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 */