From patchwork Wed Mar 10 20:58:40 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johannes Berg X-Patchwork-Id: 12129357 X-Patchwork-Delegate: johannes@sipsolutions.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 30303C433DB for ; Wed, 10 Mar 2021 20:59:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DFF4A64FC5 for ; Wed, 10 Mar 2021 20:59:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231197AbhCJU7H (ORCPT ); Wed, 10 Mar 2021 15:59:07 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59638 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230491AbhCJU6t (ORCPT ); Wed, 10 Mar 2021 15:58:49 -0500 Received: from sipsolutions.net (s3.sipsolutions.net [IPv6:2a01:4f8:191:4433::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 72CBEC061574 for ; Wed, 10 Mar 2021 12:58:49 -0800 (PST) Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.94) (envelope-from ) id 1lK5ul-00EUn1-T3; Wed, 10 Mar 2021 21:58:43 +0100 From: Johannes Berg To: linux-wireless@vger.kernel.org Cc: Johannes Berg , Sid Hayn Subject: [PATCH] nl80211: fix locking for wireless device netns change Date: Wed, 10 Mar 2021 21:58:40 +0100 Message-Id: <20210310215839.eadf7c43781b.I5fc6cf6676f800ab8008e03bbea9c3349b02d804@changeid> X-Mailer: git-send-email 2.29.2 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org From: Johannes Berg We have all the network interfaces marked as netns-local since the only reasonable thing to do right now is to set a whole device, including all netdevs, into a different network namespace. For this reason, we also have our own way of changing the network namespace. Unfortunately, the RTNL locking changes broke this, and it now results in many RTNL assertions. The trivial fix for those (just hold RTNL for the changes) however leads to deadlocks in the cfg80211 netdev notifier. Since we only need the wiphy, and that's still protected by the RTNL, add a new NL80211_FLAG_NO_WIPHY_MTX flag to the nl80211 ops and use it to _not_ take the wiphy mutex but only the RTNL. This way, the notifier does all the work necessary during unregistration/registration of the netdevs from the old and in the new namespace. Reported-by: Sid Hayn Fixes: a05829a7222e ("cfg80211: avoid holding the RTNL when calling the driver") Signed-off-by: Johannes Berg --- net/wireless/nl80211.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c index 521d36bb0803..ae6097fff133 100644 --- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -14789,6 +14789,7 @@ static int nl80211_set_tid_config(struct sk_buff *skb, #define NL80211_FLAG_NEED_WDEV_UP (NL80211_FLAG_NEED_WDEV |\ NL80211_FLAG_CHECK_NETDEV_UP) #define NL80211_FLAG_CLEAR_SKB 0x20 +#define NL80211_FLAG_NO_WIPHY_MTX 0x40 static int nl80211_pre_doit(const struct genl_ops *ops, struct sk_buff *skb, struct genl_info *info) @@ -14840,7 +14841,7 @@ static int nl80211_pre_doit(const struct genl_ops *ops, struct sk_buff *skb, info->user_ptr[0] = rdev; } - if (rdev) { + if (rdev && !(ops->internal_flags & NL80211_FLAG_NO_WIPHY_MTX)) { wiphy_lock(&rdev->wiphy); /* we keep the mutex locked until post_doit */ __release(&rdev->wiphy.mtx); @@ -14865,7 +14866,8 @@ static void nl80211_post_doit(const struct genl_ops *ops, struct sk_buff *skb, } } - if (info->user_ptr[0]) { + if (info->user_ptr[0] && + !(ops->internal_flags & NL80211_FLAG_NO_WIPHY_MTX)) { struct cfg80211_registered_device *rdev = info->user_ptr[0]; /* we kept the mutex locked since pre_doit */ @@ -15329,7 +15331,9 @@ static const struct genl_small_ops nl80211_small_ops[] = { .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, .doit = nl80211_wiphy_netns, .flags = GENL_UNS_ADMIN_PERM, - .internal_flags = NL80211_FLAG_NEED_WIPHY, + .internal_flags = NL80211_FLAG_NEED_WIPHY | + NL80211_FLAG_NEED_RTNL | + NL80211_FLAG_NO_WIPHY_MTX, }, { .cmd = NL80211_CMD_GET_SURVEY,