From c7047421487c0e616b881c0922937bc759114233 Mon Sep 17 00:00:00 2001 From: Nathaniel McCallum Date: Fri, 3 May 2013 15:44:44 -0400 Subject: [PATCH 1/3] Check for keys in encrypted timestamp/challenge Encrypted timestamp and encrypted challenge cannot succeed if the client has no long-term key matching the request enctypes, so do not offer them in that case. ticket: 7630 NPM - This is a backport from the upstream fix. See upstream commits: https://github.com/krb5/krb5/commit/e50482720a805ecd8c160e4a8f4a846e6327dca2 https://github.com/krb5/krb5/commit/9593d1311fa5e6e841c429653ad35a63d17c2fdd --- src/kdc/kdc_preauth_ec.c | 23 +++++++++++++++++++++-- src/kdc/kdc_preauth_encts.c | 22 ++++++++++++++++++++-- 2 files changed, 41 insertions(+), 4 deletions(-) diff --git a/src/kdc/kdc_preauth_ec.c b/src/kdc/kdc_preauth_ec.c index 9d7236c..db3ad07 100644 --- a/src/kdc/kdc_preauth_ec.c +++ b/src/kdc/kdc_preauth_ec.c @@ -39,8 +39,27 @@ ec_edata(krb5_context context, krb5_kdc_req *request, krb5_kdcpreauth_moddata moddata, krb5_preauthtype pa_type, krb5_kdcpreauth_edata_respond_fn respond, void *arg) { - krb5_keyblock *armor_key = cb->fast_armor(context, rock); - (*respond)(arg, (armor_key == NULL) ? ENOENT : 0, NULL); + krb5_boolean have_client_keys = FALSE; + krb5_keyblock *armor_key; + krb5_key_data *kd; + int i; + + armor_key = cb->fast_armor(context, rock); + + for (i = 0; i < rock->request->nktypes; i++) { + if (krb5_dbe_find_enctype(context, rock->client, + rock->request->ktype[i], + -1, 0, &kd) == 0) { + have_client_keys = TRUE; + break; + } + } + + /* Encrypted challenge only works with FAST, and requires a client key. */ + if (armor_key == NULL || !have_client_keys) + (*respond)(arg, ENOENT, NULL); + else + (*respond)(arg, 0, NULL); } static void diff --git a/src/kdc/kdc_preauth_encts.c b/src/kdc/kdc_preauth_encts.c index d708061..adde6e2 100644 --- a/src/kdc/kdc_preauth_encts.c +++ b/src/kdc/kdc_preauth_encts.c @@ -34,9 +34,27 @@ enc_ts_get(krb5_context context, krb5_kdc_req *request, krb5_kdcpreauth_moddata moddata, krb5_preauthtype pa_type, krb5_kdcpreauth_edata_respond_fn respond, void *arg) { - krb5_keyblock *armor_key = cb->fast_armor(context, rock); + krb5_boolean have_client_keys = FALSE; + krb5_keyblock *armor_key; + krb5_key_data *kd; + int i; + + armor_key = cb->fast_armor(context, rock); + + for (i = 0; i < rock->request->nktypes; i++) { + if (krb5_dbe_find_enctype(context, rock->client, + rock->request->ktype[i], + -1, 0, &kd) == 0) { + have_client_keys = TRUE; + break; + } + } - (*respond)(arg, (armor_key != NULL) ? ENOENT : 0, NULL); + /* Encrypted timestamp must not be used with FAST, and requires a key. */ + if (armor_key != NULL || !have_client_keys) + (*respond)(arg, ENOENT, NULL); + else + (*respond)(arg, 0, NULL); } static void -- 1.8.2.1 From 4d19790527e2c9d52bb05abd6048a63a1a8c222c Mon Sep 17 00:00:00 2001 From: Greg Hudson Date: Mon, 29 Apr 2013 14:55:31 -0400 Subject: [PATCH 2/3] Don't send empty etype info from KDC RFC 4120 prohibits empty ETYPE-INFO2 sequences (though not ETYPE-INFO sequences), and our client errors out if it sees an empty sequence of either. ticket: 7630 --- src/kdc/kdc_preauth.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/src/kdc/kdc_preauth.c b/src/kdc/kdc_preauth.c index 42a37a8..5c3b615 100644 --- a/src/kdc/kdc_preauth.c +++ b/src/kdc/kdc_preauth.c @@ -1404,6 +1404,11 @@ etype_info_helper(krb5_context context, krb5_kdc_req *request, seen_des++; } } + + /* If the list is empty, don't send it at all. */ + if (i == 0) + goto cleanup; + if (etype_info2) retval = encode_krb5_etype_info2(entry, &scratch); else -- 1.8.2.1 From a04cf2e89f4101eb6c2ec44ef1948976fe5fe9d3 Mon Sep 17 00:00:00 2001 From: Greg Hudson Date: Thu, 2 May 2013 16:15:32 -0400 Subject: [PATCH 3/3] Make AS requests work with no client key If we cannot find a client key while preparing an AS reply, give preauth mechanisms a chance to replace the reply key before erroring out. ticket: 7630 --- src/kdc/do_as_req.c | 36 ++++++++++++++++++++---------------- src/kdc/kdc_preauth.c | 6 ++++++ 2 files changed, 26 insertions(+), 16 deletions(-) diff --git a/src/kdc/do_as_req.c b/src/kdc/do_as_req.c index 79da300..cb91803 100644 --- a/src/kdc/do_as_req.c +++ b/src/kdc/do_as_req.c @@ -195,23 +195,18 @@ finish_process_as_req(struct as_req_state *state, krb5_error_code errcode) useenctype, -1, 0, &client_key)) break; } - if (!(client_key)) { - /* Cannot find an appropriate key */ - state->status = "CANT_FIND_CLIENT_KEY"; - errcode = KRB5KDC_ERR_ETYPE_NOSUPP; - goto egress; - } - state->rock.client_key = client_key; - /* convert client.key_data into a real key */ - if ((errcode = krb5_dbe_decrypt_key_data(kdc_context, NULL, - client_key, - &state->client_keyblock, - NULL))) { - state->status = "DECRYPT_CLIENT_KEY"; - goto egress; + if (client_key != NULL) { + /* Decrypt the client key data entry to get the real reply key. */ + errcode = krb5_dbe_decrypt_key_data(kdc_context, NULL, client_key, + &state->client_keyblock, NULL); + if (errcode) { + state->status = "DECRYPT_CLIENT_KEY"; + goto egress; + } + state->client_keyblock.enctype = useenctype; + state->rock.client_key = client_key; } - state->client_keyblock.enctype = useenctype; /* Start assembling the response */ state->reply.msg_type = KRB5_AS_REP; @@ -248,6 +243,14 @@ finish_process_as_req(struct as_req_state *state, krb5_error_code errcode) goto egress; } + /* If we didn't find a client long-term key and no preauth mechanism + * replaced the reply key, error out now. */ + if (state->client_keyblock.enctype == ENCTYPE_NULL) { + state->status = "CANT_FIND_CLIENT_KEY"; + errcode = KRB5KDC_ERR_ETYPE_NOSUPP; + goto egress; + } + errcode = handle_authdata(kdc_context, state->c_flags, state->client, @@ -306,7 +309,8 @@ finish_process_as_req(struct as_req_state *state, krb5_error_code errcode) &state->reply_encpart, 0, as_encrypting_key, &state->reply, &response); - state->reply.enc_part.kvno = client_key->key_data_kvno; + if (client_key != NULL) + state->reply.enc_part.kvno = client_key->key_data_kvno; if (errcode) { state->status = "ENCODE_KDC_REP"; goto egress; diff --git a/src/kdc/kdc_preauth.c b/src/kdc/kdc_preauth.c index 5c3b615..5d12346 100644 --- a/src/kdc/kdc_preauth.c +++ b/src/kdc/kdc_preauth.c @@ -1473,6 +1473,9 @@ etype_info_as_rep_helper(krb5_context context, krb5_pa_data * padata, krb5_etype_info_entry **entry = NULL; krb5_data *scratch = NULL; + if (client_key == NULL) + return 0; + /* * Skip PA-ETYPE-INFO completely if AS-REQ lists any "newer" * enctypes. @@ -1576,6 +1579,9 @@ return_pw_salt(krb5_context context, krb5_pa_data *in_padata, krb5_key_data * client_key = rock->client_key; int i; + if (client_key == NULL) + return 0; + for (i = 0; i < request->nktypes; i++) { if (enctype_requires_etype_info_2(request->ktype[i])) return 0; -- 1.8.2.1