diff options
Diffstat (limited to 'fs/fs_parser.c')
| -rw-r--r-- | fs/fs_parser.c | 400 |
1 files changed, 400 insertions, 0 deletions
diff --git a/fs/fs_parser.c b/fs/fs_parser.c new file mode 100644 index 000000000..edb3712dc --- /dev/null +++ b/fs/fs_parser.c @@ -0,0 +1,400 @@ +// 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 + * @flags: Pathwalk flags passed to filename_lookup() + * @_path: The result of the lookup + */ +int fs_lookup_param(struct fs_context *fc, + struct fs_parameter *param, + bool want_bdev, + unsigned int flags, + struct path *_path) +{ + struct filename *f; + 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); + if (!*param->string && (p->flags & fs_param_can_be_empty)) + return 0; + 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) + return fs_param_bad_value(log, param); + if (!*param->string && (p->flags & fs_param_can_be_empty)) + return 0; + if (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) + return fs_param_bad_value(log, param); + if (!*param->string && (p->flags & fs_param_can_be_empty)) + return 0; + if (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) + return fs_param_bad_value(log, param); + if (!*param->string && (p->flags & fs_param_can_be_empty)) + return 0; + if (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); + if (!*param->string && (p->flags & fs_param_can_be_empty)) + return 0; + 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 && !(p->flags & fs_param_can_be_empty))) + 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 ((!*param->string && !(p->flags & fs_param_can_be_empty)) || + 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 */ |