1 /* Filesystem parameter parser. 2 * 3 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved. 4 * Written by David Howells (dhowells@redhat.com) 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public Licence 8 * as published by the Free Software Foundation; either version 9 * 2 of the Licence, or (at your option) any later version. 10 */ 11 12 #include <linux/export.h> 13 #include <linux/fs_context.h> 14 #include <linux/fs_parser.h> 15 #include <linux/slab.h> 16 #include <linux/security.h> 17 #include <linux/namei.h> 18 #include "internal.h" 19 20 static const struct constant_table bool_names[] = { 21 { "0", false }, 22 { "1", true }, 23 { "false", false }, 24 { "no", false }, 25 { "true", true }, 26 { "yes", true }, 27 }; 28 29 /** 30 * lookup_constant - Look up a constant by name in an ordered table 31 * @tbl: The table of constants to search. 32 * @tbl_size: The size of the table. 33 * @name: The name to look up. 34 * @not_found: The value to return if the name is not found. 35 */ 36 int __lookup_constant(const struct constant_table *tbl, size_t tbl_size, 37 const char *name, int not_found) 38 { 39 unsigned int i; 40 41 for (i = 0; i < tbl_size; i++) 42 if (strcmp(name, tbl[i].name) == 0) 43 return tbl[i].value; 44 45 return not_found; 46 } 47 EXPORT_SYMBOL(__lookup_constant); 48 49 static const struct fs_parameter_spec *fs_lookup_key( 50 const struct fs_parameter_description *desc, 51 const char *name) 52 { 53 const struct fs_parameter_spec *p; 54 55 if (!desc->specs) 56 return NULL; 57 58 for (p = desc->specs; p->name; p++) 59 if (strcmp(p->name, name) == 0) 60 return p; 61 62 return NULL; 63 } 64 65 /* 66 * fs_parse - Parse a filesystem configuration parameter 67 * @fc: The filesystem context to log errors through. 68 * @desc: The parameter description to use. 69 * @param: The parameter. 70 * @result: Where to place the result of the parse 71 * 72 * Parse a filesystem configuration parameter and attempt a conversion for a 73 * simple parameter for which this is requested. If successful, the determined 74 * parameter ID is placed into @result->key, the desired type is indicated in 75 * @result->t and any converted value is placed into an appropriate member of 76 * the union in @result. 77 * 78 * The function returns the parameter number if the parameter was matched, 79 * -ENOPARAM if it wasn't matched and @desc->ignore_unknown indicated that 80 * unknown parameters are okay and -EINVAL if there was a conversion issue or 81 * the parameter wasn't recognised and unknowns aren't okay. 82 */ 83 int fs_parse(struct fs_context *fc, 84 const struct fs_parameter_description *desc, 85 struct fs_parameter *param, 86 struct fs_parse_result *result) 87 { 88 const struct fs_parameter_spec *p; 89 const struct fs_parameter_enum *e; 90 int ret = -ENOPARAM, b; 91 92 result->has_value = !!param->string; 93 result->negated = false; 94 result->uint_64 = 0; 95 96 p = fs_lookup_key(desc, param->key); 97 if (!p) { 98 /* If we didn't find something that looks like "noxxx", see if 99 * "xxx" takes the "no"-form negative - but only if there 100 * wasn't an value. 101 */ 102 if (result->has_value) 103 goto unknown_parameter; 104 if (param->key[0] != 'n' || param->key[1] != 'o' || !param->key[2]) 105 goto unknown_parameter; 106 107 p = fs_lookup_key(desc, param->key + 2); 108 if (!p) 109 goto unknown_parameter; 110 if (!(p->flags & fs_param_neg_with_no)) 111 goto unknown_parameter; 112 result->boolean = false; 113 result->negated = true; 114 } 115 116 if (p->flags & fs_param_deprecated) 117 warnf(fc, "%s: Deprecated parameter '%s'", 118 desc->name, param->key); 119 120 if (result->negated) 121 goto okay; 122 123 /* Certain parameter types only take a string and convert it. */ 124 switch (p->type) { 125 case __fs_param_wasnt_defined: 126 return -EINVAL; 127 case fs_param_is_u32: 128 case fs_param_is_u32_octal: 129 case fs_param_is_u32_hex: 130 case fs_param_is_s32: 131 case fs_param_is_u64: 132 case fs_param_is_enum: 133 case fs_param_is_string: 134 if (param->type != fs_value_is_string) 135 goto bad_value; 136 if (!result->has_value) { 137 if (p->flags & fs_param_v_optional) 138 goto okay; 139 goto bad_value; 140 } 141 /* Fall through */ 142 default: 143 break; 144 } 145 146 /* Try to turn the type we were given into the type desired by the 147 * parameter and give an error if we can't. 148 */ 149 switch (p->type) { 150 case fs_param_is_flag: 151 if (param->type != fs_value_is_flag && 152 (param->type != fs_value_is_string || result->has_value)) 153 return invalf(fc, "%s: Unexpected value for '%s'", 154 desc->name, param->key); 155 result->boolean = true; 156 goto okay; 157 158 case fs_param_is_bool: 159 switch (param->type) { 160 case fs_value_is_flag: 161 result->boolean = true; 162 goto okay; 163 case fs_value_is_string: 164 if (param->size == 0) { 165 result->boolean = true; 166 goto okay; 167 } 168 b = lookup_constant(bool_names, param->string, -1); 169 if (b == -1) 170 goto bad_value; 171 result->boolean = b; 172 goto okay; 173 default: 174 goto bad_value; 175 } 176 177 case fs_param_is_u32: 178 ret = kstrtouint(param->string, 0, &result->uint_32); 179 goto maybe_okay; 180 case fs_param_is_u32_octal: 181 ret = kstrtouint(param->string, 8, &result->uint_32); 182 goto maybe_okay; 183 case fs_param_is_u32_hex: 184 ret = kstrtouint(param->string, 16, &result->uint_32); 185 goto maybe_okay; 186 case fs_param_is_s32: 187 ret = kstrtoint(param->string, 0, &result->int_32); 188 goto maybe_okay; 189 case fs_param_is_u64: 190 ret = kstrtoull(param->string, 0, &result->uint_64); 191 goto maybe_okay; 192 193 case fs_param_is_enum: 194 for (e = desc->enums; e->name[0]; e++) { 195 if (e->opt == p->opt && 196 strcmp(e->name, param->string) == 0) { 197 result->uint_32 = e->value; 198 goto okay; 199 } 200 } 201 goto bad_value; 202 203 case fs_param_is_string: 204 goto okay; 205 case fs_param_is_blob: 206 if (param->type != fs_value_is_blob) 207 goto bad_value; 208 goto okay; 209 210 case fs_param_is_fd: { 211 if (param->type != fs_value_is_file) 212 goto bad_value; 213 goto okay; 214 } 215 216 case fs_param_is_blockdev: 217 case fs_param_is_path: 218 goto okay; 219 default: 220 BUG(); 221 } 222 223 maybe_okay: 224 if (ret < 0) 225 goto bad_value; 226 okay: 227 return p->opt; 228 229 bad_value: 230 return invalf(fc, "%s: Bad value for '%s'", desc->name, param->key); 231 unknown_parameter: 232 return -ENOPARAM; 233 } 234 EXPORT_SYMBOL(fs_parse); 235 236 /** 237 * fs_lookup_param - Look up a path referred to by a parameter 238 * @fc: The filesystem context to log errors through. 239 * @param: The parameter. 240 * @want_bdev: T if want a blockdev 241 * @_path: The result of the lookup 242 */ 243 int fs_lookup_param(struct fs_context *fc, 244 struct fs_parameter *param, 245 bool want_bdev, 246 struct path *_path) 247 { 248 struct filename *f; 249 unsigned int flags = 0; 250 bool put_f; 251 int ret; 252 253 switch (param->type) { 254 case fs_value_is_string: 255 f = getname_kernel(param->string); 256 if (IS_ERR(f)) 257 return PTR_ERR(f); 258 put_f = true; 259 break; 260 case fs_value_is_filename_empty: 261 flags = LOOKUP_EMPTY; 262 /* Fall through */ 263 case fs_value_is_filename: 264 f = param->name; 265 put_f = false; 266 break; 267 default: 268 return invalf(fc, "%s: not usable as path", param->key); 269 } 270 271 ret = filename_lookup(param->dirfd, f, flags, _path, NULL); 272 if (ret < 0) { 273 errorf(fc, "%s: Lookup failure for '%s'", param->key, f->name); 274 goto out; 275 } 276 277 if (want_bdev && 278 !S_ISBLK(d_backing_inode(_path->dentry)->i_mode)) { 279 path_put(_path); 280 _path->dentry = NULL; 281 _path->mnt = NULL; 282 errorf(fc, "%s: Non-blockdev passed as '%s'", 283 param->key, f->name); 284 ret = -ENOTBLK; 285 } 286 287 out: 288 if (put_f) 289 putname(f); 290 return ret; 291 } 292 EXPORT_SYMBOL(fs_lookup_param); 293 294 #ifdef CONFIG_VALIDATE_FS_PARSER 295 /** 296 * validate_constant_table - Validate a constant table 297 * @name: Name to use in reporting 298 * @tbl: The constant table to validate. 299 * @tbl_size: The size of the table. 300 * @low: The lowest permissible value. 301 * @high: The highest permissible value. 302 * @special: One special permissible value outside of the range. 303 */ 304 bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size, 305 int low, int high, int special) 306 { 307 size_t i; 308 bool good = true; 309 310 if (tbl_size == 0) { 311 pr_warn("VALIDATE C-TBL: Empty\n"); 312 return true; 313 } 314 315 for (i = 0; i < tbl_size; i++) { 316 if (!tbl[i].name) { 317 pr_err("VALIDATE C-TBL[%zu]: Null\n", i); 318 good = false; 319 } else if (i > 0 && tbl[i - 1].name) { 320 int c = strcmp(tbl[i-1].name, tbl[i].name); 321 322 if (c == 0) { 323 pr_err("VALIDATE C-TBL[%zu]: Duplicate %s\n", 324 i, tbl[i].name); 325 good = false; 326 } 327 if (c > 0) { 328 pr_err("VALIDATE C-TBL[%zu]: Missorted %s>=%s\n", 329 i, tbl[i-1].name, tbl[i].name); 330 good = false; 331 } 332 } 333 334 if (tbl[i].value != special && 335 (tbl[i].value < low || tbl[i].value > high)) { 336 pr_err("VALIDATE C-TBL[%zu]: %s->%d const out of range (%d-%d)\n", 337 i, tbl[i].name, tbl[i].value, low, high); 338 good = false; 339 } 340 } 341 342 return good; 343 } 344 345 /** 346 * fs_validate_description - Validate a parameter description 347 * @desc: The parameter description to validate. 348 */ 349 bool fs_validate_description(const struct fs_parameter_description *desc) 350 { 351 const struct fs_parameter_spec *param, *p2; 352 const struct fs_parameter_enum *e; 353 const char *name = desc->name; 354 unsigned int nr_params = 0; 355 bool good = true, enums = false; 356 357 pr_notice("*** VALIDATE %s ***\n", name); 358 359 if (!name[0]) { 360 pr_err("VALIDATE Parser: No name\n"); 361 name = "Unknown"; 362 good = false; 363 } 364 365 if (desc->specs) { 366 for (param = desc->specs; param->name; param++) { 367 enum fs_parameter_type t = param->type; 368 369 /* Check that the type is in range */ 370 if (t == __fs_param_wasnt_defined || 371 t >= nr__fs_parameter_type) { 372 pr_err("VALIDATE %s: PARAM[%s] Bad type %u\n", 373 name, param->name, t); 374 good = false; 375 } else if (t == fs_param_is_enum) { 376 enums = true; 377 } 378 379 /* Check for duplicate parameter names */ 380 for (p2 = desc->specs; p2 < param; p2++) { 381 if (strcmp(param->name, p2->name) == 0) { 382 pr_err("VALIDATE %s: PARAM[%s]: Duplicate\n", 383 name, param->name); 384 good = false; 385 } 386 } 387 } 388 389 nr_params = param - desc->specs; 390 } 391 392 if (desc->enums) { 393 if (!nr_params) { 394 pr_err("VALIDATE %s: Enum table but no parameters\n", 395 name); 396 good = false; 397 goto no_enums; 398 } 399 if (!enums) { 400 pr_err("VALIDATE %s: Enum table but no enum-type values\n", 401 name); 402 good = false; 403 goto no_enums; 404 } 405 406 for (e = desc->enums; e->name[0]; e++) { 407 /* Check that all entries in the enum table have at 408 * least one parameter that uses them. 409 */ 410 for (param = desc->specs; param->name; param++) { 411 if (param->opt == e->opt && 412 param->type != fs_param_is_enum) { 413 pr_err("VALIDATE %s: e[%lu] enum val for %s\n", 414 name, e - desc->enums, param->name); 415 good = false; 416 } 417 } 418 } 419 420 /* Check that all enum-type parameters have at least one enum 421 * value in the enum table. 422 */ 423 for (param = desc->specs; param->name; param++) { 424 if (param->type != fs_param_is_enum) 425 continue; 426 for (e = desc->enums; e->name[0]; e++) 427 if (e->opt == param->opt) 428 break; 429 if (!e->name[0]) { 430 pr_err("VALIDATE %s: PARAM[%s] enum with no values\n", 431 name, param->name); 432 good = false; 433 } 434 } 435 } else { 436 if (enums) { 437 pr_err("VALIDATE %s: enum-type values, but no enum table\n", 438 name); 439 good = false; 440 goto no_enums; 441 } 442 } 443 444 no_enums: 445 return good; 446 } 447 #endif /* CONFIG_VALIDATE_FS_PARSER */ 448