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authorKarolin Seeger <kseeger@samba.org>2019-05-14 06:25:01 (GMT)
committerKarolin Seeger <kseeger@samba.org>2019-05-14 06:25:01 (GMT)
commit1a248d16ab941491edcbf2ac8ba0f88cd7c65c29 (patch)
tree1a63efc21f43ce8a8daf0e202b3e1c8f097d15fc
parentd7fef72c6a373e10289675ef180d49d739cd6a5b (diff)
parenta72d4598bf4a2186769f25050663f4779ea581e0 (diff)
downloadsamba-1a248d16ab941491edcbf2ac8ba0f88cd7c65c29.tar.gz
Merge tag 'samba-4.8.12' into v4-8-test
samba: tag release samba-4.8.12
-rw-r--r--WHATSNEW.txt58
-rw-r--r--source4/heimdal/kdc/krb5tgs.c7
-rw-r--r--source4/torture/krb5/kdc-canon-heimdal.c115
3 files changed, 174 insertions, 6 deletions
diff --git a/WHATSNEW.txt b/WHATSNEW.txt
index b51ba11..3b8f058 100644
--- a/WHATSNEW.txt
+++ b/WHATSNEW.txt
@@ -1,4 +1,58 @@
==============================
+ Release Notes for Samba 4.8.12
+ May 14, 2019
+ ==============================
+
+
+This is a security release in order to address the following defect:
+
+o CVE-2018-16860 (Samba AD DC S4U2Self/S4U2Proxy unkeyed checksum)
+
+
+=======
+Details
+=======
+
+o CVE-2018-16860:
+ The checksum validation in the S4U2Self handler in the embedded Heimdal KDC
+ did not first confirm that the checksum was keyed, allowing replacement of
+ the requested target (client) principal.
+
+For more details and workarounds, please refer to the security advisory.
+
+
+Changes since 4.8.11:
+---------------------
+
+o Isaac Boukris <iboukris@gmail.com>
+ * BUG 13685: CVE-2018-16860: Heimdal KDC: Reject PA-S4U2Self with unkeyed
+ checksum.
+
+
+#######################################
+Reporting bugs & Development Discussion
+#######################################
+
+Please discuss this release on the samba-technical mailing list or by
+joining the #samba-technical IRC channel on irc.freenode.net.
+
+If you do report problems then please try to send high quality
+feedback. If you don't provide vital information to help us track down
+the problem then you will probably be ignored. All bug reports should
+be filed under the "Samba 4.1 and newer" product in the project's Bugzilla
+database (https://bugzilla.samba.org/).
+
+
+======================================================================
+== Our Code, Our Bugs, Our Responsibility.
+== The Samba Team
+======================================================================
+
+
+Release notes for older releases follow:
+----------------------------------------
+
+ ==============================
Release Notes for Samba 4.8.11
April 8, 2019
==============================
@@ -49,8 +103,8 @@ database (https://bugzilla.samba.org/).
======================================================================
-Release notes for older releases follow:
-----------------------------------------
+----------------------------------------------------------------------
+
==============================
Release Notes for Samba 4.8.10
diff --git a/source4/heimdal/kdc/krb5tgs.c b/source4/heimdal/kdc/krb5tgs.c
index a888788..ff7d931 100644
--- a/source4/heimdal/kdc/krb5tgs.c
+++ b/source4/heimdal/kdc/krb5tgs.c
@@ -1925,6 +1925,13 @@ server_lookup:
goto out;
}
+ if (!krb5_checksum_is_keyed(context, self.cksum.cksumtype)) {
+ free_PA_S4U2Self(&self);
+ kdc_log(context, config, 0, "Reject PA-S4U2Self with unkeyed checksum");
+ ret = KRB5KRB_AP_ERR_INAPP_CKSUM;
+ goto out;
+ }
+
ret = _krb5_s4u2self_to_checksumdata(context, &self, &datack);
if (ret)
goto out;
diff --git a/source4/torture/krb5/kdc-canon-heimdal.c b/source4/torture/krb5/kdc-canon-heimdal.c
index 7f806e7..1b2af2d 100644
--- a/source4/torture/krb5/kdc-canon-heimdal.c
+++ b/source4/torture/krb5/kdc-canon-heimdal.c
@@ -43,7 +43,9 @@
#define TEST_UPN 0x0000040
#define TEST_S4U2SELF 0x0000080
#define TEST_REMOVEDOLLAR 0x0000100
-#define TEST_ALL 0x00001FF
+#define TEST_AS_REQ_SPN 0x0000200 /* not used */
+#define TEST_MITM_S4U2SELF 0x0000400
+#define TEST_ALL 0x00007FF
struct test_data {
const char *test_name;
@@ -61,6 +63,7 @@ struct test_data {
bool upn;
bool other_upn_suffix;
bool s4u2self;
+ bool mitm_s4u2self;
bool removedollar;
const char *krb5_service;
const char *krb5_hostname;
@@ -209,6 +212,67 @@ static bool test_accept_ticket(struct torture_context *tctx,
return true;
}
+krb5_error_code
+_krb5_s4u2self_to_checksumdata(krb5_context context,
+ const PA_S4U2Self *self,
+ krb5_data *data);
+
+/* Helper function to modify the principal in PA_FOR_USER padata */
+static bool change_for_user_principal(struct torture_krb5_context *test_context,
+ krb5_data *modified_send_buf)
+{
+ PA_DATA *for_user;
+ int i = 0;
+ size_t used;
+ krb5_error_code ret;
+ PA_S4U2Self self, mod_self;
+ krb5_data cksum_data;
+ krb5_principal admin;
+ heim_octet_string orig_padata_value;
+ krb5_context k5_ctx = test_context->smb_krb5_context->krb5_context;
+
+ for_user = krb5_find_padata(test_context->tgs_req.padata->val,
+ test_context->tgs_req.padata->len, KRB5_PADATA_FOR_USER, &i);
+ torture_assert(test_context->tctx, for_user != NULL, "No PA_FOR_USER in s4u2self request");
+ orig_padata_value = for_user->padata_value;
+
+ torture_assert_int_equal(test_context->tctx,
+ krb5_make_principal(k5_ctx, &admin, test_context->test_data->realm,
+ "Administrator", NULL),
+ 0, "krb5_make_principal() failed");
+ torture_assert_int_equal(test_context->tctx,
+ decode_PA_S4U2Self(for_user->padata_value.data,
+ for_user->padata_value.length, &self, NULL),
+ 0, "decode_PA_S4U2Self() failed");
+ mod_self = self;
+ mod_self.name = admin->name;
+
+ torture_assert_int_equal(test_context->tctx,
+ _krb5_s4u2self_to_checksumdata(k5_ctx, &mod_self, &cksum_data),
+ 0, "_krb5_s4u2self_to_checksumdata() failed");
+ torture_assert_int_equal(test_context->tctx,
+ krb5_create_checksum(k5_ctx, NULL, KRB5_KU_OTHER_CKSUM,
+ CKSUMTYPE_CRC32, cksum_data.data,
+ cksum_data.length, &mod_self.cksum),
+ 0, "krb5_create_checksum() failed");
+
+ ASN1_MALLOC_ENCODE(PA_S4U2Self, for_user->padata_value.data, for_user->padata_value.length,
+ &mod_self, &used, ret);
+ torture_assert(test_context->tctx, ret == 0, "Failed to encode PA_S4U2Self ASN1 struct");
+ ASN1_MALLOC_ENCODE(TGS_REQ, modified_send_buf->data, modified_send_buf->length,
+ &test_context->tgs_req, &used, ret);
+ torture_assert(test_context->tctx, ret == 0, "Failed to encode TGS_REQ ASN1 struct");
+
+ free(for_user->padata_value.data);
+ for_user->padata_value = orig_padata_value;
+
+ free_PA_S4U2Self(&self);
+ krb5_data_free(&cksum_data);
+ free_Checksum(&mod_self.cksum);
+
+ return true;
+}
+
/*
* TEST_AS_REQ and TEST_AS_REQ_SELF - SEND
*
@@ -598,7 +662,12 @@ static bool torture_krb5_pre_send_tgs_req_canon_test(struct torture_krb5_context
}
- *modified_send_buf = *send_buf;
+ if (test_context->test_data->mitm_s4u2self) {
+ torture_assert(test_context->tctx, change_for_user_principal(test_context, modified_send_buf),
+ "Failed to modify PA_FOR_USER principal name");
+ } else {
+ *modified_send_buf = *send_buf;
+ }
return true;
}
@@ -617,6 +686,7 @@ static bool torture_krb5_post_recv_tgs_req_canon_test(struct torture_krb5_contex
{
KRB_ERROR error;
size_t used;
+ krb5_error_code expected_error;
/*
* If this account did not have a servicePrincipalName, then
@@ -627,9 +697,13 @@ static bool torture_krb5_post_recv_tgs_req_canon_test(struct torture_krb5_contex
torture_assert_int_equal(test_context->tctx,
error.pvno, 5,
"Got wrong error.pvno");
+ expected_error = KRB5KDC_ERR_S_PRINCIPAL_UNKNOWN - KRB5KDC_ERR_NONE;
+ if (error.error_code != expected_error && test_context->test_data->mitm_s4u2self) {
+ expected_error = KRB5KRB_AP_ERR_INAPP_CKSUM - KRB5KDC_ERR_NONE;
+ }
torture_assert_int_equal(test_context->tctx,
error.error_code,
- KRB5KDC_ERR_S_PRINCIPAL_UNKNOWN - KRB5KDC_ERR_NONE,
+ expected_error,
"Got wrong error.error_code");
} else {
torture_assert_int_equal(test_context->tctx,
@@ -672,6 +746,8 @@ static bool torture_krb5_post_recv_tgs_req_canon_test(struct torture_krb5_contex
torture_assert_int_equal(test_context->tctx,
*test_context->tgs_rep.ticket.enc_part.kvno & 0xFFFF0000,
0, "Unexpecedly got a RODC number in the KVNO, should just be principal KVNO");
+ torture_assert(test_context->tctx, test_context->test_data->mitm_s4u2self == false,
+ "KDC accepted PA_S4U2Self with unkeyed checksum!");
free_TGS_REP(&test_context->tgs_rep);
}
torture_assert(test_context->tctx, test_context->packet_count == 0, "too many packets");
@@ -1845,7 +1921,23 @@ static bool torture_krb5_as_req_canon(struct torture_context *tctx, const void *
*/
if (torture_setting_bool(tctx, "expect_machine_account", false)
&& (test_data->enterprise || test_data->upn == false)) {
+
+ if (test_data->mitm_s4u2self) {
+ torture_assert_int_equal(tctx, k5ret, KRB5KRB_AP_ERR_INAPP_CKSUM,
+ assertion_message);
+ /* Done testing mitm-s4u2self */
+ return true;
+ }
+
torture_assert_int_equal(tctx, k5ret, 0, assertion_message);
+
+ /* Check that the impersonate principal is not being canonicalized by the KDC. */
+ if (test_data->s4u2self) {
+ torture_assert(tctx, krb5_principal_compare(k5_context, server_creds->client,
+ principal),
+ "TGS-REP cname does not match requested client principal");
+ }
+
torture_assert_int_equal(tctx, krb5_cc_store_cred(k5_context,
ccache, server_creds),
0, "krb5_cc_store_cred failed");
@@ -2222,11 +2314,25 @@ struct torture_suite *torture_krb5_canon(TALLOC_CTX *mem_ctx)
(i & TEST_NETBIOS_REALM) ? "netbios-realm" : "krb5-realm",
(i & TEST_WIN2K) ? "win2k" : "no-win2k",
(i & TEST_UPN) ? "upn" : "no-upn",
- (i & TEST_S4U2SELF) ? "s4u2self" : "normal",
+ (i & TEST_S4U2SELF) ? (i & TEST_MITM_S4U2SELF) ? "mitm-s4u2self" : "s4u2self" : "normal",
(i & TEST_REMOVEDOLLAR) ? "removedollar" : "keepdollar");
struct test_data *test_data = talloc_zero(suite, struct test_data);
+ if (i & TEST_MITM_S4U2SELF) {
+ if (!(i & TEST_S4U2SELF)) {
+ continue;
+ }
+ }
+
+ /*
+ * Due to backport: this flag is not used until Samba
+ * 4.10
+ */
+ if (i & TEST_AS_REQ_SPN) {
+ continue;
+ }
+
test_data->test_name = name;
test_data->real_realm
= strupper_talloc(test_data,
@@ -2246,6 +2352,7 @@ struct torture_suite *torture_krb5_canon(TALLOC_CTX *mem_ctx)
test_data->win2k = (i & TEST_WIN2K) != 0;
test_data->upn = (i & TEST_UPN) != 0;
test_data->s4u2self = (i & TEST_S4U2SELF) != 0;
+ test_data->mitm_s4u2self = (i & TEST_MITM_S4U2SELF) != 0;
test_data->removedollar = (i & TEST_REMOVEDOLLAR) != 0;
torture_suite_add_simple_tcase_const(suite, name, torture_krb5_as_req_canon,
test_data);