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Commit f269099a authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov
Browse files

tools/bpf: add a selftest for bpf_get_current_cgroup_id() helper 



Syscall name_to_handle_at() can be used to get cgroup id
for a particular cgroup path in user space. The selftest
got cgroup id from both user and kernel, and compare to
ensure they are equal to each other.

Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent c7ddbbaf

tools/testing/selftests/bpf/.gitignore

+1 −0
Original line number Diff line number Diff line
@@ -18,3 +18,4 @@ urandom_read 
test_btf

test_sockmap

test_lirc_mode2_user

get_cgroup_id_user

tools/testing/selftests/bpf/Makefile

+4 −2
Original line number Diff line number Diff line
@@ -24,7 +24,7 @@ urandom_read: urandom_read.c 
# Order correspond to 'make run_tests' order

TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \

	test_align test_verifier_log test_dev_cgroup test_tcpbpf_user \

	test_sock test_btf test_sockmap test_lirc_mode2_user

	test_sock test_btf test_sockmap test_lirc_mode2_user get_cgroup_id_user



TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test_obj_id.o \

	test_pkt_md_access.o test_xdp_redirect.o test_xdp_meta.o sockmap_parse_prog.o     \
@@ -34,7 +34,8 @@ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test 
	sockmap_tcp_msg_prog.o connect4_prog.o connect6_prog.o test_adjust_tail.o \

	test_btf_haskv.o test_btf_nokv.o test_sockmap_kern.o test_tunnel_kern.o \

	test_get_stack_rawtp.o test_sockmap_kern.o test_sockhash_kern.o \

	test_lwt_seg6local.o sendmsg4_prog.o sendmsg6_prog.o test_lirc_mode2_kern.o

	test_lwt_seg6local.o sendmsg4_prog.o sendmsg6_prog.o test_lirc_mode2_kern.o \

	get_cgroup_id_kern.o



# Order correspond to 'make run_tests' order

TEST_PROGS := test_kmod.sh \
@@ -63,6 +64,7 @@ $(OUTPUT)/test_sock: cgroup_helpers.c 
$(OUTPUT)/test_sock_addr: cgroup_helpers.c

$(OUTPUT)/test_sockmap: cgroup_helpers.c

$(OUTPUT)/test_progs: trace_helpers.c

$(OUTPUT)/get_cgroup_id_user: cgroup_helpers.c



.PHONY: force

tools/testing/selftests/bpf/cgroup_helpers.c

+57 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
#include <sys/types.h>

#include <linux/limits.h>

#include <stdio.h>

#include <stdlib.h>

#include <linux/sched.h>

#include <fcntl.h>

#include <unistd.h>
@@ -176,3 +177,59 @@ int create_and_get_cgroup(char *path) 


	return fd;

}



/**

 * get_cgroup_id() - Get cgroup id for a particular cgroup path

 * @path: The cgroup path, relative to the workdir, to join

 *

 * On success, it returns the cgroup id. On failure it returns 0,

 * which is an invalid cgroup id.

 * If there is a failure, it prints the error to stderr.

 */

unsigned long long get_cgroup_id(char *path)

{

	int dirfd, err, flags, mount_id, fhsize;

	union {

		unsigned long long cgid;

		unsigned char raw_bytes[8];

	} id;

	char cgroup_workdir[PATH_MAX + 1];

	struct file_handle *fhp, *fhp2;

	unsigned long long ret = 0;



	format_cgroup_path(cgroup_workdir, path);



	dirfd = AT_FDCWD;

	flags = 0;

	fhsize = sizeof(*fhp);

	fhp = calloc(1, fhsize);

	if (!fhp) {

		log_err("calloc");

		return 0;

	}

	err = name_to_handle_at(dirfd, cgroup_workdir, fhp, &mount_id, flags);

	if (err >= 0 || fhp->handle_bytes != 8) {

		log_err("name_to_handle_at");

		goto free_mem;

	}



	fhsize = sizeof(struct file_handle) + fhp->handle_bytes;

	fhp2 = realloc(fhp, fhsize);

	if (!fhp2) {

		log_err("realloc");

		goto free_mem;

	}

	err = name_to_handle_at(dirfd, cgroup_workdir, fhp2, &mount_id, flags);

	fhp = fhp2;

	if (err < 0) {

		log_err("name_to_handle_at");

		goto free_mem;

	}



	memcpy(id.raw_bytes, fhp->f_handle, 8);

	ret = id.cgid;



free_mem:

	free(fhp);

	return ret;

}

tools/testing/selftests/bpf/cgroup_helpers.h

+1 −0
Original line number Diff line number Diff line
@@ -13,5 +13,6 @@ int create_and_get_cgroup(char *path); 
int join_cgroup(char *path);

int setup_cgroup_environment(void);

void cleanup_cgroup_environment(void);

unsigned long long get_cgroup_id(char *path);



#endif

tools/testing/selftests/bpf/get_cgroup_id_kern.c

0 → 100644
+28 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

// Copyright (c) 2018 Facebook



#include <linux/bpf.h>

#include "bpf_helpers.h"



struct bpf_map_def SEC("maps") cg_ids = {

	.type = BPF_MAP_TYPE_ARRAY,

	.key_size = sizeof(__u32),

	.value_size = sizeof(__u64),

	.max_entries = 1,

};



SEC("tracepoint/syscalls/sys_enter_nanosleep")

int trace(void *ctx)

{

	__u32 key = 0;

	__u64 *val;



	val = bpf_map_lookup_elem(&cg_ids, &key);

	if (val)

		*val = bpf_get_current_cgroup_id();



	return 0;

}



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

__u32 _version SEC("version") = 1; /* ignored by tracepoints, required by libbpf.a */