Funny AVC from USB CD plugin

Sun Jan 6 18:50:00 UTC 2008

Running latest Rawhide, targeted/enforcing.

Plugging in an 'old USB CD drive', I got the following audit message:

[root at localhost ~]# sealert -l fb77e7e0-3515-4866-9a8f-e1db99f9b4b8

Summary:

SELinux is preventing ln(/bin/ln) (udev_t) "create" to <Unknown> (etc_t).

Detailed Description:

SELinux denied access requested by ln(/bin/ln). It is not expected that this
access is required by ln(/bin/ln) and this access may signal an intrusion
attempt. It is also possible that the specific version or configuration of the
application is causing it to require additional access.

Allowing Access:

Sometimes labeling problems can cause SELinux denials. You could try to restore
the default system file context for <Unknown>, restorecon -v <Unknown> If this
does not work, there is currently no automatic way to allow this access.
Instead, you can generate a local policy module to allow this access - see FAQ
(http://fedora.redhat.com/docs/selinux-faq-fc5/#id2961385) Or you can disable
SELinux protection altogether. Disabling SELinux protection is not recommended.
Please file a bug report (http://bugzilla.redhat.com/bugzilla/enter_bug.cgi)
against this package.

Additional Information:

Source Context                system_u:system_r:udev_t:SystemLow-SystemHigh
Target Context                system_u:object_r:etc_t
Target Objects                None [ lnk_file ]
Source                        ln(/bin/ln)
Port                          <Unknown>
Host                          localhost.localdomain
Source RPM Packages
Target RPM Packages
Policy RPM                    selinux-policy-3.2.5-8.fc9
Selinux Enabled               True
Policy Type                   targeted
MLS Enabled                   True
Enforcing Mode                Enforcing
Plugin Name                   catchall_file
Host Name                     localhost.localdomain
Platform                      Linux localhost.localdomain
                              2.6.24-0.136.rc6.git12.fc9 #1 SMP Sat Jan 5
                              12:46:45 EST 2008 i686 i686
Alert Count                   2
First Seen                    Sun Jan  6 10:30:15 2008
Last Seen                     Sun Jan  6 10:30:15 2008
Local ID                      fb77e7e0-3515-4866-9a8f-e1db99f9b4b8
Line Numbers

Raw Audit Messages

host=localhost.localdomain type=AVC msg=audit(1199644215.878:31): avc:
 denied  { create } for  pid=6933 comm="ln" name=".is-writeable"
scontext=system_u:system_r:udev_t:s0-s0:c0.c1023
tcontext=system_u:object_r:etc_t:s0 tclass=lnk_file

host=localhost.localdomain type=SYSCALL msg=audit(1199644215.878:31):
arch=40000003 syscall=83 success=no exit=-13 a0=bff3ddc3 a1=bff3ddcd
a2=804f77c a3=0 items=0 ppid=6931 pid=6933 auid=4294967295 uid=0 gid=0
euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) comm="ln"
exe="/bin/ln" subj=system_u:system_r:udev_t:s0-s0:c0.c1023 key=(null)

Here are the messages from /var/log/messages:

Jan  6 10:30:05 localhost kernel: usb 2-2: new full speed USB device
using uhci_hcd and address 4
Jan  6 10:30:06 localhost kernel: usb 2-2: configuration #1 chosen from 1 choice
Jan  6 10:30:06 localhost kernel: scsi8 : SCSI emulation for USB Mass
Storage devices
Jan  6 10:30:06 localhost kernel: usb-storage: device found at 4
Jan  6 10:30:06 localhost kernel: usb-storage: waiting for device to
settle before scanning
Jan  6 10:30:11 localhost kernel: usb-storage: device scan complete
Jan  6 10:30:11 localhost kernel: scsi 8:0:0:0: CD-ROM            IBM
    USB CD-ROM       20A4 PQ: 0 ANSI: 0 CCS
Jan  6 10:30:11 localhost kernel: sr1: scsi3-mmc drive: 10x/10x cd/rw
xa/form2 cdda pop-up
Jan  6 10:30:11 localhost kernel: sr 8:0:0:0: Attached scsi CD-ROM sr1
Jan  6 10:30:11 localhost kernel: sr 8:0:0:0: Attached scsi generic sg2 type 5
Jan  6 10:30:18 localhost setroubleshoot: #012    SELinux is
preventing ln(/bin/ln) (udev_t) "create" to <Unknown>
(etc_t).#012     For complete SELinux messages. run sealert -l
fb77e7e0-3515-4866-9a8f-e1db99f9b4b8

Putting system in permissive mode, I get these:

type=AVC msg=audit(1199645179.126:34): avc:  denied  { create } for
pid=7782 comm="ln" name=".is-writeable"
scontext=system_u:system_r:udev_t:s0-s0:c0.c1023
tcontext=system_u:object_r:etc_t:s0 tclass=lnk_file
type=SYSCALL msg=audit(1199645179.126:34): arch=40000003 syscall=83
success=yes exit=0 a0=bfb56db6 a1=bfb56dc0 a2=804f77c a3=0 items=0
ppid=7780 pid=7782 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0
egid=0 sgid=0 fsgid=0 tty=(none) comm="ln" exe="/bin/ln"
subj=system_u:system_r:udev_t:s0-s0:c0.c1023 key=(null)
type=AVC msg=audit(1199645179.245:35): avc:  denied  { unlink } for
pid=7783 comm="rm" name=".is-writeable" dev=dm-0 ino=11076747
scontext=system_u:system_r:udev_t:s0-s0:c0.c1023
tcontext=system_u:object_r:etc_t:s0 tclass=lnk_file
type=SYSCALL msg=audit(1199645179.245:35): arch=40000003 syscall=301
success=yes exit=0 a0=ffffff9c a1=bfa17dc0 a2=0 a3=bfa17dc0 items=0
ppid=7780 pid=7783 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0
egid=0 sgid=0 fsgid=0 tty=(none) comm="rm" exe="/bin/rm"
subj=system_u:system_r:udev_t:s0-s0:c0.c1023 key=(null)
type=AVC msg=audit(1199645179.255:36): avc:  denied  { append } for
pid=7780 comm="write_cd_rules" name="70-persistent-cd.rules" dev=dm-0
ino=11076866 scontext=system_u:system_r:udev_t:s0-s0:c0.c1023
tcontext=system_u:object_r:etc_t:s0 tclass=file
type=SYSCALL msg=audit(1199645179.255:36): arch=40000003 syscall=5
success=yes exit=3 a0=8a98400 a1=8441 a2=1b6 a3=8441 items=0 ppid=7761
pid=7780 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0
sgid=0 fsgid=0 tty=(none) comm="write_cd_rules" exe="/bin/bash"
subj=system_u:system_r:udev_t:s0-s0:c0.c1023 key=(null)

udev issue?

tom
-- 
Tom London