[PATCH v3 0/4] LTP reproducer on broken IMA on overlayfs

[PATCH v3 0/4] LTP reproducer on broken IMA on overlayfs

[Petr Vorel]

Hi Mimi, Ignaz,

sorry for bothering you with one more version of this patchset.

Changes v2->v3:
* added one commit "ima/ima_measurements.sh: Require builtin IMA tcb policy"
to avoid false positives 
* added README.md in last commit (might be in separate commit)

Petr Vorel (4):
  ima: Call test's cleanup inside ima_setup.sh cleanup
  shell: Add $TST_DEVICE as default parameter to tst_umount
  ima/ima_measurements.sh: Require builtin IMA tcb policy
  ima: Add overlay test + doc

 doc/test-writing-guidelines.txt               |  4 +-
 runtest/ima                                   |  1 +
 testcases/commands/df/df01.sh                 |  7 +-
 testcases/commands/mkfs/mkfs01.sh             |  2 +-
 .../security/integrity/ima/tests/README.md    | 82 ++++++++++++++++
 .../integrity/ima/tests/evm_overlay.sh        | 94 +++++++++++++++++++
 .../integrity/ima/tests/ima_measurements.sh   |  3 +-
 .../security/integrity/ima/tests/ima_setup.sh | 12 ++-
 .../integrity/ima/tests/ima_violations.sh     |  2 -
 testcases/lib/tst_test.sh                     |  2 +-
 10 files changed, 192 insertions(+), 17 deletions(-)
 create mode 100644 testcases/kernel/security/integrity/ima/tests/README.md
 create mode 100755 testcases/kernel/security/integrity/ima/tests/evm_overlay.sh

-- 
2.21.0

[PATCH v3 1/4] ima: Call test's cleanup inside ima_setup.sh cleanup

[Petr Vorel]

to work the same way as setup

Acked-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
 testcases/kernel/security/integrity/ima/tests/ima_setup.sh  | 6 +++++-
 .../kernel/security/integrity/ima/tests/ima_violations.sh   | 2 --
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/testcases/kernel/security/integrity/ima/tests/ima_setup.sh b/testcases/kernel/security/integrity/ima/tests/ima_setup.sh
index 52551190a..cbded42c2 100644
--- a/testcases/kernel/security/integrity/ima/tests/ima_setup.sh
+++ b/testcases/kernel/security/integrity/ima/tests/ima_setup.sh
@@ -20,7 +20,8 @@
 TST_TESTFUNC="test"
 TST_SETUP_CALLER="$TST_SETUP"
 TST_SETUP="ima_setup"
-TST_CLEANUP="${TST_CLEANUP:-ima_cleanup}"
+TST_CLEANUP_CALLER="$TST_CLEANUP"
+TST_CLEANUP="ima_cleanup"
 TST_NEEDS_TMPDIR=1
 TST_NEEDS_ROOT=1
 
@@ -95,6 +96,9 @@ ima_setup()
 ima_cleanup()
 {
 	local dir
+
+	[ -n "$TST_CLEANUP_CALLER" ] && $TST_CLEANUP_CALLER
+
 	for dir in $UMOUNT; do
 		umount $dir
 	done
diff --git a/testcases/kernel/security/integrity/ima/tests/ima_violations.sh b/testcases/kernel/security/integrity/ima/tests/ima_violations.sh
index 74223c221..a44bd1230 100755
--- a/testcases/kernel/security/integrity/ima/tests/ima_violations.sh
+++ b/testcases/kernel/security/integrity/ima/tests/ima_violations.sh
@@ -51,8 +51,6 @@ cleanup()
 {
 	[ "$PRINTK_RATE_LIMIT" != "0" ] && \
 		sysctl -wq kernel.printk_ratelimit=$PRINTK_RATE_LIMIT
-
-	ima_cleanup
 }
 
 open_file_read()
-- 
2.21.0

[PATCH v3 2/4] shell: Add $TST_DEVICE as default parameter to tst_umount

[Petr Vorel]

+ use it directly as a cleanup function in df01.sh

Acked-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
 doc/test-writing-guidelines.txt                            | 4 ++--
 testcases/commands/df/df01.sh                              | 7 +------
 testcases/commands/mkfs/mkfs01.sh                          | 2 +-
 testcases/kernel/security/integrity/ima/tests/ima_setup.sh | 2 +-
 testcases/lib/tst_test.sh                                  | 2 +-
 5 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/doc/test-writing-guidelines.txt b/doc/test-writing-guidelines.txt
index f1912dc12..fc64b418b 100644
--- a/doc/test-writing-guidelines.txt
+++ b/doc/test-writing-guidelines.txt
@@ -2115,8 +2115,8 @@ The 'tst_mount' mounts '$TST_DEVICE' of '$TST_FS_TYPE' (optional) to
 '$TST_MNT_PARAMS'. The '$TST_MNTPOINT' directory is created if it didn't
 exist prior to the function call.
 
-If the path passed to the 'tst_umount' is not mounted (present in '/proc/mounts')
-it's noop.
+If the path passed (optional, defaults to '$TST_DEVICE') to the 'tst_umount' is
+not mounted (present in '/proc/mounts') it's noop.
 Otherwise it retries to umount the filesystem a few times on a failure, which
 is a workaround since there are a daemons dumb enough to probe all newly
 mounted filesystems, which prevents them from umounting shortly after they
diff --git a/testcases/commands/df/df01.sh b/testcases/commands/df/df01.sh
index 9b0be76fe..3876816dc 100755
--- a/testcases/commands/df/df01.sh
+++ b/testcases/commands/df/df01.sh
@@ -18,7 +18,7 @@
 
 TST_CNT=12
 TST_SETUP=setup
-TST_CLEANUP=cleanup
+TST_CLEANUP=tst_umount
 TST_TESTFUNC=test
 TST_OPTS="f:"
 TST_USAGE=usage
@@ -54,11 +54,6 @@ setup()
 	DF_FS_TYPE=$(mount | grep "$TST_DEVICE" | awk '{print $5}')
 }
 
-cleanup()
-{
-	tst_umount $TST_DEVICE
-}
-
 df_test()
 {
 	local cmd="$1 -P"
diff --git a/testcases/commands/mkfs/mkfs01.sh b/testcases/commands/mkfs/mkfs01.sh
index 88f7f0baa..28af890b3 100755
--- a/testcases/commands/mkfs/mkfs01.sh
+++ b/testcases/commands/mkfs/mkfs01.sh
@@ -71,7 +71,7 @@ mkfs_verify_size()
 {
 	tst_mount
 	local blocknum=`df -P -B 1k mntpoint | tail -n1 | awk '{print $2}'`
-	tst_umount "$TST_DEVICE"
+	tst_umount
 
 	if [ $blocknum -gt "$2" ]; then
 		return 1
diff --git a/testcases/kernel/security/integrity/ima/tests/ima_setup.sh b/testcases/kernel/security/integrity/ima/tests/ima_setup.sh
index cbded42c2..da49eb1b2 100644
--- a/testcases/kernel/security/integrity/ima/tests/ima_setup.sh
+++ b/testcases/kernel/security/integrity/ima/tests/ima_setup.sh
@@ -105,7 +105,7 @@ ima_cleanup()
 
 	if [ "$TST_NEEDS_DEVICE" = 1 ]; then
 		cd $TST_TMPDIR
-		tst_umount $TST_DEVICE
+		tst_umount
 	fi
 }
 
diff --git a/testcases/lib/tst_test.sh b/testcases/lib/tst_test.sh
index 512732315..740253df1 100644
--- a/testcases/lib/tst_test.sh
+++ b/testcases/lib/tst_test.sh
@@ -259,7 +259,7 @@ tst_mount()
 
 tst_umount()
 {
-	local device="$1"
+	local device="${1:-$TST_DEVICE}"
 	local i=0
 
 	if ! grep -q "$device" /proc/mounts; then
-- 
2.21.0

[PATCH v3 3/4] ima/ima_measurements.sh: Require builtin IMA tcb policy

[Petr Vorel]

Although custom policy which contains tcb can be loaded via dracut,
systemd or later manually from user space, detecting it would require
IMA_READ_POLICY=y. In order to simplify the check and avoid false
positives lets ignore this option and require builtin IMA tcb policy.

Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
 .../kernel/security/integrity/ima/tests/ima_measurements.sh    | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/testcases/kernel/security/integrity/ima/tests/ima_measurements.sh b/testcases/kernel/security/integrity/ima/tests/ima_measurements.sh
index 328affc43..a3aa24d8a 100755
--- a/testcases/kernel/security/integrity/ima/tests/ima_measurements.sh
+++ b/testcases/kernel/security/integrity/ima/tests/ima_measurements.sh
@@ -57,7 +57,8 @@ setup()
 	[ -z "$DIGEST_INDEX" ] && tst_brk TCONF \
 		"Cannot find digest index (template: '$template')"
 
-	tst_res TINFO "IMA measurement tests assume tcb policy to be loaded (ima_policy=tcb)"
+	grep -q -e ima_policy=[a-z_]*tcb -e ima_tcb -e ima_appraise_tcb /proc/cmdline || \
+		tst_brk TCONF "IMA measurement tests require builtin IMA tcb policy (ima_policy=tcb or ima_policy=appraise_tcb kernel parameter)"
 }
 
 # TODO: find support for rmd128 rmd256 rmd320 wp256 wp384 tgr128 tgr160
-- 
2.21.0

[PATCH v3 4/4] ima: Add overlay test + doc

[Petr Vorel]

test demonstrate a bug on overlayfs on current mainline kernel when
combining IMA with EVM.

Based on reproducer made by Ignaz Forster <iforster@suse.de>
used for not upstreamed patchset [1] and previous report [2].
IMA only behavior has already been fixed [3].

NOTE: backup variables are needed because ima_setup.sh calling
tst_mount as well when TMPDIR is on tmpfs device.

Documentation is based on Ignaz Forster instructions for openSUSE [4].

[1] https://www.spinics.net/lists/linux-integrity/msg05926.html
[2] https://www.spinics.net/lists/linux-integrity/msg03593.html
[3] https://patchwork.kernel.org/patch/10776231/
[4] http://lists.linux.it/pipermail/ltp/2019-May/011956.html

Tested-by: Ignaz Forster <iforster@suse.de>
Acked-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
Ignaz, you specified in [4] ima_appraise=appraise_tcb. IMHO this option
for ima_appraise does not exist. It works "triggers bug" for me without it.

Mimi, can you have a brief look on docs?

Kind regards,
Petr
---
 runtest/ima                                   |  1 +
 .../security/integrity/ima/tests/README.md    | 82 ++++++++++++++++
 .../integrity/ima/tests/evm_overlay.sh        | 94 +++++++++++++++++++
 .../security/integrity/ima/tests/ima_setup.sh |  4 +-
 4 files changed, 179 insertions(+), 2 deletions(-)
 create mode 100644 testcases/kernel/security/integrity/ima/tests/README.md
 create mode 100755 testcases/kernel/security/integrity/ima/tests/evm_overlay.sh

diff --git a/runtest/ima b/runtest/ima
index bcae16bb7..f3ea88cf0 100644
--- a/runtest/ima
+++ b/runtest/ima
@@ -3,3 +3,4 @@ ima_measurements ima_measurements.sh
 ima_policy ima_policy.sh
 ima_tpm ima_tpm.sh
 ima_violations ima_violations.sh
+evm_overlay evm_overlay.sh
diff --git a/testcases/kernel/security/integrity/ima/tests/README.md b/testcases/kernel/security/integrity/ima/tests/README.md
new file mode 100644
index 000000000..e1d106c0f
--- /dev/null
+++ b/testcases/kernel/security/integrity/ima/tests/README.md
@@ -0,0 +1,82 @@
+IMA + EVM testing
+=================
+
+IMA tests
+---------
+
+`ima_measurements.sh` require builtin IMA tcb policy to be loaded
+(`ima_policy=tcb` or `ima_policy=appraise_tcb` kernel parameter).
+Although custom policy which contains tcb can be loaded via dracut,
+systemd or later manually from user space, detecting it would require
+`IMA_READ_POLICY=y` therefore ignore this option.
+
+Mandatory kernel configuration for IMA:
+```
+CONFIG_INTEGRITY=y
+CONFIG_IMA=y
+```
+
+EVM tests
+---------
+
+`evm_overlay.sh` requires to builtin IMA appraise tcb policy (`ima_policy=appraise_tcb`
+kernel parameter) which appraises the integrity of all files owned by root.  and EVM setup.
+Again, for simplicity ignore possibility to have IMA appraise tcb policy loaded in custom policy.
+
+Mandatory kernel configuration for IMA & EVM:
+```
+CONFIG_INTEGRITY=y
+CONFIG_INTEGRITY_SIGNATURE=y
+CONFIG_IMA=y
+CONFIG_IMA_APPRAISE=y
+CONFIG_EVM=y
+CONFIG_KEYS=y
+CONFIG_TRUSTED_KEYS=y
+CONFIG_ENCRYPTED_KEYS=y
+```
+
+Example of installing IMA + EVM on openSUSE:
+
+* Boot install system with `ima_policy=appraise_tcb ima_appraise=fix evm=fix` kernel parameters
+  (for IMA measurement, IMA appraisal and EVM protection)
+* Proceed with installation until summary screen, but do not start the installation yet
+* Select package `dracut-ima` (required for early boot EVM support) for installation
+  (Debian based distros already contain IMA + EVM support in `dracut` package)
+* Change to a console window and run commands to generate keys required by EVM:
+```
+# mkdir /etc/keys
+# user_key=$(keyctl add user kmk-user "`dd if=/dev/urandom bs=1 count=32 2>/dev/null`" @u)
+# keyctl pipe "$user_key" > /etc/keys/kmk-user.blob
+# evm_key=$(keyctl add encrypted evm-key "new user:kmk-user 64" @u)
+# keyctl pipe "$evm_key" >/etc/keys/evm.blob
+# cat <<END >/etc/sysconfig/masterkey
+MASTERKEYTYPE="user"
+MASTERKEY="/etc/keys/kmk-user.blob"
+END
+# cat <<END >/etc/sysconfig/evm
+EVMKEY="/etc/keys/evm.blob"
+END
+# mount -t securityfs security /sys/kernel/security
+# echo 1 >/sys/kernel/security/evm
+```
+
+* Go back to the installation summary screen and start the installation
+* During the installation execute the following commands from the console:
+```
+# cp -r /etc/keys /mnt/etc/ # Debian based distributions: use /target instead of /mnt
+# cp /etc/sysconfig/{evm,masterkey} /mnt/etc/sysconfig/
+```
+
+This should work on any distribution using dracut.
+Loading EVM keys is also possible with initramfs-tools (Debian based distributions).
+
+Of course it's possible to install OS usual way, add keys later and fix missing xattrs with:
+```
+evmctl -r ima_fix /
+```
+
+or with `find` if evmctl not available:
+```
+find / \( -fstype rootfs -o -fstype ext4 -o -fstype btrfs -o -fstype xfs \) -exec sh -c "< '{}'" \;
+```
+Again, fixing requires `ima_policy=appraise_tcb ima_appraise=fix evm=fix` kernel parameters.
diff --git a/testcases/kernel/security/integrity/ima/tests/evm_overlay.sh b/testcases/kernel/security/integrity/ima/tests/evm_overlay.sh
new file mode 100755
index 000000000..054b19428
--- /dev/null
+++ b/testcases/kernel/security/integrity/ima/tests/evm_overlay.sh
@@ -0,0 +1,94 @@
+#!/bin/sh
+# Copyright (c) 2019 Petr Vorel <pvorel@suse.cz>
+# Based on reproducer and further discussion with Ignaz Forster <iforster@suse.de>
+# Reproducer for not upstreamed patchset [1] and previous report [2].
+# [1] https://www.spinics.net/lists/linux-integrity/msg05926.html
+# [2] https://www.spinics.net/lists/linux-integrity/msg03593.html
+
+TST_SETUP="setup"
+TST_CLEANUP="cleanup"
+TST_NEEDS_DEVICE=1
+TST_CNT=4
+. ima_setup.sh
+
+setup()
+{
+	EVM_FILE="/sys/kernel/security/evm"
+
+	[ -f "$EVM_FILE" ] || tst_brk TCONF "EVM not enabled in kernel"
+	[ $(cat $EVM_FILE) -eq 1 ] || tst_brk TCONF "EVM not enabled for this boot"
+
+	grep -q -e appraise_tcb /proc/cmdline || \
+		tst_brk TCONF "Test requires specify IMA builtin appraise policy as kernel parameter"
+
+	lower="$TST_MNTPOINT/lower"
+	upper="$TST_MNTPOINT/upper"
+	work="$TST_MNTPOINT/work"
+	merged="$TST_MNTPOINT/merged"
+	mkdir -p $lower $upper $work $merged
+
+	device_backup="$TST_DEVICE"
+	TST_DEVICE="overlay"
+
+	fs_type_backup="$TST_FS_TYPE"
+	TST_FS_TYPE="overlay"
+
+	mntpoint_backup="$TST_MNTPOINT"
+	TST_MNTPOINT="$merged"
+
+	params_backup="$TST_MNT_PARAMS"
+	TST_MNT_PARAMS="-o lowerdir=$lower,upperdir=$upper,workdir=$work"
+
+	tst_mount
+	mounted=1
+}
+
+test1()
+{
+	local file="foo1.txt"
+
+	tst_res TINFO "overwrite file in overlay"
+	EXPECT_PASS echo lower \> $lower/$file
+	EXPECT_PASS echo overlay \> $merged/$file
+}
+
+test2()
+{
+	local file="foo2.txt"
+
+	tst_res TINFO "append file in overlay"
+	EXPECT_PASS echo lower \> $lower/$file
+	EXPECT_PASS echo overlay \>\> $merged/$file
+}
+
+test3()
+{
+	local file="foo3.txt"
+
+	tst_res TINFO "create a new file in overlay"
+	EXPECT_PASS echo overlay \> $merged/$file
+}
+
+test4()
+{
+	local f
+
+	tst_res TINFO "read all created files"
+	for f in $(find $TST_MNTPOINT -type f); do
+		EXPECT_PASS cat $f \> /dev/null 2\> /dev/null
+	done
+}
+
+cleanup()
+{
+	[ -n "$mounted" ] || return 0
+
+	tst_umount $TST_DEVICE
+
+	TST_DEVICE="$device_backup"
+	TST_FS_TYPE="$fs_type_backup"
+	TST_MNTPOINT="$mntpoint_backup"
+	TST_MNT_PARAMS="$params_backup"
+}
+
+tst_run
diff --git a/testcases/kernel/security/integrity/ima/tests/ima_setup.sh b/testcases/kernel/security/integrity/ima/tests/ima_setup.sh
index da49eb1b2..08aa5300a 100644
--- a/testcases/kernel/security/integrity/ima/tests/ima_setup.sh
+++ b/testcases/kernel/security/integrity/ima/tests/ima_setup.sh
@@ -64,14 +64,14 @@ print_ima_config()
 	local config="/boot/config-$(uname -r)"
 	local i
 
-	tst_res TINFO "/proc/cmdline: $(cat /proc/cmdline)"
-
 	if [ -r "$config" ]; then
 		tst_res TINFO "IMA kernel config:"
 		for i in $(grep ^CONFIG_IMA $config); do
 			tst_res TINFO "$i"
 		done
 	fi
+
+	tst_res TINFO "/proc/cmdline: $(cat /proc/cmdline)"
 }
 
 ima_setup()
-- 
2.21.0

Re: [PATCH v3 3/4] ima/ima_measurements.sh: Require builtin IMA tcb policy

[Mimi Zohar]

Hi Petr,

On Tue, 2019-06-11 at 21:30 +0200, Petr Vorel wrote:
> Although custom policy which contains tcb can be loaded via dracut,

^which may contain the equivalent measurement tcb rules

> systemd or later manually from user space, detecting it would require
> IMA_READ_POLICY=y. In order to simplify the check and avoid false
> positives lets ignore this option and require builtin IMA tcb policy.

This test is for adding new measurements to the measurement list.

> 
> Signed-off-by: Petr Vorel <pvorel@suse.cz>
> ---
>  .../kernel/security/integrity/ima/tests/ima_measurements.sh    | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/testcases/kernel/security/integrity/ima/tests/ima_measurements.sh b/testcases/kernel/security/integrity/ima/tests/ima_measurements.sh
> index 328affc43..a3aa24d8a 100755
> --- a/testcases/kernel/security/integrity/ima/tests/ima_measurements.sh
> +++ b/testcases/kernel/security/integrity/ima/tests/ima_measurements.sh
> @@ -57,7 +57,8 @@ setup()
>  	[ -z "$DIGEST_INDEX" ] && tst_brk TCONF \
>  		"Cannot find digest index (template: '$template')"
> 
> -	tst_res TINFO "IMA measurement tests assume tcb policy to be loaded (ima_policy=tcb)"
> +	grep -q -e ima_policy=[a-z_]*tcb -e ima_tcb -e ima_appraise_tcb /proc/cmdline || \
> +		tst_brk TCONF "IMA measurement tests require builtin IMA tcb policy (ima_policy=tcb or ima_policy=appraise_tcb kernel parameter)"
>  }
> 

"appraise_tcb" doesn't provide the necessary measurement rules.
"ima_policy=" isn't order specific.  The check would be for "|tcb", "|
tcb", "tcb|", "tcb |", or just "=tcb".  The deprecated "ima_tcb"
option is fine too.

Mimi

>  # TODO: find support for rmd128 rmd256 rmd320 wp256 wp384 tgr128 tgr160

Re: [PATCH v3 3/4] ima/ima_measurements.sh: Require builtin IMA tcb policy

[Petr Vorel]

Hi Mimi,

thanks a lot for your review.

> On Tue, 2019-06-11 at 21:30 +0200, Petr Vorel wrote:
> > Although custom policy which contains tcb can be loaded via dracut,

> ^which may contain the equivalent measurement tcb rules
I'm going to address this in v4.

> > systemd or later manually from user space, detecting it would require
> > IMA_READ_POLICY=y. In order to simplify the check and avoid false
> > positives lets ignore this option and require builtin IMA tcb policy.

> This test is for adding new measurements to the measurement list.
Sure. So what should I change in commit message?


> > Signed-off-by: Petr Vorel <pvorel@suse.cz>
> > ---
> >  .../kernel/security/integrity/ima/tests/ima_measurements.sh    | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)

> > diff --git a/testcases/kernel/security/integrity/ima/tests/ima_measurements.sh b/testcases/kernel/security/integrity/ima/tests/ima_measurements.sh
> > index 328affc43..a3aa24d8a 100755
> > --- a/testcases/kernel/security/integrity/ima/tests/ima_measurements.sh
> > +++ b/testcases/kernel/security/integrity/ima/tests/ima_measurements.sh
> > @@ -57,7 +57,8 @@ setup()
> >  	[ -z "$DIGEST_INDEX" ] && tst_brk TCONF \
> >  		"Cannot find digest index (template: '$template')"

> > -	tst_res TINFO "IMA measurement tests assume tcb policy to be loaded (ima_policy=tcb)"
> > +	grep -q -e ima_policy=[a-z_]*tcb -e ima_tcb -e ima_appraise_tcb /proc/cmdline || \
> > +		tst_brk TCONF "IMA measurement tests require builtin IMA tcb policy (ima_policy=tcb or ima_policy=appraise_tcb kernel parameter)"
> >  }


> "appraise_tcb" doesn't provide the necessary measurement rules.
> "ima_policy=" isn't order specific.  The check would be for "|tcb", "|
> tcb", "tcb|", "tcb |", or just "=tcb".  The deprecated "ima_tcb"
> option is fine too.
Going to change in v4.

> Mimi

Kind regards,
Petr