From patchwork Wed Sep 6 12:04:59 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 13375623 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 70369EB8FAF for ; Wed, 6 Sep 2023 12:06:53 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qdrId-0004af-MC; Wed, 06 Sep 2023 08:06:23 -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 1qdrI3-0003tU-23 for qemu-devel@nongnu.org; Wed, 06 Sep 2023 08:05:49 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qdrHw-0006n6-Sc for qemu-devel@nongnu.org; Wed, 06 Sep 2023 08:05:44 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1694001934; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=DdMOYI+4FlfKF4vgHKGO2hvFnYmkybyspyiPalOlwqE=; b=H0JEOrLkTj3rzb5BKYLlMdf10AIoZlJC8S0BOmZWNnDTKauaMrbufiMMrZ6X0B1+1Fj6Gs mgMO4V/QvjtKD7LG5TuGEj4PnMTKSGHxnBpO5iUg2GbPl8K/hLdSAwR+UIyXud7w1pB/dR UHo/OcdBt4Rg6VzRa0N0ABnAlgwo1v4= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [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-175-Uqcnuo2CMGiSNL7NQEZhMA-1; Wed, 06 Sep 2023 08:05:33 -0400 X-MC-Unique: Uqcnuo2CMGiSNL7NQEZhMA-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 03B051C09CCE; Wed, 6 Sep 2023 12:05:33 +0000 (UTC) Received: from t14s.fritz.box (unknown [10.39.192.60]) by smtp.corp.redhat.com (Postfix) with ESMTP id 31614493110; Wed, 6 Sep 2023 12:05:30 +0000 (UTC) From: David Hildenbrand To: qemu-devel@nongnu.org Cc: David Hildenbrand , Paolo Bonzini , Peter Xu , Igor Mammedov , Thiner Logoer , =?utf-8?q?Philippe_Mathieu-Daud?= =?utf-8?q?=C3=A9?= , =?utf-8?q?Daniel_P_=2E_Berrang?= =?utf-8?q?=C3=A9?= , Stefan Hajnoczi , Elena Ufimtseva , Jagannathan Raman , "Michael S. Tsirkin" , Ani Sinha , Xiao Guangrong , Daniel Henrique Barboza , Greg Kurz , Eric Blake , Markus Armbruster , Eduardo Habkost Subject: [PATCH v4 07/11] softmmu/physmem: Never return directories from file_ram_open() Date: Wed, 6 Sep 2023 14:04:59 +0200 Message-ID: <20230906120503.359863-8-david@redhat.com> In-Reply-To: <20230906120503.359863-1-david@redhat.com> References: <20230906120503.359863-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 Received-SPF: pass client-ip=170.10.129.124; envelope-from=david@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 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org open() does not fail on directories when opening them readonly (O_RDONLY). Currently, we succeed opening such directories and fail later during mmap(), resulting in a misleading error message. $ ./qemu-system-x86_64 \ -object memory-backend-file,id=ram0,mem-path=tmp,readonly=true,size=1g qemu-system-x86_64: unable to map backing store for guest RAM: No such device To identify directories and handle them accordingly in file_ram_open() also when readonly=true was specified, detect if we just opened a directory using fstat() instead. Then, fail file_ram_open() right away, similarly to how we now fail if the file does not exist and we want to open the file readonly. With this change, we get a nicer error message: qemu-system-x86_64: can't open backing store tmp for guest RAM: Is a directory Note that the only memory-backend-file will end up calling memory_region_init_ram_from_file() -> qemu_ram_alloc_from_file() -> file_ram_open(). Reported-by: Thiner Logoer Reviewed-by: Peter Xu Signed-off-by: David Hildenbrand Tested-by: Mario Casquero --- softmmu/physmem.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/softmmu/physmem.c b/softmmu/physmem.c index 138402b6cf..f1cd3ec28a 100644 --- a/softmmu/physmem.c +++ b/softmmu/physmem.c @@ -1299,6 +1299,25 @@ static int file_ram_open(const char *path, for (;;) { fd = open(path, readonly ? O_RDONLY : O_RDWR); if (fd >= 0) { + /* + * open(O_RDONLY) won't fail with EISDIR. Check manually if we + * opened a directory and fail similarly to how we fail ENOENT + * in readonly mode. Note that mkstemp() would imply O_RDWR. + */ + if (readonly) { + struct stat file_stat; + + if (fstat(fd, &file_stat)) { + close(fd); + if (errno == EINTR) { + continue; + } + return -errno; + } else if (S_ISDIR(file_stat.st_mode)) { + close(fd); + return -EISDIR; + } + } /* @path names an existing file, use it */ break; }