From nobody Mon Feb 9 19:31:11 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 D6966C6FD18 for ; Wed, 29 Mar 2023 14:18:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231184AbjC2OSS (ORCPT ); Wed, 29 Mar 2023 10:18:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54660 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230491AbjC2ORS (ORCPT ); Wed, 29 Mar 2023 10:17:18 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1C81D4C3F for ; Wed, 29 Mar 2023 07:15:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1680099300; 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=DuSpRIzeQZ01nwpBuy8LkLTaj8h3sZ+W9+uqSPxJMKE=; b=Ikqa8NT+S3ldFr78WGnoKdiOQKW7zATeeRMFipjl8QjhCht1bqpTsyNlBFLiWK+6HvNOCt L4d2XaSZVPRIVEdixQB3IjvgViZ1906LAhAzIQYiMCZ9MIm6HtKxZpFe+Q1jg8TEGemang taDF6yWCz2rQaRPev8at8UfadMIw8ms= 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-306-jnNXOk_ROhmWbX02B6xDmA-1; Wed, 29 Mar 2023 10:14:55 -0400 X-MC-Unique: jnNXOk_ROhmWbX02B6xDmA-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 170BE85A5B1; Wed, 29 Mar 2023 14:14:54 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.18]) by smtp.corp.redhat.com (Postfix) with ESMTP id 35746492C3E; Wed, 29 Mar 2023 14:14:52 +0000 (UTC) From: David Howells To: Matthew Wilcox , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: David Howells , Al Viro , Christoph Hellwig , Jens Axboe , Jeff Layton , Christian Brauner , Chuck Lever III , Linus Torvalds , netdev@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH v2 20/48] af_unix: Make sendmsg(MSG_SPLICE_PAGES) copy unspliceable data Date: Wed, 29 Mar 2023 15:13:26 +0100 Message-Id: <20230329141354.516864-21-dhowells@redhat.com> In-Reply-To: <20230329141354.516864-1-dhowells@redhat.com> References: <20230329141354.516864-1-dhowells@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" If sendmsg() with MSG_SPLICE_PAGES encounters a page that shouldn't be spliced - a slab page, for instance, or one with a zero count - make unix_extract_bvec_to_skb() copy it. Signed-off-by: David Howells cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: Jens Axboe cc: Matthew Wilcox cc: netdev@vger.kernel.org --- net/unix/af_unix.c | 44 +++++++++++++++++++++++++++++++++----------- 1 file changed, 33 insertions(+), 11 deletions(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 84a0d97f1aa4..b4b27a652ef0 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -2154,12 +2154,12 @@ static int queue_oob(struct socket *sock, struct ms= ghdr *msg, struct sock *other /* * Extract pages from an iterator and add them to the socket buffer. */ -static ssize_t unix_extract_bvec_to_skb(struct sk_buff *skb, - struct iov_iter *iter, ssize_t maxsize) +static ssize_t unix_extract_bvec_to_skb(struct sk_buff *skb, struct iov_it= er *iter, + ssize_t maxsize, gfp_t gfp) { struct page *pages[8], **ppages =3D pages; unsigned int i, nr; - ssize_t ret =3D 0; + ssize_t spliced =3D 0, ret =3D 0; =20 while (iter->count > 0) { size_t off, len; @@ -2171,31 +2171,52 @@ static ssize_t unix_extract_bvec_to_skb(struct sk_b= uff *skb, =20 len =3D iov_iter_extract_pages(iter, &ppages, maxsize, nr, 0, &off); if (len <=3D 0) { - if (!ret) - ret =3D len ?: -EIO; + ret =3D len ?: -EIO; break; } =20 i =3D 0; do { + struct page *page =3D pages[i++]; size_t part =3D min(PAGE_SIZE - off, len); + bool put =3D false; + + if (!sendpage_ok(page)) { + const void *p =3D kmap_local_page(page); + void *q; + + q =3D page_frag_memdup(NULL, p + off, part, gfp, + ULONG_MAX); + kunmap_local(p); + if (!q) { + iov_iter_revert(iter, len); + ret =3D -ENOMEM; + goto out; + } + page =3D virt_to_page(q); + off =3D offset_in_page(q); + put =3D true; + } =20 - if (skb_append_pagefrags(skb, pages[i++], off, part) < 0) { - if (!ret) - ret =3D -EMSGSIZE; + ret =3D skb_append_pagefrags(skb, page, off, part); + if (put) + put_page(page); + if (ret < 0) { + iov_iter_revert(iter, len); goto out; } off =3D 0; - ret +=3D part; + spliced +=3D part; maxsize -=3D part; len -=3D part; } while (len > 0); + if (maxsize <=3D 0) break; } =20 out: - return ret; + return spliced ?: ret; } =20 static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg, @@ -2272,7 +2293,8 @@ static int unix_stream_sendmsg(struct socket *sock, s= truct msghdr *msg, fds_sent =3D true; =20 if (unlikely(msg->msg_flags & MSG_SPLICE_PAGES)) { - size =3D unix_extract_bvec_to_skb(skb, &msg->msg_iter, size); + size =3D unix_extract_bvec_to_skb(skb, &msg->msg_iter, size, + sk->sk_allocation); skb->data_len +=3D size; skb->len +=3D size; skb->truesize +=3D size;