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 #define YYTH_FLAG_OOB_TRANS     2
  41 #define YYTH_FLAGS (YYTH_FLAG_DIFF_ENCODE | YYTH_FLAG_OOB_TRANS)
  42
  43 #define MAX_OOB_SUPPORTED       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         u32 max_oob;
 102         struct table_header *tables[YYTD_ID_TSIZE];
 103 };
 104
 105 extern struct aa_dfa *nulldfa;
 106 extern struct aa_dfa *stacksplitdfa;
 107
 108 #define byte_to_byte(X) (X)
 109
 110 #define UNPACK_ARRAY(TABLE, BLOB, LEN, TTYPE, BTYPE, NTOHX)     \
 111         do { \
 112                 typeof(LEN) __i; \
 113                 TTYPE *__t = (TTYPE *) TABLE; \
 114                 BTYPE *__b = (BTYPE *) BLOB; \
 115                 for (__i = 0; __i < LEN; __i++) { \
 116                         __t[__i] = NTOHX(__b[__i]); \
 117                 } \
 118         } while (0)
 119
 120 static inline size_t table_size(size_t len, size_t el_size)
 121 {
 122         return ALIGN(sizeof(struct table_header) + len * el_size, 8);
 123 }
 124
 125 int aa_setup_dfa_engine(void);
 126 void aa_teardown_dfa_engine(void);
 127
 128 struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags);
 129 unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
 130                               const char *str, int len);
 131 unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
 132                           const char *str);
 133 unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
 134                          const char c);
 135 unsigned int aa_dfa_outofband_transition(struct aa_dfa *dfa,
 136                                          unsigned int state);
 137 unsigned int aa_dfa_match_until(struct aa_dfa *dfa, unsigned int start,
 138                                 const char *str, const char **retpos);
 139 unsigned int aa_dfa_matchn_until(struct aa_dfa *dfa, unsigned int start,
 140                                  const char *str, int n, const char **retpos);
 141
 142 void aa_dfa_free_kref(struct kref *kref);
 143
 144 #define WB_HISTORY_SIZE 24
 145 struct match_workbuf {
 146         unsigned int count;
 147         unsigned int pos;
 148         unsigned int len;
 149         unsigned int size;      /* power of 2, same as history size */
 150         unsigned int history[WB_HISTORY_SIZE];
 151 };
 152 #define DEFINE_MATCH_WB(N)              \
 153 struct match_workbuf N = {              \
 154         .count = 0,                     \
 155         .pos = 0,                       \
 156         .len = 0,                       \
 157 }
 158
 159 unsigned int aa_dfa_leftmatch(struct aa_dfa *dfa, unsigned int start,
 160                               const char *str, unsigned int *count);
 161
 162 /**
 163  * aa_get_dfa - increment refcount on dfa @p
 164  * @dfa: dfa  (MAYBE NULL)
 165  *
 166  * Returns: pointer to @dfa if @dfa is NULL will return NULL
 167  * Requires: @dfa must be held with valid refcount when called
 168  */
 169 static inline struct aa_dfa *aa_get_dfa(struct aa_dfa *dfa)
 170 {
 171         if (dfa)
 172                 kref_get(&(dfa->count));
 173
 174         return dfa;
 175 }
 176
 177 /**
 178  * aa_put_dfa - put a dfa refcount
 179  * @dfa: dfa to put refcount   (MAYBE NULL)
 180  *
 181  * Requires: if @dfa != NULL that a valid refcount be held
 182  */
 183 static inline void aa_put_dfa(struct aa_dfa *dfa)
 184 {
 185         if (dfa)
 186                 kref_put(&dfa->count, aa_dfa_free_kref);
 187 }
 188
 189 #define MATCH_FLAG_DIFF_ENCODE 0x80000000
 190 #define MARK_DIFF_ENCODE 0x40000000
 191 #define MATCH_FLAG_OOB_TRANSITION 0x20000000
 192 #define MATCH_FLAGS_MASK 0xff000000
 193 #define MATCH_FLAGS_VALID (MATCH_FLAG_DIFF_ENCODE | MATCH_FLAG_OOB_TRANSITION)
 194 #define MATCH_FLAGS_INVALID (MATCH_FLAGS_MASK & ~MATCH_FLAGS_VALID)
 195
 196 #endif /* __AA_MATCH_H */