linux-kernel - [PATCH 4.14 040/173] ubifs: Fix FS_IOC_SETFLAGS unexpectedly clearing encrypt flag

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Message-Id: <20200213151944.026374406@linuxfoundation.org>
Date:   Thu, 13 Feb 2020 07:19:03 -0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Eric Biggers <ebiggers@...gle.com>,
        Richard Weinberger <richard@....at>
Subject: [PATCH 4.14 040/173] ubifs: Fix FS_IOC_SETFLAGS unexpectedly clearing encrypt flag

From: Eric Biggers <ebiggers@...gle.com>

commit 2b57067a7778484c10892fa191997bfda29fea13 upstream.

UBIFS's implementation of FS_IOC_SETFLAGS fails to preserve existing
inode flags that aren't settable by FS_IOC_SETFLAGS, namely the encrypt
flag.  This causes the encrypt flag to be unexpectedly cleared.

Fix it by preserving existing unsettable flags, like ext4 and f2fs do.

Test case with kvm-xfstests shell:

    FSTYP=ubifs KEYCTL_PROG=keyctl
    . fs/ubifs/config
    . ~/xfstests/common/encrypt
    dev=$(__blkdev_to_ubi_volume /dev/vdc)
    ubiupdatevol -t $dev
    mount $dev /mnt -t ubifs
    k=$(_generate_session_encryption_key)
    mkdir /mnt/edir
    xfs_io -c "set_encpolicy $k" /mnt/edir
    echo contents > /mnt/edir/file
    chattr +i /mnt/edir/file
    chattr -i /mnt/edir/file

With the bug, the following errors occur on the last command:

    [   18.081559] fscrypt (ubifs, inode 67): Inconsistent encryption context (parent directory: 65)
    chattr: Operation not permitted while reading flags on /mnt/edir/file

Fixes: d475a507457b ("ubifs: Add skeleton for fscrypto")
Cc: <stable@...r.kernel.org> # v4.10+
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
Signed-off-by: Richard Weinberger <richard@....at>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/ubifs/ioctl.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/ubifs/ioctl.c
+++ b/fs/ubifs/ioctl.c
@@ -129,7 +129,8 @@ static int setflags(struct inode *inode,
 		}
 	}
 
-	ui->flags = ioctl2ubifs(flags);
+	ui->flags &= ~ioctl2ubifs(UBIFS_SUPPORTED_IOCTL_FLAGS);
+	ui->flags |= ioctl2ubifs(flags);
 	ubifs_set_inode_flags(inode);
 	inode->i_ctime = current_time(inode);
 	release = ui->dirty;