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From: Karolin Varner <karo@cupdev.net>
To: linux-fsdevel@vger.kernel.org
Subject: Proposal: Allow mounting and bind mounting over symlinks – flag to not expand symlinks
Date: Fri, 3 Sep 2021 23:39:23 +0200	[thread overview]
Message-ID: <e2fbd746-bc05-45e0-34e3-93963326ead6@cupdev.net> (raw)

Morning all!

I would like to propose adding a flag to the syscall underlying mount(2) that disables symlink expansion.

The motivating use case for this is as follows: I am trying to set up a netns namespace that requires a specific DNS setup,
to this end, I am creating a mount namespace and replacing /etc/resolve.conf. Unfortunately, resolv.conf is a symlink provided
by systemd-resolved. Bind mounting over said file with my replacement is impossible: With `-c` option, the `mount` command
actually targets `/etc/resolv.conf` instead of the file it's pointing to, but the kernel expands it internally and seems to
mount over the file being pointed to.

I highly similar use cases exist.

I have tried the nosymfollow option, which did not work. I think it affects only how symlinks are handled once the fs
is mounted.

Best,
Karolin Varner

                 reply	other threads:[~2021-09-03 21:45 UTC|newest]

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