All, This likely isn't unique to Debian, much less the alpha platform, but I first encountered this strangeness on my alpha running Debian unstable.
Best way to explain what I'm seeing is by example. A fairly common thing to do is create temporary or download directories with octal mode 1777 that are accessible by everyone. The directory can be read/written by everyone, but users (with the exception of "root") cannot delete files in the directory that they do not own. Otherwise, normal file permissions are applied as far as operations that can be performed on a particular file, and the expected (pre-libc6 update) behavior is that "root" can do anything with a particular file in the absence of extended ACL or selinux interference. "/var/tmp" is one such directory, and a thing I like to do is maintain a list of currently-installed packages by running "dpkg -l > packages" in that directory as a normal user. Prior to the libc6 update, "root" could update that file with an editor or by running the same "dpkg -l > packages" command. After the libc6 update, "root" can't do anything with the file except delete it. The file's owner is the only user that can update it, EVEN IF THE FILE PERMISSIONS ALLOW WRITING BY EVERYONE. Even more odd: "root" can change the permissions on the file to, say, "-rw-rw-rw-", and STILL cannot update the file. Outside of the directory having the sticky bit set, "root" can still do anything/everything to another user's files as expected. I'm currently running an up-to-date "unstable" distro. Kernel version is 5.5.0, and libc6 is "libc6.1:alpha 2.30-4". Maybe the rules have changed. If so, a pointer to the relevant documentation would be appreciated. Thanks. --Bob
