98 lines
3.2 KiB
Diff
98 lines
3.2 KiB
Diff
From f1c64ed29ea0911beaa1cd3b80915ef5b44085af Mon Sep 17 00:00:00 2001
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From: Andrew Bartlett <abartlet@samba.org>
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Date: Mon, 1 Nov 2021 17:19:29 +1300
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Subject: [PATCH 137/266] CVE-2020-25722 Check all elements in acl_check_spn()
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not just the first one
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Thankfully we are aleady in a loop over all the message elements in
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acl_modify() so this is an easy and safe change to make.
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BUG: https://bugzilla.samba.org/show_bug.cgi?id=14876
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Signed-off-by: Andrew Bartlett <abartlet@samba.org>
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Reviewed-by: Joseph Sutton <josephsutton@catalyst.net.nz>
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Conflict:remove test
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Reference:https://gitlab.com/samba-team/samba/-/commit/f1c64ed29ea0911beaa1cd3b80915ef5b44085af
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---
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source4/dsdb/samdb/ldb_modules/acl.c | 31 +++++++++++++++++++++-------
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1 files changed, 23 insertions(+), 8 deletions(-)
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delete mode 100644 selftest/knownfail.d/acl-spn
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diff --git a/source4/dsdb/samdb/ldb_modules/acl.c b/source4/dsdb/samdb/ldb_modules/acl.c
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index 9cae15881de..d0b3da4d9e8 100644
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--- a/source4/dsdb/samdb/ldb_modules/acl.c
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+++ b/source4/dsdb/samdb/ldb_modules/acl.c
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@@ -653,9 +653,14 @@ success:
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return LDB_SUCCESS;
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}
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+/*
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+ * Passing in 'el' is critical, we want to check all the values.
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+ *
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+ */
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static int acl_check_spn(TALLOC_CTX *mem_ctx,
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struct ldb_module *module,
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struct ldb_request *req,
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+ const struct ldb_message_element *el,
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struct security_descriptor *sd,
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struct dom_sid *sid,
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const struct dsdb_attribute *attr,
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@@ -667,7 +672,6 @@ static int acl_check_spn(TALLOC_CTX *mem_ctx,
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struct ldb_context *ldb = ldb_module_get_ctx(module);
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struct ldb_result *acl_res;
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struct ldb_result *netbios_res;
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- struct ldb_message_element *el;
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struct ldb_dn *partitions_dn = samdb_partitions_dn(ldb, tmp_ctx);
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uint32_t userAccountControl;
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const char *samAccountName;
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@@ -717,6 +721,23 @@ static int acl_check_spn(TALLOC_CTX *mem_ctx,
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return ret;
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}
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+ /*
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+ * If we have "validated write spn", allow delete of any
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+ * existing value (this keeps constrained delete to the same
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+ * rules as unconstrained)
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+ */
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+ if (req->operation == LDB_MODIFY) {
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+ /*
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+ * If not add or replace (eg delete),
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+ * return success
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+ */
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+ if ((el->flags
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+ & (LDB_FLAG_MOD_ADD|LDB_FLAG_MOD_REPLACE)) == 0) {
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+ talloc_free(tmp_ctx);
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+ return LDB_SUCCESS;
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+ }
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+ }
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+
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ret = dsdb_module_search_dn(module, tmp_ctx,
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&acl_res, req->op.mod.message->dn,
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acl_attrs,
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@@ -745,13 +766,6 @@ static int acl_check_spn(TALLOC_CTX *mem_ctx,
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netbios_name = ldb_msg_find_attr_as_string(netbios_res->msgs[0], "nETBIOSName", NULL);
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- el = ldb_msg_find_element(req->op.mod.message, "servicePrincipalName");
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- if (!el) {
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- talloc_free(tmp_ctx);
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- return ldb_error(ldb, LDB_ERR_OPERATIONS_ERROR,
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- "Error finding element for servicePrincipalName.");
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- }
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-
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/* NTDSDSA objectGuid of object we are checking SPN for */
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if (userAccountControl & (UF_SERVER_TRUST_ACCOUNT | UF_PARTIAL_SECRETS_ACCOUNT)) {
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ret = dsdb_module_find_ntdsguid_for_computer(module, tmp_ctx,
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@@ -1510,6 +1524,7 @@ static int acl_modify(struct ldb_module *module, struct ldb_request *req)
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ret = acl_check_spn(tmp_ctx,
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module,
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req,
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+ el,
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sd,
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sid,
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attr,
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--
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2.23.0
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