Commit f583ddf1 authored by David Vernet's avatar David Vernet Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add cgroup kfunc / kptr selftests 



This patch adds a selftest suite to validate the cgroup kfuncs that were
added in the prior patch.

Signed-off-by: default avatarDavid Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20221122055458.173143-3-void@manifault.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent fda01efc

tools/testing/selftests/bpf/DENYLIST.s390x

+1 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ bpf_nf # JIT does not support calling kernel f 
bpf_tcp_ca                               # JIT does not support calling kernel function                                (kfunc)

cb_refs                                  # expected error message unexpected error: -524                               (trampoline)

cgroup_hierarchical_stats                # JIT does not support calling kernel function                                (kfunc)

cgrp_kfunc                               # JIT does not support calling kernel function

cgrp_local_storage                       # prog_attach unexpected error: -524                                          (trampoline)

core_read_macros                         # unknown func bpf_probe_read#4                                               (overlapping)

d_path                                   # failed to auto-attach program 'prog_stat': -524                             (trampoline)

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

0 → 100644
+174 −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 <cgroup_helpers.h>

#include <test_progs.h>



#include "cgrp_kfunc_failure.skel.h"

#include "cgrp_kfunc_success.skel.h"



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

static char obj_log_buf[1048576];



static struct cgrp_kfunc_success *open_load_cgrp_kfunc_skel(void)

{

	struct cgrp_kfunc_success *skel;

	int err;



	skel = cgrp_kfunc_success__open();

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

		return NULL;



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



	err = cgrp_kfunc_success__load(skel);

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

		goto cleanup;



	return skel;



cleanup:

	cgrp_kfunc_success__destroy(skel);

	return NULL;

}



static int mkdir_rm_test_dir(void)

{

	int fd;

	const char *cgrp_path = "cgrp_kfunc";



	fd = create_and_get_cgroup(cgrp_path);

	if (!ASSERT_GT(fd, 0, "mkdir_cgrp_fd"))

		return -1;



	close(fd);

	remove_cgroup(cgrp_path);



	return 0;

}



static void run_success_test(const char *prog_name)

{

	struct cgrp_kfunc_success *skel;

	struct bpf_program *prog;

	struct bpf_link *link = NULL;



	skel = open_load_cgrp_kfunc_skel();

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

		return;



	if (!ASSERT_OK(skel->bss->err, "pre_mkdir_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;



	ASSERT_EQ(skel->bss->invocations, 0, "pre_rmdir_count");

	if (!ASSERT_OK(mkdir_rm_test_dir(), "cgrp_mkdir"))

		goto cleanup;



	ASSERT_EQ(skel->bss->invocations, 1, "post_rmdir_count");

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



cleanup:

	bpf_link__destroy(link);

	cgrp_kfunc_success__destroy(skel);

}



static const char * const success_tests[] = {

	"test_cgrp_acquire_release_argument",

	"test_cgrp_acquire_leave_in_map",

	"test_cgrp_xchg_release",

	"test_cgrp_get_release",

};



static struct {

	const char *prog_name;

	const char *expected_err_msg;

} failure_tests[] = {

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

	{"cgrp_kfunc_acquire_fp", "arg#0 pointer type STRUCT cgroup must point"},

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

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

	{"cgrp_kfunc_acquire_null", "arg#0 pointer type STRUCT cgroup must point"},

	{"cgrp_kfunc_acquire_unreleased", "Unreleased reference"},

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

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

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

	{"cgrp_kfunc_xchg_unreleased", "Unreleased reference"},

	{"cgrp_kfunc_get_unreleased", "Unreleased reference"},

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

	{"cgrp_kfunc_release_fp", "arg#0 pointer type STRUCT cgroup must point"},

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

	{"cgrp_kfunc_release_unacquired", "release kernel function bpf_cgroup_release expects"},

};



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

{

	LIBBPF_OPTS(bpf_object_open_opts, opts);

	struct cgrp_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 = cgrp_kfunc_failure__open_opts(&opts);

	if (!ASSERT_OK_PTR(skel, "cgrp_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 = cgrp_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:

	cgrp_kfunc_failure__destroy(skel);

}



void test_cgrp_kfunc(void)

{

	int i, err;



	err = setup_cgroup_environment();

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

		goto cleanup;



	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);

	}



cleanup:

	cleanup_cgroup_environment();

}

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

0 → 100644
+71 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

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



#ifndef _CGRP_KFUNC_COMMON_H

#define _CGRP_KFUNC_COMMON_H



#include <errno.h>

#include <vmlinux.h>

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>



struct __cgrps_kfunc_map_value {

	struct cgroup __kptr_ref * cgrp;

};



struct hash_map {

	__uint(type, BPF_MAP_TYPE_HASH);

	__type(key, int);

	__type(value, struct __cgrps_kfunc_map_value);

	__uint(max_entries, 1);

} __cgrps_kfunc_map SEC(".maps");



struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym;

struct cgroup *bpf_cgroup_kptr_get(struct cgroup **pp) __ksym;

void bpf_cgroup_release(struct cgroup *p) __ksym;



static inline struct __cgrps_kfunc_map_value *cgrps_kfunc_map_value_lookup(struct cgroup *cgrp)

{

	s32 id;

	long status;



	status = bpf_probe_read_kernel(&id, sizeof(id), &cgrp->self.id);

	if (status)

		return NULL;



	return bpf_map_lookup_elem(&__cgrps_kfunc_map, &id);

}



static inline int cgrps_kfunc_map_insert(struct cgroup *cgrp)

{

	struct __cgrps_kfunc_map_value local, *v;

	long status;

	struct cgroup *acquired, *old;

	s32 id;



	status = bpf_probe_read_kernel(&id, sizeof(id), &cgrp->self.id);

	if (status)

		return status;



	local.cgrp = NULL;

	status = bpf_map_update_elem(&__cgrps_kfunc_map, &id, &local, BPF_NOEXIST);

	if (status)

		return status;



	v = bpf_map_lookup_elem(&__cgrps_kfunc_map, &id);

	if (!v) {

		bpf_map_delete_elem(&__cgrps_kfunc_map, &id);

		return -ENOENT;

	}



	acquired = bpf_cgroup_acquire(cgrp);

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

	if (old) {

		bpf_cgroup_release(old);

		return -EEXIST;

	}



	return 0;

}



#endif /* _CGRP_KFUNC_COMMON_H */

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

0 → 100644
+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 "cgrp_kfunc_common.h"



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



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

 *

 * TRACE_EVENT(cgroup_mkdir,

 *         TP_PROTO(struct cgroup *cgrp, const char *path),

 *         TP_ARGS(cgrp, path)

 */



static struct __cgrps_kfunc_map_value *insert_lookup_cgrp(struct cgroup *cgrp)

{

	int status;



	status = cgrps_kfunc_map_insert(cgrp);

	if (status)

		return NULL;



	return cgrps_kfunc_map_value_lookup(cgrp);

}



SEC("tp_btf/cgroup_mkdir")

int BPF_PROG(cgrp_kfunc_acquire_untrusted, struct cgroup *cgrp, const char *path)

{

	struct cgroup *acquired;

	struct __cgrps_kfunc_map_value *v;



	v = insert_lookup_cgrp(cgrp);

	if (!v)

		return 0;



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

	acquired = bpf_cgroup_acquire(v->cgrp);

	bpf_cgroup_release(acquired);



	return 0;

}



SEC("tp_btf/cgroup_mkdir")

int BPF_PROG(cgrp_kfunc_acquire_fp, struct cgroup *cgrp, const char *path)

{

	struct cgroup *acquired, *stack_cgrp = (struct cgroup *)&path;



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

	acquired = bpf_cgroup_acquire((struct cgroup *)&stack_cgrp);

	bpf_cgroup_release(acquired);



	return 0;

}



SEC("kretprobe/cgroup_destroy_locked")

int BPF_PROG(cgrp_kfunc_acquire_unsafe_kretprobe, struct cgroup *cgrp)

{

	struct cgroup *acquired;



	/* Can't acquire an untrusted struct cgroup * pointer. */

	acquired = bpf_cgroup_acquire(cgrp);

	bpf_cgroup_release(acquired);



	return 0;

}



SEC("tp_btf/cgroup_mkdir")

int BPF_PROG(cgrp_kfunc_acquire_trusted_walked, struct cgroup *cgrp, const char *path)

{

	struct cgroup *acquired;



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

	acquired = bpf_cgroup_acquire(cgrp->old_dom_cgrp);

	bpf_cgroup_release(acquired);



	return 0;

}





SEC("tp_btf/cgroup_mkdir")

int BPF_PROG(cgrp_kfunc_acquire_null, struct cgroup *cgrp, const char *path)

{

	struct cgroup *acquired;



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

	acquired = bpf_cgroup_acquire(NULL);

	if (!acquired)

		return 0;

	bpf_cgroup_release(acquired);



	return 0;

}



SEC("tp_btf/cgroup_mkdir")

int BPF_PROG(cgrp_kfunc_acquire_unreleased, struct cgroup *cgrp, const char *path)

{

	struct cgroup *acquired;



	acquired = bpf_cgroup_acquire(cgrp);



	/* Acquired cgroup is never released. */



	return 0;

}



SEC("tp_btf/cgroup_mkdir")

int BPF_PROG(cgrp_kfunc_get_non_kptr_param, struct cgroup *cgrp, const char *path)

{

	struct cgroup *kptr;



	/* Cannot use bpf_cgroup_kptr_get() on a non-kptr, even on a valid cgroup. */

	kptr = bpf_cgroup_kptr_get(&cgrp);

	if (!kptr)

		return 0;



	bpf_cgroup_release(kptr);



	return 0;

}



SEC("tp_btf/cgroup_mkdir")

int BPF_PROG(cgrp_kfunc_get_non_kptr_acquired, struct cgroup *cgrp, const char *path)

{

	struct cgroup *kptr, *acquired;



	acquired = bpf_cgroup_acquire(cgrp);



	/* Cannot use bpf_cgroup_kptr_get() on a non-map-value, even if the kptr was acquired. */

	kptr = bpf_cgroup_kptr_get(&acquired);

	bpf_cgroup_release(acquired);

	if (!kptr)

		return 0;



	bpf_cgroup_release(kptr);



	return 0;

}



SEC("tp_btf/cgroup_mkdir")

int BPF_PROG(cgrp_kfunc_get_null, struct cgroup *cgrp, const char *path)

{

	struct cgroup *kptr;



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

	kptr = bpf_cgroup_kptr_get(NULL);

	if (!kptr)

		return 0;



	bpf_cgroup_release(kptr);



	return 0;

}



SEC("tp_btf/cgroup_mkdir")

int BPF_PROG(cgrp_kfunc_xchg_unreleased, struct cgroup *cgrp, const char *path)

{

	struct cgroup *kptr;

	struct __cgrps_kfunc_map_value *v;



	v = insert_lookup_cgrp(cgrp);

	if (!v)

		return 0;



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

	if (!kptr)

		return 0;



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



	return 0;

}



SEC("tp_btf/cgroup_mkdir")

int BPF_PROG(cgrp_kfunc_get_unreleased, struct cgroup *cgrp, const char *path)

{

	struct cgroup *kptr;

	struct __cgrps_kfunc_map_value *v;



	v = insert_lookup_cgrp(cgrp);

	if (!v)

		return 0;



	kptr = bpf_cgroup_kptr_get(&v->cgrp);

	if (!kptr)

		return 0;



	/* Kptr acquired above is never released. */



	return 0;

}



SEC("tp_btf/cgroup_mkdir")

int BPF_PROG(cgrp_kfunc_release_untrusted, struct cgroup *cgrp, const char *path)

{

	struct __cgrps_kfunc_map_value *v;



	v = insert_lookup_cgrp(cgrp);

	if (!v)

		return 0;



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

	bpf_cgroup_release(v->cgrp);



	return 0;

}



SEC("tp_btf/cgroup_mkdir")

int BPF_PROG(cgrp_kfunc_release_fp, struct cgroup *cgrp, const char *path)

{

	struct cgroup *acquired = (struct cgroup *)&path;



	/* Cannot release random frame pointer. */

	bpf_cgroup_release(acquired);



	return 0;

}



SEC("tp_btf/cgroup_mkdir")

int BPF_PROG(cgrp_kfunc_release_null, struct cgroup *cgrp, const char *path)

{

	struct __cgrps_kfunc_map_value local, *v;

	long status;

	struct cgroup *acquired, *old;

	s32 id;



	status = bpf_probe_read_kernel(&id, sizeof(id), &cgrp->self.id);

	if (status)

		return 0;



	local.cgrp = NULL;

	status = bpf_map_update_elem(&__cgrps_kfunc_map, &id, &local, BPF_NOEXIST);

	if (status)

		return status;



	v = bpf_map_lookup_elem(&__cgrps_kfunc_map, &id);

	if (!v)

		return -ENOENT;



	acquired = bpf_cgroup_acquire(cgrp);



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



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

	bpf_cgroup_release(old);



	return 0;

}



SEC("tp_btf/cgroup_mkdir")

int BPF_PROG(cgrp_kfunc_release_unacquired, struct cgroup *cgrp, const char *path)

{

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

	bpf_cgroup_release(cgrp);



	return 0;

}

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

0 → 100644
+125 −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 "cgrp_kfunc_common.h"



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



int err, pid, invocations;



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

 *

 * TRACE_EVENT(cgroup_mkdir,

 *         TP_PROTO(struct cgroup *cgrp, const char *path),

 *         TP_ARGS(cgrp, path)

 */



static bool is_test_kfunc_task(void)

{

	int cur_pid = bpf_get_current_pid_tgid() >> 32;

	bool same = pid == cur_pid;



	if (same)

		__sync_fetch_and_add(&invocations, 1);



	return same;

}



SEC("tp_btf/cgroup_mkdir")

int BPF_PROG(test_cgrp_acquire_release_argument, struct cgroup *cgrp, const char *path)

{

	struct cgroup *acquired;



	if (!is_test_kfunc_task())

		return 0;



	acquired = bpf_cgroup_acquire(cgrp);

	bpf_cgroup_release(acquired);



	return 0;

}



SEC("tp_btf/cgroup_mkdir")

int BPF_PROG(test_cgrp_acquire_leave_in_map, struct cgroup *cgrp, const char *path)

{

	long status;



	if (!is_test_kfunc_task())

		return 0;



	status = cgrps_kfunc_map_insert(cgrp);

	if (status)

		err = 1;



	return 0;

}



SEC("tp_btf/cgroup_mkdir")

int BPF_PROG(test_cgrp_xchg_release, struct cgroup *cgrp, const char *path)

{

	struct cgroup *kptr;

	struct __cgrps_kfunc_map_value *v;

	long status;



	if (!is_test_kfunc_task())

		return 0;



	status = cgrps_kfunc_map_insert(cgrp);

	if (status) {

		err = 1;

		return 0;

	}



	v = cgrps_kfunc_map_value_lookup(cgrp);

	if (!v) {

		err = 2;

		return 0;

	}



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

	if (!kptr) {

		err = 3;

		return 0;

	}



	bpf_cgroup_release(kptr);



	return 0;

}



SEC("tp_btf/cgroup_mkdir")

int BPF_PROG(test_cgrp_get_release, struct cgroup *cgrp, const char *path)

{

	struct cgroup *kptr;

	struct __cgrps_kfunc_map_value *v;

	long status;



	if (!is_test_kfunc_task())

		return 0;



	status = cgrps_kfunc_map_insert(cgrp);

	if (status) {

		err = 1;

		return 0;

	}



	v = cgrps_kfunc_map_value_lookup(cgrp);

	if (!v) {

		err = 2;

		return 0;

	}



	kptr = bpf_cgroup_kptr_get(&v->cgrp);

	if (!kptr) {

		err = 3;

		return 0;

	}



	bpf_cgroup_release(kptr);



	return 0;

}