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https://bugs.launchpad.net/bugs/2107402
Title:
lsblk on IBM z Systems blocked by apparmor in 25.04
Status in Release Notes for Ubuntu:
Fix Released
Status in Ubuntu on IBM z Systems:
In Progress
Status in apparmor package in Ubuntu:
Fix Released
Status in util-linux package in Ubuntu:
Invalid
Status in apparmor source package in Plucky:
In Progress
Status in util-linux source package in Plucky:
Invalid
Status in apparmor source package in Questing:
Fix Released
Status in util-linux source package in Questing:
Invalid
Bug description:
SRU Justification:
[ Impact ]
* lsblk on an s390x system that uses DASD disks shows no output.
* journactl shows lsblk is blocked by apparmor:
2025-04-15T15:02:26.048075+00:00 s5lp1-gen03 kernel: audit: type=1400
audit(1744729346.034:270): apparmor="DENIED" operation="open"
class="file" profile="lsblk" name="/sys/devices/css0/
0.0.0000/0.0.0101/block/dasda/hidden" pid=2070 comm="lsblk"
requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
* The reason is that the unprivileged_userns profile does not
have access to /.
* In case of running lsblk in a container the lsblk command
will even segfault, instead of returning just nothing.
[ Fix ]
* unprivileged_userns profile: Allow full file system access
https://gitlab.com/apparmor/apparmor/-/commit/8138bc60d18a7939af766c322586c4268e2940e3
[ Test Plan ]
* Install Ubuntu Server 25.04 on IBM Z in LPAR, z/VM or KVM
using DASD ECKD disks.
* Please notice that testing this at install time using the installer
shell is not sufficient, since the profile is not active at that time.
* Ensure util-linux and the s390-tools are installed
(which is by default).
* Do an lsdasd, it should list DASD ECKD disks, similar to:
$ lsdasd
Bus-ID Status Name Device Type BlkSz Size Blocks
================================================================================
0.0.0200 active dasda 94:0 ECKD 4096 7042MB 1802880
0.0.0300 active dasdb 94:4 ECKD 4096 7042MB 1802880
0.0.0400 active dasdc 94:8 ECKD 4096 21128MB 5409000
* Now execute lsblk (and watch the journal)
- on a system that is not patched,
one will see no output in the Terminal
(or in case of running in a container a segfault),
and messages like this in the journal:
2025-04-15T15:02:26.048075+00:00 hwe0006 kernel: audit: type=1400
audit(1744729346.034:270): apparmor="DENIED" operation="open"
class="file" profile="lsblk" name="/sys/devices/css0/
0.0.0000/0.0.0200/block/dasda/hidden" pid=2070 comm="lsblk"
requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
...
- on a patched system, lsblk should provide a proper output
similar to this:
$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
loop0 7:0 0 65.4M 1 loop
loop1 7:1 0 65.4M 1 loop /snap/core22/1909
loop2 7:2 0 39.9M 1 loop
loop3 7:3 0 98.7M 1 loop /snap/lxd/32454
loop4 7:4 0 39.9M 1 loop /snap/snapd/23776
loop5 7:5 0 65.4M 1 loop
loop6 7:6 0 100M 1 loop /snap/lxd/33109
loop7 7:7 0 46.2M 1 loop /snap/snapd/24506
loop8 7:8 0 65.4M 1 loop /snap/core22/1965
dasda 94:0 0 20.6G 0 disk
└─dasda1 94:1 0 20.6G 0 part
└─hwe0006--vg-hwe0006--lv 253:0 0 47.1G 0 lvm /
dasdb 94:4 0 6.9G 0 disk
├─dasdb1 94:5 0 1G 0 part /boot
└─dasdb2 94:6 0 5.9G 0 part
└─hwe0006--vg-hwe0006--lv 253:0 0 47.1G 0 lvm /
dasdc 94:8 0 20.6G 0 disk
└─dasdc1 94:9 0 20.6G 0 part
└─hwe0006--vg-hwe0006--lv 253:0 0 47.1G 0 lvm /
* (After having done 'aa-disable lsblk' lsblk would also work
would also ork without the profile changes.)
* As a regression test execute lsblk also on a FCP/SCSP
system, to verify that nothing has changes
(since this was not affected).
[ Where problems could occur ]
* The changes in profiles/apparmor.d/unprivileged_userns
are relatively small, just:
- allow file rwlkm /**,
+ allow file rwlkm /{,**},
but expand the prvilidges a bit.
* Check if apparmor is enabled and the profile active:
sudo aa-status --enabled
sudo aa-status --show=all | grep unprivileged_userns
* This should not have an impact on other (disk type) devices
like SCSI/FCP, but better check (see test plan, last bullet).
[ Other Info ]
* The modification is already included in questing.
* The patch was tested also successfully tested in plucky on s390x.
* Since the issue and the tests are very similar in LP#2107455
and LP#2107402. Hence this SRU justification was added
to both of these two LP bugs.
__________
Fresh install of 25.04 on s390x. Same happens also on upgrade from
24.10 to 25.04
lsblk returns no output
journactl shows it is blocked by apparmor
This works fine for SCSI devices, it fails only for DASD.
```
2025-04-15T15:02:26.048055+00:00 s5lp1-gen03 kernel: kauditd_printk_skb: 6
callbacks suppressed
2025-04-15T15:02:26.048075+00:00 s5lp1-gen03 kernel: audit: type=1400
audit(1744729346.034:270): apparmor="DENIED" operation="open" class="file"
profile="lsblk" name="/sys/devices/css0/0.0.0000/0.0.0101/block/dasda/hidden"
pid=2070 comm="lsblk" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
2025-04-15T15:02:26.048077+00:00 s5lp1-gen03 kernel: audit: type=1400
audit(1744729346.034:271): apparmor="DENIED" operation="open" class="file"
profile="lsblk" name="/sys/devices/css0/0.0.0000/0.0.0101/block/dasda/dev"
pid=2070 comm="lsblk" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
2025-04-15T15:02:26.048078+00:00 s5lp1-gen03 kernel: audit: type=1400
audit(1744729346.034:272): apparmor="DENIED" operation="open" class="file"
profile="lsblk" name="/sys/devices/css0/0.0.0003/0.0.0104/block/dasdd/hidden"
pid=2070 comm="lsblk" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
2025-04-15T15:02:26.048079+00:00 s5lp1-gen03 kernel: audit: type=1400
audit(1744729346.034:273): apparmor="DENIED" operation="open" class="file"
profile="lsblk" name="/sys/devices/css0/0.0.0003/0.0.0104/block/dasdd/dev"
pid=2070 comm="lsblk" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
2025-04-15T15:02:26.048080+00:00 s5lp1-gen03 kernel: audit: type=1400
audit(1744729346.034:274): apparmor="DENIED" operation="open" class="file"
profile="lsblk" name="/sys/devices/css0/0.0.0001/0.0.0102/block/dasdb/hidden"
pid=2070 comm="lsblk" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
2025-04-15T15:02:26.048080+00:00 s5lp1-gen03 kernel: audit: type=1400
audit(1744729346.034:275): apparmor="DENIED" operation="open" class="file"
profile="lsblk" name="/sys/devices/css0/0.0.0001/0.0.0102/block/dasdb/dev"
pid=2070 comm="lsblk" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
2025-04-15T15:02:26.048081+00:00 s5lp1-gen03 kernel: audit: type=1400
audit(1744729346.034:276): apparmor="DENIED" operation="open" class="file"
profile="lsblk" name="/sys/devices/css0/0.0.0002/0.0.0103/block/dasdc/hidden"
pid=2070 comm="lsblk" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
2025-04-15T15:02:26.048081+00:00 s5lp1-gen03 kernel: audit: type=1400
audit(1744729346.034:277): apparmor="DENIED" operation="open" class="file"
profile="lsblk" name="/sys/devices/css0/0.0.0002/0.0.0103/block/dasdc/dev"
pid=2070 comm="lsblk" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
```
Attaching also strace
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