2019-02-11 06:15:55

by Theodore Ts'o

Subject: [PATCH] ext4: disallow files with EXT4_JOURNAL_DATA_FL from EXT4_IOC_SWAP_BOOT

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 <[email protected]>
---
fs/ext4/ioctl.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 2e76fb55d94a..eb8ca8d80885 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;
--
2.19.1

2019-02-12 12:42:08

by yangerkun

Subject: Re: [PATCH] ext4: disallow files with EXT4_JOURNAL_DATA_FL from EXT4_IOC_SWAP_BOOT

Reviewed-by: yangerkun <[email protected]>

Theodore Ts'o wrote on 2019/2/11 14:15:
> 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 <[email protected]>
> ---
> fs/ext4/ioctl.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
> index 2e76fb55d94a..eb8ca8d80885 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;
>