| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Fri, 17 Jan 2014 12:58:19 -0800 From: "Darrick J. Wong" <darrick.wong@...cle.com> To: Oleksij Rempel <linux@...pel-privat.de> Cc: linux-ext4@...r.kernel.org Subject: Re: What is status of metadata_csum On Fri, Jan 17, 2014 at 09:13:11PM +0100, Oleksij Rempel wrote: > Am 17.01.2014 20:21, schrieb Darrick J. Wong: > > On Fri, Jan 17, 2014 at 11:39:07AM +0100, Oleksij Rempel wrote: > >> Am 17.01.2014 09:18, schrieb Oleksij Rempel: > >>> Am 17.01.2014 03:00, schrieb Darrick J. Wong: > >>>> On Thu, Jan 16, 2014 at 11:57:20AM +0100, Oleksij Rempel wrote: > >>>>> What is metadata_csum status? > >>>>> > >>>>> i see there are benchmark updates on wiki page, but no updates for > >>>>> e2fsprogs. 1.43-WIP seems to be really old. > >>>> > >>>> Still waiting for 1.43. I don't know if there are early adopters running > >>>> 1.43-WIP without complaint, or if simply nobody's using it at all. :/ > >>> > >>> I didn't tested current master.git - my bad. It is not outdated :) > >>> > >>> Beside, the wiki should be corrected. If you enable 64bit, it will need > >>> extents too. > >>> > >>> Are there any existing tools for error injection for file systems? > >>> Random read error from libata or silent data corruptions? > >>> > >> > >> I was playing with metadata_csum trying to kill my system and now i have > >> some questions: > >> > >> first the test: > >> #find block number > >> sudo ./debugfs/debugfs -R "imap <3991825>" /dev/sdf1 > >> > >> #copy block > >> sudo dd if=/dev/sdf1 bs=4K count=1 skip=15958163 of=corrupt_block.bin > >> > >> #change one byte > >> ghex corrupt_block.bin > >> > >> #kill inode > >> sudo dd of=/dev/sdf1 bs=4K count=1 seek=15958163 if=corrupt_block.bin > >> > >> sudo ./debugfs/debugfs -R "stat <3991825>" /dev/sdf1 > >> #stat: Inode checksum does not match inode while reading inode 3991825 > >> > >> so, inode is corrupt: > >> - ext4 can detect inode corruption. Great work! I like it :) > >> - in this case file will not be shown by Nautilus. > >> - ls will show some thing like this: > >> > >> 4130898 drwx------ 8 oleksij oleksij 4096 Jan 17 09:31 Bilder > >> ? -????????? ? ? ? ? ? > >> ich-einfach_unverbesserlich_2.mkv > >> 3991826 -rw-rw-r-- 1 oleksij oleksij 622038707 Jan 17 11:12 igor.mkv > >> 3989506 drwxr-xr-x 26 oleksij oleksij 4096 Okt 9 23:11 linux > >> > >> it means, i know there is some thing wrong, but i do not know which inode > > > > Unfortunately, either the whole stat call succeeds or it doesn't. Your best > > bet to find the inode is: > > debugfs -n -R 'stat /path/within/fs' /dev/sdXXX > > Ok, looks like user space apps should handle errors in different whey. I > mean some thing like, show notification about probable FS errors and so on. AIX has ECORRUPT; maybe we should define that for the kernel/glibc? > >> - If fs is not fixed, file is lost? are blocks still allocated to this > >> inode? > > > > Yes, the blocks are still allocated. > > > >> - debufs will not allow me to edit inode corrupt inode. > > > > debugfs -n (disables checksum verification) > > > >> - If i run fsck -y file is lost. Most user wont be able to recover it. > > > > If you answer 'n' to the first prompt about the checksum failure, e2fsck will > > check the rest of the inode. If no other problems are found, it'll ask to > > correct the checksum. > > > > I've wondered if perhaps e2fsck ought to do something like this when there's a > > checksum problem: > > > > 1. If the user didn't prohibit clearing the inode as the first potential > > action, ask if e2fsck should just clear the inode. > > 2. If not, run the regular checks. > > 3. If there's still a checksum error, ask to fix the checksum. > > 4. If the user doesn't want to fix it, ask to clear the inode. > > sounds good. > > > iow, e2fsck --verify-checksums-last /dev/sdXX > > this mean? It would be a new flag to change the fsck behavior. > PS: More testing results from today. GRUB fails to install if > metadata_csum enabled. Should it be reported to GRUB devs? Yes, please report the bug to them. metadata_csum is a ROCOMPAT feature, which means that grub will need to learn about checksums if it wants to do anything other than rewrites of existing file blocks. --D -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists