1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * AppArmor security module 4 * 5 * This file contains AppArmor functions for unpacking policy loaded 6 * from userspace. 7 * 8 * Copyright (C) 1998-2008 Novell/SUSE 9 * Copyright 2009-2022 Canonical Ltd. 10 * 11 * Code to provide backwards compatibility with older policy versions, 12 * by converting/mapping older policy formats into the newer internal 13 * formats. 14 */ 15 16 #include <linux/ctype.h> 17 #include <linux/errno.h> 18 19 #include "include/lib.h" 20 #include "include/policy_unpack.h" 21 #include "include/policy_compat.h" 22 23 /* remap old accept table embedded permissions to separate permission table */ 24 static u32 dfa_map_xindex(u16 mask) 25 { 26 u16 old_index = (mask >> 10) & 0xf; 27 u32 index = 0; 28 29 if (mask & 0x100) 30 index |= AA_X_UNSAFE; 31 if (mask & 0x200) 32 index |= AA_X_INHERIT; 33 if (mask & 0x80) 34 index |= AA_X_UNCONFINED; 35 36 if (old_index == 1) { 37 index |= AA_X_UNCONFINED; 38 } else if (old_index == 2) { 39 index |= AA_X_NAME; 40 } else if (old_index == 3) { 41 index |= AA_X_NAME | AA_X_CHILD; 42 } else if (old_index) { 43 index |= AA_X_TABLE; 44 index |= old_index - 4; 45 } 46 47 return index; 48 } 49 50 /* 51 * map old dfa inline permissions to new format 52 */ 53 #define dfa_user_allow(dfa, state) (((ACCEPT_TABLE(dfa)[state]) & 0x7f) | \ 54 ((ACCEPT_TABLE(dfa)[state]) & 0x80000000)) 55 #define dfa_user_xbits(dfa, state) (((ACCEPT_TABLE(dfa)[state]) >> 7) & 0x7f) 56 #define dfa_user_audit(dfa, state) ((ACCEPT_TABLE2(dfa)[state]) & 0x7f) 57 #define dfa_user_quiet(dfa, state) (((ACCEPT_TABLE2(dfa)[state]) >> 7) & 0x7f) 58 #define dfa_user_xindex(dfa, state) \ 59 (dfa_map_xindex(ACCEPT_TABLE(dfa)[state] & 0x3fff)) 60 61 #define dfa_other_allow(dfa, state) ((((ACCEPT_TABLE(dfa)[state]) >> 14) & \ 62 0x7f) | \ 63 ((ACCEPT_TABLE(dfa)[state]) & 0x80000000)) 64 #define dfa_other_xbits(dfa, state) \ 65 ((((ACCEPT_TABLE(dfa)[state]) >> 7) >> 14) & 0x7f) 66 #define dfa_other_audit(dfa, state) (((ACCEPT_TABLE2(dfa)[state]) >> 14) & 0x7f) 67 #define dfa_other_quiet(dfa, state) \ 68 ((((ACCEPT_TABLE2(dfa)[state]) >> 7) >> 14) & 0x7f) 69 #define dfa_other_xindex(dfa, state) \ 70 dfa_map_xindex((ACCEPT_TABLE(dfa)[state] >> 14) & 0x3fff) 71 72 /** 73 * map_old_perms - map old file perms layout to the new layout 74 * @old: permission set in old mapping 75 * 76 * Returns: new permission mapping 77 */ 78 static u32 map_old_perms(u32 old) 79 { 80 u32 new = old & 0xf; 81 82 if (old & MAY_READ) 83 new |= AA_MAY_GETATTR | AA_MAY_OPEN; 84 if (old & MAY_WRITE) 85 new |= AA_MAY_SETATTR | AA_MAY_CREATE | AA_MAY_DELETE | 86 AA_MAY_CHMOD | AA_MAY_CHOWN | AA_MAY_OPEN; 87 if (old & 0x10) 88 new |= AA_MAY_LINK; 89 /* the old mapping lock and link_subset flags where overlaid 90 * and use was determined by part of a pair that they were in 91 */ 92 if (old & 0x20) 93 new |= AA_MAY_LOCK | AA_LINK_SUBSET; 94 if (old & 0x40) /* AA_EXEC_MMAP */ 95 new |= AA_EXEC_MMAP; 96 97 return new; 98 } 99 100 static void compute_fperms_allow(struct aa_perms *perms, struct aa_dfa *dfa, 101 aa_state_t state) 102 { 103 perms->allow |= AA_MAY_GETATTR; 104 105 /* change_profile wasn't determined by ownership in old mapping */ 106 if (ACCEPT_TABLE(dfa)[state] & 0x80000000) 107 perms->allow |= AA_MAY_CHANGE_PROFILE; 108 if (ACCEPT_TABLE(dfa)[state] & 0x40000000) 109 perms->allow |= AA_MAY_ONEXEC; 110 } 111 112 static struct aa_perms compute_fperms_user(struct aa_dfa *dfa, 113 aa_state_t state) 114 { 115 struct aa_perms perms = { }; 116 117 perms.allow = map_old_perms(dfa_user_allow(dfa, state)); 118 perms.audit = map_old_perms(dfa_user_audit(dfa, state)); 119 perms.quiet = map_old_perms(dfa_user_quiet(dfa, state)); 120 perms.xindex = dfa_user_xindex(dfa, state); 121 122 compute_fperms_allow(&perms, dfa, state); 123 124 return perms; 125 } 126 127 static struct aa_perms compute_fperms_other(struct aa_dfa *dfa, 128 aa_state_t state) 129 { 130 struct aa_perms perms = { }; 131 132 perms.allow = map_old_perms(dfa_other_allow(dfa, state)); 133 perms.audit = map_old_perms(dfa_other_audit(dfa, state)); 134 perms.quiet = map_old_perms(dfa_other_quiet(dfa, state)); 135 perms.xindex = dfa_other_xindex(dfa, state); 136 137 compute_fperms_allow(&perms, dfa, state); 138 139 return perms; 140 } 141 142 /** 143 * compute_fperms - convert dfa compressed perms to internal perms and store 144 * them so they can be retrieved later. 145 * @dfa: a dfa using fperms to remap to internal permissions 146 * 147 * Returns: remapped perm table 148 */ 149 static struct aa_perms *compute_fperms(struct aa_dfa *dfa) 150 { 151 aa_state_t state; 152 unsigned int state_count; 153 struct aa_perms *table; 154 155 AA_BUG(!dfa); 156 157 state_count = dfa->tables[YYTD_ID_BASE]->td_lolen; 158 /* DFAs are restricted from having a state_count of less than 2 */ 159 table = kvcalloc(state_count * 2, sizeof(struct aa_perms), GFP_KERNEL); 160 if (!table) 161 return NULL; 162 163 /* zero init so skip the trap state (state == 0) */ 164 for (state = 1; state < state_count; state++) { 165 table[state * 2] = compute_fperms_user(dfa, state); 166 table[state * 2 + 1] = compute_fperms_other(dfa, state); 167 } 168 169 return table; 170 } 171 172 static struct aa_perms *compute_xmatch_perms(struct aa_dfa *xmatch) 173 { 174 struct aa_perms *perms; 175 int state; 176 int state_count; 177 178 AA_BUG(!xmatch); 179 180 state_count = xmatch->tables[YYTD_ID_BASE]->td_lolen; 181 /* DFAs are restricted from having a state_count of less than 2 */ 182 perms = kvcalloc(state_count, sizeof(struct aa_perms), GFP_KERNEL); 183 184 /* zero init so skip the trap state (state == 0) */ 185 for (state = 1; state < state_count; state++) 186 perms[state].allow = dfa_user_allow(xmatch, state); 187 188 return perms; 189 } 190 191 static u32 map_other(u32 x) 192 { 193 return ((x & 0x3) << 8) | /* SETATTR/GETATTR */ 194 ((x & 0x1c) << 18) | /* ACCEPT/BIND/LISTEN */ 195 ((x & 0x60) << 19); /* SETOPT/GETOPT */ 196 } 197 198 static u32 map_xbits(u32 x) 199 { 200 return ((x & 0x1) << 7) | 201 ((x & 0x7e) << 9); 202 } 203 204 static struct aa_perms compute_perms_entry(struct aa_dfa *dfa, 205 aa_state_t state, 206 u32 version) 207 { 208 struct aa_perms perms = { }; 209 210 perms.allow = dfa_user_allow(dfa, state); 211 perms.audit = dfa_user_audit(dfa, state); 212 perms.quiet = dfa_user_quiet(dfa, state); 213 214 /* 215 * This mapping is convulated due to history. 216 * v1-v4: only file perms, which are handled by compute_fperms 217 * v5: added policydb which dropped user conditional to gain new 218 * perm bits, but had to map around the xbits because the 219 * userspace compiler was still munging them. 220 * v9: adds using the xbits in policydb because the compiler now 221 * supports treating policydb permission bits different. 222 * Unfortunately there is no way to force auditing on the 223 * perms represented by the xbits 224 */ 225 perms.allow |= map_other(dfa_other_allow(dfa, state)); 226 if (VERSION_LE(version, v8)) 227 perms.allow |= AA_MAY_LOCK; 228 else 229 perms.allow |= map_xbits(dfa_user_xbits(dfa, state)); 230 231 /* 232 * for v5-v9 perm mapping in the policydb, the other set is used 233 * to extend the general perm set 234 */ 235 perms.audit |= map_other(dfa_other_audit(dfa, state)); 236 perms.quiet |= map_other(dfa_other_quiet(dfa, state)); 237 if (VERSION_GT(version, v8)) 238 perms.quiet |= map_xbits(dfa_other_xbits(dfa, state)); 239 240 return perms; 241 } 242 243 static struct aa_perms *compute_perms(struct aa_dfa *dfa, u32 version) 244 { 245 unsigned int state; 246 unsigned int state_count; 247 struct aa_perms *table; 248 249 AA_BUG(!dfa); 250 251 state_count = dfa->tables[YYTD_ID_BASE]->td_lolen; 252 /* DFAs are restricted from having a state_count of less than 2 */ 253 table = kvcalloc(state_count, sizeof(struct aa_perms), GFP_KERNEL); 254 if (!table) 255 return NULL; 256 257 /* zero init so skip the trap state (state == 0) */ 258 for (state = 1; state < state_count; state++) 259 table[state] = compute_perms_entry(dfa, state, version); 260 261 return table; 262 } 263 264 /** 265 * remap_dfa_accept - remap old dfa accept table to be an index 266 * @dfa: dfa to do the remapping on 267 * @factor: scaling factor for the index conversion. 268 * 269 * Used in conjunction with compute_Xperms, it converts old style perms 270 * that are encoded in the dfa accept tables to the new style where 271 * there is a permission table and the accept table is an index into 272 * the permission table. 273 */ 274 static void remap_dfa_accept(struct aa_dfa *dfa, unsigned int factor) 275 { 276 unsigned int state; 277 unsigned int state_count = dfa->tables[YYTD_ID_BASE]->td_lolen; 278 279 AA_BUG(!dfa); 280 281 for (state = 0; state < state_count; state++) 282 ACCEPT_TABLE(dfa)[state] = state * factor; 283 kvfree(dfa->tables[YYTD_ID_ACCEPT2]); 284 dfa->tables[YYTD_ID_ACCEPT2] = NULL; 285 } 286 287 /* TODO: merge different dfa mappings into single map_policy fn */ 288 int aa_compat_map_xmatch(struct aa_policydb *policy) 289 { 290 policy->perms = compute_xmatch_perms(policy->dfa); 291 if (!policy->perms) 292 return -ENOMEM; 293 294 remap_dfa_accept(policy->dfa, 1); 295 296 return 0; 297 } 298 299 int aa_compat_map_policy(struct aa_policydb *policy, u32 version) 300 { 301 policy->perms = compute_perms(policy->dfa, version); 302 if (!policy->perms) 303 return -ENOMEM; 304 305 remap_dfa_accept(policy->dfa, 1); 306 307 return 0; 308 } 309 310 int aa_compat_map_file(struct aa_policydb *policy) 311 { 312 policy->perms = compute_fperms(policy->dfa); 313 if (!policy->perms) 314 return -ENOMEM; 315 316 remap_dfa_accept(policy->dfa, 2); 317 318 return 0; 319 } 320