[PATCH ima-evm-utils v2 2/2] Add test for using sign_hash API

Patrick Uiterwijk
2021-07-05T15:58:23Z

This adds a test with a small program that calls the sign_hash API, to
ensure that that codepath works.

Signed-off-by: Patrick Uiterwijk <patrick@puiterwijk.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
---
src/evmctl.c | 23 ----------------
src/utils.c | 20 ++++++++++++++
src/utils.h | 1 +
tests/.gitignore | 2 ++
tests/Makefile.am | 5 ++++
tests/sign_verify.apitest.c | 55 +++++++++++++++++++++++++++++++++++++
tests/sign_verify.test | 30 ++++++++++++++++----
7 files changed, 107 insertions(+), 29 deletions(-)
create mode 100644 tests/sign_verify.apitest.c

diff --git a/src/evmctl.c b/src/evmctl.c
index 7a6f202..867b142 100644
--- a/src/evmctl.c
+++ b/src/evmctl.c
@@ -166,29 +166,6 @@ struct tpm_bank_info {
static char *pcrfile[MAX_PCRFILE];
static unsigned npcrfile;

-static int bin2file(const char *file, const char *ext, const unsigned char *data, int len)
-{
- FILE *fp;
- char name[strlen(file) + (ext ? strlen(ext) : 0) + 2];
- int err;
-
- if (ext)
- sprintf(name, "%s.%s", file, ext);
- else
- sprintf(name, "%s", file);
-
- log_info("Writing to %s\n", name);
-
- fp = fopen(name, "w");
- if (!fp) {
- log_err("Failed to open: %s\n", name);
- return -1;
- }
- err = fwrite(data, len, 1, fp);
- fclose(fp);
- return err;
-}
-
static unsigned char *file2bin(const char *file, const char *ext, int *size)
{
FILE *fp;
diff --git a/src/utils.c b/src/utils.c
index fbb6a4b..ce2cc28 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -112,3 +112,23 @@ int hex2bin(void *dst, const char *src, size_t count)
}
return 0;
}
+
+int bin2file(const char *file, const char *ext, const unsigned char *data, int len)
+{
+ FILE *fp;
+ char name[strlen(file) + (ext ? strlen(ext) : 0) + 2];
+ int err;
+
+ if (ext)
+ sprintf(name, "%s.%s", file, ext);
+ else
+ sprintf(name, "%s", file);
+
+ fp = fopen(name, "w");
+ if (!fp)
+ return -1;
+
+ err = fwrite(data, len, 1, fp);
+ fclose(fp);
+ return err;
+}
diff --git a/src/utils.h b/src/utils.h
index 9ea179f..081997a 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -4,3 +4,4 @@
int get_cmd_path(const char *prog_name, char *buf, size_t buf_len);
int hex_to_bin(char ch);
int hex2bin(void *dst, const char *src, size_t count);
+int bin2file(const char *file, const char *ext, const unsigned char *data, int len);
diff --git a/tests/.gitignore b/tests/.gitignore
index 9ecc984..c40735d 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -14,3 +14,5 @@
*.key
*.conf

+# Compiled version of apitest
+sign_verify_apitest
diff --git a/tests/Makefile.am b/tests/Makefile.am
index ff928e1..74f6125 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -10,3 +10,8 @@ distclean: distclean-keys
.PHONY: distclean-keys
distclean-keys:
./gen-keys.sh clean
+
+AUTOMAKE_OPTIONS = subdir-objects
+bin_PROGRAMS = sign_verify_apitest
+sign_verify_apitest_SOURCES = sign_verify.apitest.c ../src/utils.c
+sign_verify_apitest_LDFLAGS = -limaevm -L../src/.libs
diff --git a/tests/sign_verify.apitest.c b/tests/sign_verify.apitest.c
new file mode 100644
index 0000000..3fcd043
--- /dev/null
+++ b/tests/sign_verify.apitest.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * sign_verify.apitest: Test program for verifying sign_hash
+ *
+ * Copyright (C) 2021 Patrick Uiterwijk <patrick@puiterwijk.org>
+ * Copyright (C) 2013,2014 Samsung Electronics
+ * Copyright (C) 2011,2012,2013 Intel Corporation
+ * Copyright (C) 2011 Nokia Corporation
+ */
+
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/xattr.h>
+
+#include "../src/imaevm.h"
+#include "../src/utils.h"
+
+int main(int argc, char **argv)
+{
+ unsigned char hash[MAX_DIGEST_SIZE];
+ unsigned char sig[MAX_SIGNATURE_SIZE];
+ int len, err;
+ char *file = argv[1];
+ char *key = argv[2];
+ char *algo = argv[3];
+ char *digest = argv[4];
+
+ len = strlen(digest) / 2;
+ if (hex2bin(hash, digest, len) != 0) {
+ fprintf(stderr, "Error during hex2bin\n");
+ return 1;
+ }
+
+ len = sign_hash(algo, hash, len, key, NULL, sig + 1);
+ if (len <= 1) {
+ fprintf(stderr, "Error signing\n");
+ return 1;
+ }
+
+ /* add header */
+ len++;
+ sig[0] = EVM_IMA_XATTR_DIGSIG;
+
+ bin2file(file, "sig", sig, len);
+
+ err = lsetxattr(file, "user.ima", sig, len, 0);
+ if (err < 0) {
+ log_err("setxattr failed: %s\n", file);
+ return 1;
+ }
+
+ return 0;
+}
diff --git a/tests/sign_verify.test b/tests/sign_verify.test
index 3d7aa51..6f92801 100755
--- a/tests/sign_verify.test
+++ b/tests/sign_verify.test
@@ -66,14 +66,14 @@ _keyid_from_cert() {

# Convert test $type into evmctl op prefix
_op() {
- if [ "$1" = ima ]; then
+ if [ "$1" = ima -o "$1" = ima_api ]; then
echo ima_
fi
}

# Convert test $type into xattr name
_xattr() {
- if [ "$1" = ima ]; then
+ if [ "$1" = ima -o "$1" = ima_api ]; then
echo user.ima
else
echo user.evm
@@ -113,11 +113,13 @@ _evmctl_sign() {
[ "$type" = ima ] && opts+=" --sigfile"

# shellcheck disable=SC2086
- ADD_TEXT_FOR="$alg ($key)" ADD_DEL=$file \
+ [ "$type" = ima -o "$type" = evm ] && (ADD_TEXT_FOR="$alg ($key)" ADD_DEL=$file \
_evmctl_run "$(_op "$type")sign" $opts \
- --hashalgo "$alg" --key "$key" --xattr-user "$file" || return
+ --hashalgo "$alg" --key "$key" --xattr-user "$file" || return)
+ [ "$type" = ima_api ] && ADD_TEXT_FOR="$alg ($key)" ADD_DEL=$file \
+ ./sign_verify_apitest "$file" "$key" "$alg" "$(openssl dgst $OPENSSL_ENGINE -$ALG -hex -r $FILE | awk '{print $1}')"

- if [ "$type" = ima ]; then
+ if [ "$type" = ima -o "$type" = ima_api ]; then
_test_sigfile "$file" "$(_xattr "$type")" "$file.sig" "$file.sig2"
fi
}
@@ -125,12 +127,14 @@ _evmctl_sign() {
# Run and test {ima_,}sign operation
check_sign() {
# Arguments are passed via global vars:
- # TYPE (ima or evm),
+ # TYPE (ima, ima_api or evm),
# KEY,
# ALG (hash algo),
# PREFIX (signature header prefix in hex),
# OPTS (additional options for evmctl),
# FILE (working file to sign).
+ [ "$TYPE" = ima_api ] && [[ "$OPTS" =~ --rsa ]] && return "$SKIP"
+
local "$@"
local KEY=${KEY%.*}.key
local FILE=${FILE:-$ALG.txt}
@@ -268,6 +272,20 @@ sign_verify() {
# Multiple files and some don't verify
expect_fail check_verify FILE="/dev/null $file"

+ setfattr -x user.ima "$FILE"
+ rm "$FILE.sig"
+ fi
+
+ TYPE=ima_api
+ if expect_pass check_sign; then
+
+ # Normal verify with proper key should pass
+ expect_pass check_verify
+ expect_pass check_verify OPTS="--sigfile"
+
+ # Multiple files and some don't verify
+ expect_fail check_verify FILE="/dev/null $file"
+
rm "$FILE.sig"
fi

--
2.31.1