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Bug 2028379 - lldpd with option to use tcp is not allowed to create a tcp socket
Summary: lldpd with option to use tcp is not allowed to create a tcp socket
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 8
Classification: Red Hat
Component: selinux-policy
Version: 8.4
Hardware: All
OS: Linux
medium
medium
Target Milestone: rc
: 8.6
Assignee: Zdenek Pytela
QA Contact: Milos Malik
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2021-12-02 09:18 UTC by Welterlen Benoit
Modified: 2022-05-10 16:24 UTC (History)
3 users (show)

Fixed In Version: selinux-policy-3.14.3-85.el8
Doc Type: Bug Fix
Doc Text:
Clone Of:
: 2028561 (view as bug list)
Environment:
Last Closed: 2022-05-10 15:15:45 UTC
Type: Bug
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Issue Tracker RHELPLAN-104529 0 None None None 2021-12-02 09:19:47 UTC
Red Hat Product Errata RHBA-2022:1995 0 None None None 2022-05-10 15:16:08 UTC

Description Welterlen Benoit 2021-12-02 09:18:15 UTC 
Description of problem:

When using these options in /etc/sysconfig/lldpd, lldpd tries to create a tcp socket instead of udp:
---
LLDPD_OPTIONS="-i -k -X tcp:127.0.0.1:705"
---

- The AVC is:
---
type=1400 msg=audit(1636718760.332:12259730): pid=2754 comm=lldpd scontext=system_u:system_r:lldpad_t:s0 tcontext=system_u:system_r:lldpad_t:s0 tclass=tcp_socket permissive=0
---

- lldpd is allowed for udp socket:
---
sesearch -A -s lldpad_t -t lldpad_t | grep sock
allow daemon daemon:unix_stream_socket connectto; [ daemons_enable_cluster_mode ]:True
allow lldpad_t lldpad_t:netlink_route_socket { append bind connect create getattr getopt ioctl lock nlmsg_read nlmsg_write read setattr setopt shutdown write };
allow lldpad_t lldpad_t:packet_socket { append bind connect create getattr getopt ioctl lock read setattr setopt shutdown write };
allow lldpad_t lldpad_t:udp_socket { append bind connect create getattr getopt ioctl lock read setattr setopt shutdown write };
allow lldpad_t lldpad_t:unix_dgram_socket { append bind connect create getattr getopt ioctl lock read setattr setopt shutdown write };
allow lldpad_t lldpad_t:unix_stream_socket { accept append bind connect connectto create getattr getopt ioctl listen lock read setattr setopt shutdown write };
---

Version-Release number of selected component (if applicable):
RHEL 8.4

How reproducible:
always

Steps to Reproduce:
1. configure lldpd with LLDPD_OPTIONS="-i -k -X tcp:127.0.0.1:705"
2.
3.

Actual results:
AVC and lldpd not allowed to create tcp socket

Expected results:
No AVC and lldpd allowed to run

Additional info:
Comment 1 Zdenek Pytela 2021-12-02 10:01:45 UTC 
I've submitted a Fedora PR to address the issue:
https://github.com/fedora-selinux/selinux-policy/pull/960
Comment 2 Welterlen Benoit 2021-12-02 10:04:22 UTC 
submitted this module to the customer:

---
policy_module(local_lldpad_tcp, 1.0)
  
gen_require(`
        type lldpad_t;
')

allow lldpad_t self:tcp_socket { create_socket_perms accept listen };
---
Comment 3 Zdenek Pytela 2021-12-02 11:26:58 UTC 
Note access to agentx_port_t will be required to add, too.
It's mentioned in the daemon man page.
Comment 4 Milos Malik 2021-12-02 13:26:34 UTC 
# rpm -qa selinux\* lldpd\* | sort
lldpd-1.0.1-2.el8.x86_64
selinux-policy-3.14.3-83.el8.noarch
selinux-policy-targeted-3.14.3-83.el8.noarch
#

Following SELinux denial appears in enforcing mode:
----
type=PROCTITLE msg=audit(12/02/2021 08:23:32.888:328) : proctitle=/usr/sbin/lldpd -i -k -X tcp:127.0.0.1:705 
type=SYSCALL msg=audit(12/02/2021 08:23:32.888:328) : arch=x86_64 syscall=socket success=no exit=EACCES(Permission denied) a0=inet a1=SOCK_STREAM a2=ip a3=0x0 items=0 ppid=5499 pid=5501 auid=unset uid=lldpd gid=lldpd euid=lldpd suid=lldpd fsuid=lldpd egid=lldpd sgid=lldpd fsgid=lldpd tty=(none) ses=unset comm=lldpd exe=/usr/sbin/lldpd subj=system_u:system_r:lldpad_t:s0 key=(null) 
type=AVC msg=audit(12/02/2021 08:23:32.888:328) : avc:  denied  { create } for  pid=5501 comm=lldpd scontext=system_u:system_r:lldpad_t:s0 tcontext=system_u:system_r:lldpad_t:s0 tclass=tcp_socket permissive=0 
----

Following SELinux denials appear in permissive mode:
----
type=PROCTITLE msg=audit(12/02/2021 08:24:45.363:336) : proctitle=/usr/sbin/lldpd -i -k -X tcp:127.0.0.1:705 
type=SYSCALL msg=audit(12/02/2021 08:24:45.363:336) : arch=x86_64 syscall=socket success=yes exit=16 a0=inet a1=SOCK_STREAM a2=ip a3=0x0 items=0 ppid=5543 pid=5545 auid=unset uid=lldpd gid=lldpd euid=lldpd suid=lldpd fsuid=lldpd egid=lldpd sgid=lldpd fsgid=lldpd tty=(none) ses=unset comm=lldpd exe=/usr/sbin/lldpd subj=system_u:system_r:lldpad_t:s0 key=(null) 
type=AVC msg=audit(12/02/2021 08:24:45.363:336) : avc:  denied  { create } for  pid=5545 comm=lldpd scontext=system_u:system_r:lldpad_t:s0 tcontext=system_u:system_r:lldpad_t:s0 tclass=tcp_socket permissive=1 
----
type=PROCTITLE msg=audit(12/02/2021 08:24:45.363:337) : proctitle=/usr/sbin/lldpd -i -k -X tcp:127.0.0.1:705 
type=SOCKADDR msg=audit(12/02/2021 08:24:45.363:337) : saddr={ saddr_fam=inet laddr=127.0.0.1 lport=705 } 
type=SYSCALL msg=audit(12/02/2021 08:24:45.363:337) : arch=x86_64 syscall=connect success=no exit=ECONNREFUSED(Connection refused) a0=0x10 a1=0x7fff4b141570 a2=0x10 a3=0x0 items=0 ppid=5543 pid=5545 auid=unset uid=lldpd gid=lldpd euid=lldpd suid=lldpd fsuid=lldpd egid=lldpd sgid=lldpd fsgid=lldpd tty=(none) ses=unset comm=lldpd exe=/usr/sbin/lldpd subj=system_u:system_r:lldpad_t:s0 key=(null) 
type=AVC msg=audit(12/02/2021 08:24:45.363:337) : avc:  denied  { name_connect } for  pid=5545 comm=lldpd dest=705 scontext=system_u:system_r:lldpad_t:s0 tcontext=system_u:object_r:agentx_port_t:s0 tclass=tcp_socket permissive=1 
type=AVC msg=audit(12/02/2021 08:24:45.363:337) : avc:  denied  { connect } for  pid=5545 comm=lldpd scontext=system_u:system_r:lldpad_t:s0 tcontext=system_u:system_r:lldpad_t:s0 tclass=tcp_socket permissive=1 
----
Comment 5 Milos Malik 2021-12-02 15:16:01 UTC 
If the snmpd service is running and is configured in the following way:

# tail -n 3 /etc/snmp/snmpd.conf 
master agentx
agentXSocket tcp:localhost:705

#

then the restart of lldpd service triggers an additional SELinux denial:
----
type=PROCTITLE msg=audit(12/02/2021 10:12:04.979:464) : proctitle=/usr/sbin/lldpd -i -k -X tcp:127.0.0.1:705 
type=SYSCALL msg=audit(12/02/2021 10:12:04.979:464) : arch=x86_64 syscall=getsockopt success=yes exit=0 a0=0x10 a1=SOL_SOCKET a2=SO_SNDBUF a3=0x7ffd61d3d590 items=0 ppid=7386 pid=7388 auid=unset uid=lldpd gid=lldpd euid=lldpd suid=lldpd fsuid=lldpd egid=lldpd sgid=lldpd fsgid=lldpd tty=(none) ses=unset comm=lldpd exe=/usr/sbin/lldpd subj=system_u:system_r:lldpad_t:s0 key=(null) 
type=AVC msg=audit(12/02/2021 10:12:04.979:464) : avc:  denied  { getopt } for  pid=7388 comm=lldpd laddr=127.0.0.1 lport=58606 faddr=127.0.0.1 fport=705 scontext=system_u:system_r:lldpad_t:s0 tcontext=system_u:system_r:lldpad_t:s0 tclass=tcp_socket permissive=1 
----
Comment 7 Zdenek Pytela 2021-12-02 16:14:35 UTC 
(In reply to Zdenek Pytela from comment #3)
> It's mentioned in the daemon man page.

I should have been more clear here.
lldpd(8) explicitly mentions tcp socket usage on port 705:

     -X socket
             Enable SNMP subagent using the specified socket.  lldpd will enable an SNMP sub-
             agent using AgentX protocol for the given socket. This option implies the previous
             one. The default socket is usually /var/agentx/master.  You can specify a socket
             like tcp:127.0.0.1:705 for example. Since the process that will open this socket is
             enclosed in a chroot, you need to specify an IP address (not a hostname) when using
             a TCP or UDP socket.

so it makes sense allow both permission groups.

All the AVC denials found should be addressed by the existing commit.
Comment 9 Zdenek Pytela 2021-12-06 16:06:39 UTC 
To backport:
commit c0b38cf988df48613209e48007eefd748480d52f (HEAD -> rawhide, upstream/rawhide, origin/rawhide, origin/HEAD)
Author: Zdenek Pytela <zpytela>
Date:   Thu Dec 2 10:55:46 2021 +0100

    Allow lldpd use an snmp subagent over a tcp socket
Comment 18 errata-xmlrpc 2022-05-10 15:15:45 UTC 
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
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