SELinux is preventing /usr/sbin/winbindd from 'write' accesses on the file /etc/pki/nssdb/key4.db. ***** Plugin catchall (100. confidence) suggests *************************** If you believe that winbindd should be allowed write access on the key4.db file 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: # grep winbindd /var/log/audit/audit.log | audit2allow -M mypol # semodule -i mypol.pp Additional Information: Source Context system_u:system_r:winbind_t:s0 Target Context system_u:object_r:cert_t:s0 Target Objects /etc/pki/nssdb/key4.db [ file ] Source winbindd Source Path /usr/sbin/winbindd Port <Unknown> Host (removed) Source RPM Packages samba-winbind-3.6.0-64pre1.fc15.1 Target RPM Packages nss-sysinit-3.12.9-13.fc16 Policy RPM selinux-policy-3.9.15-2.fc16 Selinux Enabled True Policy Type targeted Enforcing Mode Enforcing Host Name (removed) Platform Linux (removed) 2.6.38-0.rc6.git0.1.fc16.x86_64 #1 SMP Tue Feb 22 18:14:51 UTC 2011 x86_64 x86_64 Alert Count 37 First Seen Tue 22 Feb 2011 01:54:22 PM CST Last Seen Tue 01 Mar 2011 09:58:27 AM CST Local ID a1546412-a0c4-4e76-8e59-91b0d4c34dd2 Raw Audit Messages type=AVC msg=audit(1298995107.380:737): avc: denied { write } for pid=9280 comm="winbindd" name="key4.db" dev=dm-0 ino=1051941 scontext=system_u:system_r:winbind_t:s0 tcontext=system_u:object_r:cert_t:s0 tclass=file type=SYSCALL msg=audit(1298995107.380:737): arch=x86_64 syscall=open success=no exit=EACCES a0=7f4f2818d020 a1=42 a2=1a4 a3=7f4f2818d020 items=0 ppid=1 pid=9280 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=4294967295 comm=winbindd exe=/usr/sbin/winbindd subj=system_u:system_r:winbind_t:s0 key=(null) Hash: winbindd,winbind_t,cert_t,file,write audit2allow #============= winbind_t ============== allow winbind_t cert_t:file write; audit2allow -R #============= winbind_t ============== allow winbind_t cert_t:file write;
Does winbind actually need to write this file or is this an access check?
I don't know of any direct use of NSS (the crypto lib) in winbind. This must be coming by way of some other library. (openldap? krb5?)
It's hard for me to say whether it requires is or now, since it seems to be crashing a lot for me because of another bug. If I had to guess between openldap or krb5, I'd probably go with Kerberos since I'm authenticating to Active Directory with a Kerberos domain. After allowing the cert_t:file permission, it also wants cert_t:dir write. I've uploaded the winbind logs that were touched today if that will be of any help: http://www.letu.edu/people/stevenhadfield/logs/mar-2011/log.wb-LETNET http://www.letu.edu/people/stevenhadfield/logs/mar-2011/log.winbindd http://www.letu.edu/people/stevenhadfield/logs/mar-2011/log.winbindd-idmap http://www.letu.edu/people/stevenhadfield/logs/mar-2011/winbind_audit.log Let me know if there's anything else I can provide.
Eric if this was an access check would the syscall be access instead of open?
It would. This is an open(2) with a1=flags=0x42 O_RDWR = 0x02 O_CREAT = 0x40
In case it helps: In Rawhide kerberos has added support for NSS kerberos diff -up f15/krb5.spec master/krb5.spec | grep NSS %global WITH_OPENSSL 1 -%global WITH_NSS 0 +%global WITH_NSS 1 %if %{WITH_OPENSSL} +%if %{WITH_NSS} +- turn on NSS as the backend for libk5crypto, adding nss-devel as a build
Which may explain the write acces to /etc/pki/nssdb/key4.db which is the databse holding the secret and private keys. Kerberos may be generating keys. Take this witch a pinch of salt as I am not familiar with kerberos, if indeed is kerberos that's causing the access.
But access to /etc/pki/nssdb/, which is the sytem-wide database, is normally read-only, unless the process is running at root.
In this case the process is running as root. But SELinux is still denying 'write'. Obviously if opening this file with write access is correct and required for normal operation selinux policy can be relaxed to allow this to happen. But until we understand why it is happening and are certain that it happening is a good idea, policy will not be changed....
AFAIK winbindd really doesn't need access to that DB. If it is trying to open it it is probably because some library do it by default I guess. But I think winbindd should be treated like a regular user process in this regard and get only read access. However if a library open the file for read/wrote just because winbind is running as root i t looks to me that there is a bug in it that should be fixed. So finding out what library is doing that would be a good idea. I know in F-14 and later OpenLDAP libraries have been changed to use NSS instead of OpenSSL so they would be one of my candidates.
openldap opens NSS with NSS_INIT_READONLY initctx = NSS_InitContext( realcertdir, prefix, prefix, SECMOD_DB, &initParams, NSS_INIT_READONLY ); or int flags = NSS_INIT_READONLY|NSS_INIT_NOCERTDB|NSS_INIT_NOMODDB; ... initctx = NSS_InitContext( "", "", "", SECMOD_DB, &initParams, flags );
Well we can certainly dont audit it. I know kerberos does wacky things like determining what access it has to a file, but I thought it did this via access.
This bug appears to have been reported against 'rawhide' during the Fedora 19 development cycle. Changing version to '19'. (As we did not run this process for some time, it could affect also pre-Fedora 19 development cycle bugs. We are very sorry. It will help us with cleanup during Fedora 19 End Of Life. Thank you.) More information and reason for this action is here: https://fedoraproject.org/wiki/BugZappers/HouseKeeping/Fedora19
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