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 */ 197