Commit bacdf5a0 authored by Song Liu's avatar Song Liu Committed by Alexei Starovoitov
Browse files

selftests/bpf: Fix cgroup_xattr/read_cgroupfs_xattr 



cgroup_xattr/read_cgroupfs_xattr has two issues:

1. cgroup_xattr/read_cgroupfs_xattr messes up lo without creating a netns
   first. This causes issue with other tests.

   Fix this by using a different hook (lsm.s/file_open) and not messing
   with lo.

2. cgroup_xattr/read_cgroupfs_xattr sets up cgroups without proper
   mount namespaces.

   Fix this by using the existing cgroup helpers. A new helper
   set_cgroup_xattr() is added to set xattr on cgroup files.

Fixes: f4fba2d6 ("selftests/bpf: Add tests for bpf_cgroup_read_xattr")
Reported-by: default avatarAlexei Starovoitov <ast@kernel.org>
Closes: https://lore.kernel.org/bpf/CAADnVQ+iqMi2HEj_iH7hsx+XJAsqaMWqSDe4tzcGAnehFWA9Sw@mail.gmail.com/


Signed-off-by: default avatarSong Liu <song@kernel.org>
Tested-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Tested-by: default avatarIhor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20250627191221.765921-1-song@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent a5a7b25d

tools/testing/selftests/bpf/cgroup_helpers.c

+21 −0
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
#include <sys/mount.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <sys/xattr.h>

#include <linux/limits.h>

#include <stdio.h>

#include <stdlib.h>
@@ -318,6 +319,26 @@ int join_parent_cgroup(const char *relative_path) 
	return join_cgroup_from_top(cgroup_path);

}



/**

 * set_cgroup_xattr() - Set xattr on a cgroup dir

 * @relative_path: The cgroup path, relative to the workdir, to set xattr

 * @name: xattr name

 * @value: xattr value

 *

 * This function set xattr on cgroup dir.

 *

 * On success, it returns 0, otherwise on failure it returns -1.

 */

int set_cgroup_xattr(const char *relative_path,

		     const char *name,

		     const char *value)

{

	char cgroup_path[PATH_MAX + 1];



	format_cgroup_path(cgroup_path, relative_path);

	return setxattr(cgroup_path, name, value, strlen(value) + 1, 0);

}



/**

 * __cleanup_cgroup_environment() - Delete temporary cgroups

 *

tools/testing/selftests/bpf/cgroup_helpers.h

+4 −0
Original line number Diff line number Diff line
@@ -26,6 +26,10 @@ int join_cgroup(const char *relative_path); 
int join_root_cgroup(void);

int join_parent_cgroup(const char *relative_path);



int set_cgroup_xattr(const char *relative_path,

		     const char *name,

		     const char *value);



int setup_cgroup_environment(void);

void cleanup_cgroup_environment(void);

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

+22 −95
Original line number Diff line number Diff line
@@ -7,133 +7,60 @@ 
#include <string.h>

#include <unistd.h>

#include <sys/socket.h>

#include <sys/xattr.h>



#include <test_progs.h>

#include "cgroup_helpers.h"



#include "read_cgroupfs_xattr.skel.h"

#include "cgroup_read_xattr.skel.h"



#define CGROUP_FS_ROOT "/sys/fs/cgroup/"

#define CGROUP_FS_PARENT CGROUP_FS_ROOT "foo/"

#define CGROUP_FS_PARENT "foo/"

#define CGROUP_FS_CHILD CGROUP_FS_PARENT "bar/"



static int move_pid_to_cgroup(const char *cgroup_folder, pid_t pid)

{

	char filename[128];

	char pid_str[64];

	int procs_fd;

	int ret;



	snprintf(filename, sizeof(filename), "%scgroup.procs", cgroup_folder);

	snprintf(pid_str, sizeof(pid_str), "%d", pid);



	procs_fd = open(filename, O_WRONLY | O_APPEND);

	if (!ASSERT_OK_FD(procs_fd, "open"))

		return -1;



	ret = write(procs_fd, pid_str, strlen(pid_str));

	close(procs_fd);

	if (!ASSERT_GT(ret, 0, "write cgroup.procs"))

		return -1;

	return 0;

}



static void reset_cgroups_and_lo(void)

{

	rmdir(CGROUP_FS_CHILD);

	rmdir(CGROUP_FS_PARENT);

	system("ip addr del 1.1.1.1/32 dev lo");

	system("ip link set dev lo down");

}

#define TMP_FILE "/tmp/selftests_cgroup_xattr"



static const char xattr_value_a[] = "bpf_selftest_value_a";

static const char xattr_value_b[] = "bpf_selftest_value_b";

static const char xattr_name[] = "user.bpf_test";



static int setup_cgroups_and_lo(void)

{

	int err;



	err = mkdir(CGROUP_FS_PARENT, 0755);

	if (!ASSERT_OK(err, "mkdir 1"))

		goto error;

	err = mkdir(CGROUP_FS_CHILD, 0755);

	if (!ASSERT_OK(err, "mkdir 2"))

		goto error;



	err = setxattr(CGROUP_FS_PARENT, xattr_name, xattr_value_a,

		       strlen(xattr_value_a) + 1, 0);

	if (!ASSERT_OK(err, "setxattr 1"))

		goto error;



	err = setxattr(CGROUP_FS_CHILD, xattr_name, xattr_value_b,

		       strlen(xattr_value_b) + 1, 0);

	if (!ASSERT_OK(err, "setxattr 2"))

		goto error;



	err = system("ip link set dev lo up");

	if (!ASSERT_OK(err, "lo up"))

		goto error;



	err = system("ip addr add 1.1.1.1 dev lo");

	if (!ASSERT_OK(err, "lo addr v4"))

		goto error;



	err = write_sysctl("/proc/sys/net/ipv4/ping_group_range", "0 0");

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

		goto error;



	return 0;

error:

	reset_cgroups_and_lo();

	return err;

}



static void test_read_cgroup_xattr(void)

{

	struct sockaddr_in sa4 = {

		.sin_family = AF_INET,

		.sin_addr.s_addr = htonl(INADDR_LOOPBACK),

	};

	int tmp_fd, parent_cgroup_fd = -1, child_cgroup_fd = -1;

	struct read_cgroupfs_xattr *skel = NULL;

	pid_t pid = gettid();

	int sock_fd = -1;

	int connect_fd = -1;



	if (!ASSERT_OK(setup_cgroups_and_lo(), "setup_cgroups_and_lo"))

	parent_cgroup_fd = test__join_cgroup(CGROUP_FS_PARENT);

	if (!ASSERT_OK_FD(parent_cgroup_fd, "create parent cgroup"))

		return;

	if (!ASSERT_OK(move_pid_to_cgroup(CGROUP_FS_CHILD, pid),

		       "move_pid_to_cgroup"))

	if (!ASSERT_OK(set_cgroup_xattr(CGROUP_FS_PARENT, xattr_name, xattr_value_a),

		       "set parent xattr"))

		goto out;



	child_cgroup_fd = test__join_cgroup(CGROUP_FS_CHILD);

	if (!ASSERT_OK_FD(child_cgroup_fd, "create child cgroup"))

		goto out;

	if (!ASSERT_OK(set_cgroup_xattr(CGROUP_FS_CHILD, xattr_name, xattr_value_b),

		       "set child xattr"))

		goto out;



	skel = read_cgroupfs_xattr__open_and_load();

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

		goto out;



	skel->bss->target_pid = pid;

	skel->bss->target_pid = gettid();



	if (!ASSERT_OK(read_cgroupfs_xattr__attach(skel), "read_cgroupfs_xattr__attach"))

		goto out;



	sock_fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_ICMP);

	if (!ASSERT_OK_FD(sock_fd, "sock create"))

		goto out;



	connect_fd = connect(sock_fd, &sa4, sizeof(sa4));

	if (!ASSERT_OK_FD(connect_fd, "connect 1"))

		goto out;

	close(connect_fd);

	tmp_fd = open(TMP_FILE, O_RDONLY | O_CREAT);

	ASSERT_OK_FD(tmp_fd, "open tmp file");

	close(tmp_fd);



	ASSERT_TRUE(skel->bss->found_value_a, "found_value_a");

	ASSERT_TRUE(skel->bss->found_value_b, "found_value_b");



out:

	close(connect_fd);

	close(sock_fd);

	close(child_cgroup_fd);

	close(parent_cgroup_fd);

	read_cgroupfs_xattr__destroy(skel);

	move_pid_to_cgroup(CGROUP_FS_ROOT, pid);

	reset_cgroups_and_lo();

	unlink(TMP_FILE);

}



void test_cgroup_xattr(void)

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

+2 −2
Original line number Diff line number Diff line
@@ -17,8 +17,8 @@ static const char expected_value_b[] = "bpf_selftest_value_b"; 
bool found_value_a;

bool found_value_b;



SEC("lsm.s/socket_connect")

int BPF_PROG(test_socket_connect)

SEC("lsm.s/file_open")

int BPF_PROG(test_file_open)

{

	u64 cgrp_id = bpf_get_current_cgroup_id();

	struct cgroup_subsys_state *css, *tmp;