buglwIP - A Lightweight TCP/IP stack - Bugs: bug #47921, link-local prefix in router...

 
 

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bug #47921: link-local prefix in router advertisement must not be processes for SLAAC

Submitter:  abhishek ambure <abhiambure>
Submitted:  Sat 14 May 2016 06:20:13 AM UTC
   
 
Category:  IPv6 Severity:  3 - Normal
Item Group:  Faulty Behaviour Status:  Fixed
Privacy:  Public Assigned to:  goldsimon
Open/Closed:  Closed Planned Release:  None
lwIP version:  1.4.1

Jump to the original submission

Mon 19 Sep 2016 01:36:00 AM UTC, comment #8: 

The attached patch fixes the problem by evaluating prefix_length, not the option length. I now get a routable address again.

Daniel Elstner <danielk>
Mon 19 Sep 2016 01:22:23 AM UTC, comment #7: 

Well, according to RFC4861 the length field is actually constant and always 4. So the patch for this bug is clearly invalid.

https://tools.ietf.org/html/rfc4861#section-4.6.2

Daniel Elstner <danielk>
Mon 19 Sep 2016 01:15:10 AM UTC, comment #6: 

This change broke stateless autoconfiguration in my network.

I upgraded from STABLE_2_0_0 to master and now my device no longer gets a routable IP assigned, in addition to the link-local address. With the commit for this bug reverted, it works again.

The IP I get from the router is:
2A02:8109:8100:24:804:68FF:FE8B:1148

I added some debug printouts and it turns out that prefix_opt->length is 4, not 64. No idea if there is anything invalid about it. The link-local test returns false.

Daniel Elstner <danielk>
Thu 25 Aug 2016 12:20:56 PM UTC, comment #5: 

fixed, thanks for the patch.

Simon Goldschmidt <goldsimon>
Group administrator
Tue 24 May 2016 06:10:50 AM UTC, comment #4: 

according to rfc 4862 :- section 5.5.3 :- If the sum of the prefix length and interface identifier length does not equal 128 bits, the Prefix Information option MUST be ignored.

So we have interface identifiers as 64 bit(EUI-64) hence prefix length must be 64 bits only.

(file #37246)

abhishek ambure <abhiambure>
Tue 24 May 2016 05:45:18 AM UTC, comment #3: 

if we process such link local prefix in Router advertisement for stateless address auto configuration then we will be having 2 or more link local address for that interface. It will consume useless entries in the netif address list.

abhishek ambure <abhiambure>
Tue 24 May 2016 05:37:12 AM UTC, comment #2: 

i have added file to this post, router advertisement message used for SLAAC must be silently discarded if the in prefix options is containing link local prefix. Whenever we get such Router advertisement, we should not process it for SLAAC and must bit another link-local ipv6 address in existing address.

(file #37245)

abhishek ambure <abhiambure>
Mon 23 May 2016 08:43:19 PM UTC, comment #1: 

I'd be very happy if you could provide a patch to show what you mean :-)

Simon Goldschmidt <goldsimon>
Group administrator
Sat 14 May 2016 06:20:13 AM UTC, original submission:  

according to RFC 4862 , section 5.5.3 link-local prefix in RA message must be silently discarded. And prefix length has to 64 if interface id is EUI64. So need to validate prefix length too.

abhishek ambure <abhiambure>

 

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Attached Files
file #38545:  0001-bug-74921-check-prefix_length-not-length.patch added by danielk (854B - text/x-patch - Fix for the fix)

 

Depends on the following items: None found

Items that depend on this one: None found

 

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  • -email is unavailable- added by dziegel (Updated the item)
  • -email is unavailable- added by danielk (Posted a comment)
  • -email is unavailable- added by goldsimon (Posted a comment)
  • -email is unavailable- added by abhiambure (Submitted the item)
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    Follow 10 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2016-09-19 dziegel StatusIn Progress Fixed
        Open/ClosedOpen Closed
    2016-09-19 dziegel StatusFixed In Progress
        Open/ClosedClosed Open
    2016-09-19 danielk Attached File- Added 0001-bug-74921-check-prefix_length-not-length.patch, #38545
    2016-08-25 goldsimon StatusNone Fixed
        Assigned toNone goldsimon
        Open/ClosedOpen Closed
    2016-05-24 abhiambure Attached File- Added nd6_llprefix_slaac_patch.txt, #37246
    2016-05-24 abhiambure Attached File- Added nd6_llprefix_slaac_patch.txt, #37245

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