diff options
Diffstat (limited to 'tools/testing/selftests/bpf/cgroup_helpers.c')
| -rw-r--r-- | tools/testing/selftests/bpf/cgroup_helpers.c | 751 |
1 files changed, 751 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/cgroup_helpers.c b/tools/testing/selftests/bpf/cgroup_helpers.c new file mode 100644 index 000000000000..20cede4db3ce --- /dev/null +++ b/tools/testing/selftests/bpf/cgroup_helpers.c @@ -0,0 +1,751 @@ +// 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 <sys/xattr.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" +#include "bpf_util.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_pid(buf, path, pid) \ + snprintf(buf, sizeof(buf), "%s%s%d%s", CGROUP_MOUNT_PATH, \ + CGROUP_WORK_DIR, pid, path) + +#define format_cgroup_path(buf, path) \ + format_cgroup_path_pid(buf, path, getpid()) + +#define format_parent_cgroup_path(buf, path) \ + format_cgroup_path_pid(buf, path, getppid()) + +#define format_classid_path_pid(buf, pid) \ + snprintf(buf, sizeof(buf), "%s%s%d", NETCLS_MOUNT_PATH, \ + CGROUP_WORK_DIR, pid) + +#define format_classid_path(buf) \ + format_classid_path_pid(buf, getpid()) + +static __thread bool cgroup_workdir_mounted; + +static void __cleanup_cgroup_environment(void); + +static int __enable_controllers(const char *cgroup_path, const char *controllers) +{ + char path[PATH_MAX + 1]; + char enable[PATH_MAX + 1]; + char *c, *c2; + int fd, cfd; + ssize_t len; + + /* If not controllers are passed, enable all available controllers */ + if (!controllers) { + 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, enable, sizeof(enable) - 1); + if (len < 0) { + close(fd); + log_err("Reading cgroup.controllers: %s", path); + return 1; + } else if (len == 0) { /* No controllers to enable */ + close(fd); + return 0; + } + enable[len] = 0; + close(fd); + } else { + bpf_strlcpy(enable, controllers, sizeof(enable)); + } + + 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(enable, " ", &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; +} + +/** + * enable_controllers() - Enable cgroup v2 controllers + * @relative_path: The cgroup path, relative to the workdir + * @controllers: List of controllers to enable in cgroup.controllers format + * + * + * Enable given cgroup v2 controllers, if @controllers is NULL, enable all + * available controllers. + * + * If successful, 0 is returned. + */ +int enable_controllers(const char *relative_path, const char *controllers) +{ + char cgroup_path[PATH_MAX + 1]; + + format_cgroup_path(cgroup_path, relative_path); + return __enable_controllers(cgroup_path, controllers); +} + +static int __write_cgroup_file(const char *cgroup_path, const char *file, + const char *buf) +{ + char file_path[PATH_MAX + 1]; + int fd; + + snprintf(file_path, sizeof(file_path), "%s/%s", cgroup_path, file); + fd = open(file_path, O_RDWR); + if (fd < 0) { + log_err("Opening %s", file_path); + return 1; + } + + if (dprintf(fd, "%s", buf) <= 0) { + log_err("Writing to %s", file_path); + close(fd); + return 1; + } + close(fd); + return 0; +} + +/** + * write_cgroup_file() - Write to a cgroup file + * @relative_path: The cgroup path, relative to the workdir + * @file: The name of the file in cgroupfs to write to + * @buf: Buffer to write to the file + * + * Write to a file in the given cgroup's directory. + * + * If successful, 0 is returned. + */ +int write_cgroup_file(const char *relative_path, const char *file, + const char *buf) +{ + char cgroup_path[PATH_MAX - 24]; + + format_cgroup_path(cgroup_path, relative_path); + return __write_cgroup_file(cgroup_path, file, buf); +} + +/** + * write_cgroup_file_parent() - Write to a cgroup file in the parent process + * workdir + * @relative_path: The cgroup path, relative to the parent process workdir + * @file: The name of the file in cgroupfs to write to + * @buf: Buffer to write to the file + * + * Write to a file in the given cgroup's directory under the parent process + * workdir. + * + * If successful, 0 is returned. + */ +int write_cgroup_file_parent(const char *relative_path, const char *file, + const char *buf) +{ + char cgroup_path[PATH_MAX - 24]; + + format_parent_cgroup_path(cgroup_path, relative_path); + return __write_cgroup_file(cgroup_path, file, buf); +} + +/** + * 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 (mkdir(CGROUP_MOUNT_PATH, 0777) && errno != EEXIST) { + log_err("mkdir mount"); + return 1; + } + + 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; + } + cgroup_workdir_mounted = true; + + /* 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; + } + + /* Enable all available controllers to increase test coverage */ + if (__enable_controllers(CGROUP_MOUNT_PATH, NULL) || + __enable_controllers(cgroup_workdir, NULL)) + 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 + * @relative_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 *relative_path) +{ + char cgroup_path[PATH_MAX + 1]; + + format_cgroup_path(cgroup_path, relative_path); + return join_cgroup_from_top(cgroup_path); +} + +/** + * join_root_cgroup() - Join the root cgroup + * + * This function joins the root cgroup. + * + * On success, it returns 0, otherwise on failure it returns 1. + */ +int join_root_cgroup(void) +{ + return join_cgroup_from_top(CGROUP_MOUNT_PATH); +} + +/** + * join_parent_cgroup() - Join a cgroup in the parent process workdir + * @relative_path: The cgroup path, relative to parent process workdir, to join + * + * See join_cgroup(). + * + * On success, it returns 0, otherwise on failure it returns 1. + */ +int join_parent_cgroup(const char *relative_path) +{ + char cgroup_path[PATH_MAX + 1]; + + format_parent_cgroup_path(cgroup_path, 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 + * + * This is a helper for cleanup_cgroup_environment() that is responsible for + * deletion of all temporary cgroups that have been created during the test. + */ +static 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); +} + +/** + * cleanup_cgroup_environment() - Cleanup Cgroup Testing Environment + * + * This is an idempotent function to delete all temporary cgroups that + * have been created during the test and unmount 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) +{ + __cleanup_cgroup_environment(); + if (cgroup_workdir_mounted && umount(CGROUP_MOUNT_PATH)) + log_err("umount cgroup2"); + cgroup_workdir_mounted = false; +} + +/** + * get_root_cgroup() - Get the FD of the root cgroup + * + * On success, it returns the file descriptor. On failure, it returns -1. + * If there is a failure, it prints the error to stderr. + */ +int get_root_cgroup(void) +{ + int fd; + + fd = open(CGROUP_MOUNT_PATH, O_RDONLY); + if (fd < 0) { + log_err("Opening root cgroup"); + return -1; + } + return fd; +} + +/* + * remove_cgroup() - Remove a cgroup + * @relative_path: The cgroup path, relative to the workdir, to remove + * + * This function expects a cgroup to already be created, relative to the cgroup + * work dir. It also expects the cgroup doesn't have any children or live + * processes and it removes the cgroup. + * + * On failure, it will print an error to stderr. + */ +void remove_cgroup(const char *relative_path) +{ + char cgroup_path[PATH_MAX + 1]; + + format_cgroup_path(cgroup_path, relative_path); + if (rmdir(cgroup_path)) + log_err("rmdiring cgroup %s .. %s", relative_path, cgroup_path); +} + +/* + * remove_cgroup_pid() - Remove a cgroup setup by process identified by PID + * @relative_path: The cgroup path, relative to the workdir, to remove + * @pid: PID to be used to find cgroup_path + * + * This function expects a cgroup to already be created, relative to the cgroup + * work dir. It also expects the cgroup doesn't have any children or live + * processes and it removes the cgroup. + * + * On failure, it will print an error to stderr. + */ +void remove_cgroup_pid(const char *relative_path, int pid) +{ + char cgroup_path[PATH_MAX + 1]; + + format_cgroup_path_pid(cgroup_path, relative_path, pid); + if (rmdir(cgroup_path)) + log_err("rmdiring cgroup %s .. %s", relative_path, cgroup_path); +} + +/** + * create_and_get_cgroup() - Create a cgroup, relative to workdir, and get the FD + * @relative_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 *relative_path) +{ + char cgroup_path[PATH_MAX + 1]; + int fd; + + format_cgroup_path(cgroup_path, relative_path); + if (mkdir(cgroup_path, 0777) && errno != EEXIST) { + log_err("mkdiring cgroup %s .. %s", relative_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_from_path - Get cgroup id for a particular cgroup path + * @cgroup_workdir: The absolute cgroup path + * + * 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. + */ +static unsigned long long get_cgroup_id_from_path(const char *cgroup_workdir) +{ + int dirfd, err, flags, mount_id, fhsize; + union { + unsigned long long cgid; + unsigned char raw_bytes[8]; + } id; + struct file_handle *fhp, *fhp2; + unsigned long long ret = 0; + + 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; +} + +unsigned long long get_cgroup_id(const char *relative_path) +{ + char cgroup_workdir[PATH_MAX + 1]; + + format_cgroup_path(cgroup_workdir, relative_path); + return get_cgroup_id_from_path(cgroup_workdir); +} + +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 + * + * This function should only be called in a custom mount namespace, e.g. + * created by running setup_cgroup_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")) { + if (errno != EBUSY) { + log_err("mount cgroup net_cls"); + return 1; + } + + if (rmdir(NETCLS_MOUNT_PATH)) { + log_err("rmdir cgroup net_cls"); + return 1; + } + if (umount(CGROUP_MOUNT_DFLT)) { + log_err("umount cgroup base"); + 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 + * + * Writes the classid into the cgroup work dir's net_cls.classid + * file in order to later on trigger socket tagging. + * + * We leverage the current pid as the classid, ensuring unique identification. + * + * 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(void) +{ + 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", getpid()) < 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); +} + +/** + * get_classid_cgroup_id - Get the cgroup id of a net_cls cgroup + */ +unsigned long long get_classid_cgroup_id(void) +{ + char cgroup_workdir[PATH_MAX + 1]; + + format_classid_path(cgroup_workdir); + return get_cgroup_id_from_path(cgroup_workdir); +} + +/** + * get_cgroup1_hierarchy_id - Retrieves the ID of a cgroup1 hierarchy from the cgroup1 subsys name. + * @subsys_name: The cgroup1 subsys name, which can be retrieved from /proc/self/cgroup. It can be + * a named cgroup like "name=systemd", a controller name like "net_cls", or multi-controllers like + * "net_cls,net_prio". + */ +int get_cgroup1_hierarchy_id(const char *subsys_name) +{ + char *c, *c2, *c3, *c4; + bool found = false; + char line[1024]; + FILE *file; + int i, id; + + if (!subsys_name) + return -1; + + file = fopen("/proc/self/cgroup", "r"); + if (!file) { + log_err("fopen /proc/self/cgroup"); + return -1; + } + + while (fgets(line, 1024, file)) { + i = 0; + for (c = strtok_r(line, ":", &c2); c && i < 2; c = strtok_r(NULL, ":", &c2)) { + if (i == 0) { + id = strtol(c, NULL, 10); + } else if (i == 1) { + if (!strcmp(c, subsys_name)) { + found = true; + break; + } + + /* Multiple subsystems may share one single mount point */ + for (c3 = strtok_r(c, ",", &c4); c3; + c3 = strtok_r(NULL, ",", &c4)) { + if (!strcmp(c, subsys_name)) { + found = true; + break; + } + } + } + i++; + } + if (found) + break; + } + fclose(file); + return found ? id : -1; +} + +/** + * open_classid() - Open a cgroupv1 net_cls classid + * + * This function expects the cgroup work dir to be already created, as we + * open it here. + * + * On success, it returns the file descriptor. On failure it returns -1. + */ +int open_classid(void) +{ + char cgroup_workdir[PATH_MAX + 1]; + + format_classid_path(cgroup_workdir); + return open(cgroup_workdir, O_RDONLY); +} |