selftests/bpf: add selftests for new insn_array map

Add the following selftests for new insn_array map:

* Incorrect instruction indexes are rejected
* Two programs can't use the same map
* BPF progs can't operate the map
* no changes to code => map is the same
* expected changes when instructions are added
* expected changes when instructions are deleted
* expected changes when multiple functions are present

Signed-off-by: Anton Protopopov <[e-mail]>
Acked-by: Eduard Zingerman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Alexei Starovoitov <[e-mail]>

tools/testing/selftests/bpf/prog_tests/bpf_insn_array.c

···
+// SPDX-License-Identifier: GPL-2.0
+
+#include <bpf/bpf.h>
+#include <test_progs.h>
+
+#ifdef __x86_64__
+static int map_create(__u32 map_type, __u32 max_entries)
+{
+	const char *map_name = "insn_array";
+	__u32 key_size = 4;
+	__u32 value_size = sizeof(struct bpf_insn_array_value);
+
+	return bpf_map_create(map_type, map_name, key_size, value_size, max_entries, NULL);
+}
+
+static int prog_load(struct bpf_insn *insns, __u32 insn_cnt, int *fd_array, __u32 fd_array_cnt)
+{
+	LIBBPF_OPTS(bpf_prog_load_opts, opts);
+
+	opts.fd_array = fd_array;
+	opts.fd_array_cnt = fd_array_cnt;
+
+	return bpf_prog_load(BPF_PROG_TYPE_XDP, NULL, "GPL", insns, insn_cnt, &opts);
+}
+
+static void __check_success(struct bpf_insn *insns, __u32 insn_cnt, __u32 *map_in, __u32 *map_out)
+{
+	struct bpf_insn_array_value val = {};
+	int prog_fd = -1, map_fd, i;
+
+	map_fd = map_create(BPF_MAP_TYPE_INSN_ARRAY, insn_cnt);
+	if (!ASSERT_GE(map_fd, 0, "map_create"))
+		return;
+
+	for (i = 0; i < insn_cnt; i++) {
+		val.orig_off = map_in[i];
+		if (!ASSERT_EQ(bpf_map_update_elem(map_fd, &i, &val, 0), 0, "bpf_map_update_elem"))
+			goto cleanup;
+	}
+
+	if (!ASSERT_EQ(bpf_map_freeze(map_fd), 0, "bpf_map_freeze"))
+		goto cleanup;
+
+	prog_fd = prog_load(insns, insn_cnt, &map_fd, 1);
+	if (!ASSERT_GE(prog_fd, 0, "bpf(BPF_PROG_LOAD)"))
+		goto cleanup;
+
+	for (i = 0; i < insn_cnt; i++) {
+		char buf[64];
+
+		if (!ASSERT_EQ(bpf_map_lookup_elem(map_fd, &i, &val), 0, "bpf_map_lookup_elem"))
+			goto cleanup;
+
+		snprintf(buf, sizeof(buf), "val.xlated_off should be equal map_out[%d]", i);
+		ASSERT_EQ(val.xlated_off, map_out[i], buf);
+	}
+
+cleanup:
+	close(prog_fd);
+	close(map_fd);
+}
+
+/*
+ * Load a program, which will not be anyhow mangled by the verifier.  Add an
+ * insn_array map pointing to every instruction. Check that it hasn't changed
+ * after the program load.
+ */
+static void check_one_to_one_mapping(void)
+{
+	struct bpf_insn insns[] = {
+		BPF_MOV64_IMM(BPF_REG_0, 4),
+		BPF_MOV64_IMM(BPF_REG_0, 3),
+		BPF_MOV64_IMM(BPF_REG_0, 2),
+		BPF_MOV64_IMM(BPF_REG_0, 1),
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	__u32 map_in[] = {0, 1, 2, 3, 4, 5};
+	__u32 map_out[] = {0, 1, 2, 3, 4, 5};
+
+	__check_success(insns, ARRAY_SIZE(insns), map_in, map_out);
+}
+
+/*
+ * Load a program with two patches (get jiffies, for simplicity). Add an
+ * insn_array map pointing to every instruction. Check how it was changed
+ * after the program load.
+ */
+static void check_simple(void)
+{
+	struct bpf_insn insns[] = {
+		BPF_MOV64_IMM(BPF_REG_0, 2),
+		BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_jiffies64),
+		BPF_MOV64_IMM(BPF_REG_0, 1),
+		BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_jiffies64),
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	__u32 map_in[] = {0, 1, 2, 3, 4, 5};
+	__u32 map_out[] = {0, 1, 4, 5, 8, 9};
+
+	__check_success(insns, ARRAY_SIZE(insns), map_in, map_out);
+}
+
+/*
+ * Verifier can delete code in two cases: nops & dead code. From insn
+ * array's point of view, the two cases are the same, so test using
+ * the simplest method: by loading some nops
+ */
+static void check_deletions(void)
+{
+	struct bpf_insn insns[] = {
+		BPF_MOV64_IMM(BPF_REG_0, 2),
+		BPF_JMP_IMM(BPF_JA, 0, 0, 0), /* nop */
+		BPF_MOV64_IMM(BPF_REG_0, 1),
+		BPF_JMP_IMM(BPF_JA, 0, 0, 0), /* nop */
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	__u32 map_in[] = {0, 1, 2, 3, 4, 5};
+	__u32 map_out[] = {0, -1, 1, -1, 2, 3};
+
+	__check_success(insns, ARRAY_SIZE(insns), map_in, map_out);
+}
+
+/*
+ * Same test as check_deletions, but also add code which adds instructions
+ */
+static void check_deletions_with_functions(void)
+{
+	struct bpf_insn insns[] = {
+		BPF_JMP_IMM(BPF_JA, 0, 0, 0), /* nop */
+		BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_jiffies64),
+		BPF_JMP_IMM(BPF_JA, 0, 0, 0), /* nop */
+		BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 2),
+		BPF_MOV64_IMM(BPF_REG_0, 1),
+		BPF_EXIT_INSN(),
+		BPF_JMP_IMM(BPF_JA, 0, 0, 0), /* nop */
+		BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_jiffies64),
+		BPF_JMP_IMM(BPF_JA, 0, 0, 0), /* nop */
+		BPF_MOV64_IMM(BPF_REG_0, 2),
+		BPF_EXIT_INSN(),
+	};
+	__u32 map_in[] =  { 0, 1,  2, 3, 4, 5, /* func */  6, 7,  8, 9, 10};
+	__u32 map_out[] = {-1, 0, -1, 3, 4, 5, /* func */ -1, 6, -1, 9, 10};
+
+	__check_success(insns, ARRAY_SIZE(insns), map_in, map_out);
+}
+
+/*
+ * Try to load a program with a map which points to outside of the program
+ */
+static void check_out_of_bounds_index(void)
+{
+	struct bpf_insn insns[] = {
+		BPF_MOV64_IMM(BPF_REG_0, 4),
+		BPF_MOV64_IMM(BPF_REG_0, 3),
+		BPF_MOV64_IMM(BPF_REG_0, 2),
+		BPF_MOV64_IMM(BPF_REG_0, 1),
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	int prog_fd, map_fd;
+	struct bpf_insn_array_value val = {};
+	int key;
+
+	map_fd = map_create(BPF_MAP_TYPE_INSN_ARRAY, 1);
+	if (!ASSERT_GE(map_fd, 0, "map_create"))
+		return;
+
+	key = 0;
+	val.orig_off = ARRAY_SIZE(insns); /* too big */
+	if (!ASSERT_EQ(bpf_map_update_elem(map_fd, &key, &val, 0), 0, "bpf_map_update_elem"))
+		goto cleanup;
+
+	if (!ASSERT_EQ(bpf_map_freeze(map_fd), 0, "bpf_map_freeze"))
+		goto cleanup;
+
+	prog_fd = prog_load(insns, ARRAY_SIZE(insns), &map_fd, 1);
+	if (!ASSERT_EQ(prog_fd, -EINVAL, "program should have been rejected (prog_fd != -EINVAL)")) {
+		close(prog_fd);
+		goto cleanup;
+	}
+
+cleanup:
+	close(map_fd);
+}
+
+/*
+ * Try to load a program with a map which points to the middle of 16-bit insn
+ */
+static void check_mid_insn_index(void)
+{
+	struct bpf_insn insns[] = {
+		BPF_LD_IMM64(BPF_REG_0, 0), /* 2 x 8 */
+		BPF_EXIT_INSN(),
+	};
+	int prog_fd, map_fd;
+	struct bpf_insn_array_value val = {};
+	int key;
+
+	map_fd = map_create(BPF_MAP_TYPE_INSN_ARRAY, 1);
+	if (!ASSERT_GE(map_fd, 0, "map_create"))
+		return;
+
+	key = 0;
+	val.orig_off = 1; /* middle of 16-byte instruction */
+	if (!ASSERT_EQ(bpf_map_update_elem(map_fd, &key, &val, 0), 0, "bpf_map_update_elem"))
+		goto cleanup;
+
+	if (!ASSERT_EQ(bpf_map_freeze(map_fd), 0, "bpf_map_freeze"))
+		goto cleanup;
+
+	prog_fd = prog_load(insns, ARRAY_SIZE(insns), &map_fd, 1);
+	if (!ASSERT_EQ(prog_fd, -EINVAL, "program should have been rejected (prog_fd != -EINVAL)")) {
+		close(prog_fd);
+		goto cleanup;
+	}
+
+cleanup:
+	close(map_fd);
+}
+
+static void check_incorrect_index(void)
+{
+	check_out_of_bounds_index();
+	check_mid_insn_index();
+}
+
+/* Once map was initialized, it should be frozen */
+static void check_load_unfrozen_map(void)
+{
+	struct bpf_insn insns[] = {
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	int prog_fd = -1, map_fd;
+	struct bpf_insn_array_value val = {};
+	int i;
+
+	map_fd = map_create(BPF_MAP_TYPE_INSN_ARRAY, ARRAY_SIZE(insns));
+	if (!ASSERT_GE(map_fd, 0, "map_create"))
+		return;
+
+	for (i = 0; i < ARRAY_SIZE(insns); i++) {
+		val.orig_off = i;
+		if (!ASSERT_EQ(bpf_map_update_elem(map_fd, &i, &val, 0), 0, "bpf_map_update_elem"))
+			goto cleanup;
+	}
+
+	prog_fd = prog_load(insns, ARRAY_SIZE(insns), &map_fd, 1);
+	if (!ASSERT_EQ(prog_fd, -EINVAL, "program should have been rejected (prog_fd != -EINVAL)"))
+		goto cleanup;
+
+	/* correctness: now freeze the map, the program should load fine */
+
+	if (!ASSERT_EQ(bpf_map_freeze(map_fd), 0, "bpf_map_freeze"))
+		goto cleanup;
+
+	prog_fd = prog_load(insns, ARRAY_SIZE(insns), &map_fd, 1);
+	if (!ASSERT_GE(prog_fd, 0, "bpf(BPF_PROG_LOAD)"))
+		goto cleanup;
+
+	for (i = 0; i < ARRAY_SIZE(insns); i++) {
+		if (!ASSERT_EQ(bpf_map_lookup_elem(map_fd, &i, &val), 0, "bpf_map_lookup_elem"))
+			goto cleanup;
+
+		ASSERT_EQ(val.xlated_off, i, "val should be equal i");
+	}
+
+cleanup:
+	close(prog_fd);
+	close(map_fd);
+}
+
+/* Map can be used only by one BPF program */
+static void check_no_map_reuse(void)
+{
+	struct bpf_insn insns[] = {
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	int prog_fd = -1, map_fd, extra_fd = -1;
+	struct bpf_insn_array_value val = {};
+	int i;
+
+	map_fd = map_create(BPF_MAP_TYPE_INSN_ARRAY, ARRAY_SIZE(insns));
+	if (!ASSERT_GE(map_fd, 0, "map_create"))
+		return;
+
+	for (i = 0; i < ARRAY_SIZE(insns); i++) {
+		val.orig_off = i;
+		if (!ASSERT_EQ(bpf_map_update_elem(map_fd, &i, &val, 0), 0, "bpf_map_update_elem"))
+			goto cleanup;
+	}
+
+	if (!ASSERT_EQ(bpf_map_freeze(map_fd), 0, "bpf_map_freeze"))
+		goto cleanup;
+
+	prog_fd = prog_load(insns, ARRAY_SIZE(insns), &map_fd, 1);
+	if (!ASSERT_GE(prog_fd, 0, "bpf(BPF_PROG_LOAD)"))
+		goto cleanup;
+
+	for (i = 0; i < ARRAY_SIZE(insns); i++) {
+		if (!ASSERT_EQ(bpf_map_lookup_elem(map_fd, &i, &val), 0, "bpf_map_lookup_elem"))
+			goto cleanup;
+
+		ASSERT_EQ(val.xlated_off, i, "val should be equal i");
+	}
+
+	extra_fd = prog_load(insns, ARRAY_SIZE(insns), &map_fd, 1);
+	if (!ASSERT_EQ(extra_fd, -EBUSY, "program should have been rejected (extra_fd != -EBUSY)"))
+		goto cleanup;
+
+	/* correctness: check that prog is still loadable without fd_array */
+	extra_fd = prog_load(insns, ARRAY_SIZE(insns), NULL, 0);
+	if (!ASSERT_GE(extra_fd, 0, "bpf(BPF_PROG_LOAD): expected no error"))
+		goto cleanup;
+
+cleanup:
+	close(extra_fd);
+	close(prog_fd);
+	close(map_fd);
+}
+
+static void check_bpf_no_lookup(void)
+{
+	struct bpf_insn insns[] = {
+		BPF_LD_MAP_FD(BPF_REG_1, 0),
+		BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+		BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+		BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+		BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+		BPF_EXIT_INSN(),
+	};
+	int prog_fd = -1, map_fd;
+
+	map_fd = map_create(BPF_MAP_TYPE_INSN_ARRAY, 1);
+	if (!ASSERT_GE(map_fd, 0, "map_create"))
+		return;
+
+	insns[0].imm = map_fd;
+
+	if (!ASSERT_EQ(bpf_map_freeze(map_fd), 0, "bpf_map_freeze"))
+		goto cleanup;
+
+	prog_fd = prog_load(insns, ARRAY_SIZE(insns), NULL, 0);
+	if (!ASSERT_EQ(prog_fd, -EINVAL, "program should have been rejected (prog_fd != -EINVAL)"))
+		goto cleanup;
+
+	/* correctness: check that prog is still loadable with normal map */
+	close(map_fd);
+	map_fd = map_create(BPF_MAP_TYPE_ARRAY, 1);
+	insns[0].imm = map_fd;
+	prog_fd = prog_load(insns, ARRAY_SIZE(insns), NULL, 0);
+	if (!ASSERT_GE(prog_fd, 0, "bpf(BPF_PROG_LOAD)"))
+		goto cleanup;
+
+cleanup:
+	close(prog_fd);
+	close(map_fd);
+}
+
+static void check_bpf_side(void)
+{
+	check_bpf_no_lookup();
+}
+
+static void __test_bpf_insn_array(void)
+{
+	/* Test if offsets are adjusted properly */
+
+	if (test__start_subtest("one2one"))
+		check_one_to_one_mapping();
+
+	if (test__start_subtest("simple"))
+		check_simple();
+
+	if (test__start_subtest("deletions"))
+		check_deletions();
+
+	if (test__start_subtest("deletions-with-functions"))
+		check_deletions_with_functions();
+
+	/* Check all kinds of operations and related restrictions */
+
+	if (test__start_subtest("incorrect-index"))
+		check_incorrect_index();
+
+	if (test__start_subtest("load-unfrozen-map"))
+		check_load_unfrozen_map();
+
+	if (test__start_subtest("no-map-reuse"))
+		check_no_map_reuse();
+
+	if (test__start_subtest("bpf-side-ops"))
+		check_bpf_side();
+}
+#else
+static void __test_bpf_insn_array(void)
+{
+	test__skip();
+}
+#endif
+
+void test_bpf_insn_array(void)
+{
+	__test_bpf_insn_array();
+}