CVE-2013-4496:samr: Remove ChangePasswordUser

This old password change mechanism does not provide the plaintext to
validate against password complexity, and it is not used by modern
clients.  It also has quite difficult semantics to handle regarding
password lockout.

The missing features in both implementations (by design) were:

 - the password complexity checks (no plaintext)
 - the minimum password length (no plaintext)

Additionally, the source3 version did not check:

 - the minimum password age
 - pdb_get_pass_can_change() which checks the security
   descriptor for the 'user cannot change password' setting.
 - the password history
 - the output of the 'passwd program' if 'unix passwd sync = yes'.

Finally, the mechanism was almost useless, as it was incorrectly
only made available to administrative users with permission
to reset the password.  It is removed here so that it is not
mistakenly reinstated in the future.

Andrew Bartlett

Bug: https://bugzilla.samba.org/show_bug.cgi?id=10245

Change-Id: If2edd3183c177e5ff37c9511b0d0ad0dd9038c66
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Reviewed-on: https://gerrit.samba.org/37

1 files changed, 6 insertions, 139 deletions

diff --git a/source4/rpc_server/samr/samr_password.c b/source4/rpc_server/samr/samr_password.c
index 2d9c48abd74..9d6c9212f47 100644
--- a/source4/rpc_server/samr/samr_password.c
+++ b/source4/rpc_server/samr/samr_password.c
@@ -33,150 +33,17 @@
 
 /*
   samr_ChangePasswordUser
+
+  So old it is just not worth implementing
+  because it does not supply a plaintext and so we can't do password
+  complexity checking and cannot update all the other password hashes.
+
 */
 NTSTATUS dcesrv_samr_ChangePasswordUser(struct dcesrv_call_state *dce_call,
 					TALLOC_CTX *mem_ctx,
 					struct samr_ChangePasswordUser *r)
 {
-	struct dcesrv_handle *h;
-	struct samr_account_state *a_state;
-	struct ldb_context *sam_ctx;
-	struct ldb_message **res;
-	int ret;
-	struct samr_Password new_lmPwdHash, new_ntPwdHash, checkHash;
-	struct samr_Password *lm_pwd, *nt_pwd;
-	NTSTATUS status = NT_STATUS_OK;
-	const char * const attrs[] = { "dBCSPwd", "unicodePwd" , NULL };
-
-	DCESRV_PULL_HANDLE(h, r->in.user_handle, SAMR_HANDLE_USER);
-
-	a_state = h->data;
-
-	/* basic sanity checking on parameters.  Do this before any database ops */
-	if (!r->in.lm_present || !r->in.nt_present ||
-	    !r->in.old_lm_crypted || !r->in.new_lm_crypted ||
-	    !r->in.old_nt_crypted || !r->in.new_nt_crypted) {
-		/* we should really handle a change with lm not
-		   present */
-		return NT_STATUS_INVALID_PARAMETER_MIX;
-	}
-
-	/* Connect to a SAMDB with system privileges for fetching the old pw
-	 * hashes. */
-	sam_ctx = samdb_connect(mem_ctx, dce_call->event_ctx,
-				dce_call->conn->dce_ctx->lp_ctx,
-				system_session(dce_call->conn->dce_ctx->lp_ctx), 0);
-	if (sam_ctx == NULL) {
-		return NT_STATUS_INVALID_SYSTEM_SERVICE;
-	}
-
-	/* fetch the old hashes */
-	ret = gendb_search_dn(sam_ctx, mem_ctx,
-			      a_state->account_dn, &res, attrs);
-	if (ret != 1) {
-		return NT_STATUS_WRONG_PASSWORD;
-	}
-
-	status = samdb_result_passwords(mem_ctx,
-					dce_call->conn->dce_ctx->lp_ctx,
-					res[0], &lm_pwd, &nt_pwd);
-	if (!NT_STATUS_IS_OK(status) || !nt_pwd) {
-		return NT_STATUS_WRONG_PASSWORD;
-	}
-
-	/* decrypt and check the new lm hash */
-	if (lm_pwd) {
-		D_P16(lm_pwd->hash, r->in.new_lm_crypted->hash, new_lmPwdHash.hash);
-		D_P16(new_lmPwdHash.hash, r->in.old_lm_crypted->hash, checkHash.hash);
-	}
-
-	/* decrypt and check the new nt hash */
-	D_P16(nt_pwd->hash, r->in.new_nt_crypted->hash, new_ntPwdHash.hash);
-	D_P16(new_ntPwdHash.hash, r->in.old_nt_crypted->hash, checkHash.hash);
-
-	/* The NT Cross is not required by Win2k3 R2, but if present
-	   check the nt cross hash */
-	if (r->in.cross1_present && r->in.nt_cross && lm_pwd) {
-		D_P16(lm_pwd->hash, r->in.nt_cross->hash, checkHash.hash);
-	}
-
-	/* The LM Cross is not required by Win2k3 R2, but if present
-	   check the lm cross hash */
-	if (r->in.cross2_present && r->in.lm_cross && lm_pwd) {
-		D_P16(nt_pwd->hash, r->in.lm_cross->hash, checkHash.hash);
-	}
-
-	/* Start a SAM with user privileges for the password change */
-	sam_ctx = samdb_connect(mem_ctx, dce_call->event_ctx,
-				dce_call->conn->dce_ctx->lp_ctx,
-				dce_call->conn->auth_state.session_info, 0);
-	if (sam_ctx == NULL) {
-		return NT_STATUS_INVALID_SYSTEM_SERVICE;
-	}
-
-	/* Start transaction */
-	ret = ldb_transaction_start(sam_ctx);
-	if (ret != LDB_SUCCESS) {
-		DEBUG(1, ("Failed to start transaction: %s\n", ldb_errstring(sam_ctx)));
-		return NT_STATUS_TRANSACTION_ABORTED;
-	}
-
-	/* Performs the password modification. We pass the old hashes read out
-	 * from the database since they were already checked against the user-
-	 * provided ones. */
-	status = samdb_set_password(sam_ctx, mem_ctx,
-				    a_state->account_dn,
-				    a_state->domain_state->domain_dn,
-				    NULL, &new_lmPwdHash, &new_ntPwdHash,
-				    lm_pwd, nt_pwd, /* this is a user password change */
-				    NULL,
-				    NULL);
-	if (!NT_STATUS_IS_OK(status)) {
-		ldb_transaction_cancel(sam_ctx);
-		return status;
-	}
-
-	/* decrypt and check the new lm hash */
-	if (lm_pwd) {
-		if (memcmp(checkHash.hash, lm_pwd, 16) != 0) {
-			ldb_transaction_cancel(sam_ctx);
-			return NT_STATUS_WRONG_PASSWORD;
-		}
-	}
-
-	if (memcmp(checkHash.hash, nt_pwd, 16) != 0) {
-		ldb_transaction_cancel(sam_ctx);
-		return NT_STATUS_WRONG_PASSWORD;
-	}
-
-	/* The NT Cross is not required by Win2k3 R2, but if present
-	   check the nt cross hash */
-	if (r->in.cross1_present && r->in.nt_cross && lm_pwd) {
-		if (memcmp(checkHash.hash, new_ntPwdHash.hash, 16) != 0) {
-			ldb_transaction_cancel(sam_ctx);
-			return NT_STATUS_WRONG_PASSWORD;
-		}
-	}
-
-	/* The LM Cross is not required by Win2k3 R2, but if present
-	   check the lm cross hash */
-	if (r->in.cross2_present && r->in.lm_cross && lm_pwd) {
-		if (memcmp(checkHash.hash, new_lmPwdHash.hash, 16) != 0) {
-			ldb_transaction_cancel(sam_ctx);
-			return NT_STATUS_WRONG_PASSWORD;
-		}
-	}
-
-	/* And this confirms it in a transaction commit */
-	ret = ldb_transaction_commit(sam_ctx);
-	if (ret != LDB_SUCCESS) {
-		DEBUG(1,("Failed to commit transaction to change password on %s: %s\n",
-			 ldb_dn_get_linearized(a_state->account_dn),
-			 ldb_errstring(sam_ctx)));
-		return NT_STATUS_TRANSACTION_ABORTED;
-	}
-
-	return NT_STATUS_OK;
+	return NT_STATUS_NOT_IMPLEMENTED;
 }
 
 /*