RHBA-2015:0450 - Bug Fix Advisory

Topic

Updated dhcp packages that fix several bugs are now available for Red Hat
Enterprise Linux 7.

Description

The Dynamic Host Configuration Protocol (DHCP) is a protocol that allows
individual devices on an IP network to get their own network configuration
information, including an IP address, a subnet mask, and a broadcast address.
The dhcp packages provide a relay agent and ISC DHCP service required to enable
and administer DHCP on a network.

This update fixes the following bugs:

• Previously, the "systemctl start dhcpd" command incorrectly returned a zero

exit status (implying success) when the dhcpd service actually failed to start.
This could cause a number of applications dependent on the exit status of dhcpd
to fail or not function properly. With this update, dhcpd now notifies the
initialization system when it is ready, and systemctl thus correctly returns 1
in case of a service failure. As a result, the affected applications now work as
expected. (BZ#1087245)

• Prior to this update, when a DHCPv6 server offered a client an IPv6 address

that was already in use by another machine, the dhclient utility did not send a
Decline message. This behavior is not compliant with the RFC 3315 standard. This
bug has been fixed, and dhclient now sends a Decline message as expected.
(BZ#1133465)

• Previously, the dhclient-script incorrectly handled SELinux context of certain

files. Consequently, running the IP injection script on Hyper-V 2012 (R2) host
with Red Hat Enterprise Linux 7.1 guest failed in SELinux enforcing mode. The
dhclient-script has been fixed, and IP injection is now successful in this
scenario. (BZ#1161500)

• Previously, the dhclient utility generated different DHCP Unique Identifier

Based on Link-layer Address Plus Time (DUID-LLT) each time it was started in
stateless mode (using the "-S" option in DHCPv6 mode, not requesting an
address). A patch has been applied to change this behavior, and running the
"dhclient -6 -S -D LLT" command now generates a DUID-LLT only once and writes it
in a file. As a result, DUID_LLT is the same for each run of dhclient in
stateless mode. (BZ#1156356)

• Due to a regression, DHCPv6 relay agent incorrectly handled when the "lower"

interface was specified (using the "-l" command-line option) before the "upper"
interface (using the "-u" option). As a consequence, relaying of messages did
not work. This bug has been fixed, and DHCPv6 relay agent now relays messages as
expected. (BZ#1151039)

• Previously, the dhclient utility did not properly handle when two or more

network interfaces on one machine were connected to the same subnet and at least
one of them was obtaining an IP address using DHCP. As a consequence, dhclient
incorrectly assumed the address being renewed was already in use by some other
machine and declined it. This bug in the dhclient-script has been fixed, and
dhclient now correctly renews the address in this scenario. (BZ#1116004)

• The Hop Limit for the Relay-forward messages sent by DHCPv6 Relay agent was

set to 1, which was not compliant with RFC 3315. With this update, the Hop Limit
has been correctly set to 32. (BZ#1147240)

• The chrony service is configured to use NTP servers received from DHCP. Prior

to this update, the NetworkManager dispatcher script failed to notify the chrony
service of NTP servers received from DHCP. Consequently, boot was very slow
because the system was waiting for the chrony-wait service. This bug has been
fixed, and chrony-wait no longer blocks the boot. (BZ#1093490)

Users of dhcp are advised to upgrade to these updated packages, which fix these
bugs.

Solution

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

For details on how to apply this update, refer to:

https://access.redhat.com/articles/11258

Affected Products

• Red Hat Enterprise Linux Server 7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.6 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.5 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.4 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.3 x86_64
• Red Hat Enterprise Linux Server - AUS 7.7 x86_64
• Red Hat Enterprise Linux Server - AUS 7.6 x86_64
• Red Hat Enterprise Linux Server - AUS 7.4 x86_64
• Red Hat Enterprise Linux Server - AUS 7.3 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 7 x86_64
• Red Hat Enterprise Linux Workstation 7 x86_64
• Red Hat Enterprise Linux Desktop 7 x86_64
• Red Hat Enterprise Linux for IBM z Systems 7 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.7 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.6 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.5 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.4 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.3 s390x
• Red Hat Enterprise Linux for Power, big endian 7 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.7 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.6 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.5 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.4 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.3 ppc64
• Red Hat Enterprise Linux for Scientific Computing 7 x86_64
• Red Hat Enterprise Linux Server from RHUI 7 x86_64
• Red Hat Enterprise Linux Server - TUS 7.7 x86_64
• Red Hat Enterprise Linux Server - TUS 7.6 x86_64
• Red Hat Enterprise Linux Server - TUS 7.3 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 7 s390x
• Red Hat Enterprise Linux EUS Compute Node 7.7 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.6 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.5 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.4 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.3 x86_64
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 7.7 x86_64
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 7.6 x86_64
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 7.4 x86_64
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 7.3 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support for IBM Power, big endian 7 ppc64

Fixes

• BZ - 1101149 - dhclient-script -6 ignores name-servers/domain-search in stateless DHCPv6 mode (-S)
• BZ - 1109947 - DHCP over IB: Lack of GUIDs in the DHCPD logs
• BZ - 1109949 - dhclient-script does not handle option 121 properly
• BZ - 1130803 - DHCPv6-only ifup-eth fails to even run dhclient -6 due to a link-local IPv6 address still being 'tentative'
• BZ - 1133839 - [dhclient -6] infinite preferred/valid lifetime is represented as -1
• BZ - 1145832 - service dhcpd does not start on reboot when using bridge
• BZ - 1147240 - [TAHI][DHCPv6] Test DHCP_CONF.9.1.2 Part A: Relay-forward Message's Hop Limit should be 32
• BZ - 1151039 - 'dhcrelay -6 -l <nic1> -u <nic2>' does not work
• BZ - 1156356 - [TAHI][DHCPv6] DHCP_CONF.7.1.9: found client-identifier of type DUID-LL (expected DUID-LLT) in dhcpv6 information request message
• BZ - 1161500 - [Hyper-V][REHL 7.1] IP injection fail due to SELinux denied with gen2 guest

CVEs

(none)

References

(none)