--- /dev/null
+/* 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 */
--- /dev/null
+/* Filesystem parameter description and 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.
+ */
+
+#ifndef _LINUX_FS_PARSER_H
+#define _LINUX_FS_PARSER_H
+
+#include <linux/fs_context.h>
+
+struct path;
+
+struct constant_table {
+ const char *name;
+ int value;
+};
+
+/*
+ * The type of parameter expected.
+ */
+enum fs_parameter_type {
+ __fs_param_wasnt_defined,
+ fs_param_is_flag,
+ fs_param_is_bool,
+ fs_param_is_u32,
+ fs_param_is_u32_octal,
+ fs_param_is_u32_hex,
+ fs_param_is_s32,
+ fs_param_is_u64,
+ fs_param_is_enum,
+ fs_param_is_string,
+ fs_param_is_blob,
+ fs_param_is_blockdev,
+ fs_param_is_path,
+ fs_param_is_fd,
+ nr__fs_parameter_type,
+};
+
+/*
+ * Specification of the type of value a parameter wants.
+ *
+ * Note that the fsparam_flag(), fsparam_string(), fsparam_u32(), ... macros
+ * should be used to generate elements of this type.
+ */
+struct fs_parameter_spec {
+ const char *name;
+ u8 opt; /* Option number (returned by fs_parse()) */
+ enum fs_parameter_type type:8; /* The desired parameter type */
+ unsigned short flags;
+#define fs_param_v_optional 0x0001 /* The value is optional */
+#define fs_param_neg_with_no 0x0002 /* "noxxx" is negative param */
+#define fs_param_neg_with_empty 0x0004 /* "xxx=" is negative param */
+#define fs_param_deprecated 0x0008 /* The param is deprecated */
+};
+
+struct fs_parameter_enum {
+ u8 opt; /* Option number (as fs_parameter_spec::opt) */
+ char name[14];
+ u8 value;
+};
+
+struct fs_parameter_description {
+ const char name[16]; /* Name for logging purposes */
+ const struct fs_parameter_spec *specs; /* List of param specifications */
+ const struct fs_parameter_enum *enums; /* Enum values */
+};
+
+/*
+ * Result of parse.
+ */
+struct fs_parse_result {
+ bool negated; /* T if param was "noxxx" */
+ bool has_value; /* T if value supplied to param */
+ union {
+ bool boolean; /* For spec_bool */
+ int int_32; /* For spec_s32/spec_enum */
+ unsigned int uint_32; /* For spec_u32{,_octal,_hex}/spec_enum */
+ u64 uint_64; /* For spec_u64 */
+ };
+};
+
+extern int fs_parse(struct fs_context *fc,
+ const struct fs_parameter_description *desc,
+ struct fs_parameter *value,
+ struct fs_parse_result *result);
+extern int fs_lookup_param(struct fs_context *fc,
+ struct fs_parameter *param,
+ bool want_bdev,
+ struct path *_path);
+
+extern int __lookup_constant(const struct constant_table tbl[], size_t tbl_size,
+ const char *name, int not_found);
+#define lookup_constant(t, n, nf) __lookup_constant(t, ARRAY_SIZE(t), (n), (nf))
+
+#ifdef CONFIG_VALIDATE_FS_PARSER
+extern bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
+ int low, int high, int special);
+extern bool fs_validate_description(const struct fs_parameter_description *desc);
+#else
+static inline bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
+ int low, int high, int special)
+{ return true; }
+static inline bool fs_validate_description(const struct fs_parameter_description *desc)
+{ return true; }
+#endif
+
+/*
+ * Parameter type, name, index and flags element constructors. Use as:
+ *
+ * fsparam_xxxx("foo", Opt_foo)
+ *
+ * If existing helpers are not enough, direct use of __fsparam() would
+ * work, but any such case is probably a sign that new helper is needed.
+ * Helpers will remain stable; low-level implementation may change.
+ */
+#define __fsparam(TYPE, NAME, OPT, FLAGS) \
+ { \
+ .name = NAME, \
+ .opt = OPT, \
+ .type = TYPE, \
+ .flags = FLAGS \
+ }
+
+#define fsparam_flag(NAME, OPT) __fsparam(fs_param_is_flag, NAME, OPT, 0)
+#define fsparam_flag_no(NAME, OPT) \
+ __fsparam(fs_param_is_flag, NAME, OPT, \
+ fs_param_neg_with_no)
+#define fsparam_bool(NAME, OPT) __fsparam(fs_param_is_bool, NAME, OPT, 0)
+#define fsparam_u32(NAME, OPT) __fsparam(fs_param_is_u32, NAME, OPT, 0)
+#define fsparam_u32oct(NAME, OPT) \
+ __fsparam(fs_param_is_u32_octal, NAME, OPT, 0)
+#define fsparam_u32hex(NAME, OPT) \
+ __fsparam(fs_param_is_u32_hex, NAME, OPT, 0)
+#define fsparam_s32(NAME, OPT) __fsparam(fs_param_is_s32, NAME, OPT, 0)
+#define fsparam_u64(NAME, OPT) __fsparam(fs_param_is_u64, NAME, OPT, 0)
+#define fsparam_enum(NAME, OPT) __fsparam(fs_param_is_enum, NAME, OPT, 0)
+#define fsparam_string(NAME, OPT) \
+ __fsparam(fs_param_is_string, NAME, OPT, 0)
+#define fsparam_blob(NAME, OPT) __fsparam(fs_param_is_blob, NAME, OPT, 0)
+#define fsparam_bdev(NAME, OPT) __fsparam(fs_param_is_blockdev, NAME, OPT, 0)
+#define fsparam_path(NAME, OPT) __fsparam(fs_param_is_path, NAME, OPT, 0)
+#define fsparam_fd(NAME, OPT) __fsparam(fs_param_is_fd, NAME, OPT, 0)
+
+
+#endif /* _LINUX_FS_PARSER_H */
projects / users / hch / xfs.git / commitdiff