On Wed, Dec 20, 2023 at 07:04:17PM +0100, Dmitrii Dolgov wrote:
> Verify the fact that only one fentry prog could be attached to another
> fentry, building up an attachment chain of limited size. Use existing
> bpf_testmod as a start of the chain.
>
> Signed-off-by: Dmitrii Dolgov <9erthalion6@xxxxxxxxx>
> ---
> Changes in v10:
> - Add tests for loading tracing progs without attaching, and
> detaching tracing progs.
>
> Changes in v8:
> - Cleanup test bpf progs and the content of first/second condition
> in the loop.
>
> Changes in v5:
> - Test only one level of attachment
>
> .../bpf/prog_tests/recursive_attach.c | 192 ++++++++++++++++++
> .../selftests/bpf/progs/fentry_recursive.c | 16 ++
> .../bpf/progs/fentry_recursive_target.c | 17 ++
> 3 files changed, 225 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/prog_tests/recursive_attach.c
> create mode 100644 tools/testing/selftests/bpf/progs/fentry_recursive.c
> create mode 100644 tools/testing/selftests/bpf/progs/fentry_recursive_target.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/recursive_attach.c b/tools/testing/selftests/bpf/prog_tests/recursive_attach.c
> new file mode 100644
> index 000000000000..4b46dc358925
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/recursive_attach.c
> @@ -0,0 +1,192 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2023 Red Hat, Inc. */
> +#include <test_progs.h>
> +#include "fentry_recursive.skel.h"
> +#include "fentry_recursive_target.skel.h"
> +#include <bpf/btf.h>
> +#include "bpf/libbpf_internal.h"
> +
> +/*
> + * Test that recursive attachment of tracing progs with more than one nesting
> + * level is not possible. Create a chain of attachment, verify that the last
> + * prog will fail.
> + */
> +void test_recursive_fentry_attach(void)
> +{
please use subtests for multiple tests in one object,
check for example the test_kprobe_multi_test
jirka
> + struct fentry_recursive_target *target_skel = NULL;
> + struct fentry_recursive *tracing_chain[2] = {};
> + struct bpf_program *prog;
> + int prev_fd, err;
> +
> + target_skel = fentry_recursive_target__open_and_load();
> + if (!ASSERT_OK_PTR(target_skel, "fentry_recursive_target__open_and_load"))
> + goto close_prog;
> +
> + /* Create an attachment chain with two fentry progs */
> + for (int i = 0; i < 2; i++) {
> + tracing_chain[i] = fentry_recursive__open();
> + if (!ASSERT_OK_PTR(tracing_chain[i], "fentry_recursive__open"))
> + goto close_prog;
> +
> + /*
> + * The first prog in the chain is going to be attached to the target
> + * fentry program, the second one to the previous in the chain.
> + */
> + prog = tracing_chain[i]->progs.recursive_attach;
> + if (i == 0) {
> + prev_fd = bpf_program__fd(target_skel->progs.test1);
> + err = bpf_program__set_attach_target(prog, prev_fd, "test1");
> + } else {
> + prev_fd = bpf_program__fd(tracing_chain[i-1]->progs.recursive_attach);
> + err = bpf_program__set_attach_target(prog, prev_fd, "recursive_attach");
> + }
> +
> + if (!ASSERT_OK(err, "bpf_program__set_attach_target"))
> + goto close_prog;
> +
> + err = fentry_recursive__load(tracing_chain[i]);
> + /* The first attach should succeed, the second fail */
> + if (i == 0) {
> + if (!ASSERT_OK(err, "fentry_recursive__load"))
> + goto close_prog;
> +
> + err = fentry_recursive__attach(tracing_chain[i]);
> + if (!ASSERT_OK(err, "fentry_recursive__attach"))
> + goto close_prog;
> + } else {
> + if (!ASSERT_ERR(err, "fentry_recursive__load"))
> + goto close_prog;
> + }
> + }
> +
> +close_prog:
> + fentry_recursive_target__destroy(target_skel);
> + for (int i = 0; i < 2; i++) {
> + if (tracing_chain[i])
> + fentry_recursive__destroy(tracing_chain[i]);
> + }
> +}
> +
> +/*
> + * Test that recursive loading of tracing progs with more than one nesting
> + * level is not possible either. Identical to the previous one, but without
> + * fentry attach.
> + */
> +void test_recursive_fentry_load(void)
> +{
> + struct fentry_recursive_target *target_skel = NULL;
> + struct fentry_recursive *tracing_chain[2] = {};
> + struct bpf_program *prog;
> + int prev_fd, err;
> +
> + target_skel = fentry_recursive_target__open_and_load();
> + if (!ASSERT_OK_PTR(target_skel, "fentry_recursive_target__open_and_load"))
> + goto close_prog;
> +
> + /* Create an attachment chain with two fentry progs */
> + for (int i = 0; i < 2; i++) {
> + tracing_chain[i] = fentry_recursive__open();
> + if (!ASSERT_OK_PTR(tracing_chain[i], "fentry_recursive__open"))
> + goto close_prog;
> +
> + /*
> + * The first prog in the chain is going to be attached to the target
> + * fentry program, the second one to the previous in the chain.
> + */
> + prog = tracing_chain[i]->progs.recursive_attach;
> + if (i == 0) {
> + prev_fd = bpf_program__fd(target_skel->progs.test1);
> + err = bpf_program__set_attach_target(prog, prev_fd, "test1");
> + } else {
> + prev_fd = bpf_program__fd(tracing_chain[i-1]->progs.recursive_attach);
> + err = bpf_program__set_attach_target(prog, prev_fd, "recursive_attach");
> + }
> +
> + if (!ASSERT_OK(err, "bpf_program__set_attach_target"))
> + goto close_prog;
> +
> + err = fentry_recursive__load(tracing_chain[i]);
> + /* The first attach should succeed, the second fail */
> + if (i == 0) {
> + if (!ASSERT_OK(err, "fentry_recursive__load"))
> + goto close_prog;
> + } else {
> + if (!ASSERT_ERR(err, "fentry_recursive__load"))
> + goto close_prog;
> + }
> + }
> +
> +close_prog:
> + fentry_recursive_target__destroy(target_skel);
> + for (int i = 0; i < 2; i++) {
> + if (tracing_chain[i])
> + fentry_recursive__destroy(tracing_chain[i]);
> + }
> +}
> +
> +/*
> + * Test that attach_tracing_prog flag will be set throughout the whole
> + * lifecycle of an fentry prog, independently from whether it's detached.
> + */
> +void test_recursive_fentry_detach(void)
> +{
> + struct fentry_recursive_target *target_skel = NULL;
> + struct fentry_recursive *tracing_chain[2] = {};
> + struct bpf_program *prog;
> + int prev_fd, err;
> +
> + /* Load the target fentry */
> + target_skel = fentry_recursive_target__open_and_load();
> + if (!ASSERT_OK_PTR(target_skel, "fentry_recursive_target__open_and_load"))
> + goto close_prog;
> +
> + /* Create an attachment chain with two fentry progs */
> + for (int i = 0; i < 2; i++) {
> + tracing_chain[i] = fentry_recursive__open();
> + if (!ASSERT_OK_PTR(tracing_chain[i], "fentry_recursive__open"))
> + goto close_prog;
> +
> + /*
> + * The first prog in the chain is going to be attached to the target
> + * fentry program, the second one to the previous in the chain.
> + */
> + prog = tracing_chain[i]->progs.recursive_attach;
> + if (i == 0) {
> + prev_fd = bpf_program__fd(target_skel->progs.test1);
> + err = bpf_program__set_attach_target(prog, prev_fd, "test1");
> + } else {
> + prev_fd = bpf_program__fd(tracing_chain[i-1]->progs.recursive_attach);
> + err = bpf_program__set_attach_target(prog, prev_fd, "recursive_attach");
> + }
> +
> + if (!ASSERT_OK(err, "bpf_program__set_attach_target"))
> + goto close_prog;
> +
> + err = fentry_recursive__load(tracing_chain[i]);
> + /* The first attach should succeed, the second fail */
> + if (i == 0) {
> + if (!ASSERT_OK(err, "fentry_recursive__load"))
> + goto close_prog;
> +
> + err = fentry_recursive__attach(tracing_chain[i]);
> + if (!ASSERT_OK(err, "fentry_recursive__attach"))
> + goto close_prog;
> +
> + /*
> + * Flag attach_tracing_prog should still be set, preventing
> + * attachment of the following prog.
> + */
> + fentry_recursive__detach(tracing_chain[i]);
> + } else {
> + if (!ASSERT_ERR(err, "fentry_recursive__load"))
> + goto close_prog;
> + }
> + }
> +
> +close_prog:
> + fentry_recursive_target__destroy(target_skel);
> + for (int i = 0; i < 2; i++) {
> + if (tracing_chain[i])
> + fentry_recursive__destroy(tracing_chain[i]);
> + }
> +}
> diff --git a/tools/testing/selftests/bpf/progs/fentry_recursive.c b/tools/testing/selftests/bpf/progs/fentry_recursive.c
> new file mode 100644
> index 000000000000..b9e4d35ac597
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/fentry_recursive.c
> @@ -0,0 +1,16 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2023 Red Hat, Inc. */
> +#include <linux/bpf.h>
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +
> +char _license[] SEC("license") = "GPL";
> +
> +/*
> + * Dummy fentry bpf prog for testing fentry attachment chains
> + */
> +SEC("fentry/XXX")
> +int BPF_PROG(recursive_attach, int a)
> +{
> + return 0;
> +}
> diff --git a/tools/testing/selftests/bpf/progs/fentry_recursive_target.c b/tools/testing/selftests/bpf/progs/fentry_recursive_target.c
> new file mode 100644
> index 000000000000..6e0b5c716f8e
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/fentry_recursive_target.c
> @@ -0,0 +1,17 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2023 Red Hat, Inc. */
> +#include <linux/bpf.h>
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +
> +char _license[] SEC("license") = "GPL";
> +
> +/*
> + * Dummy fentry bpf prog for testing fentry attachment chains. It's going to be
> + * a start of the chain.
> + */
> +SEC("fentry/bpf_testmod_fentry_test1")
> +int BPF_PROG(test1, int a)
> +{
> + return 0;
> +}
> --
> 2.41.0
>
