Hi list, (Preemptive note: this was with btrfs-progs 4.15.1, I have since upgraded to 4.17. My kernel version is 4.14.52-gentoo.)
I recently had to restore the root FS of my desktop from backup (extent tree
corruption; not sure how, possibly a loose SATA cable?). Everything was fine,
even if restoring was slower than expected. However, I encountered two files
with permission problems, namely:
- /bin/ping, which caused running ping as a normal user to fail due to missing
permissions, and
- /sbin/unix_chkpwd (part of PAM), which prevented me from unlocking the KDE
Plasma lock screen; I needed to log into a TTY and run "loginctl unlock-
session".
Both were easily fixed by reinstalling the affected packages (iputils and
pam), but I wonder why this happened after restoring from backup.
I originally thought it was related to the SUID bit not being set, because of
the explanation in the ping(8) man page (section "SECURITY"), but cannot find
evidence of that -- that is, after reinstallation, "ls -lh" does not show the
sticky bit being set, or any other special permission bits, for that matter:
% ls -lh /bin/ping /sbin/unix_chkpwd
-rwx--x--x 1 root root 60K 22. Jul 14:47 /bin/ping*
-rwx--x--x 1 root root 31K 23. Jul 00:21 /sbin/unix_chkpwd*
(Note: no ACLs are set, either.)
I do remember the qcheck program (a Gentoo-specific program that checks the
integrity of installed packages) complaining about wrong file permissions, but
I didn't save its output, and there's a chance it *might* have been because I
ran qcheck without root permissions :-/ .
I vaguely remember some patches and/or discussion regarding permission
transfer issues with send/receive on this ML, but didn't find anything after
searching through my Email archive, so I might be misremembering.
Does anybody have any idea what possibly went wrong, or any similar experience
to speak of?
Greetings
--
Marc Joliet
--
"People who think they know everything really annoy those of us who know we
don't" - Bjarne Stroustrup
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