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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2A1F3C04A94 for ; Tue, 1 Aug 2023 21:28:09 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qQwtf-0006Bt-VV; Tue, 01 Aug 2023 17:27:16 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qQwte-0006Bg-MB for qemu-devel@nongnu.org; Tue, 01 Aug 2023 17:27:14 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qQwtc-0005o9-W9 for qemu-devel@nongnu.org; Tue, 01 Aug 2023 17:27:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1690925232; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=qWpzn6EDfV3epZYHPu3ZWiKxJPJcv6XZsVNadt1LM98=; b=JkERyqePstRYoch4Qhef9WfC90+exuqH1f4ykWsx/Ghe69KuqD87zTYBbDOnaTQvuniuqB NdfndXXarnfJMOJ/xMnvTUnHyyEfGsX6SSXfbX3ZMA3suh/tqgDrqGTbNq2rLSPLNHt5KL RE8bBnqkcUeenF0oM2pYk68l1DZ9rD8= Received: from mimecast-mx02.redhat.com (66.187.233.73 [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-108-e9nC9lpSP2Ctlxo3K2P79w-1; Tue, 01 Aug 2023 17:27:07 -0400 X-MC-Unique: e9nC9lpSP2Ctlxo3K2P79w-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id AA9461C05134; Tue, 1 Aug 2023 21:27:06 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.93]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B7C0FC57963; Tue, 1 Aug 2023 21:27:05 +0000 (UTC) Date: Tue, 1 Aug 2023 22:27:03 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Helge Deller Cc: qemu-devel@nongnu.org, Peter Maydell , Richard Henderson , Laurent Vivier , qemu-arm@nongnu.org Subject: Re: [PATCH 1/2] linux-user: Fix openat() emulation to correctly detect accesses to /proc Message-ID: References: <20230801191035.374120-1-deller@gmx.de> <20230801191035.374120-2-deller@gmx.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20230801191035.374120-2-deller@gmx.de> User-Agent: Mutt/2.2.9 (2022-11-12) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Tue, Aug 01, 2023 at 09:10:34PM +0200, Helge Deller wrote: > In qemu we catch accesses to files like /proc/cpuinfo or /proc/net/route > and return to the guest contents which would be visible on a real system > (instead what the host would show). > > This patch fixes a bug, where for example the accesses > cat /proc////cpuinfo > or > cd /proc && cat cpuinfo > will not be recognized by qemu and where qemu will wrongly show > the contents of the host's /proc/cpuinfo file. > > Signed-off-by: Helge Deller > > -- > v2: > - use g_autofree instead of pathname on stack > Daniel P. Berrangé requested to not put buffers on stack. > Using g_autofree keeps code much cleaner than using > extended semantics of realpath(), unless I can use g_autofree > on malloced area from realpath(). g_autofree is backed by free(), so it is fine to use that with the realpath() allocated buffer. > --- > linux-user/syscall.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/linux-user/syscall.c b/linux-user/syscall.c > index 95727a816a..a089463969 100644 > --- a/linux-user/syscall.c > +++ b/linux-user/syscall.c > @@ -8539,9 +8539,12 @@ static int open_hardware(CPUArchState *cpu_env, int fd) > } > #endif > > -int do_guest_openat(CPUArchState *cpu_env, int dirfd, const char *pathname, > + > +int do_guest_openat(CPUArchState *cpu_env, int dirfd, const char *fname, > int flags, mode_t mode, bool safe) > { > + g_autofree char *proc_name = g_new(char, PATH_MAX); > + const char *pathname; > struct fake_open { > const char *filename; > int (*fill)(CPUArchState *cpu_env, int fd); > @@ -8567,6 +8570,13 @@ int do_guest_openat(CPUArchState *cpu_env, int dirfd, const char *pathname, > { NULL, NULL, NULL } > }; > > + /* if this is a file from /proc/ filesystem, expand full name */ > + if (realpath(fname, proc_name) && strncmp(proc_name, "/proc/", 6) == 0) { > + pathname = proc_name; > + } else { > + pathname = fname; > + } > + > if (is_proc_myself(pathname, "exe")) { > if (safe) { > return safe_openat(dirfd, exec_path, flags, mode); > -- > 2.41.0 > With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|