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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AF5A8C7EE24 for ; Mon, 15 May 2023 18:01:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243467AbjEOSBg (ORCPT ); Mon, 15 May 2023 14:01:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60866 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244644AbjEOSBD (ORCPT ); Mon, 15 May 2023 14:01:03 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 04786176E8 for ; Mon, 15 May 2023 10:58:35 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id CC2AF62FF1 for ; Mon, 15 May 2023 17:58:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BF45AC433EF; Mon, 15 May 2023 17:58:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1684173497; bh=L2IQcPru72VQXbXFyuCIOIYDVg6DgV2qHXjBuNdA6fI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ju+uf2IDhv9bceuzRDKj9qFDrHgtSD5AFpwFP6Uy4XsK3dhnv0weoP1dEnad/SAU9 XNuCik+fdKl4jifagrZWjOWgHW9ohw8Sca1UU8RUw7tub4jmbf0vMMvBS122RHyvKs ZCWmjdojRYe3dP6GVZHOLUy5Yv8/XFPf95JwUPwQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Brad Spencer , Kuniyuki Iwashima , Johannes Berg , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.4 114/282] netlink: Use copy_to_user() for optval in netlink_getsockopt(). Date: Mon, 15 May 2023 18:28:12 +0200 Message-Id: <20230515161725.660629274@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230515161722.146344674@linuxfoundation.org> References: <20230515161722.146344674@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Kuniyuki Iwashima [ Upstream commit d913d32cc2707e9cd24fe6fa6d7d470e9c728980 ] Brad Spencer provided a detailed report [0] that when calling getsockopt() for AF_NETLINK, some SOL_NETLINK options set only 1 byte even though such options require at least sizeof(int) as length. The options return a flag value that fits into 1 byte, but such behaviour confuses users who do not initialise the variable before calling getsockopt() and do not strictly check the returned value as char. Currently, netlink_getsockopt() uses put_user() to copy data to optlen and optval, but put_user() casts the data based on the pointer, char *optval. As a result, only 1 byte is set to optval. To avoid this behaviour, we need to use copy_to_user() or cast optval for put_user(). Note that this changes the behaviour on big-endian systems, but we document that the size of optval is int in the man page. $ man 7 netlink ... Socket options To set or get a netlink socket option, call getsockopt(2) to read or setsockopt(2) to write the option with the option level argument set to SOL_NETLINK. Unless otherwise noted, optval is a pointer to an int. Fixes: 9a4595bc7e67 ("[NETLINK]: Add set/getsockopt options to support more than 32 groups") Fixes: be0c22a46cfb ("netlink: add NETLINK_BROADCAST_ERROR socket option") Fixes: 38938bfe3489 ("netlink: add NETLINK_NO_ENOBUFS socket flag") Fixes: 0a6a3a23ea6e ("netlink: add NETLINK_CAP_ACK socket option") Fixes: 2d4bc93368f5 ("netlink: extended ACK reporting") Fixes: 89d35528d17d ("netlink: Add new socket option to enable strict checking on dumps") Reported-by: Brad Spencer Link: https://lore.kernel.org/netdev/ZD7VkNWFfp22kTDt@datsun.rim.net/ Signed-off-by: Kuniyuki Iwashima Reviewed-by: Johannes Berg Link: https://lore.kernel.org/r/20230421185255.94606-1-kuniyu@amazon.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/netlink/af_netlink.c | 75 ++++++++++++---------------------------- 1 file changed, 23 insertions(+), 52 deletions(-) diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index a232fcbd721c4..00f040fb46b9c 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -1743,7 +1743,8 @@ static int netlink_getsockopt(struct socket *sock, int level, int optname, { struct sock *sk = sock->sk; struct netlink_sock *nlk = nlk_sk(sk); - int len, val, err; + unsigned int flag; + int len, val; if (level != SOL_NETLINK) return -ENOPROTOOPT; @@ -1755,39 +1756,17 @@ static int netlink_getsockopt(struct socket *sock, int level, int optname, switch (optname) { case NETLINK_PKTINFO: - if (len < sizeof(int)) - return -EINVAL; - len = sizeof(int); - val = nlk->flags & NETLINK_F_RECV_PKTINFO ? 1 : 0; - if (put_user(len, optlen) || - put_user(val, optval)) - return -EFAULT; - err = 0; + flag = NETLINK_F_RECV_PKTINFO; break; case NETLINK_BROADCAST_ERROR: - if (len < sizeof(int)) - return -EINVAL; - len = sizeof(int); - val = nlk->flags & NETLINK_F_BROADCAST_SEND_ERROR ? 1 : 0; - if (put_user(len, optlen) || - put_user(val, optval)) - return -EFAULT; - err = 0; + flag = NETLINK_F_BROADCAST_SEND_ERROR; break; case NETLINK_NO_ENOBUFS: - if (len < sizeof(int)) - return -EINVAL; - len = sizeof(int); - val = nlk->flags & NETLINK_F_RECV_NO_ENOBUFS ? 1 : 0; - if (put_user(len, optlen) || - put_user(val, optval)) - return -EFAULT; - err = 0; + flag = NETLINK_F_RECV_NO_ENOBUFS; break; case NETLINK_LIST_MEMBERSHIPS: { - int pos, idx, shift; + int pos, idx, shift, err = 0; - err = 0; netlink_lock_table(); for (pos = 0; pos * 8 < nlk->ngroups; pos += sizeof(u32)) { if (len - pos < sizeof(u32)) @@ -1804,40 +1783,32 @@ static int netlink_getsockopt(struct socket *sock, int level, int optname, if (put_user(ALIGN(nlk->ngroups / 8, sizeof(u32)), optlen)) err = -EFAULT; netlink_unlock_table(); - break; + return err; } case NETLINK_CAP_ACK: - if (len < sizeof(int)) - return -EINVAL; - len = sizeof(int); - val = nlk->flags & NETLINK_F_CAP_ACK ? 1 : 0; - if (put_user(len, optlen) || - put_user(val, optval)) - return -EFAULT; - err = 0; + flag = NETLINK_F_CAP_ACK; break; case NETLINK_EXT_ACK: - if (len < sizeof(int)) - return -EINVAL; - len = sizeof(int); - val = nlk->flags & NETLINK_F_EXT_ACK ? 1 : 0; - if (put_user(len, optlen) || put_user(val, optval)) - return -EFAULT; - err = 0; + flag = NETLINK_F_EXT_ACK; break; case NETLINK_GET_STRICT_CHK: - if (len < sizeof(int)) - return -EINVAL; - len = sizeof(int); - val = nlk->flags & NETLINK_F_STRICT_CHK ? 1 : 0; - if (put_user(len, optlen) || put_user(val, optval)) - return -EFAULT; - err = 0; + flag = NETLINK_F_STRICT_CHK; break; default: - err = -ENOPROTOOPT; + return -ENOPROTOOPT; } - return err; + + if (len < sizeof(int)) + return -EINVAL; + + len = sizeof(int); + val = nlk->flags & flag ? 1 : 0; + + if (put_user(len, optlen) || + copy_to_user(optval, &val, len)) + return -EFAULT; + + return 0; } static void netlink_cmsg_recv_pktinfo(struct msghdr *msg, struct sk_buff *skb) -- 2.39.2