[stgt] [PATCH 2/2] tgt-admin: check if device is mounted on /

Doron Shoham dorons at Voltaire.COM
Tue Sep 2 15:51:46 CEST 2008

Tomasz Chmielewski wrote:

> Generally, any filesystem mounted on the target should not be allocated
> to initiators. Disallowing / (i.e., /dev/sda1), but allowing /usr (i.e.,
> /dev/sda2) or swap is certainly not a good idea.
> The info can be fetched from /etc/mtab (unless we have a system with
> read-only /etc, where /etc/mtab could be a link to /proc/mounts - I
> think /proc/mounts doesn't always show an underlying device where rootfs
> sits). Also, parsing /proc/swaps would be useful.
> But what if someone has rootfs on /dev/mtd0, mtd0 consists of /dev/sda1
> and /dev/sdb1 - and wants to allocate /dev/sdb to initiators? Not to say
> LVM, dm-crypt devices, etc... - it looks like there are lots of
> possibilities for an admin to break the system ;)
> If someone is brave (or uses a distributed fs on the target) and really
> wants to allow initiators access to a mounted filesystem, we could add a
> separate option for that ("allow-mounted")?
> Although I guess it wouldn't have many users today.

For the beginning we will just disallow any filesystem mounted on the target.
Later we can expand it to handle /dev/mtd0, LVM and so on.

If I understood correctly, we need to:
1. parse /etc/matb - read the device which mounted on /
Doesn't the rootfs will be always mounted on /, even if we use nfs?
2. parse /proc/mounts - read all the devices
compare the devices we found to the device we want to allocate.
3. Add allow-mounted option to override this action and allow the allocation.

Do you have any suggestions about handling other situations as you described above (/dev/mtd0, LVM, etc...)?


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