[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
** Merge proposal linked: https://code.launchpad.net/~crass/casper/+git/casper/+merge/453083 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to the bug report. https://bugs.launchpad.net/bugs/41624 Title: Replaying journals of other OS's filesystems, by mounting them, is unsafe To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/iso-scan/+bug/41624/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
Over a decade later... but this might help someone. There is a way around this mess, with some caveats. You can set the block device to readonly using blockdev. This works as desired a lot of the time. However, sometimes (or perhaps everytime certain filesystems need to replay the journal), the will cause the kernel to refuse to mount the filesystem. The way around this is to, as mentioned above, replay the journal to ram. As far as I know, no filesystems support this natively. What can be done is to use dm-snapshot to create a snapshot of the block device with the cow file residing on a tmpfs. Then mount the snapshot device's filesystem as readonly. In this case the log will be replayed to ram. The caveat here is that, when in this state, the underlying block device should not be written to. So effectively the block device is locked up until the snapshot device is removed. A scenario where this might be an issue is as follows. You have a harddrive with isos on an ext4 filesystem that you use to grub iso loopback mount to boot from. When booting one of the isos, you use the snapshot setup with this filesystem because you don't know if its part of a hibernation image or not. When the livecd is up and running, you will not be able to modify the filesystem (you can write to it, but all changes are in ram and will be lost). That's as it should be if the filesystem is part of a hibernation image, but it might be more likely that its not. And in that case, it might be confusing why this restriction exists. What would be good is to have code that can detect if the system has a hibernation image or even better if the filesystem was mounted while a hibernation happened (not sure if that's possible). Then the snapshot work around could be done only when needed. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to the bug report. https://bugs.launchpad.net/bugs/41624 Title: Replaying journals of other OS's filesystems, by mounting them, is unsafe To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/iso-scan/+bug/41624/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
What we're going to end up with here in the installer is using grub- mount rather than mount, which guarantees a true read-only mount via GRUB's filesystem drivers plus FUSE. os-prober has already switched to this, and we'll switch the rest of the installer over as time permits. -- You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. https://bugs.launchpad.net/bugs/41624 Title: Replaying journals of other OS's filesystems, by mounting them, is unsafe -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
** Changed in: os-prober (Debian) Status: New = Fix Released -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
Closing this as won't fix. Upstream will not change this behavior and have their arguments for that. A deviation for Ubuntu is unmaintainable. The only way to prevent write access by Linux is to set the device access rights to read-only. ** Changed in: linux (Ubuntu) Status: Triaged = Won't Fix -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
Re: [Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
Ian Jackson wrote: You can say don't do that then but mount -o ro is exactly what every administrator reaches for in time of trouble, and they expect it to do no harm. That was exactly the point I argued on the LKML but they don't seem to see it that way. Maybe Ben Collins can try to knock this sense into them, or fix it for Ubuntu? -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
Re: [Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
Phillip Susi writes ([Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe): Which kernel you are using does not really matter because the linux kernel developers consider this to be working as intended. I have tried arguing with the on the LKML a few times with no success. They seem to think that the read only mount flag does not mean do not write to this disk but rather do not allow files to be opened for write access. Phillip is correct. If we want this fixed, we're going to have to fix it ourselves it looks like. I think we should do so. Just this week I was helping someone recover a machine which was already damaged at the time and was made worse when they typed mount -o ro /dev/mapper/volumegroup-logicalvolume-real /mnt which causes ext3 to write the journal back into the snapshotted volume bypassing the LVM system. You can say don't do that then but mount -o ro is exactly what every administrator reaches for in time of trouble, and they expect it to do no harm. Ian. -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
Which kernel you are using does not really matter because the linux kernel developers consider this to be working as intended. I have tried arguing with the on the LKML a few times with no success. They seem to think that the read only mount flag does not mean do not write to this disk but rather do not allow files to be opened for write access. If we want this fixed, we're going to have to fix it ourselves it looks like. -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
The Ubuntu Kernel Team is planning to move to the 2.6.27 kernel for the upcoming Intrepid Ibex 8.10 release. As a result, the kernel team would appreciate it if you could please test this newer 2.6.27 Ubuntu kernel. There are one of two ways you should be able to test: 1) If you are comfortable installing packages on your own, the linux- image-2.6.27-* package is currently available for you to install and test. --or-- 2) The upcoming Alpha5 for Intrepid Ibex 8.10 will contain this newer 2.6.27 Ubuntu kernel. Alpha5 is set to be released Thursday Sept 4. Please watch http://www.ubuntu.com/testing for Alpha5 to be announced. You should then be able to test via a LiveCD. Please let us know immediately if this newer 2.6.27 kernel resolves the bug reported here or if the issue remains. More importantly, please open a new bug report for each new bug/regression introduced by the 2.6.27 kernel and tag the bug report with 'linux-2.6.27'. Also, please specifically note if the issue does or does not appear in the 2.6.26 kernel. Thanks again, we really appreicate your help and feedback. ** Tags added: cft-2.6.27 -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
partman-basicfilesystems no longer automounts by default, as of Hardy, which takes care of that part of this bug: partman-basicfilesystems (56ubuntu4) hardy; urgency=low * Disable automounting unless partman/automount is preseeded to true. This makes LP #106209 much less likely to occur, since future installations are less likely to format a partition whose UUID we have in /etc/fstab. -- Colin Watson [EMAIL PROTECTED] Wed, 09 Apr 2008 08:18:47 +0100 ** Changed in: linux (Ubuntu) Sourcepackagename: linux-source-2.6.22 = linux ** Changed in: partman-basicfilesystems (Ubuntu) Assignee: (unassigned) = Colin Watson (kamion) Status: Confirmed = Fix Released -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
See also bug 230703. ** Also affects: iso-scan (Ubuntu) Importance: Undecided Status: New ** Changed in: iso-scan (Ubuntu) Importance: Undecided = High Status: New = Triaged ** Also affects: lupin (Ubuntu) Importance: Undecided Status: New ** Changed in: lupin (Ubuntu) Importance: Undecided = Low Status: New = Triaged -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
This definitely also affects iso-scan. lupin is affected in theory, but in practice I think it's quite unlikely that somebody will start Wubi and then hibernate Windows rather than simply rebooting. -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
... and of course the Wubi installation process really does require writing to the Windows filesystem, so the only thing that could be done in lupin would be to refuse to function at all. -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
Marking as Triaged since the report is complete. ** Changed in: linux-source-2.6.22 (Ubuntu) Status: Incomplete = Triaged -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
** Changed in: partman-basicfilesystems (Ubuntu) Assignee: Ian Jackson (ijackson) = (unassigned) -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
Exactly. If you do a read only mount of an inconsistent filesystem, you /expect/ to get inconsistent results from trying to read an inconsistent filesystem. The whole idea though, is that you make your best effort to access the data without modifying it and possibly causing more damage. Since the lkml seems to have their head in the sand on this one, what are the odds on Ubuntu diverging? -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
Marking the Gutsy-allocated part of this report Incomplete and assigning to kernel-team to remove it from the list of outstanding new/undecided bugs against Gutsy. Hopefully at some point a decision can be made over what to do with this, but it looks like as far as the kernel is concerned that might be a long way off, if at all. I've noted Phillip's comments in theLKML discussion thread on this at http://lkml.org/lkml/2007/4/8/97 ** Changed in: linux-source-2.6.22 (Ubuntu) Assignee: (unassigned) = Ubuntu Kernel Team Status: New = Incomplete -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
Re: [Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
TJ writes ([Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe): I've noted Phillip's comments in theLKML discussion thread on this at http://lkml.org/lkml/2007/4/8/97 Having read that thread, I'm deeply unimpressed by the head in the sand attitude displayed by some participants. Phillip Susi is of course absolutely right. Ian. -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
Ian, yes it does seem a bit pedantic although to be fair there was a devils-advocate stance :) I can see both arguments: On the one hand read-only should mean just that, it should have the same effect as read-only media. On the other hand a journalled file-system does need to replay the log to look consistent, even if it is only replayed to RAM. On balance, I'd say a read-only file-system shouldn't have the log file replayed (to RAM or disk) no matter if it appears inconsistent at that time. When the file-system is next mounted read-write (in this scenario, by the OS that 'owns' it) the file system will be consistent. -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
That sounds like an acceptable workaround but I still maintain that this is a kernel bug. Read only means you no touch. ** Also affects: linux-source-2.6.22 (Ubuntu) Importance: Undecided Status: New -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
** Changed in: os-prober (Debian) Status: Unknown = Unconfirmed -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
** Changed in: partman-basicfilesystems (Ubuntu) Assignee: (unassigned) = Ian Jackson -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
I would suggest teaching parted_server (in partman-base) about a new command to tell whether the fs on a given partition is dirty, and making use of that in partman-basicfilesystems where it decides whether to automount things. As far as os-prober goes, there was discussion about this recently upstream in http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=417407; there was a suggestion here to protect block devices by using 'blockdev --setro', which ought to convince the kernel not to do anything at all to the contents of the block device for the duration. I think this ought to require resurrecting the port we used to have of blockdev to busybox, rather than creating a new blockdev-udeb. ** Bug watch added: Debian Bug tracker #417407 http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=417407 ** Also affects: os-prober (Debian) via http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=417407 Importance: Unknown Status: Unknown -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://bugs.launchpad.net/bugs/41624 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 41624] Re: Replaying journals of other OS's filesystems, by mounting them, is unsafe
Sounds like this is a kernel bug then? Mounting a filesystem r/o should NEVER modify the disk. Should another bug be created for that and filed upstream? -- Replaying journals of other OS's filesystems, by mounting them, is unsafe https://launchpad.net/bugs/41624 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
