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Diffstat (limited to 'src/x509.erl')
| -rw-r--r-- | src/x509.erl | 514 |
1 files changed, 0 insertions, 514 deletions
diff --git a/src/x509.erl b/src/x509.erl deleted file mode 100644 index 279d9b9..0000000 --- a/src/x509.erl +++ /dev/null @@ -1,514 +0,0 @@ -%%% Copyright (c) 2014-2015, NORDUnet A/S. -%%% See LICENSE for licensing information. - --module(x509). --export([normalise_chain/2, cert_string/1, read_pemfiles_from_dir/1, - self_signed/1, detox/2]). --include_lib("public_key/include/public_key.hrl"). --include_lib("eunit/include/eunit.hrl"). --import(lists, [nth/2, filter/2]). - --type reason() :: {chain_too_long | - root_unknown | - signature_mismatch | - encoding_invalid}. - --define(MAX_CHAIN_LENGTH, 10). --define(LEAF_POISON_OID, {1,3,6,1,4,1,11129,2,4,3}). --define(LEAF_POISON_VAL, [5,0]). --define(CA_POISON_OID, {1,3,6,1,4,1,11129,2,4,4}). - --spec normalise_chain([binary()], [binary()]) -> {ok, [binary()]} | - {error, reason()}. -normalise_chain(AcceptableRootCerts, CertChain) -> - case normalise_chain(AcceptableRootCerts, CertChain, ?MAX_CHAIN_LENGTH) of - {false, Reason} -> - {error, Reason}; - {true, Root} -> - {ok, CertChain ++ Root} - end. - --spec cert_string(binary()) -> string(). -cert_string(Der) -> - mochihex:to_hex(crypto:hash(sha, Der)). - --spec read_pemfiles_from_dir(file:filename()) -> [binary()]. -%% @doc Reading certificates from files. Flattening the result -- all -%% certs in all files are returned in a single list. -read_pemfiles_from_dir(Dir) -> - case file:list_dir(Dir) of - {error, enoent} -> - lager:error("directory does not exist: ~p", [Dir]), - []; - {error, Reason} -> - lager:error("unable to read directory ~p: ~p", [Dir, Reason]), - []; - {ok, Filenames} -> - Files = lists:filter( - fun(F) -> string:equal(".pem", filename:extension(F)) end, - Filenames), - ders_from_pemfiles(Dir, Files) - end. - --spec self_signed([binary()]) -> [binary()]. -%% @doc Return a list of certs in L that are self signed. -self_signed(L) -> - lists:filter(fun(Cert) -> signed_by_p(Cert, Cert) end, L). - --spec detox(binary(), [binary()]) -> {binary(), binary()}. -%% @doc Return a detoxed LeafDer and its issuer. -detox(LeafDer, ChainDer) -> - detox_precert(LeafDer, nth(1, ChainDer), nth(2, ChainDer)). - -%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -%% Private functions. - --spec normalise_chain([binary()], [binary()], integer()) -> - {false, reason()} | {true, [binary()]}. -%% @doc Verify that the leaf cert or precert has a valid chain back to -%% an acceptable root cert. The order of certificates in the second -%% argument is: leaf cert in head, chain in tail. Order of first -%% argument is irrelevant. -%% -%% Return {false, Reason} or {true, ListWithRoot}. Note that -%% ListWithRoot allways contain exactly one element -- a CA cert from -%% first argument (AcceptableRootCerts) signing the root of the -%% chain. FIXME: Any point in returning this as a list? -normalise_chain(_, _, MaxChainLength) when MaxChainLength =< 0 -> - %% Chain too long. - {false, chain_too_long}; -normalise_chain(AcceptableRootCerts, [TopCert], MaxChainLength) -> - %% Check root of chain. - case lists:member(TopCert, AcceptableRootCerts) of - true -> - %% Top cert is part of chain. - {true, [TopCert]}; - false when MaxChainLength =< 1 -> - %% Chain too long. - {false, chain_too_long}; - false -> - %% Top cert _might_ be signed by a cert in truststore. - case signer(TopCert, AcceptableRootCerts) of - notfound -> {false, root_unknown}; - Root -> {true, [Root]} - end - end; -normalise_chain(AcceptableRootCerts, [BottomCert|Rest], MaxChainLength) -> - case signed_by_p(BottomCert, hd(Rest)) of - true -> normalise_chain(AcceptableRootCerts, Rest, MaxChainLength - 1); - false -> {false, signature_mismatch} - end. - --spec signer(binary(), [binary()]) -> notfound | binary(). -%% @doc Return first cert in list signing Cert, or notfound. NOTE: -%% This is potentially expensive. It'd be more efficient to search for -%% Cert.issuer in a list of Issuer.subject's. If so, maybe make the -%% matching somewhat fuzzy unless that too is expensive. -signer(_Cert, []) -> - notfound; -signer(Cert, [H|T]) -> - case signed_by_p(Cert, H) of - true -> - H; - false -> - signer(Cert, T) - end. - --spec encoded_tbs_cert(binary()) -> binary(). -%% Code from pubkey_cert:encoded_tbs_cert/1. -encoded_tbs_cert(DerCert) -> - {ok, PKIXCert} = - 'OTP-PUB-KEY':decode_TBSCert_exclusive(DerCert), - {'Certificate', {'Certificate_tbsCertificate', EncodedTBSCert}, _, _} = - PKIXCert, - EncodedTBSCert. - --spec decode_cert(binary()) -> #'Certificate'{} | error. -decode_cert(Der) -> - case (catch public_key:pkix_decode_cert(Der, plain)) of - #'Certificate'{} = Cert -> - Cert; - {'EXIT', Reason} -> - lager:info("invalid certificate: ~p: ~p", [cert_string(Der), Reason]), - dump_unparsable_cert(Der), - error; - Unknown -> - lager:info("unknown error decoding cert: ~p: ~p", - [cert_string(Der), Unknown]), - error - end. - -parsable_cert_p(Der) -> - case decode_cert(Der) of - error -> - false; - _ -> - true - end. - -%% @doc Is Cert signed by Issuer? Only verify that the signature -%% matches and don't check things like Cert.issuer == Issuer.subject. --spec signed_by_p(binary(), binary()) -> boolean(). -signed_by_p(SubjectDer, IssuerDer) -> - SubjectCert = decode_cert(SubjectDer), - IssuerCert = decode_cert(IssuerDer), - - case {SubjectCert, IssuerCert} of - {#'Certificate'{}, - #'Certificate'{tbsCertificate = - #'TBSCertificate'{subjectPublicKeyInfo = - IssuerSPKI}}} -> - %% Dig out digest, digest type and signature from subject cert and - %% verify signature. - case extract_verify_data(decode_cert(SubjectDer), SubjectDer) of - error -> - false; - {ok, SubjectData} -> - verify_sig(IssuerSPKI, SubjectData) - end; - _ -> - false - end. - -verify_sig(IssuerSPKI, {DigestOrPlainText, DigestType, Signature}) -> - %% Dig out alg, params and key from issuer. - #'SubjectPublicKeyInfo'{ - algorithm = #'AlgorithmIdentifier'{algorithm = Alg, parameters = Params}, - subjectPublicKey = {0, Key0}} = IssuerSPKI, - KeyType = pubkey_cert_records:supportedPublicKeyAlgorithms(Alg), - IssuerKey = - case KeyType of - 'RSAPublicKey' -> - public_key:der_decode(KeyType, Key0); - 'ECPoint' -> - Point = #'ECPoint'{point = Key0}, - ECParams = public_key:der_decode('EcpkParameters', Params), - {Point, ECParams}; - _ -> % FIXME: 'DSAPublicKey' - lager:error("NIY: Issuer key type ~p", [KeyType]), - false - end, - %% Verify the signature. - public_key:verify(DigestOrPlainText, DigestType, Signature, IssuerKey). - --spec extract_verify_data(#'Certificate'{}, binary()) -> {ok, tuple()} | error. -%% @doc Return DER encoded TBScertificate, digest type and signature. -%% Code from pubkey_cert:extract_verify_data/2. -extract_verify_data(Cert, DerCert) -> - PlainText = encoded_tbs_cert(DerCert), - {_, Sig} = Cert#'Certificate'.signature, - SigAlgRecord = Cert#'Certificate'.signatureAlgorithm, - SigAlg = SigAlgRecord#'AlgorithmIdentifier'.algorithm, - try - {DigestType, _} = public_key:pkix_sign_types(SigAlg), - {ok, {PlainText, DigestType, Sig}} - catch - error:function_clause -> - lager:debug("~p: signature algorithm not supported: ~p", - [cert_string(DerCert), SigAlg]), - error - end. - -%% Precerts according to RFC6962. -%% -%% Submitted precerts have a special critical poison extension -- OID -%% 1.3.6.1.4.1.11129.2.4.3, whose extnValue OCTET STRING contains -%% ASN.1 NULL data (0x05 0x00). -%% -%% They are signed with either the CA cert that will sign the final -%% cert or a Precertificate Signing Certificate directly signed by the -%% CA cert that will sign the final cert. A Precertificate Signing -%% Certificate has CA:true and Extended Key Usage: Certificate -%% Transparency, OID 1.3.6.1.4.1.11129.2.4.4. -%% -%% PreCert in SignedCertificateTimestamp does _not_ contain the poison -%% extension, nor does it have an issuer which is a Precertificate -%% Signing Certificate. This means that we have to 1) remove the -%% poison extension and 2) potentially change issuer and Authority Key -%% Identifier. See RFC6962 Section 3.2. -%% -%% Changes in draft-ietf-trans-rfc6962-bis-??: TODO. - --spec detox_precert(binary(), binary(), binary()) -> {binary(), binary()}. -%% @doc Return {DetoxedLeaf, IssuerPubKeyHash} where i) DetoxedLeaf is -%% the tbsCertificate w/o poison and adjusted issuer and authkeyid; -%% and ii) IssuerPubKeyHash is the hash over issuing cert's public -%% key. -detox_precert(LeafDer, ParentDer, GrandParentDer) -> - Leaf = public_key:pkix_decode_cert(LeafDer, plain), - Parent = public_key:pkix_decode_cert(ParentDer, plain), - GrandParent = public_key:pkix_decode_cert(GrandParentDer, plain), - DetoxedLeafTBS = remove_poison_ext(Leaf), - - %% If parent is a precert signing cert, change issuer and - %% potential authority key id to refer to grandparent. - {C, IssuerKeyHash} = - case is_precert_signer(Parent) of - true -> - {set_issuer_and_authkeyid(DetoxedLeafTBS, Parent), - extract_pub_key(GrandParent)}; - false -> - {DetoxedLeafTBS, extract_pub_key(Parent)} - end, - {public_key:pkix_encode('TBSCertificate', C, plain), - crypto:hash(sha256, public_key:pkix_encode( - 'SubjectPublicKeyInfo', IssuerKeyHash, plain))}. - --spec extract_pub_key(#'Certificate'{}) -> #'SubjectPublicKeyInfo'{}. -extract_pub_key(#'Certificate'{ - tbsCertificate = #'TBSCertificate'{ - subjectPublicKeyInfo = SPKI}}) -> - SPKI. - --spec set_issuer_and_authkeyid(#'TBSCertificate'{}, #'Certificate'{}) -> - #'TBSCertificate'{}. -%% @doc Return Cert with issuer and AuthorityKeyIdentifier from Parent. -set_issuer_and_authkeyid(TBSCert, - #'Certificate'{ - tbsCertificate = - #'TBSCertificate'{ - issuer = ParentIssuer, - extensions = ParentExtensions}}) -> - case pubkey_cert:select_extension(?'id-ce-authorityKeyIdentifier', - ParentExtensions) of - undefined -> - lager:debug("setting issuer only", []), - TBSCert#'TBSCertificate'{issuer = ParentIssuer}; - ParentAuthKeyExt -> - NewExtensions = - lists:map( - fun(E) -> - case E of - #'Extension'{extnID = - ?'id-ce-authorityKeyIdentifier'} -> - lager:debug("swapping auth key id to ~p", - [ParentAuthKeyExt]), - ParentAuthKeyExt; - _ -> E - end - end, - TBSCert#'TBSCertificate'.extensions), - lager:debug("setting issuer and auth key id", []), - TBSCert#'TBSCertificate'{issuer = ParentIssuer, - extensions = NewExtensions} - end. - --spec is_precert_signer(#'Certificate'{}) -> boolean(). -is_precert_signer(#'Certificate'{tbsCertificate = TBSCert}) -> - Extensions = pubkey_cert:extensions_list(TBSCert#'TBSCertificate'.extensions), - %% NOTE: It's OK to look at only the first extension found since - %% "A certificate MUST NOT include more than one instance of a - %% particular extension." --RFC5280 Sect 4.2 - case pubkey_cert:select_extension(?'id-ce-extKeyUsage', Extensions) of - #'Extension'{extnValue = Val} -> - case 'OTP-PUB-KEY':decode('ExtKeyUsageSyntax', Val) of - %% NOTE: We require that the poisoned OID is the - %% _only_ extkeyusage present. RFC6962 Sect 3.1 is not - %% really clear. - {ok, [?CA_POISON_OID]} -> is_ca(TBSCert); - _ -> false - end; - _ -> false - end. - --spec is_ca(#'TBSCertificate'{}) -> boolean(). -is_ca(#'TBSCertificate'{extensions = Extensions}) -> - case pubkey_cert:select_extension(?'id-ce-basicConstraints', Extensions) of - #'Extension'{critical = true, extnValue = Val} -> - case 'OTP-PUB-KEY':decode('BasicConstraints', Val) of - {ok, {'BasicConstraints', true, _}} -> true; - _ -> false - end; - _ -> false - end. - --spec remove_poison_ext(#'Certificate'{}) -> #'TBSCertificate'{}. -remove_poison_ext(#'Certificate'{tbsCertificate = TBSCert}) -> - Extensions = - filter(fun(E) -> not poisoned_leaf_p(E) end, - pubkey_cert:extensions_list(TBSCert#'TBSCertificate'.extensions)), - TBSCert#'TBSCertificate'{extensions = Extensions}. - --spec poisoned_leaf_p(binary()) -> boolean(). -poisoned_leaf_p(#'Extension'{extnID = ?LEAF_POISON_OID, - critical = true, - extnValue = ?LEAF_POISON_VAL}) -> - true; -poisoned_leaf_p(_) -> - false. - -%%%% PEM files. --spec ders_from_pemfiles(string(), [string()]) -> [binary()]. -ders_from_pemfiles(Dir, Filenames) -> - lists:flatten( - [ders_from_pemfile(filename:join(Dir, X)) || X <- Filenames]). - --spec ders_from_pemfile(string()) -> [binary()]. -ders_from_pemfile(Filename) -> - lager:debug("reading PEM from ~s", [Filename]), - PemBins = pems_from_file(Filename), - Pems = case (catch public_key:pem_decode(PemBins)) of - {'EXIT', Reason} -> - lager:info("~p: invalid PEM-encoding: ~p", [Filename, Reason]), - []; - P -> P - end, - [der_from_pem(X) || X <- Pems]. - --spec der_from_pem(binary()) -> binary(). -der_from_pem(Pem) -> - case Pem of - {_Type, Der, not_encrypted} -> - case parsable_cert_p(Der) of - true -> - Der; - false -> - dump_unparsable_cert(Der), - [] - end; - Fail -> - lager:info("ignoring PEM-encoded data: ~p~n", [Fail]), - [] - end. - --spec pems_from_file(file:filename()) -> binary(). -pems_from_file(Filename) -> - {ok, Pems} = file:read_file(Filename), - Pems. - --spec dump_unparsable_cert(binary()) -> ok | {error, atom()} | not_logged. -dump_unparsable_cert(Der) -> - case application:get_env(catlfish, rejected_certs_path) of - {ok, Directory} -> - {NowMegaSec, NowSec, NowMicroSec} = now(), - Filename = - filename:join(Directory, - io_lib:format("~p:~p.~p", - [cert_string(Der), - NowMegaSec * 1000 * 1000 + NowSec, - NowMicroSec])), - lager:info("dumping cert to ~p~n", [Filename]), - file:write_file(Filename, Der); - _ -> - not_logged - end. - -%%%%%%%%%%%%%%%%%%%% -%% Testing private functions. --include("x509_test.hrl"). -sign_test_() -> - {setup, - fun() -> ok end, - fun(_) -> ok end, - fun(_) -> [?_assertMatch(true, signed_by_p(?C0, ?C1))] end}. - -valid_cert_test_() -> - {setup, - fun() -> {read_pemfiles_from_dir("test/testdata/known_roots"), - read_certs("test/testdata/chains")} end, - fun(_) -> ok end, - fun({KnownRoots, Chains}) -> - [ - %% Self-signed but verified against itself so pass. - %% Note that this certificate is rejected by the - %% stricter OTP-PKIX.asn1 specification generating - %% #'OTPCertificate'{}. The error is - %% {invalid_choice_tag,{22,<<"US">>}}}} in - %% 'OTP-PUB-KEY':Func('OTP-X520countryname', Value0). - ?_assertMatch({true, _}, normalise_chain(nth(1, Chains), - nth(1, Chains), 10)), - %% Self-signed so fail. - ?_assertMatch({false, root_unknown}, - normalise_chain(KnownRoots, - nth(2, Chains), 10)), - %% Leaf signed by known CA, pass. - ?_assertMatch({true, _}, normalise_chain(KnownRoots, - nth(3, Chains), 10)), - %% Proper 3-depth chain with root in KnownRoots, pass. - %% Bug CATLFISH-19 --> [info] rejecting "3ee62cb678014c14d22ebf96f44cc899adea72f1": chain_broken - %% leaf sha1: 3ee62cb678014c14d22ebf96f44cc899adea72f1 - %% leaf Subject: C=KR, O=Government of Korea, OU=Group of Server, OU=\xEA\xB5\x90\xEC\x9C\xA1\xEA\xB3\xBC\xED\x95\x99\xEA\xB8\xB0\xEC\x88\xA0\xEB\xB6\x80, CN=www.berea.ac.kr, CN=haksa.bits.ac.kr - ?_assertMatch({true, _}, normalise_chain(KnownRoots, - nth(4, Chains), 3)), - %% Verify against self, pass. - %% Bug CATLFISH-??, can't handle issuer keytype ECPoint. - %% Issuer sha1: 6969562e4080f424a1e7199f14baf3ee58ab6abb - ?_assertMatch(true, signed_by_p(hd(nth(5, Chains)), - hd(nth(5, Chains)))), - %% Unsupported signature algorithm MD2-RSA, fail. - %% Signature Algorithm: md2WithRSAEncryption - %% CA cert with sha1 96974cd6b663a7184526b1d648ad815cf51e801a - ?_assertMatch(false, signed_by_p(hd(nth(6, Chains)), - hd(nth(6, Chains)))), - - %% Supposedly problematic chains from Google Aviator, fatal. - %% 00459972: asn1: syntax error: sequence truncated - ?_assertMatch({true, _}, normalise_chain(nth(7, Chains), - nth(7, Chains), 10)), - %% 1402673: x509: RSA modulus is not a positive number - ?_assertMatch({true, _}, normalise_chain(nth(8, Chains), - nth(8, Chains), 10)), - %% 1345105: asn1: syntax error: IA5String contains invalid character - ?_assertMatch({true, _}, normalise_chain(nth(9, Chains), - nth(9, Chains), 10)), - %% 1557693: asn1: structure error: integer too large - ?_assertMatch({true, _}, normalise_chain(nth(10, Chains), - nth(10, Chains), 10)), - - %% Supposedly problematic chains from Google Aviator, non-fatal. - %% 16800: x509: negative serial number - %% a.pem - ?_assertMatch({true, _}, normalise_chain(nth(11, Chains), - nth(11, Chains), 10)), - %% 22487: x509: unhandled critical extension ([2 5 29 32]) - %% b.pem - ?_assertMatch({true, _}, normalise_chain(nth(12, Chains), - nth(12, Chains), 10)), - %% 5198: x509: certificate contained IP address of length 8 - %% c.pem - ?_assertMatch({true, _}, normalise_chain(nth(13, Chains), - nth(13, Chains), 10)) - ] end}. - -chain_test_() -> - {setup, - fun() -> {?C0, ?C1} end, - fun(_) -> ok end, - fun({C0, C1}) -> chain_test(C0, C1) end}. - -chain_test(C0, C1) -> - [ - %% Root not in chain but in trust store. - ?_assertEqual({true, [C1]}, normalise_chain([C1], [C0], 10)), - ?_assertEqual({true, [C1]}, normalise_chain([C1], [C0], 2)), - %% Chain too long. - ?_assertMatch({false, chain_too_long}, normalise_chain([C1], [C0], 1)), - %% Root in chain and in trust store. - ?_assertEqual({true, [C1]}, normalise_chain([C1], [C0, C1], 2)), - %% Chain too long. - ?_assertMatch({false, chain_too_long}, normalise_chain([C1], [C0, C1], 1)), - %% Root not in trust store. - ?_assertMatch({false, root_unknown}, normalise_chain([], [C0, C1], 10)), - %% Selfsigned. Actually OK. - ?_assertMatch({true, [C0]}, normalise_chain([C0], [C0], 10)), - ?_assertMatch({true, [C0]}, normalise_chain([C0], [C0], 1)), - %% Max chain length 0 is not OK. - ?_assertMatch({false, chain_too_long}, normalise_chain([C0], [C0], 0)) - ]. - -%%-spec read_certs(file:filename()) -> [string:string()]. --spec read_certs(file:filename()) -> [[binary()]]. -read_certs(Dir) -> - {ok, Fnames} = file:list_dir(Dir), - PemBins = - [Pems || {ok, Pems} <- - [file:read_file(filename:join(Dir, F)) || - F <- lists:sort( - lists:filter( - fun(FN) -> string:equal( - ".pem", filename:extension(FN)) - end, - Fnames))]], - PemEntries = [public_key:pem_decode(P) || P <- PemBins], - lists:map(fun(L) -> [Der || {'Certificate', Der, not_encrypted} <- L] end, - PemEntries). |