diff options
Diffstat (limited to 'fs/fs_parser.c')
| -rw-r--r-- | fs/fs_parser.c | 447 |
1 files changed, 447 insertions, 0 deletions
diff --git a/fs/fs_parser.c b/fs/fs_parser.c new file mode 100644 index 000000000000..842e8f749db6 --- /dev/null +++ b/fs/fs_parser.c @@ -0,0 +1,447 @@ +/* Filesystem parameter parser. + * + * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ + +#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[%lu] 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 */ |