From 935ec1eb3def7c3caa86a45959349cfa6a98aa22 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Thu, 19 May 2022 13:44:37 -0700 Subject: [PATCH] ext4: only allow test_dummy_encryption when supported Make the test_dummy_encryption mount option require that the encrypt feature flag be already enabled on the filesystem, rather than automatically enabling it. Practically, this means that "-O encrypt" will need to be included in MKFS_OPTIONS when running xfstests with the test_dummy_encryption mount option. (ext4/053 also needs an update.) Moreover, as long as the preconditions for test_dummy_encryption are being tightened anyway, take the opportunity to start rejecting it when !CONFIG_FS_ENCRYPTION rather than ignoring it. The motivation for requiring the encrypt feature flag is that: - Having the filesystem auto-enable feature flags is problematic, as it bypasses the usual sanity checks. The specific issue which came up recently is that in kernel versions where ext4 supports casefold but not encrypt+casefold (v5.1 through v5.10), the kernel will happily add the encrypt flag to a filesystem that has the casefold flag, making it unmountable -- but only for subsequent mounts, not the initial one. This confused the casefold support detection in xfstests, causing generic/556 to fail rather than be skipped. - The xfstests-bld test runners (kvm-xfstests et al.) already use the required mkfs flag, so they will not be affected by this change. Only users of test_dummy_encryption alone will be affected. But, this option has always been for testing only, so it should be fine to require that the few users of this option update their test scripts. - f2fs already requires it (for its equivalent feature flag). Signed-off-by: Eric Biggers Reviewed-by: Gabriel Krisman Bertazi Link: https://lore.kernel.org/r/20220519204437.61645-1-ebiggers@kernel.org Signed-off-by: Theodore Ts'o --- fs/ext4/ext4.h | 6 ----- fs/ext4/super.c | 60 +++++++++++++++++++++++++++++++------------------ 2 files changed, 38 insertions(+), 28 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index a16d77b292773..d5cea9c2e2a2d 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1442,12 +1442,6 @@ struct ext4_super_block { #ifdef __KERNEL__ -#ifdef CONFIG_FS_ENCRYPTION -#define DUMMY_ENCRYPTION_ENABLED(sbi) ((sbi)->s_dummy_enc_policy.policy != NULL) -#else -#define DUMMY_ENCRYPTION_ENABLED(sbi) (0) -#endif - /* Number of quota types we support */ #define EXT4_MAXQUOTAS 3 diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 9cbb220453790..8ff4c6545a49c 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2308,11 +2308,12 @@ static int ext4_parse_param(struct fs_context *fc, struct fs_parameter *param) ctx->spec |= EXT4_SPEC_DUMMY_ENCRYPTION; ctx->test_dummy_enc_arg = kmemdup_nul(param->string, param->size, GFP_KERNEL); + return 0; #else ext4_msg(NULL, KERN_WARNING, - "Test dummy encryption mount option ignored"); + "test_dummy_encryption option not supported"); + return -EINVAL; #endif - return 0; case Opt_dax: case Opt_dax_type: #ifdef CONFIG_FS_DAX @@ -2669,12 +2670,44 @@ err_jquota_specified: #endif } +static int ext4_check_test_dummy_encryption(const struct fs_context *fc, + struct super_block *sb) +{ +#ifdef CONFIG_FS_ENCRYPTION + const struct ext4_fs_context *ctx = fc->fs_private; + const struct ext4_sb_info *sbi = EXT4_SB(sb); + + if (!(ctx->spec & EXT4_SPEC_DUMMY_ENCRYPTION)) + return 0; + + if (!ext4_has_feature_encrypt(sb)) { + ext4_msg(NULL, KERN_WARNING, + "test_dummy_encryption requires encrypt feature"); + return -EINVAL; + } + /* + * This mount option is just for testing, and it's not worthwhile to + * implement the extra complexity (e.g. RCU protection) that would be + * needed to allow it to be set or changed during remount. We do allow + * it to be specified during remount, but only if there is no change. + */ + if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE && + !sbi->s_dummy_enc_policy.policy) { + ext4_msg(NULL, KERN_WARNING, + "Can't set test_dummy_encryption on remount"); + return -EINVAL; + } +#endif /* CONFIG_FS_ENCRYPTION */ + return 0; +} + static int ext4_check_opt_consistency(struct fs_context *fc, struct super_block *sb) { struct ext4_fs_context *ctx = fc->fs_private; struct ext4_sb_info *sbi = fc->s_fs_info; int is_remount = fc->purpose == FS_CONTEXT_FOR_RECONFIGURE; + int err; if ((ctx->opt_flags & MOPT_NO_EXT2) && IS_EXT2_SB(sb)) { ext4_msg(NULL, KERN_ERR, @@ -2704,20 +2737,9 @@ static int ext4_check_opt_consistency(struct fs_context *fc, "for blocksize < PAGE_SIZE"); } -#ifdef CONFIG_FS_ENCRYPTION - /* - * This mount option is just for testing, and it's not worthwhile to - * implement the extra complexity (e.g. RCU protection) that would be - * needed to allow it to be set or changed during remount. We do allow - * it to be specified during remount, but only if there is no change. - */ - if ((ctx->spec & EXT4_SPEC_DUMMY_ENCRYPTION) && - is_remount && !sbi->s_dummy_enc_policy.policy) { - ext4_msg(NULL, KERN_WARNING, - "Can't set test_dummy_encryption on remount"); - return -1; - } -#endif + err = ext4_check_test_dummy_encryption(fc, sb); + if (err) + return err; if ((ctx->spec & EXT4_SPEC_DATAJ) && is_remount) { if (!sbi->s_journal) { @@ -5163,12 +5185,6 @@ no_journal: goto failed_mount_wq; } - if (DUMMY_ENCRYPTION_ENABLED(sbi) && !sb_rdonly(sb) && - !ext4_has_feature_encrypt(sb)) { - ext4_set_feature_encrypt(sb); - ext4_commit_super(sb); - } - /* * Get the # of file system overhead blocks from the * superblock if present. -- 2.39.5