Bug 199378
| Summary: | [patch] dhclient violates RFC2131 when sending early DHCPREQUEST message to re-obtain old IP | ||||||
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| Product: | Base System | Reporter: | J.R. Oldroyd <fbsd> | ||||
| Component: | bin | Assignee: | David Bright <dab> | ||||
| Status: | Closed FIXED | ||||||
| Severity: | Affects Many People | CC: | dab | ||||
| Priority: | --- | Keywords: | patch | ||||
| Version: | CURRENT | Flags: | dab:
mfc-stable11+
dab: mfc-stable10+ |
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| Hardware: | Any | ||||||
| OS: | Any | ||||||
| Attachments: |
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A commit references this bug: Author: dab Date: Tue Feb 27 21:59:23 UTC 2018 New revision: 330085 URL: https://svnweb.freebsd.org/changeset/base/330085 Log: dhclient violates RFC2131 when sending early DHCPREQUEST message to re-obtain old IP When dhclient first starts, if an old IP address exists in the dhclient.leases file, dhclient(8) sends early DHCPREQUEST message(s) in an attempt to re-obtain the old IP address again. These messages contain the old IP as a requested-IP-address option in the message body (correct) but also use the old IP address as the packet's source IP (incorrect). RFC2131 sec 4.1 states: DHCP messages broadcast by a client prior to that client obtaining its IP address must have the source address field in the IP header set to 0. The use of the old IP as the packet's source address is incorrect if (a) the computer is now on a different network or (b) it is on the same network, but the old IP has been reallocated to another host. Fix dhclient to use 0.0.0.0 as the source IP in this circumstance without removing any existing functionality. Any previously-used old IP is still requested in the body of an early DHCPREQUEST message. PR: 199378 Submitted by: J.R. Oldroyd <fbsd@opal.com> Reported by: J.R. Oldroyd <fbsd@opal.com> Reviewed by: cem, asomers, vangyzen MFC after: 1 week Sponsored by: Dell EMC Differential Revision: https://reviews.freebsd.org/D14527 Changes: head/sbin/dhclient/dhclient.c A commit references this bug: Author: dab Date: Fri Mar 9 14:38:47 UTC 2018 New revision: 330692 URL: https://svnweb.freebsd.org/changeset/base/330692 Log: MFC r330085: dhclient violates RFC2131 when sending early DHCPREQUEST message to re-obtain old IP When dhclient first starts, if an old IP address exists in the dhclient.leases file, dhclient(8) sends early DHCPREQUEST message(s) in an attempt to re-obtain the old IP address again. These messages contain the old IP as a requested-IP-address option in the message body (correct) but also use the old IP address as the packet's source IP (incorrect). RFC2131 sec 4.1 states: DHCP messages broadcast by a client prior to that client obtaining its IP address must have the source address field in the IP header set to 0. The use of the old IP as the packet's source address is incorrect if (a) the computer is now on a different network or (b) it is on the same network, but the old IP has been reallocated to another host. Fix dhclient to use 0.0.0.0 as the source IP in this circumstance without removing any existing functionality. Any previously-used old IP is still requested in the body of an early DHCPREQUEST message. PR: 199378 Submitted by: J.R. Oldroyd <fbsd@opal.com> Reported by: J.R. Oldroyd <fbsd@opal.com> Sponsored by: Dell EMC Changes: _U stable/11/ stable/11/sbin/dhclient/dhclient.c A commit references this bug: Author: dab Date: Fri Mar 9 14:39:29 UTC 2018 New revision: 330693 URL: https://svnweb.freebsd.org/changeset/base/330693 Log: MFC r330085: dhclient violates RFC2131 when sending early DHCPREQUEST message to re-obtain old IP When dhclient first starts, if an old IP address exists in the dhclient.leases file, dhclient(8) sends early DHCPREQUEST message(s) in an attempt to re-obtain the old IP address again. These messages contain the old IP as a requested-IP-address option in the message body (correct) but also use the old IP address as the packet's source IP (incorrect). RFC2131 sec 4.1 states: DHCP messages broadcast by a client prior to that client obtaining its IP address must have the source address field in the IP header set to 0. The use of the old IP as the packet's source address is incorrect if (a) the computer is now on a different network or (b) it is on the same network, but the old IP has been reallocated to another host. Fix dhclient to use 0.0.0.0 as the source IP in this circumstance without removing any existing functionality. Any previously-used old IP is still requested in the body of an early DHCPREQUEST message. PR: 199378 Submitted by: J.R. Oldroyd <fbsd@opal.com> Reported by: J.R. Oldroyd <fbsd@opal.com> Sponsored by: Dell EMC Changes: _U stable/10/ stable/10/sbin/dhclient/dhclient.c |
Created attachment 155476 [details] patch to cause early DHCPREQUEST broadcasts to be sent using source IP 0.0.0.0 When dhclient first starts, if an old IP address exists in the dhclient.leases file, dhclient(8) sends early DHCPREQUEST message(s) in an attempt to re-obtain the old IP address again. These messages contain the old IP as a requested-IP-address option in the message body (correct) but the message also uses the old IP address as the packet's source IP (incorrect). RFC2131 sec 4.1 states: DHCP messages broadcast by a client prior to that client obtaining its IP address must have the source address field in the IP header set to 0. The use of the old IP as the packet's source address is incorrect if (a) the computer is now on a different network or (b) it is on the same network, but the old IP has been reallocated to another host. The attached patch fixes things to use 0.0.0.0 as the source IP without removing any existing functionality. Any previously-used old IP is still requested in the body of an early DHCPREQUEST message.