Commit fe147956 authored by David Vernet's avatar David Vernet Committed by Alexei Starovoitov
Browse files

bpf/selftests: Add selftests for new task kfuncs 



A previous change added a series of kfuncs for storing struct
task_struct objects as referenced kptrs. This patch adds a new
task_kfunc test suite for validating their expected behavior.

Signed-off-by: default avatarDavid Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20221120051004.3605026-5-void@manifault.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 90660309

tools/testing/selftests/bpf/DENYLIST.s390x

+1 −0
Original line number Diff line number Diff line
@@ -54,6 +54,7 @@ skc_to_unix_sock # could not attach BPF object unexpecte 
socket_cookie                            # prog_attach unexpected error: -524                                          (trampoline)

stacktrace_build_id                      # compare_map_keys stackid_hmap vs. stackmap err -2 errno 2                   (?)

tailcalls                                # tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls      (?)

task_kfunc                               # JIT does not support calling kernel function

task_local_storage                       # failed to auto-attach program 'trace_exit_creds': -524                      (trampoline)

test_bpffs                               # bpffs test  failed 255                                                      (iterator)

test_bprm_opts                           # failed to auto-attach program 'secure_exec': -524                           (trampoline)

tools/testing/selftests/bpf/prog_tests/task_kfunc.c

0 → 100644
+159 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */



#define _GNU_SOURCE

#include <sys/wait.h>

#include <test_progs.h>

#include <unistd.h>



#include "task_kfunc_failure.skel.h"

#include "task_kfunc_success.skel.h"



static size_t log_buf_sz = 1 << 20; /* 1 MB */

static char obj_log_buf[1048576];



static struct task_kfunc_success *open_load_task_kfunc_skel(void)

{

	struct task_kfunc_success *skel;

	int err;



	skel = task_kfunc_success__open();

	if (!ASSERT_OK_PTR(skel, "skel_open"))

		return NULL;



	skel->bss->pid = getpid();



	err = task_kfunc_success__load(skel);

	if (!ASSERT_OK(err, "skel_load"))

		goto cleanup;



	return skel;



cleanup:

	task_kfunc_success__destroy(skel);

	return NULL;

}



static void run_success_test(const char *prog_name)

{

	struct task_kfunc_success *skel;

	int status;

	pid_t child_pid;

	struct bpf_program *prog;

	struct bpf_link *link = NULL;



	skel = open_load_task_kfunc_skel();

	if (!ASSERT_OK_PTR(skel, "open_load_skel"))

		return;



	if (!ASSERT_OK(skel->bss->err, "pre_spawn_err"))

		goto cleanup;



	prog = bpf_object__find_program_by_name(skel->obj, prog_name);

	if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name"))

		goto cleanup;



	link = bpf_program__attach(prog);

	if (!ASSERT_OK_PTR(link, "attached_link"))

		goto cleanup;



	child_pid = fork();

	if (!ASSERT_GT(child_pid, -1, "child_pid"))

		goto cleanup;

	if (child_pid == 0)

		_exit(0);

	waitpid(child_pid, &status, 0);



	ASSERT_OK(skel->bss->err, "post_wait_err");



cleanup:

	bpf_link__destroy(link);

	task_kfunc_success__destroy(skel);

}



static const char * const success_tests[] = {

	"test_task_acquire_release_argument",

	"test_task_acquire_release_current",

	"test_task_acquire_leave_in_map",

	"test_task_xchg_release",

	"test_task_get_release",

	"test_task_current_acquire_release",

};



static struct {

	const char *prog_name;

	const char *expected_err_msg;

} failure_tests[] = {

	{"task_kfunc_acquire_untrusted", "R1 must be referenced or trusted"},

	{"task_kfunc_acquire_fp", "arg#0 pointer type STRUCT task_struct must point"},

	{"task_kfunc_acquire_unsafe_kretprobe", "reg type unsupported for arg#0 function"},

	{"task_kfunc_acquire_trusted_walked", "R1 must be referenced or trusted"},

	{"task_kfunc_acquire_null", "arg#0 pointer type STRUCT task_struct must point"},

	{"task_kfunc_acquire_unreleased", "Unreleased reference"},

	{"task_kfunc_get_non_kptr_param", "arg#0 expected pointer to map value"},

	{"task_kfunc_get_non_kptr_acquired", "arg#0 expected pointer to map value"},

	{"task_kfunc_get_null", "arg#0 expected pointer to map value"},

	{"task_kfunc_xchg_unreleased", "Unreleased reference"},

	{"task_kfunc_get_unreleased", "Unreleased reference"},

	{"task_kfunc_release_untrusted", "arg#0 is untrusted_ptr_or_null_ expected ptr_ or socket"},

	{"task_kfunc_release_fp", "arg#0 pointer type STRUCT task_struct must point"},

	{"task_kfunc_release_null", "arg#0 is ptr_or_null_ expected ptr_ or socket"},

	{"task_kfunc_release_unacquired", "release kernel function bpf_task_release expects"},

};



static void verify_fail(const char *prog_name, const char *expected_err_msg)

{

	LIBBPF_OPTS(bpf_object_open_opts, opts);

	struct task_kfunc_failure *skel;

	int err, i;



	opts.kernel_log_buf = obj_log_buf;

	opts.kernel_log_size = log_buf_sz;

	opts.kernel_log_level = 1;



	skel = task_kfunc_failure__open_opts(&opts);

	if (!ASSERT_OK_PTR(skel, "task_kfunc_failure__open_opts"))

		goto cleanup;



	for (i = 0; i < ARRAY_SIZE(failure_tests); i++) {

		struct bpf_program *prog;

		const char *curr_name = failure_tests[i].prog_name;



		prog = bpf_object__find_program_by_name(skel->obj, curr_name);

		if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name"))

			goto cleanup;



		bpf_program__set_autoload(prog, !strcmp(curr_name, prog_name));

	}



	err = task_kfunc_failure__load(skel);

	if (!ASSERT_ERR(err, "unexpected load success"))

		goto cleanup;



	if (!ASSERT_OK_PTR(strstr(obj_log_buf, expected_err_msg), "expected_err_msg")) {

		fprintf(stderr, "Expected err_msg: %s\n", expected_err_msg);

		fprintf(stderr, "Verifier output: %s\n", obj_log_buf);

	}



cleanup:

	task_kfunc_failure__destroy(skel);

}



void test_task_kfunc(void)

{

	int i;



	for (i = 0; i < ARRAY_SIZE(success_tests); i++) {

		if (!test__start_subtest(success_tests[i]))

			continue;



		run_success_test(success_tests[i]);

	}



	for (i = 0; i < ARRAY_SIZE(failure_tests); i++) {

		if (!test__start_subtest(failure_tests[i].prog_name))

			continue;



		verify_fail(failure_tests[i].prog_name, failure_tests[i].expected_err_msg);

	}

}

tools/testing/selftests/bpf/progs/task_kfunc_common.h

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Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */



#ifndef _TASK_KFUNC_COMMON_H

#define _TASK_KFUNC_COMMON_H



#include <errno.h>

#include <vmlinux.h>

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>



struct __tasks_kfunc_map_value {

	struct task_struct __kptr_ref * task;

};



struct hash_map {

	__uint(type, BPF_MAP_TYPE_HASH);

	__type(key, int);

	__type(value, struct __tasks_kfunc_map_value);

	__uint(max_entries, 1);

} __tasks_kfunc_map SEC(".maps");



struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym;

struct task_struct *bpf_task_kptr_get(struct task_struct **pp) __ksym;

void bpf_task_release(struct task_struct *p) __ksym;



static inline struct __tasks_kfunc_map_value *tasks_kfunc_map_value_lookup(struct task_struct *p)

{

	s32 pid;

	long status;



	status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid);

	if (status)

		return NULL;



	return bpf_map_lookup_elem(&__tasks_kfunc_map, &pid);

}



static inline int tasks_kfunc_map_insert(struct task_struct *p)

{

	struct __tasks_kfunc_map_value local, *v;

	long status;

	struct task_struct *acquired, *old;

	s32 pid;



	status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid);

	if (status)

		return status;



	local.task = NULL;

	status = bpf_map_update_elem(&__tasks_kfunc_map, &pid, &local, BPF_NOEXIST);

	if (status)

		return status;



	v = bpf_map_lookup_elem(&__tasks_kfunc_map, &pid);

	if (!v) {

		bpf_map_delete_elem(&__tasks_kfunc_map, &pid);

		return -ENOENT;

	}



	acquired = bpf_task_acquire(p);

	old = bpf_kptr_xchg(&v->task, acquired);

	if (old) {

		bpf_task_release(old);

		return -EEXIST;

	}



	return 0;

}



#endif /* _TASK_KFUNC_COMMON_H */

tools/testing/selftests/bpf/progs/task_kfunc_failure.c

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+260 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */



#include <vmlinux.h>

#include <bpf/bpf_tracing.h>

#include <bpf/bpf_helpers.h>



#include "task_kfunc_common.h"



char _license[] SEC("license") = "GPL";



/* Prototype for all of the program trace events below:

 *

 * TRACE_EVENT(task_newtask,

 *         TP_PROTO(struct task_struct *p, u64 clone_flags)

 */



static struct __tasks_kfunc_map_value *insert_lookup_task(struct task_struct *task)

{

	int status;



	status = tasks_kfunc_map_insert(task);

	if (status)

		return NULL;



	return tasks_kfunc_map_value_lookup(task);

}



SEC("tp_btf/task_newtask")

int BPF_PROG(task_kfunc_acquire_untrusted, struct task_struct *task, u64 clone_flags)

{

	struct task_struct *acquired;

	struct __tasks_kfunc_map_value *v;



	v = insert_lookup_task(task);

	if (!v)

		return 0;



	/* Can't invoke bpf_task_acquire() on an untrusted pointer. */

	acquired = bpf_task_acquire(v->task);

	bpf_task_release(acquired);



	return 0;

}



SEC("tp_btf/task_newtask")

int BPF_PROG(task_kfunc_acquire_fp, struct task_struct *task, u64 clone_flags)

{

	struct task_struct *acquired, *stack_task = (struct task_struct *)&clone_flags;



	/* Can't invoke bpf_task_acquire() on a random frame pointer. */

	acquired = bpf_task_acquire((struct task_struct *)&stack_task);

	bpf_task_release(acquired);



	return 0;

}



SEC("kretprobe/free_task")

int BPF_PROG(task_kfunc_acquire_unsafe_kretprobe, struct task_struct *task, u64 clone_flags)

{

	struct task_struct *acquired;



	acquired = bpf_task_acquire(task);

	/* Can't release a bpf_task_acquire()'d task without a NULL check. */

	bpf_task_release(acquired);



	return 0;

}



SEC("tp_btf/task_newtask")

int BPF_PROG(task_kfunc_acquire_trusted_walked, struct task_struct *task, u64 clone_flags)

{

	struct task_struct *acquired;



	/* Can't invoke bpf_task_acquire() on a trusted pointer obtained from walking a struct. */

	acquired = bpf_task_acquire(task->last_wakee);

	bpf_task_release(acquired);



	return 0;

}





SEC("tp_btf/task_newtask")

int BPF_PROG(task_kfunc_acquire_null, struct task_struct *task, u64 clone_flags)

{

	struct task_struct *acquired;



	/* Can't invoke bpf_task_acquire() on a NULL pointer. */

	acquired = bpf_task_acquire(NULL);

	if (!acquired)

		return 0;

	bpf_task_release(acquired);



	return 0;

}



SEC("tp_btf/task_newtask")

int BPF_PROG(task_kfunc_acquire_unreleased, struct task_struct *task, u64 clone_flags)

{

	struct task_struct *acquired;



	acquired = bpf_task_acquire(task);



	/* Acquired task is never released. */



	return 0;

}



SEC("tp_btf/task_newtask")

int BPF_PROG(task_kfunc_get_non_kptr_param, struct task_struct *task, u64 clone_flags)

{

	struct task_struct *kptr;



	/* Cannot use bpf_task_kptr_get() on a non-kptr, even on a valid task. */

	kptr = bpf_task_kptr_get(&task);

	if (!kptr)

		return 0;



	bpf_task_release(kptr);



	return 0;

}



SEC("tp_btf/task_newtask")

int BPF_PROG(task_kfunc_get_non_kptr_acquired, struct task_struct *task, u64 clone_flags)

{

	struct task_struct *kptr, *acquired;



	acquired = bpf_task_acquire(task);



	/* Cannot use bpf_task_kptr_get() on a non-kptr, even if it was acquired. */

	kptr = bpf_task_kptr_get(&acquired);

	bpf_task_release(acquired);

	if (!kptr)

		return 0;



	bpf_task_release(kptr);



	return 0;

}



SEC("tp_btf/task_newtask")

int BPF_PROG(task_kfunc_get_null, struct task_struct *task, u64 clone_flags)

{

	struct task_struct *kptr;



	/* Cannot use bpf_task_kptr_get() on a NULL pointer. */

	kptr = bpf_task_kptr_get(NULL);

	if (!kptr)

		return 0;



	bpf_task_release(kptr);



	return 0;

}



SEC("tp_btf/task_newtask")

int BPF_PROG(task_kfunc_xchg_unreleased, struct task_struct *task, u64 clone_flags)

{

	struct task_struct *kptr;

	struct __tasks_kfunc_map_value *v;



	v = insert_lookup_task(task);

	if (!v)

		return 0;



	kptr = bpf_kptr_xchg(&v->task, NULL);

	if (!kptr)

		return 0;



	/* Kptr retrieved from map is never released. */



	return 0;

}



SEC("tp_btf/task_newtask")

int BPF_PROG(task_kfunc_get_unreleased, struct task_struct *task, u64 clone_flags)

{

	struct task_struct *kptr;

	struct __tasks_kfunc_map_value *v;



	v = insert_lookup_task(task);

	if (!v)

		return 0;



	kptr = bpf_task_kptr_get(&v->task);

	if (!kptr)

		return 0;



	/* Kptr acquired above is never released. */



	return 0;

}



SEC("tp_btf/task_newtask")

int BPF_PROG(task_kfunc_release_untrusted, struct task_struct *task, u64 clone_flags)

{

	struct __tasks_kfunc_map_value *v;



	v = insert_lookup_task(task);

	if (!v)

		return 0;



	/* Can't invoke bpf_task_release() on an untrusted pointer. */

	bpf_task_release(v->task);



	return 0;

}



SEC("tp_btf/task_newtask")

int BPF_PROG(task_kfunc_release_fp, struct task_struct *task, u64 clone_flags)

{

	struct task_struct *acquired = (struct task_struct *)&clone_flags;



	/* Cannot release random frame pointer. */

	bpf_task_release(acquired);



	return 0;

}



SEC("tp_btf/task_newtask")

int BPF_PROG(task_kfunc_release_null, struct task_struct *task, u64 clone_flags)

{

	struct __tasks_kfunc_map_value local, *v;

	long status;

	struct task_struct *acquired, *old;

	s32 pid;



	status = bpf_probe_read_kernel(&pid, sizeof(pid), &task->pid);

	if (status)

		return 0;



	local.task = NULL;

	status = bpf_map_update_elem(&__tasks_kfunc_map, &pid, &local, BPF_NOEXIST);

	if (status)

		return status;



	v = bpf_map_lookup_elem(&__tasks_kfunc_map, &pid);

	if (!v)

		return -ENOENT;



	acquired = bpf_task_acquire(task);



	old = bpf_kptr_xchg(&v->task, acquired);



	/* old cannot be passed to bpf_task_release() without a NULL check. */

	bpf_task_release(old);

	bpf_task_release(old);



	return 0;

}



SEC("tp_btf/task_newtask")

int BPF_PROG(task_kfunc_release_unacquired, struct task_struct *task, u64 clone_flags)

{

	/* Cannot release trusted task pointer which was not acquired. */

	bpf_task_release(task);



	return 0;

}

tools/testing/selftests/bpf/progs/task_kfunc_success.c

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+149 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */



#include <vmlinux.h>

#include <bpf/bpf_tracing.h>

#include <bpf/bpf_helpers.h>



#include "task_kfunc_common.h"



char _license[] SEC("license") = "GPL";



int err, pid;



/* Prototype for all of the program trace events below:

 *

 * TRACE_EVENT(task_newtask,

 *         TP_PROTO(struct task_struct *p, u64 clone_flags)

 */



static bool is_test_kfunc_task(void)

{

	int cur_pid = bpf_get_current_pid_tgid() >> 32;



	return pid == cur_pid;

}



static int test_acquire_release(struct task_struct *task)

{

	struct task_struct *acquired;



	acquired = bpf_task_acquire(task);

	bpf_task_release(acquired);



	return 0;

}



SEC("tp_btf/task_newtask")

int BPF_PROG(test_task_acquire_release_argument, struct task_struct *task, u64 clone_flags)

{

	if (!is_test_kfunc_task())

		return 0;



	return test_acquire_release(task);

}



SEC("tp_btf/task_newtask")

int BPF_PROG(test_task_acquire_release_current, struct task_struct *task, u64 clone_flags)

{

	if (!is_test_kfunc_task())

		return 0;



	return test_acquire_release(bpf_get_current_task_btf());

}



SEC("tp_btf/task_newtask")

int BPF_PROG(test_task_acquire_leave_in_map, struct task_struct *task, u64 clone_flags)

{

	long status;



	if (!is_test_kfunc_task())

		return 0;



	status = tasks_kfunc_map_insert(task);

	if (status)

		err = 1;



	return 0;

}



SEC("tp_btf/task_newtask")

int BPF_PROG(test_task_xchg_release, struct task_struct *task, u64 clone_flags)

{

	struct task_struct *kptr;

	struct __tasks_kfunc_map_value *v;

	long status;



	if (!is_test_kfunc_task())

		return 0;



	status = tasks_kfunc_map_insert(task);

	if (status) {

		err = 1;

		return 0;

	}



	v = tasks_kfunc_map_value_lookup(task);

	if (!v) {

		err = 2;

		return 0;

	}



	kptr = bpf_kptr_xchg(&v->task, NULL);

	if (!kptr) {

		err = 3;

		return 0;

	}



	bpf_task_release(kptr);



	return 0;

}



SEC("tp_btf/task_newtask")

int BPF_PROG(test_task_get_release, struct task_struct *task, u64 clone_flags)

{

	struct task_struct *kptr;

	struct __tasks_kfunc_map_value *v;

	long status;



	if (!is_test_kfunc_task())

		return 0;



	status = tasks_kfunc_map_insert(task);

	if (status) {

		err = 1;

		return 0;

	}



	v = tasks_kfunc_map_value_lookup(task);

	if (!v) {

		err = 2;

		return 0;

	}



	kptr = bpf_task_kptr_get(&v->task);

	if (!kptr) {

		err = 3;

		return 0;

	}



	bpf_task_release(kptr);



	return 0;

}



SEC("tp_btf/task_newtask")

int BPF_PROG(test_task_current_acquire_release, struct task_struct *task, u64 clone_flags)

{

	struct task_struct *current, *acquired;



	if (!is_test_kfunc_task())

		return 0;



	current = bpf_get_current_task_btf();

	acquired = bpf_task_acquire(current);

	bpf_task_release(acquired);



	return 0;

}