Hi, Quoting Helmut Grohne (2024-01-12 21:58:00) > > What can cause mkfs.ext4 to fail with a "Permission denied" error? > I think this is our typical problem when dealing with user namespaces. I > guess that the thing that fails here is mkfs.ext4 opening the target image > file (to be formatted). That file has earlier been chowned to the root uid > inside the namespace, so permission should be there, but you need more. You > also need execute permission (to the first uid of your namespace) for the > containing directory up until the root. I guess that none of those are > world-executable and not by chanced owned by your first subuid nor owned by > the first group in your subgid range.
I'm not yet convinced that this is it. The problem occurs for Francesco when
using either /tmp or /dev/shm as a temporary directly. By default, those two
locations should have the desired permission bits set. Lets check whether
world-execute permissions are set for all directories up until root. I have
this:
$ stat -c "%a %n" / /dev /dev/shm /tmp
755 /
755 /dev
1777 /dev/shm
1777 /tmp
Francesco, what are the world execute permissions on all path components up to
/tmp and /devv/shm in your case?
Arguably, mmdebstrap maybe should do this check at start-up. To have a
real-world test-case for such a feature, I'm eager to see how Francesco's
system looks like.
Thanks!
cheers, josch
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