// 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 }, { }, }; static const struct constant_table * __lookup_constant(const struct constant_table *tbl, const char *name) { for ( ; tbl->name; tbl++) if (strcmp(name, tbl->name) == 0) return tbl; return NULL; } /** * lookup_constant - Look up a constant by name in an ordered table * @tbl: The table of constants to search. * @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, const char *name, int not_found) { const struct constant_table *p = __lookup_constant(tbl, name); return p ? p->value : not_found; } EXPORT_SYMBOL(lookup_constant); static inline bool is_flag(const struct fs_parameter_spec *p) { return p->type == NULL; } static const struct fs_parameter_spec *fs_lookup_key( const struct fs_parameter_spec *desc, struct fs_parameter *param, bool *negated) { const struct fs_parameter_spec *p, *other = NULL; const char *name = param->key; bool want_flag = param->type == fs_value_is_flag; *negated = false; for (p = desc; p->name; p++) { if (strcmp(p->name, name) != 0) continue; if (likely(is_flag(p) == want_flag)) return p; other = p; } if (want_flag) { if (name[0] == 'n' && name[1] == 'o' && name[2]) { for (p = desc; p->name; p++) { if (strcmp(p->name, name + 2) != 0) continue; if (!(p->flags & fs_param_neg_with_no)) continue; *negated = true; return p; } } } return other; } /* * 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 p_log *log, const struct fs_parameter_spec *desc, struct fs_parameter *param, struct fs_parse_result *result) { const struct fs_parameter_spec *p; result->uint_64 = 0; p = fs_lookup_key(desc, param, &result->negated); if (!p) return -ENOPARAM; if (p->flags & fs_param_deprecated) warn_plog(log, "Deprecated parameter '%s'", param->key); /* Try to turn the type we were given into the type desired by the * parameter and give an error if we can't. */ if (is_flag(p)) { if (param->type != fs_value_is_flag) return inval_plog(log, "Unexpected value for '%s'", param->key); result->boolean = !result->negated; } else { int ret = p->type(log, p, param, result); if (ret) return ret; } return p->opt; } 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: 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); static int fs_param_bad_value(struct p_log *log, struct fs_parameter *param) { return inval_plog(log, "Bad value for '%s'", param->key); } int fs_param_is_bool(struct p_log *log, const struct fs_parameter_spec *p, struct fs_parameter *param, struct fs_parse_result *result) { int b; if (param->type != fs_value_is_string) return fs_param_bad_value(log, param); b = lookup_constant(bool_names, param->string, -1); if (b == -1) return fs_param_bad_value(log, param); result->boolean = b; return 0; } EXPORT_SYMBOL(fs_param_is_bool); int fs_param_is_u32(struct p_log *log, const struct fs_parameter_spec *p, struct fs_parameter *param, struct fs_parse_result *result) { int base = (unsigned long)p->data; if (param->type != fs_value_is_string || kstrtouint(param->string, base, &result->uint_32) < 0) return fs_param_bad_value(log, param); return 0; } EXPORT_SYMBOL(fs_param_is_u32); int fs_param_is_s32(struct p_log *log, const struct fs_parameter_spec *p, struct fs_parameter *param, struct fs_parse_result *result) { if (param->type != fs_value_is_string || kstrtoint(param->string, 0, &result->int_32) < 0) return fs_param_bad_value(log, param); return 0; } EXPORT_SYMBOL(fs_param_is_s32); int fs_param_is_u64(struct p_log *log, const struct fs_parameter_spec *p, struct fs_parameter *param, struct fs_parse_result *result) { if (param->type != fs_value_is_string || kstrtoull(param->string, 0, &result->uint_64) < 0) return fs_param_bad_value(log, param); return 0; } EXPORT_SYMBOL(fs_param_is_u64); int fs_param_is_enum(struct p_log *log, const struct fs_parameter_spec *p, struct fs_parameter *param, struct fs_parse_result *result) { const struct constant_table *c; if (param->type != fs_value_is_string) return fs_param_bad_value(log, param); c = __lookup_constant(p->data, param->string); if (!c) return fs_param_bad_value(log, param); result->uint_32 = c->value; return 0; } EXPORT_SYMBOL(fs_param_is_enum); int fs_param_is_string(struct p_log *log, const struct fs_parameter_spec *p, struct fs_parameter *param, struct fs_parse_result *result) { if (param->type != fs_value_is_string || !*param->string) return fs_param_bad_value(log, param); return 0; } EXPORT_SYMBOL(fs_param_is_string); int fs_param_is_blob(struct p_log *log, const struct fs_parameter_spec *p, struct fs_parameter *param, struct fs_parse_result *result) { if (param->type != fs_value_is_blob) return fs_param_bad_value(log, param); return 0; } EXPORT_SYMBOL(fs_param_is_blob); int fs_param_is_fd(struct p_log *log, const struct fs_parameter_spec *p, struct fs_parameter *param, struct fs_parse_result *result) { switch (param->type) { case fs_value_is_string: if (kstrtouint(param->string, 0, &result->uint_32) < 0) break; if (result->uint_32 <= INT_MAX) return 0; break; case fs_value_is_file: result->uint_32 = param->dirfd; if (result->uint_32 <= INT_MAX) return 0; break; default: break; } return fs_param_bad_value(log, param); } EXPORT_SYMBOL(fs_param_is_fd); int fs_param_is_blockdev(struct p_log *log, const struct fs_parameter_spec *p, struct fs_parameter *param, struct fs_parse_result *result) { return 0; } EXPORT_SYMBOL(fs_param_is_blockdev); int fs_param_is_path(struct p_log *log, const struct fs_parameter_spec *p, struct fs_parameter *param, struct fs_parse_result *result) { return 0; } EXPORT_SYMBOL(fs_param_is_path); #ifdef CONFIG_VALIDATE_FS_PARSER /** * validate_constant_table - Validate a constant table * @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 * @name: The parameter name to search for. * @desc: The parameter description to validate. */ bool fs_validate_description(const char *name, const struct fs_parameter_spec *desc) { const struct fs_parameter_spec *param, *p2; bool good = true; for (param = desc; param->name; param++) { /* Check for duplicate parameter names */ for (p2 = desc; p2 < param; p2++) { if (strcmp(param->name, p2->name) == 0) { if (is_flag(param) != is_flag(p2)) continue; pr_err("VALIDATE %s: PARAM[%s]: Duplicate\n", name, param->name); good = false; } } } return good; } #endif /* CONFIG_VALIDATE_FS_PARSER */