sra/rpki.net - Dragon Research Labs RPKI Toolkit

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author	Rob Austein <sra@hactrn.net>	2007-08-06 15:22:28 +0000
committer	Rob Austein <sra@hactrn.net>	2007-08-06 15:22:28 +0000
commit	8becf9cf697252d70b65550ec45f9cc347c80c3d (patch)
tree	dd674ca0a06f0dbc0bd0060415bfe2f17df0462f /scripts/rpki/left_right.py
parent	0cdbc4a3263eaa1c83fd500bad4618e3fd9790ed (diff)

Checkpoint

svn path=/scripts/irbe-cli.py; revision=825

Diffstat (limited to 'scripts/rpki/left_right.py')

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$Id$ -*- Text -*- OpenSSL hacked to add support for the RFC 3779 X.509 v3 extensions. There are two ways to build this: - Apply patch-rpki-openssl-0.9.8 against a stock OpenSSL 0.9.8 distribution, eg, drop this patch into /usr/ports/security/openssl/files-beta/ on a FreeBSD machine. - Build the code in trunk/. You will need to enable the RFC 3779 extensions in order for this to do anything interesting. If you just want to run it, do: ./config enable-rfc3779 If you think you might need debugging, you'd be better off with: ./Configure debug-sra enable-rfc3779 This is what the current openssl.conf syntax looks like for the RFC 3779 certificate extensions. Syntax is admittedly wretched, because it has to work with the existing OpenSSL code. Within that restriction, I've attempted to make this look as much as practical like the existing OpenSSL support for "multi-valued" extensions. RFC 3779 ASN.1 provided for easy reference. Notes: * Ranges are denoted with a hyphen, prefix lengths with a slash. * The "@" syntax indicating indirection through a separate section is part of the stock OpenSSL multi-valued extension support. * I didn't attempt to guess which addresses are IPv4 and which are IPv6 from the syntax, since the opensssl.conf multi-value syntax needs tags anyway. * SAFI support is present but minimal. If you want a SAFI, you have to specify its numeric value. It would be trivial to add additional keywords for specific SAFIs if there were a reason to do so. * The "sbgp-" names were already present in OpenSSL's table of known extension OIDs, so we just used them. ### # An address extension, all specified on one line sbgp-ipAddrBlock = critical, IPv4:10.1.1.1/32, IPv4:10.2.0.0-10.3.255.255 # An address extension, all specified on one line, with inheritance sbgp-ipAddrBlock = critical, IPv4:inherit, IPv6:2002::/16 # An address extension using SAFIs sbgp-ipAddrBlock = critical, IPv4-SAFI:1:10.1.1.1/32, IPv6-SAFI:1:2002::/16 # Address extension using an indirect section sbgp-ipAddrBlock = critical, @addr-section [addr-section] IPv4.0 = 10.0.0.1 IPv4.1 = 10.0.1.0/24 IPv4.2 = 10.2.0.0 - 10.3.255.255 IPv6.0 = 2002:1::/64 IPv6.1 = 2002:2:: - 2002:8::ffff:ffff:ffff:ffff:ffff ### # An ASID extension, all specified on one line: sbgp-autonomousSysNum = critical, AS:44, RDI:33-45 # ASID extension on one line using inheritance sbgp-autonomousSysNum = critical, AS:55, RDI:inherit # ASID extension using an indirect section sbgp-autonomousSysNum = critical, @asid-section [asid-section] AS.0 = 44 AS.1 = 55 - 77 RDI.0 = 33 Some notes on OpenSSL internals. O'Reilly "Network Security with OpenSSL" is a bit dated (four years old, corresponds roughly to OpenSSL 0.9.7), but still appears to be the closest thing there is to coherent documentation. Some updates and machine readable copies of examples are available at http://www.opensslbook.com/. In spite of its age, the book is useful as it gives a readable overview of bit and pieces of OpenSSL's internal programming environment which one would otherwise have to absorb from the code via osmosis. Chapter 10 is particularly useful, as are the sections on error handling and abstract I/O (the ERR and BIO packages, respectively) in chapter 4. OpenSSL's own doc is very patchy, although fairly extensive in places. Most of it eventually comes down to "Use the Source, Luke" with pointers on which bit of source serves as an interesting example. For x509v3 extentions, the place to start is doc/openssl.txt, which, oddly, turns out to be mostly about certificate extensions. It gives an overview of the mechanisms, in particular of the method routine interface for certificate extensions. For something like the RFC 3779 extensions, it's pretty clear that we need to use a "raw" extension (which, as far as I can tell, just means that the RFC 3779 stuff is complicated enough that the extension handler has to do a lot of work to deal with a complex ASN.1 structure that the rest of the code doesn't know much about). General note on global symbols in OpenSSL: always look at the header file for any global symbol you're using. In fact, it's probably best to do a global search (m-x tags-search if you're an emacs user) for all instances of a global symbol before attempting to use it, as there are a lot of things that one just has to know about how all the global stuff hangs together. There are header files full of magic definitions that one just has to one need to be extended. There are magic pre-sorted lists of handlers that one just needs to know about. Little or none of this is documented. Use the Source, Luke. In some cases -portions- of files are automatically generated by Perl scripts (eg, the per-type stack definitions in safestack.h). Ouch. If you see a large block of very repetitive stuff, check for comments indicating that it's automatically generated. Oh, and the indentation style is demented. Header files you definitely need to read if you're going to touch this stuff: crypto/x509v3/x509v3.h crypto/x509v3/ext_dat.h crypto/stack/safestack.h crypto/asn1/asn1t.h crypto/asn1/asn1.h crypto/objects/objects.h Automatically generated header files you'll need to skim, then go read the input files listed in the header comments and perhaps the generating Perl code: crypto/objects/obj_mac.h crypto/objects/obj_dat.h Much of the code shows a heavy Perl influence, presumably dating back clear to Eric Young. Some of the internal data structure operators have names that only make sense to a Perl programmer. Stacks are really lists, and may be sorted. Where code is automatically generated, it's done by Perl scripts. The configuration language for the whole package is a Perl script. Assembly code is all wrapped up inside perl scripts in a moderately clever attempt at being able to write the assembly language only once and use it with various assemblers with nontrivially different syntax. Much of the documentation markup (including manual pages) for the C code is .pod. I have not yet figured out where to hook in the extra goop that RFC 3779 will need for verification. Making extensions critical is easy enough, but the validation stuff in RFC 3779 2.3 and 3.3 needs to go somewhere. A lot of the missing documentation is buried in ssleay.txt, which the other documentation says not to read because it's so old. But it's where Eric explains all the basic data structures and expected usage as of the dawn of time, so most of the stuff that's so old that it's undocumented is really documented there. xxx_new() functions set pointers of sub-structures to NULL or allocate the substructures (one can leak memory if one doesn't know or check which a particular xxx_new() function has done...), and the xxx_free() functions clean up complex structures. So be sure to set unused pointers to NULL if one has been fiddling. Make sure that memory leak detection (CRYPTO_MDEBUG) is turned on when debugging. "make update" in the top level runs all the magic perl code that grovels through the code generating error codes, safestacks, etc. util/mkstack.pl finds DECLARE_STACK_OF() declarations and generates safestack definitions automatically if you run "make update". Be afraid. Be very very afraid. My initial test configuration was: ./Configure debug -DDEBUG_SAFESTACK which tried to pull in -lefence (/usr/ports/devel/ElectricFence), so I installed that. Sadly, ElectricFence is not kidding when it says it is very very very slow, but it was the bignum debugging printouts that were driving me nuts, so I ended up creating my own "debug-sra" configuration for the options I want. Random reminders and notes to myself: - The new stuff in crypto/x509v3/x509v3.h is not organized properly yet, it's all lumped in one place rather than being interleved with the other supported extensions. This was to make it easier for me to debug, but will proably need to be cleaned up eventually. - The reference for RDIs in RFC 3779 is incorrect. I've been told that the authoritative definition of RDIs is ISO 10747, available as http://www.acm.org/sigs/sigcomm/standards/iso_stds/IDRP/10747.TXT. - OpenSSL already checks for duplicate extensions: more precisely, unless we explicitly tell X509_get_ext_d2i() that we allow multiple extensions (by providing the idx parameter), it returns NULL if it finds duplicates. If we really want to check for presence of exactly one extension of a particular type, we call this function twice with the idx parameter and make sure that the second call returns NULL. - May need to check AKID in crypto/x509/x509_vfy.c:get_crl(). - Request extensions: see X509_REQ_get_extensions(), X509_REQ_add_extensions(), and copy_extensions(). The June meeting at APNIC came up with a list of desired OpenSSL primitives (transcribed by Geoff, thanks!). Current status, with notes and questions at the end. 1. Read a resource certificate and print nominated certificate field(s) (CLI command) or access data structure elements from the certificate (API) Status: Done CLI: openssl x509 -text API: i2r_ASIdentifiers(), i2r_IPAddrBlocks(), but in practice you'd rarely call these directly -- they're hooked into OpenSSL's X509V3_EXT_METHOD dispatch mechanism and cached by x509v3_cache_extensions(), so you'd call X509_get_ext_d2i() or just look for decoded data structures hanging off the X509 structure. 2. Verify a resource certificate (use the existing openssl interface which provides as inputs a) a set of 'trusted' certs and CRLs and b) a set of untrusted certs and CRLs and c) the cert to be verified. output is YES or NO and both a CLI and an API interface is desired Status: Done, for some definition of done (CLI program remains a crock, but I don't think I've made it worse than it already was). CLI: openssl verify API: Pre-existing X509_verify_cert() function now checks RFC 3779 path validation, which in turn checks for well formed extensions. 3. 3779_canonicalise - read in a data structure of a resource set and produce as output the 3779 canonical form of the resource set - the CLI interface will print this to stdout and the API interface will pass a ref to a data structure (or fill in a data struct or whatever makes sense!) Status: Done. CLI: openssl x509, openssl req, .... Called automatically as part of anything that reads RFC 3779 extensions from openssl.conf. API: v3_asid_canonize(), v3_addr_canonize(). 4. 3779_cmp reads in 2 x 3779_canonicalised data sets and outputs a comparison = EQUAL is the two are equal, or =SUBSET if data1 is a strict subset of data2, or = NOT in all other cases (CLI or API) (EQUAL, SUBSET, NOT) Status: API code written, not fully tested. No CLI. API functions test whether an extension uses inheritance, and whether one extension is a (possibly improper) subset of another. Subset test fails if either extension uses inheritance. API: v3_asid_inherits(), v3_addr_inherits(), v3_asid_subset(), v3_addr_subset(). 5. is_3379_canonical tests a single data set and returns CANONICAL if the resource is formatted according to 3779 or NOT is otherwise Status: Done. CLI: openssl verify calls this during path validation. No separate program to perform just this function, would not be hard to write one if it were needed. API: v3_asid_is_canonical(), v3_addr_is_canonical(). 6. is_in_cert takes a certificate and a resource set description and checks if the certificate 'covers' the resource set The outpouts are EQUAL if the resource cert precisely matches the resource set, SUBSET if the resource set is a subset of the certificate resource list, or NOT otherwise Status: Done. API: v3_asid_validate_resource_set(), v3_addr_validate_resource_set(). These return true if a certificate chain covers a resource set. "Resource sets" are represented as the C form of the appropriate extension, with the additional constraint that the resource set must not use inheritance; this constraint is enforced by the code (ie, using one of these functions on a resource set that specifies inheritance will always return false regardless of the contents of the chain). CLI: resource-set-test. Use the Source, Luke. 7. generate_resource_certificate generates a resource certificate - I'm not sure I understand what the inputs are to be here - perhaps a data structure of the fields and values, but this should be confirmed. the output is a DER object (or pem, or either selectable?) Status: Done, for some definition of done. CLI: openssl x509, openssl ca. API: Preexisting OpenSSL functions, augmented by method routines allowing OpenSSL to read and write RFC 3779 extensions. 8. generate a certificate request (previous note on which certificate request format to use is on the table) Status: Done, for some definition of done, for OpenSSL's native request format (PKCS10 DER, with or without Base64 "PEM" wrapper). CLI: openssl x509, openssl req. API: Preexisting OpenSSL functions, augmented by method routines allowing OpenSSL to read and write RFC 3779 extensions. 9. process a certificate request and say yes / no on whether the request is well formed. Status: Request processing within OpenSSL looks to be a mess, with entirely too much of it happening in applications rather than the library. Other API functions exist to test whether an extension is in canonical form, etcetera. Path validation can only be done in context of a particular certificate chain, which is probably out of scope for this primative. 10. process a certificate request and generate a certificate in response. Status: OpenSSL code is a mess, see (9). Generating certificate based on a certificate request is prexisting functionality; new code adds ability to process RFC 3779. If task here includes path validation with respect to signer's certificate chain, would require nontrivial changes to the OpenSSL CLI programs that sign requests, as none of them currently even look for certificate chains for the signer. API: Primitive #6 (above) extended to accept argument indicating whether inheritance is allowed, so that primitive #6 can be used to perform path validation on extensions pulled from a request. Notes: - "For some definition of done": opinions vary on whether the existing OpenSSL CLI tools are adaquate for the purposes for which people use them. For purposes of the above discussion, I'm assuming that they are, and that my task was just to teach the same tools to deal with the RFC 3779 extensions. - It turns out that the code I've written so far never needs to ask whether two extension data sets are equal, just whether one is a subset (possibly improper) of the other. Checking for equality is a somewhat different test, so rather than trying to combine the two, I might just provide separate functions that test for equality. I've pulled the stuff in trunk/ up to OpenSSL 0.9.8d so that people building against this will not be missing the security updates from the recent OpenSSL vulnerability firedrills. In theory nothing in the RPKI code was touched by this; the existing RPKI patch against 0.9.8b applies without changes against 0.9.8c and 0.9.8d. Please report any problems. The RFC 3997 patches were committed to the OpenSSL Project's CVS repository on 27 November 2006, on both HEAD and the OpenSSL_0_9_8-stable branch (thanks, Ben!). At the moment this code is only available from the OpenSSL project via CVS, but as it is now part of the OpenSSL source tree it should be present in future releases. At least for now, it's disabled by default, so you have to do "./config enable-rfc3779" to enable it.


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