Created attachment 691423 [details] selinux policy with passwd rootok commented out Description of problem: I needed to use /usr/bin/su in cups backend. I enabled debug using semodule -BD. I went througth: grep pool /var/log/audit/audit.log | audit2allow -M test semodule -i test I reached the point where no relevant AVC denied is in audit.log. However it didn't work with setenforce 1 and it worked with setenforce 0. The only log entry in audit.log about failure was: type=USER_AUTH msg=audit(1359570266.199:3008): pid=9453 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:cupsd_t:s0-s0:c0.c1023 msg='op=PAM:authentication acct="luf" exe="/usr/bin/su" hostname=? addr=? terminal=? res=failed' I tracked the problem to pam module pam_rootok.so (/var/log/secure). setenfroce 0: Jan 30 19:59:56 hurvajs su: pam_rootok(su:auth): root check succeeded setenforce 1: Jan 30 20:28:38 hurvajs su: pam_rootok(su:auth): root check failed pam_rootok is compiled with selinux and the affected line is: #ifdef WITH_SELINUX if (is_selinux_enabled()<1 || checkPasswdAccess(PASSWD__ROOTOK)==0) #endif I got advice on linux to try: allow cupsd_t self:passwd rootok; This helps me. I think it should be logged in audit.log (when semodule -BD). Version-Release number of selected component (if applicable): cups-1.5.4-20.fc18 pam-1.1.6-3.fc18 selinux-policy-3.11.1-73.fc18 How reproducible: Redefine smb cups backend, define some fake printer and try to print on the printer. Steps to Reproduce: 1. rm -f /usr/lib/cups/backend/smb 2. cat > /usr/lib/cups/backend/smb <<EOF #!/bin/sh echo 'network smb "Unknown" "Windows Printer via SAMBA"' /bin/su -c "/usr/bin/logger 'CUPS /bin/su works'" $2 EOF 3. load attached selinux policy 4. enable debug semodule -BD 5. setenforce 1 6. create cups printer using smb backend 7. print to the created printer Actual results: No information about failed rootok check in audit.log Expected results: Some audit.log entry of this form: type=USER_AVC msg=audit(<timestamp>): avc: denied { rootok } for pid=.. comm=".." scontext=system_u:system_r:cupsd_t:s0-s0:c0.c1023 tcontext=... tclass=passwd Additional info:
This is a pam_rootok bug. It needs to generate the SELinux AVC message.
Dan, I'd like to implement similar code as in passwd. Is the check like this correct? if ((status = getprevcon(&user_context)) < 0) return status; status = selinux_check_access(user_context, user_context, "passwd", "passwd", NULL); I'm just unsure about the getprevcon() call.
Usually pam stack is called as passwd_t, but we want to determine which context called into passwd_t, So getprevcon would tell us the context was unconfined_t, or sshd_t or staff_t. Then we want to check to see if these users are allowed to change a password with providing their password. In the case of pam, I think you would just use getcon()
*** Bug 965723 has been marked as a duplicate of this bug. ***
pam-1.1.6-4.fc18 has been submitted as an update for Fedora 18. https://admin.fedoraproject.org/updates/pam-1.1.6-4.fc18
pam-1.1.6-12.fc19 has been submitted as an update for Fedora 19. https://admin.fedoraproject.org/updates/pam-1.1.6-12.fc19
Package pam-1.1.6-12.fc19: * should fix your issue, * was pushed to the Fedora 19 testing repository, * should be available at your local mirror within two days. Update it with: # su -c 'yum update --enablerepo=updates-testing pam-1.1.6-12.fc19' as soon as you are able to. Please go to the following url: https://admin.fedoraproject.org/updates/FEDORA-2013-12889/pam-1.1.6-12.fc19 then log in and leave karma (feedback).
pam-1.1.6-12.fc19 has been pushed to the Fedora 19 stable repository. If problems still persist, please make note of it in this bug report.
pam-1.1.6-4.fc18 has been pushed to the Fedora 18 stable repository. If problems still persist, please make note of it in this bug report.