linux-kernel - [PATCH 4.19 052/149] ext4: disallow files with EXT4_JOURNAL_DATA_FL from EXT4_IOC_SWAP

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Message-Id: <20191104212139.867962840@linuxfoundation.org>
Date:   Mon,  4 Nov 2019 22:44:05 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Theodore Tso <tytso@....edu>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 052/149] ext4: disallow files with EXT4_JOURNAL_DATA_FL from EXT4_IOC_SWAP_BOOT

From: Theodore Ts'o <tytso@....edu>

[ Upstream commit 6e589291f4b1b700ca12baec5930592a0d51e63c ]

A malicious/clueless root user can use EXT4_IOC_SWAP_BOOT to force a
corner casew which can lead to the file system getting corrupted.
There's no usefulness to allowing this, so just prohibit this case.

Signed-off-by: Theodore Ts'o <tytso@....edu>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/ext4/ioctl.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index abb6fcff0a1d3..783c54bb2ce75 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -132,6 +132,7 @@ static long swap_inode_boot_loader(struct super_block *sb,
 
 	if (inode->i_nlink != 1 || !S_ISREG(inode->i_mode) ||
 	    IS_SWAPFILE(inode) || IS_ENCRYPTED(inode) ||
+	    (EXT4_I(inode)->i_flags & EXT4_JOURNAL_DATA_FL) ||
 	    ext4_has_inline_data(inode)) {
 		err = -EINVAL;
 		goto journal_err_out;
-- 
2.20.1