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=-18.8 required=3.0 tests=BAYES_00,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=ham 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 98D83C4338F for ; Wed, 28 Jul 2021 13:47:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 81C3960F9B for ; Wed, 28 Jul 2021 13:47:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236662AbhG1Nru (ORCPT ); Wed, 28 Jul 2021 09:47:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56908 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236316AbhG1NrI (ORCPT ); Wed, 28 Jul 2021 09:47:08 -0400 Received: from mail-lj1-x22c.google.com (mail-lj1-x22c.google.com [IPv6:2a00:1450:4864:20::22c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8D2DFC061384 for ; Wed, 28 Jul 2021 06:46:44 -0700 (PDT) Received: by mail-lj1-x22c.google.com with SMTP id q2so3157653ljq.5 for ; Wed, 28 Jul 2021 06:46:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rasmusvillemoes.dk; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=SbWIYXYlrIPDpsel0NzGQa0M/lKslwVGPnq1gOvws3s=; b=O+3cJ5Ny3Jt5pm3gKn6uFapk06ecZ8zmNJJFkasy6gvYmV+/PvmCc1EWKbi47JA4wM iI07bBX2++Uks7vTfNMXJZoXQEb2GBTWyR87oodpuyLh9jFjkRb1pzXJhHbQ8X843pV3 zT/aYQ248Wy5t/D5obB9CytgSfYQWf//T61JM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=SbWIYXYlrIPDpsel0NzGQa0M/lKslwVGPnq1gOvws3s=; b=K6kHgJXjQQbbagSNW7GESZLAhQlkhq0oz+oAoQ20tpd0EEs2FKreFBgcH+oAPtQhuh FNp7KuEmjYGn9qV43L9xqTClrpJPwQoZNyZvHylSfBqC8mwnLJtr2K03WengoB0rPR3Q SOGHu4GVeCb6UYjGKDyB1e5IKtWbNEiwJToTea+8cWeJmh6bholik1ZrRWZLejD3jaMB Q1bF+LGAuwMGY///0Jr47eztnJkEXnxGAZ87891GLXzgnB/QdOGqUc6y1ebFt5TsLWNI 5nZFcJH0G9qMoW+4znij5WCbhKHgNGGZ+x83E6uD1kOVvQPzw4Wbgukb5pDB750lWSge N2qg== X-Gm-Message-State: AOAM530OfOphgfr6vpm1AEAUh2kg3qNcRVgOXB/LfmOst9TNiartUfvC mvaZEfWdJloC3F8jFrjJOdnMSg== X-Google-Smtp-Source: ABdhPJwQYbSnMyafZuFr56LBbsjZEKxOPiGV0sH9yHwQ9Mx0aBeLbbpNtiwIWEO3aFIywmWGnaMvEQ== X-Received: by 2002:a2e:934f:: with SMTP id m15mr18513447ljh.208.1627480002943; Wed, 28 Jul 2021 06:46:42 -0700 (PDT) Received: from prevas-ravi.prevas.se ([81.216.59.226]) by smtp.gmail.com with ESMTPSA id q10sm8624lfm.5.2021.07.28.06.46.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Jul 2021 06:46:42 -0700 (PDT) From: Rasmus Villemoes To: Andrew Morton , Rasmus Villemoes , Luis Chamberlain Cc: torvalds@linux-foundation.org, Alexander Egorenkov , Bruno Goncalves , Heiner Kallweit , linux-kernel@vger.kernel.org Subject: [PATCH] init: move usermodehelper_enable() to populate_rootfs() Date: Wed, 28 Jul 2021 15:46:37 +0200 Message-Id: <20210728134638.329060-1-linux@rasmusvillemoes.dk> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, usermodehelper is enabled right before PID1 starts going through the initcalls. However, any call of a usermodehelper from a pure_, core_, postcore_, arch_, subsys_ or fs_ initcall is futile, as there is no filesystem contents yet. Up until commit e7cb072eb988 ("init/initramfs.c: do unpacking asynchronously"), such calls, whether via some request_module(), a legacy uevent "/sbin/hotplug" notification or something else, would just fail silently with (presumably) -ENOENT from kernel_execve(). However, that commit introduced the wait_for_initramfs() synchronization hook which must be called from the usermodehelper exec path right before the kernel_execve, in order that request_module() et al done from *after* rootfs_initcall() time (i.e. device_ and late_ initcalls) would continue to find a populated initramfs as they used to. Any call of wait_for_initramfs() done before the unpacking has been scheduled (i.e. before rootfs_initcall time) must just return immediately [and let the caller find an empty file system] in order not to deadlock the machine. I mistakenly thought, and my limited testing confirmed, that there were no such calls, so I added a pr_warn_once() in wait_for_initramfs(). It turns out that one can indeed hit request_module() as well as kobject_uevent_env() during those early init calls, leading to a user-visible warning in the kernel log emitted consistently for certain configurations. We could just remove the pr_warn_once(), but I think it's better to postpone enabling the usermodehelper framework until there is at least some chance of finding the executable. That is also a little more efficient in that a lot of work done in umh.c will be elided. However, it does change the error seen by those early callers from -ENOENT to -EBUSY, so there is a risk of a regression if any caller care about the exact error value. Reported-by: Alexander Egorenkov Reported-by: Bruno Goncalves Reported-by: Heiner Kallweit Fixes: e7cb072eb988 ("init/initramfs.c: do unpacking asynchronously") Signed-off-by: Rasmus Villemoes --- init/initramfs.c | 2 ++ init/main.c | 1 - init/noinitramfs.c | 2 ++ 3 files changed, 4 insertions(+), 1 deletion(-) diff --git a/init/initramfs.c b/init/initramfs.c index af27abc59643..a842c0544745 100644 --- a/init/initramfs.c +++ b/init/initramfs.c @@ -15,6 +15,7 @@ #include #include #include +#include static ssize_t __init xwrite(struct file *file, const char *p, size_t count, loff_t *pos) @@ -727,6 +728,7 @@ static int __init populate_rootfs(void) { initramfs_cookie = async_schedule_domain(do_populate_rootfs, NULL, &initramfs_domain); + usermodehelper_enable(); if (!initramfs_async) wait_for_initramfs(); return 0; diff --git a/init/main.c b/init/main.c index f5b8246e8aa1..d5c5542fe142 100644 --- a/init/main.c +++ b/init/main.c @@ -1387,7 +1387,6 @@ static void __init do_basic_setup(void) driver_init(); init_irq_proc(); do_ctors(); - usermodehelper_enable(); do_initcalls(); } diff --git a/init/noinitramfs.c b/init/noinitramfs.c index 3d62b07f3bb9..d1d26b93d25c 100644 --- a/init/noinitramfs.c +++ b/init/noinitramfs.c @@ -10,6 +10,7 @@ #include #include #include +#include /* * Create a simple rootfs that is similar to the default initramfs @@ -18,6 +19,7 @@ static int __init default_rootfs(void) { int err; + usermodehelper_enable(); err = init_mkdir("/dev", 0755); if (err < 0) goto out; -- 2.31.1