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 X-Spam-Level: X-Spam-Status: No, score=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 69362C47082 for ; Mon, 31 May 2021 16:15:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3D15D61370 for ; Mon, 31 May 2021 16:15:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233634AbhEaQQ1 (ORCPT ); Mon, 31 May 2021 12:16:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:38038 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234203AbhEaOji (ORCPT ); Mon, 31 May 2021 10:39:38 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8D3A861874; Mon, 31 May 2021 13:52:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1622469180; bh=MOa681YkjIDTsO/iqmYvJ5GkdkdHKU8MnIisXx/mwyk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dRM631/JslK+IvKRdjzCphN5XeIY5uoNPg1lRMok7+9SSm6RICPHM9R9qaTHxv6Mb WGAYnJgcVvQ8nrvBJgsDOULU6x2sAYiQ9wQUcyW5irRVkfW5jtV8zUXpvi+oYx5YLu bh60btuX4/chW6e//0VUAd5PUvalByqia7jvrJ8k= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sargun Dhillon , Tycho Andersen , Christian Brauner , Kees Cook , Rodrigo Campos Subject: [PATCH 5.12 064/296] seccomp: Refactor notification handler to prepare for new semantics Date: Mon, 31 May 2021 15:11:59 +0200 Message-Id: <20210531130705.991657084@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210531130703.762129381@linuxfoundation.org> References: <20210531130703.762129381@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sargun Dhillon commit ddc473916955f7710d1eb17c1273d91c8622a9fe upstream. This refactors the user notification code to have a do / while loop around the completion condition. This has a small change in semantic, in that previously we ignored addfd calls upon wakeup if the notification had been responded to, but instead with the new change we check for an outstanding addfd calls prior to returning to userspace. Rodrigo Campos also identified a bug that can result in addfd causing an early return, when the supervisor didn't actually handle the syscall [1]. [1]: https://lore.kernel.org/lkml/20210413160151.3301-1-rodrigo@kinvolk.io/ Fixes: 7cf97b125455 ("seccomp: Introduce addfd ioctl to seccomp user notifier") Signed-off-by: Sargun Dhillon Acked-by: Tycho Andersen Acked-by: Christian Brauner Signed-off-by: Kees Cook Tested-by: Rodrigo Campos Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20210517193908.3113-3-sargun@sargun.me Signed-off-by: Greg Kroah-Hartman --- kernel/seccomp.c | 30 ++++++++++++++++-------------- 1 file changed, 16 insertions(+), 14 deletions(-) --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -1098,28 +1098,30 @@ static int seccomp_do_user_notification( up(&match->notif->request); wake_up_poll(&match->wqh, EPOLLIN | EPOLLRDNORM); - mutex_unlock(&match->notify_lock); /* * This is where we wait for a reply from userspace. */ -wait: - err = wait_for_completion_interruptible(&n.ready); - mutex_lock(&match->notify_lock); - if (err == 0) { - /* Check if we were woken up by a addfd message */ + do { + mutex_unlock(&match->notify_lock); + err = wait_for_completion_interruptible(&n.ready); + mutex_lock(&match->notify_lock); + if (err != 0) + goto interrupted; + addfd = list_first_entry_or_null(&n.addfd, struct seccomp_kaddfd, list); - if (addfd && n.state != SECCOMP_NOTIFY_REPLIED) { + /* Check if we were woken up by a addfd message */ + if (addfd) seccomp_handle_addfd(addfd); - mutex_unlock(&match->notify_lock); - goto wait; - } - ret = n.val; - err = n.error; - flags = n.flags; - } + } while (n.state != SECCOMP_NOTIFY_REPLIED); + + ret = n.val; + err = n.error; + flags = n.flags; + +interrupted: /* If there were any pending addfd calls, clear them out */ list_for_each_entry_safe(addfd, tmp, &n.addfd, list) { /* The process went away before we got a chance to handle it */