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 #include <linux/overflow.h> 16 17 #define DFA_NOMATCH 0 18 #define DFA_START 1 19 20 21 /* 22 * The format used for transition tables is based on the GNU flex table 23 * file format (--tables-file option; see Table File Format in the flex 24 * info pages and the flex sources for documentation). The magic number 25 * used in the header is 0x1B5E783D instead of 0xF13C57B1 though, because 26 * new tables have been defined and others YY_ID_CHK (check) and YY_ID_DEF 27 * (default) tables are used slightly differently (see the apparmor-parser 28 * package). 29 * 30 * 31 * The data in the packed dfa is stored in network byte order, and the tables 32 * are arranged for flexibility. We convert the table data to host native 33 * byte order. 34 * 35 * The dfa begins with a table set header, and is followed by the actual 36 * tables. 37 */ 38 39 #define YYTH_MAGIC 0x1B5E783D 40 #define YYTH_FLAG_DIFF_ENCODE 1 41 #define YYTH_FLAG_OOB_TRANS 2 42 #define YYTH_FLAGS (YYTH_FLAG_DIFF_ENCODE | YYTH_FLAG_OOB_TRANS) 43 44 #define MAX_OOB_SUPPORTED 1 45 46 struct table_set_header { 47 u32 th_magic; /* YYTH_MAGIC */ 48 u32 th_hsize; 49 u32 th_ssize; 50 u16 th_flags; 51 char th_version[]; 52 }; 53 54 /* The YYTD_ID are one less than flex table mappings. The flex id 55 * has 1 subtracted at table load time, this allows us to directly use the 56 * ID's as indexes. 57 */ 58 #define YYTD_ID_ACCEPT 0 59 #define YYTD_ID_BASE 1 60 #define YYTD_ID_CHK 2 61 #define YYTD_ID_DEF 3 62 #define YYTD_ID_EC 4 63 #define YYTD_ID_META 5 64 #define YYTD_ID_ACCEPT2 6 65 #define YYTD_ID_NXT 7 66 #define YYTD_ID_TSIZE 8 67 #define YYTD_ID_MAX 8 68 69 #define YYTD_DATA8 1 70 #define YYTD_DATA16 2 71 #define YYTD_DATA32 4 72 #define YYTD_DATA64 8 73 74 /* ACCEPT & ACCEPT2 tables gets 6 dedicated flags, YYTD_DATAX define the 75 * first flags 76 */ 77 #define ACCEPT1_FLAGS(X) ((X) & 0x3f) 78 #define ACCEPT2_FLAGS(X) ACCEPT1_FLAGS((X) >> YYTD_ID_ACCEPT2) 79 #define TO_ACCEPT1_FLAG(X) ACCEPT1_FLAGS(X) 80 #define TO_ACCEPT2_FLAG(X) (ACCEPT1_FLAGS(X) << YYTD_ID_ACCEPT2) 81 #define DFA_FLAG_VERIFY_STATES 0x1000 82 83 struct table_header { 84 u16 td_id; 85 u16 td_flags; 86 u32 td_hilen; 87 u32 td_lolen; 88 char td_data[]; 89 }; 90 91 #define TABLE_DATAU16(TABLE) ((u16 *)((TABLE)->td_data)) 92 #define TABLE_DATAU32(TABLE) ((u32 *)((TABLE)->td_data)) 93 #define DEFAULT_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_DEF]->td_data)) 94 #define BASE_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_BASE]->td_data)) 95 #define NEXT_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_NXT]->td_data)) 96 #define CHECK_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_CHK]->td_data)) 97 #define EQUIV_TABLE(DFA) ((u8 *)((DFA)->tables[YYTD_ID_EC]->td_data)) 98 #define ACCEPT_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT]->td_data)) 99 #define ACCEPT_TABLE2(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT2]->td_data)) 100 101 struct aa_dfa { 102 struct kref count; 103 u16 flags; 104 u32 max_oob; 105 struct table_header *tables[YYTD_ID_TSIZE]; 106 }; 107 108 #define UNPACK_ARRAY(TABLE, BLOB, LEN, TTYPE, BTYPE, NTOHX) \ 109 do { \ 110 typeof(LEN) __i; \ 111 TTYPE *__t = (TTYPE *) TABLE; \ 112 BTYPE *__b = (BTYPE *) BLOB; \ 113 BUILD_BUG_ON(sizeof(TTYPE) != sizeof(BTYPE)); \ 114 if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN)) \ 115 memcpy(__t, __b, (LEN) * sizeof(BTYPE)); \ 116 else /* copy & convert from big-endian */ \ 117 for (__i = 0; __i < LEN; __i++) { \ 118 __t[__i] = NTOHX(&__b[__i]); \ 119 } \ 120 } while (0) 121 122 static inline size_t table_size(size_t len, size_t el_size) 123 { 124 size_t size; 125 126 /* Need check_*_overflow for 32 bit machines */ 127 if (check_mul_overflow(len, el_size, &size) || 128 check_add_overflow(size, sizeof(struct table_header), &size) || 129 size > SIZE_MAX - 7) 130 return 0; 131 132 return ALIGN(size, 8); 133 } 134 135 #define aa_state_t unsigned int 136 137 struct aa_dfa *aa_dfa_unpack(const void *blob, size_t size, int flags); 138 aa_state_t aa_dfa_match_len(const struct aa_dfa *dfa, aa_state_t start, 139 const char *str, int len); 140 aa_state_t aa_dfa_match(const struct aa_dfa *dfa, aa_state_t start, 141 const char *str); 142 aa_state_t aa_dfa_next(const struct aa_dfa *dfa, aa_state_t state, 143 const char c); 144 aa_state_t aa_dfa_outofband_transition(const struct aa_dfa *dfa, 145 aa_state_t state); 146 aa_state_t aa_dfa_match_until(const struct aa_dfa *dfa, aa_state_t start, 147 const char *str, const char **retpos); 148 aa_state_t aa_dfa_matchn_until(const struct aa_dfa *dfa, aa_state_t start, 149 const char *str, int n, const char **retpos); 150 151 void aa_dfa_free_kref(struct kref *kref); 152 153 /* This needs to be a power of 2 */ 154 #define WB_HISTORY_SIZE 32 155 struct match_workbuf { 156 unsigned int pos; 157 unsigned int len; 158 aa_state_t history[WB_HISTORY_SIZE]; 159 }; 160 #define DEFINE_MATCH_WB(N) \ 161 struct match_workbuf N = { \ 162 .pos = 0, \ 163 .len = 0, \ 164 } 165 166 aa_state_t aa_dfa_leftmatch(const struct aa_dfa *dfa, aa_state_t start, 167 const char *str, unsigned int *count); 168 169 /** 170 * aa_get_dfa - increment refcount on dfa @p 171 * @dfa: dfa (MAYBE NULL) 172 * 173 * Returns: pointer to @dfa if @dfa is NULL will return NULL 174 * Requires: @dfa must be held with valid refcount when called 175 */ 176 static inline struct aa_dfa *aa_get_dfa(struct aa_dfa *dfa) 177 { 178 if (dfa) 179 kref_get(&(dfa->count)); 180 181 return dfa; 182 } 183 184 /** 185 * aa_put_dfa - put a dfa refcount 186 * @dfa: dfa to put refcount (MAYBE NULL) 187 * 188 * Requires: if @dfa != NULL that a valid refcount be held 189 */ 190 static inline void aa_put_dfa(struct aa_dfa *dfa) 191 { 192 if (dfa) 193 kref_put(&dfa->count, aa_dfa_free_kref); 194 } 195 196 #define MATCH_FLAG_DIFF_ENCODE 0x80000000 197 #define MARK_DIFF_ENCODE 0x40000000 198 #define MATCH_FLAG_OOB_TRANSITION 0x20000000 199 #define MARK_DIFF_ENCODE_VERIFIED 0x10000000 200 #define MATCH_FLAGS_MASK 0xff000000 201 #define MATCH_FLAGS_VALID (MATCH_FLAG_DIFF_ENCODE | MATCH_FLAG_OOB_TRANSITION) 202 #define MATCH_FLAGS_INVALID (MATCH_FLAGS_MASK & ~MATCH_FLAGS_VALID) 203 204 #endif /* __AA_MATCH_H */ 205