From patchwork Tue Jul 19 23:41:31 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeremy Bongio X-Patchwork-Id: 12923168 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 5F660CCA47F for ; Tue, 19 Jul 2022 23:41:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239026AbiGSXlj (ORCPT ); Tue, 19 Jul 2022 19:41:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56956 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232291AbiGSXlj (ORCPT ); Tue, 19 Jul 2022 19:41:39 -0400 Received: from mail-pl1-x629.google.com (mail-pl1-x629.google.com [IPv6:2607:f8b0:4864:20::629]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5D7104D17C; Tue, 19 Jul 2022 16:41:38 -0700 (PDT) Received: by mail-pl1-x629.google.com with SMTP id p8so3628555plq.13; Tue, 19 Jul 2022 16:41:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=PqsR5Qa41uqsmBSwrGwuBGBYHH2ruR9RmWHJJrYHuuw=; b=Cm3VoniwbPwxVmYtpDACUHbb+TC1ngFQZjr2AVqXutU05iMZG+Y2QnuITneZhJXqm1 dpukrVAgu1e7Li/UzuJ2qD+FiofXucgeDuCrChnp7AnDjpQnQh3OpEa+HST2QJQPG9in 4NptzAmJaq/zVgR+1SFppTKqAElLWfoT7Id8sLoR9N1HDOXtZpRhkPqfOyl0L2tLoyee iY54ayQtBx6BDrbTdU9mjzQid+mPFu53xjMsomrpb0NXMQUuNNvuh1tHeYN46t0NVj5+ 52gBbu24jGKQflICTKKHV3c/zg5zFOHfnYBDrnw6lJpMnAaA+axT7fdzMRth8I2V/5dF KnUA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=PqsR5Qa41uqsmBSwrGwuBGBYHH2ruR9RmWHJJrYHuuw=; b=VXYYzeiVNVqhJ7QrN8CgcRhUcBlMMeBWwAZ9KVglAXPEMIs7R6WTI1CKohWhrWprOE BdbWGoADc+ZgsJhnxNSNjNCBJeqLFXw3o4m/0DvlT+kyqnrX+OyzEsKMhegRvo2O1EF0 PiJGlup0PnDduZvUSmY+/ASHEXH5E2hb5OWeTMbSHKLkZ4x1Oo0g7KKps+sh1LDIH1j1 TuRpH11KlFBOAjxPdkHqODnsIGtI4uBDiJDGIBTcGlKbknOL0uibNmkTfMxIlEz5RwLE TCGAqKGFqlT4YiquhzPBUPkq8Y2p60y4H5/QWF4RMqrVzGtXnwobNDzAAfOokKyXJm/2 SOiA== X-Gm-Message-State: AJIora/ys+aoItPsLbKsM8MWNFI12vtUCqHxc6rPrzHZmlVMrOsuEifQ +x0j5S1ltoq4UED0Ck/UiAOXlD59l5UKMg== X-Google-Smtp-Source: AGRyM1ul9g2AM6xEXtrh38YKk/niq2P7kj2874xrO8q5T5qlbwx87fUqcA4buHJWN1LNKyr7OesT7A== X-Received: by 2002:a17:902:f546:b0:16b:e4c7:671b with SMTP id h6-20020a170902f54600b0016be4c7671bmr36069613plf.129.1658274097670; Tue, 19 Jul 2022 16:41:37 -0700 (PDT) Received: from jbongio9100214.corp.google.com ([2620:0:102f:1:c88e:7520:969d:1265]) by smtp.googlemail.com with ESMTPSA id w3-20020a626203000000b005253bf1e4d0sm11900379pfb.24.2022.07.19.16.41.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Jul 2022 16:41:37 -0700 (PDT) From: Jeremy Bongio To: Ted Tso Cc: linux-ext4@vger.kernel.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, Jeremy Bongio Subject: [PATCH v4] Add ioctls to get/set the ext4 superblock uuid. Date: Tue, 19 Jul 2022 16:41:31 -0700 Message-Id: <20220719234131.235187-1-bongiojp@gmail.com> X-Mailer: git-send-email 2.37.0.170.g444d1eabd0-goog MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org This fixes a race between changing the ext4 superblock uuid and operations like mounting, resizing, changing features, etc. Reviewed-by: Theodore Ts'o Signed-off-by: Jeremy Bongio --- Changes in v4: Removed unused variable. fs/ext4/ext4.h | 11 +++++++ fs/ext4/ioctl.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 87 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..2c4c3eedfb7b 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 +1141,66 @@ 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 != 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 +1579,10 @@ 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 +1660,8 @@ 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;