Hi,
we have few tests which uses `umount /sys/fs/selinux` trick to check how
userspace works in SELinux "disabled" environment. But it's not possible
with the current master:
# umount /sys/fs/selinux
umount: /sys/fs/selinux: target is busy.
# lsof /sys/fs/selinux
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
systemd 1 root mem REG 0,21 0 19 /sys/fs/selinux/status
systemd 1 root 55r REG 0,21 0 19 /sys/fs/selinux/status
systemd-u 875 root mem REG 0,21 0 19 /sys/fs/selinux/status
systemd-u 875 root 6r REG 0,21 0 19 /sys/fs/selinux/status
dbus-brok 1116 dbus mem REG 0,21 0 19 /sys/fs/selinux/status
dbus-brok 1116 dbus 5r REG 0,21 0 19 /sys/fs/selinux/status
systemd-l 1134 root mem REG 0,21 0 19 /sys/fs/selinux/status
systemd-l 1134 root 4r REG 0,21 0 19 /sys/fs/selinux/status
systemd 1643 root mem REG 0,21 0 19 /sys/fs/selinux/status
systemd 1643 root 28r REG 0,21 0 19 /sys/fs/selinux/status
(sd-pam) 1645 root mem REG 0,21 0 19 /sys/fs/selinux/status
...
sshd 218874 root mem REG 0,21 0 19 /sys/fs/selinux/status
sshd 218874 root 3r REG 0,21 0 19 /sys/fs/selinux/status
sshd 218880 plautrba mem REG 0,21 0 19 /sys/fs/selinux/status
sshd 218880 plautrba 3r REG 0,21 0 19 /sys/fs/selinux/status
It seems to be caused by commit 05bdc03130d7 ("libselinux: use kernel
status page by default") which replaced avc_netlink_open() in
avc_init_internal() with selinux_status_open()
In case of sshd process, /sys/fs/selinux/status seems to be mapped by
selinux_check_access() which is called from pam_selinux and it's left
open as there's no selinux_status_close() in selinux_check_access().
The similar situations probably happen in systemd and dbus.
So is it expected? Is it a bug? Do we need to change other components so
that they would call selinux_status_close() when they use check access?
Petr
