[Bug]: Permission denied syncing "read only" shared folders

[masakkre]

⚠️ Before submitting, please verify the following: ⚠️

• This is a bug, not a question or a configuration issue.
• This issue is not already reported on Github (I've searched it).
• Nextcloud Server and Desktop Client are up to date. See Server Maintenance and Release Schedule and Desktop Releases for supported versions.
• I agree to follow Nextcloud's Code of Conduct

Bug description

Good morning,

I will try to organize the topic with the information:

Although at first I thought the permission denied sync error was caused by file names containing Ñ or accented characters, I have discovered that it has nothing to do with that. It happens regardless of whether the file or folder names are normal.

I believe the problem lies in how the sync client handles shared folders that have read-only permissions. For example:

2.1. User A shares a folder and its contents with User B or a group of users, assigning read-only permissions to that folder and disabling the options to create, modify, or delete. It does not matter whether this is done from the Nextcloud web interface or from their synced folder.

2.2. The clients of User B or the user group create the shared folder, but afterward they are unable to sync its contents, showing a permission denied error.

2.3. I have also discovered that if this folder was syncing correctly in previous versions that did not have this problem, and I update to the latest version (4.0.6), if a conflict appears in any file, trying to resolve it by asking the application to keep the server version does not work, and it behaves as if it cannot take any action.

3. I can solve all these problems if I change the permissions of the shared folder using chmod -R 755 /path/folder.

4. I have also discovered that the same thing happens on Windows clients, not only on Linux/Debian clients.

I know that at first I blamed the problem on file names, since the first issues I encountered involved names containing Ñ or accents. However, over time I noticed that the problems increased and were unrelated to file names. Finally, it seems that the issue is caused by the permissions of the local folder when it is created by the application if that folder is a shared folder with read-only permissions, as I explained above. On the web interface, I do not have any problems with these folders; it only happens during synchronization.

I hope I have explained myself more clearly. If you need more information, please do not hesitate to ask, and I will try to provide everything I can.

Thank you very much for your patience.

Steps to reproduce

1. User A share a folder in nextcloud with read-only permissions. (no modification, creation or delete permissions)
2. User B syncs this folder with the app. The app creates this folder, but can not create the files, giving permission denied error
3. in linux, using chmod -R 755 /path/read-only-shared-folder fixes this error
4. In windows, syncing in normal mode (no virtual folders), i am having same error, but i can not fix it.
5. I have probe with fresh install and updated installs. In previous versions of sync app, i have not this problem (version 3.X)
   ...

Expected behavior

When clicking on the share dialog, share by e-mail should be an option.
...

Which files are affected by this bug

syncing shared folder with read only permissions

Operating system

Linux

Which version of the operating system you are running.

ubuntu 22.04, windows 11

Package

Official PPA

Nextcloud Server version

31.0.8

Nextcloud Desktop Client version

4.0.6

Is this bug present after an update or on a fresh install?

Fresh desktop client install

Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

Are you using an external user-backend?

• Default internal user-backend
• LDAP/ Active Directory
• SSO - SAML
• Other

Nextcloud Server logs

Additional info

No response

[kuihlein]

+1

I seem to have the same issue. But I am on macOS.

After updating the local permissions with chmod -R 755 /path/read-only-shared-folder. I got the message "Not allowed to upload this file because it is read-only on the server, restoring" by the client. Although the web interface shows, that I have all permissions for the file.

Desktop Client: 4.0.6
Server version: 32.0.6