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gnrc_ipv6_nib: don't auto-configure IPv6 w/o SLAAC on non-6LN interface [backport 2019.10]#12522

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cgundogan merged 1 commit intoRIOT-OS:2019.10-branchfrom
miri64:backport/2019.10/gnrc_ipv6_fix/fix/auto-config-with-no-slaac-but-6ln
Oct 21, 2019
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gnrc_ipv6_nib: don't auto-configure IPv6 w/o SLAAC on non-6LN interface [backport 2019.10]#12522
cgundogan merged 1 commit intoRIOT-OS:2019.10-branchfrom
miri64:backport/2019.10/gnrc_ipv6_fix/fix/auto-config-with-no-slaac-but-6ln

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@miri64 miri64 commented Oct 21, 2019

Backport of #12513

Contribution description

When the NIB is compiled for 6LN mode (but not a 6LBR), the Stateless Address Autoconfiguration (SLAAC) functionality is disabled, as it is typically not required; see

RIOT/sys/include/net/gnrc/ipv6/nib/conf.h

Lines 41 to 48 in d9c240a

#ifdef MODULE_GNRC_IPV6_NIB_6LR
#ifndef GNRC_IPV6_NIB_CONF_6LR
#define GNRC_IPV6_NIB_CONF_6LR (1)
#endif
#ifndef GNRC_IPV6_NIB_CONF_SLAAC
#define GNRC_IPV6_NIB_CONF_SLAAC (0)
#endif
#endif

RIOT/sys/include/net/gnrc/ipv6/nib/conf.h

Lines 50 to 59 in d9c240a

#ifdef MODULE_GNRC_IPV6_NIB_6LN
#ifndef GNRC_IPV6_NIB_CONF_6LN
#define GNRC_IPV6_NIB_CONF_6LN (1)
#endif
#ifndef GNRC_IPV6_NIB_CONF_SLAAC
#define GNRC_IPV6_NIB_CONF_SLAAC (0)
#endif
#ifndef GNRC_IPV6_NIB_CONF_QUEUE_PKT
#define GNRC_IPV6_NIB_CONF_QUEUE_PKT (0)
#endif

However, if a non-6LN interface is also compiled in (still without making the node a border router) an auto-configured address will be assigned in accordance with RFC 6775 to the interface, just assuming the interface is a 6LN interface. As it then only performs duplicate address detection RFC-6775-style then, the address then never becomes valid, as the duplicate address detection according to RFC 4862 (part of the SLAAC functionality) is never performed.

As auto-configuring an address without SLAAC doesn't make sense, this fix makes the interface skip it completely, but provides a warning to the user, so they know what to do.

Testing procedure

Compile examples/gnrc_networking native with both a netdev_tap and socket_zep:

GNRC_NETIF_NUMOF=2 USEMODULE=socket_zep TERMFLAGS="-z [::]:17755 tap0" \
   make -C examples/gnrc_networking all term

With this fix, the link-local address of the Ethernet interface won't receive an auto-configured link-local address and a warning is printed

RIOT native interrupts/signals initialized.
LED_RED_OFF
LED_GREEN_ON
RIOT native board initialized.
RIOT native hardware initialization complete.

SLAAC not activated; won't auto-configure IPv6 for interface 7
    Use GNRC_IPV6_NIB_CONF_SLAAC=1 to activate
main(): This is RIOT! (Version: 2020.01-devel-197-gc93b3-gnrc_netif/enh/split-6lo-6ln)
RIOT network stack example application
All up, running the shell now
> ifconfig
ifconfig
Iface  7  HWaddr: 26:82:DC:3B:CA:E6 
          L2-PDU:1500 MTU:1500  HL:64  RTR  
          Source address length: 6
          Link type: wired
          inet6 group: ff02::2
          inet6 group: ff02::1
          
          Statistics for Layer 2
            RX packets 4  bytes 440
            TX packets 3 (Multicast: 3)  bytes 186
            TX succeeded 3 errors 0
          Statistics for IPv6
            RX packets 4  bytes 384
            TX packets 3 (Multicast: 3)  bytes 144
            TX succeeded 3 errors 0

Iface  8  HWaddr: 45:5B  Channel: 26  NID: 0x23
          Long HWaddr: 00:5A:45:50:0A:00:45:5B 
          L2-PDU:102 MTU:1280  HL:64  RTR  
          6LO  IPHC  
          Source address length: 8
          Link type: wireless
          inet6 addr: fe80::25a:4550:a00:455b  scope: local  VAL
          inet6 group: ff02::2
          inet6 group: ff02::1
          inet6 group: ff02::1:ff00:455b
          
          Statistics for Layer 2
            RX packets 0  bytes 0
            TX packets 3 (Multicast: 3)  bytes 86
            TX succeeded 6 errors 0
          Statistics for IPv6
            RX packets 0  bytes 0
            TX packets 3 (Multicast: 3)  bytes 192
            TX succeeded 3 errors 0

Compiling with CFLAGS+=-DGNRC_IPV6_NIB_CONF_SLAAC=1 still auto-configures the address and validates it shortly after the node started (and the warning is not shown ;-)):

> ifconfig
ifconfig
Iface  7  HWaddr: 26:82:DC:3B:CA:E6 
          L2-PDU:1500 MTU:1500  HL:64  RTR  
          Source address length: 6
          Link type: wired
          inet6 addr: fe80::2482:dcff:fe3b:cae6  scope: local  VAL
          inet6 group: ff02::2
          inet6 group: ff02::1
          inet6 group: ff02::1:ff3b:cae6
          
          Statistics for Layer 2
            RX packets 5  bytes 526
            TX packets 2 (Multicast: 2)  bytes 140
            TX succeeded 2 errors 0
          Statistics for IPv6
            RX packets 5  bytes 456
            TX packets 2 (Multicast: 2)  bytes 112
            TX succeeded 2 errors 0

Iface  8  HWaddr: 45:5B  Channel: 26  NID: 0x23
          Long HWaddr: 00:5A:45:50:0A:00:45:5B 
          L2-PDU:102 MTU:1280  HL:64  RTR  
          6LO  IPHC  
          Source address length: 8
          Link type: wireless
          inet6 addr: fe80::25a:4550:a00:455b  scope: local  VAL
          inet6 group: ff02::2
          inet6 group: ff02::1
          inet6 group: ff02::1:ff00:455b
          
          Statistics for Layer 2
            RX packets 0  bytes 0
            TX packets 2 (Multicast: 2)  bytes 43
            TX succeeded 3 errors 0
          Statistics for IPv6
            RX packets 0  bytes 0
            TX packets 2 (Multicast: 2)  bytes 128
            TX succeeded 2 errors 0

Without the fix and CFLAGS=-DGNRC_IPV6_NIB_CONF_SLAAC=1 not set the Ethernet interface gets a link-local address which will stay tentative forever:

> ifconfig
ifconfig
Iface  7  HWaddr: 26:82:DC:3B:CA:E6 
          L2-PDU:1500 MTU:1500  HL:64  RTR  
          Source address length: 6
          Link type: wired
          inet6 addr: fe80::2482:dcff:fe3b:cae6  scope: local  TNT[1]
          inet6 group: ff02::2
          inet6 group: ff02::1
          inet6 group: ff02::1:ff3b:cae6
          
          Statistics for Layer 2
            RX packets 5  bytes 526
            TX packets 1 (Multicast: 1)  bytes 62
            TX succeeded 1 errors 0
          Statistics for IPv6
            RX packets 5  bytes 456
            TX packets 1 (Multicast: 1)  bytes 48
            TX succeeded 1 errors 0

Iface  8  HWaddr: 45:5B  Channel: 26  NID: 0x23
          Long HWaddr: 00:5A:45:50:0A:00:45:5B 
          L2-PDU:102 MTU:1280  HL:64  RTR  
          6LO  IPHC  
          Source address length: 8
          Link type: wireless
          inet6 addr: fe80::25a:4550:a00:455b  scope: local  VAL
          inet6 group: ff02::2
          inet6 group: ff02::1
          inet6 group: ff02::1:ff00:455b
          
          Statistics for Layer 2
            RX packets 0  bytes 0
            TX packets 2 (Multicast: 2)  bytes 43
            TX succeeded 3 errors 0
          Statistics for IPv6
            RX packets 0  bytes 0
            TX packets 2 (Multicast: 2)  bytes 128
            TX succeeded 2 errors 0

Issues/PRs references

Several, but triggered by testing procedures in #12512 and #10499.

@miri64
gnrc_ipv6_nib: don't auto-configure IPv6 w/o SLAAC on non-6LN interface
dc88243 
When the NIB is compiled for 6LN mode (but not a 6LBR), the Stateless
Address Autoconfiguration (SLAAC) functionality is disabled, as it is
typically not required; see `sys/include/net/gnrc/ipv6/nib/conf.h`, ll.
46 and 55. However, if a non-6LN interface is also compiled in (still
without making the node a border router) an auto-configured address will
be assigned in accordance with [RFC 6775] to the interface, just
assuming the interface is a 6LN interface. As it then only performs
duplicate address detection RFC-6775-style then, the address then never
becomes valid, as the duplicate address detection according to [RFC
4862] (part of the SLAAC functionality) is never performed.

As auto-configuring an address without SLAAC doesn't make sense, this
fix makes the interface skip it completely, but provides a warning to
the user, so they know what to do.

[RFC 6775]: https://tools.ietf.org/html/rfc6775#section-5.2
[RFC 4862]: https://tools.ietf.org/html/rfc4862#section-5.4

(cherry picked from commit 7cba2fb)
@miri64 miri64 added Area: network Area: Networking CI: ready for build If set, CI server will compile all applications for all available boards for the labeled PR Process: release backport Integration Process: The PR is a release backport of a change previously provided to master Type: bug The issue reports a bug / The PR fixes a bug (including spelling errors) labels Oct 21, 2019
@miri64 miri64 requested a review from cgundogan October 21, 2019 07:46
@miri64 miri64 mentioned this pull request Oct 21, 2019
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@miri64 miri64 added this to the Release 2019.10 milestone Oct 21, 2019
@miri64 miri64 mentioned this pull request Oct 21, 2019
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@cgundogan cgundogan added Reviewed: 1-fundamentals The fundamentals of the PR were reviewed according to the maintainer guidelines Reviewed: 2-code-design The code design of the PR was reviewed according to the maintainer guidelines Reviewed: 3-testing The PR was tested according to the maintainer guidelines Reviewed: 4-code-style The adherence to coding conventions by the PR were reviewed according to the maintainer guidelines Reviewed: 5-documentation The documentation details of the PR were reviewed according to the maintainer guidelines labels Oct 21, 2019
cgundogan
cgundogan approved these changes Oct 21, 2019
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ACK

@cgundogan cgundogan merged commit 5648ab9 into RIOT-OS:2019.10-branch Oct 21, 2019
@miri64 miri64 deleted the backport/2019.10/gnrc_ipv6_fix/fix/auto-config-with-no-slaac-but-6ln branch October 21, 2019 08:46
@kb2ma kb2ma mentioned this pull request Oct 22, 2019
Closed
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miri64 added a commit to RIOT-OS/Release-Specs that referenced this pull request Oct 24, 2019
@miri64
spec10/task07: activate SLAAC
9382944 
Addresses the upstream fix in RIOT-OS/RIOT#12522
@miri64 miri64 mentioned this pull request Oct 24, 2019
Merged
@miri64 miri64 restored the backport/2019.10/gnrc_ipv6_fix/fix/auto-config-with-no-slaac-but-6ln branch October 31, 2019 18:50
@miri64 miri64 deleted the backport/2019.10/gnrc_ipv6_fix/fix/auto-config-with-no-slaac-but-6ln branch October 31, 2019 18:51
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Area: network Area: Networking CI: ready for build If set, CI server will compile all applications for all available boards for the labeled PR Process: release backport Integration Process: The PR is a release backport of a change previously provided to master Reviewed: 1-fundamentals The fundamentals of the PR were reviewed according to the maintainer guidelines Reviewed: 2-code-design The code design of the PR was reviewed according to the maintainer guidelines Reviewed: 3-testing The PR was tested according to the maintainer guidelines Reviewed: 4-code-style The adherence to coding conventions by the PR were reviewed according to the maintainer guidelines Reviewed: 5-documentation The documentation details of the PR were reviewed according to the maintainer guidelines Type: bug The issue reports a bug / The PR fixes a bug (including spelling errors)

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