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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 21A94C3F34F for ; Thu, 27 Feb 2020 13:43:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ED1E721D7E for ; Thu, 27 Feb 2020 13:43:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582811030; bh=D2UNR+MPHKFDoSdnx/q3n2QdWmDMWLZ48WZzdXaaRSo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=BEm6QT+eqmjJttsMdHbdhIusk8DY5pVLd+QprmIuSxiEzT97c7KHeCFgO6pfzLW5/ mQ/1vMtNY9wTgq8V5IeqKhuvtzWyH1h+AMUZPuF2siue4NL35lLX0PMMH/evfJK0hP 2LVa5L8QhDFIt0y97WgVg2BigYiOPuqu7cSetmXY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730036AbgB0Nnt (ORCPT ); Thu, 27 Feb 2020 08:43:49 -0500 Received: from mail.kernel.org ([198.145.29.99]:39044 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729696AbgB0Nno (ORCPT ); Thu, 27 Feb 2020 08:43:44 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8D4DE20726; Thu, 27 Feb 2020 13:43:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582811024; bh=D2UNR+MPHKFDoSdnx/q3n2QdWmDMWLZ48WZzdXaaRSo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1jiUjjOtXFxFr22DjPCOUPa43s0RHMCzhzxxkhRzh4ciwR1K5qkkKbkVLOMEJZZyW ZKJvgDfC+uCxyAXb8OAukY70RZe9xv54iDS8YvHTs+BD2Kw4+Djt0k5guIpEIaphJd PqfpTWKM+zX7Vg1TycNejVuLiXF8lNnf2GCknigQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jann Horn , Suren Baghdasaryan , Todd Kjos , "Joel Fernandes (Google)" Subject: [PATCH 4.4 086/113] staging: android: ashmem: Disallow ashmem memory from being remapped Date: Thu, 27 Feb 2020 14:36:42 +0100 Message-Id: <20200227132225.514339915@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200227132211.791484803@linuxfoundation.org> References: <20200227132211.791484803@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Suren Baghdasaryan commit 6d67b0290b4b84c477e6a2fc6e005e174d3c7786 upstream. When ashmem file is mmapped, the resulting vma->vm_file points to the backing shmem file with the generic fops that do not check ashmem permissions like fops of ashmem do. If an mremap is done on the ashmem region, then the permission checks will be skipped. Fix that by disallowing mapping operation on the backing shmem file. Reported-by: Jann Horn Signed-off-by: Suren Baghdasaryan Cc: stable # 4.4,4.9,4.14,4.18,5.4 Signed-off-by: Todd Kjos Reviewed-by: Joel Fernandes (Google) Link: https://lore.kernel.org/r/20200127235616.48920-1-tkjos@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/staging/android/ashmem.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) --- a/drivers/staging/android/ashmem.c +++ b/drivers/staging/android/ashmem.c @@ -357,8 +357,23 @@ static inline vm_flags_t calc_vm_may_fla _calc_vm_trans(prot, PROT_EXEC, VM_MAYEXEC); } +static int ashmem_vmfile_mmap(struct file *file, struct vm_area_struct *vma) +{ + /* do not allow to mmap ashmem backing shmem file directly */ + return -EPERM; +} + +static unsigned long +ashmem_vmfile_get_unmapped_area(struct file *file, unsigned long addr, + unsigned long len, unsigned long pgoff, + unsigned long flags) +{ + return current->mm->get_unmapped_area(file, addr, len, pgoff, flags); +} + static int ashmem_mmap(struct file *file, struct vm_area_struct *vma) { + static struct file_operations vmfile_fops; struct ashmem_area *asma = file->private_data; int ret = 0; @@ -399,6 +414,19 @@ static int ashmem_mmap(struct file *file } vmfile->f_mode |= FMODE_LSEEK; asma->file = vmfile; + /* + * override mmap operation of the vmfile so that it can't be + * remapped which would lead to creation of a new vma with no + * asma permission checks. Have to override get_unmapped_area + * as well to prevent VM_BUG_ON check for f_ops modification. + */ + if (!vmfile_fops.mmap) { + vmfile_fops = *vmfile->f_op; + vmfile_fops.mmap = ashmem_vmfile_mmap; + vmfile_fops.get_unmapped_area = + ashmem_vmfile_get_unmapped_area; + } + vmfile->f_op = &vmfile_fops; } get_file(asma->file);