From patchwork Wed Nov 6 02:24:26 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kuniyuki Iwashima X-Patchwork-Id: 13863842 X-Patchwork-Delegate: kuba@kernel.org Received: from smtp-fw-6002.amazon.com (smtp-fw-6002.amazon.com [52.95.49.90]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 315BF18FC81 for ; Wed, 6 Nov 2024 02:25:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=52.95.49.90 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730859906; cv=none; b=LP5CvOe0Hq+akz0jD+SvacNVmY2qa8GbHKq6s22oMBkfUv7MTLmi1gqgemw36VrtK9AfNYdUX+luTSIlAe/5bTWETLst7XOZo+lIceCDayij+xBtJwmWAIE/7RDFKZ/6ZDrV+16DWYykXVFIi1Byu//Rl0boOFD+2UkBAGdw61U= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730859906; c=relaxed/simple; bh=mgMPXp/Umcf564mwO4xjfmYj6DyvhTN88OcPNnDMz0Y=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=m5vqBZ5oh5pGIP3RFxchGk17xk8iC+zthTMZae4zh+mqHVRBUPKmhfobzQd/xVtqLq/KxO4A8AzGltU1CHjYUBw1QdWwrkCqn5Rd2YgYGmpxHQfkpZNvu92mFYHHWwt3ERVbS4nss35wD9v4OjNroXwtwEAg1U6mYSV5jxsXRPM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com; spf=pass smtp.mailfrom=amazon.co.jp; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b=bIDvR5zf; arc=none smtp.client-ip=52.95.49.90 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.co.jp Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="bIDvR5zf" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1730859904; x=1762395904; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=d1m/N81QT+tePNxRmD+pHNTYOKxskE7NJ4uryXLXhYM=; b=bIDvR5zfPjf9iOPD1N6Ltgb9B4eMXz9cQ9lz9AYNO4BjBrTiKDPfIfdn 3vsvBf7SNlZN7PA93zYjeH9NYQ8EZB//yORI77od/N/kw3YJXZUgIfO6B 7XtrlnfN+7b5vJfLMejcXFB5dP3/bukvmz3I8WjeT3uhp83zEChMUtk6+ 8=; X-IronPort-AV: E=Sophos;i="6.11,261,1725321600"; d="scan'208";a="446706402" Received: from iad12-co-svc-p1-lb1-vlan3.amazon.com (HELO smtpout.prod.us-west-2.prod.farcaster.email.amazon.dev) ([10.43.8.6]) by smtp-border-fw-6002.iad6.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Nov 2024 02:25:01 +0000 Received: from EX19MTAUWB001.ant.amazon.com [10.0.7.35:48625] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.34.72:2525] with esmtp (Farcaster) id c19a0965-ef88-4724-8e2a-91fffd046ebd; Wed, 6 Nov 2024 02:24:59 +0000 (UTC) X-Farcaster-Flow-ID: c19a0965-ef88-4724-8e2a-91fffd046ebd Received: from EX19D004ANA001.ant.amazon.com (10.37.240.138) by EX19MTAUWB001.ant.amazon.com (10.250.64.248) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.34; Wed, 6 Nov 2024 02:24:59 +0000 Received: from 6c7e67c6786f.amazon.com (10.187.170.17) by EX19D004ANA001.ant.amazon.com (10.37.240.138) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.35; Wed, 6 Nov 2024 02:24:56 +0000 From: Kuniyuki Iwashima To: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman CC: Andrew Lunn , Marc Kleine-Budde , Vincent Mailhol , "Daniel Borkmann" , Nikolay Aleksandrov , Kuniyuki Iwashima , Kuniyuki Iwashima , Subject: [PATCH v2 net-next 1/7] rtnetlink: Introduce struct rtnl_nets and helpers. Date: Tue, 5 Nov 2024 18:24:26 -0800 Message-ID: <20241106022432.13065-2-kuniyu@amazon.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20241106022432.13065-1-kuniyu@amazon.com> References: <20241106022432.13065-1-kuniyu@amazon.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: EX19D035UWA003.ant.amazon.com (10.13.139.86) To EX19D004ANA001.ant.amazon.com (10.37.240.138) X-Patchwork-Delegate: kuba@kernel.org rtnl_newlink() needs to hold 3 per-netns RTNL: 2 for a new device and 1 for its peer. We will add rtnl_nets_lock() later, which performs the nested locking based on struct rtnl_nets, which has an array of struct net pointers. rtnl_nets_add() adds a net pointer to the array and sorts it so that rtnl_nets_lock() can simply acquire per-netns RTNL from array[0] to [2]. Before calling rtnl_nets_add(), get_net() must be called for the net, and rtnl_nets_destroy() will call put_net() for each. Let's apply the helpers to rtnl_newlink(). When CONFIG_DEBUG_NET_SMALL_RTNL is disabled, we do not call rtnl_net_lock() thus do not care about the array order, so rtnl_net_cmp_locks() returns -1 so that the loop in rtnl_nets_add() can be optimised to NOP. Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet --- v2: * Move struct rtnl_nets to net/core/rtnetlink.c * Unexport rtnl_nets_add() --- net/core/rtnetlink.c | 70 ++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 67 insertions(+), 3 deletions(-) diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 3b33810d92a8..81f4722c1353 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -258,8 +258,67 @@ bool lockdep_rtnl_net_is_held(struct net *net) return lockdep_rtnl_is_held() && lockdep_is_held(&net->rtnl_mutex); } EXPORT_SYMBOL(lockdep_rtnl_net_is_held); +#else +static int rtnl_net_cmp_locks(const struct net *net_a, const struct net *net_b) +{ + /* No need to swap */ + return -1; +} #endif +struct rtnl_nets { + /* ->newlink() needs to freeze 3 netns at most; + * 2 for the new device, 1 for its peer. + */ + struct net *net[3]; + unsigned char len; +}; + +static void rtnl_nets_init(struct rtnl_nets *rtnl_nets) +{ + memset(rtnl_nets, 0, sizeof(*rtnl_nets)); +} + +static void rtnl_nets_destroy(struct rtnl_nets *rtnl_nets) +{ + int i; + + for (i = 0; i < rtnl_nets->len; i++) { + put_net(rtnl_nets->net[i]); + rtnl_nets->net[i] = NULL; + } + + rtnl_nets->len = 0; +} + +/** + * rtnl_nets_add - Add netns to be locked before ->newlink(). + * + * @rtnl_nets: rtnl_nets pointer passed to ->get_peer_net(). + * @net: netns pointer with an extra refcnt held. + * + * The extra refcnt is released in rtnl_nets_destroy(). + */ +static void rtnl_nets_add(struct rtnl_nets *rtnl_nets, struct net *net) +{ + int i; + + DEBUG_NET_WARN_ON_ONCE(rtnl_nets->len == ARRAY_SIZE(rtnl_nets->net)); + + for (i = 0; i < rtnl_nets->len; i++) { + switch (rtnl_net_cmp_locks(rtnl_nets->net[i], net)) { + case 0: + put_net(net); + return; + case 1: + swap(rtnl_nets->net[i], net); + } + } + + rtnl_nets->net[i] = net; + rtnl_nets->len++; +} + static struct rtnl_link __rcu *__rcu *rtnl_msg_handlers[RTNL_FAMILY_MAX + 1]; static inline int rtm_msgindex(int msgtype) @@ -3796,6 +3855,7 @@ static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh, struct net *tgt_net, *link_net = NULL; struct rtnl_link_ops *ops = NULL; struct rtnl_newlink_tbs *tbs; + struct rtnl_nets rtnl_nets; int ops_srcu_index; int ret; @@ -3839,6 +3899,8 @@ static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh, #endif } + rtnl_nets_init(&rtnl_nets); + if (ops) { if (ops->maxtype > RTNL_MAX_TYPE) { ret = -EINVAL; @@ -3868,6 +3930,8 @@ static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh, goto put_ops; } + rtnl_nets_add(&rtnl_nets, tgt_net); + if (tb[IFLA_LINK_NETNSID]) { int id = nla_get_s32(tb[IFLA_LINK_NETNSID]); @@ -3878,6 +3942,8 @@ static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh, goto put_net; } + rtnl_nets_add(&rtnl_nets, link_net); + if (!netlink_ns_capable(skb, link_net->user_ns, CAP_NET_ADMIN)) { ret = -EPERM; goto put_net; @@ -3887,9 +3953,7 @@ static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh, ret = __rtnl_newlink(skb, nlh, ops, tgt_net, link_net, tbs, data, extack); put_net: - if (link_net) - put_net(link_net); - put_net(tgt_net); + rtnl_nets_destroy(&rtnl_nets); put_ops: if (ops) rtnl_link_ops_put(ops, ops_srcu_index);