erofs-snapshotter: protect layer blobs with FS_IMMUTABLE_FL #11431
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
hsiangkao
force-pushed
the
erofs-snapshotter
branch
from
0efcc32 to
fffcc32
Compare
|
|
7 tasks
fuweid
reviewed
Feb 25, 2025
| @@ -507,6 +535,8 @@ func (s *snapshotter) Remove(ctx context.Context, key string) (err error) { | |||
| if err != nil { | |||
| return fmt.Errorf("unable to get directories for removal: %w", err) | |||
| } | |||
| // Clear IMMUTABLE_FL before removal, since this flag avoids it. | |||
| _ = setImmutable(s.layerBlobPath(id), false) | |||
There was a problem hiding this comment.
I think we should return this error here.
There was a problem hiding this comment.
Yeah, will fix later.
I once thought administers manually house-keeping or unsupported fs use cases or lack of CAP_LINUX_IMMUTABLE due to MAC restriction.
But since setImmutable won't SETFLAGS if (GETFLAG & FS_IMMUTABLE_FL == 0), I'm fine with it now.
There was a problem hiding this comment.
Fixed, thanks for your comment!
As documented in ioctl_iflags(2):
```
FS_IMMUTABLE_FL
The file is immutable: no changes are permitted to the file contents
or metadata (permissions, timestamps, ownership, link count, and so
on). (This restriction applies even to the superuser.)
```
For example, any user cannot delete/move layer blobs when
FS_IMMUTABLE_FL is set:
``` sh
# cd /var/lib/containerd/io.containerd.snapshotter.v1.erofs/snapshots/4
# mv layer{,1}.erofs
mv: cannot move 'layer.erofs' to 'layer1.erofs': Operation not permitted
# rm layer.erofs
rm: cannot remove 'layer.erofs': Operation not permitted
```
Note that it's a best-effort approach for data loss prevention. IOWs,
just warn out if FS_IMMUTABLE_FL cannot be set anyway (e.g., due to lack
of support in the underlying filesystem.)
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
hsiangkao
force-pushed
the
erofs-snapshotter
branch
from
fffcc32 to
5fa6ddd
Compare
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
As documented in ioctl_iflags(2):
For example, any user cannot delete/move layer blobs when FS_IMMUTABLE_FL is set:
Note that it's a best-effort approach for data loss prevention(e.g. #10655). IOWs, just warn out if FS_IMMUTABLE_FL cannot be set anyway (e.g., due to lack of support in the underlying filesystem.)