From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 033BFC43334 for ; Fri, 22 Jul 2022 17:19:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236075AbiGVRTZ (ORCPT ); Fri, 22 Jul 2022 13:19:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41118 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236043AbiGVRTY (ORCPT ); Fri, 22 Jul 2022 13:19:24 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 981F388E2E; Fri, 22 Jul 2022 10:19:22 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 3E6C5B8296E; Fri, 22 Jul 2022 17:19:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EC9E5C341C6; Fri, 22 Jul 2022 17:19:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1658510360; bh=2GxzLl6u2AY30dpZe4mOytY1rt9M1iptzukBSc+uvNQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=UJxniS8lmmHTFUTM5uy+DPiAOXfQGcxbeam9ChAvSfNlVnOaMsQukCr/65+eDs9HO Qu1+UqkzDFRV+os/YhhqDhCbY+27p2kwq8jrfZvLNnU04qdr0jNzhbOm439l1m0XGe oQuyatKHpCQ/zqYzJd4yBCiA7wpsMxIzixh3mgeVA2IdqyXMMtidCnR1WPKDbJwKVl 3wupJCtqLcSK3araWXSOzyR9DX0kW5cHdmZ4lfK9nG74zS+xbTwlFCLGfDuDOGNrIL yY9WccBpySKSzn7tqqx92IiX5OR+Mdairky7xhQSOxLqkYDTa9sunuXLub933qafbC hIM9Ugtvv4mBA== Date: Fri, 22 Jul 2022 10:19:19 -0700 From: "Darrick J. Wong" To: Jeremy Bongio Cc: Ted Tso , linux-ext4@vger.kernel.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v5] Add ioctls to get/set the ext4 superblock uuid. Message-ID: References: <20220721224422.438351-1-bongiojp@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220721224422.438351-1-bongiojp@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Thu, Jul 21, 2022 at 03:44:22PM -0700, Jeremy Bongio wrote: > This fixes a race between changing the ext4 superblock uuid and operations > like mounting, resizing, changing features, etc. > > Reviewed-by: Theodore Ts'o It's possibly too late for this, but: Reviewed-by: Darrick J. Wong --D > Signed-off-by: Jeremy Bongio > --- > > Changes in v5: > > Return size of uuid in a EXT4_IOC_GETFSUUID operation if fsu_len is 0. > > fs/ext4/ext4.h | 11 +++++++ > fs/ext4/ioctl.c | 83 +++++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 94 insertions(+) > > diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h > index 75b8d81b2469..b760d669a1ca 100644 > --- a/fs/ext4/ext4.h > +++ b/fs/ext4/ext4.h > @@ -724,6 +724,8 @@ enum { > #define EXT4_IOC_GETSTATE _IOW('f', 41, __u32) > #define EXT4_IOC_GET_ES_CACHE _IOWR('f', 42, struct fiemap) > #define EXT4_IOC_CHECKPOINT _IOW('f', 43, __u32) > +#define EXT4_IOC_GETFSUUID _IOR('f', 44, struct fsuuid) > +#define EXT4_IOC_SETFSUUID _IOW('f', 44, struct fsuuid) > > #define EXT4_IOC_SHUTDOWN _IOR ('X', 125, __u32) > > @@ -753,6 +755,15 @@ enum { > EXT4_IOC_CHECKPOINT_FLAG_ZEROOUT | \ > EXT4_IOC_CHECKPOINT_FLAG_DRY_RUN) > > +/* > + * Structure for EXT4_IOC_GETFSUUID/EXT4_IOC_SETFSUUID > + */ > +struct fsuuid { > + __u32 fsu_len; > + __u32 fsu_flags; > + __u8 fsu_uuid[]; > +}; > + > #if defined(__KERNEL__) && defined(CONFIG_COMPAT) > /* > * ioctl commands in 32 bit emulation > diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c > index cb01c1da0f9d..b7c9bf9e7864 100644 > --- a/fs/ext4/ioctl.c > +++ b/fs/ext4/ioctl.c > @@ -20,6 +20,7 @@ > #include > #include > #include > +#include > #include "ext4_jbd2.h" > #include "ext4.h" > #include > @@ -41,6 +42,15 @@ static void ext4_sb_setlabel(struct ext4_super_block *es, const void *arg) > memcpy(es->s_volume_name, (char *)arg, EXT4_LABEL_MAX); > } > > +/* > + * Superblock modification callback function for changing file system > + * UUID. > + */ > +static void ext4_sb_setuuid(struct ext4_super_block *es, const void *arg) > +{ > + memcpy(es->s_uuid, (__u8 *)arg, UUID_SIZE); > +} > + > static > int ext4_update_primary_sb(struct super_block *sb, handle_t *handle, > ext4_update_sb_callback func, > @@ -1131,6 +1141,73 @@ static int ext4_ioctl_getlabel(struct ext4_sb_info *sbi, char __user *user_label > return 0; > } > > +static int ext4_ioctl_getuuid(struct ext4_sb_info *sbi, > + struct fsuuid __user *ufsuuid) > +{ > + struct fsuuid fsuuid; > + __u8 uuid[UUID_SIZE]; > + > + if (copy_from_user(&fsuuid, ufsuuid, sizeof(fsuuid))) > + return -EFAULT; > + > + if (fsuuid.fsu_len == 0) { > + fsuuid.fsu_len = UUID_SIZE; > + if (copy_to_user(ufsuuid, &fsuuid, sizeof(fsuuid.fsu_len))) > + return -EFAULT; > + return -EINVAL; > + } > + > + if (fsuuid.fsu_len != UUID_SIZE || fsuuid.fsu_flags != 0) > + return -EINVAL; > + > + lock_buffer(sbi->s_sbh); > + memcpy(uuid, sbi->s_es->s_uuid, UUID_SIZE); > + unlock_buffer(sbi->s_sbh); > + > + if (copy_to_user(&ufsuuid->fsu_uuid[0], uuid, UUID_SIZE)) > + return -EFAULT; > + return 0; > +} > + > +static int ext4_ioctl_setuuid(struct file *filp, > + const struct fsuuid __user *ufsuuid) > +{ > + int ret = 0; > + struct super_block *sb = file_inode(filp)->i_sb; > + struct fsuuid fsuuid; > + __u8 uuid[UUID_SIZE]; > + > + if (!capable(CAP_SYS_ADMIN)) > + return -EPERM; > + > + /* > + * If any checksums (group descriptors or metadata) are being used > + * then the checksum seed feature is required to change the UUID. > + */ > + if (((ext4_has_feature_gdt_csum(sb) || ext4_has_metadata_csum(sb)) > + && !ext4_has_feature_csum_seed(sb)) > + || ext4_has_feature_stable_inodes(sb)) > + return -EOPNOTSUPP; > + > + if (copy_from_user(&fsuuid, ufsuuid, sizeof(fsuuid))) > + return -EFAULT; > + > + if (fsuuid.fsu_len != UUID_SIZE || fsuuid.fsu_flags != 0) > + return -EINVAL; > + > + if (copy_from_user(uuid, &ufsuuid->fsu_uuid[0], UUID_SIZE)) > + return -EFAULT; > + > + ret = mnt_want_write_file(filp); > + if (ret) > + return ret; > + > + ret = ext4_update_superblocks_fn(sb, ext4_sb_setuuid, &uuid); > + mnt_drop_write_file(filp); > + > + return ret; > +} > + > static long __ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) > { > struct inode *inode = file_inode(filp); > @@ -1509,6 +1586,10 @@ static long __ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) > return ext4_ioctl_setlabel(filp, > (const void __user *)arg); > > + case EXT4_IOC_GETFSUUID: > + return ext4_ioctl_getuuid(EXT4_SB(sb), (void __user *)arg); > + case EXT4_IOC_SETFSUUID: > + return ext4_ioctl_setuuid(filp, (const void __user *)arg); > default: > return -ENOTTY; > } > @@ -1586,6 +1667,8 @@ long ext4_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) > case EXT4_IOC_CHECKPOINT: > case FS_IOC_GETFSLABEL: > case FS_IOC_SETFSLABEL: > + case EXT4_IOC_GETFSUUID: > + case EXT4_IOC_SETFSUUID: > break; > default: > return -ENOIOCTLCMD; > -- > 2.37.1.359.gd136c6c3e2-goog >