1 // SPDX-License-Identifier: GPL-2.0
7 #include <linux/limits.h>
10 #include <linux/sched.h>
16 #include "cgroup_helpers.h"
19 * To avoid relying on the system setup, when setup_cgroup_env is called
20 * we create a new mount namespace, and cgroup namespace. The cgroup2
21 * root is mounted at CGROUP_MOUNT_PATH
23 * Unfortunately, most people don't have cgroupv2 enabled at this point in time.
24 * It's easier to create our own mount namespace and manage it ourselves.
26 * We assume /mnt exists.
29 #define WALK_FD_LIMIT 16
30 #define CGROUP_MOUNT_PATH "/mnt"
31 #define CGROUP_WORK_DIR "/cgroup-test-work-dir"
32 #define format_cgroup_path(buf, path) \
33 snprintf(buf, sizeof(buf), "%s%s%s", CGROUP_MOUNT_PATH, \
34 CGROUP_WORK_DIR, path)
37 * enable_all_controllers() - Enable all available cgroup v2 controllers
39 * Enable all available cgroup v2 controllers in order to increase
42 * If successful, 0 is returned.
44 static int enable_all_controllers(char *cgroup_path)
46 char path[PATH_MAX + 1];
52 snprintf(path, sizeof(path), "%s/cgroup.controllers", cgroup_path);
53 fd = open(path, O_RDONLY);
55 log_err("Opening cgroup.controllers: %s", path);
59 len = read(fd, buf, sizeof(buf) - 1);
62 log_err("Reading cgroup.controllers: %s", path);
68 /* No controllers available? We're probably on cgroup v1. */
72 snprintf(path, sizeof(path), "%s/cgroup.subtree_control", cgroup_path);
73 cfd = open(path, O_RDWR);
75 log_err("Opening cgroup.subtree_control: %s", path);
79 for (c = strtok_r(buf, " ", &c2); c; c = strtok_r(NULL, " ", &c2)) {
80 if (dprintf(cfd, "+%s\n", c) <= 0) {
81 log_err("Enabling controller %s: %s", c, path);
91 * setup_cgroup_environment() - Setup the cgroup environment
93 * After calling this function, cleanup_cgroup_environment should be called
94 * once testing is complete.
96 * This function will print an error to stderr and return 1 if it is unable
97 * to setup the cgroup environment. If setup is successful, 0 is returned.
99 int setup_cgroup_environment(void)
101 char cgroup_workdir[PATH_MAX - 24];
103 format_cgroup_path(cgroup_workdir, "");
105 if (unshare(CLONE_NEWNS)) {
110 if (mount("none", "/", NULL, MS_REC | MS_PRIVATE, NULL)) {
111 log_err("mount fakeroot");
115 if (mount("none", CGROUP_MOUNT_PATH, "cgroup2", 0, NULL) && errno != EBUSY) {
116 log_err("mount cgroup2");
120 /* Cleanup existing failed runs, now that the environment is setup */
121 cleanup_cgroup_environment();
123 if (mkdir(cgroup_workdir, 0777) && errno != EEXIST) {
124 log_err("mkdir cgroup work dir");
128 if (enable_all_controllers(cgroup_workdir))
134 static int nftwfunc(const char *filename, const struct stat *statptr,
135 int fileflags, struct FTW *pfwt)
137 if ((fileflags & FTW_D) && rmdir(filename))
138 log_err("Removing cgroup: %s", filename);
143 static int join_cgroup_from_top(char *cgroup_path)
145 char cgroup_procs_path[PATH_MAX + 1];
146 pid_t pid = getpid();
149 snprintf(cgroup_procs_path, sizeof(cgroup_procs_path),
150 "%s/cgroup.procs", cgroup_path);
152 fd = open(cgroup_procs_path, O_WRONLY);
154 log_err("Opening Cgroup Procs: %s", cgroup_procs_path);
158 if (dprintf(fd, "%d\n", pid) < 0) {
159 log_err("Joining Cgroup");
168 * join_cgroup() - Join a cgroup
169 * @path: The cgroup path, relative to the workdir, to join
171 * This function expects a cgroup to already be created, relative to the cgroup
172 * work dir, and it joins it. For example, passing "/my-cgroup" as the path
173 * would actually put the calling process into the cgroup
174 * "/cgroup-test-work-dir/my-cgroup"
176 * On success, it returns 0, otherwise on failure it returns 1.
178 int join_cgroup(const char *path)
180 char cgroup_path[PATH_MAX + 1];
182 format_cgroup_path(cgroup_path, path);
183 return join_cgroup_from_top(cgroup_path);
187 * cleanup_cgroup_environment() - Cleanup Cgroup Testing Environment
189 * This is an idempotent function to delete all temporary cgroups that
190 * have been created during the test, including the cgroup testing work
193 * At call time, it moves the calling process to the root cgroup, and then
194 * runs the deletion process. It is idempotent, and should not fail, unless
195 * a process is lingering.
197 * On failure, it will print an error to stderr, and try to continue.
199 void cleanup_cgroup_environment(void)
201 char cgroup_workdir[PATH_MAX + 1];
203 format_cgroup_path(cgroup_workdir, "");
204 join_cgroup_from_top(CGROUP_MOUNT_PATH);
205 nftw(cgroup_workdir, nftwfunc, WALK_FD_LIMIT, FTW_DEPTH | FTW_MOUNT);
209 * create_and_get_cgroup() - Create a cgroup, relative to workdir, and get the FD
210 * @path: The cgroup path, relative to the workdir, to join
212 * This function creates a cgroup under the top level workdir and returns the
213 * file descriptor. It is idempotent.
215 * On success, it returns the file descriptor. On failure it returns -1.
216 * If there is a failure, it prints the error to stderr.
218 int create_and_get_cgroup(const char *path)
220 char cgroup_path[PATH_MAX + 1];
223 format_cgroup_path(cgroup_path, path);
224 if (mkdir(cgroup_path, 0777) && errno != EEXIST) {
225 log_err("mkdiring cgroup %s .. %s", path, cgroup_path);
229 fd = open(cgroup_path, O_RDONLY);
231 log_err("Opening Cgroup");
239 * get_cgroup_id() - Get cgroup id for a particular cgroup path
240 * @path: The cgroup path, relative to the workdir, to join
242 * On success, it returns the cgroup id. On failure it returns 0,
243 * which is an invalid cgroup id.
244 * If there is a failure, it prints the error to stderr.
246 unsigned long long get_cgroup_id(const char *path)
248 int dirfd, err, flags, mount_id, fhsize;
250 unsigned long long cgid;
251 unsigned char raw_bytes[8];
253 char cgroup_workdir[PATH_MAX + 1];
254 struct file_handle *fhp, *fhp2;
255 unsigned long long ret = 0;
257 format_cgroup_path(cgroup_workdir, path);
261 fhsize = sizeof(*fhp);
262 fhp = calloc(1, fhsize);
267 err = name_to_handle_at(dirfd, cgroup_workdir, fhp, &mount_id, flags);
268 if (err >= 0 || fhp->handle_bytes != 8) {
269 log_err("name_to_handle_at");
273 fhsize = sizeof(struct file_handle) + fhp->handle_bytes;
274 fhp2 = realloc(fhp, fhsize);
279 err = name_to_handle_at(dirfd, cgroup_workdir, fhp2, &mount_id, flags);
282 log_err("name_to_handle_at");
286 memcpy(id.raw_bytes, fhp->f_handle, 8);