From patchwork Mon Jan 7 12:11:28 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Taehee Yoo X-Patchwork-Id: 1021284 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=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; 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.b="SU3RxPI0"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 43YDlM4bmPz9sNK for ; Mon, 7 Jan 2019 23:11:43 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727001AbfAGMLh (ORCPT ); Mon, 7 Jan 2019 07:11:37 -0500 Received: from mail-pf1-f193.google.com ([209.85.210.193]:45739 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726485AbfAGMLh (ORCPT ); Mon, 7 Jan 2019 07:11:37 -0500 Received: by mail-pf1-f193.google.com with SMTP id g62so51956pfd.12; Mon, 07 Jan 2019 04:11:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=Aa5tu8ePszw0nciQVUDoZTAH6B34pZH2n0LXGrrctAQ=; b=SU3RxPI0dxYHMzRF3VJJYoPHcHD4uCEMdXNO6V59r7a6DrDweht6LWAlPshHk7zrfN 7qbvzSbMDpt0njnB4MGqbVhwmL0qWbdZZjzFpdhbZ1P0mFOVHkZiJg8zVu2gCFzJIcPR 55xarbPjnkIOFhDNJY8LHJIEuuwBV4NPQzneBUcs+2QDosKaJbOBtWnZD+5t+QKlzOzi 9XP+faxytjdjaNVevnT6qYq3qm6kb6rd5RijfZIKGyu6ChD0QdbyX8CDn8KN55o/MlDv rXxEW05Ne3asZjDo9kCqBxVfsCSi1yfeMxDL25ptMdB64+O2fOAozGgp9j9kLKGDuiTr lwXQ== 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; bh=Aa5tu8ePszw0nciQVUDoZTAH6B34pZH2n0LXGrrctAQ=; b=gZ2I2iC4ZLK4u2CLdPz38WSWHQkhq8JDxhjjshlP26bloKUOSXgJ/RA4w9vH70Z0Vj 3byDrG6v1cy6OpZ1Z1kogC5xVUN77djh1a/bNMU7l5SRNRHGROM+oqA1S0YUsVl9yVCY zOiqu8p23ILE/AyYnsyHy8KQlLcwyNUlEPGrzWFVHKfVW48y5XmTX69FN5cBQK7swO8M 2GzZY8vKJ7AJazo9pa0PG2i7v6rZfkhzdcv+eojV8rzMARq4+VG/CWrCQmOGevjt27bw 5Gdw3X4ZM45GMD3PEeeLBpgVSoGYin4FD+LasvfUt+uHSBbM6M3KiphgIO/LwUEiSpvh 6WWg== X-Gm-Message-State: AJcUukfUgmjiNiXkc01etdheqqV0MeE64pMAmZf8QvImSDzAr9EgUkea xl1eeiLasXOjo+sOEmOpYlE= X-Google-Smtp-Source: ALg8bN4yKRukNu2STSFS/7YeDCKzMxMNSgxvWzREQZI9E4tJVDY7IKZ/f+zRDMRN5U80cV38DoswHQ== X-Received: by 2002:a63:5f50:: with SMTP id t77mr10761603pgb.76.1546863095611; Mon, 07 Jan 2019 04:11:35 -0800 (PST) Received: from ap-To-be-filled-by-O-E-M.8.8.8.8 ([14.33.120.60]) by smtp.gmail.com with ESMTPSA id u123sm87665077pfb.1.2019.01.07.04.11.33 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 07 Jan 2019 04:11:34 -0800 (PST) From: Taehee Yoo To: davem@davemloft.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, daniel@iogearbox.net, ast@kernel.org, mcgrof@kernel.org Cc: ap420073@gmail.com Subject: [PATCH net v3 4/4] net: bpfilter: disallow to remove bpfilter module while being used Date: Mon, 7 Jan 2019 21:11:28 +0900 Message-Id: <20190107121128.13878-1-ap420073@gmail.com> X-Mailer: git-send-email 2.17.1 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The bpfilter.ko module can be removed while functions of the bpfilter.ko are executing. so panic can occurred. in order to protect that, locks can be used. a bpfilter_lock protects routines in the __bpfilter_process_sockopt() but it's not enough because __exit routine can be executed concurrently. Now, the bpfilter_umh can not run in parallel. So, the module do not removed while it's being used and it do not double-create UMH process. The members of the umh_info and the bpfilter_umh_ops are protected by the bpfilter_umh_ops.lock. test commands: while : do iptables -I FORWARD -m string --string ap --algo kmp & modprobe -rv bpfilter & done splat looks like: [ 298.623435] BUG: unable to handle kernel paging request at fffffbfff807440b [ 298.628512] #PF error: [normal kernel read fault] [ 298.633018] PGD 124327067 P4D 124327067 PUD 11c1a3067 PMD 119eb2067 PTE 0 [ 298.638859] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI [ 298.638859] CPU: 0 PID: 2997 Comm: iptables Not tainted 4.20.0+ #154 [ 298.638859] RIP: 0010:__mutex_lock+0x6b9/0x16a0 [ 298.638859] Code: c0 00 00 e8 89 82 ff ff 80 bd 8f fc ff ff 00 0f 85 d9 05 00 00 48 8b 85 80 fc ff ff 48 bf 00 00 00 00 00 fc ff df 48 c1 e8 03 <80> 3c 38 00 0f 85 1d 0e 00 00 48 8b 85 c8 fc ff ff 49 39 47 58 c6 [ 298.638859] RSP: 0018:ffff88810e7777a0 EFLAGS: 00010202 [ 298.638859] RAX: 1ffffffff807440b RBX: ffff888111bd4d80 RCX: 0000000000000000 [ 298.638859] RDX: 1ffff110235ff806 RSI: ffff888111bd5538 RDI: dffffc0000000000 [ 298.638859] RBP: ffff88810e777b30 R08: 0000000080000002 R09: 0000000000000000 [ 298.638859] R10: 0000000000000000 R11: 0000000000000000 R12: fffffbfff168a42c [ 298.638859] R13: ffff888111bd4d80 R14: ffff8881040e9a05 R15: ffffffffc03a2000 [ 298.638859] FS: 00007f39e3758700(0000) GS:ffff88811ae00000(0000) knlGS:0000000000000000 [ 298.638859] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 298.638859] CR2: fffffbfff807440b CR3: 000000011243e000 CR4: 00000000001006f0 [ 298.638859] Call Trace: [ 298.638859] ? mutex_lock_io_nested+0x1560/0x1560 [ 298.638859] ? kasan_kmalloc+0xa0/0xd0 [ 298.638859] ? kmem_cache_alloc+0x1c2/0x260 [ 298.638859] ? __alloc_file+0x92/0x3c0 [ 298.638859] ? alloc_empty_file+0x43/0x120 [ 298.638859] ? alloc_file_pseudo+0x220/0x330 [ 298.638859] ? sock_alloc_file+0x39/0x160 [ 298.638859] ? __sys_socket+0x113/0x1d0 [ 298.638859] ? __x64_sys_socket+0x6f/0xb0 [ 298.638859] ? do_syscall_64+0x138/0x560 [ 298.638859] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 298.638859] ? __alloc_file+0x92/0x3c0 [ 298.638859] ? init_object+0x6b/0x80 [ 298.638859] ? cyc2ns_read_end+0x10/0x10 [ 298.638859] ? cyc2ns_read_end+0x10/0x10 [ 298.638859] ? hlock_class+0x140/0x140 [ 298.638859] ? sched_clock_local+0xd4/0x140 [ 298.638859] ? sched_clock_local+0xd4/0x140 [ 298.638859] ? check_flags.part.37+0x440/0x440 [ 298.638859] ? __lock_acquire+0x4f90/0x4f90 [ 298.638859] ? set_rq_offline.part.89+0x140/0x140 [ ... ] Fixes: d2ba09c17a06 ("net: add skeleton of bpfilter kernel module") Signed-off-by: Taehee Yoo --- include/linux/bpfilter.h | 2 ++ net/bpfilter/bpfilter_kern.c | 20 ++++++-------------- net/ipv4/bpfilter/sockopt.c | 21 ++++++++++++++++----- 3 files changed, 24 insertions(+), 19 deletions(-) diff --git a/include/linux/bpfilter.h b/include/linux/bpfilter.h index 8ebcbdd70bdc..d815622cd31e 100644 --- a/include/linux/bpfilter.h +++ b/include/linux/bpfilter.h @@ -12,6 +12,8 @@ int bpfilter_ip_get_sockopt(struct sock *sk, int optname, char __user *optval, int __user *optlen); struct bpfilter_umh_ops { struct umh_info info; + /* since ip_getsockopt() can run in parallel, serialize access to umh */ + struct mutex lock; int (*sockopt)(struct sock *sk, int optname, char __user *optval, unsigned int optlen, bool is_set); diff --git a/net/bpfilter/bpfilter_kern.c b/net/bpfilter/bpfilter_kern.c index 33d6b159ba88..eedb83863cb0 100644 --- a/net/bpfilter/bpfilter_kern.c +++ b/net/bpfilter/bpfilter_kern.c @@ -13,9 +13,6 @@ extern char bpfilter_umh_start; extern char bpfilter_umh_end; -/* since ip_getsockopt() can run in parallel, serialize access to umh */ -static DEFINE_MUTEX(bpfilter_lock); - static void shutdown_umh(void) { struct task_struct *tsk; @@ -36,13 +33,6 @@ static void __stop_umh(void) shutdown_umh(); } -static void stop_umh(void) -{ - mutex_lock(&bpfilter_lock); - __stop_umh(); - mutex_unlock(&bpfilter_lock); -} - static int __bpfilter_process_sockopt(struct sock *sk, int optname, char __user *optval, unsigned int optlen, bool is_set) @@ -58,7 +48,6 @@ static int __bpfilter_process_sockopt(struct sock *sk, int optname, req.cmd = optname; req.addr = (long __force __user)optval; req.len = optlen; - mutex_lock(&bpfilter_lock); if (!bpfilter_ops.info.pid) goto out; n = __kernel_write(bpfilter_ops.info.pipe_to_umh, &req, sizeof(req), @@ -80,7 +69,6 @@ static int __bpfilter_process_sockopt(struct sock *sk, int optname, } ret = reply.status; out: - mutex_unlock(&bpfilter_lock); return ret; } @@ -99,7 +87,7 @@ static int start_umh(void) /* health check that usermode process started correctly */ if (__bpfilter_process_sockopt(NULL, 0, NULL, 0, 0) != 0) { - stop_umh(); + shutdown_umh(); return -EFAULT; } @@ -110,22 +98,26 @@ static int __init load_umh(void) { int err; + mutex_lock(&bpfilter_ops.lock); err = start_umh(); if (!err && IS_ENABLED(CONFIG_INET)) { bpfilter_ops.sockopt = &__bpfilter_process_sockopt; bpfilter_ops.start = &start_umh; } + mutex_unlock(&bpfilter_ops.lock); return err; } static void __exit fini_umh(void) { + mutex_lock(&bpfilter_ops.lock); if (IS_ENABLED(CONFIG_INET)) { + shutdown_umh(); bpfilter_ops.start = NULL; bpfilter_ops.sockopt = NULL; } - stop_umh(); + mutex_unlock(&bpfilter_ops.lock); } module_init(load_umh); module_exit(fini_umh); diff --git a/net/ipv4/bpfilter/sockopt.c b/net/ipv4/bpfilter/sockopt.c index de84ede4e765..2611f7a7f3d1 100644 --- a/net/ipv4/bpfilter/sockopt.c +++ b/net/ipv4/bpfilter/sockopt.c @@ -14,10 +14,12 @@ EXPORT_SYMBOL_GPL(bpfilter_ops); static void bpfilter_umh_cleanup(struct umh_info *info) { + mutex_lock(&bpfilter_ops.lock); bpfilter_ops.stop = true; fput(info->pipe_to_umh); fput(info->pipe_from_umh); info->pid = 0; + mutex_unlock(&bpfilter_ops.lock); } static int bpfilter_mbox_request(struct sock *sk, int optname, @@ -26,20 +28,28 @@ static int bpfilter_mbox_request(struct sock *sk, int optname, { int err; + mutex_lock(&bpfilter_ops.lock); if (!bpfilter_ops.sockopt) { + mutex_unlock(&bpfilter_ops.lock); err = request_module("bpfilter"); + mutex_lock(&bpfilter_ops.lock); if (err) - return err; - if (!bpfilter_ops.sockopt) - return -ECHILD; + goto out; + if (!bpfilter_ops.sockopt) { + err = -ECHILD; + goto out; + } } if (bpfilter_ops.stop) { err = bpfilter_ops.start(); if (err) - return err; + goto out; } - return bpfilter_ops.sockopt(sk, optname, optval, optlen, is_set); + err = bpfilter_ops.sockopt(sk, optname, optval, optlen, is_set); +out: + mutex_unlock(&bpfilter_ops.lock); + return err; } int bpfilter_ip_set_sockopt(struct sock *sk, int optname, char __user *optval, @@ -61,6 +71,7 @@ int bpfilter_ip_get_sockopt(struct sock *sk, int optname, char __user *optval, static int __init bpfilter_sockopt_init(void) { + mutex_init(&bpfilter_ops.lock); bpfilter_ops.stop = true; bpfilter_ops.info.cmdline = "bpfilter_umh"; bpfilter_ops.info.cleanup = &bpfilter_umh_cleanup;