[PATCH v3 5/9] selftests/bpf: Add test for bpf_ima_file_hash()

Roberto Sassu
2022-03-02T11:18:48Z

Add new test to ensure that bpf_ima_file_hash() returns the digest of the
executed files.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
.../selftests/bpf/prog_tests/test_ima.c | 43 +++++++++++++++++--
tools/testing/selftests/bpf/progs/ima.c | 10 ++++-
2 files changed, 47 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/test_ima.c b/tools/testing/selftests/bpf/prog_tests/test_ima.c
index 97d8a6f84f4a..acc911ba63fd 100644
--- a/tools/testing/selftests/bpf/prog_tests/test_ima.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_ima.c
@@ -13,6 +13,8 @@

#include "ima.skel.h"

+#define MAX_SAMPLES 2
+
static int run_measured_process(const char *measured_dir, u32 *monitored_pid)
{
int child_pid, child_status;
@@ -32,14 +34,25 @@ static int run_measured_process(const char *measured_dir, u32 *monitored_pid)
return -EINVAL;
}

-static u64 ima_hash_from_bpf;
+static u64 ima_hash_from_bpf[MAX_SAMPLES];
+static int ima_hash_from_bpf_idx;

static int process_sample(void *ctx, void *data, size_t len)
{
- ima_hash_from_bpf = *((u64 *)data);
+ if (ima_hash_from_bpf_idx >= MAX_SAMPLES)
+ return -ENOSPC;
+
+ ima_hash_from_bpf[ima_hash_from_bpf_idx++] = *((u64 *)data);
return 0;
}

+static void test_init(struct ima__bss *bss)
+{
+ ima_hash_from_bpf_idx = 0;
+
+ bss->use_ima_file_hash = false;
+}
+
void test_test_ima(void)
{
char measured_dir_template[] = "/tmp/ima_measuredXXXXXX";
@@ -72,13 +85,35 @@ void test_test_ima(void)
if (CHECK(err, "failed to run command", "%s, errno = %d\n", cmd, errno))
goto close_clean;

+ /*
+ * Test #1
+ * - Goal: obtain a sample with the bpf_ima_inode_hash() helper
+ * - Expected result: 1 sample (/bin/true)
+ */
+ test_init(skel->bss);
err = run_measured_process(measured_dir, &skel->bss->monitored_pid);
- if (CHECK(err, "run_measured_process", "err = %d\n", err))
+ if (CHECK(err, "run_measured_process #1", "err = %d\n", err))
goto close_clean;

err = ring_buffer__consume(ringbuf);
ASSERT_EQ(err, 1, "num_samples_or_err");
- ASSERT_NEQ(ima_hash_from_bpf, 0, "ima_hash");
+ ASSERT_NEQ(ima_hash_from_bpf[0], 0, "ima_hash");
+
+ /*
+ * Test #2
+ * - Goal: obtain samples with the bpf_ima_file_hash() helper
+ * - Expected result: 2 samples (./ima_setup.sh, /bin/true)
+ */
+ test_init(skel->bss);
+ skel->bss->use_ima_file_hash = true;
+ err = run_measured_process(measured_dir, &skel->bss->monitored_pid);
+ if (CHECK(err, "run_measured_process #2", "err = %d\n", err))
+ goto close_clean;
+
+ err = ring_buffer__consume(ringbuf);
+ ASSERT_EQ(err, 2, "num_samples_or_err");
+ ASSERT_NEQ(ima_hash_from_bpf[0], 0, "ima_hash");
+ ASSERT_NEQ(ima_hash_from_bpf[1], 0, "ima_hash");

close_clean:
snprintf(cmd, sizeof(cmd), "./ima_setup.sh cleanup %s", measured_dir);
diff --git a/tools/testing/selftests/bpf/progs/ima.c b/tools/testing/selftests/bpf/progs/ima.c
index b5a0de50d1b4..e0b073dcfb5d 100644
--- a/tools/testing/selftests/bpf/progs/ima.c
+++ b/tools/testing/selftests/bpf/progs/ima.c
@@ -18,6 +18,8 @@ struct {

char _license[] SEC("license") = "GPL";

+bool use_ima_file_hash;
+
static void ima_test_common(struct file *file)
{
u64 ima_hash = 0;
@@ -27,8 +29,12 @@ static void ima_test_common(struct file *file)

pid = bpf_get_current_pid_tgid() >> 32;
if (pid == monitored_pid) {
- ret = bpf_ima_inode_hash(file->f_inode, &ima_hash,
- sizeof(ima_hash));
+ if (!use_ima_file_hash)
+ ret = bpf_ima_inode_hash(file->f_inode, &ima_hash,
+ sizeof(ima_hash));
+ else
+ ret = bpf_ima_file_hash(file, &ima_hash,
+ sizeof(ima_hash));
if (ret < 0 || ima_hash == 0)
return;

--
2.32.0