From: Yuntao Wang ytcoode@gmail.com

[ Upstream commit b23316aabffa835ecc516cb81daeef5b9155e8a5 ]

Currently the trampoline_count test doesn't include any fmod_ret bpf programs, fix it to make the test cover all possible trampoline program types.

Since fmod_ret bpf programs can't be attached to __set_task_comm function, as it's neither whitelisted for error injection nor a security hook, change it to bpf_modify_return_test.

This patch also does some other cleanups such as removing duplicate code, dropping inconsistent comments, etc.

Signed-off-by: Yuntao Wang ytcoode@gmail.com Signed-off-by: Andrii Nakryiko andrii@kernel.org Acked-by: Yonghong Song yhs@fb.com Link: https://lore.kernel.org/bpf/20220519150610.601313-1-ytcoode@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/bpf.h | 2 +- .../bpf/prog_tests/trampoline_count.c | 134 +++++++----------- .../bpf/progs/test_trampoline_count.c | 16 ++- 3 files changed, 61 insertions(+), 91 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h index bdb5298735ce..f084b251fce7 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -672,7 +672,7 @@ struct btf_func_model { #define BPF_TRAMP_F_RET_FENTRY_RET BIT(4)

/* Each call __bpf_prog_enter + call bpf_func + call __bpf_prog_exit is ~50 - * bytes on x86. Pick a number to fit into BPF_IMAGE_SIZE / 2 + * bytes on x86. */ #define BPF_MAX_TRAMP_PROGS 38

diff --git a/tools/testing/selftests/bpf/prog_tests/trampoline_count.c b/tools/testing/selftests/bpf/prog_tests/trampoline_count.c index 9c795ee52b7b..b0acbda6dbf5 100644 --- a/tools/testing/selftests/bpf/prog_tests/trampoline_count.c +++ b/tools/testing/selftests/bpf/prog_tests/trampoline_count.c @@ -1,126 +1,94 @@ // SPDX-License-Identifier: GPL-2.0-only #define _GNU_SOURCE -#include <sched.h> -#include <sys/prctl.h> #include <test_progs.h>

#define MAX_TRAMP_PROGS 38

struct inst { struct bpf_object *obj; - struct bpf_link *link_fentry; - struct bpf_link *link_fexit; + struct bpf_link *link; };

-static int test_task_rename(void) -{ - int fd, duration = 0, err; - char buf[] = "test_overhead"; - - fd = open("/proc/self/comm", O_WRONLY|O_TRUNC); - if (CHECK(fd < 0, "open /proc", "err %d", errno)) - return -1; - err = write(fd, buf, sizeof(buf)); - if (err < 0) { - CHECK(err < 0, "task rename", "err %d", errno); - close(fd); - return -1; - } - close(fd); - return 0; -} - -static struct bpf_link *load(struct bpf_object *obj, const char *name) +static struct bpf_program *load_prog(char *file, char *name, struct inst *inst) { + struct bpf_object *obj; struct bpf_program *prog; - int duration = 0; + int err; + + obj = bpf_object__open_file(file, NULL); + if (!ASSERT_OK_PTR(obj, "obj_open_file")) + return NULL; + + inst->obj = obj; + + err = bpf_object__load(obj); + if (!ASSERT_OK(err, "obj_load")) + return NULL;

prog = bpf_object__find_program_by_name(obj, name); - if (CHECK(!prog, "find_probe", "prog '%s' not found\n", name)) - return ERR_PTR(-EINVAL); - return bpf_program__attach_trace(prog); + if (!ASSERT_OK_PTR(prog, "obj_find_prog")) + return NULL; + + return prog; }

/* TODO: use different target function to run in concurrent mode */ void serial_test_trampoline_count(void) { - const char *fentry_name = "prog1"; - const char *fexit_name = "prog2"; - const char *object = "test_trampoline_count.o"; - struct inst inst[MAX_TRAMP_PROGS] = {}; - int err, i = 0, duration = 0; - struct bpf_object *obj; + char *file = "test_trampoline_count.o"; + char *const progs[] = { "fentry_test", "fmod_ret_test", "fexit_test" }; + struct inst inst[MAX_TRAMP_PROGS + 1] = {}; + struct bpf_program *prog; struct bpf_link *link; - char comm[16] = {}; + int prog_fd, err, i; + LIBBPF_OPTS(bpf_test_run_opts, opts);

/* attach 'allowed' trampoline programs */ for (i = 0; i < MAX_TRAMP_PROGS; i++) { - obj = bpf_object__open_file(object, NULL); - if (!ASSERT_OK_PTR(obj, "obj_open_file")) { - obj = NULL; + prog = load_prog(file, progs[i % ARRAY_SIZE(progs)], &inst[i]); + if (!prog) goto cleanup; - }

- err = bpf_object__load(obj); - if (CHECK(err, "obj_load", "err %d\n", err)) + link = bpf_program__attach(prog); + if (!ASSERT_OK_PTR(link, "attach_prog")) goto cleanup; - inst[i].obj = obj; - obj = NULL; - - if (rand() % 2) { - link = load(inst[i].obj, fentry_name); - if (!ASSERT_OK_PTR(link, "attach_prog")) { - link = NULL; - goto cleanup; - } - inst[i].link_fentry = link; - } else { - link = load(inst[i].obj, fexit_name); - if (!ASSERT_OK_PTR(link, "attach_prog")) { - link = NULL; - goto cleanup; - } - inst[i].link_fexit = link; - } + + inst[i].link = link; }

/* and try 1 extra.. */ - obj = bpf_object__open_file(object, NULL); - if (!ASSERT_OK_PTR(obj, "obj_open_file")) { - obj = NULL; + prog = load_prog(file, "fmod_ret_test", &inst[i]); + if (!prog) goto cleanup; - } - - err = bpf_object__load(obj); - if (CHECK(err, "obj_load", "err %d\n", err)) - goto cleanup_extra;

/* ..that needs to fail */ - link = load(obj, fentry_name); - err = libbpf_get_error(link); - if (!ASSERT_ERR_PTR(link, "cannot attach over the limit")) { - bpf_link__destroy(link); - goto cleanup_extra; + link = bpf_program__attach(prog); + if (!ASSERT_ERR_PTR(link, "attach_prog")) { + inst[i].link = link; + goto cleanup; }

/* with E2BIG error */ - ASSERT_EQ(err, -E2BIG, "proper error check"); - ASSERT_EQ(link, NULL, "ptr_is_null"); + if (!ASSERT_EQ(libbpf_get_error(link), -E2BIG, "E2BIG")) + goto cleanup; + if (!ASSERT_EQ(link, NULL, "ptr_is_null")) + goto cleanup;

/* and finaly execute the probe */ - if (CHECK_FAIL(prctl(PR_GET_NAME, comm, 0L, 0L, 0L))) - goto cleanup_extra; - CHECK_FAIL(test_task_rename()); - CHECK_FAIL(prctl(PR_SET_NAME, comm, 0L, 0L, 0L)); + prog_fd = bpf_program__fd(prog); + if (!ASSERT_GE(prog_fd, 0, "bpf_program__fd")) + goto cleanup; + + err = bpf_prog_test_run_opts(prog_fd, &opts); + if (!ASSERT_OK(err, "bpf_prog_test_run_opts")) + goto cleanup; + + ASSERT_EQ(opts.retval & 0xffff, 4, "bpf_modify_return_test.result"); + ASSERT_EQ(opts.retval >> 16, 1, "bpf_modify_return_test.side_effect");

-cleanup_extra: - bpf_object__close(obj); cleanup: - if (i >= MAX_TRAMP_PROGS) - i = MAX_TRAMP_PROGS - 1; for (; i >= 0; i--) { - bpf_link__destroy(inst[i].link_fentry); - bpf_link__destroy(inst[i].link_fexit); + bpf_link__destroy(inst[i].link); bpf_object__close(inst[i].obj); } } diff --git a/tools/testing/selftests/bpf/progs/test_trampoline_count.c b/tools/testing/selftests/bpf/progs/test_trampoline_count.c index f030e469d05b..7765720da7d5 100644 --- a/tools/testing/selftests/bpf/progs/test_trampoline_count.c +++ b/tools/testing/selftests/bpf/progs/test_trampoline_count.c @@ -1,20 +1,22 @@ // SPDX-License-Identifier: GPL-2.0 -#include <stdbool.h> -#include <stddef.h> #include <linux/bpf.h> #include <bpf/bpf_helpers.h> #include <bpf/bpf_tracing.h>

-struct task_struct; +SEC("fentry/bpf_modify_return_test") +int BPF_PROG(fentry_test, int a, int *b) +{ + return 0; +}

-SEC("fentry/__set_task_comm") -int BPF_PROG(prog1, struct task_struct *tsk, const char *buf, bool exec) +SEC("fmod_ret/bpf_modify_return_test") +int BPF_PROG(fmod_ret_test, int a, int *b, int ret) { return 0; }

-SEC("fexit/__set_task_comm") -int BPF_PROG(prog2, struct task_struct *tsk, const char *buf, bool exec) +SEC("fexit/bpf_modify_return_test") +int BPF_PROG(fexit_test, int a, int *b, int ret) { return 0; }