selftests/bpf: Add BTF sanity tests

Preparing the metadata for bpf_list_head involves a complicated parsing
step and type resolution for the contained value. Ensure that corner
cases are tested against and invalid specifications in source are duly
rejected. Also include tests for incorrect ownership relationships in
the BTF.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20221118015614.2013203-24-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 485 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/linked_list.c b/tools/testing/selftests/bpf/prog_tests/linked_list.c
index 41e588807321..dd73d0a62c6e 100644
--- a/tools/testing/selftests/bpf/prog_tests/linked_list.c
+++ b/tools/testing/selftests/bpf/prog_tests/linked_list.c
@@ -1,4 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
+#include <bpf/btf.h>
+#include <test_btf.h>
+#include <linux/btf.h>
 #include <test_progs.h>
 #include <network_helpers.h>
 
@@ -235,6 +238,487 @@ end:
 	linked_list__destroy(skel);
 }
 
+#define SPIN_LOCK 2
+#define LIST_HEAD 3
+#define LIST_NODE 4
+
+static struct btf *init_btf(void)
+{
+	int id, lid, hid, nid;
+	struct btf *btf;
+
+	btf = btf__new_empty();
+	if (!ASSERT_OK_PTR(btf, "btf__new_empty"))
+		return NULL;
+	id = btf__add_int(btf, "int", 4, BTF_INT_SIGNED);
+	if (!ASSERT_EQ(id, 1, "btf__add_int"))
+		goto end;
+	lid = btf__add_struct(btf, "bpf_spin_lock", 4);
+	if (!ASSERT_EQ(lid, SPIN_LOCK, "btf__add_struct bpf_spin_lock"))
+		goto end;
+	hid = btf__add_struct(btf, "bpf_list_head", 16);
+	if (!ASSERT_EQ(hid, LIST_HEAD, "btf__add_struct bpf_list_head"))
+		goto end;
+	nid = btf__add_struct(btf, "bpf_list_node", 16);
+	if (!ASSERT_EQ(nid, LIST_NODE, "btf__add_struct bpf_list_node"))
+		goto end;
+	return btf;
+end:
+	btf__free(btf);
+	return NULL;
+}
+
+static void test_btf(void)
+{
+	struct btf *btf = NULL;
+	int id, err;
+
+	while (test__start_subtest("btf: too many locks")) {
+		btf = init_btf();
+		if (!ASSERT_OK_PTR(btf, "init_btf"))
+			break;
+		id = btf__add_struct(btf, "foo", 24);
+		if (!ASSERT_EQ(id, 5, "btf__add_struct foo"))
+			break;
+		err = btf__add_field(btf, "a", SPIN_LOCK, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_struct foo::a"))
+			break;
+		err = btf__add_field(btf, "b", SPIN_LOCK, 32, 0);
+		if (!ASSERT_OK(err, "btf__add_struct foo::a"))
+			break;
+		err = btf__add_field(btf, "c", LIST_HEAD, 64, 0);
+		if (!ASSERT_OK(err, "btf__add_struct foo::a"))
+			break;
+
+		err = btf__load_into_kernel(btf);
+		ASSERT_EQ(err, -E2BIG, "check btf");
+		btf__free(btf);
+		break;
+	}
+
+	while (test__start_subtest("btf: missing lock")) {
+		btf = init_btf();
+		if (!ASSERT_OK_PTR(btf, "init_btf"))
+			break;
+		id = btf__add_struct(btf, "foo", 16);
+		if (!ASSERT_EQ(id, 5, "btf__add_struct foo"))
+			break;
+		err = btf__add_field(btf, "a", LIST_HEAD, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_struct foo::a"))
+			break;
+		id = btf__add_decl_tag(btf, "contains:baz:a", 5, 0);
+		if (!ASSERT_EQ(id, 6, "btf__add_decl_tag contains:baz:a"))
+			break;
+		id = btf__add_struct(btf, "baz", 16);
+		if (!ASSERT_EQ(id, 7, "btf__add_struct baz"))
+			break;
+		err = btf__add_field(btf, "a", LIST_NODE, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field baz::a"))
+			break;
+
+		err = btf__load_into_kernel(btf);
+		ASSERT_EQ(err, -EINVAL, "check btf");
+		btf__free(btf);
+		break;
+	}
+
+	while (test__start_subtest("btf: bad offset")) {
+		btf = init_btf();
+		if (!ASSERT_OK_PTR(btf, "init_btf"))
+			break;
+		id = btf__add_struct(btf, "foo", 36);
+		if (!ASSERT_EQ(id, 5, "btf__add_struct foo"))
+			break;
+		err = btf__add_field(btf, "a", LIST_HEAD, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::a"))
+			break;
+		err = btf__add_field(btf, "b", LIST_NODE, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::b"))
+			break;
+		err = btf__add_field(btf, "c", SPIN_LOCK, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::c"))
+			break;
+		id = btf__add_decl_tag(btf, "contains:foo:b", 5, 0);
+		if (!ASSERT_EQ(id, 6, "btf__add_decl_tag contains:foo:b"))
+			break;
+
+		err = btf__load_into_kernel(btf);
+		ASSERT_EQ(err, -EEXIST, "check btf");
+		btf__free(btf);
+		break;
+	}
+
+	while (test__start_subtest("btf: missing contains:")) {
+		btf = init_btf();
+		if (!ASSERT_OK_PTR(btf, "init_btf"))
+			break;
+		id = btf__add_struct(btf, "foo", 24);
+		if (!ASSERT_EQ(id, 5, "btf__add_struct foo"))
+			break;
+		err = btf__add_field(btf, "a", SPIN_LOCK, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::a"))
+			break;
+		err = btf__add_field(btf, "b", LIST_HEAD, 64, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::b"))
+			break;
+
+		err = btf__load_into_kernel(btf);
+		ASSERT_EQ(err, -EINVAL, "check btf");
+		btf__free(btf);
+		break;
+	}
+
+	while (test__start_subtest("btf: missing struct")) {
+		btf = init_btf();
+		if (!ASSERT_OK_PTR(btf, "init_btf"))
+			break;
+		id = btf__add_struct(btf, "foo", 24);
+		if (!ASSERT_EQ(id, 5, "btf__add_struct foo"))
+			break;
+		err = btf__add_field(btf, "a", SPIN_LOCK, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::a"))
+			break;
+		err = btf__add_field(btf, "b", LIST_HEAD, 64, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::b"))
+			break;
+		id = btf__add_decl_tag(btf, "contains:bar:bar", 5, 1);
+		if (!ASSERT_EQ(id, 6, "btf__add_decl_tag contains:bar:bar"))
+			break;
+
+		err = btf__load_into_kernel(btf);
+		ASSERT_EQ(err, -ENOENT, "check btf");
+		btf__free(btf);
+		break;
+	}
+
+	while (test__start_subtest("btf: missing node")) {
+		btf = init_btf();
+		if (!ASSERT_OK_PTR(btf, "init_btf"))
+			break;
+		id = btf__add_struct(btf, "foo", 24);
+		if (!ASSERT_EQ(id, 5, "btf__add_struct foo"))
+			break;
+		err = btf__add_field(btf, "a", SPIN_LOCK, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::a"))
+			break;
+		err = btf__add_field(btf, "b", LIST_HEAD, 64, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::b"))
+			break;
+		id = btf__add_decl_tag(btf, "contains:foo:c", 5, 1);
+		if (!ASSERT_EQ(id, 6, "btf__add_decl_tag contains:foo:c"))
+			break;
+
+		err = btf__load_into_kernel(btf);
+		btf__free(btf);
+		ASSERT_EQ(err, -ENOENT, "check btf");
+		break;
+	}
+
+	while (test__start_subtest("btf: node incorrect type")) {
+		btf = init_btf();
+		if (!ASSERT_OK_PTR(btf, "init_btf"))
+			break;
+		id = btf__add_struct(btf, "foo", 20);
+		if (!ASSERT_EQ(id, 5, "btf__add_struct foo"))
+			break;
+		err = btf__add_field(btf, "a", LIST_HEAD, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::a"))
+			break;
+		err = btf__add_field(btf, "b", SPIN_LOCK, 128, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::b"))
+			break;
+		id = btf__add_decl_tag(btf, "contains:bar:a", 5, 0);
+		if (!ASSERT_EQ(id, 6, "btf__add_decl_tag contains:bar:a"))
+			break;
+		id = btf__add_struct(btf, "bar", 4);
+		if (!ASSERT_EQ(id, 7, "btf__add_struct bar"))
+			break;
+		err = btf__add_field(btf, "a", SPIN_LOCK, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field bar::a"))
+			break;
+
+		err = btf__load_into_kernel(btf);
+		ASSERT_EQ(err, -EINVAL, "check btf");
+		btf__free(btf);
+		break;
+	}
+
+	while (test__start_subtest("btf: multiple bpf_list_node with name b")) {
+		btf = init_btf();
+		if (!ASSERT_OK_PTR(btf, "init_btf"))
+			break;
+		id = btf__add_struct(btf, "foo", 52);
+		if (!ASSERT_EQ(id, 5, "btf__add_struct foo"))
+			break;
+		err = btf__add_field(btf, "a", LIST_HEAD, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::a"))
+			break;
+		err = btf__add_field(btf, "b", LIST_NODE, 128, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::b"))
+			break;
+		err = btf__add_field(btf, "b", LIST_NODE, 256, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::c"))
+			break;
+		err = btf__add_field(btf, "d", SPIN_LOCK, 384, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::d"))
+			break;
+		id = btf__add_decl_tag(btf, "contains:foo:b", 5, 0);
+		if (!ASSERT_EQ(id, 6, "btf__add_decl_tag contains:foo:b"))
+			break;
+
+		err = btf__load_into_kernel(btf);
+		ASSERT_EQ(err, -EINVAL, "check btf");
+		btf__free(btf);
+		break;
+	}
+
+	while (test__start_subtest("btf: owning | owned AA cycle")) {
+		btf = init_btf();
+		if (!ASSERT_OK_PTR(btf, "init_btf"))
+			break;
+		id = btf__add_struct(btf, "foo", 36);
+		if (!ASSERT_EQ(id, 5, "btf__add_struct foo"))
+			break;
+		err = btf__add_field(btf, "a", LIST_HEAD, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::a"))
+			break;
+		err = btf__add_field(btf, "b", LIST_NODE, 128, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::b"))
+			break;
+		err = btf__add_field(btf, "c", SPIN_LOCK, 256, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::c"))
+			break;
+		id = btf__add_decl_tag(btf, "contains:foo:b", 5, 0);
+		if (!ASSERT_EQ(id, 6, "btf__add_decl_tag contains:foo:b"))
+			break;
+
+		err = btf__load_into_kernel(btf);
+		ASSERT_EQ(err, -ELOOP, "check btf");
+		btf__free(btf);
+		break;
+	}
+
+	while (test__start_subtest("btf: owning | owned ABA cycle")) {
+		btf = init_btf();
+		if (!ASSERT_OK_PTR(btf, "init_btf"))
+			break;
+		id = btf__add_struct(btf, "foo", 36);
+		if (!ASSERT_EQ(id, 5, "btf__add_struct foo"))
+			break;
+		err = btf__add_field(btf, "a", LIST_HEAD, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::a"))
+			break;
+		err = btf__add_field(btf, "b", LIST_NODE, 128, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::b"))
+			break;
+		err = btf__add_field(btf, "c", SPIN_LOCK, 256, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::c"))
+			break;
+		id = btf__add_decl_tag(btf, "contains:bar:b", 5, 0);
+		if (!ASSERT_EQ(id, 6, "btf__add_decl_tag contains:bar:b"))
+			break;
+		id = btf__add_struct(btf, "bar", 36);
+		if (!ASSERT_EQ(id, 7, "btf__add_struct bar"))
+			break;
+		err = btf__add_field(btf, "a", LIST_HEAD, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field bar::a"))
+			break;
+		err = btf__add_field(btf, "b", LIST_NODE, 128, 0);
+		if (!ASSERT_OK(err, "btf__add_field bar::b"))
+			break;
+		err = btf__add_field(btf, "c", SPIN_LOCK, 256, 0);
+		if (!ASSERT_OK(err, "btf__add_field bar::c"))
+			break;
+		id = btf__add_decl_tag(btf, "contains:foo:b", 7, 0);
+		if (!ASSERT_EQ(id, 8, "btf__add_decl_tag contains:foo:b"))
+			break;
+
+		err = btf__load_into_kernel(btf);
+		ASSERT_EQ(err, -ELOOP, "check btf");
+		btf__free(btf);
+		break;
+	}
+
+	while (test__start_subtest("btf: owning -> owned")) {
+		btf = init_btf();
+		if (!ASSERT_OK_PTR(btf, "init_btf"))
+			break;
+		id = btf__add_struct(btf, "foo", 20);
+		if (!ASSERT_EQ(id, 5, "btf__add_struct foo"))
+			break;
+		err = btf__add_field(btf, "a", LIST_HEAD, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::a"))
+			break;
+		err = btf__add_field(btf, "b", SPIN_LOCK, 128, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::b"))
+			break;
+		id = btf__add_decl_tag(btf, "contains:bar:a", 5, 0);
+		if (!ASSERT_EQ(id, 6, "btf__add_decl_tag contains:bar:a"))
+			break;
+		id = btf__add_struct(btf, "bar", 16);
+		if (!ASSERT_EQ(id, 7, "btf__add_struct bar"))
+			break;
+		err = btf__add_field(btf, "a", LIST_NODE, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field bar::a"))
+			break;
+
+		err = btf__load_into_kernel(btf);
+		ASSERT_EQ(err, 0, "check btf");
+		btf__free(btf);
+		break;
+	}
+
+	while (test__start_subtest("btf: owning -> owning | owned -> owned")) {
+		btf = init_btf();
+		if (!ASSERT_OK_PTR(btf, "init_btf"))
+			break;
+		id = btf__add_struct(btf, "foo", 20);
+		if (!ASSERT_EQ(id, 5, "btf__add_struct foo"))
+			break;
+		err = btf__add_field(btf, "a", LIST_HEAD, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::a"))
+			break;
+		err = btf__add_field(btf, "b", SPIN_LOCK, 128, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::b"))
+			break;
+		id = btf__add_decl_tag(btf, "contains:bar:b", 5, 0);
+		if (!ASSERT_EQ(id, 6, "btf__add_decl_tag contains:bar:b"))
+			break;
+		id = btf__add_struct(btf, "bar", 36);
+		if (!ASSERT_EQ(id, 7, "btf__add_struct bar"))
+			break;
+		err = btf__add_field(btf, "a", LIST_HEAD, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field bar::a"))
+			break;
+		err = btf__add_field(btf, "b", LIST_NODE, 128, 0);
+		if (!ASSERT_OK(err, "btf__add_field bar::b"))
+			break;
+		err = btf__add_field(btf, "c", SPIN_LOCK, 256, 0);
+		if (!ASSERT_OK(err, "btf__add_field bar::c"))
+			break;
+		id = btf__add_decl_tag(btf, "contains:baz:a", 7, 0);
+		if (!ASSERT_EQ(id, 8, "btf__add_decl_tag contains:baz:a"))
+			break;
+		id = btf__add_struct(btf, "baz", 16);
+		if (!ASSERT_EQ(id, 9, "btf__add_struct baz"))
+			break;
+		err = btf__add_field(btf, "a", LIST_NODE, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field baz:a"))
+			break;
+
+		err = btf__load_into_kernel(btf);
+		ASSERT_EQ(err, 0, "check btf");
+		btf__free(btf);
+		break;
+	}
+
+	while (test__start_subtest("btf: owning | owned -> owning | owned -> owned")) {
+		btf = init_btf();
+		if (!ASSERT_OK_PTR(btf, "init_btf"))
+			break;
+		id = btf__add_struct(btf, "foo", 36);
+		if (!ASSERT_EQ(id, 5, "btf__add_struct foo"))
+			break;
+		err = btf__add_field(btf, "a", LIST_HEAD, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::a"))
+			break;
+		err = btf__add_field(btf, "b", LIST_NODE, 128, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::b"))
+			break;
+		err = btf__add_field(btf, "c", SPIN_LOCK, 256, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::c"))
+			break;
+		id = btf__add_decl_tag(btf, "contains:bar:b", 5, 0);
+		if (!ASSERT_EQ(id, 6, "btf__add_decl_tag contains:bar:b"))
+			break;
+		id = btf__add_struct(btf, "bar", 36);
+		if (!ASSERT_EQ(id, 7, "btf__add_struct bar"))
+			break;
+		err = btf__add_field(btf, "a", LIST_HEAD, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field bar:a"))
+			break;
+		err = btf__add_field(btf, "b", LIST_NODE, 128, 0);
+		if (!ASSERT_OK(err, "btf__add_field bar:b"))
+			break;
+		err = btf__add_field(btf, "c", SPIN_LOCK, 256, 0);
+		if (!ASSERT_OK(err, "btf__add_field bar:c"))
+			break;
+		id = btf__add_decl_tag(btf, "contains:baz:a", 7, 0);
+		if (!ASSERT_EQ(id, 8, "btf__add_decl_tag contains:baz:a"))
+			break;
+		id = btf__add_struct(btf, "baz", 16);
+		if (!ASSERT_EQ(id, 9, "btf__add_struct baz"))
+			break;
+		err = btf__add_field(btf, "a", LIST_NODE, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field baz:a"))
+			break;
+
+		err = btf__load_into_kernel(btf);
+		ASSERT_EQ(err, -ELOOP, "check btf");
+		btf__free(btf);
+		break;
+	}
+
+	while (test__start_subtest("btf: owning -> owning | owned -> owning | owned -> owned")) {
+		btf = init_btf();
+		if (!ASSERT_OK_PTR(btf, "init_btf"))
+			break;
+		id = btf__add_struct(btf, "foo", 20);
+		if (!ASSERT_EQ(id, 5, "btf__add_struct foo"))
+			break;
+		err = btf__add_field(btf, "a", LIST_HEAD, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::a"))
+			break;
+		err = btf__add_field(btf, "b", SPIN_LOCK, 128, 0);
+		if (!ASSERT_OK(err, "btf__add_field foo::b"))
+			break;
+		id = btf__add_decl_tag(btf, "contains:bar:b", 5, 0);
+		if (!ASSERT_EQ(id, 6, "btf__add_decl_tag contains:bar:b"))
+			break;
+		id = btf__add_struct(btf, "bar", 36);
+		if (!ASSERT_EQ(id, 7, "btf__add_struct bar"))
+			break;
+		err = btf__add_field(btf, "a", LIST_HEAD, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field bar::a"))
+			break;
+		err = btf__add_field(btf, "b", LIST_NODE, 128, 0);
+		if (!ASSERT_OK(err, "btf__add_field bar::b"))
+			break;
+		err = btf__add_field(btf, "c", SPIN_LOCK, 256, 0);
+		if (!ASSERT_OK(err, "btf__add_field bar::c"))
+			break;
+		id = btf__add_decl_tag(btf, "contains:baz:b", 7, 0);
+		if (!ASSERT_EQ(id, 8, "btf__add_decl_tag"))
+			break;
+		id = btf__add_struct(btf, "baz", 36);
+		if (!ASSERT_EQ(id, 9, "btf__add_struct baz"))
+			break;
+		err = btf__add_field(btf, "a", LIST_HEAD, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field bar::a"))
+			break;
+		err = btf__add_field(btf, "b", LIST_NODE, 128, 0);
+		if (!ASSERT_OK(err, "btf__add_field bar::b"))
+			break;
+		err = btf__add_field(btf, "c", SPIN_LOCK, 256, 0);
+		if (!ASSERT_OK(err, "btf__add_field bar::c"))
+			break;
+		id = btf__add_decl_tag(btf, "contains:bam:a", 9, 0);
+		if (!ASSERT_EQ(id, 10, "btf__add_decl_tag contains:bam:a"))
+			break;
+		id = btf__add_struct(btf, "bam", 16);
+		if (!ASSERT_EQ(id, 11, "btf__add_struct bam"))
+			break;
+		err = btf__add_field(btf, "a", LIST_NODE, 0, 0);
+		if (!ASSERT_OK(err, "btf__add_field bam::a"))
+			break;
+
+		err = btf__load_into_kernel(btf);
+		ASSERT_EQ(err, -ELOOP, "check btf");
+		btf__free(btf);
+		break;
+	}
+}
+
 void test_linked_list(void)
 {
 	int i;
@@ -245,6 +729,7 @@ void test_linked_list(void)
 		test_linked_list_fail_prog(linked_list_fail_tests[i].prog_name,
 					   linked_list_fail_tests[i].err_msg);
 	}
+	test_btf();
 	test_linked_list_success(PUSH_POP, false);
 	test_linked_list_success(PUSH_POP, true);
 	test_linked_list_success(PUSH_POP_MULT, false);