Bug 615083 - SELinux is preventing /sbin/iptables-multi access to a leaked /root/iptables-default.txt file descriptor.
Summary: SELinux is preventing /sbin/iptables-multi access to a leaked /root/iptables-...
Alias: None
Product: Fedora
Classification: Fedora
Component: selinux-policy   
(Show other bugs)
Version: 13
Hardware: i386 Linux
Target Milestone: ---
Assignee: Daniel Walsh
QA Contact: Fedora Extras Quality Assurance
Whiteboard: setroubleshoot_trace_hash:19e770d9cbb...
Depends On:
TreeView+ depends on / blocked
Reported: 2010-07-15 21:27 UTC by mdeggers
Modified: 2010-09-15 12:27 UTC (History)
3 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
Last Closed: 2010-07-19 08:37:51 UTC
Type: ---
Regression: ---
Mount Type: ---
Documentation: ---
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

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Description mdeggers 2010-07-15 21:27:30 UTC

SELinux is preventing /sbin/iptables-multi access to a leaked
/root/iptables-default.txt file descriptor.

Detailed Description:

[SELinux is in permissive mode. This access was not denied.]

SELinux denied access requested by the iptables-save command. It looks like this
is either a leaked descriptor or iptables-save output was redirected to a file
it is not allowed to access. Leaks usually can be ignored since SELinux is just
closing the leak and reporting the error. The application does not use the
descriptor, so it will run properly. If this is a redirection, you will not get
output in the /root/iptables-default.txt. You should generate a bugzilla on
selinux-policy, and it will get routed to the appropriate package. You can
safely ignore this avc.

Allowing Access:

You can generate a local policy module to allow this access - see FAQ

Additional Information:

Source Context                unconfined_u:unconfined_r:iptables_t:s0
Target Context                unconfined_u:object_r:admin_home_t:s0
Target Objects                /root/iptables-default.txt [ file ]
Source                        iptables-save
Source Path                   /sbin/iptables-multi
Port                          <Unknown>
Host                          (removed)
Source RPM Packages           iptables-1.4.7-2.fc13
Target RPM Packages           
Policy RPM                    selinux-policy-3.7.19-33.fc13
Selinux Enabled               True
Policy Type                   targeted
Enforcing Mode                Permissive
Plugin Name                   leaks
Host Name                     (removed)
Platform                      Linux (removed)
                              #1 SMP Tue Jul 6 22:30:55 UTC 2010 i686 i686
Alert Count                   1
First Seen                    Thu 15 Jul 2010 02:25:42 PM PDT
Last Seen                     Thu 15 Jul 2010 02:25:42 PM PDT
Local ID                      9f7aff4a-7ff0-4252-92d2-123c83aafa73
Line Numbers                  

Raw Audit Messages            

node=(removed) type=AVC msg=audit(1279229142.637:59): avc:  denied  { write } for  pid=6291 comm="iptables-save" path="/root/iptables-default.txt" dev=dm-0 ino=3317900 scontext=unconfined_u:unconfined_r:iptables_t:s0 tcontext=unconfined_u:object_r:admin_home_t:s0 tclass=file

node=(removed) type=SYSCALL msg=audit(1279229142.637:59): arch=40000003 syscall=11 success=yes exit=0 a0=8592d50 a1=85b0878 a2=85aa470 a3=85b0878 items=0 ppid=5109 pid=6291 auid=500 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts1 ses=1 comm="iptables-save" exe="/sbin/iptables-multi" subj=unconfined_u:unconfined_r:iptables_t:s0 key=(null)

Hash String generated from  leaks,iptables-save,iptables_t,admin_home_t,file,write
audit2allow suggests:

#============= iptables_t ==============
allow iptables_t admin_home_t:file write;

Comment 1 mdeggers 2010-07-15 21:35:16 UTC
This is on a system that was upgraded directly from Fedora 11 to Fedora 13 using pre-upgrade.

Yes, the pre-upgrade worked quite nicely. There may be some lingering SELinux file labeling issues. However, this particular issue shouldn't be one of them.

For this particular instance, I'm dumping the current iptables to a file so I can figure out how to allow multicasting applications to work. With the firewall disabled, multicasting (in this case, Tomcat 6.0.28 clustering) works as expected.

I issued the following command as root:

iptables-save > iptables-default.txt

This of course generates a nice file for me to study. It also generated the SELinux error above.

Comment 2 Miroslav Grepl 2010-07-19 08:37:51 UTC
We don't want to allow the iptables_t domain this access.

#============= iptables_t ==============
allow iptables_t admin_home_t:file write;   

A trick you could use

iptables-save | cat >  ~/somefile

Or just add the allow rule using audit2allow

# grep iptables /var/log/audit/audit.log | audit2allow -M myiptables
# semodule -i myiptables.pp

Comment 3 mdeggers 2010-07-19 18:08:37 UTC
OK. Thanks for the trick. I'll use the trick rather than adding a rule. I imagine there are security reasons for this (although I performed the initial operation as root).

Comment 4 Daniel Walsh 2010-07-19 19:39:53 UTC
mdeggers we are trying to prevent processes from writing to the /root directory.  If a process is allowed to write to the root directory than it could write ~/.bashrc.  Next time the administrator executed a shell, his machine would be taken over.

SELinux is all about controlling processes actions.  We are not concerned about securing iptables so much as the applications that have to call iptables.  For example networkmanager or dclient might need to call iptables and those apps could be confused by untrusted data downloaded from the net.  We want to do our best to make sure these apps can be confined from taking over the entire machine.

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