-o remount,rw not possible?

hi list,

i'm using loop-aes for quite a while now and from time to time i had to
remount device-backed loop-aes partitions. eg. a normally r/o mounted
backup partition would become a r/w. i did this like so:

$ mount -o remount,rw /data

when i try this now, mount comes back with

mount: block device /dev/hda1 is write-protected, mounting read-only

i don't know exactly when it stopped working (but i'm pretty sure it
worked a month ago or so). upgrading to the latest loop-aes/ciphers
package did not help.

my setup:

root <at> sheep:~# losetup -a
/dev/loop5: [0805]:173 (/dev/hda1) encryption=twofish128 multi-key read-only
/dev/loop6: [0805]:380 (/dev/sda8) encryption=AES128 multi-key
/dev/loop7: [0805]:389 (/dev/sdb1) encryption=twofish128 multi-key read-only

root <at> sheep:~# uname -r
2.6.10-rc2-bk9

root <at> sheep:~# mount -V
mount: mount-2.12a      <--- stock debian util-linux

Re: -o remount,rw not possible?

Christian Kujau wrote:
> i'm using loop-aes for quite a while now and from time to time i had to
> remount device-backed loop-aes partitions. eg. a normally r/o mounted
> backup partition would become a r/w. i did this like so:
> 
> $ mount -o remount,rw /data
> 
> when i try this now, mount comes back with
> 
> mount: block device /dev/hda1 is write-protected, mounting read-only
> 
> i don't know exactly when it stopped working (but i'm pretty sure it
> worked a month ago or so). upgrading to the latest loop-aes/ciphers
> package did not help.
> 
> my setup:
> 
> root <at> sheep:~# losetup -a
> /dev/loop5: [0805]:173 (/dev/hda1) encryption=twofish128 multi-key read-only
                                                                     ^^^^^^^^^
> /dev/loop6: [0805]:380 (/dev/sda8) encryption=AES128 multi-key
> /dev/loop7: [0805]:389 (/dev/sdb1) encryption=twofish128 multi-key read-only
                                                                     ^^^^^^^^^
When loop was set up, it was set up in "hard" read-only mode, IOW, loop
driver would not permit any writes to reach underlying device. rw mount is
doomed to fail on such read-only loop device. Loop code in loop-AES has
worked like that for long time, years IIRC. OTOH, if VFS is now opening
about-to-rw-mount devices without FMODE_WRITE set, then something is broken
in VFS.

Re: -o remount,rw not possible?

On Thu, December 2, 2004 19:00, Jari Ruusu said:
> When loop was set up, it was set up in "hard" read-only mode, IOW, loop
> driver would not permit any writes to reach underlying device. rw mount is

oh, you're so right Jari. yes, i started to mount the partitions with "ro"
in the first place. i.e. the system boots, "ro" is set in fstab, the loop
device gets setup in "ro" mode and could only be changed when i unmount /
then mount again in "rw" mode. *then* i can use -o remount,rw and -o
remount,ro whenever i like. the inital losetup (done by mount, i guess) is
to "blame" here.

> worked like that for long time, years IIRC. OTOH, if VFS is now opening
> about-to-rw-mount devices without FMODE_WRITE set, then something is
> broken in VFS.

i don't know if that's the case here. i know how to workaround the issue,
but perhaps i should (wishlist)bug the util-linux people here?

thanks for the (always) quick reply,
Christian.
--

-- 
make bzImage, not war

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Linux-crypto:  cryptography in and on the Linux system
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Compiling 3.0a gives me tons of errors

Hello,

I tried checking out the new version, but I can't compile it, like the
last time. I have no idea what's wrong, I tried following this guide:
http://www.meindlsoft.de/doc.php?kb_id=304

Ok, my system:
linux:/home/bstaron/loop-AES-v3.0a# uname -a
Linux linux 2.6.8-1-686 #1 Thu Nov 25 04:34:30 UTC 2004 i686 GNU/Linux

I downloaded and unpacked this source:
http://www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.8.1.tar.bz2

Then:
linux:/home/bstaron/loop-AES-v3.0a# make LINUX_SOURCE=/home/bstaron/linux-2.6.8.1

Then it gives me pages after pages of errors. I don't know if I should
send this to the list, I guess not.... it's 25kb zipped.

The last couple of lines:
/home/bstaron/loop-AES-v3.0a/patched-loop.c:837: error: dereferencing pointer to incomplete type
/home/bstaron/loop-AES-v3.0a/patched-loop.c:839: error: dereferencing pointer to incomplete type
/home/bstaron/loop-AES-v3.0a/patched-loop.c:839: error: dereferencing pointer to incomplete type
/home/bstaron/loop-AES-v3.0a/patched-loop.c:840: error: dereferencing pointer to incomplete type
/home/bstaron/loop-AES-v3.0a/patched-loop.c:841: error: dereferencing pointer to incomplete type
/home/bstaron/loop-AES-v3.0a/patched-loop.c:843: error: dereferencing pointer to incomplete type
/home/bstaron/loop-AES-v3.0a/patched-loop.c:848: error: dereferencing pointer to incomplete type
/home/bstaron/loop-AES-v3.0a/patched-loop.c:848: error: dereferencing pointer to incomplete type
/home/bstaron/loop-AES-v3.0a/patched-loop.c:857: error: dereferencing pointer to incomplete type
/home/bstaron/loop-AES-v3.0a/patched-loop.c:858: error: dereferencing pointer to incomplete type

Re: Compiling 3.0a gives me tons of errors

Bodo Staron wrote:
> Then:
> linux:/home/bstaron/loop-AES-v3.0a# make LINUX_SOURCE=/home/bstaron/linux-2.6.8.1
> 
> Then it gives me pages after pages of errors. I don't know if I should
> send this to the list, I guess not.... it's 25kb zipped.
> 
> The last couple of lines:
> /home/bstaron/loop-AES-v3.0a/patched-loop.c:837: error: dereferencing pointer to incomplete type

Looks like the kernel sources in /home/bstaron/linux-2.6.8.1/ are not ready
for module compiling.

The fix is to recompile and install new kernel in that kernel source
directory and then compile a new loop module for for that new kernel.
Something like this:

    cd /home/bstaron/linux-2.6.8.1/
    mv .config z
    make distclean
    mv z .config
    make oldconfig
    make dep && make clean && make bzImage
    make modules && make modules_install
    cat arch/i386/boot/bzImage >/boot/vmlinuz-2.6.8.1
    cp System.map /boot/System.map-2.6.8.1

    cd /home/bstaron/loop-AES-v3.0a
    make LINUX_SOURCE=/home/bstaron/linux-2.6.8.1

Hallo Frau/Herr linux-crypto: Meine Kontakt Daten

Hallo liebe Freunde, Verwandte und Bekannte,

Ich schicke Euch nach langer Zeit meine Kontakt Daten und freue mich
ueber jede Antwort. Sie wird beantwortet werden auch wenn es etwas
dauert.

Bitte schaut doch auch auf meine Homepage
http://markus.freeshell.org
Oder
http://www.cyber-worker.info/~mark

und vielleicht wisst Ihr was der eine oder die andere macht von dem/der
ich nur noch tote Emails besitze :( (unten auf der Homepage)

Meine Email:
mailto:sagebiel <at> yahoo.com
:)

Tote Email ab Fruehjahr 05
sage <at> biel.com
:(

Viele Gruesse aus Leipheim / Ulm
Markus

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Re[2]: Compiling 3.0a gives me tons of errors

Hello,

JR> Looks like the kernel sources in /home/bstaron/linux-2.6.8.1/ are not ready
JR> for module compiling.

JR> The fix is to recompile and install new kernel in that kernel source
JR> directory and then compile a new loop module for for that new kernel.
JR> Something like this:

Great. Everything works again :)
However, one question remains. In the current readme this part:
===================================================================
In multi-key loop cases "losetup -a" command run by root user should
output "multi-key-v3" indicating that loop is really in multi-key-v3
mode. If no "multi-key-v3" string shows up, your loop setup is a time
bomb.
===================================================================

Well, I did a complete install, also util-linux as described in the
readme. After everything was installed and reboot and mount I see this:

linux:/home/bstaron# losetup -a
/dev/loop3: [0305]:684215 (/dev/hda7) encryption=AES128 multi-key-v2

This is of course created with one of the 2.2 versions of loop-aes.
It seems it's normal for an old keyfile. I created a new keyfile and partition
with v3 and it shows multi key v3.

--

-- 
bye,

Re: Compiling 3.0a gives me tons of errors

Bodo Staron wrote:
> However, one question remains. In the current readme this part:
> ===================================================================
> In multi-key loop cases "losetup -a" command run by root user should
> output "multi-key-v3" indicating that loop is really in multi-key-v3
> mode. If no "multi-key-v3" string shows up, your loop setup is a time
> bomb.
> ===================================================================
> 
> Well, I did a complete install, also util-linux as described in the
> readme. After everything was installed and reboot and mount I see this:
> 
> linux:/home/bstaron# losetup -a
> /dev/loop3: [0305]:684215 (/dev/hda7) encryption=AES128 multi-key-v2
> 
> This is of course created with one of the 2.2 versions of loop-aes.
> It seems it's normal for an old keyfile.

Yes, that is normal for version 2 on-disk format.

> I created a new keyfile and partition with v3 and it shows multi key v3.

That is normal for version 3 on-disk format.

--

-- 
Jari Ruusu  1024R/3A220F51 5B 4B F9 BB D3 3F 52 E9  DB 1D EB E3 24 0E A9 DD

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