From: Chiara Meiohas <cmeiohas@nvidia.com>

The first test validates that the BPF verifier accepts a program
that accesses the hook parameters (in_len) and returns
values in the valid errno range.

The second test validates that the BPF verifier rejects a program
that returns a positive value, which is outside the valid [-4095, 0]
return range for BPF-LSM hooks.

Signed-off-by: Chiara Meiohas <cmeiohas@nvidia.com>
Reviewed-by: Maher Sanalla <msanalla@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 tools/testing/selftests/bpf/progs/verifier_lsm.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/tools/testing/selftests/bpf/progs/verifier_lsm.c b/tools/testing/selftests/bpf/progs/verifier_lsm.c
index 38e8e91768620..9b2487948f8cb 100644
--- a/tools/testing/selftests/bpf/progs/verifier_lsm.c
+++ b/tools/testing/selftests/bpf/progs/verifier_lsm.c
@@ -188,4 +188,27 @@ int BPF_PROG(null_check, struct file *file)
 	return 0;
 }
 
+SEC("lsm/fw_validate_cmd")
+__description("lsm fw_validate_cmd: validate hook parameters")
+__success
+int BPF_PROG(fw_validate_cmd_test, const void *in, size_t in_len,
+	     const struct device *dev, enum fw_cmd_class class_id, u32 id)
+{
+	if (!in_len)
+		return -22;
+
+	return 0;
+}
+
+SEC("lsm/fw_validate_cmd")
+__description("lsm fw_validate_cmd: invalid positive return")
+__failure __msg("R0 has smin=1 smax=1 should have been in [-4095, 0]")
+__naked int fw_validate_cmd_fail(void *ctx)
+{
+	asm volatile (
+	"r0 = 1;"
+	"exit;"
+	::: __clobber_all);
+}
+
 char _license[] SEC("license") = "GPL";
-- 
2.53.0