[LTP] [PATCH 3/3] IMA: Add a test to verify measurement of certificate imported into a keyring

Lachlan Sneff
2020-08-03T18:47:26Z

The IMA subsystem supports measuring certificates that have been
imported into either system built-in or user-defined keyrings.
A test to verify measurement of a certificate imported
into a keyring is required.

Add an IMA measurement test that verifies that an x509 certificate
can be imported into a newly-created, user-defined keyring and measured
correctly by the IMA subsystem.

A certificate used by the test is included in the `datafiles/keys`
directory.

There can be restrictions on importing a certificate into a builtin
trusted keyring. For example, the `.ima` keyring requires that
imported certs be signed by a kernel private key in certain
kernel configurations. For this reason, this test defines
a user-defined keyring and imports a certificate into that.

Signed-off-by: Lachlan Sneff <t-josne@linux.microsoft.com>
---
.../kernel/security/integrity/ima/README.md | 14 ++++++
.../security/integrity/ima/datafiles/Makefile | 2 +-
.../integrity/ima/datafiles/keys/Makefile | 15 ++++++
.../integrity/ima/datafiles/keys/x509_ima.der | Bin 0 -> 650 bytes
.../security/integrity/ima/tests/ima_keys.sh | 44 +++++++++++++++++-
5 files changed, 72 insertions(+), 3 deletions(-)
create mode 100644 testcases/kernel/security/integrity/ima/datafiles/keys/Makefile
create mode 100644 testcases/kernel/security/integrity/ima/datafiles/keys/x509_ima.der

diff --git a/testcases/kernel/security/integrity/ima/README.md b/testcases/kernel/security/integrity/ima/README.md
index 2956ac7fd..bfa015191 100644
--- a/testcases/kernel/security/integrity/ima/README.md
+++ b/testcases/kernel/security/integrity/ima/README.md
@@ -23,6 +23,20 @@ Mandatory kernel configuration for IMA:
```
CONFIG_IMA_READ_POLICY=y
```
+The certificate import test in `ima_keys.sh` also requires that
+the `key_import_test` keyring is specified in the IMA policy.
+
+One way to do this is to modify an existing KEY_CHECK entry
+in the IMA policy by adding `key_import_test` for keyrings:
+```
+measure func=KEY_CHECK keyrings=.ima|.evm|key_import_test template=ima-buf
+```
+
+If KEY_CHECK entry does not exist in the IMA policy then by adding
+the following line:
+```
+measure func=KEY_CHECK keyrings=key_import_test template=ima-buf
+```

### IMA kexec test

diff --git a/testcases/kernel/security/integrity/ima/datafiles/Makefile b/testcases/kernel/security/integrity/ima/datafiles/Makefile
index 3772e9a03..4b4c46b82 100644
--- a/testcases/kernel/security/integrity/ima/datafiles/Makefile
+++ b/testcases/kernel/security/integrity/ima/datafiles/Makefile
@@ -24,6 +24,6 @@ top_srcdir ?= ../../../../../..

include $(top_srcdir)/include/mk/env_pre.mk

-SUBDIRS := policy
+SUBDIRS := policy keys

include $(top_srcdir)/include/mk/generic_trunk_target.mk
diff --git a/testcases/kernel/security/integrity/ima/datafiles/keys/Makefile b/testcases/kernel/security/integrity/ima/datafiles/keys/Makefile
new file mode 100644
index 000000000..a8ab7a1b5
--- /dev/null
+++ b/testcases/kernel/security/integrity/ima/datafiles/keys/Makefile
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (c) 2020 Microsoft Corporation
+# Author: Lachlan Sneff <t-josne@linux.microsoft.com>
+#
+# IMA datafiles/keys Makefile
+
+top_srcdir ?= ../../../../../../..
+
+include $(top_srcdir)/include/mk/env_pre.mk
+
+INSTALL_DIR := testcases/data/ima_keys
+
+INSTALL_TARGETS := x509_ima.der
+
+include $(top_srcdir)/include/mk/generic_leaf_target.mk
diff --git a/testcases/kernel/security/integrity/ima/datafiles/keys/x509_ima.der b/testcases/kernel/security/integrity/ima/datafiles/keys/x509_ima.der
new file mode 100644
index 0000000000000000000000000000000000000000..92be058da22adffa9d6b6e51efa0c737ebbbbdcd
GIT binary patch
literal 650
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zbotZ0X`ckHOmaVLm85n@E9hN_K;~PUB>DFAzh(;(UoMln9V>g;W#-LUGS7A`nYQKY
WBem{7L5JThS+;$vggi%(*E;~nlJ80Y

literal 0
HcmV?d00001

diff --git a/testcases/kernel/security/integrity/ima/tests/ima_keys.sh b/testcases/kernel/security/integrity/ima/tests/ima_keys.sh
index 3aea26056..f34f40132 100755
--- a/testcases/kernel/security/integrity/ima/tests/ima_keys.sh
+++ b/testcases/kernel/security/integrity/ima/tests/ima_keys.sh
@@ -6,9 +6,10 @@
#
# Verify that keys are measured correctly based on policy.

-TST_NEEDS_CMDS="cut grep sed tr xxd"
-TST_CNT=1
+TST_NEEDS_CMDS="grep cut sed tr xxd evmctl openssl keyctl"
+TST_CNT=2
TST_NEEDS_DEVICE=1
+TST_NEEDS_ROOT=1

. ima_setup.sh

@@ -58,4 +59,43 @@ test1()
tst_res TPASS "specified keyrings were measured correctly"
}

+# Create a new keyring, import a certificate into it, and verify
+# that the certificate is measured correctly by IMA.
+test2() {
+ local new_keyring_id temp_file="file.txt" \
+ cert_file="$TST_DATAROOT/x509_ima.der"
+
+ if ! check_ima_policy_content '^measure.*func=KEY_CHECK.*keyrings=.*key_import_test'; then
+ tst_brk TCONF "the IMA policy does not include the key_import_test keyring. See the LTP IMA README."
+ fi
+
+ # Assuming this test is executed in a separate shell,
+ # create a new session that will be cleaned up when
+ # the shell exits.
+ keyctl new_session > /dev/null
+
+ new_keyring_id=$(keyctl newring key_import_test @s) || \
+ tst_brk TCONF "unable to create a new keyring"
+
+ tst_is_num "$new_keyring_id" || \
+ tst_brk TCONF "unable to parse the new keyring id"
+
+ evmctl import "$cert_file" "$new_keyring_id" > /dev/null || \
+ tst_brk TCONF "unable to import a cert into a the key_import_test keyring"
+
+ grep "key_import_test" "$ASCII_MEASUREMENTS" | tail -n1 | cut -d' ' -f6 | \
+ xxd -r -p > "$temp_file" || \
+ tst_brk TCONF "keyring not found in $ASCII_MEASUREMENTS"
+
+ if ! openssl x509 -in "$temp_file" -inform der > /dev/null; then
+ tst_brk TCONF "the cert logged in $ASCII_MEASUREMENTS is not a valid x509 certificate"
+ fi
+
+ if cmp -s "$temp_file" "$cert_file"; then
+ tst_res TPASS "logged cert matches original cert"
+ else
+ tst_res TFAIL "logged cert does not match original cert"
+ fi
+}
+
tst_run
--
2.25.1