From: miaoxie@huawei.com (Miao Xie)
Subject: [PATCH] erofs: move erofs out of staging
Date: Tue, 20 Aug 2019 11:33:51 +0800 [thread overview]
Message-ID: <698e2fa6-956b-b367-6f6a-3e6b09bfef5f@huawei.com> (raw)
In-Reply-To: <bdb91cbf-985b-5a2c-6019-560b79739431@gmx.com>
on 2019/8/20@8:55, Qu Wenruo wrote:
> [...]
>>>> I have made a simple fuzzer to inject messy in inode metadata,
>>>> dir data, compressed indexes and super block,
>>>> https://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs-utils.git/commit/?h=experimental-fuzzer
>>>>
>>>> I am testing with some given dirs and the following script.
>>>> Does it look reasonable?
>>>>
>>>> # !/bin/bash
>>>>
>>>> mkdir -p mntdir
>>>>
>>>> for ((i=0; i<1000; ++i)); do
>>>> mkfs/mkfs.erofs -F$i testdir_fsl.fuzz.img testdir_fsl > /dev/null 2>&1
>>>
>>> mkfs fuzzes the image? Er....
>>
>> Thanks for your reply.
>>
>> First, This is just the first step of erofs fuzzer I wrote yesterday night...
>>
>>>
>>> Over in XFS land we have an xfs debugging tool (xfs_db) that knows how
>>> to dump (and write!) most every field of every metadata type. This
>>> makes it fairly easy to write systematic level 0 fuzzing tests that
>>> check how well the filesystem reacts to garbage data (zeroing,
>>> randomizing, oneing, adding and subtracting small integers) in a field.
>>> (It also knows how to trash entire blocks.)
>
> The same tool exists for btrfs, although lacks the write ability, but
> that dump is more comprehensive and a great tool to learn the on-disk
> format.
>
>
> And for the fuzzing defending part, just a few kernel releases ago,
> there is none for btrfs, and now we have a full static verification
> layer to cover (almost) all on-disk data at read and write time.
> (Along with enhanced runtime check)
>
> We have covered from vague values inside tree blocks and invalid/missing
> cross-ref find at runtime.
>
> Currently the two layered check works pretty fine (well, sometimes too
> good to detect older, improper behaved kernel).
> - Tree blocks with vague data just get rejected by verification layer
> So that all members should fit on-disk format, from alignment to
> generation to inode mode.
>
> The error will trigger a good enough (TM) error message for developer
> to read, and if we have other copies, we retry other copies just as
> we hit a bad copy.
>
> - At runtime, we have much less to check
> Only cross-ref related things can be wrong now. since everything
> inside a single tree block has already be checked.
>
> In fact, from my respect of view, such read time check should be there
> from the very beginning.
> It acts kinda of a on-disk format spec. (In fact, by implementing the
> verification layer itself, it already exposes a lot of btrfs design
> trade-offs)
>
> Even for a fs as complex (buggy) as btrfs, we only take 1K lines to
> implement the verification layer.
> So I'd like to see every new mainlined fs to have such ability.
It is a good idea. In fact, we already have a verification layer which was implemented
as a device mapper sub-module. I think it is enough for a read-only filesystem because
it is simple, flexible and independent(we can modify the filesystem layout without
verification module modification).
>>
>> Actually, compared with XFS, EROFS has rather simple on-disk format.
>> What we inject one time is quite deterministic.
>>
>> The first step just purposely writes some random fuzzed data to
>> the base inode metadata, compressed indexes, or dir data field
>> (one round one field) to make it validity and coverability.
>>
>>>
>>> You might want to write such a debugging tool for erofs so that you can
>>> take apart crashed images to get a better idea of what went wrong, and
>>> to write easy fuzzing tests.
>>
>> Yes, we will do such a debugging tool of course. Actually Li Guifu is now
>> developping a erofs-fuse to support old linux versions or other OSes for
>> archiveing only use, we will base on that code to develop a better fuzzer
>> tool as well.
>
> Personally speaking, debugging tool is way more important than a running
> kernel module/fuse.
> It's human trying to write the code, most of time is spent educating
> code readers, thus debugging tool is way more important than dead cold code.
Agree, Xiang and I have no time to developing this feature now, we are glad very much if you could help
us to do it ;)
Thanks
Miao
>
> Thanks,
> Qu
>>
>> Thanks,
>> Gao Xiang
>>
>>>
>>> --D
>>>
>>>> umount mntdir
>>>> mount -t erofs -o loop testdir_fsl.fuzz.img mntdir
>>>> for j in `find mntdir -type f`; do
>>>> md5sum $j > /dev/null
>>>> done
>>>> done
>>>>
>>>> Thanks,
>>>> Gao Xiang
>>>>
>>>>>
>>>>> Thanks,
>>>>> Gao Xiang
>>>>>
>
next prev parent reply other threads:[~2019-08-20 3:33 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-17 8:23 [PATCH] erofs: move erofs out of staging Gao Xiang
2019-08-17 21:19 ` Richard Weinberger
2019-08-17 22:07 ` Gao Xiang
2019-08-17 23:25 ` Richard Weinberger
2019-08-17 23:38 ` Gao Xiang
2019-08-18 0:04 ` Gao Xiang
2019-08-18 0:52 ` Gao Xiang
2019-08-18 8:16 ` Richard Weinberger
2019-08-18 8:45 ` Gao Xiang
2019-08-18 9:03 ` Richard Weinberger
2019-08-18 9:09 ` Greg Kroah-Hartman
2019-08-18 9:21 ` Richard Weinberger
2019-08-18 10:12 ` Chao Yu
2019-08-18 15:11 ` Theodore Y. Ts'o
2019-08-18 15:58 ` Christoph Hellwig
2019-08-18 16:16 ` Eric Biggers
2019-08-18 16:22 ` Christoph Hellwig
2019-08-18 16:33 ` Gao Xiang
2019-08-18 17:29 ` Eric Biggers
2019-08-18 17:47 ` Christoph Hellwig
2019-08-18 18:16 ` Gao Xiang
2019-08-18 20:14 ` Gao Xiang
2019-08-19 7:35 ` Richard Weinberger
2019-08-19 8:02 ` Gao Xiang
2019-08-19 10:34 ` [PATCH 0/6] staging: erofs: first stage of corrupted compressed images Gao Xiang
2019-08-19 10:34 ` [PATCH 1/6] staging: erofs: some compressed cluster should be submitted for corrupted images Gao Xiang
2019-08-19 14:36 ` Chao Yu
2019-08-19 14:39 ` Chao Yu
2019-08-19 10:34 ` [PATCH 2/6] staging: erofs: cannot set EROFS_V_Z_INITED_BIT if fill_inode_lazy fails Gao Xiang
2019-08-19 14:43 ` Chao Yu
2019-08-19 10:34 ` [PATCH 3/6] staging: erofs: add two missing erofs_workgroup_put for corrupted images Gao Xiang
2019-08-19 14:40 ` Chao Yu
2019-08-19 10:34 ` [PATCH 4/6] staging: erofs: avoid loop in submit chains Gao Xiang
2019-08-19 14:50 ` Chao Yu
2019-08-19 10:34 ` [PATCH 5/6] staging: erofs: detect potential multiref due to corrupted images Gao Xiang
2019-08-19 14:57 ` Chao Yu
2019-08-21 2:19 ` Greg Kroah-Hartman
2019-08-19 10:34 ` [PATCH 6/6] staging: erofs: avoid endless loop of invalid lookback distance 0 Gao Xiang
2019-08-19 14:58 ` Chao Yu
2019-08-19 16:09 ` [PATCH] erofs: move erofs out of staging Darrick J. Wong
2019-08-19 20:30 ` Gao Xiang
2019-08-20 0:55 ` Qu Wenruo
2019-08-20 1:55 ` Gao Xiang
2019-08-20 2:24 ` Chao Yu
2019-08-20 2:38 ` Qu Wenruo
2019-08-20 7:15 ` Chao Yu
2019-08-20 8:46 ` Qu Wenruo
2019-08-21 2:12 ` Chao Yu
2019-08-20 15:56 ` Theodore Y. Ts'o
2019-08-20 16:35 ` Gao Xiang
2019-08-21 0:51 ` Theodore Y. Ts'o
2019-08-21 1:34 ` Chao Yu
2019-08-21 1:48 ` Darrick J. Wong
2019-08-21 1:57 ` Chao Yu
2019-08-20 3:33 ` Miao Xie [this message]
2019-08-20 3:46 ` Gao Xiang
2019-08-20 6:04 ` Qu Wenruo
2019-08-20 6:22 ` Gao Xiang
2019-08-19 7:37 ` Richard Weinberger
2019-08-18 17:43 ` Theodore Y. Ts'o
2019-08-18 16:03 ` Gao Xiang
2019-08-18 17:06 ` Richard Weinberger
2019-08-18 17:46 ` Theodore Y. Ts'o
2019-08-18 18:00 ` Richard Weinberger
2019-08-18 18:31 ` Gao Xiang
2019-08-18 9:28 ` Gao Xiang
2019-08-19 5:28 ` [PATCH] erofs: Use common kernel logging style Joe Perches
2019-08-19 5:52 ` Gao Xiang
2019-08-19 5:47 ` Joe Perches
2019-08-19 6:08 ` Gao Xiang
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