1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* Filesystem parameter parser. 3 * 4 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 */ 7 8 #include <linux/export.h> 9 #include <linux/fs_context.h> 10 #include <linux/fs_parser.h> 11 #include <linux/slab.h> 12 #include <linux/security.h> 13 #include <linux/namei.h> 14 #include "internal.h" 15 16 static const struct constant_table bool_names[] = { 17 { "0", false }, 18 { "1", true }, 19 { "false", false }, 20 { "no", false }, 21 { "true", true }, 22 { "yes", true }, 23 }; 24 25 /** 26 * lookup_constant - Look up a constant by name in an ordered table 27 * @tbl: The table of constants to search. 28 * @tbl_size: The size of the table. 29 * @name: The name to look up. 30 * @not_found: The value to return if the name is not found. 31 */ 32 int __lookup_constant(const struct constant_table *tbl, size_t tbl_size, 33 const char *name, int not_found) 34 { 35 unsigned int i; 36 37 for (i = 0; i < tbl_size; i++) 38 if (strcmp(name, tbl[i].name) == 0) 39 return tbl[i].value; 40 41 return not_found; 42 } 43 EXPORT_SYMBOL(__lookup_constant); 44 45 static const struct fs_parameter_spec *fs_lookup_key( 46 const struct fs_parameter_description *desc, 47 const char *name) 48 { 49 const struct fs_parameter_spec *p; 50 51 if (!desc->specs) 52 return NULL; 53 54 for (p = desc->specs; p->name; p++) 55 if (strcmp(p->name, name) == 0) 56 return p; 57 58 return NULL; 59 } 60 61 /* 62 * fs_parse - Parse a filesystem configuration parameter 63 * @fc: The filesystem context to log errors through. 64 * @desc: The parameter description to use. 65 * @param: The parameter. 66 * @result: Where to place the result of the parse 67 * 68 * Parse a filesystem configuration parameter and attempt a conversion for a 69 * simple parameter for which this is requested. If successful, the determined 70 * parameter ID is placed into @result->key, the desired type is indicated in 71 * @result->t and any converted value is placed into an appropriate member of 72 * the union in @result. 73 * 74 * The function returns the parameter number if the parameter was matched, 75 * -ENOPARAM if it wasn't matched and @desc->ignore_unknown indicated that 76 * unknown parameters are okay and -EINVAL if there was a conversion issue or 77 * the parameter wasn't recognised and unknowns aren't okay. 78 */ 79 int fs_parse(struct fs_context *fc, 80 const struct fs_parameter_description *desc, 81 struct fs_parameter *param, 82 struct fs_parse_result *result) 83 { 84 const struct fs_parameter_spec *p; 85 const struct fs_parameter_enum *e; 86 int ret = -ENOPARAM, b; 87 88 result->has_value = !!param->string; 89 result->negated = false; 90 result->uint_64 = 0; 91 92 p = fs_lookup_key(desc, param->key); 93 if (!p) { 94 /* If we didn't find something that looks like "noxxx", see if 95 * "xxx" takes the "no"-form negative - but only if there 96 * wasn't an value. 97 */ 98 if (result->has_value) 99 goto unknown_parameter; 100 if (param->key[0] != 'n' || param->key[1] != 'o' || !param->key[2]) 101 goto unknown_parameter; 102 103 p = fs_lookup_key(desc, param->key + 2); 104 if (!p) 105 goto unknown_parameter; 106 if (!(p->flags & fs_param_neg_with_no)) 107 goto unknown_parameter; 108 result->boolean = false; 109 result->negated = true; 110 } 111 112 if (p->flags & fs_param_deprecated) 113 warnf(fc, "%s: Deprecated parameter '%s'", 114 desc->name, param->key); 115 116 if (result->negated) 117 goto okay; 118 119 /* Certain parameter types only take a string and convert it. */ 120 switch (p->type) { 121 case __fs_param_wasnt_defined: 122 return -EINVAL; 123 case fs_param_is_u32: 124 case fs_param_is_u32_octal: 125 case fs_param_is_u32_hex: 126 case fs_param_is_s32: 127 case fs_param_is_u64: 128 case fs_param_is_enum: 129 case fs_param_is_string: 130 if (param->type != fs_value_is_string) 131 goto bad_value; 132 if (!result->has_value) { 133 if (p->flags & fs_param_v_optional) 134 goto okay; 135 goto bad_value; 136 } 137 /* Fall through */ 138 default: 139 break; 140 } 141 142 /* Try to turn the type we were given into the type desired by the 143 * parameter and give an error if we can't. 144 */ 145 switch (p->type) { 146 case fs_param_is_flag: 147 if (param->type != fs_value_is_flag && 148 (param->type != fs_value_is_string || result->has_value)) 149 return invalf(fc, "%s: Unexpected value for '%s'", 150 desc->name, param->key); 151 result->boolean = true; 152 goto okay; 153 154 case fs_param_is_bool: 155 switch (param->type) { 156 case fs_value_is_flag: 157 result->boolean = true; 158 goto okay; 159 case fs_value_is_string: 160 if (param->size == 0) { 161 result->boolean = true; 162 goto okay; 163 } 164 b = lookup_constant(bool_names, param->string, -1); 165 if (b == -1) 166 goto bad_value; 167 result->boolean = b; 168 goto okay; 169 default: 170 goto bad_value; 171 } 172 173 case fs_param_is_u32: 174 ret = kstrtouint(param->string, 0, &result->uint_32); 175 goto maybe_okay; 176 case fs_param_is_u32_octal: 177 ret = kstrtouint(param->string, 8, &result->uint_32); 178 goto maybe_okay; 179 case fs_param_is_u32_hex: 180 ret = kstrtouint(param->string, 16, &result->uint_32); 181 goto maybe_okay; 182 case fs_param_is_s32: 183 ret = kstrtoint(param->string, 0, &result->int_32); 184 goto maybe_okay; 185 case fs_param_is_u64: 186 ret = kstrtoull(param->string, 0, &result->uint_64); 187 goto maybe_okay; 188 189 case fs_param_is_enum: 190 for (e = desc->enums; e->name[0]; e++) { 191 if (e->opt == p->opt && 192 strcmp(e->name, param->string) == 0) { 193 result->uint_32 = e->value; 194 goto okay; 195 } 196 } 197 goto bad_value; 198 199 case fs_param_is_string: 200 goto okay; 201 case fs_param_is_blob: 202 if (param->type != fs_value_is_blob) 203 goto bad_value; 204 goto okay; 205 206 case fs_param_is_fd: { 207 if (param->type != fs_value_is_file) 208 goto bad_value; 209 goto okay; 210 } 211 212 case fs_param_is_blockdev: 213 case fs_param_is_path: 214 goto okay; 215 default: 216 BUG(); 217 } 218 219 maybe_okay: 220 if (ret < 0) 221 goto bad_value; 222 okay: 223 return p->opt; 224 225 bad_value: 226 return invalf(fc, "%s: Bad value for '%s'", desc->name, param->key); 227 unknown_parameter: 228 return -ENOPARAM; 229 } 230 EXPORT_SYMBOL(fs_parse); 231 232 /** 233 * fs_lookup_param - Look up a path referred to by a parameter 234 * @fc: The filesystem context to log errors through. 235 * @param: The parameter. 236 * @want_bdev: T if want a blockdev 237 * @_path: The result of the lookup 238 */ 239 int fs_lookup_param(struct fs_context *fc, 240 struct fs_parameter *param, 241 bool want_bdev, 242 struct path *_path) 243 { 244 struct filename *f; 245 unsigned int flags = 0; 246 bool put_f; 247 int ret; 248 249 switch (param->type) { 250 case fs_value_is_string: 251 f = getname_kernel(param->string); 252 if (IS_ERR(f)) 253 return PTR_ERR(f); 254 put_f = true; 255 break; 256 case fs_value_is_filename_empty: 257 flags = LOOKUP_EMPTY; 258 /* Fall through */ 259 case fs_value_is_filename: 260 f = param->name; 261 put_f = false; 262 break; 263 default: 264 return invalf(fc, "%s: not usable as path", param->key); 265 } 266 267 ret = filename_lookup(param->dirfd, f, flags, _path, NULL); 268 if (ret < 0) { 269 errorf(fc, "%s: Lookup failure for '%s'", param->key, f->name); 270 goto out; 271 } 272 273 if (want_bdev && 274 !S_ISBLK(d_backing_inode(_path->dentry)->i_mode)) { 275 path_put(_path); 276 _path->dentry = NULL; 277 _path->mnt = NULL; 278 errorf(fc, "%s: Non-blockdev passed as '%s'", 279 param->key, f->name); 280 ret = -ENOTBLK; 281 } 282 283 out: 284 if (put_f) 285 putname(f); 286 return ret; 287 } 288 EXPORT_SYMBOL(fs_lookup_param); 289 290 #ifdef CONFIG_VALIDATE_FS_PARSER 291 /** 292 * validate_constant_table - Validate a constant table 293 * @name: Name to use in reporting 294 * @tbl: The constant table to validate. 295 * @tbl_size: The size of the table. 296 * @low: The lowest permissible value. 297 * @high: The highest permissible value. 298 * @special: One special permissible value outside of the range. 299 */ 300 bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size, 301 int low, int high, int special) 302 { 303 size_t i; 304 bool good = true; 305 306 if (tbl_size == 0) { 307 pr_warn("VALIDATE C-TBL: Empty\n"); 308 return true; 309 } 310 311 for (i = 0; i < tbl_size; i++) { 312 if (!tbl[i].name) { 313 pr_err("VALIDATE C-TBL[%zu]: Null\n", i); 314 good = false; 315 } else if (i > 0 && tbl[i - 1].name) { 316 int c = strcmp(tbl[i-1].name, tbl[i].name); 317 318 if (c == 0) { 319 pr_err("VALIDATE C-TBL[%zu]: Duplicate %s\n", 320 i, tbl[i].name); 321 good = false; 322 } 323 if (c > 0) { 324 pr_err("VALIDATE C-TBL[%zu]: Missorted %s>=%s\n", 325 i, tbl[i-1].name, tbl[i].name); 326 good = false; 327 } 328 } 329 330 if (tbl[i].value != special && 331 (tbl[i].value < low || tbl[i].value > high)) { 332 pr_err("VALIDATE C-TBL[%zu]: %s->%d const out of range (%d-%d)\n", 333 i, tbl[i].name, tbl[i].value, low, high); 334 good = false; 335 } 336 } 337 338 return good; 339 } 340 341 /** 342 * fs_validate_description - Validate a parameter description 343 * @desc: The parameter description to validate. 344 */ 345 bool fs_validate_description(const struct fs_parameter_description *desc) 346 { 347 const struct fs_parameter_spec *param, *p2; 348 const struct fs_parameter_enum *e; 349 const char *name = desc->name; 350 unsigned int nr_params = 0; 351 bool good = true, enums = false; 352 353 pr_notice("*** VALIDATE %s ***\n", name); 354 355 if (!name[0]) { 356 pr_err("VALIDATE Parser: No name\n"); 357 name = "Unknown"; 358 good = false; 359 } 360 361 if (desc->specs) { 362 for (param = desc->specs; param->name; param++) { 363 enum fs_parameter_type t = param->type; 364 365 /* Check that the type is in range */ 366 if (t == __fs_param_wasnt_defined || 367 t >= nr__fs_parameter_type) { 368 pr_err("VALIDATE %s: PARAM[%s] Bad type %u\n", 369 name, param->name, t); 370 good = false; 371 } else if (t == fs_param_is_enum) { 372 enums = true; 373 } 374 375 /* Check for duplicate parameter names */ 376 for (p2 = desc->specs; p2 < param; p2++) { 377 if (strcmp(param->name, p2->name) == 0) { 378 pr_err("VALIDATE %s: PARAM[%s]: Duplicate\n", 379 name, param->name); 380 good = false; 381 } 382 } 383 } 384 385 nr_params = param - desc->specs; 386 } 387 388 if (desc->enums) { 389 if (!nr_params) { 390 pr_err("VALIDATE %s: Enum table but no parameters\n", 391 name); 392 good = false; 393 goto no_enums; 394 } 395 if (!enums) { 396 pr_err("VALIDATE %s: Enum table but no enum-type values\n", 397 name); 398 good = false; 399 goto no_enums; 400 } 401 402 for (e = desc->enums; e->name[0]; e++) { 403 /* Check that all entries in the enum table have at 404 * least one parameter that uses them. 405 */ 406 for (param = desc->specs; param->name; param++) { 407 if (param->opt == e->opt && 408 param->type != fs_param_is_enum) { 409 pr_err("VALIDATE %s: e[%tu] enum val for %s\n", 410 name, e - desc->enums, param->name); 411 good = false; 412 } 413 } 414 } 415 416 /* Check that all enum-type parameters have at least one enum 417 * value in the enum table. 418 */ 419 for (param = desc->specs; param->name; param++) { 420 if (param->type != fs_param_is_enum) 421 continue; 422 for (e = desc->enums; e->name[0]; e++) 423 if (e->opt == param->opt) 424 break; 425 if (!e->name[0]) { 426 pr_err("VALIDATE %s: PARAM[%s] enum with no values\n", 427 name, param->name); 428 good = false; 429 } 430 } 431 } else { 432 if (enums) { 433 pr_err("VALIDATE %s: enum-type values, but no enum table\n", 434 name); 435 good = false; 436 goto no_enums; 437 } 438 } 439 440 no_enums: 441 return good; 442 } 443 #endif /* CONFIG_VALIDATE_FS_PARSER */ 444