From 5d7ec9a00b6f4c6768c606d37d235415f2006445 Mon Sep 17 00:00:00 2001 From: Isaac Boukris Date: Fri, 27 Sep 2019 18:25:03 +0300 Subject: [PATCH 1/3] mit-kdc: add basic loacl realm S4U support Signed-off-by: Isaac Boukris Pair-Programmed-With: Andreas Schneider --- source4/kdc/mit-kdb/kdb_samba_policies.c | 124 +++++++++++------------ source4/kdc/mit_samba.c | 47 ++------- source4/kdc/mit_samba.h | 6 +- 3 files changed, 71 insertions(+), 106 deletions(-) diff --git a/source4/kdc/mit-kdb/kdb_samba_policies.c b/source4/kdc/mit-kdb/kdb_samba_policies.c index 793fe366c35..22534c09974 100644 --- a/source4/kdc/mit-kdb/kdb_samba_policies.c +++ b/source4/kdc/mit-kdb/kdb_samba_policies.c @@ -200,13 +200,17 @@ static krb5_error_code ks_verify_pac(krb5_context context, krb5_keyblock *krbtgt_key, krb5_timestamp authtime, krb5_authdata **tgt_auth_data, - krb5_pac *pac) + krb5_pac *out_pac) { struct mit_samba_context *mit_ctx; krb5_authdata **authdata = NULL; - krb5_pac ipac = NULL; - DATA_BLOB logon_data = { NULL, 0 }; + krb5_keyblock *header_server_key = NULL; + krb5_key_data *impersonator_kd = NULL; + krb5_keyblock impersonator_key = {0}; krb5_error_code code; + krb5_pac pac; + + *out_pac = NULL; mit_ctx = ks_get_context(context); if (mit_ctx == NULL) { @@ -238,41 +242,43 @@ static krb5_error_code ks_verify_pac(krb5_context context, code = krb5_pac_parse(context, authdata[0]->contents, authdata[0]->length, - &ipac); + &pac); if (code != 0) { goto done; } - /* TODO: verify this is correct - * - * In the constrained delegation case, the PAC is from a service - * ticket rather than a TGT; we must verify the server and KDC - * signatures to assert that the server did not forge the PAC. + /* + * For constrained delegation in MIT version < 1.18 we aren't provided + * with the 2nd ticket server key to verify the PAC. + * We can workaround that by fetching the key from the client db entry, + * which is the impersonator account in that version. + * TODO: use the provided entry in the new 1.18 version. */ if (flags & KRB5_KDB_FLAG_CONSTRAINED_DELEGATION) { - code = krb5_pac_verify(context, - ipac, - authtime, - client_princ, - server_key, - krbtgt_key); + /* The impersonator must be local. */ + if (client == NULL) { + code = KRB5KDC_ERR_BADOPTION; + goto done; + } + /* Fetch and decrypt 2nd ticket server's current key. */ + code = krb5_dbe_find_enctype(context, client, -1, -1, 0, + &impersonator_kd); + if (code != 0) { + goto done; + } + code = krb5_dbe_decrypt_key_data(context, NULL, + impersonator_kd, + &impersonator_key, NULL); + if (code != 0) { + goto done; + } + header_server_key = &impersonator_key; } else { - code = krb5_pac_verify(context, - ipac, - authtime, - client_princ, - krbtgt_key, - NULL); - } - if (code != 0) { - goto done; + header_server_key = krbtgt_key; } - /* check and update PAC */ - code = krb5_pac_parse(context, - authdata[0]->contents, - authdata[0]->length, - pac); + code = krb5_pac_verify(context, pac, authtime, client_princ, + header_server_key, NULL); if (code != 0) { goto done; } @@ -280,17 +286,22 @@ static krb5_error_code ks_verify_pac(krb5_context context, code = mit_samba_reget_pac(mit_ctx, context, flags, - client_princ, client, server, krbtgt, krbtgt_key, - pac); + &pac); + if (code != 0) { + goto done; + } + + *out_pac = pac; + pac = NULL; done: + krb5_free_keyblock_contents(context, &impersonator_key); krb5_free_authdata(context, authdata); - krb5_pac_free(context, ipac); - free(logon_data.data); + krb5_pac_free(context, pac); return code; } @@ -319,6 +330,7 @@ krb5_error_code kdb_samba_db_sign_auth_data(krb5_context context, krb5_authdata **pac_auth_data = NULL; krb5_authdata **authdata = NULL; krb5_boolean is_as_req; + krb5_const_principal pac_client; krb5_error_code code; krb5_pac pac = NULL; krb5_data pac_data; @@ -330,11 +342,6 @@ krb5_error_code kdb_samba_db_sign_auth_data(krb5_context context, krbtgt = krbtgt == NULL ? local_krbtgt : krbtgt; krbtgt_key = krbtgt_key == NULL ? local_krbtgt_key : krbtgt_key; - /* FIXME: We don't support S4U yet */ - if (flags & KRB5_KDB_FLAGS_S4U) { - return KRB5_KDB_DBTYPE_NOSUP; - } - is_as_req = ((flags & KRB5_KDB_FLAG_CLIENT_REFERRALS_ONLY) != 0); /* @@ -395,6 +402,16 @@ krb5_error_code kdb_samba_db_sign_auth_data(krb5_context context, ks_client_princ = client->princ; } + /* In protocol transition, we are currently not provided with the tgt + * client name to verify the PAC, we could probably skip the name + * verification and just verify the signatures, but since we don't + * support cross-realm nor aliases, we can just use server->princ */ + if (flags & KRB5_KDB_FLAG_PROTOCOL_TRANSITION) { + pac_client = server->princ; + } else { + pac_client = ks_client_princ; + } + if (client_entry == NULL) { client_entry = client; } @@ -469,7 +486,7 @@ krb5_error_code kdb_samba_db_sign_auth_data(krb5_context context, code = ks_verify_pac(context, flags, - ks_client_princ, + pac_client, client_entry, server, krbtgt, @@ -515,7 +532,7 @@ krb5_error_code kdb_samba_db_sign_auth_data(krb5_context context, is_as_req ? "AS-REQ" : "TGS-REQ", client_name); code = krb5_pac_sign(context, pac, authtime, ks_client_princ, - server_key, krbtgt_key, &pac_data); + server_key, krbtgt_key, &pac_data); if (code != 0) { DBG_ERR("krb5_pac_sign failed: %d\n", code); goto done; @@ -541,12 +558,6 @@ krb5_error_code kdb_samba_db_sign_auth_data(krb5_context context, KRB5_AUTHDATA_IF_RELEVANT, authdata, signed_auth_data); - if (code != 0) { - goto done; - } - - code = 0; - done: if (client_entry != NULL && client_entry != client) { ks_free_principal(context, client_entry); @@ -572,32 +583,13 @@ krb5_error_code kdb_samba_db_check_allowed_to_delegate(krb5_context context, * server; -> delegating service * proxy; -> target principal */ - krb5_db_entry *delegating_service = discard_const_p(krb5_db_entry, server); - - char *target_name = NULL; - bool is_enterprise; - krb5_error_code code; mit_ctx = ks_get_context(context); if (mit_ctx == NULL) { return KRB5_KDB_DBNOTINITED; } - code = krb5_unparse_name(context, proxy, &target_name); - if (code) { - goto done; - } - - is_enterprise = (proxy->type == KRB5_NT_ENTERPRISE_PRINCIPAL); - - code = mit_samba_check_s4u2proxy(mit_ctx, - delegating_service, - target_name, - is_enterprise); - -done: - free(target_name); - return code; + return mit_samba_check_s4u2proxy(mit_ctx, server, proxy); } diff --git a/source4/kdc/mit_samba.c b/source4/kdc/mit_samba.c index cb72b5de294..03c2c2ea1de 100644 --- a/source4/kdc/mit_samba.c +++ b/source4/kdc/mit_samba.c @@ -517,7 +517,6 @@ int mit_samba_get_pac(struct mit_samba_context *smb_ctx, krb5_error_code mit_samba_reget_pac(struct mit_samba_context *ctx, krb5_context context, int flags, - krb5_const_principal client_principal, krb5_db_entry *client, krb5_db_entry *server, krb5_db_entry *krbtgt, @@ -689,7 +688,7 @@ krb5_error_code mit_samba_reget_pac(struct mit_samba_context *ctx, context, *pac, server->princ, - discard_const(client_principal), + client->princ, deleg_blob); if (!NT_STATUS_IS_OK(nt_status)) { DEBUG(0, ("Update delegation info failed: %s\n", @@ -1081,41 +1080,17 @@ int mit_samba_check_client_access(struct mit_samba_context *ctx, } int mit_samba_check_s4u2proxy(struct mit_samba_context *ctx, - krb5_db_entry *kentry, - const char *target_name, - bool is_nt_enterprise_name) + const krb5_db_entry *server, + krb5_const_principal target_principal) { -#if 1 - /* - * This is disabled because mit_samba_update_pac_data() does not handle - * S4U_DELEGATION_INFO - */ - - return KRB5KDC_ERR_BADOPTION; -#else - krb5_principal target_principal; - int flags = 0; - int ret; - - if (is_nt_enterprise_name) { - flags = KRB5_PRINCIPAL_PARSE_ENTERPRISE; - } - - ret = krb5_parse_name_flags(ctx->context, target_name, - flags, &target_principal); - if (ret) { - return ret; - } - - ret = samba_kdc_check_s4u2proxy(ctx->context, - ctx->db_ctx, - skdc_entry, - target_principal); - - krb5_free_principal(ctx->context, target_principal); - - return ret; -#endif + struct samba_kdc_entry *server_skdc_entry = + talloc_get_type_abort(server->e_data, + struct samba_kdc_entry); + + return samba_kdc_check_s4u2proxy(ctx->context, + ctx->db_ctx, + server_skdc_entry, + target_principal); } static krb5_error_code mit_samba_change_pwd_error(krb5_context context, diff --git a/source4/kdc/mit_samba.h b/source4/kdc/mit_samba.h index 4431e82a1b2..9370ab533af 100644 --- a/source4/kdc/mit_samba.h +++ b/source4/kdc/mit_samba.h @@ -57,7 +57,6 @@ int mit_samba_get_pac(struct mit_samba_context *smb_ctx, krb5_error_code mit_samba_reget_pac(struct mit_samba_context *ctx, krb5_context context, int flags, - krb5_const_principal client_principal, krb5_db_entry *client, krb5_db_entry *server, krb5_db_entry *krbtgt, @@ -74,9 +73,8 @@ int mit_samba_check_client_access(struct mit_samba_context *ctx, DATA_BLOB *e_data); int mit_samba_check_s4u2proxy(struct mit_samba_context *ctx, - krb5_db_entry *kentry, - const char *target_name, - bool is_nt_enterprise_name); + const krb5_db_entry *server, + krb5_const_principal target_principal); int mit_samba_kpasswd_change_password(struct mit_samba_context *ctx, char *pwd, -- 2.37.1 From 325912375cf54743ab8ea557172a72b870002e9f Mon Sep 17 00:00:00 2001 From: Isaac Boukris Date: Fri, 27 Sep 2019 18:35:30 +0300 Subject: [PATCH 2/3] krb5-mit: enable S4U client support for MIT build Signed-off-by: Isaac Boukris Pair-Programmed-With: Andreas Schneider --- lib/krb5_wrap/krb5_samba.c | 185 ++++++++++++++++++++++++++ lib/krb5_wrap/krb5_samba.h | 2 - source4/auth/kerberos/kerberos_util.c | 11 -- 3 files changed, 185 insertions(+), 13 deletions(-) diff --git a/lib/krb5_wrap/krb5_samba.c b/lib/krb5_wrap/krb5_samba.c index 4321f07ca09..3fd95e47fca 100644 --- a/lib/krb5_wrap/krb5_samba.c +++ b/lib/krb5_wrap/krb5_samba.c @@ -2702,6 +2702,191 @@ krb5_error_code smb_krb5_kinit_s4u2_ccache(krb5_context ctx, return 0; } + +#else /* MIT */ + +static bool princ_compare_no_dollar(krb5_context ctx, + krb5_principal a, + krb5_principal b) +{ + bool cmp; + krb5_principal mod = NULL; + + if (a->length == 1 && b->length == 1 && + a->data[0].length != 0 && b->data[0].length != 0 && + a->data[0].data[a->data[0].length -1] != + b->data[0].data[b->data[0].length -1]) { + if (a->data[0].data[a->data[0].length -1] == '$') { + mod = a; + mod->data[0].length--; + } else if (b->data[0].data[b->data[0].length -1] == '$') { + mod = b; + mod->data[0].length--; + } + } + + cmp = krb5_principal_compare_flags(ctx, a, b, + KRB5_PRINCIPAL_COMPARE_CASEFOLD); + + if (mod != NULL) { + mod->data[0].length++; + } + + return cmp; +} + +krb5_error_code smb_krb5_kinit_s4u2_ccache(krb5_context ctx, + krb5_ccache store_cc, + krb5_principal init_principal, + const char *init_password, + krb5_principal impersonate_principal, + const char *self_service, + const char *target_service, + krb5_get_init_creds_opt *krb_options, + time_t *expire_time, + time_t *kdc_time) +{ + krb5_error_code code; + krb5_principal self_princ = NULL; + krb5_principal target_princ = NULL; + krb5_creds *store_creds; + krb5_creds *s4u2self_creds = NULL; + krb5_creds *s4u2proxy_creds = NULL; + krb5_creds init_creds = {0}; + krb5_creds mcreds = {0}; + krb5_flags options = KRB5_GC_NO_STORE; + krb5_ccache tmp_cc; + bool s4u2proxy; + + code = krb5_cc_new_unique(ctx, "MEMORY", NULL, &tmp_cc); + if (code != 0) { + return code; + } + + code = krb5_get_init_creds_password(ctx, &init_creds, + init_principal, + init_password, + NULL, NULL, + 0, + NULL, + krb_options); + if (code != 0) { + goto done; + } + + code = krb5_cc_initialize(ctx, tmp_cc, init_creds.client); + if (code != 0) { + goto done; + } + + code = krb5_cc_store_cred(ctx, tmp_cc, &init_creds); + if (code != 0) { + goto done; + } + + /* + * Check if we also need S4U2Proxy or if S4U2Self is + * enough in order to get a ticket for the target. + */ + if (target_service == NULL) { + s4u2proxy = false; + } else if (strcmp(target_service, self_service) == 0) { + s4u2proxy = false; + } else { + s4u2proxy = true; + } + + code = krb5_parse_name(ctx, self_service, &self_princ); + if (code != 0) { + goto done; + } + + /* MIT lacks aliases support in S4U, for S4U2Self we require the tgt + * client and the request server to be the same principal name. */ + if (!princ_compare_no_dollar(ctx, init_creds.client, self_princ)) { + code = KRB5KDC_ERR_PADATA_TYPE_NOSUPP; + goto done; + } + + mcreds.client = impersonate_principal; + mcreds.server = init_creds.client; + + code = krb5_get_credentials_for_user(ctx, options, tmp_cc, &mcreds, + NULL, &s4u2self_creds); + if (code != 0) { + goto done; + } + + if (s4u2proxy) { + code = krb5_parse_name(ctx, target_service, &target_princ); + if (code != 0) { + goto done; + } + + mcreds.client = init_creds.client; + mcreds.server = target_princ; + mcreds.second_ticket = s4u2self_creds->ticket; + + code = krb5_get_credentials(ctx, options | + KRB5_GC_CONSTRAINED_DELEGATION, + tmp_cc, &mcreds, &s4u2proxy_creds); + if (code != 0) { + goto done; + } + + /* Check KDC support of S4U2Proxy extension */ + if (!krb5_principal_compare(ctx, s4u2self_creds->client, + s4u2proxy_creds->client)) { + code = KRB5KDC_ERR_PADATA_TYPE_NOSUPP; + goto done; + } + + store_creds = s4u2proxy_creds; + } else { + store_creds = s4u2self_creds;; + + /* We need to save the ticket with the requested server name + * or the caller won't be able to find it in cache. */ + if (!krb5_principal_compare(ctx, self_princ, + store_creds->server)) { + krb5_free_principal(ctx, store_creds->server); + store_creds->server = NULL; + code = krb5_copy_principal(ctx, self_princ, + &store_creds->server); + if (code != 0) { + goto done; + } + } + } + + code = krb5_cc_initialize(ctx, store_cc, store_creds->client); + if (code != 0) { + goto done; + } + + code = krb5_cc_store_cred(ctx, store_cc, store_creds); + if (code != 0) { + goto done; + } + + if (expire_time) { + *expire_time = (time_t) store_creds->times.endtime; + } + + if (kdc_time) { + *kdc_time = (time_t) store_creds->times.starttime; + } + +done: + krb5_cc_destroy(ctx, tmp_cc); + krb5_free_cred_contents(ctx, &init_creds); + krb5_free_creds(ctx, s4u2self_creds); + krb5_free_creds(ctx, s4u2proxy_creds); + krb5_free_principal(ctx, self_princ); + krb5_free_principal(ctx, target_princ); + + return code; +} #endif #if !defined(HAVE_KRB5_MAKE_PRINCIPAL) && defined(HAVE_KRB5_BUILD_PRINCIPAL_ALLOC_VA) diff --git a/lib/krb5_wrap/krb5_samba.h b/lib/krb5_wrap/krb5_samba.h index a66b7465530..c8573f52bd9 100644 --- a/lib/krb5_wrap/krb5_samba.h +++ b/lib/krb5_wrap/krb5_samba.h @@ -252,7 +252,6 @@ krb5_error_code smb_krb5_kinit_password_ccache(krb5_context ctx, krb5_get_init_creds_opt *krb_options, time_t *expire_time, time_t *kdc_time); -#ifdef SAMBA4_USES_HEIMDAL krb5_error_code smb_krb5_kinit_s4u2_ccache(krb5_context ctx, krb5_ccache store_cc, krb5_principal init_principal, @@ -263,7 +262,6 @@ krb5_error_code smb_krb5_kinit_s4u2_ccache(krb5_context ctx, krb5_get_init_creds_opt *krb_options, time_t *expire_time, time_t *kdc_time); -#endif #if defined(HAVE_KRB5_MAKE_PRINCIPAL) #define smb_krb5_make_principal krb5_make_principal diff --git a/source4/auth/kerberos/kerberos_util.c b/source4/auth/kerberos/kerberos_util.c index 544d9d853cc..c14d8c72d8c 100644 --- a/source4/auth/kerberos/kerberos_util.c +++ b/source4/auth/kerberos/kerberos_util.c @@ -234,9 +234,7 @@ done: { krb5_error_code ret; const char *password; -#ifdef SAMBA4_USES_HEIMDAL const char *self_service; -#endif const char *target_service; time_t kdc_time = 0; krb5_principal princ; @@ -268,9 +266,7 @@ done: return ret; } -#ifdef SAMBA4_USES_HEIMDAL self_service = cli_credentials_get_self_service(credentials); -#endif target_service = cli_credentials_get_target_service(credentials); password = cli_credentials_get_password(credentials); @@ -331,7 +327,6 @@ done: #endif if (password) { if (impersonate_principal) { -#ifdef SAMBA4_USES_HEIMDAL ret = smb_krb5_kinit_s4u2_ccache(smb_krb5_context->krb5_context, ccache, princ, @@ -342,12 +337,6 @@ done: krb_options, NULL, &kdc_time); -#else - talloc_free(mem_ctx); - (*error_string) = "INTERNAL error: s4u2 ops " - "are not supported with MIT build yet"; - return EINVAL; -#endif } else { ret = smb_krb5_kinit_password_ccache(smb_krb5_context->krb5_context, ccache, -- 2.37.1 From a5713b1558192f24348f7794da84bf65cf78e6ec Mon Sep 17 00:00:00 2001 From: Isaac Boukris Date: Sat, 19 Sep 2020 14:16:20 +0200 Subject: [PATCH 3/3] wip: for canonicalization with new MIT kdc code --- source4/kdc/mit_samba.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/source4/kdc/mit_samba.c b/source4/kdc/mit_samba.c index 03c2c2ea1de..30fade56531 100644 --- a/source4/kdc/mit_samba.c +++ b/source4/kdc/mit_samba.c @@ -232,6 +232,9 @@ int mit_samba_get_principal(struct mit_samba_context *ctx, if (kflags & KRB5_KDB_FLAG_CANONICALIZE) { sflags |= SDB_F_CANON; } +#if KRB5_KDB_API_VERSION >= 10 + sflags |= SDB_F_FORCE_CANON; +#endif if (kflags & (KRB5_KDB_FLAG_CLIENT_REFERRALS_ONLY | KRB5_KDB_FLAG_INCLUDE_PAC)) { /* -- 2.37.1