From patchwork Thu Jul 2 18:52:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Cong Wang X-Patchwork-Id: 1321870 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20161025 header.b=a0ZAZ77n; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 49yS0P386tz9sQt for ; Fri, 3 Jul 2020 04:53:09 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726030AbgGBSxH (ORCPT ); Thu, 2 Jul 2020 14:53:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60080 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725878AbgGBSxG (ORCPT ); Thu, 2 Jul 2020 14:53:06 -0400 Received: from mail-pj1-x1042.google.com (mail-pj1-x1042.google.com [IPv6:2607:f8b0:4864:20::1042]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E8967C08C5C1 for ; Thu, 2 Jul 2020 11:53:05 -0700 (PDT) Received: by mail-pj1-x1042.google.com with SMTP id h22so12906335pjf.1 for ; Thu, 02 Jul 2020 11:53:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=URd915rQSgqAfDLKyjrPsB58MLy827wyrlr6KMAyZXQ=; b=a0ZAZ77nVFnJEFPgPGeZrzjaITBubxP0ADvb/MwF0MhpzXwCE+yp4qDcLzkQA23f2m bgAU5LTcmc4ePPfp8beuTEqHTiJThBbUi9HjYv6xm6A9OiAurNdTlyKvV8jBSuiBME6x cDjcqrhDiNv0mcrX499UhJ4rx6NVRbmyiVbfz1LHJmnZWYVH57l/or/p/Cmek1KA8H1I 5r++kdYx2B0V7K/UKfvL+XZpuMgDOuef+UE4iBR0k5PlwE1tiOpylaza4lm4s5xhJRKc BdfCJ/60jKTYdstgnPRX4GLiRuJYhoTKMfuO6wA5OotF5ufl0n6eaXzkyerdgkeHQIhr qeWw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=URd915rQSgqAfDLKyjrPsB58MLy827wyrlr6KMAyZXQ=; b=n5dqJeA3X7Hz9Z4t2pZendgDqcsQl+BIWZW2zdY97DluOyqeFoCoqSTbwpd24QllPO z9RJkIetEi+rxhYhyAz6ecgboYKFFQjeZjSkVAA25ZnlSatHtiM0V+MTqsXOtt//fQGh 0W9eqS8sAF5wAn9SB4mZBMCfkw7kbNyI+yvmrSEksVumrun8yI1tViy8Sp/X8fU5VG7+ 2LOjVzBPGx6Ne9t594SL79JBCUj9Lhj/2qcVPauOHU9s4CU/tqxZFIMWMmsxiAg3SbmB tY5VD/VpuqJykjWHbaA8HIrdU177xR13r8nnahM3EJl/SlpwINUxDYitiYBCzBLhQOZc 3kNg== X-Gm-Message-State: AOAM531vcvwnxX9J101yfPn+pNzP1XzXbgflfOoifc6TJ6Hdc2eVgTmb moBa3uo+kNd9trvjTVFd1f1nTrqRzCI= X-Google-Smtp-Source: ABdhPJwro06a7fy1o9vIU2yt5G85sDC2JW9B7OBuo1M3uv2K+PqmmkdcOIjQbKCvJKj49N+C7LgMmw== X-Received: by 2002:a17:90b:30d0:: with SMTP id hi16mr35759023pjb.65.1593715985169; Thu, 02 Jul 2020 11:53:05 -0700 (PDT) Received: from MacBookAir.linux-6brj.site ([2600:1700:727f::e]) by smtp.gmail.com with ESMTPSA id i128sm9823341pfe.74.2020.07.02.11.53.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 02 Jul 2020 11:53:04 -0700 (PDT) From: Cong Wang To: netdev@vger.kernel.org Cc: Cong Wang , Cameron Berkenpas , Peter Geis , Lu Fengqi , =?utf-8?q?Dani=C3=ABl_Sonck?= , Zhang Qiang , Thomas Lamprecht , Daniel Borkmann , Zefan Li , Tejun Heo , Roman Gushchin Subject: [Patch net v2] cgroup: fix cgroup_sk_alloc() for sk_clone_lock() Date: Thu, 2 Jul 2020 11:52:56 -0700 Message-Id: <20200702185256.17917-1-xiyou.wangcong@gmail.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org When we clone a socket in sk_clone_lock(), its sk_cgrp_data is copied, so the cgroup refcnt must be taken too. And, unlike the sk_alloc() path, sock_update_netprioidx() is not called here. Therefore, it is safe and necessary to grab the cgroup refcnt even when cgroup_sk_alloc is disabled. sk_clone_lock() is in BH context anyway, the in_interrupt() would terminate this function if called there. And for sk_alloc() skcd->val is always zero. So it's safe to factor out the code to make it more readable. The global variable 'cgroup_sk_alloc_disabled' is used to determine whether to take these reference counts. It is impossible to make the reference counting correct unless we save this bit of information in skcd->val. So, add a new bit there to record whether the socket has already taken the reference counts. This obviously relies on kmalloc() to align cgroup pointers to at least 4 bytes, ARCH_KMALLOC_MINALIGN is certainly larger than that. This bug seems to be introduced since the beginning, commit d979a39d7242 ("cgroup: duplicate cgroup reference when cloning sockets") tried to fix it but not compeletely. It seems not easy to trigger until the recent commit 090e28b229af ("netprio_cgroup: Fix unlimited memory leak of v2 cgroups") was merged. Fixes: bd1060a1d671 ("sock, cgroup: add sock->sk_cgroup") Reported-by: Cameron Berkenpas Reported-by: Peter Geis Reported-by: Lu Fengqi Reported-by: Daniël Sonck Reported-by: Zhang Qiang Tested-by: Cameron Berkenpas Tested-by: Peter Geis Tested-by: Thomas Lamprecht Cc: Daniel Borkmann Cc: Zefan Li Cc: Tejun Heo Cc: Roman Gushchin Signed-off-by: Cong Wang --- include/linux/cgroup-defs.h | 6 ++++-- include/linux/cgroup.h | 4 +++- kernel/cgroup/cgroup.c | 31 +++++++++++++++++++------------ net/core/sock.c | 2 +- 4 files changed, 27 insertions(+), 16 deletions(-) diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index 52661155f85f..4f1cd0edc57d 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -790,7 +790,8 @@ struct sock_cgroup_data { union { #ifdef __LITTLE_ENDIAN struct { - u8 is_data; + u8 is_data : 1; + u8 no_refcnt : 1; u8 padding; u16 prioidx; u32 classid; @@ -800,7 +801,8 @@ struct sock_cgroup_data { u32 classid; u16 prioidx; u8 padding; - u8 is_data; + u8 no_refcnt : 1; + u8 is_data : 1; } __packed; #endif u64 val; diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 4598e4da6b1b..618838c48313 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -822,6 +822,7 @@ extern spinlock_t cgroup_sk_update_lock; void cgroup_sk_alloc_disable(void); void cgroup_sk_alloc(struct sock_cgroup_data *skcd); +void cgroup_sk_clone(struct sock_cgroup_data *skcd); void cgroup_sk_free(struct sock_cgroup_data *skcd); static inline struct cgroup *sock_cgroup_ptr(struct sock_cgroup_data *skcd) @@ -835,7 +836,7 @@ static inline struct cgroup *sock_cgroup_ptr(struct sock_cgroup_data *skcd) */ v = READ_ONCE(skcd->val); - if (v & 1) + if (v & 3) return &cgrp_dfl_root.cgrp; return (struct cgroup *)(unsigned long)v ?: &cgrp_dfl_root.cgrp; @@ -847,6 +848,7 @@ static inline struct cgroup *sock_cgroup_ptr(struct sock_cgroup_data *skcd) #else /* CONFIG_CGROUP_DATA */ static inline void cgroup_sk_alloc(struct sock_cgroup_data *skcd) {} +static inline void cgroup_sk_clone(struct sock_cgroup_data *skcd) {} static inline void cgroup_sk_free(struct sock_cgroup_data *skcd) {} #endif /* CONFIG_CGROUP_DATA */ diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 1ea181a58465..dd247747ec14 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -6439,18 +6439,8 @@ void cgroup_sk_alloc_disable(void) void cgroup_sk_alloc(struct sock_cgroup_data *skcd) { - if (cgroup_sk_alloc_disabled) - return; - - /* Socket clone path */ - if (skcd->val) { - /* - * We might be cloning a socket which is left in an empty - * cgroup and the cgroup might have already been rmdir'd. - * Don't use cgroup_get_live(). - */ - cgroup_get(sock_cgroup_ptr(skcd)); - cgroup_bpf_get(sock_cgroup_ptr(skcd)); + if (cgroup_sk_alloc_disabled) { + skcd->no_refcnt = 1; return; } @@ -6475,10 +6465,27 @@ void cgroup_sk_alloc(struct sock_cgroup_data *skcd) rcu_read_unlock(); } +void cgroup_sk_clone(struct sock_cgroup_data *skcd) +{ + if (skcd->val) { + if (skcd->no_refcnt) + return; + /* + * We might be cloning a socket which is left in an empty + * cgroup and the cgroup might have already been rmdir'd. + * Don't use cgroup_get_live(). + */ + cgroup_get(sock_cgroup_ptr(skcd)); + cgroup_bpf_get(sock_cgroup_ptr(skcd)); + } +} + void cgroup_sk_free(struct sock_cgroup_data *skcd) { struct cgroup *cgrp = sock_cgroup_ptr(skcd); + if (skcd->no_refcnt) + return; cgroup_bpf_put(cgrp); cgroup_put(cgrp); } diff --git a/net/core/sock.c b/net/core/sock.c index d832c650287c..2e5b7870e5d3 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1926,7 +1926,7 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority) /* sk->sk_memcg will be populated at accept() time */ newsk->sk_memcg = NULL; - cgroup_sk_alloc(&newsk->sk_cgrp_data); + cgroup_sk_clone(&newsk->sk_cgrp_data); rcu_read_lock(); filter = rcu_dereference(sk->sk_filter);