On Sat, Sep 29, 2018 at 10:24 AM Joel M. Halpern <[email protected]> wrote:
> Like any other flag bits that are not assigned, this would be MBZ on > transmission, must be ignored on reception. Once assigned, > implementations that support the assignment would do whatever the > assigning document says. Very normal procedure. > OK, I haven't read the -mn- draft so I don't know if that will have a clean upgrade path. -Ekr > Yours, > Joel > > On 9/29/18 1:22 PM, Eric Rescorla wrote: > > > > > > On Sat, Sep 29, 2018 at 10:18 AM Joel M. Halpern <[email protected] > > <mailto:[email protected]>> wrote: > > > > With regard to the m-bit, I would prefer that this document leave the > > bit reserved, > > > > > > Just trying to think through the interop implications of this. Would it > > be must be zero and must ignore? something else? > > > > -Ekr > > > > and the LISP mobile node document assign the bit fromthe > > registry. That keeps a clean separation. > > > > Yours, > > Joel > > > > On 9/29/18 1:05 PM, Eric Rescorla wrote: > > > > > > > > > On Sat, Sep 29, 2018 at 9:30 AM Dino Farinacci > > <[email protected] <mailto:[email protected]> > > > <mailto:[email protected] <mailto:[email protected]>>> wrote: > > > > > > Thanks Eric for your great comments. Like I said in previous > > emails, > > > I’ll address the simple things here and then handle all the > > security > > > related stuff separately next week. > > > > > > I will do the same with Benjamin’s comments as well. And in > his > > > reply, send a diff with changes that reflect both Eric and > > > Benjamin’s comments. > > > > > > > On Sep 27, 2018, at 5:16 AM, Eric Rescorla <[email protected] > > <mailto:[email protected]> > > > <mailto:[email protected] <mailto:[email protected]>>> wrote: > > > > > > > > Rich version of this review at: > > > > https://mozphab-ietf.devsvcdev.mozaws.net/D4115 > > > > > > > > > > > > IMPORTANT > > > > S 5.2. > > > >> s: This is the SMR-invoked bit. This bit is set to 1 > > when > > > an xTR is > > > >> sending a Map-Request in response to a received > > SMR-based > > > Map- > > > >> Request. > > > >> > > > >> m: This is the LISP mobile-node m-bit. This bit is > > set by > > > xTRs that > > > >> operate as a mobile node as defined in > > [I-D.ietf-lisp-mn]. > > > > > > > > This would appear to create a normative reference to this > > > document. To > > > > avoid that, you need to specify how I behave if I receive > > it but I > > > > don't implement lisp-mn. > > > > > > I am find making it a normative reference but need the > > lisp-chairs > > > to comment. I am not sure what the implications of that are. > > > > > > > > > Me neither. Seems like it could go either way. My only interest > > is that > > > the protocol be unambiguous. > > > > > > > > > > > > > S 5.5. > > > >> is being mapped from a multicast destination EID. > > > >> > > > >> 5.5. EID-to-RLOC UDP Map-Reply Message > > > >> > > > >> A Map-Reply returns an EID-Prefix with a prefix > > length that > > > is less > > > >> than or equal to the EID being requested. The EID > being > > > requested is > > > > > > > > How do I behave if I receive an EID-Prefix that is less > > than any > > > of my > > > > mappings. So, I might have mappings for 10.1.0.0/16 > > <http://10.1.0.0/16> > > > <http://10.1.0.0/16> and 10.2.0.0/16 <http://10.2.0.0/16> > > <http://10.2.0.0/16> > > > > and someone asks me for 10.0.0.0/8 <http://10.0.0.0/8> > > <http://10.0.0.0/8>? > > > > > > > > > I think I'm still unclear on this point. > > > > > > Also, when you talk about prefix > > > > length, I assume you mean the length fo the mask? > > > > > > Yes, this is explained later in this section. Was that not > > helpful?? > > > > > > > > > I found it a bit confusing. It seems to me like there are two > > lengths > > > involved here: > > > > > > - The length of the field (4 or 16) > > > - The parts of the field that are significant (i.e., the mask) > > > > > > I had thought that "prefix length" referred to the former, but it > > seems > > > like here it > > > refers to the latter. > > > > > > > > > > S 5.6. > > > >> Authentication Data: This is the message digest used > > from > > > the output > > > >> of the MAC algorithm. The entire Map-Register > > payload is > > > >> authenticated with this field preset to 0. After > > the MAC is > > > >> computed, it is placed in this field. > > Implementations of > > > this > > > >> specification MUST include support for > HMAC-SHA-1-96 > > > [RFC2404], > > > >> and support for HMAC-SHA-256-128 [RFC4868] is > > RECOMMENDED. > > > > > > > > What prevents replay attacks here? I'm guessing it's the > > Map-Version- > > > > Number, but as I understand it, I can set this to 0. > > > > > > Well there are many. The nonce can change for each > Map-Register > > > sent. Same for Map-Version number as well as the key-id. > > > > > > > > > I think you need to describe the precise process of replay > > prevention here. > > > > > > > S 6.1. > > > >> receives an SMR-based Map-Request and the source is > > not in the > > > >> Locator-Set for the stored Map-Cache entry, then the > > > responding Map- > > > >> Request MUST be sent with an EID destination to the > > mapping > > > database > > > >> system. Since the mapping database system is a more > > secure > > > way to > > > >> reach an authoritative ETR, it will deliver the > > Map-Request > > > to the > > > >> authoritative source of the mapping data. > > > > > > > > If I'm understanding this correctly, this allows an ETR to > > prevent an > > > > ITR from learning that it is no longer the appropriate ETR > > for a > > > > prefix. The way this attack works is that before the > topology > > > shift, I > > > > send SMRs, thus causing Map-Requests, which, because my > > entry is > > > > cached, refresh the cache on the ITR past the topology > > shift. I can > > > > keep doing this indefinitely. Am I missing something > > > > > > Well if the ETR is being spoofed, then there is Map-Request > load, > > > but it won’t corrupt the ITR’s map-cache. The ITR always > sends a > > > verifying Map-Request to the mapping system to get the latest > and > > > authenticated RLOC-set for the mapping. Rate-limiting is > > necessary > > > so each SMR received DOES NOT result in a Map-Requerst to the > > > mapping system. > > > > > > > > > I'm probably just confused here: SMRs go through the mapping > > system, not > > > directly? If so, I agree that this wont' work. > > > > > > > > > > S 5. > > > >> \ | UDP Length | UDP > > Checksum > > > | > > > >> > > > > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > > >> | > > > | > > > >> | LISP Message > > > | > > > >> | > > > | > > > >> > > > > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > > > > > > > What do these two diagrams correspond to? v4 and v6? This > > needs > > > > explanation. > > > > > > It is th entire IP packet sent as a LISP control-message. The > > header > > > before the diagrams indicate they are UDP packets. > > > > > > > > > A caption would probably help. > > > > > > > S 5.2. > > > >> P: This is the probe-bit, which indicates that a > > Map-Request > > > SHOULD > > > >> be treated as a Locator reachability probe. The > > receiver > > > SHOULD > > > >> respond with a Map-Reply with the probe-bit set, > > > indicating that > > > >> the Map-Reply is a Locator reachability probe > > reply, with the > > > >> nonce copied from the Map-Request. See > RLOC-Probing > > > Section 7.1 > > > >> for more details. > > > > > > > > How am I supposed to handle this if I am a Map Server. > > > > > > It should be ignored. I will add text to reflect this point. > > Good point. > > > > > > > > > > > S 5.2. > > > >> receipt. > > > >> > > > >> L: This is the local-xtr bit. It is used by an xTR > in a > > > LISP site to > > > >> tell other xTRs in the same site that it is part > > of the > > > RLOC-set > > > >> for the LISP site. The L-bit is set to 1 when the > > RLOC > > > is the > > > >> sender's IP address. > > > > > > > > Is the xTR supposed to filter this on exiting the site. > > > > > > Nope. > > > > > > > > > Won't this cause problems on ingress to another site? > > > > > > > S 5.3. > > > >> originating Map-Request source. If the RLOC is not > > in the > > > Locator- > > > >> Set, then the ETR MUST send the "verifying > > Map-Request" to the > > > >> "piggybacked" EID. Doing this forces the "verifying > > > Map-Request" to > > > >> go through the mapping database system to reach the > > > authoritative > > > >> source of information about that EID, guarding against > > > RLOC-spoofing > > > >> in the "piggybacked" mapping data. > > > > > > > > This text here doesn't seem compatible with either of the > > two cases > > > > listed in "EID-prefix" above. > > > > > > I don’t understand the comment Eric. Maybe because I can’t > > find the > > > exact reference to EID-prefix where you think there is a > > conflict. > > > Please cite for me. Thanks. > > > > > > This does seem to have been assigned to the wrong text. > > > > > > I am referring to: > > > > > > " A Map-Reply returns an EID-Prefix with a prefix length that > > is less > > > than or equal to the EID being requested. The EID being > > requested is > > > either from the destination field of an IP header of a > > Data-Probe or > > > the EID record of a Map-Request. The RLOCs in the Map-Reply > are > > > " > > > > > > versus > > > > > > " EID-Prefix: This prefix is 4 octets for an IPv4 address > > family and > > > 16 octets for an IPv6 address family when the > > EID-Prefix-AFI is 1 > > > or 2, respectively. For other AFIs [AFI], the length > > varies and > > > for the LCAF AFI the format is defined in [RFC8060]. When > > a Map- > > > " > > > > > > This is just the question of whether "prefix length" refers to > > the field or > > > the significant bits of the field. > > > > > > > > > > > > > > > > > > > > S 5.4. > > > >> 'Nonce' field. > > > >> > > > >> Record TTL: This is the time in minutes the > recipient of > > > the Map- > > > >> Reply will store the mapping. If the TTL is 0, > > the entry > > > MUST be > > > >> removed from the cache immediately. If the value > is > > > 0xffffffff, > > > >> the recipient can decide locally how long to store > the > > > mapping. > > > > > > > > Am I supposed to merge this with previous mappings? REmove > > them? > > > > > > No replace it. There is text that says this that is not in the > > > packet format description section. > > > > > > > > > OK. > > > > > > > > > > S 8.3. > > > >> of the mapping database protocols. > > > >> > > > >> 8.3. Map-Server Processing > > > >> > > > >> Once a Map-Server has EID-Prefixes registered by its > > client > > > ETRs, it > > > >> can accept and process Map-Requests for them. > > > > > > > > This section is confusing because the introduction says > > that this > > > > function is only performed by Map-Resolvers: > > > > ' > > > > "The LISP Mapping Service defines two new types of > > LISP-speaking > > > > devices: the Map-Resolver, which accepts Map-Requests > > from an > > > > Ingress > > > > Tunnel Router (ITR) and "resolves" the EID-to-RLOC > > mapping using a > > > > mapping database; and the Map-Server, which learns > > authoritative > > > > EID- > > > > to-RLOC mappings from an Egress Tunnel Router (ETR) and > > publishes > > > > them in a database.” > > > > > > The document does cover the operation of a Map-Resolver and a > > > Map-Server. Some functions are performed only by > > Map-Resolvers only > > > and other different functions are performed by Map-Servers > only. > > > > > > I am not sure what you don’t understand. > > > > > > > > > Sure: As I understand it, Map Resolvers process Map Requests, and > > Map > > > Servers do not (that's what the quoted text seems to say). > > However, this > > > sentence talks about a Map Server processing a Map Request. > That's > > > where I am confused. > > > > > > -Ekr > > > > > > > > > Thanks, > > > Dino > > > > > >
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