998-2008 Novell/SUSE
   8  * Copyright 2009-2012 Canonical Ltd.
   9  */
  10
  11 #ifndef __AA_MATCH_H
  12 #define __AA_MATCH_H
  13
  14 #include <linux/kref.h>
  15
  16 #define DFA_NOMATCH                     0
  17 #define DFA_START                       1
  18
  19
  20 /**
  21  * The format used for transition tables is based on the GNU flex table
  22  * file format (--tables-file option; see Table File Format in the flex
  23  * info pages and the flex sources for documentation). The magic number
  24  * used in the header is 0x1B5E783D instead of 0xF13C57B1 though, because
  25  * new tables have been defined and others YY_ID_CHK (check) and YY_ID_DEF
  26  * (default) tables are used slightly differently (see the apparmor-parser
  27  * package).
  28  *
  29  *
  30  * The data in the packed dfa is stored in network byte order, and the tables
  31  * are arranged for flexibility.  We convert the table data to host native
  32  * byte order.
  33  *
  34  * The dfa begins with a table set header, and is followed by the actual
  35  * tables.
  36  */
  37
  38 #define YYTH_MAGIC      0x1B5E783D
  39 #define YYTH_FLAG_DIFF_ENCODE   1
  40
  41 struct table_set_header {
  42         u32 th_magic;           /* YYTH_MAGIC */
  43         u32 th_hsize;
  44         u32 th_ssize;
  45         u16 th_flags;
  46         char th_version[];
  47 };
  48
  49 /* The YYTD_ID are one less than flex table mappings.  The flex id
  50  * has 1 subtracted at table load time, this allows us to directly use the
  51  * ID's as indexes.
  52  */
  53 #define YYTD_ID_ACCEPT  0
  54 #define YYTD_ID_BASE    1
  55 #define YYTD_ID_CHK     2
  56 #define YYTD_ID_DEF     3
  57 #define YYTD_ID_EC      4
  58 #define YYTD_ID_META    5
  59 #define YYTD_ID_ACCEPT2 6
  60 #define YYTD_ID_NXT     7
  61 #define YYTD_ID_TSIZE   8
  62 #define YYTD_ID_MAX     8
  63
  64 #define YYTD_DATA8      1
  65 #define YYTD_DATA16     2
  66 #define YYTD_DATA32     4
  67 #define YYTD_DATA64     8
  68
  69 /* ACCEPT & ACCEPT2 tables gets 6 dedicated flags, YYTD_DATAX define the
  70  * first flags
  71  */
  72 #define ACCEPT1_FLAGS(X) ((X) & 0x3f)
  73 #define ACCEPT2_FLAGS(X) ACCEPT1_FLAGS((X) >> YYTD_ID_ACCEPT2)
  74 #define TO_ACCEPT1_FLAG(X) ACCEPT1_FLAGS(X)
  75 #define TO_ACCEPT2_FLAG(X) (ACCEPT1_FLAGS(X) << YYTD_ID_ACCEPT2)
  76 #define DFA_FLAG_VERIFY_STATES 0x1000
  77
  78 struct table_header {
  79         u16 td_id;
  80         u16 td_flags;
  81         u32 td_hilen;
  82         u32 td_lolen;
  83         char td_data[];
  84 };
  85
  86 #define DEFAULT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_DEF]->td_data))
  87 #define BASE_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_BASE]->td_data))
  88 #define NEXT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_NXT]->td_data))
  89 #define CHECK_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_CHK]->td_data))
  90 #define EQUIV_TABLE(DFA) ((u8 *)((DFA)->tables[YYTD_ID_EC]->td_data))
  91 #define ACCEPT_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT]->td_data))
  92 #define ACCEPT_TABLE2(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT2]->td_data))
  93
  94 struct aa_dfa {
  95         struct kref count;
  96         u16 flags;
  97         struct table_header *tables[YYTD_ID_TSIZE];
  98 };
  99
 100 extern struct aa_dfa *nulldfa;
 101 extern struct aa_dfa *stacksplitdfa;
 102
 103 #define byte_to_byte(X) (X)
 104
 105 #define UNPACK_ARRAY(TABLE, BLOB, LEN, TTYPE, BTYPE, NTOHX)     \
 106         do { \
 107                 typeof(LEN) __i; \
 108                 TTYPE *__t = (TTYPE *) TABLE; \
 109                 BTYPE *__b = (BTYPE *) BLOB; \
 110                 for (__i = 0; __i < LEN; __i++) { \
 111                         __t[__i] = NTOHX(__b[__i]); \
 112                 } \
 113         } while (0)
 114
 115 static inline size_t table_size(size_t len, size_t el_size)
 116 {
 117         return ALIGN(sizeof(struct table_header) + len * el_size, 8);
 118 }
 119
 120 int aa_setup_dfa_engine(void);
 121 void aa_teardown_dfa_engine(void);
 122
 123 struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags);
 124 unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
 125                               const char *str, int len);
 126 unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
 127                           const char *str);
 128 unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
 129                          const char c);
 130 unsigned int aa_dfa_match_until(struct aa_dfa *dfa, unsigned int start,
 131                                 const char *str, const char **retpos);
 132 unsigned int aa_dfa_matchn_until(struct aa_dfa *dfa, unsigned int start,
 133                                  const char *str, int n, const char **retpos);
 134
 135 void aa_dfa_free_kref(struct kref *kref);
 136
 137 #define WB_HISTORY_SIZE 8
 138 struct match_workbuf {
 139         unsigned int count;
 140         unsigned int pos;
 141         unsigned int len;
 142         unsigned int size;      /* power of 2, same as history size */
 143         unsigned int history[WB_HISTORY_SIZE];
 144 };
 145 #define DEFINE_MATCH_WB(N)              \
 146 struct match_workbuf N = {              \
 147         .count = 0,                     \
 148         .pos = 0,                       \
 149         .len = 0,                       \
 150         .size = WB_HISTORY_SIZE,                        \
 151 }
 152
 153 unsigned int aa_dfa_leftmatch(struct aa_dfa *dfa, unsigned int start,
 154                               const char *str, unsigned int *count);
 155
 156 /**
 157  * aa_get_dfa - increment refcount on dfa @p
 158  * @dfa: dfa  (MAYBE NULL)
 159  *
 160  * Returns: pointer to @dfa if @dfa is NULL will return NULL
 161  * Requires: @dfa must be held with valid refcount when called
 162  */
 163 static inline struct aa_dfa *aa_get_dfa(struct aa_dfa *dfa)
 164 {
 165         if (dfa)
 166                 kref_get(&(dfa->count));
 167
 168         return dfa;
 169 }
 170
 171 /**
 172  * aa_put_dfa - put a dfa refcount
 173  * @dfa: dfa to put refcount   (MAYBE NULL)
 174  *
 175  * Requires: if @dfa != NULL that a valid refcount be held
 176  */
 177 static inline void aa_put_dfa(struct aa_dfa *dfa)
 178 {
 179         if (dfa)
 180                 kref_put(&dfa->count, aa_dfa_free_kref);
 181 }
 182
 183 #define MATCH_FLAG_DIFF_ENCODE 0x80000000
 184 #define MARK_DIFF_ENCODE 0x40000000
 185
 186 #endif /* __AA_MATCH_H */