overlayfs: copy up i_uid/i_gid from the underlying inode
YAMA et al rely on on i_uid/i_gid to be populated in order to perform
their checks. While these really cannot be guarenteed as the underlying
filesystem may not even have the concept, they are expected to be filled
when possible. To quote Al Viro:
"Ideally, yes, we'd want to have ->i_uid used only by fs-specific
code and helpers used by that fs (including those that are
implicit defaults). [...] In practice we have enough places
where uid/gid is used directly to make setting them practically
a requirement - places like /proc/<pid>/ can get away with
not doing that, but only because shitloads of syscalls are
not allowed on those anyway, permissions or no permissions.
In anything general-purpose you really need to set it."
Copy up the underlying filesystem information into the overlayfs inode
when we create it.
BugLink: http://bugs.launchpad.net/bugs/944386
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
4 files changed
