setcifsacl: fix adding ACE when owner sid in unexpected location

[Rakesh Ginjupalli]

For Bionic release, current cifs-utils package version is 6.8-1. This version is missing an ACL tools fix that is needed for Azure xSMB.

Commit in question which needs to be backported: 0feb1a80f3777f4c244b46958aa9f730de9e18b6 setcifsacl: fix adding ACE when owner sid in unexpected location

[Impact]

 * The bug shows up with mounted cifs/smb filesystem, when a user tries to modify the DACL for the files/directories in the mount. If the owner/group ACEs do not appear first in the DACL (happens quite easily with Azure file shares). The setcifsacl command in cifs-utils fails in that case:

$ setcifsacl -a ‘ACL:MYDOMAIN\domuser:DENIED/0x0/FULL’ /mnt/test/abc
main: setxattr error: Invalid argument

 * With the fix available in commit 0feb1a80f3777f4c244b46958aa9f730de9e18b6, the above error is not returned, and the command works.

[Regression potential]

The fix has been created by Microsoft and approved by cifs-utils upstream maintainers.

The fix has been tested in ubuntu (a test package I have built in a ppa) pre-SRU by Microsoft/Azure themselves, and they confirm everything is working as expected with this fix using the test case above.

The fix is found in Ubuntu with Eoan and onwards.

[Other information]

# Upstream commit:
https://git.samba.org/?p=cifs-utils.git;a=commit;h=0feb1a80f3777f4c244b46958aa9f730de9e18b6

# git describe --contains 0feb1a80f3777f4c244b46958aa9f730de9e18b6
cifs-utils-6.9~14

# rmadison
 => cifs-utils | 2:6.8-1 | bionic
 cifs-utils | 2:6.9-1 | focal
 cifs-utils | 2:6.10-0ubuntu1 | groovy |

[Eric Desrochers (slashd)]

Uploaded in Bionic/18.04LTS.

It is now waiting for SRU team approval for the package to start building in bionic-proposed pocket for its testing/verification phase.

Regards,
Eric

[Łukasz Zemczak (sil2100)]

Hello Rakesh, or anyone else affected,

Accepted cifs-utils into bionic-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/cifs-utils/2:6.8-1ubuntu1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-bionic to verification-done-bionic. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-bionic. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Łukasz Zemczak (sil2100)]

So I understand running `setcifsacl -a ‘ACL:MYDOMAIN\domuser:DENIED/0x0/FULL’ /mnt/test/abc` on a mounted cifs, while on an affected system? I assume it is easy to do with Azure file shares, but I'd also appreciate a bit more details about the testing needed to be done for verification. Could you update the description to include that missing information?

Anyway, this upload looks fine so I will approve it.

[nspmangalore (nspmangalore)]

I've verified the cifs-utils in bionic-proposed. It works.
I'll review the bug description and add as much details as I can.

[nspmangalore (nspmangalore)]

The version tested was cifs-utils 2:6.8-1ubuntu1.
Testing the fix involved mounting Azure file share from Ubuntu-18.04, create a file, then:
getcifsacl filename

Add a valid ACE which is not already a part of the above output.
setcifsacl -a ‘ACL:MYDOMAIN\domuser:DENIED/0x0/FULL' filename

And just for safe measure, removed and created the ACE again.
setcifsacl -D ‘ACL:MYDOMAIN\domuser:DENIED/0x0/FULL' filename
setcifsacl -a ‘ACL:MYDOMAIN\domuser:DENIED/0x0/FULL' filename

The above goes through without any error, which was not true without the fix.

Without the fix, I get this error:
setcifsacl -a ‘ACL:MYDOMAIN\domuser:DENIED/0x0/FULL’ /mnt/test/abc
main: setxattr error: Invalid argument

[Eric Desrochers (slashd)]

Thanks for your testing nspmangalore, much appreciated !

[Eric Desrochers (slashd)]

The release of 'cifs-utils' is likely to happen only next week.

As stated in the SRU policy guide :
"Please note that SRUs will not be published to the -updates pocket on Friday (or Saturday or Sunday). Any exception will need justification."

Let's circle back beginning of next week for its release.

- Eric

[Launchpad Janitor (janitor)]

This bug was fixed in the package cifs-utils - 2:6.8-1ubuntu1

---------------
cifs-utils (2:6.8-1ubuntu1) bionic; urgency=medium

  * d/p/setcifsacl-fix-adding-ACE-when-owner-sid-in-unexpect.patch:
    Fix adding ACE when owner sid in unexpected location (LP: #1886548)

 -- Eric Desrochers <email address hidden> Wed, 08 Jul 2020 17:44:31 +0000

[Łukasz Zemczak (sil2100)]

The verification of the Stable Release Update for cifs-utils has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.