Commit fe0dd9d4 authored by Hao Luo's avatar Hao Luo Committed by Alexei Starovoitov
Browse files

selftests/bpf: Test cgroup_iter. 



Add a selftest for cgroup_iter. The selftest creates a mini cgroup tree
of the following structure:

    ROOT (working cgroup)
     |
   PARENT
  /      \
CHILD1  CHILD2

and tests the following scenarios:

 - invalid cgroup fd.
 - pre-order walk over descendants from PARENT.
 - post-order walk over descendants from PARENT.
 - walk of ancestors from PARENT.
 - process only a single object (i.e. PARENT).
 - early termination.

Acked-by: default avatarYonghong Song <yhs@fb.com>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarHao Luo <haoluo@google.com>
Link: https://lore.kernel.org/r/20220824233117.1312810-3-haoluo@google.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent d4ccaf58

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

+1 −1
Original line number Diff line number Diff line
@@ -764,7 +764,7 @@ static void test_btf_dump_struct_data(struct btf *btf, struct btf_dump *d, 


	/* union with nested struct */

	TEST_BTF_DUMP_DATA(btf, d, "union", str, union bpf_iter_link_info, BTF_F_COMPACT,

			   "(union bpf_iter_link_info){.map = (struct){.map_fd = (__u32)1,},.cgroup = (struct){.order = (__u32)1,.cgroup_fd = (__u32)1,},}",

			   "(union bpf_iter_link_info){.map = (struct){.map_fd = (__u32)1,},.cgroup = (struct){.order = (enum bpf_cgroup_iter_order)BPF_ITER_SELF_ONLY,.cgroup_fd = (__u32)1,},}",

			   { .cgroup = { .order = 1, .cgroup_fd = 1, }});



	/* struct skb with nested structs/unions; because type output is so

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

0 → 100644
+224 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2022 Google */



#include <test_progs.h>

#include <bpf/libbpf.h>

#include <bpf/btf.h>

#include "cgroup_iter.skel.h"

#include "cgroup_helpers.h"



#define ROOT           0

#define PARENT         1

#define CHILD1         2

#define CHILD2         3

#define NUM_CGROUPS    4



#define PROLOGUE       "prologue\n"

#define EPILOGUE       "epilogue\n"



static const char *cg_path[] = {

	"/", "/parent", "/parent/child1", "/parent/child2"

};



static int cg_fd[] = {-1, -1, -1, -1};

static unsigned long long cg_id[] = {0, 0, 0, 0};

static char expected_output[64];



static int setup_cgroups(void)

{

	int fd, i = 0;



	for (i = 0; i < NUM_CGROUPS; i++) {

		fd = create_and_get_cgroup(cg_path[i]);

		if (fd < 0)

			return fd;



		cg_fd[i] = fd;

		cg_id[i] = get_cgroup_id(cg_path[i]);

	}

	return 0;

}



static void cleanup_cgroups(void)

{

	int i;



	for (i = 0; i < NUM_CGROUPS; i++)

		close(cg_fd[i]);

}



static void read_from_cgroup_iter(struct bpf_program *prog, int cgroup_fd,

				  int order, const char *testname)

{

	DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts);

	union bpf_iter_link_info linfo;

	struct bpf_link *link;

	int len, iter_fd;

	static char buf[128];

	size_t left;

	char *p;



	memset(&linfo, 0, sizeof(linfo));

	linfo.cgroup.cgroup_fd = cgroup_fd;

	linfo.cgroup.order = order;

	opts.link_info = &linfo;

	opts.link_info_len = sizeof(linfo);



	link = bpf_program__attach_iter(prog, &opts);

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

		return;



	iter_fd = bpf_iter_create(bpf_link__fd(link));

	if (iter_fd < 0)

		goto free_link;



	memset(buf, 0, sizeof(buf));

	left = ARRAY_SIZE(buf);

	p = buf;

	while ((len = read(iter_fd, p, left)) > 0) {

		p += len;

		left -= len;

	}



	ASSERT_STREQ(buf, expected_output, testname);



	/* read() after iter finishes should be ok. */

	if (len == 0)

		ASSERT_OK(read(iter_fd, buf, sizeof(buf)), "second_read");



	close(iter_fd);

free_link:

	bpf_link__destroy(link);

}



/* Invalid cgroup. */

static void test_invalid_cgroup(struct cgroup_iter *skel)

{

	DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts);

	union bpf_iter_link_info linfo;

	struct bpf_link *link;



	memset(&linfo, 0, sizeof(linfo));

	linfo.cgroup.cgroup_fd = (__u32)-1;

	opts.link_info = &linfo;

	opts.link_info_len = sizeof(linfo);



	link = bpf_program__attach_iter(skel->progs.cgroup_id_printer, &opts);

	ASSERT_ERR_PTR(link, "attach_iter");

	bpf_link__destroy(link);

}



/* Specifying both cgroup_fd and cgroup_id is invalid. */

static void test_invalid_cgroup_spec(struct cgroup_iter *skel)

{

	DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts);

	union bpf_iter_link_info linfo;

	struct bpf_link *link;



	memset(&linfo, 0, sizeof(linfo));

	linfo.cgroup.cgroup_fd = (__u32)cg_fd[PARENT];

	linfo.cgroup.cgroup_id = (__u64)cg_id[PARENT];

	opts.link_info = &linfo;

	opts.link_info_len = sizeof(linfo);



	link = bpf_program__attach_iter(skel->progs.cgroup_id_printer, &opts);

	ASSERT_ERR_PTR(link, "attach_iter");

	bpf_link__destroy(link);

}



/* Preorder walk prints parent and child in order. */

static void test_walk_preorder(struct cgroup_iter *skel)

{

	snprintf(expected_output, sizeof(expected_output),

		 PROLOGUE "%8llu\n%8llu\n%8llu\n" EPILOGUE,

		 cg_id[PARENT], cg_id[CHILD1], cg_id[CHILD2]);



	read_from_cgroup_iter(skel->progs.cgroup_id_printer, cg_fd[PARENT],

			      BPF_ITER_DESCENDANTS_PRE, "preorder");

}



/* Postorder walk prints child and parent in order. */

static void test_walk_postorder(struct cgroup_iter *skel)

{

	snprintf(expected_output, sizeof(expected_output),

		 PROLOGUE "%8llu\n%8llu\n%8llu\n" EPILOGUE,

		 cg_id[CHILD1], cg_id[CHILD2], cg_id[PARENT]);



	read_from_cgroup_iter(skel->progs.cgroup_id_printer, cg_fd[PARENT],

			      BPF_ITER_DESCENDANTS_POST, "postorder");

}



/* Walking parents prints parent and then root. */

static void test_walk_ancestors_up(struct cgroup_iter *skel)

{

	/* terminate the walk when ROOT is met. */

	skel->bss->terminal_cgroup = cg_id[ROOT];



	snprintf(expected_output, sizeof(expected_output),

		 PROLOGUE "%8llu\n%8llu\n" EPILOGUE,

		 cg_id[PARENT], cg_id[ROOT]);



	read_from_cgroup_iter(skel->progs.cgroup_id_printer, cg_fd[PARENT],

			      BPF_ITER_ANCESTORS_UP, "ancestors_up");



	skel->bss->terminal_cgroup = 0;

}



/* Early termination prints parent only. */

static void test_early_termination(struct cgroup_iter *skel)

{

	/* terminate the walk after the first element is processed. */

	skel->bss->terminate_early = 1;



	snprintf(expected_output, sizeof(expected_output),

		 PROLOGUE "%8llu\n" EPILOGUE, cg_id[PARENT]);



	read_from_cgroup_iter(skel->progs.cgroup_id_printer, cg_fd[PARENT],

			      BPF_ITER_DESCENDANTS_PRE, "early_termination");



	skel->bss->terminate_early = 0;

}



/* Waling self prints self only. */

static void test_walk_self_only(struct cgroup_iter *skel)

{

	snprintf(expected_output, sizeof(expected_output),

		 PROLOGUE "%8llu\n" EPILOGUE, cg_id[PARENT]);



	read_from_cgroup_iter(skel->progs.cgroup_id_printer, cg_fd[PARENT],

			      BPF_ITER_SELF_ONLY, "self_only");

}



void test_cgroup_iter(void)

{

	struct cgroup_iter *skel = NULL;



	if (setup_cgroup_environment())

		return;



	if (setup_cgroups())

		goto out;



	skel = cgroup_iter__open_and_load();

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

		goto out;



	if (test__start_subtest("cgroup_iter__invalid_cgroup"))

		test_invalid_cgroup(skel);

	if (test__start_subtest("cgroup_iter__invalid_cgroup_spec"))

		test_invalid_cgroup_spec(skel);

	if (test__start_subtest("cgroup_iter__preorder"))

		test_walk_preorder(skel);

	if (test__start_subtest("cgroup_iter__postorder"))

		test_walk_postorder(skel);

	if (test__start_subtest("cgroup_iter__ancestors_up_walk"))

		test_walk_ancestors_up(skel);

	if (test__start_subtest("cgroup_iter__early_termination"))

		test_early_termination(skel);

	if (test__start_subtest("cgroup_iter__self_only"))

		test_walk_self_only(skel);

out:

	cgroup_iter__destroy(skel);

	cleanup_cgroups();

	cleanup_cgroup_environment();

}

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

+7 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#define bpf_iter__bpf_sk_storage_map bpf_iter__bpf_sk_storage_map___not_used

#define bpf_iter__sockmap bpf_iter__sockmap___not_used

#define bpf_iter__bpf_link bpf_iter__bpf_link___not_used

#define bpf_iter__cgroup bpf_iter__cgroup___not_used

#define btf_ptr btf_ptr___not_used

#define BTF_F_COMPACT BTF_F_COMPACT___not_used

#define BTF_F_NONAME BTF_F_NONAME___not_used
@@ -40,6 +41,7 @@ 
#undef bpf_iter__bpf_sk_storage_map

#undef bpf_iter__sockmap

#undef bpf_iter__bpf_link

#undef bpf_iter__cgroup

#undef btf_ptr

#undef BTF_F_COMPACT

#undef BTF_F_NONAME
@@ -141,6 +143,11 @@ struct bpf_iter__bpf_link { 
	struct bpf_link *link;

};



struct bpf_iter__cgroup {

	struct bpf_iter_meta *meta;

	struct cgroup *cgroup;

} __attribute__((preserve_access_index));



struct btf_ptr {

	void *ptr;

	__u32 type_id;

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

0 → 100644
+39 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2022 Google */



#include "bpf_iter.h"

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>



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

int terminate_early = 0;

u64 terminal_cgroup = 0;



static inline u64 cgroup_id(struct cgroup *cgrp)

{

	return cgrp->kn->id;

}



SEC("iter/cgroup")

int cgroup_id_printer(struct bpf_iter__cgroup *ctx)

{

	struct seq_file *seq = ctx->meta->seq;

	struct cgroup *cgrp = ctx->cgroup;



	/* epilogue */

	if (cgrp == NULL) {

		BPF_SEQ_PRINTF(seq, "epilogue\n");

		return 0;

	}



	/* prologue */

	if (ctx->meta->seq_num == 0)

		BPF_SEQ_PRINTF(seq, "prologue\n");



	BPF_SEQ_PRINTF(seq, "%8llu\n", cgroup_id(cgrp));



	if (terminal_cgroup == cgroup_id(cgrp))

		return 1;



	return terminate_early ? 1 : 0;

}