From: Shuah Khan [mailto:skhan@linuxfoundation.org] Sent: Tuesday, February 15, 2022 5:11 PM On 2/15/22 5:40 AM, Roberto Sassu wrote:
Test the ability of bpf_lsm_kernel_read_file() to call the sleepable functions bpf_ima_inode_hash() or bpf_ima_file_hash() to obtain a measurement of a loaded IMA policy.
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com
tools/testing/selftests/bpf/ima_setup.sh | 2 ++ .../selftests/bpf/prog_tests/test_ima.c | 3 +- tools/testing/selftests/bpf/progs/ima.c | 28 ++++++++++++++++--- 3 files changed, 28 insertions(+), 5 deletions(-)
diff --git a/tools/testing/selftests/bpf/ima_setup.sh
b/tools/testing/selftests/bpf/ima_setup.sh
index 8e62581113a3..82530f19f85a 100755 --- a/tools/testing/selftests/bpf/ima_setup.sh +++ b/tools/testing/selftests/bpf/ima_setup.sh @@ -51,6 +51,7 @@ setup()
ensure_mount_securityfs echo "measure func=BPRM_CHECK fsuuid=${mount_uuid}" >
${IMA_POLICY_FILE}
- echo "measure func=BPRM_CHECK fsuuid=${mount_uuid}" >
${mount_dir}/policy_test
}
cleanup() { @@ -74,6 +75,7 @@ run() local mount_dir="${tmp_dir}/mnt" local copied_bin_path="${mount_dir}/$(basename ${TEST_BINARY})"
- echo ${mount_dir}/policy_test > ${IMA_POLICY_FILE} exec "${copied_bin_path}" }
diff --git a/tools/testing/selftests/bpf/prog_tests/test_ima.c
b/tools/testing/selftests/bpf/prog_tests/test_ima.c
index 62bf0e830453..c4a62d7b70df 100644 --- a/tools/testing/selftests/bpf/prog_tests/test_ima.c +++ b/tools/testing/selftests/bpf/prog_tests/test_ima.c @@ -97,8 +97,9 @@ void test_test_ima(void) /* * 1 sample with use_ima_file_hash = false * 2 samples with use_ima_file_hash = true (./ima_setup.sh, /bin/true)
* 1 sample with use_ima_file_hash = true (IMA policy)
- ASSERT_EQ(err, 3, "num_samples_or_err");
ASSERT_EQ(err, 4, "num_samples_or_err"); ASSERT_NEQ(ima_hash_from_bpf, 0, "ima_hash");
close_clean:
diff --git a/tools/testing/selftests/bpf/progs/ima.c
b/tools/testing/selftests/bpf/progs/ima.c
index 9bb63f96cfc0..9b4c03f30a1c 100644 --- a/tools/testing/selftests/bpf/progs/ima.c +++ b/tools/testing/selftests/bpf/progs/ima.c @@ -20,8 +20,7 @@ char _license[] SEC("license") = "GPL";
bool use_ima_file_hash;
-SEC("lsm.s/bprm_committed_creds") -void BPF_PROG(ima, struct linux_binprm *bprm) +static void ima_test_common(struct file *file) { u64 ima_hash = 0; u64 *sample; @@ -31,10 +30,10 @@ void BPF_PROG(ima, struct linux_binprm *bprm) pid = bpf_get_current_pid_tgid() >> 32; if (pid == monitored_pid) { if (!use_ima_file_hash)
ret = bpf_ima_inode_hash(bprm->file->f_inode,&ima_hash,
ret = bpf_ima_inode_hash(file->f_inode, &ima_hash, sizeof(ima_hash));
ret = bpf_ima_file_hash(bprm->file, &ima_hash,
ret = bpf_ima_file_hash(file, &ima_hash, sizeof(ima_hash));Is this considered an error? Does it make sense for this test to be void type and not return the error to its callers? One of the callers below seems to care for return values.
The user space side of the test (test_ima.c) seems to check the number of samples obtained from the ring buffer. A failure here would result in the sample not being sent to that component.
Another test, as you suggest, could be to ensure that the kernel_read_file hook is able to deny operations. I would check this in a separate test.
Thanks
Roberto
HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063 Managing Director: Li Peng, Zhong Ronghua
return;@@ -49,3 +48,24 @@ void BPF_PROG(ima, struct linux_binprm *bprm)
return; }
+SEC("lsm.s/bprm_committed_creds") +void BPF_PROG(ima, struct linux_binprm *bprm) +{
- ima_test_common(bprm->file);
+}
+SEC("lsm.s/kernel_read_file") +int BPF_PROG(kernel_read_file, struct file *file, enum kernel_read_file_id id,
bool contents)+{
- if (!contents)
return 0;- if (id != READING_POLICY)
return 0;- ima_test_common(file);
This one here.
- return 0;
+}
thanks, -- Shuah