** Description changed:
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
+ * The reason is that the lsblk profile does not allow access
+ to /sys/devices/css0.
[ 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
+ 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
+ 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 /
-
+ 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.)
+ would also work without the profile changes.)
- * As a regression test execute lsblk also on a FCP/SCSP
- system, to verify that nothing has changes
+ * As a regression test, execute lsblk also on a FCP/SCSP
+ system, to verify that nothing has changed
(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.
-
+ * This SRU loosens confinement on the lsblk profile. However, if a user
+ manually modified the installed profiles, then the package upgrade would
+ cause conflicts, and rejection of the incoming changes (either by hand
+ during an interactive upgrade or automatically during an batch unattended
+ upgrade) would result in end users not getting the packaged fix.
+
* Check if apparmor is enabled and the profile active:
sudo aa-status --enabled
- sudo aa-status --show=all | grep unprivileged_userns
-
+ sudo aa-status --show=all | grep lsblk
+
* 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.
__________
Hey,
while debugging bug 2107402 we found that there is more to fix.
Running lsblk in a container on s390x hits this:
[12064869.934674] audit: type=1400 audit(1744791155.353:111962):
apparmor="DENIED" operation="file_mmap" class="file"
namespace="root//lxd-p_<var-snap-lxd-common-lxd>" profile="lsblk"
name="/usr/bin/lsblk" pid=3286747 comm="lsblk" requested_mask="rm"
denied_mask="rm" fsuid=1000000 ouid=1000000
To the user it just segfaults.
root@p:~# lsblk
Segmentation fault
root@p:~# aa-disable lsblk
Disabling /usr/bin/lsblk.
root@p:~# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
loop0 7:0 0 93.8M 1 loop
loop1 7:1 0 94M 1 l
...
--
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to apparmor in Ubuntu.
https://bugs.launchpad.net/bugs/2107455
Title:
segfault of lsblk s390x in containers due to apparmor
Status in Ubuntu on IBM z Systems:
Confirmed
Status in apparmor package in Ubuntu:
Fix Released
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 lsblk profile does not allow access
to /sys/devices/css0.
[ 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 work without the profile changes.)
* As a regression test, execute lsblk also on a FCP/SCSP
system, to verify that nothing has changed
(since this was not affected).
[ Where problems could occur ]
* This SRU loosens confinement on the lsblk profile. However, if a user
manually modified the installed profiles, then the package upgrade would
cause conflicts, and rejection of the incoming changes (either by hand
during an interactive upgrade or automatically during an batch unattended
upgrade) would result in end users not getting the packaged fix.
* Check if apparmor is enabled and the profile active:
sudo aa-status --enabled
sudo aa-status --show=all | grep lsblk
* 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.
__________
Hey,
while debugging bug 2107402 we found that there is more to fix.
Running lsblk in a container on s390x hits this:
[12064869.934674] audit: type=1400 audit(1744791155.353:111962):
apparmor="DENIED" operation="file_mmap" class="file"
namespace="root//lxd-p_<var-snap-lxd-common-lxd>" profile="lsblk"
name="/usr/bin/lsblk" pid=3286747 comm="lsblk" requested_mask="rm"
denied_mask="rm" fsuid=1000000 ouid=1000000
To the user it just segfaults.
root@p:~# lsblk
Segmentation fault
root@p:~# aa-disable lsblk
Disabling /usr/bin/lsblk.
root@p:~# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
loop0 7:0 0 93.8M 1 loop
loop1 7:1 0 94M 1 l
...
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