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Bug 1997182 - Need to allow haproxy_t self:unix_stream_socket connectto
Summary: Need to allow haproxy_t self:unix_stream_socket connectto
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 9
Classification: Red Hat
Component: selinux-policy
Version: 9.0
Hardware: All
OS: Linux
medium
medium
Target Milestone: rc
: 9.0
Assignee: Zdenek Pytela
QA Contact: Amith
URL:
Whiteboard:
Depends On:
Blocks: 2015423
TreeView+ depends on / blocked
 
Reported: 2021-08-24 14:51 UTC by Ryan O'Hara
Modified: 2022-05-17 16:10 UTC (History)
4 users (show)

Fixed In Version: selinux-policy-34.1.16-1.el9
Doc Type: No Doc Update
Doc Text:
Clone Of:
: 2015423 (view as bug list)
Environment:
Last Closed: 2022-05-17 15:49:27 UTC
Type: Bug
Target Upstream Version:
Embargoed:
pm-rhel: mirror+

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Bugzilla 1986823 1 None None None 2023-09-09 15:01:37 UTC
Red Hat Issue Tracker RHELPLAN-94644 0 None None None 2021-08-24 14:54:00 UTC
Red Hat Product Errata RHBA-2022:3918 0 None None None 2022-05-17 15:49:39 UTC

Description Ryan O'Hara 2021-08-24 14:51:57 UTC 
HAProxy has long had a feature for "hitless reloads" [1] that prevents established connections from being dropped due to a reload. The way to achieve this is the setup a stats socket with keyword 'expose-fd listeners':

    stats socket /var/run/haproxy.sock mode 600 expose-fd listeners level user

However, this will trigger an AVC when reload occurs due to haproxy itself not being able to connect to the stats socket:

    # systemctl start haproxy
    # systemctl reload haproxy

Now, checking audit.log:

    # grep denied /var/log/audit/audit.log
type=AVC msg=audit(1629815894.374:1139): avc:  denied  { read } for  pid=11431 comm="haproxy" name="node" dev="sysfs" ino=614 scontext=system_u:system_r:haproxy_t:s0 tcontext=system_u:object_r:sysfs_t:s0 tclass=dir permissive=0
type=AVC msg=audit(1629815894.378:1140): avc:  denied  { connectto } for  pid=11431 comm="haproxy" path="/run/haproxy.sock" scontext=system_u:system_r:haproxy_t:s0 tcontext=system_u:system_r:haproxy_t:s0 tclass=unix_stream_socket permissive=0

    # grep denied /var/log/audit/audit.log | audit2allow 


#============= haproxy_t ==============

#!!!! This avc can be allowed using the boolean 'daemons_enable_cluster_mode'
allow haproxy_t self:unix_stream_socket connectto;
allow haproxy_t sysfs_t:dir read;

The sysfs_t:dir read AVC is due to a separate issues (see rhbz#1995256).


[1] https://www.haproxy.com/blog/hitless-reloads-with-haproxy-howto/
Comment 1 Ryan O'Hara 2021-08-24 15:47:50 UTC 
Note that enabling the 'daemons_enable_cluster_mode' boolean will resolve this problem, but I am no sure that is the preferred solution since customers will likely expect this feature to work by default. Interested to hear what selinux team has to say on this.
Comment 2 Milos Malik 2021-08-26 18:39:41 UTC 
# rpm -qa selinux\* haproxy\* | sort
haproxy-2.4.3-1.el9.x86_64
selinux-policy-34.1.13-1.el9.noarch
selinux-policy-devel-34.1.13-1.el9.noarch
selinux-policy-targeted-34.1.13-1.el9.noarch
#

The following SELinux denial appeared in enforcing mode:
----
type=PROCTITLE msg=audit(08/26/2021 14:33:22.862:375) : proctitle=/usr/sbin/haproxy -Ws -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid 
type=PATH msg=audit(08/26/2021 14:33:22.862:375) : item=0 name=/var/run/haproxy.sock inode=1216 dev=00:19 mode=socket,600 ouid=root ogid=root rdev=00:00 obj=system_u:object_r:haproxy_var_run_t:s0 nametype=NORMAL cap_fp=none cap_fi=none cap_fe=0 cap_fver=0 cap_frootid=0 
type=CWD msg=audit(08/26/2021 14:33:22.862:375) : cwd=/ 
type=SOCKADDR msg=audit(08/26/2021 14:33:22.862:375) : saddr={ saddr_fam=local path=/var/run/haproxy.sock } 
type=SYSCALL msg=audit(08/26/2021 14:33:22.862:375) : arch=x86_64 syscall=connect success=no exit=EACCES(Permission denied) a0=0x7 a1=0x7ffdf7dd6120 a2=0x6e a3=0x66 items=1 ppid=1 pid=16778 auid=unset uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=(none) ses=unset comm=haproxy exe=/usr/sbin/haproxy subj=system_u:system_r:haproxy_t:s0 key=(null) 
type=AVC msg=audit(08/26/2021 14:33:22.862:375) : avc:  denied  { connectto } for  pid=16778 comm=haproxy path=/run/haproxy.sock scontext=system_u:system_r:haproxy_t:s0 tcontext=system_u:system_r:haproxy_t:s0 tclass=unix_stream_socket permissive=0 
----

The same SELinux denial appeared in permissive mode:
----
type=PROCTITLE msg=audit(08/26/2021 14:35:03.289:386) : proctitle=/usr/sbin/haproxy -sf 21584 -x /var/run/haproxy.sock -Ws -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid 
type=PATH msg=audit(08/26/2021 14:35:03.289:386) : item=0 name=/var/run/haproxy.sock inode=1234 dev=00:19 mode=socket,600 ouid=root ogid=root rdev=00:00 obj=system_u:object_r:haproxy_var_run_t:s0 nametype=NORMAL cap_fp=none cap_fi=none cap_fe=0 cap_fver=0 cap_frootid=0 
type=CWD msg=audit(08/26/2021 14:35:03.289:386) : cwd=/ 
type=SOCKADDR msg=audit(08/26/2021 14:35:03.289:386) : saddr={ saddr_fam=local path=/var/run/haproxy.sock } 
type=SYSCALL msg=audit(08/26/2021 14:35:03.289:386) : arch=x86_64 syscall=connect success=yes exit=0 a0=0x7 a1=0x7ffde0c13fe0 a2=0x6e a3=0x66 items=1 ppid=1 pid=21582 auid=unset uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=(none) ses=unset comm=haproxy exe=/usr/sbin/haproxy subj=system_u:system_r:haproxy_t:s0 key=(null) 
type=AVC msg=audit(08/26/2021 14:35:03.289:386) : avc:  denied  { connectto } for  pid=21582 comm=haproxy path=/run/haproxy.sock scontext=system_u:system_r:haproxy_t:s0 tcontext=system_u:system_r:haproxy_t:s0 tclass=unix_stream_socket permissive=1 
----

@QA: The reload operation is necessary. These AVCs do not appear without reloading of the haproxy service.
Comment 4 Zdenek Pytela 2021-09-21 17:41:55 UTC 
(In reply to Ryan O'Hara from comment #1)
> Note that enabling the 'daemons_enable_cluster_mode' boolean will resolve
> this problem, but I am no sure that is the preferred solution since
> customers will likely expect this feature to work by default. Interested to
> hear what selinux team has to say on this.
Setroubleshoot is able to find a way how to allow the permission, it is unable to assess though if the access is not overpermissive. It is.

# sesearch -A -b daemons_enable_cluster_modee
allow daemon cluster_conf_t:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink write }; [ daemons_enable_cluster_mode ]:True
...a few dozen lines follow

I've submitted a Fedora PR to address the issue:
https://github.com/fedora-selinux/selinux-policy/pull/881
Comment 6 Zdenek Pytela 2021-09-23 12:22:16 UTC 
Commit to backport:
commit b430a991f8eb0d0a4d593ec88e07144d5cb79cdf (HEAD -> rawhide, upstream/rawhide)
Author: Zdenek Pytela <zpytela>
Date:   Tue Sep 21 19:35:22 2021 +0200

    Support hitless reloads feature in haproxy
Comment 20 errata-xmlrpc 2022-05-17 15:49:27 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 (new packages: selinux-policy), 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-2022:3918
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