From b219dbd698c74cf3c904445d13bb3453be6e1ac8 Mon Sep 17 00:00:00 2001 From: Magnus Henoch Date: Tue, 8 Dec 2015 18:23:42 +0000 Subject: Add ssl_crl_hash_dir module This module is an implementation of the ssl_crl_cache_api behaviour. It can be used when there is a directory containing CRLs for all relevant CAs, in the form used by e.g. Apache. The module assumes that the directory is being updated through an external process. --- lib/ssl/doc/src/ssl.xml | 60 ++++++++++-- lib/ssl/src/Makefile | 1 + lib/ssl/src/ssl.app.src | 1 + lib/ssl/src/ssl_crl_hash_dir.erl | 106 +++++++++++++++++++++ lib/ssl/test/make_certs.erl | 6 +- lib/ssl/test/ssl_crl_SUITE.erl | 201 ++++++++++++++++++++++++++++++++++++--- 6 files changed, 355 insertions(+), 20 deletions(-) create mode 100644 lib/ssl/src/ssl_crl_hash_dir.erl diff --git a/lib/ssl/doc/src/ssl.xml b/lib/ssl/doc/src/ssl.xml index a1fba5fbff..31f88f3285 100644 --- a/lib/ssl/doc/src/ssl.xml +++ b/lib/ssl/doc/src/ssl.xml @@ -360,15 +360,59 @@ marker="public_key:public_key#pkix_path_validation-3">public_key:pkix_path_valid

Specify how to perform lookup and caching of certificate revocation lists. Module defaults to ssl_crl_cache with DbHandle being internal and an - empty argument list. The following arguments may be specified for the internal cache:

+ empty argument list.

+ +

There are two implementations available:

+ - {http, timeout()} -

- Enables fetching of CRLs specified as http URIs in X509 certificate extensions. - Requires the OTP inets application.

- - + ssl_crl_cache + +

This module maintains a cache of CRLs. CRLs can be + added to the cache using the function ssl_crl_cache:insert/1, + and optionally automatically fetched through HTTP if the + following argument is specified:

+ + + {http, timeout()} +

+ Enables fetching of CRLs specified as http URIs inX509 certificate extensions. + Requires the OTP inets application.

+ + + + + ssl_crl_hash_dir + +

This module makes use of a directory where CRLs are + stored in files named by the hash of the issuer name.

+ +

The file names consist of eight hexadecimal digits + followed by .rN, where N is an integer, + e.g. 1a2b3c4d.r0. For the first version of the + CRL, N starts at zero, and for each new version, + N is incremented by one. The OpenSSL utility + c_rehash creates symlinks according to this + pattern.

+ +

For a given hash value, this module finds all + consecutive .r* files starting from zero, and those + files taken together make up the revocation list. CRL + files whose nextUpdate fields are in the past, or + that are issued by a different CA that happens to have the + same name hash, are excluded.

+ +

The following argument is required:

+ + + {dir, string()} +

Specifies the directory in which the CRLs can be found.

 + + + + + {partial_chain, fun(Chain::[DerCert]) -> {trusted_ca, DerCert} | diff --git a/lib/ssl/src/Makefile b/lib/ssl/src/Makefile index 7a7a373487..b625db0656 100644 --- a/lib/ssl/src/Makefile +++ b/lib/ssl/src/Makefile @@ -70,6 +70,7 @@ MODULES= \ ssl_session_cache \ ssl_crl\ ssl_crl_cache \ + ssl_crl_hash_dir \ ssl_socket \ ssl_listen_tracker_sup \ tls_record \ diff --git a/lib/ssl/src/ssl.app.src b/lib/ssl/src/ssl.app.src index 1a2bf90ccf..5aa399201a 100644 --- a/lib/ssl/src/ssl.app.src +++ b/lib/ssl/src/ssl.app.src @@ -44,6 +44,7 @@ ssl_crl, ssl_crl_cache, ssl_crl_cache_api, + ssl_crl_hash_dir, %% App structure ssl_app, ssl_sup, diff --git a/lib/ssl/src/ssl_crl_hash_dir.erl b/lib/ssl/src/ssl_crl_hash_dir.erl new file mode 100644 index 0000000000..bb62737232 --- /dev/null +++ b/lib/ssl/src/ssl_crl_hash_dir.erl @@ -0,0 +1,106 @@ +%% +%% %CopyrightBegin% +%% +%% Copyright Ericsson AB 2016-2016. All Rights Reserved. +%% +%% Licensed under the Apache License, Version 2.0 (the "License"); +%% you may not use this file except in compliance with the License. +%% You may obtain a copy of the License at +%% +%% http://www.apache.org/licenses/LICENSE-2.0 +%% +%% Unless required by applicable law or agreed to in writing, software +%% distributed under the License is distributed on an "AS IS" BASIS, +%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +%% See the License for the specific language governing permissions and +%% limitations under the License. +%% +%% %CopyrightEnd% + +-module(ssl_crl_hash_dir). + +-include_lib("public_key/include/public_key.hrl"). + +-behaviour(ssl_crl_cache_api). + +-export([lookup/3, select/2, fresh_crl/2]). + +lookup(#'DistributionPoint'{cRLIssuer = CRLIssuer} = DP, CertIssuer, CRLDbInfo) -> + Issuer = + case CRLIssuer of + asn1_NOVALUE -> + %% If the distribution point extension doesn't + %% indicate a CRL issuer, use the certificate issuer. + CertIssuer; + _ -> + CRLIssuer + end, + %% Find all CRLs for this issuer, and return those that match the + %% given distribution point. + AllCRLs = select(Issuer, CRLDbInfo), + lists:filter(fun(DER) -> + public_key:pkix_match_dist_point(DER, DP) + end, AllCRLs). + +fresh_crl(#'DistributionPoint'{}, CurrentCRL) -> + CurrentCRL. + +select(Issuer, {_DbHandle, [{dir, Dir}]}) -> + case find_crls(Issuer, Dir) of + [_|_] = DERs -> + DERs; + [] -> + %% That's okay, just report that we didn't find any CRL. + %% If the crl_check setting is best_effort, ssl_handshake + %% is happy with that, but if it's true, this is an error. + []; + {error, Error} -> + error_logger:error_report( + [{cannot_find_crl, Error}, + {dir, Dir}, + {module, ?MODULE}, + {line, ?LINE}]), + [] + end. + +find_crls(Issuer, Dir) -> + case filelib:is_dir(Dir) of + true -> + Hash = public_key:short_name_hash(Issuer), + find_crls(Issuer, Hash, Dir, 0, []); + false -> + {error, not_a_directory} + end. + +find_crls(Issuer, Hash, Dir, N, Acc) -> + Filename = filename:join(Dir, Hash ++ ".r" ++ integer_to_list(N)), + case file:read_file(Filename) of + {error, enoent} -> + Acc; + {ok, Bin} -> + try maybe_parse_pem(Bin) of + DER when is_binary(DER) -> + %% Found one file. Let's see if there are more. + find_crls(Issuer, Hash, Dir, N + 1, [DER] ++ Acc) + catch + error:Error -> + %% Something is wrong with the file. Report + %% it, and try the next one. + error_logger:error_report( + [{crl_parse_error, Error}, + {filename, Filename}, + {module, ?MODULE}, + {line, ?LINE}]), + find_crls(Issuer, Hash, Dir, N + 1, Acc) + end + end. + +maybe_parse_pem(<<"-----BEGIN", _/binary>> = PEM) -> + %% It's a PEM encoded file. Need to extract the DER + %% encoded data. + [{'CertificateList', DER, not_encrypted}] = public_key:pem_decode(PEM), + DER; +maybe_parse_pem(DER) when is_binary(DER) -> + %% Let's assume it's DER-encoded. + DER. + diff --git a/lib/ssl/test/make_certs.erl b/lib/ssl/test/make_certs.erl index 5eebf773a7..ed1a6523ed 100644 --- a/lib/ssl/test/make_certs.erl +++ b/lib/ssl/test/make_certs.erl @@ -172,11 +172,15 @@ revoke(Root, CA, User, C) -> gencrl(Root, CA, C). gencrl(Root, CA, C) -> + %% By default, the CRL is valid for 24 hours from now. + gencrl(Root, CA, C, 24). + +gencrl(Root, CA, C, CrlHours) -> CACnfFile = filename:join([Root, CA, "ca.cnf"]), CACRLFile = filename:join([Root, CA, "crl.pem"]), Cmd = [C#config.openssl_cmd, " ca" " -gencrl ", - " -crlhours 24", + " -crlhours ", integer_to_list(CrlHours), " -out ", CACRLFile, " -config ", CACnfFile], Env = [{"ROOTDIR", filename:absname(Root)}], diff --git a/lib/ssl/test/ssl_crl_SUITE.erl b/lib/ssl/test/ssl_crl_SUITE.erl index 5b86027210..27005682e9 100644 --- a/lib/ssl/test/ssl_crl_SUITE.erl +++ b/lib/ssl/test/ssl_crl_SUITE.erl @@ -41,20 +41,26 @@ groups() -> [ {check_true, [], [{group, v2_crl}, {group, v1_crl}, - {group, idp_crl}]}, + {group, idp_crl}, + {group, crl_hash_dir}]}, {check_peer, [], [{group, v2_crl}, {group, v1_crl}, - {group, idp_crl}]}, + {group, idp_crl}, + {group, crl_hash_dir}]}, {check_best_effort, [], [{group, v2_crl}, {group, v1_crl}, - {group, idp_crl}]}, + {group, idp_crl}, + {group, crl_hash_dir}]}, {v2_crl, [], basic_tests()}, {v1_crl, [], basic_tests()}, - {idp_crl, [], basic_tests()}]. + {idp_crl, [], basic_tests()}, + {crl_hash_dir, [], basic_tests() ++ crl_hash_dir_tests()}]. basic_tests() -> [crl_verify_valid, crl_verify_revoked, crl_verify_no_crl]. +crl_hash_dir_tests() -> + [crl_hash_dir_collision, crl_hash_dir_expired]. init_per_suite(Config) -> case os:find_executable("openssl") of @@ -101,7 +107,24 @@ init_per_group(Group, Config0) -> CertDir = filename:join(?config(priv_dir, Config0), Group), {CertOpts, Config} = init_certs(CertDir, Group, Config0), {ok, _} = make_certs:all(DataDir, CertDir, CertOpts), - [{cert_dir, CertDir}, {idp_crl, false} | Config] + case Group of + crl_hash_dir -> + CrlDir = filename:join(CertDir, "crls"), + %% Copy CRLs to their hashed filenames. + %% Find the hashes with 'openssl crl -noout -hash -in crl.pem'. + populate_crl_hash_dir(CertDir, CrlDir, + [{"erlangCA", "d6134ed3"}, + {"otpCA", "d4c8d7e5"}], + replace), + CrlCacheOpts = [{crl_cache, + {ssl_crl_hash_dir, + {internal, [{dir, CrlDir}]}}}]; + _ -> + CrlCacheOpts = [] + end, + [{crl_cache_opts, CrlCacheOpts}, + {cert_dir, CertDir}, + {idp_crl, false} | Config] end. end_per_group(_GroupName, Config) -> @@ -164,9 +187,10 @@ crl_verify_valid(Config) when is_list(Config) -> {crl_cache, {ssl_crl_cache, {internal, [{http, 5000}]}}}, {verify, verify_peer}]; false -> - [{cacertfile, filename:join([PrivDir, "server", "cacerts.pem"])}, - {crl_check, Check}, - {verify, verify_peer}] + ?config(crl_cache_opts, Config) ++ + [{cacertfile, filename:join([PrivDir, "server", "cacerts.pem"])}, + {crl_check, Check}, + {verify, verify_peer}] end, {ClientNode, ServerNode, Hostname} = ssl_test_lib:run_where(Config), @@ -196,9 +220,10 @@ crl_verify_revoked(Config) when is_list(Config) -> {crl_check, Check}, {verify, verify_peer}]; false -> - [{cacertfile, filename:join([PrivDir, "revoked", "cacerts.pem"])}, - {crl_check, Check}, - {verify, verify_peer}] + ?config(crl_cache_opts, Config) ++ + [{cacertfile, filename:join([PrivDir, "revoked", "cacerts.pem"])}, + {crl_check, Check}, + {verify, verify_peer}] end, crl_verify_error(Hostname, ServerNode, ServerOpts, ClientNode, ClientOpts, @@ -251,6 +276,132 @@ crl_verify_no_crl(Config) when is_list(Config) -> crl_verify_valid(Hostname, ServerNode, ServerOpts, ClientNode, ClientOpts) end. +crl_hash_dir_collision() -> + [{doc,"Verify ssl_crl_hash_dir behaviour with hash collisions"}]. +crl_hash_dir_collision(Config) when is_list(Config) -> + PrivDir = ?config(cert_dir, Config), + Check = ?config(crl_check, Config), + + %% Create two CAs whose names hash to the same value + CA1 = "hash-collision-0000000000", + CA2 = "hash-collision-0258497583", + CertsConfig = make_certs:make_config([]), + make_certs:intermediateCA(PrivDir, CA1, "erlangCA", CertsConfig), + make_certs:intermediateCA(PrivDir, CA2, "erlangCA", CertsConfig), + + make_certs:enduser(PrivDir, CA1, "collision-client-1", CertsConfig), + make_certs:enduser(PrivDir, CA2, "collision-client-2", CertsConfig), + + [ServerOpts1, ServerOpts2] = + [ + [{keyfile, filename:join([PrivDir, EndUser, "key.pem"])}, + {certfile, filename:join([PrivDir, EndUser, "cert.pem"])}, + {cacertfile, filename:join([PrivDir, EndUser, "cacerts.pem"])}] + || EndUser <- ["collision-client-1", "collision-client-2"]], + + %% Add CRLs for our new CAs into the CRL hash directory. + %% Find the hashes with 'openssl crl -noout -hash -in crl.pem'. + CrlDir = filename:join(PrivDir, "crls"), + populate_crl_hash_dir(PrivDir, CrlDir, + [{CA1, "b68fc624"}, + {CA2, "b68fc624"}], + replace), + + ClientOpts = ?config(crl_cache_opts, Config) ++ + [{cacertfile, filename:join([PrivDir, "erlangCA", "cacerts.pem"])}, + {crl_check, Check}, + {verify, verify_peer}], + + {ClientNode, ServerNode, Hostname} = ssl_test_lib:run_where(Config), + + %% Neither certificate revoked; both succeed. + crl_verify_valid(Hostname, ServerNode, ServerOpts1, ClientNode, ClientOpts), + crl_verify_valid(Hostname, ServerNode, ServerOpts2, ClientNode, ClientOpts), + + make_certs:revoke(PrivDir, CA1, "collision-client-1", CertsConfig), + populate_crl_hash_dir(PrivDir, CrlDir, + [{CA1, "b68fc624"}, + {CA2, "b68fc624"}], + replace), + + %% First certificate revoked; first fails, second succeeds. + crl_verify_error(Hostname, ServerNode, ServerOpts1, ClientNode, ClientOpts, + "certificate revoked"), + crl_verify_valid(Hostname, ServerNode, ServerOpts2, ClientNode, ClientOpts), + + make_certs:revoke(PrivDir, CA2, "collision-client-2", CertsConfig), + populate_crl_hash_dir(PrivDir, CrlDir, + [{CA1, "b68fc624"}, + {CA2, "b68fc624"}], + replace), + + %% Second certificate revoked; both fail. + crl_verify_error(Hostname, ServerNode, ServerOpts1, ClientNode, ClientOpts, + "certificate revoked"), + crl_verify_error(Hostname, ServerNode, ServerOpts2, ClientNode, ClientOpts, + "certificate revoked"), + + ok. + +crl_hash_dir_expired() -> + [{doc,"Verify ssl_crl_hash_dir behaviour with expired CRLs"}]. +crl_hash_dir_expired(Config) when is_list(Config) -> + PrivDir = ?config(cert_dir, Config), + Check = ?config(crl_check, Config), + + CA = "CRL-maybe-expired-CA", + %% Add "issuing distribution point", to ensure that verification + %% fails if there is no valid CRL. + CertsConfig = make_certs:make_config([{issuing_distribution_point, true}]), + make_certs:intermediateCA(PrivDir, CA, "erlangCA", CertsConfig), + EndUser = "CRL-maybe-expired", + make_certs:enduser(PrivDir, CA, EndUser, CertsConfig), + + ServerOpts = [{keyfile, filename:join([PrivDir, EndUser, "key.pem"])}, + {certfile, filename:join([PrivDir, EndUser, "cert.pem"])}, + {cacertfile, filename:join([PrivDir, EndUser, "cacerts.pem"])}], + ClientOpts = ?config(crl_cache_opts, Config) ++ + [{cacertfile, filename:join([PrivDir, CA, "cacerts.pem"])}, + {crl_check, Check}, + {verify, verify_peer}], + {ClientNode, ServerNode, Hostname} = ssl_test_lib:run_where(Config), + + %% First make a CRL that expired yesterday. + make_certs:gencrl(PrivDir, CA, CertsConfig, -24), + CrlDir = filename:join(PrivDir, "crls"), + populate_crl_hash_dir(PrivDir, CrlDir, + [{CA, "1627b4b0"}], + replace), + + %% Since the CRL has expired, it's treated as missing, and the + %% outcome depends on the crl_check setting. + case Check of + true -> + %% The error "revocation status undetermined" gets turned + %% into "bad certificate". + crl_verify_error(Hostname, ServerNode, ServerOpts, ClientNode, ClientOpts, + "bad certificate"); + peer -> + crl_verify_error(Hostname, ServerNode, ServerOpts, ClientNode, ClientOpts, + "bad certificate"); + best_effort -> + %% In "best effort" mode, we consider the certificate not + %% to be revoked if we can't find the appropriate CRL. + crl_verify_valid(Hostname, ServerNode, ServerOpts, ClientNode, ClientOpts) + end, + + %% Now make a CRL that expires tomorrow. + make_certs:gencrl(PrivDir, CA, CertsConfig, 24), + CrlDir = filename:join(PrivDir, "crls"), + populate_crl_hash_dir(PrivDir, CrlDir, + [{CA, "1627b4b0"}], + add), + + %% With a valid CRL, verification should always pass. + crl_verify_valid(Hostname, ServerNode, ServerOpts, ClientNode, ClientOpts), + + ok. + crl_verify_valid(Hostname, ServerNode, ServerOpts, ClientNode, ClientOpts) -> Server = ssl_test_lib:start_server([{node, ServerNode}, {port, 0}, {from, self()}, @@ -311,3 +462,31 @@ make_dir_path(PathComponents) -> rename_crl(Filename) -> file:rename(Filename, Filename ++ ".notfound"). + +populate_crl_hash_dir(CertDir, CrlDir, CAsHashes, AddOrReplace) -> + ok = filelib:ensure_dir(filename:join(CrlDir, "crls")), + case AddOrReplace of + replace -> + %% Delete existing files, so we can override them. + [ok = file:delete(FileToDelete) || + {_CA, Hash} <- CAsHashes, + FileToDelete <- filelib:wildcard( + filename:join(CrlDir, Hash ++ ".r*"))]; + add -> + ok + end, + %% Create new files, incrementing suffix if needed to find unique names. + [{ok, _} = + file:copy(filename:join([CertDir, CA, "crl.pem"]), + find_free_name(CrlDir, Hash, 0)) + || {CA, Hash} <- CAsHashes], + ok. + +find_free_name(CrlDir, Hash, N) -> + Name = filename:join(CrlDir, Hash ++ ".r" ++ integer_to_list(N)), + case filelib:is_file(Name) of + true -> + find_free_name(CrlDir, Hash, N + 1); + false -> + Name + end. -- cgit v1.2.3