From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753805Ab2GWBqM (ORCPT ); Sun, 22 Jul 2012 21:46:12 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:54504 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753632Ab2GWBnw (ORCPT ); Sun, 22 Jul 2012 21:43:52 -0400 Message-Id: <20120723010654.562849488@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Mon, 23 Jul 2012 02:07:11 +0100 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Jason Wang , "Michael S. Tsirkin" Subject: [ 020/108] macvtap: zerocopy: validate vectors before building skb In-Reply-To: <20120723010651.408577075@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:21c:bfff:fe03:f805 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jason Wang commit b92946e2919134ebe2a4083e4302236295ea2a73 upstream. There're several reasons that the vectors need to be validated: - Return error when caller provides vectors whose num is greater than UIO_MAXIOV. - Linearize part of skb when userspace provides vectors grater than MAX_SKB_FRAGS. - Return error when userspace provides vectors whose total length may exceed - MAX_SKB_FRAGS * PAGE_SIZE. Signed-off-by: Jason Wang Signed-off-by: Michael S. Tsirkin Signed-off-by: Ben Hutchings --- drivers/net/macvtap.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index a4ff694..163559c 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -529,9 +529,10 @@ static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from, } base = (unsigned long)from->iov_base + offset; size = ((base & ~PAGE_MASK) + len + ~PAGE_MASK) >> PAGE_SHIFT; + if (i + size > MAX_SKB_FRAGS) + return -EMSGSIZE; num_pages = get_user_pages_fast(base, size, 0, &page[i]); - if ((num_pages != size) || - (num_pages > MAX_SKB_FRAGS - skb_shinfo(skb)->nr_frags)) { + if (num_pages != size) { for (i = 0; i < num_pages; i++) put_page(page[i]); return -EFAULT; @@ -651,7 +652,7 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m, int err; struct virtio_net_hdr vnet_hdr = { 0 }; int vnet_hdr_len = 0; - int copylen; + int copylen = 0; bool zerocopy = false; if (q->flags & IFF_VNET_HDR) { @@ -680,15 +681,31 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m, if (unlikely(len < ETH_HLEN)) goto err; + err = -EMSGSIZE; + if (unlikely(count > UIO_MAXIOV)) + goto err; + if (m && m->msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) zerocopy = true; if (zerocopy) { + /* Userspace may produce vectors with count greater than + * MAX_SKB_FRAGS, so we need to linearize parts of the skb + * to let the rest of data to be fit in the frags. + */ + if (count > MAX_SKB_FRAGS) { + copylen = iov_length(iv, count - MAX_SKB_FRAGS); + if (copylen < vnet_hdr_len) + copylen = 0; + else + copylen -= vnet_hdr_len; + } /* There are 256 bytes to be copied in skb, so there is enough * room for skb expand head in case it is used. * The rest buffer is mapped from userspace. */ - copylen = vnet_hdr.hdr_len; + if (copylen < vnet_hdr.hdr_len) + copylen = vnet_hdr.hdr_len; if (!copylen) copylen = GOODCOPY_LEN; } else