Add a selftest validating various aspects of libbpf's handling of custom SEC() handlers. It also demonstrates how libraries can ensure very early callbacks registration and unregistration using __attribute__((constructor))/__attribute__((destructor)) functions. Reviewed-by: Alan Maguire <alan.maguire@xxxxxxxxxx> Tested-by: Alan Maguire <alan.maguire@xxxxxxxxxx> Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx> --- .../bpf/prog_tests/custom_sec_handlers.c | 176 ++++++++++++++++++ .../bpf/progs/test_custom_sec_handlers.c | 63 +++++++ 2 files changed, 239 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/custom_sec_handlers.c create mode 100644 tools/testing/selftests/bpf/progs/test_custom_sec_handlers.c diff --git a/tools/testing/selftests/bpf/prog_tests/custom_sec_handlers.c b/tools/testing/selftests/bpf/prog_tests/custom_sec_handlers.c new file mode 100644 index 000000000000..b2dfc5954aea --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/custom_sec_handlers.c @@ -0,0 +1,176 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2022 Facebook */ + +#include <test_progs.h> +#include "test_custom_sec_handlers.skel.h" + +#define COOKIE_ABC1 1 +#define COOKIE_ABC2 2 +#define COOKIE_CUSTOM 3 +#define COOKIE_FALLBACK 4 +#define COOKIE_KPROBE 5 + +static int custom_setup_prog(struct bpf_program *prog, long cookie) +{ + if (cookie == COOKIE_ABC1) + bpf_program__set_autoload(prog, false); + + return 0; +} + +static int custom_prepare_load_prog(struct bpf_program *prog, + struct bpf_prog_load_opts *opts, long cookie) +{ + if (cookie == COOKIE_FALLBACK) + opts->prog_flags |= BPF_F_SLEEPABLE; + else if (cookie == COOKIE_ABC1) + ASSERT_FALSE(true, "unexpected preload for abc"); + + return 0; +} + +static int custom_attach_prog(const struct bpf_program *prog, long cookie, + struct bpf_link **link) +{ + switch (cookie) { + case COOKIE_ABC2: + *link = bpf_program__attach_raw_tracepoint(prog, "sys_enter"); + return libbpf_get_error(*link); + case COOKIE_CUSTOM: + *link = bpf_program__attach_tracepoint(prog, "syscalls", "sys_enter_nanosleep"); + return libbpf_get_error(*link); + case COOKIE_KPROBE: + case COOKIE_FALLBACK: + /* no auto-attach for SEC("xyz") and SEC("kprobe") */ + *link = NULL; + return 0; + default: + ASSERT_FALSE(true, "unexpected cookie"); + return -EINVAL; + } +} + +static int abc1_id; +static int abc2_id; +static int custom_id; +static int fallback_id; +static int kprobe_id; + +__attribute__((constructor)) +static void register_sec_handlers(void) +{ + LIBBPF_OPTS(libbpf_prog_handler_opts, abc1_opts, + .cookie = COOKIE_ABC1, + .prog_setup_fn = custom_setup_prog, + .prog_prepare_load_fn = custom_prepare_load_prog, + .prog_attach_fn = NULL, + ); + LIBBPF_OPTS(libbpf_prog_handler_opts, abc2_opts, + .cookie = COOKIE_ABC2, + .prog_setup_fn = custom_setup_prog, + .prog_prepare_load_fn = custom_prepare_load_prog, + .prog_attach_fn = custom_attach_prog, + ); + LIBBPF_OPTS(libbpf_prog_handler_opts, custom_opts, + .cookie = COOKIE_CUSTOM, + .prog_setup_fn = NULL, + .prog_prepare_load_fn = NULL, + .prog_attach_fn = custom_attach_prog, + ); + + abc1_id = libbpf_register_prog_handler("abc", BPF_PROG_TYPE_RAW_TRACEPOINT, 0, &abc1_opts); + abc2_id = libbpf_register_prog_handler("abc/", BPF_PROG_TYPE_RAW_TRACEPOINT, 0, &abc2_opts); + custom_id = libbpf_register_prog_handler("custom+", BPF_PROG_TYPE_TRACEPOINT, 0, &custom_opts); +} + +__attribute__((destructor)) +static void unregister_sec_handlers(void) +{ + libbpf_unregister_prog_handler(abc1_id); + libbpf_unregister_prog_handler(abc2_id); + libbpf_unregister_prog_handler(custom_id); +} + +void test_custom_sec_handlers(void) +{ + LIBBPF_OPTS(libbpf_prog_handler_opts, opts, + .prog_setup_fn = custom_setup_prog, + .prog_prepare_load_fn = custom_prepare_load_prog, + .prog_attach_fn = custom_attach_prog, + ); + struct test_custom_sec_handlers* skel; + int err; + + ASSERT_GT(abc1_id, 0, "abc1_id"); + ASSERT_GT(abc2_id, 0, "abc2_id"); + ASSERT_GT(custom_id, 0, "custom_id"); + + /* override libbpf's handle of SEC("kprobe/...") but also allow pure + * SEC("kprobe") due to "kprobe+" specifier. Register it as + * TRACEPOINT, just for fun. + */ + opts.cookie = COOKIE_KPROBE; + kprobe_id = libbpf_register_prog_handler("kprobe+", BPF_PROG_TYPE_TRACEPOINT, 0, &opts); + /* fallback treats everything as BPF_PROG_TYPE_SYSCALL program to test + * setting custom BPF_F_SLEEPABLE bit in preload handler + */ + opts.cookie = COOKIE_FALLBACK; + fallback_id = libbpf_register_prog_handler(NULL, BPF_PROG_TYPE_SYSCALL, 0, &opts); + + if (!ASSERT_GT(fallback_id, 0, "fallback_id") /* || !ASSERT_GT(kprobe_id, 0, "kprobe_id")*/) { + if (fallback_id > 0) + libbpf_unregister_prog_handler(fallback_id); + if (kprobe_id > 0) + libbpf_unregister_prog_handler(kprobe_id); + return; + } + + /* open skeleton and validate assumptions */ + skel = test_custom_sec_handlers__open(); + if (!ASSERT_OK_PTR(skel, "skel_open")) + goto cleanup; + + ASSERT_EQ(bpf_program__type(skel->progs.abc1), BPF_PROG_TYPE_RAW_TRACEPOINT, "abc1_type"); + ASSERT_FALSE(bpf_program__autoload(skel->progs.abc1), "abc1_autoload"); + + ASSERT_EQ(bpf_program__type(skel->progs.abc2), BPF_PROG_TYPE_RAW_TRACEPOINT, "abc2_type"); + ASSERT_EQ(bpf_program__type(skel->progs.custom1), BPF_PROG_TYPE_TRACEPOINT, "custom1_type"); + ASSERT_EQ(bpf_program__type(skel->progs.custom2), BPF_PROG_TYPE_TRACEPOINT, "custom2_type"); + ASSERT_EQ(bpf_program__type(skel->progs.kprobe1), BPF_PROG_TYPE_TRACEPOINT, "kprobe1_type"); + ASSERT_EQ(bpf_program__type(skel->progs.xyz), BPF_PROG_TYPE_SYSCALL, "xyz_type"); + + skel->rodata->my_pid = getpid(); + + /* now attempt to load everything */ + err = test_custom_sec_handlers__load(skel); + if (!ASSERT_OK(err, "skel_load")) + goto cleanup; + + /* now try to auto-attach everything */ + err = test_custom_sec_handlers__attach(skel); + if (!ASSERT_OK(err, "skel_attach")) + goto cleanup; + + skel->links.xyz = bpf_program__attach(skel->progs.kprobe1); + ASSERT_EQ(errno, EOPNOTSUPP, "xyz_attach_err"); + ASSERT_ERR_PTR(skel->links.xyz, "xyz_attach"); + + /* trigger programs */ + usleep(1); + + /* SEC("abc") is set to not auto-loaded */ + ASSERT_FALSE(skel->bss->abc1_called, "abc1_called"); + ASSERT_TRUE(skel->bss->abc2_called, "abc2_called"); + ASSERT_TRUE(skel->bss->custom1_called, "custom1_called"); + ASSERT_TRUE(skel->bss->custom2_called, "custom2_called"); + /* SEC("kprobe") shouldn't be auto-attached */ + ASSERT_FALSE(skel->bss->kprobe1_called, "kprobe1_called"); + /* SEC("xyz") shouldn't be auto-attached */ + ASSERT_FALSE(skel->bss->xyz_called, "xyz_called"); + +cleanup: + test_custom_sec_handlers__destroy(skel); + + ASSERT_OK(libbpf_unregister_prog_handler(fallback_id), "unregister_fallback"); + ASSERT_OK(libbpf_unregister_prog_handler(kprobe_id), "unregister_kprobe"); +} diff --git a/tools/testing/selftests/bpf/progs/test_custom_sec_handlers.c b/tools/testing/selftests/bpf/progs/test_custom_sec_handlers.c new file mode 100644 index 000000000000..4061f701ca50 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_custom_sec_handlers.c @@ -0,0 +1,63 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2022 Facebook */ + +#include "vmlinux.h" +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> + +const volatile int my_pid; + +bool abc1_called; +bool abc2_called; +bool custom1_called; +bool custom2_called; +bool kprobe1_called; +bool xyz_called; + +SEC("abc") +int abc1(void *ctx) +{ + abc1_called = true; + return 0; +} + +SEC("abc/whatever") +int abc2(void *ctx) +{ + abc2_called = true; + return 0; +} + +SEC("custom") +int custom1(void *ctx) +{ + custom1_called = true; + return 0; +} + +SEC("custom/something") +int custom2(void *ctx) +{ + custom2_called = true; + return 0; +} + +SEC("kprobe") +int kprobe1(void *ctx) +{ + kprobe1_called = true; + return 0; +} + +SEC("xyz/blah") +int xyz(void *ctx) +{ + int whatever; + + /* use sleepable helper, custom handler should set sleepable flag */ + bpf_copy_from_user(&whatever, sizeof(whatever), NULL); + xyz_called = true; + return 0; +} + +char _license[] SEC("license") = "GPL"; -- 2.30.2