Bug 1729756

(In reply to Lukas Hejtmanek from comment #0)
Hey Lukas,

I didn't see this AVC during my krb5/NFS testings.

> this is the file:
> ls -Z /tmp/krb5cc_0
> -rw-------. root root system_u:object_r:gssd_tmp_t:s0  /tmp/krb5cc_0

It's different from my side:

[root]# ls -Z /tmp/krb5cc_0
-rw-------. root root unconfined_u:object_r:user_tmp_t:s0 /tmp/krb5cc_0
[root]# getenforce
Enforcing

> 
> Version-Release number of selected component (if applicable):
> everything from 7.6 RHEL up to date.

By the way, have you tried any version before 7.6? Does it work as expected?

Did you try to mount any kerberize NFS volume while there is that -rw-------. root root unconfined_u:object_r:user_tmp_t:s0 /tmp/krb5cc_0 file?

I did not test any previous version.

Okay, after mounting as krb5, the "security context" is updated to "system_u:object_r:gssd_tmp_t:s0".

But I still didn't encounter the failure of comment #0:
-----------------------------------------------------
[root ~]# mount -t nfs4 -o sec=krb5 $HOSTNAME:/ /mnt/
[root ~]# nfsstat -m
/mnt from rhel-7.7.redhat.com:/
 Flags: rw,relatime,vers=4.1,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=krb5,clientaddr=10.10.10.10,local_lock=none,addr=10.10.10.10

[root ~]# ls -Z /tmp/krb5cc_0
-rw-------. root root system_u:object_r:gssd_tmp_t:s0  /tmp/krb5cc_0
                      ^^^^^^^^^
[root ~]# grep gssd /var/log/messages | egrep -i "err|warn"
[root ~]# grep denied /var/log/audit/audit.log 
[root ~]#

[root@ursa ~]# sestatus 
SELinux status:                 enabled
SELinuxfs mount:                /sys/fs/selinux
SELinux root directory:         /etc/selinux
Loaded policy name:             targeted
Current mode:                   enforcing
Mode from config file:          enforcing
Policy MLS status:              enabled
Policy deny_unknown status:     allowed
Max kernel policy version:      31
[root@ursa ~]#

[root@ursa ~]# mount -t nfs4 -o sec=krb5 storage-brno1-cerit.metacentrum.cz:/ /mnt/storage-brno1-cerit
mount.nfs4: access denied by server while mounting storage-brno1-cerit.metacentrum.cz:/
[root@ursa ~]# ls -Z /tmp/krb5cc_0
-rw-------. root root system_u:object_r:tmp_t:s0       /tmp/krb5cc_0
[root@ursa ~]# 

[root@ursa ~]# date
Tue Jul 23 01:35:50 CEST 2019
[root@ursa ~]# grep gssd /var/log/messages | egrep -i "err|warn"
[root@ursa ~]# grep denied /var/log/audit/audit.log
type=AVC msg=audit(1563838547.187:235): avc:  denied  { unlink } for  pid=45595 comm="rpc.gssd" name="krb5cc_0" dev="md126p4" ino=67160166 scontext=system_u:system_r:gssd_t:s0 tcontext=system_u:object_r:tmp_t:s0 tclass=file permissive=0
type=AVC msg=audit(1563838547.189:236): avc:  denied  { unlink } for  pid=45595 comm="rpc.gssd" name="krb5cc_0" dev="md126p4" ino=67160166 scontext=system_u:system_r:gssd_t:s0 tcontext=system_u:object_r:tmp_t:s0 tclass=file permissive=0
type=AVC msg=audit(1563838547.191:237): avc:  denied  { unlink } for  pid=45595 comm="rpc.gssd" name="krb5cc_0" dev="md126p4" ino=67160166 scontext=system_u:system_r:gssd_t:s0 tcontext=system_u:object_r:tmp_t:s0 tclass=file permissive=0
type=AVC msg=audit(1563838547.193:238): avc:  denied  { unlink } for  pid=45595 comm="rpc.gssd" name="krb5cc_0" dev="md126p4" ino=67160166 scontext=system_u:system_r:gssd_t:s0 tcontext=system_u:object_r:tmp_t:s0 tclass=file permissive=0
type=AVC msg=audit(1563838547.196:239): avc:  denied  { unlink } for  pid=45595 comm="rpc.gssd" name="krb5cc_0" dev="md126p4" ino=67160166 scontext=system_u:system_r:gssd_t:s0 tcontext=system_u:object_r:tmp_t:s0 tclass=file permissive=0
type=AVC msg=audit(1563838547.198:240): avc:  denied  { unlink } for  pid=45595 comm="rpc.gssd" name="krb5cc_0" dev="md126p4" ino=67160166 scontext=system_u:system_r:gssd_t:s0 tcontext=system_u:object_r:tmp_t:s0 tclass=file permissive=0
type=AVC msg=audit(1563838547.252:241): avc:  denied  { unlink } for  pid=45595 comm="rpc.gssd" name="krb5cc_0" dev="md126p4" ino=67160166 scontext=system_u:system_r:gssd_t:s0 tcontext=system_u:object_r:tmp_t:s0 tclass=file permissive=0
type=AVC msg=audit(1563838547.254:242): avc:  denied  { unlink } for  pid=45595 comm="rpc.gssd" name="krb5cc_0" dev="md126p4" ino=67160166 scontext=system_u:system_r:gssd_t:s0 tcontext=system_u:object_r:tmp_t:s0 tclass=file permissive=0
type=AVC msg=audit(1563838547.256:243): avc:  denied  { unlink } for  pid=45595 comm="rpc.gssd" name="krb5cc_0" dev="md126p4" ino=67160166 scontext=system_u:system_r:gssd_t:s0 tcontext=system_u:object_r:tmp_t:s0 tclass=file permissive=0
type=AVC msg=audit(1563838547.257:244): avc:  denied  { unlink } for  pid=45595 comm="rpc.gssd" name="krb5cc_0" dev="md126p4" ino=67160166 scontext=system_u:system_r:gssd_t:s0 tcontext=system_u:object_r:tmp_t:s0 tclass=file permissive=0
type=AVC msg=audit(1563838547.270:245): avc:  denied  { unlink } for  pid=45595 comm="rpc.gssd" name="krb5cc_0" dev="md126p4" ino=67160166 scontext=system_u:system_r:gssd_t:s0 tcontext=system_u:object_r:tmp_t:s0 tclass=file permissive=0
type=AVC msg=audit(1563838547.272:246): avc:  denied  { unlink } for  pid=45595 comm="rpc.gssd" name="krb5cc_0" dev="md126p4" ino=67160166 scontext=system_u:system_r:gssd_t:s0 tcontext=system_u:object_r:tmp_t:s0 tclass=file permissive=0



[root@ursa ~]# rm /tmp/krb5cc_0
rm: remove regular file ‘/tmp/krb5cc_0’? y
[root@ursa ~]# mount -t nfs4 -o sec=krb5 storage-brno1-cerit.metacentrum.cz:/ /mnt/storage-brno1-cerit
[root@ursa ~]# 

[root@ursa ~]# ls -Z /tmp/krb5cc_0
-rw-------. root root system_u:object_r:gssd_tmp_t:s0  /tmp/krb5cc_0
[root@ursa ~]#

I'm running RHEL 7.8 and on all machines I get:

[tanderson@test-sl01 ~]$ ls -Z /tmp/krb5cc_0
-rw-------. root root system_u:object_r:gssd_tmp_t:s0  /tmp/krb5cc_0

But I'm only getting there avc: denied on 2 out of 6 machines and those 2 are luckilly test machines.  Everything is managed by puppet and they are machines that were built as 7.8.

After evaluating this issue, there are no plans to address it further or fix it in an upcoming release.  Therefore, it is being closed.  If plans change such that this issue will be fixed in an upcoming release, then the bug can be reopened.