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=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY 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 0ACB9C433E0 for ; Sun, 17 May 2020 15:55:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DE17920709 for ; Sun, 17 May 2020 15:55:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728004AbgEQPzJ (ORCPT ); Sun, 17 May 2020 11:55:09 -0400 Received: from out20-75.mail.aliyun.com ([115.124.20.75]:45439 "EHLO out20-75.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727979AbgEQPzJ (ORCPT ); Sun, 17 May 2020 11:55:09 -0400 X-Alimail-AntiSpam: AC=CONTINUE;BC=0.07449396|-1;CH=green;DM=|CONTINUE|false|;DS=CONTINUE|ham_system_inform|0.0118988-0.000837333-0.987264;FP=0|0|0|0|0|-1|-1|-1;HT=e02c03279;MF=guan@eryu.me;NM=1;PH=DS;RN=2;RT=2;SR=0;TI=SMTPD_---.HZsh76H_1589730905; Received: from localhost(mailfrom:guan@eryu.me fp:SMTPD_---.HZsh76H_1589730905) by smtp.aliyun-inc.com(10.147.40.200); Sun, 17 May 2020 23:55:05 +0800 Date: Sun, 17 May 2020 23:55:05 +0800 From: Eryu Guan To: Eric Sandeen Cc: fstests Subject: Re: [PATCH 2/3] fstests: test restricted symlinks & hardlinks sysctls Message-ID: <20200517155505.GD2704@desktop> References: <99a3164b-ee00-113c-e0aa-41eab9633364@redhat.com> <294c5739-ff30-285c-8cf7-11a6dff98294@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <294c5739-ff30-285c-8cf7-11a6dff98294@redhat.com> Sender: fstests-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: fstests@vger.kernel.org On Tue, May 05, 2020 at 03:20:10PM -0500, Eric Sandeen wrote: > This tests the fs.protected_symlinks and fs.protected_hardlinks > sysctls which restrict links behavior in sticky world-writable > directories as documented in the kernel at > Documentation/admin-guide/sysctl/fs.rst > > Signed-off-by: Eric Sandeen > --- > > diff --git a/tests/generic/900 b/tests/generic/900 > new file mode 100755 > index 00000000..f0ac46ef > --- /dev/null > +++ b/tests/generic/900 > @@ -0,0 +1,114 @@ > +#! /bin/bash > +# SPDX-License-Identifier: GPL-2.0 > +# Copyright (c) 2020 Red Hat, Inc. All Rights Reserved. > +# > +# FS QA Test 900 > +# > +# Test protected_symlink and protected_hardlink ioctls > +# > +seq=`basename $0` > +seqres=$RESULT_DIR/$seq > +echo "QA output created by $seq" > + > +here=`pwd` > +tmp=/tmp/$$ > +status=1 # failure is the default! > +trap "_cleanup; exit \$status" 0 1 2 3 15 > + > +_cleanup() > +{ > + rm -rf $TEST_DIR/$seq > + sysctl -qw fs.protected_symlinks=$SYMLINK_PROTECTION > + sysctl -qw fs.protected_hardlinks=$HARDLINK_PROTECTION Restore the sysctl only if "SYMLINK_PROTECTION" and "HARDLINK_PROTECTION" are set. > + cd / > + rm -f $tmp.* > +} > + > +# get standard environment, filters and checks > +. ./common/rc > +. ./common/filter > + > +# remove previous $seqres.full before test > +rm -f $seqres.full > + > +# real QA test starts here > + > +# Modify as appropriate. > +_supported_fs generic > +_supported_os Linux > +_require_test > +_require_sysctl fs.protected_symlinks > +_require_sysctl fs.protected_hardlinks > +_require_user fsgqa > +_require_user fsgqa2 New user :) update README as well? > + > +OWNER=fsgqa > +OTHER=fsgqa2 > + > +# Save current system state to reset when done > +SYMLINK_PROTECTION=`sysctl -n fs.protected_symlinks` > +HARDLINK_PROTECTION=`sysctl -n fs.protected_hardlinks` > + > +test_symlink() > +{ > + ln -s $TEST_DIR/$seq/target $TEST_DIR/$seq/sticky_dir/symlink > + chown $OTHER.$OTHER $TEST_DIR/$seq/sticky_dir > + chown $OWNER.$OWNER $TEST_DIR/$seq/sticky_dir/symlink > + # If we can read the target, we followed the link > + sudo -u $OTHER cat $TEST_DIR/$seq/sticky_dir/symlink 2>&1 \ Use _user_do instead of sudo? > + | _filter_test_dir > + rm -f $TEST_DIR/$seq/sticky_dir/symlink > +} > + > +test_hardlink() > +{ > + chown $OWNER.$OWNER $TEST_DIR/$seq/target > + chmod go-rw $TEST_DIR/$seq/target > + sudo -u $OTHER \ > + ln $TEST_DIR/$seq/target $TEST_DIR/$seq/sticky_dir/hardlink 2>&1 \ > + | _filter_test_dir Same here. Thanks, Eryu > + test -f $TEST_DIR/$seq/sticky_dir/hardlink \ > + && echo "successfully created hardlink" > + rm -f $TEST_DIR/$seq/sticky_dir/hardlink > +} > + > +setup_tree() > +{ > + # Create world-writable sticky dir > + mkdir -p $TEST_DIR/$seq/sticky_dir > + chmod 1777 $TEST_DIR/$seq/sticky_dir > + # And a file elsewhere that will be linked to from that sticky dir > + mkdir -p $TEST_DIR/$seq > + # If we can read it, we followed the link. > + echo "successfully followed symlink" > $TEST_DIR/$seq/target > +} > + > +setup_tree > + > +# First test fs.protected_symlinks > +# With protection on, symlink follows should fail if the > +# link owner != the sticky directory owner, and the process > +# is not the link owner. > +echo "== Test symlink follow protection when" > +echo "== process != link owner and dir owner != link owner" > +sysctl -w fs.protected_symlinks=0 > +test_symlink > +sysctl -w fs.protected_symlinks=1 > +test_symlink > + > +echo > + > +# Now test fs.protected_hardlinks > +# With protection on, hardlink creation should fail if the > +# process does not own the target file, and the process does not have > +# read-write access to the target > +echo "== Test hardlink create protection when" > +echo "== process != target owner and process cannot read target" > +sysctl -w fs.protected_hardlinks=0 > +test_hardlink > +sysctl -w fs.protected_hardlinks=1 > +test_hardlink > + > +# success, all done > +status=0 > +exit > diff --git a/tests/generic/900.out b/tests/generic/900.out > new file mode 100644 > index 00000000..c9b26dbd > --- /dev/null > +++ b/tests/generic/900.out > @@ -0,0 +1,14 @@ > +QA output created by 900 > +== Test symlink follow protection when > +== process != link owner and dir owner != link owner > +fs.protected_symlinks = 0 > +successfully followed symlink > +fs.protected_symlinks = 1 > +cat: TEST_DIR/900/sticky_dir/symlink: Permission denied > + > +== Test hardlink create protection when > +== process != target owner and process cannot read target > +fs.protected_hardlinks = 0 > +successfully created hardlink > +fs.protected_hardlinks = 1 > +ln: failed to create hard link 'TEST_DIR/900/sticky_dir/hardlink' => 'TEST_DIR/900/target': Operation not permitted > diff --git a/tests/generic/group b/tests/generic/group > index 718575ba..782b0cc3 100644 > --- a/tests/generic/group > +++ b/tests/generic/group > @@ -598,3 +598,4 @@ > 594 auto quick quota > 595 auto quick encrypt > 596 auto quick > +900 auto quick perms >