Re: [libvirt] [PATCH] apparmor: allow qemu abstraction to read /proc/pid/cmdline

On 12/01/2017 02:26 PM, Jamie Strandboge wrote: > On Thu, 2017-11-30 at 10:43 -0700, Jim Fehlig wrote: >> Noticed the following denial in audit.log when shutting down >> an apparmor confined domain >> >> type=AVC msg=audit(1512002299.742:131): apparmor="DENIED" >> operation="open" profile="libvirt-66154842-e926-4f92-92f0- >> 1c1bf61dd1ff" >> name="/proc/1475/cmdline" pid=2958 comm="qemu-system-x86" >> requested_mask="r" denied_mask="r" fsuid=469 ouid=0 >> >> Squelch the denial by allowing read access to /proc/<pid>/cmdline. >> >> Signed-off-by: Jim Fehlig <jfehlig(a)suse.com&gt; >> --- >> >> Note: In the audit.log snippet, PID 1475 is libvirtd and 2958 is the >> qemu process. I must admit it is not clear to me why >> /proc/<libvirtd-pid>/cmdline is read on domain shutdown. >> >> examples/apparmor/libvirt-qemu | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/examples/apparmor/libvirt-qemu >> b/examples/apparmor/libvirt-qemu >> index 73bdbae87..3d9eed9ec 100644 >> --- a/examples/apparmor/libvirt-qemu >> +++ b/examples/apparmor/libvirt-qemu >> @@ -25,6 +25,7 @@ >> /dev/ptmx rw, >> /dev/kqemu rw, >> @{PROC}/*/status r, >> + @{PROC}/@{pid}/cmdline r, > > Note this is an information leak and allows reading potentially > sensitive information, such as passwords given on the command line. Eg: > > $ cat /proc/13335/cmdline | tr '\0' ' ' > sh /tmp/testme --password=sensitive Well, I'd say that passing passwords (or any sensitive information) through command line is doomed by definition. Anybody can read that (doing mere ps is enough). > > Would it be possible to use 'owner' match? Eg: > > owner @{PROC}/@{pid}/cmdline r, Okay, this narrows the attack surface, but I guess that somebody else doing `ps' on the system will be able to obtain the password anyway.