selinux November 2022

selinux@lists.fedoraproject.org

7 participants
7 discussions

Setting context in early boot
by Frederick Grose 11 Dec '25

11 Dec '25

I have a general scoping question on setting SELinux context on files/directories during early boot. I'm working on a feature in dracut to implement general stacking of filesystem hierarchies via OverlayFS for the root filesystem within the dmsquash-live-root module. How should I address the setting of context for new files, directories, or links needed to assemble the components for the OverlayFS mount? For example, when I mkdir -m 0755 -p --context=system_u:object_r:root_t:s0 /run/somemountpoint I get this warning in the journal: mkdir: warning: ignoring --context; it requires an SELinux/SMACK-enabled kernel If the SELinux code is not active at this early stage, what is to be done?

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SELinux is preventing systemd-tmpfile from using the sys_resource capability.
by Manfred Lotz 31 Jul '25

31 Jul '25

Hi there, Running Fedora 31 and SELinux still in permissive mode I got SELinux is preventing systemd-tmpfile from using the sys_resource capability. ***** Plugin sys_resource (91.4 confidence) suggests ********************** If you do not want processes to require capabilities to use up all the system resources on your syste> Then you need to diagnose why your system is running out of system resources and fix the problem. According to /usr/include/linux/capability.h, sys_resource is required to: /* Override resource limits. Set resource limits. */ /* Override quota limits. */ /* Override reserved space on ext2 filesystem */ /* Modify data journaling mode on ext3 filesystem (uses journaling resources) */ /* NOTE: ext2 honors fsuid when checking for resource overrides, so you can override using fsuid too */ /* Override size restrictions on IPC message queues */ /* Allow more than 64hz interrupts from the real-time clock */ /* Override max number of consoles on console allocation */ /* Override max number of keymaps */ Do fix the cause of the SYS_RESOURCE on your system. ***** Plugin catchall (9.59 confidence) suggests ************************** If you believe that systemd-tmpfile should have the sys_resource capability by default. Then you should report this as a bug. You can generate a local policy module to allow this access. Do allow this access for now by executing: # ausearch -c 'systemd-tmpfile' --raw | audit2allow -M my-systemdtmpfile # semodule -X 300 -i my-systemdtmpfile.pp I also see type=AVC msg=audit(1569414241.452:321): avc: denied { sys_resource } for pid=17409 comm="systemd-tmpfile" capability=24 scontext=system_u:system_r:systemd_tmpfiles_t:s0 tcontext=system_u:system_r:systemd_tmpfiles_t:s0 tclass=capability permissive=1 type=AVC msg=audit(1569414241.452:322): avc: denied { setrlimit } for pid=17409 comm="systemd-tmpfile" scontext=system_u:system_r:systemd_tmpfiles_t:s0 tcontext=system_u:system_r:systemd_tmpfiles_t:s0 tclass=process permissive=1 I have to admit I don't know how to judge this. Before I do anything here I like to understand. -- Manfred

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Not possible to specify smtp password for setroubleshootd?
by Matt Kinni 09 Jun '24

09 Jun '24

Hello, I run a Fedora 35 server and would like setroubleshootd to send email alerts for avc denials, but I'm having trouble configuring this due to the apparent lack of support for configuring an smtp password. The out of the box setroubleshoot.conf sets > smtp_host = localhost > smtp_port = 25 > from_address = SELinux_Troubleshoot , but there is no config parameter for smtp password. For this to actually work on a machine acting as an MTA (I have postfix running locally), the mail server would have to be configured to allow unauthenticated port 25 connections to masquerade as any local system user, which no decent postfix setup would allow. I am not a python programmer, but in my reading of https://pagure.io/setroubleshoot/blob/main/f/framework/src/setroubleshoot/e…, it doesn't appear there is any built in way to support authenticated email sending despite the underlying smtplib being able to do it. I would suggest either a) adding password support for smtplib, or/and b) adding an option to send mail using the sendmail binary, which allows postfix to recognize the running user without any password needed. Has anyone else run into problems deploying the setroubleshootd email alerts in practice? email_alert.py appears simple enough to hack in password support, but I feel a security oriented project like selinux shouldn't require an insecure mail setup in order to send its alerts. Any tips are welcome, Thanks, Matt

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certmonger post-save scripts & certmonger_unconfined_t domain
by Sam Morris 06 Jun '24

06 Jun '24

Certmonger allows for the configuration of a post-save command to be run after it has obtained new certificates. This can be used to copy the key & certificates out of wherever certmonger is allowed to put them, and save them elsewhere with a particular owner/group, combine the certificate & chain into a single file as required by some software, etc. The problem comes with SELinux which prevents my post-save scripts from being able to do all of that. I thought the solution was to give the scripts the context of certmonger_unconfined_exec_t, which would cause a transition to the certmonger_unconfined_t domain which is as its name suggests unconfined; but I can't get this to work. I'm trying to use runcon to simulate certmonger executing a fake script: # cat /tmp/fakescript #!/bin/bash set -eu id -Z # /tmp/fakescript unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 # ls -Z /tmp/fakescript unconfined_u:object_r:certmonger_unconfined_exec_t:s0 /tmp/fakescript # runcon system_u:system_r:certmonger_t:s0 /tmp/fakescript runcon: ‘/tmp/fakescript’: Permission denied Here is the avc denial: ---- type=PROCTITLE msg=audit(27/04/21 16:16:47.156:153492) : proctitle=runcon system_u:system_r:certmonger_t:s0 /tmp/fakescript type=SYSCALL msg=audit(27/04/21 16:16:47.156:153492) : arch=x86_64 syscall=execve success=no exit=EACCES(Permission denied) a0=0x7ffd8aa768ab a1=0x7ffd8aa75888 a2=0x7ffd8aa75898 a3=0x0 items=0 ppid=177795 pid=177796 auid=sam.admin uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=pts5 ses=103 comm=runcon exe=/usr/bin/runcon subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null) type=AVC msg=audit(27/04/21 16:16:47.156:153492) : avc: denied { entrypoint } for pid=177796 comm=runcon path=/tmp/fakescript dev="dm-0" ino=33563064 scontext=system_u:system_r:certmonger_t:s0 tcontext=unconfined_u:object_r:certmonger_unconfined_exec_t:s0 tclass=file permissive=0 Even though: # sepolicy transition -s certmonger_t -t certmonger_unconfined_t certmonger_t @ certmonger_unconfined_exec_t --> certmonger_unconfined_t Diving in a little deeper, I can see that certmonger can execute the file: # sesearch -s certmonger_t -t certmonger_unconfined_exec_t -c file -p execute -A allow certmonger_t certmonger_unconfined_exec_t:file { execute execute_no_trans getattr ioctl map open read }; ... and that the file type is an entrypoint for the certmonger_unconfined_t domain: # sesearch -s certmonger_unconfined_t -t certmonger_unconfined_exec_t -c file -p entrypoint -A allow certmonger_unconfined_t certmonger_unconfined_exec_t:file { entrypoint execute getattr ioctl lock map open read }; ... and that transition is permitted from certmonger_t: # sesearch -s certmonger_t -t certmonger_unconfined_t -c process -p transition -A allow certmonger_t certmonger_unconfined_t:process transition; Which leaves me scratching my head, unsure why it doesn't work in practice... -- Sam Morris <https://robots.org.uk/> PGP: rsa4096/CAAA AA1A CA69 A83A 892B 1855 D20B 4202 5CDA 27B9

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Correct way to handle SELinux for a systemd-started SSH VPN
by Chris Adams 20 Nov '22

20 Nov '22

I am starting an SSH VPN connection with a systemd service. It's just a simple service, with an ExecStart to run ssh. If I wrap it with a shell (ExecStart=/bin/sh -c "/usr/bin/ssh %i"), it runs; if I take out the shell wrap (ExecStart=/usr/bin/ssh %i), it fails due to SELinux not allowing it. If I set permissive mode, there's a whole lot of different things that init_t is not allowed to do. :) So obviously I can just run with the shell wrapper, but is there a more proper way to do this? -- Chris Adams <linux(a)cmadams.net>

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Docker Container files MCS labelling not being implemented in Fedora 32
by Aswad Tariq 15 Nov '22

15 Nov '22

In Docker version 20.10.7, build f0df350 and with SE-Linux enabled and set to enforcing mode with policy as targeted the MCS labels should be applied to containers and their files by default. I should see user:role:type:s0:c1,c34 for example but instead the category labels are not applied and I see user:role:type:s0 for files inside the container when running ls -lZ or in audit records. The version of Fedora is 32 with kernel version 5.6.6-300.fc32.x86_64. This would be simpler if the labels were not being applied to podman containers but when making files in podman containers the category labels are being set and working fine. Any idea as to what could be the issue. Thanks!

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Allow file access to two different domains
by Gionatan Danti 01 Nov '22

01 Nov '22

Hi all, as one file/dir can have one and only one selinux label, I wonder if/how one can allow processes from different domains to access the same files/dirs. I know that for specific executable and directory one can use the appropriate bools, for example samba_enable_home_dirs enables smbd to read/write home_root_t types. I also know that one can create and load a custom policy to allow the required access. However, I wonder if an easier approach exists to let processes with different domains to access the same set of files or directories. Any clue? Thanks. -- Danti Gionatan Supporto Tecnico Assyoma S.r.l. - www.assyoma.it email: g.danti(a)assyoma.it - info(a)assyoma.it GPG public key ID: FF5F32A8

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selinux November 2022