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Message-ID: <003901ceeccb$ce268430$6a738c90$@sx.jp.nec.com>
Date: Fri, 29 Nov 2013 15:25:31 +0900
From: "Kazuya Mio" <k-mio@...jp.nec.com>
To: "'Andreas Dilger'" <adilger@...ger.ca>, <tytso@....edu>
Cc: <linux-ext4@...r.kernel.org>
Subject: RE: [PATCH V4] mke2fs: disallow creating FS on a loop mounted file with no option
Ping?
Any comments/suggestions will be welcome.
Regards,
Kazuya Mio
> 2013/11/07 15:18:05, k-mio@...jp.nec.com wrote:
>
> When /etc/mtab is a symlink of /proc/mounts, mke2fs without -FF option
> can create a filesystem on the image file that is mounted.
> According to mke2fs man page, we should specify -FF option in this case.
>
> This patch protects filesystem from unintended mke2fs caused by human error.
>
> How to reproduce:
> # mke2fs -t ext4 -Fq fs.img
> # mount -o loop fs.img /mnt/mp1
> # mke2fs -t ext4 -Fq fs.img && echo "mke2fs success"
> mke2fs success
>
> Signed-off-by: Kazuya Mio <k-mio@...jp.nec.com>
> ---
> configure.in | 1 +
> lib/ext2fs/ismounted.c | 41 +++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 42 insertions(+)
> diff --git a/configure.in b/configure.in
> index 049dc11..fef8d9b 100644
> --- a/configure.in
> +++ b/configure.in
> @@ -920,6 +920,7 @@ AC_CHECK_HEADERS(m4_flatten([
> linux/falloc.h
> linux/fd.h
> linux/major.h
> + linux/loop.h
> net/if_dl.h
> netinet/in.h
> sys/disklabel.h
> diff --git a/lib/ext2fs/ismounted.c b/lib/ext2fs/ismounted.c
> index 2c1bd75..6c6ecff 100644
> --- a/lib/ext2fs/ismounted.c
> +++ b/lib/ext2fs/ismounted.c
> @@ -21,6 +21,13 @@
> #ifdef HAVE_LINUX_FD_H
> #include <linux/fd.h>
> #endif
> +#ifdef HAVE_LINUX_LOOP_H
> +#include <linux/loop.h>
> +#include <sys/ioctl.h>
> +#ifdef HAVE_LINUX_MAJOR_H
> +#include <linux/major.h>
> +#endif /* HAVE_LINUX_MAJOR_H */
> +#endif /* HAVE_LINUX_LOOP_H */
> #ifdef HAVE_MNTENT_H
> #include <mntent.h>
> #endif
> @@ -35,6 +42,36 @@
> #include "ext2_fs.h"
> #include "ext2fs.h"
>
> +/*
> + * Check to see if a regular file is mounted.
> + * If /etc/mtab/ is a symlink of /proc/mounts, you will need the following check
> + * because the name in /proc/mounts is a loopback device not a regular file.
> + */
> +static int check_loop_mounted(const char *mnt_fsname, dev_t mnt_rdev,
> + dev_t file_dev, ino_t file_ino)
> +{
> +#if defined(HAVE_LINUX_LOOP_H) && defined(HAVE_LINUX_MAJOR_H)
> + struct loop_info64 loopinfo;
> + int loop_fd, ret;
> +
> + if (major(mnt_rdev) == LOOP_MAJOR) {
> + loop_fd = open(mnt_fsname, O_RDONLY);
> + if (loop_fd < 0)
> + return -1;
> +
> + ret = ioctl(loop_fd, LOOP_GET_STATUS64, &loopinfo);
> + close(loop_fd);
> + if (ret < 0)
> + return -1;
> +
> + if (file_dev == loopinfo.lo_device &&
> + file_ino == loopinfo.lo_inode)
> + return 1;
> + }
> +#endif /* defined(HAVE_LINUX_LOOP_H) && defined(HAVE_LINUX_MAJOR_H) */
> + return 0;
> +}
> +
> #ifdef HAVE_SETMNTENT
> /*
> * Helper function which checks a file in /etc/mtab format to see if a
> @@ -82,6 +119,10 @@ static errcode_t check_mntent_file(const char *mtab_file, const char *file,
> #ifndef __GNU__
> if (file_rdev && (file_rdev == st_buf.st_rdev))
> break;
> + if (check_loop_mounted(mnt->mnt_fsname,
> + st_buf.st_rdev, file_dev,
> + file_ino) == 1)
> + break;
> #endif /* __GNU__ */
> } else {
> if (file_dev && ((file_dev == st_buf.st_dev) &&
> --
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