Bug 2256442 - avc: denied { read write } for pid=12364 comm="plymouthd" name="kmsg" dev="devtmpfs" ino=10 scontext=system_u:system_r:plymouthd_t:s0 tcontext=system_u:object_r:kmsg_device_t:s0 tclass=chr_file permissive=1
Summary: avc: denied { read write } for pid=12364 comm="plymouthd" name="kmsg" dev="de...
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Fedora
Classification: Fedora
Component: selinux-policy
Version: 40
Hardware: Unspecified
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Zdenek Pytela
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2024-01-02 10:17 UTC by Bruno Goncalves
Modified: 2024-04-19 21:36 UTC (History)
8 users (show)

Fixed In Version: selinux-policy-40.16-1.fc40
Clone Of:
Environment:
Last Closed: 2024-04-19 21:36:06 UTC
Type: ---
Embargoed:


Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Github fedora-selinux selinux-policy pull 2035 0 None Draft Allow plymouthd log during shutdown 2024-02-12 16:39:29 UTC

Description Bruno Goncalves 2024-01-02 10:17:13 UTC
The following avc denials are shown when booting the system:

SELinux status:                 enabled
SELinuxfs mount:                /sys/fs/selinux
SELinux root directory:         /etc/selinux
Loaded policy name:             targeted
Current mode:                   permissive
Mode from config file:          permissive
Policy MLS status:              enabled
Policy deny_unknown status:     allowed
Memory protection checking:     actual (secure)
Max kernel policy version:      33
selinux-policy-40.8-1.fc40.noarch
----
time->Mon Jan  1 08:29:26 2024
type=AVC msg=audit(1704115766.362:614): avc:  denied  { read write } for  pid=12364 comm="plymouthd" name="kmsg" dev="devtmpfs" ino=10 scontext=system_u:system_r:plymouthd_t:s0 tcontext=system_u:object_r:kmsg_device_t:s0 tclass=chr_file permissive=1
----
time->Mon Jan  1 08:29:26 2024
type=AVC msg=audit(1704115766.362:615): avc:  denied  { open } for  pid=12364 comm="plymouthd" path="/dev/kmsg" dev="devtmpfs" ino=10 scontext=system_u:system_r:plymouthd_t:s0 tcontext=system_u:object_r:kmsg_device_t:s0 tclass=chr_file permissive=1
----
time->Mon Jan  1 08:29:26 2024
type=AVC msg=audit(1704115766.362:616): avc:  denied  { syslog_read } for  pid=12364 comm="plymouthd" scontext=system_u:system_r:plymouthd_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=system permissive=1


Reproducible: Always

Steps to Reproduce:
1.Boot the machine
2.
3.

Comment 1 Zdenek Pytela 2024-01-02 10:50:32 UTC
Hi Bruno,

This denial does not reproduce out of the box, do you happen to know which changes are needed?

Comment 2 Bruno Goncalves 2024-01-02 12:39:23 UTC
here is the log using full audit:

SELinux status:                 enabled
SELinuxfs mount:                /sys/fs/selinux
SELinux root directory:         /etc/selinux
Loaded policy name:             targeted
Current mode:                   permissive
Mode from config file:          permissive
Policy MLS status:              enabled
Policy deny_unknown status:     allowed
Memory protection checking:     actual (secure)
Max kernel policy version:      33
selinux-policy-40.8-1.fc40.noarch
----
time->Tue Jan  2 13:34:25 2024
type=PROCTITLE msg=audit(1704198865.507:253): proctitle=2F7573722F7362696E2F706C796D6F75746864002D2D6D6F64653D7265626F6F74002D2D6174746163682D746F2D73657373696F6E
type=PATH msg=audit(1704198865.507:253): item=0 name="/dev/kmsg" inode=10 dev=00:05 mode=020644 ouid=0 ogid=0 rdev=01:0b obj=system_u:object_r:kmsg_device_t:s0 nametype=NORMAL cap_fp=0 cap_fi=0 cap_fe=0 cap_fver=0 cap_frootid=0
type=CWD msg=audit(1704198865.507:253): cwd="/"
type=SYSCALL msg=audit(1704198865.507:253): arch=c000003e syscall=257 success=yes exit=9 a0=ffffff9c a1=7fbc53c0350a a2=802 a3=0 items=1 ppid=10111 pid=10112 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=4294967295 comm="plymouthd" exe="/usr/sbin/plymouthd" subj=system_u:system_r:plymouthd_t:s0 key=(null)
type=AVC msg=audit(1704198865.507:253): avc:  denied  { syslog_read } for  pid=10112 comm="plymouthd" scontext=system_u:system_r:plymouthd_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=system permissive=1
type=AVC msg=audit(1704198865.507:253): avc:  denied  { open } for  pid=10112 comm="plymouthd" path="/dev/kmsg" dev="devtmpfs" ino=10 scontext=system_u:system_r:plymouthd_t:s0 tcontext=system_u:object_r:kmsg_device_t:s0 tclass=chr_file permissive=1
type=AVC msg=audit(1704198865.507:253): avc:  denied  { read write } for  pid=10112 comm="plymouthd" name="kmsg" dev="devtmpfs" ino=10 scontext=system_u:system_r:plymouthd_t:s0 tcontext=system_u:object_r:kmsg_device_t:s0 tclass=chr_file permissive=1

Comment 3 Bruno Goncalves 2024-01-02 12:40:09 UTC
(In reply to Zdenek Pytela from comment #1)
> Hi Bruno,
> 
> This denial does not reproduce out of the box, do you happen to know which
> changes are needed?

hmm, indeed. The problem seem to happen when we boot the machine after installing a new kernel.

example: https://datawarehouse.cki-project.org/kcidb/tests/10748869

Comment 5 Zdenek Pytela 2024-01-02 13:59:10 UTC
I cannot reproduce it just by installing a kernel and rebooting, so I wonder is the triggering condition.

Comment 6 Zdenek Pytela 2024-01-02 16:02:37 UTC
Happens during shutdown:

type=PROCTITLE msg=audit(01/02/2024 10:27:30.470:537) : proctitle=/usr/sbin/plymouthd --mode=reboot --attach-to-session 
type=PATH msg=audit(01/02/2024 10:27:30.470:537) : item=0 name=/dev/kmsg inode=10 dev=00:05 mode=character,644 ouid=root ogid=root rdev=01:0b obj=system_u:object_r:kmsg_device_t:s0 nametype=NORMAL cap_fp=none cap_fi=none cap_fe=0 cap_fver=0 cap_frootid=0 
type=CWD msg=audit(01/02/2024 10:27:30.470:537) : cwd=/ 
type=SYSCALL msg=audit(01/02/2024 10:27:30.470:537) : arch=x86_64 syscall=openat success=yes exit=9 a0=AT_FDCWD a1=0x7f20c822f50a a2=O_RDWR|O_NONBLOCK a3=0x0 items=1 ppid=22623 pid=22627 auid=unset uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=(none) ses=unset comm=plymouthd exe=/usr/sbin/plymouthd subj=system_u:system_r:plymouthd_t:s0 key=(null) 
type=AVC msg=audit(01/02/2024 10:27:30.470:537) : avc:  denied  { syslog_read } for  pid=22627 comm=plymouthd scontext=system_u:system_r:plymouthd_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=system permissive=1 
type=AVC msg=audit(01/02/2024 10:27:30.470:537) : avc:  denied  { open } for  pid=22627 comm=plymouthd path=/dev/kmsg dev="devtmpfs" ino=10 scontext=system_u:system_r:plymouthd_t:s0 tcontext=system_u:object_r:kmsg_device_t:s0 tclass=chr_file permissive=1 
type=AVC msg=audit(01/02/2024 10:27:30.470:537) : avc:  denied  { read write } for  pid=22627 comm=plymouthd name=kmsg dev="devtmpfs" ino=10 scontext=system_u:system_r:plymouthd_t:s0 tcontext=system_u:object_r:kmsg_device_t:s0 tclass=chr_file permissive=1 

in enforcing:

type=PROCTITLE msg=audit(01/02/2024 10:31:36.423:223) : proctitle=/usr/sbin/plymouthd --mode=shutdown --attach-to-session 
type=PATH msg=audit(01/02/2024 10:31:36.423:223) : item=0 name=/dev/kmsg inode=10 dev=00:05 mode=character,644 ouid=root ogid=root rdev=01:0b obj=system_u:object_r:kmsg_device_t:s0 nametype=NORMAL cap_fp=none cap_fi=none cap_fe=0 cap_fver=0 cap_frootid=0 
type=CWD msg=audit(01/02/2024 10:31:36.423:223) : cwd=/ 
type=SYSCALL msg=audit(01/02/2024 10:31:36.423:223) : arch=x86_64 syscall=openat success=no exit=EACCES(Permission denied) a0=AT_FDCWD a1=0x7f0ce7f9650a a2=O_RDWR|O_NONBLOCK a3=0x0 items=1 ppid=968 pid=974 auid=unset uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=(none) ses=unset comm=plymouthd exe=/usr/sbin/plymouthd subj=system_u:system_r:plymouthd_t:s0 key=(null) 
type=AVC msg=audit(01/02/2024 10:31:36.423:223) : avc:  denied  { read write } for  pid=974 comm=plymouthd name=kmsg dev="devtmpfs" ino=10 scontext=system_u:system_r:plymouthd_t:s0 tcontext=system_u:object_r:kmsg_device_t:s0 tclass=chr_file permissive=0 

# /usr/lib/systemd/system/plymouth-reboot.service
[Unit]
Description=Show Plymouth Reboot Screen
After=getty display-manager.service plymouth-start.service
Before=systemd-reboot.service
DefaultDependencies=no
ConditionKernelCommandLine=!plymouth.enable=0
ConditionVirtualization=!container

[Service]
ExecStart=/usr/sbin/plymouthd --mode=reboot --attach-to-session
ExecStartPost=-/usr/bin/plymouth show-splash
Type=forking
RemainAfterExit=yes

Comment 7 Milos Malik 2024-01-03 11:09:40 UTC
Test coverage for this bug exists in a form of PR:
 * https://src.fedoraproject.org/tests/selinux/pull-request/461

The PR waits for a review.

Comment 8 Aoife Moloney 2024-02-15 23:08:34 UTC
This bug appears to have been reported against 'rawhide' during the Fedora Linux 40 development cycle.
Changing version to 40.

Comment 9 Fedora Update System 2024-03-15 23:44:35 UTC
FEDORA-2024-883c7e0684 (selinux-policy-40.15-1.fc40) has been submitted as an update to Fedora 40.
https://bodhi.fedoraproject.org/updates/FEDORA-2024-883c7e0684

Comment 10 Fedora Update System 2024-03-16 01:06:42 UTC
FEDORA-2024-883c7e0684 has been pushed to the Fedora 40 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2024-883c7e0684`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2024-883c7e0684

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 11 Fedora Update System 2024-04-15 02:19:19 UTC
FEDORA-2024-d0565faae7 has been pushed to the Fedora 40 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2024-d0565faae7`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2024-d0565faae7

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 12 Fedora Update System 2024-04-19 21:36:06 UTC
FEDORA-2024-d0565faae7 (selinux-policy-40.16-1.fc40) has been pushed to the Fedora 40 stable repository.
If problem still persists, please make note of it in this bug report.


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