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Bug 1701969 - bind is unable to determine the local ephemeral port range, leading to selinux denials
Summary: bind is unable to determine the local ephemeral port range, leading to selinu...
Keywords:
Status: CLOSED DUPLICATE of bug 1683754
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: bind
Version: 7.6
Hardware: Unspecified
OS: Unspecified
unspecified
medium
Target Milestone: rc
: ---
Assignee: Petr Menšík
QA Contact: qe-baseos-daemons
URL:
Whiteboard:
Depends On: 1683754
Blocks:
TreeView+ depends on / blocked
 
Reported: 2019-04-22 15:15 UTC by Kyle Walker
Modified: 2019-06-17 15:32 UTC (History)
2 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2019-06-17 15:32:48 UTC
Target Upstream Version:
Embargoed:

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Description Kyle Walker 2019-04-22 15:15:59 UTC 
Description of problem:
 bind is unable to determine the local ephemeral port range, via the "net.ipv4.ip_local_port_range" tunable, and as a result defaults to 1024 to 65535. This results in periodic SELinux name_bind AVCs when attempting to bind to ports which other labels are applied. 

Such as the port 20514 syslogd_port_t context shown below with dontaudit rules disabled:

time->Mon Apr 22 11:10:26 2019
type=PROCTITLE msg=audit(1555945826.464:6309): proctitle=2F7573722F7362696E2F6E616D6564002D75006E616D6564002D63002F6574632F6E616D65642E636F6E66
type=SYSCALL msg=audit(1555945826.464:6309): arch=c000003e syscall=49 success=no exit=-13 a0=205 a1=7fb29380e440 a2=10 a3=12 items=0 ppid=1 pid=23570 auid=4294967295 uid=25 gid=25 euid=25 suid=25 fsuid=25 egid=25 sgid=25 fsgid=25 tty=(none) ses=4294967295 comm="named" exe="/usr/sbin/named" subj=system_u:system_r:named_t:s0 key=(null)
type=AVC msg=audit(1555945826.464:6309): avc:  denied  { name_bind } for  pid=23570 comm="named" src=20514 scontext=system_u:system_r:named_t:s0 tcontext=system_u:object_r:syslogd_port_t:s0 tclass=udp_socket permissive=0


Also visible in the system journal as the EPERM errors below:

Apr 22 11:11:56 example.com named[23570]: dispatch 0x7fb28c0b7870: open_socket(0.0.0.0#20514) -> permission denied: continuing


Version-Release number of selected component (if applicable):
 bind-9.9.4-73.el7_6.x86_64


How reproducible:
 Easily

Steps to Reproduce:
1. Start the "named" service
 # systemctl start named

2. Verify the port range for the service
 # journalctl -u named.service | grep port\ range
 Apr 22 11:13:27 example.com named[24005]: using default UDP/IPv6 port range: [1024, 65535]

Actual results:
 # journalctl -u named.service | grep port\ range
 Apr 22 11:13:27 example.com named[24005]: using default UDP/IPv6 port range: [1024, 65535]
 

Expected results:
 For a default configuration:

 # journalctl -u named.service | grep port\ range
 Apr 22 11:13:27 example.com named[24005]: using default UDP/IPv6 port range: [32768, 60999]


Additional info:
 The fix seems to have been implemented upstream in the following PR:

    4109. [port] linux: support reading the local port range from · isc-projects/bind9@e77e449
    https://github.com/isc-projects/bind9/commit/e77e44954909dd2e0af1ce724e01f4199ae1e9c0
Comment 2 Petr Menšík 2019-05-31 14:23:22 UTC 
This issue has to be fixed by selinux-policy, there is nothing I can do about it in bind. Should be already solved by bug #1683754
Comment 3 Tomáš Hozza 2019-06-17 15:32:48 UTC 

*** This bug has been marked as a duplicate of bug 1683754 ***
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