// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2012 Red Hat, Inc.
 * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
 */

#include <linux/efi.h>
#include <linux/fs.h>
#include <linux/ctype.h>
#include <linux/kmemleak.h>
#include <linux/slab.h>
#include <linux/uuid.h>
#include <linux/fileattr.h>

#include "internal.h"

static const struct inode_operations efivarfs_file_inode_operations;

struct inode *efivarfs_get_inode(struct super_block *sb,
                                const struct inode *dir, int mode,
                                dev_t dev, bool is_removable)
{
        struct inode *inode = new_inode(sb);
        struct efivarfs_fs_info *fsi = sb->s_fs_info;
        struct efivarfs_mount_opts *opts = &fsi->mount_opts;

        if (inode) {
                inode->i_uid = opts->uid;
                inode->i_gid = opts->gid;
                inode->i_ino = get_next_ino();
                inode->i_mode = mode;
                simple_inode_init_ts(inode);
                inode->i_flags = is_removable ? 0 : S_IMMUTABLE;
                switch (mode & S_IFMT) {
                case S_IFREG:
                        inode->i_op = &efivarfs_file_inode_operations;
                        inode->i_fop = &efivarfs_file_operations;
                        break;
                case S_IFDIR:
                        inode->i_op = &efivarfs_dir_inode_operations;
                        inode->i_fop = &simple_dir_operations;
                        inc_nlink(inode);
                        break;
                }
        }
        return inode;
}

/*
 * Return true if 'str' is a valid efivarfs filename of the form,
 *
 *      VariableName-12345678-1234-1234-1234-1234567891bc
 */
static bool efivarfs_valid_name(const char *str, int len)
{
        const char *s = str + len - EFI_VARIABLE_GUID_LEN;

        /*
         * We need a GUID, plus at least one letter for the variable name,
         * plus the '-' separator
         */
        if (len < EFI_VARIABLE_GUID_LEN + 2)
                return false;

        /* GUID must be preceded by a '-' */
        if (*(s - 1) != '-')
                return false;

        /*
         * Validate that 's' is of the correct format, e.g.
         *
         *      12345678-1234-1234-1234-123456789abc
         */
        return uuid_is_valid(s);
}

static int efivarfs_create(struct mnt_idmap *idmap, struct inode *dir,
                           struct dentry *dentry, umode_t mode, bool excl)
{
        struct inode *inode = NULL;
        struct efivar_entry *var;
        int namelen, i = 0, err = 0;
        bool is_removable = false;
        efi_guid_t vendor;

        if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len))
                return -EINVAL;

        /* length of the variable name itself: remove GUID and separator */
        namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1;

        err = guid_parse(dentry->d_name.name + namelen + 1, &vendor);
        if (err)
                return err;
        if (guid_equal(&vendor, &LINUX_EFI_RANDOM_SEED_TABLE_GUID))
                return -EPERM;

        if (efivar_variable_is_removable(vendor,
                                         dentry->d_name.name, namelen))
                is_removable = true;

        inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0, is_removable);
        if (!inode)
                return -ENOMEM;
        var = efivar_entry(inode);

        var->var.VendorGuid = vendor;

        for (i = 0; i < namelen; i++)
                var->var.VariableName[i] = dentry->d_name.name[i];

        var->var.VariableName[i] = '\0';

        inode->i_private = var;

        d_make_persistent(dentry, inode);

        return 0;
}

static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
{
        struct efivar_entry *var = d_inode(dentry)->i_private;

        if (efivar_entry_delete(var))
                return -EINVAL;

        return simple_unlink(dir, dentry);
};

const struct inode_operations efivarfs_dir_inode_operations = {
        .lookup = simple_lookup,
        .unlink = efivarfs_unlink,
        .create = efivarfs_create,
};

static int
efivarfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
{
        unsigned int i_flags;
        unsigned int flags = 0;

        i_flags = d_inode(dentry)->i_flags;
        if (i_flags & S_IMMUTABLE)
                flags |= FS_IMMUTABLE_FL;

        fileattr_fill_flags(fa, flags);

        return 0;
}

static int
efivarfs_fileattr_set(struct mnt_idmap *idmap,
                      struct dentry *dentry, struct file_kattr *fa)
{
        unsigned int i_flags = 0;

        if (fileattr_has_fsx(fa))
                return -EOPNOTSUPP;

        if (fa->flags & ~FS_IMMUTABLE_FL)
                return -EOPNOTSUPP;

        if (fa->flags & FS_IMMUTABLE_FL)
                i_flags |= S_IMMUTABLE;

        inode_set_flags(d_inode(dentry), i_flags, S_IMMUTABLE);

        return 0;
}

/* copy of simple_setattr except that it doesn't do i_size updates */
static int efivarfs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
                   struct iattr *iattr)
{
        struct inode *inode = d_inode(dentry);
        int error;

        error = setattr_prepare(idmap, dentry, iattr);
        if (error)
                return error;

        setattr_copy(idmap, inode, iattr);
        mark_inode_dirty(inode);
        return 0;
}

static const struct inode_operations efivarfs_file_inode_operations = {
        .fileattr_get = efivarfs_fileattr_get,
        .fileattr_set = efivarfs_fileattr_set,
        .setattr      = efivarfs_setattr,
};