From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B5FE4C41513 for ; Sun, 13 Aug 2023 16:24:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231959AbjHMQX5 (ORCPT ); Sun, 13 Aug 2023 12:23:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48930 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233648AbjHMQXd (ORCPT ); Sun, 13 Aug 2023 12:23:33 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C706C1FD9; Sun, 13 Aug 2023 09:14:21 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 25A4663C0A; Sun, 13 Aug 2023 16:13:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CFA34C433C9; Sun, 13 Aug 2023 16:13:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1691943191; bh=CR2SSSmj6nOlFJfAO7XRG8O83A8MQtaAU8AR9iFYMUc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Q/QjKi18FBsI74q2XpJMhmwVU2eXBnn+0yyFD2eFu4H08+1GvcBhewHb5wZFiJXrl 3KuipkzX0F2XCY1704kpd8ZMA0Dp/wOA8X4QNXtPfTruLukQN+ovBnRftPIDtQ+Awh kJ9x7+0lgfbXYTV2t51HgOBfElMmrrHO67+KXdV9M5Be2KqGmlkALzm9SP8SQP2H1T 0kZEWwHPB6/zezg+LVEN5i61P46iM0dZTRCMG2un7jmD4lXD0LJvkPaIXM+fbYXr9R RG8mCTOHEdN9TIQCSYZpkj/2h6aLm2N8VJmZmTuScaNOiq4VE9n/NAgJEIgxqxZ0Fj KhpZoLBhAqkog== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: =?UTF-8?q?Christian=20G=C3=B6ttsche?= , Jarkko Sakkinen , Sasha Levin , dhowells@redhat.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, keyrings@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 14/14] security: keys: perform capable check only on privileged operations Date: Sun, 13 Aug 2023 12:12:02 -0400 Message-Id: <20230813161202.1086004-14-sashal@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230813161202.1086004-1-sashal@kernel.org> References: <20230813161202.1086004-1-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.4.253 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Christian Göttsche [ Upstream commit 2d7f105edbb3b2be5ffa4d833abbf9b6965e9ce7 ] If the current task fails the check for the queried capability via `capable(CAP_SYS_ADMIN)` LSMs like SELinux generate a denial message. Issuing such denial messages unnecessarily can lead to a policy author granting more privileges to a subject than needed to silence them. Reorder CAP_SYS_ADMIN checks after the check whether the operation is actually privileged. Signed-off-by: Christian Göttsche Reviewed-by: Jarkko Sakkinen Signed-off-by: Jarkko Sakkinen Signed-off-by: Sasha Levin --- security/keys/keyctl.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index edde63a63007f..f42968f349584 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -977,14 +977,19 @@ long keyctl_chown_key(key_serial_t id, uid_t user, gid_t group) ret = -EACCES; down_write(&key->sem); - if (!capable(CAP_SYS_ADMIN)) { + { + bool is_privileged_op = false; + /* only the sysadmin can chown a key to some other UID */ if (user != (uid_t) -1 && !uid_eq(key->uid, uid)) - goto error_put; + is_privileged_op = true; /* only the sysadmin can set the key's GID to a group other * than one of those that the current process subscribes to */ if (group != (gid_t) -1 && !gid_eq(gid, key->gid) && !in_group_p(gid)) + is_privileged_op = true; + + if (is_privileged_op && !capable(CAP_SYS_ADMIN)) goto error_put; } @@ -1084,7 +1089,7 @@ long keyctl_setperm_key(key_serial_t id, key_perm_t perm) down_write(&key->sem); /* if we're not the sysadmin, we can only change a key that we own */ - if (capable(CAP_SYS_ADMIN) || uid_eq(key->uid, current_fsuid())) { + if (uid_eq(key->uid, current_fsuid()) || capable(CAP_SYS_ADMIN)) { key->perm = perm; ret = 0; } -- 2.40.1