[bpf-next v2 05/10] selftests/bpf: Allow passing more information to BPF prog test run

[Krzesimir Nowak <krzesimir@kinvolk.io>]

The test case can specify a custom length of the data member, context
data and its length, which will be passed to
bpf_prog_test_run_xattr. For backward compatilibity, if the data
length is 0 (which is what will happen when the field is left
unspecified in the designated initializer of a struct), then the
length passed to the bpf_prog_test_run_xattr is TEST_DATA_LEN.

Also for backward compatilibity, if context data length is 0, NULL is
passed as a context to bpf_prog_test_run_xattr. This is to avoid
breaking other tests, where context data being NULL and context data
length being 0 is handled differently from the case where context data
is not NULL and context data length is 0.

Custom lengths still can't be greater than hardcoded 64 bytes for data
and 192 for context data.

192 for context data was picked to allow passing struct
bpf_perf_event_data as a context for perf event programs. The struct
is quite large, because it contains struct pt_regs.

Signed-off-by: Krzesimir Nowak <krzesimir@kinvolk.io>
---
 tools/testing/selftests/bpf/test_verifier.c | 68 +++++++++++++++++++--
 1 file changed, 62 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index db1f0f758f81..05bad54f481f 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -54,6 +54,7 @@
 #define MAX_TEST_RUNS	8
 #define POINTER_VALUE	0xcafe4all
 #define TEST_DATA_LEN	64
+#define TEST_CTX_LEN	192
 
 #define F_NEEDS_EFFICIENT_UNALIGNED_ACCESS	(1 << 0)
 #define F_LOAD_WITH_STRICT_ALIGNMENT		(1 << 1)
@@ -96,6 +97,9 @@ struct bpf_test {
 	enum bpf_prog_type prog_type;
 	uint8_t flags;
 	__u8 data[TEST_DATA_LEN];
+	__u32 data_len;
+	__u8 ctx[TEST_CTX_LEN];
+	__u32 ctx_len;
 	void (*fill_helper)(struct bpf_test *self);
 	uint8_t runs;
 	struct {
@@ -104,6 +108,9 @@ struct bpf_test {
 			__u8 data[TEST_DATA_LEN];
 			__u64 data64[TEST_DATA_LEN / 8];
 		};
+		__u32 data_len;
+		__u8 ctx[TEST_CTX_LEN];
+		__u32 ctx_len;
 	} retvals[MAX_TEST_RUNS];
 };
 
@@ -818,7 +825,7 @@ static int set_admin(bool admin)
 }
 
 static int do_prog_test_run(int fd_prog, bool unpriv, uint32_t expected_val,
-			    void *data, size_t size_data)
+			    void *data, size_t size_data, void *ctx, size_t size_ctx)
 {
 	__u8 tmp[TEST_DATA_LEN << 2];
 	__u32 size_tmp = sizeof(tmp);
@@ -831,6 +838,8 @@ static int do_prog_test_run(int fd_prog, bool unpriv, uint32_t expected_val,
 		.data_size_in = size_data,
 		.data_out = tmp,
 		.data_size_out = size_tmp,
+		.ctx_in = ctx,
+		.ctx_size_in = size_ctx,
 	};
 
 	if (unpriv)
@@ -956,13 +965,39 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
 	if (!alignment_prevented_execution && fd_prog >= 0) {
 		uint32_t expected_val;
 		int i;
+		__u32 size_data;
+		__u32 size_ctx;
+		bool bad_size;
+		void *ctx;
 
 		if (!test->runs) {
+			if (test->data_len > 0)
+				size_data = test->data_len;
+			else
+				size_data = sizeof(test->data);
+			size_ctx = test->ctx_len;
+			bad_size = false;
 			expected_val = unpriv && test->retval_unpriv ?
 				test->retval_unpriv : test->retval;
 
-			err = do_prog_test_run(fd_prog, unpriv, expected_val,
-					       test->data, sizeof(test->data));
+			if (size_data > sizeof(test->data)) {
+				printf("FAIL: data size (%u) greater than TEST_DATA_LEN (%lu) ", size_data, sizeof(test->data));
+				bad_size = true;
+			}
+			if (size_ctx > sizeof(test->ctx)) {
+				printf("FAIL: ctx size (%u) greater than TEST_CTX_LEN (%lu) ", size_ctx, sizeof(test->ctx));
+				bad_size = true;
+			}
+			if (size_ctx)
+				ctx = test->ctx;
+			else
+				ctx = NULL;
+			if (bad_size)
+				err = 1;
+			else
+				err = do_prog_test_run(fd_prog, unpriv, expected_val,
+						       test->data, size_data,
+						       ctx, size_ctx);
 			if (err)
 				run_errs++;
 			else
@@ -970,14 +1005,35 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
 		}
 
 		for (i = 0; i < test->runs; i++) {
+			if (test->retvals[i].data_len > 0)
+				size_data = test->retvals[i].data_len;
+			else
+				size_data = sizeof(test->retvals[i].data);
+			size_ctx = test->retvals[i].ctx_len;
+			bad_size = false;
 			if (unpriv && test->retvals[i].retval_unpriv)
 				expected_val = test->retvals[i].retval_unpriv;
 			else
 				expected_val = test->retvals[i].retval;
 
-			err = do_prog_test_run(fd_prog, unpriv, expected_val,
-					       test->retvals[i].data,
-					       sizeof(test->retvals[i].data));
+			if (size_data > sizeof(test->retvals[i].data)) {
+				printf("FAIL: data size (%u) at run %i greater than TEST_DATA_LEN (%lu) ", size_data, i + 1, sizeof(test->retvals[i].data));
+				bad_size = true;
+			}
+			if (size_ctx > sizeof(test->retvals[i].ctx)) {
+				printf("FAIL: ctx size (%u) at run %i greater than TEST_CTX_LEN (%lu) ", size_ctx, i + 1, sizeof(test->retvals[i].ctx));
+				bad_size = true;
+			}
+			if (size_ctx)
+				ctx = test->retvals[i].ctx;
+			else
+				ctx = NULL;
+			if (bad_size)
+				err = 1;
+			else
+				err = do_prog_test_run(fd_prog, unpriv, expected_val,
+						       test->retvals[i].data, size_data,
+						       ctx, size_ctx);
 			if (err) {
 				printf("(run %d/%d) ", i + 1, test->runs);
 				run_errs++;
-- 
2.20.1