diff mbox series

[bpf-next,v3,06/15] selftests/bpf: bad_struct_ops test

Message ID 20240304225156.24765-7-eddyz87@gmail.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series libbpf: type suffixes and autocreate flag for struct_ops maps | expand

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Commit Message

Eduard Zingerman March 4, 2024, 10:51 p.m. UTC 
When loading struct_ops programs kernel requires BTF id of the
struct_ops type and member index for attachment point inside that
type. This makes it not possible to have same BPF program used in
struct_ops maps that have different struct_ops type.
Check if libbpf rejects such BPF objects files.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
---
 .../selftests/bpf/bpf_testmod/bpf_testmod.c   | 24 +++++++++++++
 .../selftests/bpf/bpf_testmod/bpf_testmod.h   |  4 +++
 .../selftests/bpf/prog_tests/bad_struct_ops.c | 35 +++++++++++++++++++
 .../selftests/bpf/progs/bad_struct_ops.c      | 25 +++++++++++++
 4 files changed, 88 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/bad_struct_ops.c
 create mode 100644 tools/testing/selftests/bpf/progs/bad_struct_ops.c

Comments

Andrii Nakryiko March 5, 2024, 7:29 p.m. UTC | #1 
On Mon, Mar 4, 2024 at 2:52 PM Eduard Zingerman <eddyz87@gmail.com> wrote:
>
> When loading struct_ops programs kernel requires BTF id of the
> struct_ops type and member index for attachment point inside that
> type. This makes it not possible to have same BPF program used in
> struct_ops maps that have different struct_ops type.
> Check if libbpf rejects such BPF objects files.
>
> Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
> ---
>  .../selftests/bpf/bpf_testmod/bpf_testmod.c   | 24 +++++++++++++
>  .../selftests/bpf/bpf_testmod/bpf_testmod.h   |  4 +++
>  .../selftests/bpf/prog_tests/bad_struct_ops.c | 35 +++++++++++++++++++
>  .../selftests/bpf/progs/bad_struct_ops.c      | 25 +++++++++++++
>  4 files changed, 88 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/bad_struct_ops.c
>  create mode 100644 tools/testing/selftests/bpf/progs/bad_struct_ops.c
>

CI reports kernel crashes, so please check that, but overall things look good:

Acked-by: Andrii Nakryiko <andrii@kernel.org>

> diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> index b9ff88e3d463..2de7e80dbb4b 100644
> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> @@ -610,6 +610,29 @@ struct bpf_struct_ops bpf_bpf_testmod_ops = {
>         .owner = THIS_MODULE,
>  };
>

[...]

> diff --git a/tools/testing/selftests/bpf/prog_tests/bad_struct_ops.c b/tools/testing/selftests/bpf/prog_tests/bad_struct_ops.c
> new file mode 100644
> index 000000000000..9f5dbefa0dd9
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/bad_struct_ops.c
> @@ -0,0 +1,35 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <test_progs.h>
> +#include "bad_struct_ops.skel.h"
> +
> +static void invalid_prog_reuse(void)
> +{
> +       struct bad_struct_ops *skel;
> +       char *log = NULL;
> +       int err;
> +
> +       skel = bad_struct_ops__open();
> +       if (!ASSERT_OK_PTR(skel, "bad_struct_ops__open"))
> +               return;
> +
> +       if (start_libbpf_log_capture())
> +               goto cleanup;
> +
> +       err = bad_struct_ops__load(skel);
> +       log = stop_libbpf_log_capture();
> +       ASSERT_ERR(err, "bad_struct_ops__load should fail");

second argument isn't actually a test description, it's meant to be
used as a (relatively) short identifier of *what* is being checked
(see how ASSERT_xxx() macro are using them)

> +       ASSERT_HAS_SUBSTR(log,
> +               "struct_ops init_kern testmod_2 func ptr test_1: invalid reuse of prog test_1",
> +               "expected init_kern message");
> +
> +cleanup:
> +       free(log);
> +       bad_struct_ops__destroy(skel);
> +}
> +
> +void test_bad_struct_ops(void)
> +{
> +       if (test__start_subtest("invalid_prog_reuse"))
> +               invalid_prog_reuse();
> +}

[...]
Eduard Zingerman March 6, 2024, 12:05 a.m. UTC | #2 
On Tue, 2024-03-05 at 11:29 -0800, Andrii Nakryiko wrote:
> On Mon, Mar 4, 2024 at 2:52 PM Eduard Zingerman <eddyz87@gmail.com> wrote:
> > 
> > When loading struct_ops programs kernel requires BTF id of the
> > struct_ops type and member index for attachment point inside that
> > type. This makes it not possible to have same BPF program used in
> > struct_ops maps that have different struct_ops type.
> > Check if libbpf rejects such BPF objects files.
> > 
> > Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
> > ---
> >  .../selftests/bpf/bpf_testmod/bpf_testmod.c   | 24 +++++++++++++
> >  .../selftests/bpf/bpf_testmod/bpf_testmod.h   |  4 +++
> >  .../selftests/bpf/prog_tests/bad_struct_ops.c | 35 +++++++++++++++++++
> >  .../selftests/bpf/progs/bad_struct_ops.c      | 25 +++++++++++++
> >  4 files changed, 88 insertions(+)
> >  create mode 100644 tools/testing/selftests/bpf/prog_tests/bad_struct_ops.c
> >  create mode 100644 tools/testing/selftests/bpf/progs/bad_struct_ops.c
> > 
> 
> CI reports kernel crashes, so please check that, but overall things look good:
> 
> Acked-by: Andrii Nakryiko <andrii@kernel.org>

Newly added test case struct_ops_multi_pages does not define
bpf_testmod_ops->test_1 field for struct_ops map,
so the following code from my patch caused null pointer dereference:

       563  static int bpf_dummy_reg(void *kdata)
       564  {
       565          struct bpf_testmod_ops *ops = kdata;
       566
       567          ops->test_1();

Fixed by adding "if (ops)" check.

[...]
diff mbox series

Patch

diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
index b9ff88e3d463..2de7e80dbb4b 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
@@ -610,6 +610,29 @@  struct bpf_struct_ops bpf_bpf_testmod_ops = {
 	.owner = THIS_MODULE,
 };
 
+static int bpf_dummy_reg2(void *kdata)
+{
+	struct bpf_testmod_ops2 *ops = kdata;
+
+	ops->test_1();
+	return 0;
+}
+
+static struct bpf_testmod_ops2 __bpf_testmod_ops2 = {
+	.test_1 = bpf_testmod_test_1,
+};
+
+struct bpf_struct_ops bpf_testmod_ops2 = {
+	.verifier_ops = &bpf_testmod_verifier_ops,
+	.init = bpf_testmod_ops_init,
+	.init_member = bpf_testmod_ops_init_member,
+	.reg = bpf_dummy_reg2,
+	.unreg = bpf_dummy_unreg,
+	.cfi_stubs = &__bpf_testmod_ops2,
+	.name = "bpf_testmod_ops2",
+	.owner = THIS_MODULE,
+};
+
 extern int bpf_fentry_test1(int a);
 
 static int bpf_testmod_init(void)
@@ -621,6 +644,7 @@  static int bpf_testmod_init(void)
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &bpf_testmod_kfunc_set);
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SYSCALL, &bpf_testmod_kfunc_set);
 	ret = ret ?: register_bpf_struct_ops(&bpf_bpf_testmod_ops, bpf_testmod_ops);
+	ret = ret ?: register_bpf_struct_ops(&bpf_testmod_ops2, bpf_testmod_ops2);
 	if (ret < 0)
 		return ret;
 	if (bpf_fentry_test1(0) < 0)
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
index 971458acfac3..c51c4eae9ed5 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
@@ -45,4 +45,8 @@  struct bpf_testmod_ops {
 	int data;
 };
 
+struct bpf_testmod_ops2 {
+	int (*test_1)(void);
+};
+
 #endif /* _BPF_TESTMOD_H */
diff --git a/tools/testing/selftests/bpf/prog_tests/bad_struct_ops.c b/tools/testing/selftests/bpf/prog_tests/bad_struct_ops.c
new file mode 100644
index 000000000000..9f5dbefa0dd9
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/bad_struct_ops.c
@@ -0,0 +1,35 @@ 
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+#include "bad_struct_ops.skel.h"
+
+static void invalid_prog_reuse(void)
+{
+	struct bad_struct_ops *skel;
+	char *log = NULL;
+	int err;
+
+	skel = bad_struct_ops__open();
+	if (!ASSERT_OK_PTR(skel, "bad_struct_ops__open"))
+		return;
+
+	if (start_libbpf_log_capture())
+		goto cleanup;
+
+	err = bad_struct_ops__load(skel);
+	log = stop_libbpf_log_capture();
+	ASSERT_ERR(err, "bad_struct_ops__load should fail");
+	ASSERT_HAS_SUBSTR(log,
+		"struct_ops init_kern testmod_2 func ptr test_1: invalid reuse of prog test_1",
+		"expected init_kern message");
+
+cleanup:
+	free(log);
+	bad_struct_ops__destroy(skel);
+}
+
+void test_bad_struct_ops(void)
+{
+	if (test__start_subtest("invalid_prog_reuse"))
+		invalid_prog_reuse();
+}
diff --git a/tools/testing/selftests/bpf/progs/bad_struct_ops.c b/tools/testing/selftests/bpf/progs/bad_struct_ops.c
new file mode 100644
index 000000000000..b7e175cd0af0
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bad_struct_ops.c
@@ -0,0 +1,25 @@ 
+// SPDX-License-Identifier: GPL-2.0
+
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "../bpf_testmod/bpf_testmod.h"
+
+char _license[] SEC("license") = "GPL";
+
+SEC("struct_ops/test_1")
+int BPF_PROG(test_1) { return 0; }
+
+SEC("struct_ops/test_2")
+int BPF_PROG(test_2) { return 0; }
+
+SEC(".struct_ops.link")
+struct bpf_testmod_ops testmod_1 = {
+	.test_1 = (void *)test_1,
+	.test_2 = (void *)test_2
+};
+
+SEC(".struct_ops.link")
+struct bpf_testmod_ops2 testmod_2 = {
+	.test_1 = (void *)test_1
+};