smbc_opendir returns EEXIST if login credentials are incorrect, breaking SMB shares in Kodi

[roothorick]

[Impact]

A regression in Samba causes the wrong error message to be returned on an unsuccessful login, returning EEXIST instead of EACCESS or EPERM.

[Tese Case]

# lxc launch ubuntu:bionic tester && lxc exec tester bash
# apt update && apt dist-upgrade -y && apt install -y samba gvfs libglib2.0-bin gvfs-bin gvfs-backends dbus-x11 &&
echo "
[global]
workgroup = WORKGROUP
security = user
map to guest = bad user
[test]
    path = /tmp
    browseable = yes
    read only = yes
    valid users = someone
" >/etc/samba/smb.conf &&
service smbd restart
# su - -c "dbus-launch gio mount -a smb://localhost/test" ubuntu
gio: smb://localhost/test/: Failed to mount Windows share: File exists

[Regression Potential]

The change reverts a regression in the closing order in certain cases from a previous version of samba, and should not cause further regressions in the fix.

[Original Description]

Target to milestone
​ Bionic Remove
Triaged

High

  Karl Stenerud

Target to milestone
Also affects project (?) Also affects distribution/package Nominate for series
Edit
Bug Description

In Kodi, try to add a smb:// URL for a share that doesn't allow guest logins and you'll get a cryptic "File Exists" error. It never asks for login credentials. From online searching, this is most likely due to a bug in libsmbclient where smbc_opendir will return EEXIST instead of a more appropriate error code if invalid login credentials were provided.

This was fixed in Samba 4.8:

https://github.com/samba-team/samba/commit/7470b9b18af282a742929d3fc90f4be5520428a1

But 18.04 is shipping 4.7.

Trying to add a share where the hostname doesn't resolve results in some cryptic messages as well, but that may or may not be a different bug.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: libsmbclient 2:4.7.6+dfsg~ubuntu-0ubuntu2.2
ProcVersionSignature: Ubuntu 4.15.0-38.41-generic 4.15.18
Uname: Linux 4.15.0-38-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.9-0ubuntu7.4
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Thu Nov 1 21:15:29 2018
InstallationDate: Installed on 2018-09-12 (51 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
RelatedPackageVersions:
 nautilus 1:3.26.4-0~ubuntu18.04.2
 gvfs 1.36.1-0ubuntu1.1
SambaClientRegression: Yes
SourcePackage: samba
UpgradeStatus: No upgrade log present (probably fresh install)

[roothorick (8-roothorick-gmail-com)]

Found a workaround: Enter the username and password as part of the URL when adding the source. That is:

smb://<username>:<password>@<host>/<folder>/

This isn't really acceptable, as it means the password is plainly visible onscreen as you're setting up the share.

[Robie Basak (racb)]

Thank you for reporting this bug and helping to make Ubuntu better.

Cosmic is on 4.8 so this presumably affects Bionic only.

[Timo Aaltonen (tjaalton)]

Hello Ben, or anyone else affected,

Accepted samba into bionic-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/samba/2:4.7.6+dfsg~ubuntu-0ubuntu2.6 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 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.

[Karl Stenerud (kstenerud)]

Verified fixed

[Łukasz Zemczak (sil2100)]

Which package version has been used for verification?

[Karl Stenerud (kstenerud)]

samba 2:4.7.6+dfsg~ubuntu-0ubuntu2.6 (https://launchpad.net/ubuntu/+source/samba/2:4.7.6+dfsg~ubuntu-0ubuntu2.6) in the proposed pocket was used for verification.

Follow the testing steps in https://code.launchpad.net/~kstenerud/ubuntu/+source/samba/+git/samba/+merge/359602 except instead of adding the PPA, add the sources list entry:

deb http://archive.ubuntu.com/ubuntu bionic-proposed main

[Brian Murray (brian-murray)]

The verification of the Stable Release Update for samba has completed successfully and the package has now been 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.

[Launchpad Janitor (janitor)]

This bug was fixed in the package samba - 2:4.7.6+dfsg~ubuntu-0ubuntu2.6

---------------
samba (2:4.7.6+dfsg~ubuntu-0ubuntu2.6) bionic; urgency=medium

  * d/p/auth-fail-eexist.diff: smbc_opendir should not return EEXIST with
    invalid login credentials. Thanks to David Mulder. (LP: #1801227)

 -- Karl Stenerud <email address hidden> Fri, 23 Nov 2018 15:58:41 +0100