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 X-Spam-Level: X-Spam-Status: No, score=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 6FC37C433E6 for ; Wed, 24 Feb 2021 13:22:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 186A964EEC for ; Wed, 24 Feb 2021 13:22:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235230AbhBXNT0 (ORCPT ); Wed, 24 Feb 2021 08:19:26 -0500 Received: from mail.kernel.org ([198.145.29.99]:58448 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232137AbhBXNIm (ORCPT ); Wed, 24 Feb 2021 08:08:42 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8AD8064F19; Wed, 24 Feb 2021 12:55:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1614171301; bh=d+pnYoD9pnmVHjio02s/0OG0i3lMIpPT+tZE/Hi8ttY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BmtppXWcmlIxOb0Jp85AVWMAwdEC81IlHdxVPlnvDC6+Fy7hpG8/k27QuMs8NVblC 98YUUtqTEpyufoYS4Nb+mrGtcDHDxhnVrd/og2cTJdgF8nnb58Ey6GClEFkmydUJe+ O2hI7gJRWgx5H+7m6PMvZYIXQ1sjI+SSQy6iIh/EvLGN1/yz0z2Y2rQPWh9HBDouqf RiqiMkIOVX5d9osf18lfVosP5nxErE4+YsxtR1sQClQ8SmBy72WKnGCuhPZXAafed/ EcSlIGeqHo6oWxuXantU9tI0A+VtBjurLPdYBDO9Sklczk4jkYOd2WDANNxFagIAGg D8LAu/h7hX9cA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Sabyrzhan Tasbolatov , syzbot+a71a442385a0b2815497@syzkaller.appspotmail.com, Casey Schaufler , Sasha Levin , linux-security-module@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 20/26] smackfs: restrict bytes count in smackfs write functions Date: Wed, 24 Feb 2021 07:54:28 -0500 Message-Id: <20210224125435.483539-20-sashal@kernel.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210224125435.483539-1-sashal@kernel.org> References: <20210224125435.483539-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sabyrzhan Tasbolatov [ Upstream commit 7ef4c19d245f3dc233fd4be5acea436edd1d83d8 ] syzbot found WARNINGs in several smackfs write operations where bytes count is passed to memdup_user_nul which exceeds GFP MAX_ORDER. Check count size if bigger than PAGE_SIZE. Per smackfs doc, smk_write_net4addr accepts any label or -CIPSO, smk_write_net6addr accepts any label or -DELETE. I couldn't find any general rule for other label lengths except SMK_LABELLEN, SMK_LONGLABEL, SMK_CIPSOMAX which are documented. Let's constrain, in general, smackfs label lengths for PAGE_SIZE. Although fuzzer crashes write to smackfs/netlabel on 0x400000 length. Here is a quick way to reproduce the WARNING: python -c "print('A' * 0x400000)" > /sys/fs/smackfs/netlabel Reported-by: syzbot+a71a442385a0b2815497@syzkaller.appspotmail.com Signed-off-by: Sabyrzhan Tasbolatov Signed-off-by: Casey Schaufler Signed-off-by: Sasha Levin --- security/smack/smackfs.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c index accd3846f1e3e..4f8c1a272df07 100644 --- a/security/smack/smackfs.c +++ b/security/smack/smackfs.c @@ -1191,7 +1191,7 @@ static ssize_t smk_write_net4addr(struct file *file, const char __user *buf, return -EPERM; if (*ppos != 0) return -EINVAL; - if (count < SMK_NETLBLADDRMIN) + if (count < SMK_NETLBLADDRMIN || count > PAGE_SIZE - 1) return -EINVAL; data = memdup_user_nul(buf, count); @@ -1451,7 +1451,7 @@ static ssize_t smk_write_net6addr(struct file *file, const char __user *buf, return -EPERM; if (*ppos != 0) return -EINVAL; - if (count < SMK_NETLBLADDRMIN) + if (count < SMK_NETLBLADDRMIN || count > PAGE_SIZE - 1) return -EINVAL; data = memdup_user_nul(buf, count); @@ -1858,6 +1858,10 @@ static ssize_t smk_write_ambient(struct file *file, const char __user *buf, if (!smack_privileged(CAP_MAC_ADMIN)) return -EPERM; + /* Enough data must be present */ + if (count == 0 || count > PAGE_SIZE) + return -EINVAL; + data = memdup_user_nul(buf, count); if (IS_ERR(data)) return PTR_ERR(data); @@ -2029,6 +2033,9 @@ static ssize_t smk_write_onlycap(struct file *file, const char __user *buf, if (!smack_privileged(CAP_MAC_ADMIN)) return -EPERM; + if (count > PAGE_SIZE) + return -EINVAL; + data = memdup_user_nul(buf, count); if (IS_ERR(data)) return PTR_ERR(data); @@ -2116,6 +2123,9 @@ static ssize_t smk_write_unconfined(struct file *file, const char __user *buf, if (!smack_privileged(CAP_MAC_ADMIN)) return -EPERM; + if (count > PAGE_SIZE) + return -EINVAL; + data = memdup_user_nul(buf, count); if (IS_ERR(data)) return PTR_ERR(data); @@ -2669,6 +2679,10 @@ static ssize_t smk_write_syslog(struct file *file, const char __user *buf, if (!smack_privileged(CAP_MAC_ADMIN)) return -EPERM; + /* Enough data must be present */ + if (count == 0 || count > PAGE_SIZE) + return -EINVAL; + data = memdup_user_nul(buf, count); if (IS_ERR(data)) return PTR_ERR(data); @@ -2761,10 +2775,13 @@ static ssize_t smk_write_relabel_self(struct file *file, const char __user *buf, return -EPERM; /* + * No partial write. * Enough data must be present. */ if (*ppos != 0) return -EINVAL; + if (count == 0 || count > PAGE_SIZE) + return -EINVAL; data = memdup_user_nul(buf, count); if (IS_ERR(data)) -- 2.27.0