From 9ef9746bca73a939ad04b1df07caeb70921bc3de Mon Sep 17 00:00:00 2001 From: Andrew Bartlett Date: Thu, 12 Aug 2021 11:10:09 +1200 Subject: [PATCH] CVE-2020-25722 dsdb: Move krbtgt password setup after the point of checking if any passwords are changed This allows the add of an RODC, before setting the password, to avoid this module, which helps isolate testing of security around the msDS-SecondaryKrbTgtNumber attribute. BUG: https://bugzilla.samba.org/show_bug.cgi?id=14703 Signed-off-by: Andrew Bartlett Reviewed-by: Douglas Bagnall --- selftest/knownfail.d/priv_attr | 12 +- .../dsdb/samdb/ldb_modules/password_hash.c | 106 +++++++++--------- 2 files changed, 57 insertions(+), 61 deletions(-) diff --git a/selftest/knownfail.d/priv_attr b/selftest/knownfail.d/priv_attr index 31b9cb23b44..ab6db192aae 100644 --- a/selftest/knownfail.d/priv_attr +++ b/selftest/knownfail.d/priv_attr @@ -14,14 +14,10 @@ samba4.priv_attrs.python\(.*\).__main__.PrivAttrsTests.test_priv_attr_userAccoun samba4.priv_attrs.python\(.*\).__main__.PrivAttrsTests.test_priv_attr_userAccountControl-a2d-user_add_admin-add_WP_user samba4.priv_attrs.python\(.*\).__main__.PrivAttrsTests.test_priv_attr_userAccountControl-a2d-user_add_admin-add_default_computer samba4.priv_attrs.python\(.*\).__main__.PrivAttrsTests.test_priv_attr_userAccountControl-a2d-user_add_admin-add_default_user -samba4.priv_attrs.python\(.*\).__main__.PrivAttrsTests.test_priv_attr_msDS-SecondaryKrbTgtNumber_add_admin-add_WP_computer -samba4.priv_attrs.python\(.*\).__main__.PrivAttrsTests.test_priv_attr_msDS-SecondaryKrbTgtNumber_add_admin-add_WP_user -samba4.priv_attrs.python\(.*\).__main__.PrivAttrsTests.test_priv_attr_msDS-SecondaryKrbTgtNumber_add_admin-add_default_computer -samba4.priv_attrs.python\(.*\).__main__.PrivAttrsTests.test_priv_attr_msDS-SecondaryKrbTgtNumber_add_admin-add_default_user -samba4.priv_attrs.strict.python\(.*\).__main__.PrivAttrsTests.test_priv_attr_msDS-SecondaryKrbTgtNumber_add_admin-add_WP_computer -samba4.priv_attrs.strict.python\(.*\).__main__.PrivAttrsTests.test_priv_attr_msDS-SecondaryKrbTgtNumber_add_admin-add_WP_user -samba4.priv_attrs.strict.python\(.*\).__main__.PrivAttrsTests.test_priv_attr_msDS-SecondaryKrbTgtNumber_add_admin-add_default_computer -samba4.priv_attrs.strict.python\(.*\).__main__.PrivAttrsTests.test_priv_attr_msDS-SecondaryKrbTgtNumber_add_admin-add_default_user +samba4.priv_attrs.python\(.*\).__main__.PrivAttrsTests.test_priv_attr_msDS-SecondaryKrbTgtNumber_add_CC_WP_computer +samba4.priv_attrs.python\(.*\).__main__.PrivAttrsTests.test_priv_attr_msDS-SecondaryKrbTgtNumber_add_CC_WP_user +samba4.priv_attrs.python\(.*\).__main__.PrivAttrsTests.test_priv_attr_msDS-SecondaryKrbTgtNumber_add_CC_default_computer +samba4.priv_attrs.python\(.*\).__main__.PrivAttrsTests.test_priv_attr_msDS-SecondaryKrbTgtNumber_add_CC_default_user samba4.priv_attrs.strict.python\(.*\).__main__.PrivAttrsTests.test_priv_attr_msDS-AllowedToDelegateTo_add_CC_WP_computer samba4.priv_attrs.strict.python\(.*\).__main__.PrivAttrsTests.test_priv_attr_msDS-AllowedToDelegateTo_add_CC_WP_user samba4.priv_attrs.strict.python\(.*\).__main__.PrivAttrsTests.test_priv_attr_msDS-AllowedToDelegateTo_add_CC_default_computer diff --git a/source4/dsdb/samdb/ldb_modules/password_hash.c b/source4/dsdb/samdb/ldb_modules/password_hash.c index 7ecf8c43040..47af8c8733c 100644 --- a/source4/dsdb/samdb/ldb_modules/password_hash.c +++ b/source4/dsdb/samdb/ldb_modules/password_hash.c @@ -2496,6 +2496,59 @@ static int setup_password_fields(struct setup_password_fields_io *io) return LDB_SUCCESS; } + if (io->u.is_krbtgt) { + size_t min = 196; + size_t max = 255; + size_t diff = max - min; + size_t len = max; + struct ldb_val *krbtgt_utf16 = NULL; + + if (!io->ac->pwd_reset) { + return dsdb_module_werror(io->ac->module, + LDB_ERR_ATTRIBUTE_OR_VALUE_EXISTS, + WERR_DS_ATT_ALREADY_EXISTS, + "Password change on krbtgt not permitted!"); + } + + if (io->n.cleartext_utf16 == NULL) { + return dsdb_module_werror(io->ac->module, + LDB_ERR_UNWILLING_TO_PERFORM, + WERR_DS_INVALID_ATTRIBUTE_SYNTAX, + "Password reset on krbtgt requires UTF16!"); + } + + /* + * Instead of taking the callers value, + * we just generate a new random value here. + * + * Include null termination in the array. + */ + if (diff > 0) { + size_t tmp; + + generate_random_buffer((uint8_t *)&tmp, sizeof(tmp)); + + tmp %= diff; + + len = min + tmp; + } + + krbtgt_utf16 = talloc_zero(io->ac, struct ldb_val); + if (krbtgt_utf16 == NULL) { + return ldb_oom(ldb); + } + + *krbtgt_utf16 = data_blob_talloc_zero(krbtgt_utf16, + (len+1)*2); + if (krbtgt_utf16->data == NULL) { + return ldb_oom(ldb); + } + krbtgt_utf16->length = len * 2; + generate_secret_buffer(krbtgt_utf16->data, + krbtgt_utf16->length); + io->n.cleartext_utf16 = krbtgt_utf16; + } + /* transform the old password (for password changes) */ ret = setup_given_passwords(io, &io->og); if (ret != LDB_SUCCESS) { @@ -3673,59 +3726,6 @@ static int setup_io(struct ph_context *ac, return ldb_operr(ldb); } - if (io->u.is_krbtgt) { - size_t min = 196; - size_t max = 255; - size_t diff = max - min; - size_t len = max; - struct ldb_val *krbtgt_utf16 = NULL; - - if (!ac->pwd_reset) { - return dsdb_module_werror(ac->module, - LDB_ERR_ATTRIBUTE_OR_VALUE_EXISTS, - WERR_DS_ATT_ALREADY_EXISTS, - "Password change on krbtgt not permitted!"); - } - - if (io->n.cleartext_utf16 == NULL) { - return dsdb_module_werror(ac->module, - LDB_ERR_UNWILLING_TO_PERFORM, - WERR_DS_INVALID_ATTRIBUTE_SYNTAX, - "Password reset on krbtgt requires UTF16!"); - } - - /* - * Instead of taking the callers value, - * we just generate a new random value here. - * - * Include null termination in the array. - */ - if (diff > 0) { - size_t tmp; - - generate_random_buffer((uint8_t *)&tmp, sizeof(tmp)); - - tmp %= diff; - - len = min + tmp; - } - - krbtgt_utf16 = talloc_zero(io->ac, struct ldb_val); - if (krbtgt_utf16 == NULL) { - return ldb_oom(ldb); - } - - *krbtgt_utf16 = data_blob_talloc_zero(krbtgt_utf16, - (len+1)*2); - if (krbtgt_utf16->data == NULL) { - return ldb_oom(ldb); - } - krbtgt_utf16->length = len * 2; - generate_secret_buffer(krbtgt_utf16->data, - krbtgt_utf16->length); - io->n.cleartext_utf16 = krbtgt_utf16; - } - if (existing_msg != NULL) { NTSTATUS status; -- 2.47.2