[PATCH v3 3/4] IMA: Add a test to verify measurement of certificate imported into a keyring

Petr Vorel
2020-08-17T13:09:29Z

From: Lachlan Sneff <t-josne@linux.microsoft.com>

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.

Reviewed-by: Petr Vorel <pvorel@suse.cz>
Signed-off-by: Lachlan Sneff <t-josne@linux.microsoft.com>
[ pvorel: Added key_import_test into keycheck.policy, reword
instructions in README.md, LTP API related fixes ]
Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
The same as v2.

.../kernel/security/integrity/ima/README.md | 12 ++--
.../integrity/ima/datafiles/ima_keys/Makefile | 2 +-
.../ima/datafiles/ima_keys/keycheck.policy | 2 +-
.../ima/datafiles/ima_keys/x509_ima.der | Bin 0 -> 650 bytes
.../security/integrity/ima/tests/ima_keys.sh | 68 +++++++++++++++---
5 files changed, 70 insertions(+), 14 deletions(-)
create mode 100644 testcases/kernel/security/integrity/ima/datafiles/ima_keys/x509_ima.der

diff --git a/testcases/kernel/security/integrity/ima/README.md b/testcases/kernel/security/integrity/ima/README.md
index 392e1e868..68d046678 100644
--- a/testcases/kernel/security/integrity/ima/README.md
+++ b/testcases/kernel/security/integrity/ima/README.md
@@ -16,11 +16,15 @@ space, may contain equivalent measurement tcb rules, detecting them would
require `IMA_READ_POLICY=y` therefore ignore this option.

### IMA key test
-`ima_keys.sh` requires a readable IMA policy, as well as a loaded policy
-with `func=KEY_CHECK keyrings=...`, see example in `keycheck.policy`.
+The measuring keys test (first test) in `ima_keys.sh` requires a readable IMA
+policy, as well as a loaded measure policy with `func=KEY_CHECK keyrings=...`.

-As well as what's required for the IMA tests, the following are also required
--in the kernel configuration:
+The certificate import test (second test) require measure policy with
+`func=KEY_CHECK keyrings=key_import_test`. Valid policy for both is in
+`keycheck.policy`.
+
+As well as what's required for the IMA tests, key tests require reading the IMA
+policy allowed in the kernel configuration:
```
CONFIG_IMA_READ_POLICY=y
```
diff --git a/testcases/kernel/security/integrity/ima/datafiles/ima_keys/Makefile b/testcases/kernel/security/integrity/ima/datafiles/ima_keys/Makefile
index 452321843..ac7ce33ab 100644
--- a/testcases/kernel/security/integrity/ima/datafiles/ima_keys/Makefile
+++ b/testcases/kernel/security/integrity/ima/datafiles/ima_keys/Makefile
@@ -6,6 +6,6 @@ top_srcdir ?= ../../../../../../..
include $(top_srcdir)/include/mk/env_pre.mk

INSTALL_DIR := testcases/data/ima_keys
-INSTALL_TARGETS := *.policy
+INSTALL_TARGETS := *.policy x509_ima.der

include $(top_srcdir)/include/mk/generic_leaf_target.mk
diff --git a/testcases/kernel/security/integrity/ima/datafiles/ima_keys/keycheck.policy b/testcases/kernel/security/integrity/ima/datafiles/ima_keys/keycheck.policy
index 3f1934a3d..623162002 100644
--- a/testcases/kernel/security/integrity/ima/datafiles/ima_keys/keycheck.policy
+++ b/testcases/kernel/security/integrity/ima/datafiles/ima_keys/keycheck.policy
@@ -1 +1 @@
-measure func=KEY_CHECK keyrings=.ima|.evm|.builtin_trusted_keys|.blacklist template=ima-buf
+measure func=KEY_CHECK keyrings=.ima|.evm|.builtin_trusted_keys|.blacklist|key_import_test template=ima-buf
diff --git a/testcases/kernel/security/integrity/ima/datafiles/ima_keys/x509_ima.der b/testcases/kernel/security/integrity/ima/datafiles/ima_keys/x509_ima.der
new file mode 100644
index 0000000000000000000000000000000000000000..92be058da22adffa9d6b6e51efa0c737ebbbbdcd
GIT binary patch
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diff --git a/testcases/kernel/security/integrity/ima/tests/ima_keys.sh b/testcases/kernel/security/integrity/ima/tests/ima_keys.sh
index 53c289054..30950904e 100755
--- a/testcases/kernel/security/integrity/ima/tests/ima_keys.sh
+++ b/testcases/kernel/security/integrity/ima/tests/ima_keys.sh
@@ -6,8 +6,8 @@
#
# Verify that keys are measured correctly based on policy.

-TST_NEEDS_CMDS="cut grep sed tr xxd"
-TST_CNT=1
+TST_NEEDS_CMDS="cmp cut grep sed tr xxd"
+TST_CNT=2
TST_NEEDS_DEVICE=1

. ima_setup.sh
@@ -20,20 +20,22 @@ test1()
local pattern="func=KEY_CHECK"
local test_file="file.txt"

- tst_res TINFO "verifying key measurement for keyrings and templates specified in IMA policy file"
+ tst_res TINFO "verify key measurement for keyrings and templates specified in IMA policy"

require_ima_policy_content "$pattern"
keycheck_lines=$(check_ima_policy_content "$pattern" "")
keycheck_line=$(echo "$keycheck_lines" | grep "keyrings" | head -n1)

if [ -z "$keycheck_line" ]; then
- tst_brk TCONF "ima policy does not specify a keyrings to check"
+ tst_res TCONF "IMA policy does not specify a keyrings to check"
+ return
fi

keyrings=$(echo "$keycheck_line" | tr " " "\n" | grep "keyrings" | \
sed "s/\./\\\./g" | cut -d'=' -f2)
if [ -z "$keyrings" ]; then
- tst_brk TCONF "ima policy has a keyring key-value specifier, but no specified keyrings"
+ tst_res TCONF "IMA policy has a keyring key-value specifier, but no specified keyrings"
+ return
fi

templates=$(echo "$keycheck_line" | tr " " "\n" | grep "template" | \
@@ -49,11 +51,13 @@ test1()

echo "$line" | cut -d' ' -f6 | xxd -r -p > $test_file

- expected_digest="$(compute_digest $algorithm $test_file)" || \
- tst_brk TCONF "cannot compute digest for $algorithm"
+ if ! expected_digest="$(compute_digest $algorithm $test_file)"; then
+ tst_res TCONF "cannot compute digest for $algorithm"
+ return
+ fi

if [ "$digest" != "$expected_digest" ]; then
- tst_res TFAIL "incorrect digest was found for the ($keyring) keyring"
+ tst_res TFAIL "incorrect digest was found for $keyring keyring"
return
fi
done
@@ -61,4 +65,52 @@ 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()
+{
+ tst_require_cmds evmctl keyctl openssl
+
+ local cert_file="$TST_DATAROOT/x509_ima.der"
+ local keyring_name="key_import_test"
+ local temp_file="file.txt"
+ local keyring_id
+
+ tst_res TINFO "verify measurement of certificate imported into a keyring"
+
+ if ! check_ima_policy_content "^measure.*func=KEY_CHECK.*keyrings=.*$keyring_name"; then
+ tst_brk TCONF "IMA policy does not contain $keyring_name keyring"
+ fi
+
+ keyctl new_session > /dev/null
+
+ keyring_id=$(keyctl newring $keyring_name @s) || \
+ tst_brk TBROK "unable to create a new keyring"
+
+ tst_is_num $keyring_id || \
+ tst_brk TBROK "unable to parse the new keyring id"
+
+ evmctl import $cert_file $keyring_id > /dev/null || \
+ tst_brk TBROK "unable to import a certificate into $keyring_name keyring"
+
+ grep $keyring_name $ASCII_MEASUREMENTS | tail -n1 | cut -d' ' -f6 | \
+ xxd -r -p > $temp_file
+
+ if [ ! -s $temp_file ]; then
+ tst_res TFAIL "keyring $keyring_name not found in $ASCII_MEASUREMENTS"
+ return
+ fi
+
+ if ! openssl x509 -in $temp_file -inform der > /dev/null; then
+ tst_res TFAIL "logged certificate is not a valid x509 certificate"
+ return
+ fi
+
+ if cmp -s $temp_file $cert_file; then
+ tst_res TPASS "logged certificate matches the original"
+ else
+ tst_res TFAIL "logged certificate does not match original"
+ fi
+}
+
tst_run
--
2.28.0