From patchwork Tue Mar 28 14:40:55 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 13191171 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 E4D5EC77B62 for ; Tue, 28 Mar 2023 14:57:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233605AbjC1O5s (ORCPT ); Tue, 28 Mar 2023 10:57:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33418 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233607AbjC1O5r (ORCPT ); Tue, 28 Mar 2023 10:57:47 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E4914E054; Tue, 28 Mar 2023 07:57:45 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 7DFCFB81D75; Tue, 28 Mar 2023 14:57:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B85D2C433D2; Tue, 28 Mar 2023 14:57:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1680015464; bh=4Y8/xJhwU7aJXJUzYvMwx8jzSFFEXA9tPwndwM5aX+Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yQDX/C51XOYwN1TMB5U+LmIiDMk2MI3UD1a/XeM/DfY020HJ/EyZHuyvFlz0p4WJN gmwv12xLeuY6gBeAdqmnNtWoHQKdnysdS6rUluHlD39E6bRajgF40i2NjIkGWGWjXs VxvcnADrJyw/FJFY16o6zRbxRn7e4iOiBCj7E5Yo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Bharath SM , David Howells , Jarkko Sakkinen , Shyam Prasad N , Steve French , keyrings@vger.kernel.org, linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Sasha Levin Subject: [PATCH 6.1 059/224] keys: Do not cache key in task struct if key is requested from kernel thread Date: Tue, 28 Mar 2023 16:40:55 +0200 Message-Id: <20230328142619.827206364@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230328142617.205414124@linuxfoundation.org> References: <20230328142617.205414124@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org From: David Howells [ Upstream commit 47f9e4c924025c5be87959d3335e66fcbb7f6b5c ] The key which gets cached in task structure from a kernel thread does not get invalidated even after expiry. Due to which, a new key request from kernel thread will be served with the cached key if it's present in task struct irrespective of the key validity. The change is to not cache key in task_struct when key requested from kernel thread so that kernel thread gets a valid key on every key request. The problem has been seen with the cifs module doing DNS lookups from a kernel thread and the results getting pinned by being attached to that kernel thread's cache - and thus not something that can be easily got rid of. The cache would ordinarily be cleared by notify-resume, but kernel threads don't do that. This isn't seen with AFS because AFS is doing request_key() within the kernel half of a user thread - which will do notify-resume. Fixes: 7743c48e54ee ("keys: Cache result of request_key*() temporarily in task_struct") Signed-off-by: Bharath SM Signed-off-by: David Howells Reviewed-by: Jarkko Sakkinen cc: Shyam Prasad N cc: Steve French cc: keyrings@vger.kernel.org cc: linux-cifs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/CAGypqWw951d=zYRbdgNR4snUDvJhWL=q3=WOyh7HhSJupjz2vA@mail.gmail.com/ Signed-off-by: Sasha Levin --- security/keys/request_key.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/security/keys/request_key.c b/security/keys/request_key.c index 2da4404276f0f..07a0ef2baacd8 100644 --- a/security/keys/request_key.c +++ b/security/keys/request_key.c @@ -38,9 +38,12 @@ static void cache_requested_key(struct key *key) #ifdef CONFIG_KEYS_REQUEST_CACHE struct task_struct *t = current; - key_put(t->cached_requested_key); - t->cached_requested_key = key_get(key); - set_tsk_thread_flag(t, TIF_NOTIFY_RESUME); + /* Do not cache key if it is a kernel thread */ + if (!(t->flags & PF_KTHREAD)) { + key_put(t->cached_requested_key); + t->cached_requested_key = key_get(key); + set_tsk_thread_flag(t, TIF_NOTIFY_RESUME); + } #endif }