// SPDX-License-Identifier: GPL-2.0-or-later /* Filesystem parameter parser. * * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) */ #include <linux/export.h> #include <linux/fs_context.h> #include <linux/fs_parser.h> #include <linux/slab.h> #include <linux/security.h> #include <linux/namei.h> #include "internal.h" static const struct constant_table bool_names[] = { { "0", false }, { "1", true }, { "false", false }, { "no", false }, { "true", true }, { "yes", true }, }; /** * lookup_constant - Look up a constant by name in an ordered table * @tbl: The table of constants to search. * @tbl_size: The size of the table. * @name: The name to look up. * @not_found: The value to return if the name is not found. */ int __lookup_constant(const struct constant_table *tbl, size_t tbl_size, const char *name, int not_found) { unsigned int i; for (i = 0; i < tbl_size; i++) if (strcmp(name, tbl[i].name) == 0) return tbl[i].value; return not_found; } EXPORT_SYMBOL(__lookup_constant); static const struct fs_parameter_spec *fs_lookup_key( const struct fs_parameter_description *desc, const char *name) { const struct fs_parameter_spec *p; if (!desc->specs) return NULL; for (p = desc->specs; p->name; p++) if (strcmp(p->name, name) == 0) return p; return NULL; } /* * fs_parse - Parse a filesystem configuration parameter * @fc: The filesystem context to log errors through. * @desc: The parameter description to use. * @param: The parameter. * @result: Where to place the result of the parse * * Parse a filesystem configuration parameter and attempt a conversion for a * simple parameter for which this is requested. If successful, the determined * parameter ID is placed into @result->key, the desired type is indicated in * @result->t and any converted value is placed into an appropriate member of * the union in @result. * * The function returns the parameter number if the parameter was matched, * -ENOPARAM if it wasn't matched and @desc->ignore_unknown indicated that * unknown parameters are okay and -EINVAL if there was a conversion issue or * the parameter wasn't recognised and unknowns aren't okay. */ int fs_parse(struct fs_context *fc, const struct fs_parameter_description *desc, struct fs_parameter *param, struct fs_parse_result *result) { const struct fs_parameter_spec *p; const struct fs_parameter_enum *e; int ret = -ENOPARAM, b; result->has_value = !!param->string; result->negated = false; result->uint_64 = 0; p = fs_lookup_key(desc, param->key); if (!p) { /* If we didn't find something that looks like "noxxx", see if * "xxx" takes the "no"-form negative - but only if there * wasn't an value. */ if (result->has_value) goto unknown_parameter; if (param->key[0] != 'n' || param->key[1] != 'o' || !param->key[2]) goto unknown_parameter; p = fs_lookup_key(desc, param->key + 2); if (!p) goto unknown_parameter; if (!(p->flags & fs_param_neg_with_no)) goto unknown_parameter; result->boolean = false; result->negated = true; } if (p->flags & fs_param_deprecated) warnf(fc, "%s: Deprecated parameter '%s'", desc->name, param->key); if (result->negated) goto okay; /* Certain parameter types only take a string and convert it. */ switch (p->type) { case __fs_param_wasnt_defined: return -EINVAL; case fs_param_is_u32: case fs_param_is_u32_octal: case fs_param_is_u32_hex: case fs_param_is_s32: case fs_param_is_u64: case fs_param_is_enum: case fs_param_is_string: if (param->type != fs_value_is_string) goto bad_value; if (!result->has_value) { if (p->flags & fs_param_v_optional) goto okay; goto bad_value; } /* Fall through */ default: break; } /* Try to turn the type we were given into the type desired by the * parameter and give an error if we can't. */ switch (p->type) { case fs_param_is_flag: if (param->type != fs_value_is_flag && (param->type != fs_value_is_string || result->has_value)) return invalf(fc, "%s: Unexpected value for '%s'", desc->name, param->key); result->boolean = true; goto okay; case fs_param_is_bool: switch (param->type) { case fs_value_is_flag: result->boolean = true; goto okay; case fs_value_is_string: if (param->size == 0) { result->boolean = true; goto okay; } b = lookup_constant(bool_names, param->string, -1); if (b == -1) goto bad_value; result->boolean = b; goto okay; default: goto bad_value; } case fs_param_is_u32: ret = kstrtouint(param->string, 0, &result->uint_32); goto maybe_okay; case fs_param_is_u32_octal: ret = kstrtouint(param->string, 8, &result->uint_32); goto maybe_okay; case fs_param_is_u32_hex: ret = kstrtouint(param->string, 16, &result->uint_32); goto maybe_okay; case fs_param_is_s32: ret = kstrtoint(param->string, 0, &result->int_32); goto maybe_okay; case fs_param_is_u64: ret = kstrtoull(param->string, 0, &result->uint_64); goto maybe_okay; case fs_param_is_enum: for (e = desc->enums; e->name[0]; e++) { if (e->opt == p->opt && strcmp(e->name, param->string) == 0) { result->uint_32 = e->value; goto okay; } } goto bad_value; case fs_param_is_string: goto okay; case fs_param_is_blob: if (param->type != fs_value_is_blob) goto bad_value; goto okay; case fs_param_is_fd: { if (param->type != fs_value_is_file) goto bad_value; goto okay; } case fs_param_is_blockdev: case fs_param_is_path: goto okay; default: BUG(); } maybe_okay: if (ret < 0) goto bad_value; okay: return p->opt; bad_value: return invalf(fc, "%s: Bad value for '%s'", desc->name, param->key); unknown_parameter: return -ENOPARAM; } EXPORT_SYMBOL(fs_parse); /** * fs_lookup_param - Look up a path referred to by a parameter * @fc: The filesystem context to log errors through. * @param: The parameter. * @want_bdev: T if want a blockdev * @_path: The result of the lookup */ int fs_lookup_param(struct fs_context *fc, struct fs_parameter *param, bool want_bdev, struct path *_path) { struct filename *f; unsigned int flags = 0; bool put_f; int ret; switch (param->type) { case fs_value_is_string: f = getname_kernel(param->string); if (IS_ERR(f)) return PTR_ERR(f); put_f = true; break; case fs_value_is_filename_empty: flags = LOOKUP_EMPTY; /* Fall through */ case fs_value_is_filename: f = param->name; put_f = false; break; default: return invalf(fc, "%s: not usable as path", param->key); } ret = filename_lookup(param->dirfd, f, flags, _path, NULL); if (ret < 0) { errorf(fc, "%s: Lookup failure for '%s'", param->key, f->name); goto out; } if (want_bdev && !S_ISBLK(d_backing_inode(_path->dentry)->i_mode)) { path_put(_path); _path->dentry = NULL; _path->mnt = NULL; errorf(fc, "%s: Non-blockdev passed as '%s'", param->key, f->name); ret = -ENOTBLK; } out: if (put_f) putname(f); return ret; } EXPORT_SYMBOL(fs_lookup_param); #ifdef CONFIG_VALIDATE_FS_PARSER /** * validate_constant_table - Validate a constant table * @name: Name to use in reporting * @tbl: The constant table to validate. * @tbl_size: The size of the table. * @low: The lowest permissible value. * @high: The highest permissible value. * @special: One special permissible value outside of the range. */ bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size, int low, int high, int special) { size_t i; bool good = true; if (tbl_size == 0) { pr_warn("VALIDATE C-TBL: Empty\n"); return true; } for (i = 0; i < tbl_size; i++) { if (!tbl[i].name) { pr_err("VALIDATE C-TBL[%zu]: Null\n", i); good = false; } else if (i > 0 && tbl[i - 1].name) { int c = strcmp(tbl[i-1].name, tbl[i].name); if (c == 0) { pr_err("VALIDATE C-TBL[%zu]: Duplicate %s\n", i, tbl[i].name); good = false; } if (c > 0) { pr_err("VALIDATE C-TBL[%zu]: Missorted %s>=%s\n", i, tbl[i-1].name, tbl[i].name); good = false; } } if (tbl[i].value != special && (tbl[i].value < low || tbl[i].value > high)) { pr_err("VALIDATE C-TBL[%zu]: %s->%d const out of range (%d-%d)\n", i, tbl[i].name, tbl[i].value, low, high); good = false; } } return good; } /** * fs_validate_description - Validate a parameter description * @desc: The parameter description to validate. */ bool fs_validate_description(const struct fs_parameter_description *desc) { const struct fs_parameter_spec *param, *p2; const struct fs_parameter_enum *e; const char *name = desc->name; unsigned int nr_params = 0; bool good = true, enums = false; pr_notice("*** VALIDATE %s ***\n", name); if (!name[0]) { pr_err("VALIDATE Parser: No name\n"); name = "Unknown"; good = false; } if (desc->specs) { for (param = desc->specs; param->name; param++) { enum fs_parameter_type t = param->type; /* Check that the type is in range */ if (t == __fs_param_wasnt_defined || t >= nr__fs_parameter_type) { pr_err("VALIDATE %s: PARAM[%s] Bad type %u\n", name, param->name, t); good = false; } else if (t == fs_param_is_enum) { enums = true; } /* Check for duplicate parameter names */ for (p2 = desc->specs; p2 < param; p2++) { if (strcmp(param->name, p2->name) == 0) { pr_err("VALIDATE %s: PARAM[%s]: Duplicate\n", name, param->name); good = false; } } } nr_params = param - desc->specs; } if (desc->enums) { if (!nr_params) { pr_err("VALIDATE %s: Enum table but no parameters\n", name); good = false; goto no_enums; } if (!enums) { pr_err("VALIDATE %s: Enum table but no enum-type values\n", name); good = false; goto no_enums; } for (e = desc->enums; e->name[0]; e++) { /* Check that all entries in the enum table have at * least one parameter that uses them. */ for (param = desc->specs; param->name; param++) { if (param->opt == e->opt && param->type != fs_param_is_enum) { pr_err("VALIDATE %s: e[%tu] enum val for %s\n", name, e - desc->enums, param->name); good = false; } } } /* Check that all enum-type parameters have at least one enum * value in the enum table. */ for (param = desc->specs; param->name; param++) { if (param->type != fs_param_is_enum) continue; for (e = desc->enums; e->name[0]; e++) if (e->opt == param->opt) break; if (!e->name[0]) { pr_err("VALIDATE %s: PARAM[%s] enum with no values\n", name, param->name); good = false; } } } else { if (enums) { pr_err("VALIDATE %s: enum-type values, but no enum table\n", name); good = false; goto no_enums; } } no_enums: return good; } #endif /* CONFIG_VALIDATE_FS_PARSER */