OSCL-LXR linux-6.0.1/​tools/​testing/​selftests/​bpf/​cgroup_helpers.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 #define _GNU_SOURCE
 #include <sched.h>
 #include <sys/mount.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <linux/limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <linux/sched.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <ftw.h>
 
 #include "cgroup_helpers.h"
 
 /*
  * To avoid relying on the system setup, when setup_cgroup_env is called
  * we create a new mount namespace, and cgroup namespace. The cgroupv2
  * root is mounted at CGROUP_MOUNT_PATH. Unfortunately, most people don't
  * have cgroupv2 enabled at this point in time. It's easier to create our
  * own mount namespace and manage it ourselves. We assume /mnt exists.
  *
  * Related cgroupv1 helpers are named *classid*(), since we only use the
  * net_cls controller for tagging net_cls.classid. We assume the default
  * mount under /sys/fs/cgroup/net_cls, which should be the case for the
  * vast majority of users.
  */
 
 #define WALK_FD_LIMIT           16
 
 #define CGROUP_MOUNT_PATH       "/mnt"
 #define CGROUP_MOUNT_DFLT       "/sys/fs/cgroup"
 #define NETCLS_MOUNT_PATH       CGROUP_MOUNT_DFLT "/net_cls"
 #define CGROUP_WORK_DIR         "/cgroup-test-work-dir"
 #define format_cgroup_path(buf, path) \
     snprintf(buf, sizeof(buf), "%s%s%d%s", CGROUP_MOUNT_PATH, \
     CGROUP_WORK_DIR, getpid(), path)
 
 #define format_classid_path(buf)                \
     snprintf(buf, sizeof(buf), "%s%s", NETCLS_MOUNT_PATH,   \
          CGROUP_WORK_DIR)
 
 /**
  * enable_all_controllers() - Enable all available cgroup v2 controllers
  *
  * Enable all available cgroup v2 controllers in order to increase
  * the code coverage.
  *
  * If successful, 0 is returned.
  */
 static int enable_all_controllers(char *cgroup_path)
 {
     char path[PATH_MAX + 1];
     char buf[PATH_MAX];
     char *c, *c2;
     int fd, cfd;
     ssize_t len;
 
     snprintf(path, sizeof(path), "%s/cgroup.controllers", cgroup_path);
     fd = open(path, O_RDONLY);
     if (fd < 0) {
         log_err("Opening cgroup.controllers: %s", path);
         return 1;
     }
 
     len = read(fd, buf, sizeof(buf) - 1);
     if (len < 0) {
         close(fd);
         log_err("Reading cgroup.controllers: %s", path);
         return 1;
     }
     buf[len] = 0;
     close(fd);
 
     /* No controllers available? We're probably on cgroup v1. */
     if (len == 0)
         return 0;
 
     snprintf(path, sizeof(path), "%s/cgroup.subtree_control", cgroup_path);
     cfd = open(path, O_RDWR);
     if (cfd < 0) {
         log_err("Opening cgroup.subtree_control: %s", path);
         return 1;
     }
 
     for (c = strtok_r(buf, " ", &c2); c; c = strtok_r(NULL, " ", &c2)) {
         if (dprintf(cfd, "+%s\n", c) <= 0) {
             log_err("Enabling controller %s: %s", c, path);
             close(cfd);
             return 1;
         }
     }
     close(cfd);
     return 0;
 }
 
 /**
  * setup_cgroup_environment() - Setup the cgroup environment
  *
  * After calling this function, cleanup_cgroup_environment should be called
  * once testing is complete.
  *
  * This function will print an error to stderr and return 1 if it is unable
  * to setup the cgroup environment. If setup is successful, 0 is returned.
  */
 int setup_cgroup_environment(void)
 {
     char cgroup_workdir[PATH_MAX - 24];
 
     format_cgroup_path(cgroup_workdir, "");
 
     if (unshare(CLONE_NEWNS)) {
         log_err("unshare");
         return 1;
     }
 
     if (mount("none", "/", NULL, MS_REC | MS_PRIVATE, NULL)) {
         log_err("mount fakeroot");
         return 1;
     }
 
     if (mount("none", CGROUP_MOUNT_PATH, "cgroup2", 0, NULL) && errno != EBUSY) {
         log_err("mount cgroup2");
         return 1;
     }
 
     /* Cleanup existing failed runs, now that the environment is setup */
     cleanup_cgroup_environment();
 
     if (mkdir(cgroup_workdir, 0777) && errno != EEXIST) {
         log_err("mkdir cgroup work dir");
         return 1;
     }
 
     if (enable_all_controllers(cgroup_workdir))
         return 1;
 
     return 0;
 }
 
 static int nftwfunc(const char *filename, const struct stat *statptr,
             int fileflags, struct FTW *pfwt)
 {
     if ((fileflags & FTW_D) && rmdir(filename))
         log_err("Removing cgroup: %s", filename);
     return 0;
 }
 
 static int join_cgroup_from_top(const char *cgroup_path)
 {
     char cgroup_procs_path[PATH_MAX + 1];
     pid_t pid = getpid();
     int fd, rc = 0;
 
     snprintf(cgroup_procs_path, sizeof(cgroup_procs_path),
          "%s/cgroup.procs", cgroup_path);
 
     fd = open(cgroup_procs_path, O_WRONLY);
     if (fd < 0) {
         log_err("Opening Cgroup Procs: %s", cgroup_procs_path);
         return 1;
     }
 
     if (dprintf(fd, "%d\n", pid) < 0) {
         log_err("Joining Cgroup");
         rc = 1;
     }
 
     close(fd);
     return rc;
 }
 
 /**
  * join_cgroup() - Join a cgroup
  * @path: The cgroup path, relative to the workdir, to join
  *
  * This function expects a cgroup to already be created, relative to the cgroup
  * work dir, and it joins it. For example, passing "/my-cgroup" as the path
  * would actually put the calling process into the cgroup
  * "/cgroup-test-work-dir/my-cgroup"
  *
  * On success, it returns 0, otherwise on failure it returns 1.
  */
 int join_cgroup(const char *path)
 {
     char cgroup_path[PATH_MAX + 1];
 
     format_cgroup_path(cgroup_path, path);
     return join_cgroup_from_top(cgroup_path);
 }
 
 /**
  * cleanup_cgroup_environment() - Cleanup Cgroup Testing Environment
  *
  * This is an idempotent function to delete all temporary cgroups that
  * have been created during the test, including the cgroup testing work
  * directory.
  *
  * At call time, it moves the calling process to the root cgroup, and then
  * runs the deletion process. It is idempotent, and should not fail, unless
  * a process is lingering.
  *
  * On failure, it will print an error to stderr, and try to continue.
  */
 void cleanup_cgroup_environment(void)
 {
     char cgroup_workdir[PATH_MAX + 1];
 
     format_cgroup_path(cgroup_workdir, "");
     join_cgroup_from_top(CGROUP_MOUNT_PATH);
     nftw(cgroup_workdir, nftwfunc, WALK_FD_LIMIT, FTW_DEPTH | FTW_MOUNT);
 }
 
 /**
  * create_and_get_cgroup() - Create a cgroup, relative to workdir, and get the FD
  * @path: The cgroup path, relative to the workdir, to join
  *
  * This function creates a cgroup under the top level workdir and returns the
  * file descriptor. It is idempotent.
  *
  * On success, it returns the file descriptor. On failure it returns -1.
  * If there is a failure, it prints the error to stderr.
  */
 int create_and_get_cgroup(const char *path)
 {
     char cgroup_path[PATH_MAX + 1];
     int fd;
 
     format_cgroup_path(cgroup_path, path);
     if (mkdir(cgroup_path, 0777) && errno != EEXIST) {
         log_err("mkdiring cgroup %s .. %s", path, cgroup_path);
         return -1;
     }
 
     fd = open(cgroup_path, O_RDONLY);
     if (fd < 0) {
         log_err("Opening Cgroup");
         return -1;
     }
 
     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(const 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;
 }
 
 int cgroup_setup_and_join(const char *path) {
     int cg_fd;
 
     if (setup_cgroup_environment()) {
         fprintf(stderr, "Failed to setup cgroup environment\n");
         return -EINVAL;
     }
 
     cg_fd = create_and_get_cgroup(path);
     if (cg_fd < 0) {
         fprintf(stderr, "Failed to create test cgroup\n");
         cleanup_cgroup_environment();
         return cg_fd;
     }
 
     if (join_cgroup(path)) {
         fprintf(stderr, "Failed to join cgroup\n");
         cleanup_cgroup_environment();
         return -EINVAL;
     }
     return cg_fd;
 }
 
 /**
  * setup_classid_environment() - Setup the cgroupv1 net_cls environment
  *
  * After calling this function, cleanup_classid_environment should be called
  * once testing is complete.
  *
  * This function will print an error to stderr and return 1 if it is unable
  * to setup the cgroup environment. If setup is successful, 0 is returned.
  */
 int setup_classid_environment(void)
 {
     char cgroup_workdir[PATH_MAX + 1];
 
     format_classid_path(cgroup_workdir);
 
     if (mount("tmpfs", CGROUP_MOUNT_DFLT, "tmpfs", 0, NULL) &&
         errno != EBUSY) {
         log_err("mount cgroup base");
         return 1;
     }
 
     if (mkdir(NETCLS_MOUNT_PATH, 0777) && errno != EEXIST) {
         log_err("mkdir cgroup net_cls");
         return 1;
     }
 
     if (mount("net_cls", NETCLS_MOUNT_PATH, "cgroup", 0, "net_cls") &&
         errno != EBUSY) {
         log_err("mount cgroup net_cls");
         return 1;
     }
 
     cleanup_classid_environment();
 
     if (mkdir(cgroup_workdir, 0777) && errno != EEXIST) {
         log_err("mkdir cgroup work dir");
         return 1;
     }
 
     return 0;
 }
 
 /**
  * set_classid() - Set a cgroupv1 net_cls classid
  * @id: the numeric classid
  *
  * Writes the passed classid into the cgroup work dir's net_cls.classid
  * file in order to later on trigger socket tagging.
  *
  * On success, it returns 0, otherwise on failure it returns 1. If there
  * is a failure, it prints the error to stderr.
  */
 int set_classid(unsigned int id)
 {
     char cgroup_workdir[PATH_MAX - 42];
     char cgroup_classid_path[PATH_MAX + 1];
     int fd, rc = 0;
 
     format_classid_path(cgroup_workdir);
     snprintf(cgroup_classid_path, sizeof(cgroup_classid_path),
          "%s/net_cls.classid", cgroup_workdir);
 
     fd = open(cgroup_classid_path, O_WRONLY);
     if (fd < 0) {
         log_err("Opening cgroup classid: %s", cgroup_classid_path);
         return 1;
     }
 
     if (dprintf(fd, "%u\n", id) < 0) {
         log_err("Setting cgroup classid");
         rc = 1;
     }
 
     close(fd);
     return rc;
 }
 
 /**
  * join_classid() - Join a cgroupv1 net_cls classid
  *
  * This function expects the cgroup work dir to be already created, as we
  * join it here. This causes the process sockets to be tagged with the given
  * net_cls classid.
  *
  * On success, it returns 0, otherwise on failure it returns 1.
  */
 int join_classid(void)
 {
     char cgroup_workdir[PATH_MAX + 1];
 
     format_classid_path(cgroup_workdir);
     return join_cgroup_from_top(cgroup_workdir);
 }
 
 /**
  * cleanup_classid_environment() - Cleanup the cgroupv1 net_cls environment
  *
  * At call time, it moves the calling process to the root cgroup, and then
  * runs the deletion process.
  *
  * On failure, it will print an error to stderr, and try to continue.
  */
 void cleanup_classid_environment(void)
 {
     char cgroup_workdir[PATH_MAX + 1];
 
     format_classid_path(cgroup_workdir);
     join_cgroup_from_top(NETCLS_MOUNT_PATH);
     nftw(cgroup_workdir, nftwfunc, WALK_FD_LIMIT, FTW_DEPTH | FTW_MOUNT);
 }

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