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 3137CC433F5 for ; Thu, 29 Sep 2022 14:28:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234788AbiI2O2Q (ORCPT ); Thu, 29 Sep 2022 10:28:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33878 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235090AbiI2O2O (ORCPT ); Thu, 29 Sep 2022 10:28:14 -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 55559264AE for ; Thu, 29 Sep 2022 07:28:13 -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 AD800614CB for ; Thu, 29 Sep 2022 14:28:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6E612C433D6; Thu, 29 Sep 2022 14:28:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1664461692; bh=m2SH8gapNTTrvDnhtok6rkUjsEZOEUUIVln/Dxwh7t4=; h=From:To:Cc:Subject:Date:From; b=VOUUC/+2L/ha087TkNK7JjOZ7Kyh3Oz1n9CsAvQSo8BLVhXDfx5PceEZMGSqozdBI wZAEWozesDZhZ0hrrwY4f673imC6Z9HnO9LAZn9rYs4vHC/eHAid11M3h+Gk4RorwH H/jLAq7CcM2YF1ujplhoIUh7wyfWSnRa93lcHqHhiosNBGorHmapbYRsP6cFh/Cox6 F0mG9DvFRwrF9Dkx+dgDvkTOIbfPWBXp+dsA7ocMidHmWP13kN8H6AwRB1U9tZdAoP ClZXFtPM9p83ErUHrJGSI9G5ACEIOLvJ3SvHqiMFawHvESZR0wYsA2wCA/jjUDIoIC kb/KqiLXSIEqw== From: Jakub Kicinski To: davem@davemloft.net Cc: netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, Jakub Kicinski , Johannes Berg , Nikolay Aleksandrov , Nicolas Dichtel , Guillaume Nault , Florent Fourcot , Pablo Neira Ayuso , Florian Westphal , Jamal Hadi Salim , Jacob Keller , Hangbin Liu Subject: [PATCH net-next RESEND] genetlink: reject use of nlmsg_flags for new commands Date: Thu, 29 Sep 2022 07:28:09 -0700 Message-Id: <20220929142809.1167546-1-kuba@kernel.org> X-Mailer: git-send-email 2.37.3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Commit 9c5d03d36251 ("genetlink: start to validate reserved header bytes") introduced extra validation for genetlink headers. We had to gate it to only apply to new commands, to maintain bug-wards compatibility. Use this opportunity (before the new checks make it to Linus's tree) to add more conditions. Validate that Generic Netlink families do not use nlmsg_flags outside of the well-understood set. Link: https://lore.kernel.org/all/20220928073709.1b93b74a@kernel.org/ Reviewed-by: Johannes Berg Acked-by: Nikolay Aleksandrov Reviewed-by: Nicolas Dichtel Reviewed-by: Guillaume Nault Signed-off-by: Jakub Kicinski -- RESEND with the right tree in the subject CC: Florent Fourcot CC: Pablo Neira Ayuso CC: Florian Westphal CC: Jamal Hadi Salim CC: Jacob Keller CC: Hangbin Liu --- net/netlink/genetlink.c | 32 +++++++++++++++++++++++++++++++- 1 file changed, 31 insertions(+), 1 deletion(-) diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c index 7c136de117eb..39b7c00e4cef 100644 --- a/net/netlink/genetlink.c +++ b/net/netlink/genetlink.c @@ -739,6 +739,36 @@ static int genl_family_rcv_msg_doit(const struct genl_family *family, return err; } +static int genl_header_check(const struct genl_family *family, + struct nlmsghdr *nlh, struct genlmsghdr *hdr, + struct netlink_ext_ack *extack) +{ + u16 flags; + + /* Only for commands added after we started validating */ + if (hdr->cmd < family->resv_start_op) + return 0; + + if (hdr->reserved) { + NL_SET_ERR_MSG(extack, "genlmsghdr.reserved field is not 0"); + return -EINVAL; + } + + /* Old netlink flags have pretty loose semantics, allow only the flags + * consumed by the core where we can enforce the meaning. + */ + flags = nlh->nlmsg_flags; + if ((flags & NLM_F_DUMP) == NLM_F_DUMP) /* DUMP is 2 bits */ + flags &= ~NLM_F_DUMP; + if (flags & ~(NLM_F_REQUEST | NLM_F_ACK | NLM_F_ECHO)) { + NL_SET_ERR_MSG(extack, + "ambiguous or reserved bits set in nlmsg_flags"); + return -EINVAL; + } + + return 0; +} + static int genl_family_rcv_msg(const struct genl_family *family, struct sk_buff *skb, struct nlmsghdr *nlh, @@ -757,7 +787,7 @@ static int genl_family_rcv_msg(const struct genl_family *family, if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen)) return -EINVAL; - if (hdr->cmd >= family->resv_start_op && hdr->reserved) + if (genl_header_check(family, nlh, hdr, extack)) return -EINVAL; if (genl_get_cmd(hdr->cmd, family, &op)) -- 2.37.3