Bug 1966945
| Summary: | AVC "signull" seen for confined users when executing "sudo" command | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 8 | Reporter: | Renaud Métrich <rmetrich> |
| Component: | selinux-policy | Assignee: | Zdenek Pytela <zpytela> |
| Status: | CLOSED ERRATA | QA Contact: | Milos Malik <mmalik> |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | 8.4 | CC: | daniel.j.arevalo.ctr, lvrabec, mmalik, plautrba, ssekidde |
| Target Milestone: | rc | Keywords: | Triaged |
| Target Release: | 8.6 | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | selinux-policy-3.14.3-84.el8 | Doc Type: | Bug Fix |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2022-05-10 15:14:58 UTC | Type: | Bug |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
| Bug Depends On: | |||
| Bug Blocks: | 1778780 | ||
I've submitted a draft Fedora PR to address the issue: https://github.com/fedora-selinux/selinux-policy/pull/947 Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory (selinux-policy bug fix and enhancement update), and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHBA-2022:1995 |
Description of problem: When "maxlogins" is specified in /etc/security/limits.conf and a confined user (sysadm_u or staff_u) issues a "sudo" command, the following AVC is seen: -------- 8< ---------------- 8< ---------------- 8< ---------------- 8< -------- time->Wed Jun 2 10:05:31 2021 type=PROCTITLE msg=audit(1622621131.587:692): proctitle=7375646F002D75007374616666006563686F type=SYSCALL msg=audit(1622621131.587:692): arch=c000003e syscall=62 success=no exit=-13 a0=7b6 a1=0 a2=4 a3=7ffdd0ae746f items=0 ppid=1899 pid=2385 auid=1001 uid=0 gid=1001 euid=0 suid=0 fsuid=0 egid=1001 sgid=1001 fsgid=1001 tty=pts1 ses=17 comm="sudo" exe="/usr/bin/sudo" subj=staff_u:staff_r:staff_sudo_t:s0-s0:c0.c1023 key=(null) type=AVC msg=audit(1622621131.587:692): avc: denied { signull } for pid=2385 comm="sudo" scontext=staff_u:staff_r:staff_sudo_t:s0-s0:c0.c1023 tcontext=system_u:system_r:sshd_t:s0-s0:c0.c1023 tclass=process permissive=0 -------- 8< ---------------- 8< ---------------- 8< ---------------- 8< -------- Version-Release number of selected component (if applicable): selinux-policy-3.14.3-67.el8.noarch but also on RHEL7 How reproducible: Always Steps to Reproduce: 1. Create a confined user mapped to sysadm_u or staff_u # useradd -Z staff_u -G wheel staff # echo "redhat" | passwd --stdin staff 2. Create a "maxlogins" limit file # echo "* hard maxlogins 10" > /etc/security/limits.d/maxlogins.conf 3. Login as the staff user # ssh staff@localhost $ id -Z staff_u:staff_r:staff_t:s0-s0:c0.c1023 4. Login as the staff user in another terminal and sudo # ssh staff@localhost "sudo -u staff echo" Actual results: time->Wed Jun 2 10:15:25 2021 type=PROCTITLE msg=audit(1622621725.434:1357): proctitle=7375646F002D75007374616666006563686F type=SYSCALL msg=audit(1622621725.434:1357): arch=c000003e syscall=62 success=no exit=-13 a0=cdf a1=0 a2=4 a3=7fffed2a21ef items=0 ppid=3529 pid=3530 auid=1001 uid=0 gid=1001 euid=0 suid=0 fsuid=0 egid=1001 sgid=1001 fsgid=1001 tty=(none) ses=69 comm="sudo" exe="/usr/bin/sudo" subj=staff_u:staff_r:staff_sudo_t:s0-s0:c0.c1023 key=(null) type=AVC msg=audit(1622621725.434:1357): avc: denied { signull } for pid=3530 comm="sudo" scontext=staff_u:staff_r:staff_sudo_t:s0-s0:c0.c1023 tcontext=system_u:system_r:sshd_t:s0-s0:c0.c1023 tclass=process permissive=0 Expected results: No AVC