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=unavailable 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 749AFC52D35 for ; Thu, 27 Feb 2020 14:03:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 48DC020801 for ; Thu, 27 Feb 2020 14:03:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582812188; bh=m2kCbEicXJNKO8R5aEY0xA0V8g/smXFnErYXcPaD4io=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=YhalGxdvn56f20LmHFstFjOSP0Ieh713nca9cLVbb81qYIhLr39oUVoP/lPnsZCL9 uRFMigROs+xX0pZqEUXCT1byZ3eZ/4PfNKpURengclmmhKaDD00Zk6qIymVfjdgJfT RnkLDJzTei32jinfyrK2gKM3tjEOHkcsoDQIq+lc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733261AbgB0ODG (ORCPT ); Thu, 27 Feb 2020 09:03:06 -0500 Received: from mail.kernel.org ([198.145.29.99]:38086 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733253AbgB0ODD (ORCPT ); Thu, 27 Feb 2020 09:03:03 -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 756B621556; Thu, 27 Feb 2020 14:03:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582812182; bh=m2kCbEicXJNKO8R5aEY0xA0V8g/smXFnErYXcPaD4io=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UCpmA4Oqli+kq2/BBMadIcztGLkNEftWV24FwagbgJ3JKqsHhAVgmJmMfEGqmo0dj 6bZGv9C7le70KZKCOFcCyxCvCEThKR7BzQWj5TG+PvZQAhKKr9FBQm2DJTa1Uk+kdI MEUxqCnUxrHYZqZ5VgK4MzUn+PAipq36LROu7JuI= 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 4.19 17/97] staging: android: ashmem: Disallow ashmem memory from being remapped Date: Thu, 27 Feb 2020 14:36:25 +0100 Message-Id: <20200227132217.437325823@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200227132214.553656188@linuxfoundation.org> References: <20200227132214.553656188@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 @@ -350,8 +350,23 @@ 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; @@ -392,6 +407,19 @@ 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);