From nobody Sun Feb 8 15:58:19 2026 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 23C99C7EE25 for ; Wed, 7 Jun 2023 14:32:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237823AbjFGOcA (ORCPT ); Wed, 7 Jun 2023 10:32:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56632 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241036AbjFGObF (ORCPT ); Wed, 7 Jun 2023 10:31:05 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6DDD010DE for ; Wed, 7 Jun 2023 07:30:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1686148217; 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=704Gul1es5vKB8f3fNlqLP0xfed1dEhsuWb+SLm3klg=; b=bn/qOzkApdQM/LWC9c1oeeDg0dgq6ElOFl4Di0rErVEsdObvHdvKaa9iA9TRtMLb7pDzpV StYMQY/GpcoOA9MGv1T1gMibxQUZS7Ktd4AUnJQDnZhrKPzsLXsc5sbBfY+QraGjf++hkD U6s6P6QqgSGbj9Z9jGZHrK+D9IgXwTc= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-635-TJH48CwcMEypUtBg4mC4JQ-1; Wed, 07 Jun 2023 10:06:10 -0400 X-MC-Unique: TJH48CwcMEypUtBg4mC4JQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E0D86800969; Wed, 7 Jun 2023 14:06:09 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.42.28.182]) by smtp.corp.redhat.com (Postfix) with ESMTP id EE97F2166B25; Wed, 7 Jun 2023 14:06:05 +0000 (UTC) From: David Howells To: netdev@vger.kernel.org, Linus Torvalds Cc: David Howells , Chuck Lever , Boris Pismenny , John Fastabend , Jakub Kicinski , "David S. Miller" , Eric Dumazet , Paolo Abeni , Willem de Bruijn , David Ahern , Matthew Wilcox , Jens Axboe , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH net-next v5 01/14] net: Block MSG_SENDPAGE_* from being passed to sendmsg() by userspace Date: Wed, 7 Jun 2023 15:05:46 +0100 Message-ID: <20230607140559.2263470-2-dhowells@redhat.com> In-Reply-To: <20230607140559.2263470-1-dhowells@redhat.com> References: <20230607140559.2263470-1-dhowells@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" It is necessary to allow MSG_SENDPAGE_* to be passed into ->sendmsg() to allow sendmsg(MSG_SPLICE_PAGES) to replace ->sendpage(). Unblocking them in the network protocol, however, allows these flags to be passed in by userspace too[1]. Fix this by marking MSG_SENDPAGE_NOPOLICY, MSG_SENDPAGE_NOTLAST and MSG_SENDPAGE_DECRYPTED as internal flags, which causes sendmsg() to object if they are passed to sendmsg() by userspace. Network protocol ->sendmsg() implementations can then allow them through. Note that it should be possible to remove MSG_SENDPAGE_NOTLAST once sendpage is removed as a whole slew of pages will be passed in in one go by splice through sendmsg, with MSG_MORE being set if it has more data waiting in the pipe. Signed-off-by: David Howells cc: Jakub Kicinski cc: Chuck Lever cc: Boris Pismenny cc: John Fastabend cc: Eric Dumazet cc: "David S. Miller" cc: Paolo Abeni cc: Jens Axboe cc: Matthew Wilcox cc: netdev@vger.kernel.org Link: https://lore.kernel.org/r/20230526181338.03a99016@kernel.org/ [1] --- include/linux/socket.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/include/linux/socket.h b/include/linux/socket.h index bd1cc3238851..3fd3436bc09f 100644 --- a/include/linux/socket.h +++ b/include/linux/socket.h @@ -339,7 +339,9 @@ struct ucred { #endif =20 /* Flags to be cleared on entry by sendmsg and sendmmsg syscalls */ -#define MSG_INTERNAL_SENDMSG_FLAGS (MSG_SPLICE_PAGES) +#define MSG_INTERNAL_SENDMSG_FLAGS \ + (MSG_SPLICE_PAGES | MSG_SENDPAGE_NOPOLICY | MSG_SENDPAGE_NOTLAST | \ + MSG_SENDPAGE_DECRYPTED) =20 /* Setsockoptions(2) level. Thanks to BSD these must match IPPROTO_xxx */ #define SOL_IP 0