| // SPDX-License-Identifier: GPL-2.0-only |
| #include "cgroup-internal.h" |
| |
| #include <linux/ctype.h> |
| #include <linux/kmod.h> |
| #include <linux/sort.h> |
| #include <linux/delay.h> |
| #include <linux/mm.h> |
| #include <linux/sched/signal.h> |
| #include <linux/sched/task.h> |
| #include <linux/magic.h> |
| #include <linux/slab.h> |
| #include <linux/vmalloc.h> |
| #include <linux/delayacct.h> |
| #include <linux/pid_namespace.h> |
| #include <linux/cgroupstats.h> |
| #include <linux/fs_parser.h> |
| |
| #include <trace/events/cgroup.h> |
| |
| /* |
| * pidlists linger the following amount before being destroyed. The goal |
| * is avoiding frequent destruction in the middle of consecutive read calls |
| * Expiring in the middle is a performance problem not a correctness one. |
| * 1 sec should be enough. |
| */ |
| #define CGROUP_PIDLIST_DESTROY_DELAY HZ |
| |
| /* Controllers blocked by the commandline in v1 */ |
| static u16 cgroup_no_v1_mask; |
| |
| /* disable named v1 mounts */ |
| static bool cgroup_no_v1_named; |
| |
| /* |
| * pidlist destructions need to be flushed on cgroup destruction. Use a |
| * separate workqueue as flush domain. |
| */ |
| static struct workqueue_struct *cgroup_pidlist_destroy_wq; |
| |
| /* protects cgroup_subsys->release_agent_path */ |
| static DEFINE_SPINLOCK(release_agent_path_lock); |
| |
| bool cgroup1_ssid_disabled(int ssid) |
| { |
| return cgroup_no_v1_mask & (1 << ssid); |
| } |
| |
| /** |
| * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' |
| * @from: attach to all cgroups of a given task |
| * @tsk: the task to be attached |
| * |
| * Return: %0 on success or a negative errno code on failure |
| */ |
| int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) |
| { |
| struct cgroup_root *root; |
| int retval = 0; |
| |
| mutex_lock(&cgroup_mutex); |
| percpu_down_write(&cgroup_threadgroup_rwsem); |
| for_each_root(root) { |
| struct cgroup *from_cgrp; |
| |
| spin_lock_irq(&css_set_lock); |
| from_cgrp = task_cgroup_from_root(from, root); |
| spin_unlock_irq(&css_set_lock); |
| |
| retval = cgroup_attach_task(from_cgrp, tsk, false); |
| if (retval) |
| break; |
| } |
| percpu_up_write(&cgroup_threadgroup_rwsem); |
| mutex_unlock(&cgroup_mutex); |
| |
| return retval; |
| } |
| EXPORT_SYMBOL_GPL(cgroup_attach_task_all); |
| |
| /** |
| * cgroup_transfer_tasks - move tasks from one cgroup to another |
| * @to: cgroup to which the tasks will be moved |
| * @from: cgroup in which the tasks currently reside |
| * |
| * Locking rules between cgroup_post_fork() and the migration path |
| * guarantee that, if a task is forking while being migrated, the new child |
| * is guaranteed to be either visible in the source cgroup after the |
| * parent's migration is complete or put into the target cgroup. No task |
| * can slip out of migration through forking. |
| * |
| * Return: %0 on success or a negative errno code on failure |
| */ |
| int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) |
| { |
| DEFINE_CGROUP_MGCTX(mgctx); |
| struct cgrp_cset_link *link; |
| struct css_task_iter it; |
| struct task_struct *task; |
| int ret; |
| |
| if (cgroup_on_dfl(to)) |
| return -EINVAL; |
| |
| ret = cgroup_migrate_vet_dst(to); |
| if (ret) |
| return ret; |
| |
| mutex_lock(&cgroup_mutex); |
| |
| percpu_down_write(&cgroup_threadgroup_rwsem); |
| |
| /* all tasks in @from are being moved, all csets are source */ |
| spin_lock_irq(&css_set_lock); |
| list_for_each_entry(link, &from->cset_links, cset_link) |
| cgroup_migrate_add_src(link->cset, to, &mgctx); |
| spin_unlock_irq(&css_set_lock); |
| |
| ret = cgroup_migrate_prepare_dst(&mgctx); |
| if (ret) |
| goto out_err; |
| |
| /* |
| * Migrate tasks one-by-one until @from is empty. This fails iff |
| * ->can_attach() fails. |
| */ |
| do { |
| css_task_iter_start(&from->self, 0, &it); |
| |
| do { |
| task = css_task_iter_next(&it); |
| } while (task && (task->flags & PF_EXITING)); |
| |
| if (task) |
| get_task_struct(task); |
| css_task_iter_end(&it); |
| |
| if (task) { |
| ret = cgroup_migrate(task, false, &mgctx); |
| if (!ret) |
| TRACE_CGROUP_PATH(transfer_tasks, to, task, false); |
| put_task_struct(task); |
| } |
| } while (task && !ret); |
| out_err: |
| cgroup_migrate_finish(&mgctx); |
| percpu_up_write(&cgroup_threadgroup_rwsem); |
| mutex_unlock(&cgroup_mutex); |
| return ret; |
| } |
| |
| /* |
| * Stuff for reading the 'tasks'/'procs' files. |
| * |
| * Reading this file can return large amounts of data if a cgroup has |
| * *lots* of attached tasks. So it may need several calls to read(), |
| * but we cannot guarantee that the information we produce is correct |
| * unless we produce it entirely atomically. |
| * |
| */ |
| |
| /* which pidlist file are we talking about? */ |
| enum cgroup_filetype { |
| CGROUP_FILE_PROCS, |
| CGROUP_FILE_TASKS, |
| }; |
| |
| /* |
| * A pidlist is a list of pids that virtually represents the contents of one |
| * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists, |
| * a pair (one each for procs, tasks) for each pid namespace that's relevant |
| * to the cgroup. |
| */ |
| struct cgroup_pidlist { |
| /* |
| * used to find which pidlist is wanted. doesn't change as long as |
| * this particular list stays in the list. |
| */ |
| struct { enum cgroup_filetype type; struct pid_namespace *ns; } key; |
| /* array of xids */ |
| pid_t *list; |
| /* how many elements the above list has */ |
| int length; |
| /* each of these stored in a list by its cgroup */ |
| struct list_head links; |
| /* pointer to the cgroup we belong to, for list removal purposes */ |
| struct cgroup *owner; |
| /* for delayed destruction */ |
| struct delayed_work destroy_dwork; |
| }; |
| |
| /* |
| * Used to destroy all pidlists lingering waiting for destroy timer. None |
| * should be left afterwards. |
| */ |
| void cgroup1_pidlist_destroy_all(struct cgroup *cgrp) |
| { |
| struct cgroup_pidlist *l, *tmp_l; |
| |
| mutex_lock(&cgrp->pidlist_mutex); |
| list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links) |
| mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0); |
| mutex_unlock(&cgrp->pidlist_mutex); |
| |
| flush_workqueue(cgroup_pidlist_destroy_wq); |
| BUG_ON(!list_empty(&cgrp->pidlists)); |
| } |
| |
| static void cgroup_pidlist_destroy_work_fn(struct work_struct *work) |
| { |
| struct delayed_work *dwork = to_delayed_work(work); |
| struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist, |
| destroy_dwork); |
| struct cgroup_pidlist *tofree = NULL; |
| |
| mutex_lock(&l->owner->pidlist_mutex); |
| |
| /* |
| * Destroy iff we didn't get queued again. The state won't change |
| * as destroy_dwork can only be queued while locked. |
| */ |
| if (!delayed_work_pending(dwork)) { |
| list_del(&l->links); |
| kvfree(l->list); |
| put_pid_ns(l->key.ns); |
| tofree = l; |
| } |
| |
| mutex_unlock(&l->owner->pidlist_mutex); |
| kfree(tofree); |
| } |
| |
| /* |
| * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries |
| * Returns the number of unique elements. |
| */ |
| static int pidlist_uniq(pid_t *list, int length) |
| { |
| int src, dest = 1; |
| |
| /* |
| * we presume the 0th element is unique, so i starts at 1. trivial |
| * edge cases first; no work needs to be done for either |
| */ |
| if (length == 0 || length == 1) |
| return length; |
| /* src and dest walk down the list; dest counts unique elements */ |
| for (src = 1; src < length; src++) { |
| /* find next unique element */ |
| while (list[src] == list[src-1]) { |
| src++; |
| if (src == length) |
| goto after; |
| } |
| /* dest always points to where the next unique element goes */ |
| list[dest] = list[src]; |
| dest++; |
| } |
| after: |
| return dest; |
| } |
| |
| /* |
| * The two pid files - task and cgroup.procs - guaranteed that the result |
| * is sorted, which forced this whole pidlist fiasco. As pid order is |
| * different per namespace, each namespace needs differently sorted list, |
| * making it impossible to use, for example, single rbtree of member tasks |
| * sorted by task pointer. As pidlists can be fairly large, allocating one |
| * per open file is dangerous, so cgroup had to implement shared pool of |
| * pidlists keyed by cgroup and namespace. |
| */ |
| static int cmppid(const void *a, const void *b) |
| { |
| return *(pid_t *)a - *(pid_t *)b; |
| } |
| |
| static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, |
| enum cgroup_filetype type) |
| { |
| struct cgroup_pidlist *l; |
| /* don't need task_nsproxy() if we're looking at ourself */ |
| struct pid_namespace *ns = task_active_pid_ns(current); |
| |
| lockdep_assert_held(&cgrp->pidlist_mutex); |
| |
| list_for_each_entry(l, &cgrp->pidlists, links) |
| if (l->key.type == type && l->key.ns == ns) |
| return l; |
| return NULL; |
| } |
| |
| /* |
| * find the appropriate pidlist for our purpose (given procs vs tasks) |
| * returns with the lock on that pidlist already held, and takes care |
| * of the use count, or returns NULL with no locks held if we're out of |
| * memory. |
| */ |
| static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp, |
| enum cgroup_filetype type) |
| { |
| struct cgroup_pidlist *l; |
| |
| lockdep_assert_held(&cgrp->pidlist_mutex); |
| |
| l = cgroup_pidlist_find(cgrp, type); |
| if (l) |
| return l; |
| |
| /* entry not found; create a new one */ |
| l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); |
| if (!l) |
| return l; |
| |
| INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn); |
| l->key.type = type; |
| /* don't need task_nsproxy() if we're looking at ourself */ |
| l->key.ns = get_pid_ns(task_active_pid_ns(current)); |
| l->owner = cgrp; |
| list_add(&l->links, &cgrp->pidlists); |
| return l; |
| } |
| |
| /* |
| * Load a cgroup's pidarray with either procs' tgids or tasks' pids |
| */ |
| static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, |
| struct cgroup_pidlist **lp) |
| { |
| pid_t *array; |
| int length; |
| int pid, n = 0; /* used for populating the array */ |
| struct css_task_iter it; |
| struct task_struct *tsk; |
| struct cgroup_pidlist *l; |
| |
| lockdep_assert_held(&cgrp->pidlist_mutex); |
| |
| /* |
| * If cgroup gets more users after we read count, we won't have |
| * enough space - tough. This race is indistinguishable to the |
| * caller from the case that the additional cgroup users didn't |
| * show up until sometime later on. |
| */ |
| length = cgroup_task_count(cgrp); |
| array = kvmalloc_array(length, sizeof(pid_t), GFP_KERNEL); |
| if (!array) |
| return -ENOMEM; |
| /* now, populate the array */ |
| css_task_iter_start(&cgrp->self, 0, &it); |
| while ((tsk = css_task_iter_next(&it))) { |
| if (unlikely(n == length)) |
| break; |
| /* get tgid or pid for procs or tasks file respectively */ |
| if (type == CGROUP_FILE_PROCS) |
| pid = task_tgid_vnr(tsk); |
| else |
| pid = task_pid_vnr(tsk); |
| if (pid > 0) /* make sure to only use valid results */ |
| array[n++] = pid; |
| } |
| css_task_iter_end(&it); |
| length = n; |
| /* now sort & (if procs) strip out duplicates */ |
| sort(array, length, sizeof(pid_t), cmppid, NULL); |
| if (type == CGROUP_FILE_PROCS) |
| length = pidlist_uniq(array, length); |
| |
| l = cgroup_pidlist_find_create(cgrp, type); |
| if (!l) { |
| kvfree(array); |
| return -ENOMEM; |
| } |
| |
| /* store array, freeing old if necessary */ |
| kvfree(l->list); |
| l->list = array; |
| l->length = length; |
| *lp = l; |
| return 0; |
| } |
| |
| /* |
| * seq_file methods for the tasks/procs files. The seq_file position is the |
| * next pid to display; the seq_file iterator is a pointer to the pid |
| * in the cgroup->l->list array. |
| */ |
| |
| static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) |
| { |
| /* |
| * Initially we receive a position value that corresponds to |
| * one more than the last pid shown (or 0 on the first call or |
| * after a seek to the start). Use a binary-search to find the |
| * next pid to display, if any |
| */ |
| struct kernfs_open_file *of = s->private; |
| struct cgroup_file_ctx *ctx = of->priv; |
| struct cgroup *cgrp = seq_css(s)->cgroup; |
| struct cgroup_pidlist *l; |
| enum cgroup_filetype type = seq_cft(s)->private; |
| int index = 0, pid = *pos; |
| int *iter, ret; |
| |
| mutex_lock(&cgrp->pidlist_mutex); |
| |
| /* |
| * !NULL @ctx->procs1.pidlist indicates that this isn't the first |
| * start() after open. If the matching pidlist is around, we can use |
| * that. Look for it. Note that @ctx->procs1.pidlist can't be used |
| * directly. It could already have been destroyed. |
| */ |
| if (ctx->procs1.pidlist) |
| ctx->procs1.pidlist = cgroup_pidlist_find(cgrp, type); |
| |
| /* |
| * Either this is the first start() after open or the matching |
| * pidlist has been destroyed inbetween. Create a new one. |
| */ |
| if (!ctx->procs1.pidlist) { |
| ret = pidlist_array_load(cgrp, type, &ctx->procs1.pidlist); |
| if (ret) |
| return ERR_PTR(ret); |
| } |
| l = ctx->procs1.pidlist; |
| |
| if (pid) { |
| int end = l->length; |
| |
| while (index < end) { |
| int mid = (index + end) / 2; |
| if (l->list[mid] == pid) { |
| index = mid; |
| break; |
| } else if (l->list[mid] <= pid) |
| index = mid + 1; |
| else |
| end = mid; |
| } |
| } |
| /* If we're off the end of the array, we're done */ |
| if (index >= l->length) |
| return NULL; |
| /* Update the abstract position to be the actual pid that we found */ |
| iter = l->list + index; |
| *pos = *iter; |
| return iter; |
| } |
| |
| static void cgroup_pidlist_stop(struct seq_file *s, void *v) |
| { |
| struct kernfs_open_file *of = s->private; |
| struct cgroup_file_ctx *ctx = of->priv; |
| struct cgroup_pidlist *l = ctx->procs1.pidlist; |
| |
| if (l) |
| mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, |
| CGROUP_PIDLIST_DESTROY_DELAY); |
| mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex); |
| } |
| |
| static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) |
| { |
| struct kernfs_open_file *of = s->private; |
| struct cgroup_file_ctx *ctx = of->priv; |
| struct cgroup_pidlist *l = ctx->procs1.pidlist; |
| pid_t *p = v; |
| pid_t *end = l->list + l->length; |
| /* |
| * Advance to the next pid in the array. If this goes off the |
| * end, we're done |
| */ |
| p++; |
| if (p >= end) { |
| (*pos)++; |
| return NULL; |
| } else { |
| *pos = *p; |
| return p; |
| } |
| } |
| |
| static int cgroup_pidlist_show(struct seq_file *s, void *v) |
| { |
| seq_printf(s, "%d\n", *(int *)v); |
| |
| return 0; |
| } |
| |
| static ssize_t __cgroup1_procs_write(struct kernfs_open_file *of, |
| char *buf, size_t nbytes, loff_t off, |
| bool threadgroup) |
| { |
| struct cgroup *cgrp; |
| struct task_struct *task; |
| const struct cred *cred, *tcred; |
| ssize_t ret; |
| bool locked; |
| |
| cgrp = cgroup_kn_lock_live(of->kn, false); |
| if (!cgrp) |
| return -ENODEV; |
| |
| task = cgroup_procs_write_start(buf, threadgroup, &locked); |
| ret = PTR_ERR_OR_ZERO(task); |
| if (ret) |
| goto out_unlock; |
| |
| /* |
| * Even if we're attaching all tasks in the thread group, we only need |
| * to check permissions on one of them. Check permissions using the |
| * credentials from file open to protect against inherited fd attacks. |
| */ |
| cred = of->file->f_cred; |
| tcred = get_task_cred(task); |
| if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) && |
| !uid_eq(cred->euid, tcred->uid) && |
| !uid_eq(cred->euid, tcred->suid)) |
| ret = -EACCES; |
| put_cred(tcred); |
| if (ret) |
| goto out_finish; |
| |
| ret = cgroup_attach_task(cgrp, task, threadgroup); |
| |
| out_finish: |
| cgroup_procs_write_finish(task, locked); |
| out_unlock: |
| cgroup_kn_unlock(of->kn); |
| |
| return ret ?: nbytes; |
| } |
| |
| static ssize_t cgroup1_procs_write(struct kernfs_open_file *of, |
| char *buf, size_t nbytes, loff_t off) |
| { |
| return __cgroup1_procs_write(of, buf, nbytes, off, true); |
| } |
| |
| static ssize_t cgroup1_tasks_write(struct kernfs_open_file *of, |
| char *buf, size_t nbytes, loff_t off) |
| { |
| return __cgroup1_procs_write(of, buf, nbytes, off, false); |
| } |
| |
| static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of, |
| char *buf, size_t nbytes, loff_t off) |
| { |
| struct cgroup *cgrp; |
| struct cgroup_file_ctx *ctx; |
| |
| BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); |
| |
| /* |
| * Release agent gets called with all capabilities, |
| * require capabilities to set release agent. |
| */ |
| ctx = of->priv; |
| if ((ctx->ns->user_ns != &init_user_ns) || |
| !file_ns_capable(of->file, &init_user_ns, CAP_SYS_ADMIN)) |
| return -EPERM; |
| |
| cgrp = cgroup_kn_lock_live(of->kn, false); |
| if (!cgrp) |
| return -ENODEV; |
| spin_lock(&release_agent_path_lock); |
| strlcpy(cgrp->root->release_agent_path, strstrip(buf), |
| sizeof(cgrp->root->release_agent_path)); |
| spin_unlock(&release_agent_path_lock); |
| cgroup_kn_unlock(of->kn); |
| return nbytes; |
| } |
| |
| static int cgroup_release_agent_show(struct seq_file *seq, void *v) |
| { |
| struct cgroup *cgrp = seq_css(seq)->cgroup; |
| |
| spin_lock(&release_agent_path_lock); |
| seq_puts(seq, cgrp->root->release_agent_path); |
| spin_unlock(&release_agent_path_lock); |
| seq_putc(seq, '\n'); |
| return 0; |
| } |
| |
| static int cgroup_sane_behavior_show(struct seq_file *seq, void *v) |
| { |
| seq_puts(seq, "0\n"); |
| return 0; |
| } |
| |
| static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css, |
| struct cftype *cft) |
| { |
| return notify_on_release(css->cgroup); |
| } |
| |
| static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css, |
| struct cftype *cft, u64 val) |
| { |
| if (val) |
| set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
| else |
| clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
| return 0; |
| } |
| |
| static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css, |
| struct cftype *cft) |
| { |
| return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
| } |
| |
| static int cgroup_clone_children_write(struct cgroup_subsys_state *css, |
| struct cftype *cft, u64 val) |
| { |
| if (val) |
| set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
| else |
| clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
| return 0; |
| } |
| |
| /* cgroup core interface files for the legacy hierarchies */ |
| struct cftype cgroup1_base_files[] = { |
| { |
| .name = "cgroup.procs", |
| .seq_start = cgroup_pidlist_start, |
| .seq_next = cgroup_pidlist_next, |
| .seq_stop = cgroup_pidlist_stop, |
| .seq_show = cgroup_pidlist_show, |
| .private = CGROUP_FILE_PROCS, |
| .write = cgroup1_procs_write, |
| }, |
| { |
| .name = "cgroup.clone_children", |
| .read_u64 = cgroup_clone_children_read, |
| .write_u64 = cgroup_clone_children_write, |
| }, |
| { |
| .name = "cgroup.sane_behavior", |
| .flags = CFTYPE_ONLY_ON_ROOT, |
| .seq_show = cgroup_sane_behavior_show, |
| }, |
| { |
| .name = "tasks", |
| .seq_start = cgroup_pidlist_start, |
| .seq_next = cgroup_pidlist_next, |
| .seq_stop = cgroup_pidlist_stop, |
| .seq_show = cgroup_pidlist_show, |
| .private = CGROUP_FILE_TASKS, |
| .write = cgroup1_tasks_write, |
| }, |
| { |
| .name = "notify_on_release", |
| .read_u64 = cgroup_read_notify_on_release, |
| .write_u64 = cgroup_write_notify_on_release, |
| }, |
| { |
| .name = "release_agent", |
| .flags = CFTYPE_ONLY_ON_ROOT, |
| .seq_show = cgroup_release_agent_show, |
| .write = cgroup_release_agent_write, |
| .max_write_len = PATH_MAX - 1, |
| }, |
| { } /* terminate */ |
| }; |
| |
| /* Display information about each subsystem and each hierarchy */ |
| int proc_cgroupstats_show(struct seq_file *m, void *v) |
| { |
| struct cgroup_subsys *ss; |
| int i; |
| |
| seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); |
| /* |
| * Grab the subsystems state racily. No need to add avenue to |
| * cgroup_mutex contention. |
| */ |
| |
| for_each_subsys(ss, i) |
| seq_printf(m, "%s\t%d\t%d\t%d\n", |
| ss->legacy_name, ss->root->hierarchy_id, |
| atomic_read(&ss->root->nr_cgrps), |
| cgroup_ssid_enabled(i)); |
| |
| return 0; |
| } |
| |
| /** |
| * cgroupstats_build - build and fill cgroupstats |
| * @stats: cgroupstats to fill information into |
| * @dentry: A dentry entry belonging to the cgroup for which stats have |
| * been requested. |
| * |
| * Build and fill cgroupstats so that taskstats can export it to user |
| * space. |
| * |
| * Return: %0 on success or a negative errno code on failure |
| */ |
| int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) |
| { |
| struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
| struct cgroup *cgrp; |
| struct css_task_iter it; |
| struct task_struct *tsk; |
| |
| /* it should be kernfs_node belonging to cgroupfs and is a directory */ |
| if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || |
| kernfs_type(kn) != KERNFS_DIR) |
| return -EINVAL; |
| |
| /* |
| * We aren't being called from kernfs and there's no guarantee on |
| * @kn->priv's validity. For this and css_tryget_online_from_dir(), |
| * @kn->priv is RCU safe. Let's do the RCU dancing. |
| */ |
| rcu_read_lock(); |
| cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv); |
| if (!cgrp || !cgroup_tryget(cgrp)) { |
| rcu_read_unlock(); |
| return -ENOENT; |
| } |
| rcu_read_unlock(); |
| |
| css_task_iter_start(&cgrp->self, 0, &it); |
| while ((tsk = css_task_iter_next(&it))) { |
| switch (READ_ONCE(tsk->__state)) { |
| case TASK_RUNNING: |
| stats->nr_running++; |
| break; |
| case TASK_INTERRUPTIBLE: |
| stats->nr_sleeping++; |
| break; |
| case TASK_UNINTERRUPTIBLE: |
| stats->nr_uninterruptible++; |
| break; |
| case TASK_STOPPED: |
| stats->nr_stopped++; |
| break; |
| default: |
| if (tsk->in_iowait) |
| stats->nr_io_wait++; |
| break; |
| } |
| } |
| css_task_iter_end(&it); |
| |
| cgroup_put(cgrp); |
| return 0; |
| } |
| |
| void cgroup1_check_for_release(struct cgroup *cgrp) |
| { |
| if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) && |
| !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp)) |
| schedule_work(&cgrp->release_agent_work); |
| } |
| |
| /* |
| * Notify userspace when a cgroup is released, by running the |
| * configured release agent with the name of the cgroup (path |
| * relative to the root of cgroup file system) as the argument. |
| * |
| * Most likely, this user command will try to rmdir this cgroup. |
| * |
| * This races with the possibility that some other task will be |
| * attached to this cgroup before it is removed, or that some other |
| * user task will 'mkdir' a child cgroup of this cgroup. That's ok. |
| * The presumed 'rmdir' will fail quietly if this cgroup is no longer |
| * unused, and this cgroup will be reprieved from its death sentence, |
| * to continue to serve a useful existence. Next time it's released, |
| * we will get notified again, if it still has 'notify_on_release' set. |
| * |
| * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which |
| * means only wait until the task is successfully execve()'d. The |
| * separate release agent task is forked by call_usermodehelper(), |
| * then control in this thread returns here, without waiting for the |
| * release agent task. We don't bother to wait because the caller of |
| * this routine has no use for the exit status of the release agent |
| * task, so no sense holding our caller up for that. |
| */ |
| void cgroup1_release_agent(struct work_struct *work) |
| { |
| struct cgroup *cgrp = |
| container_of(work, struct cgroup, release_agent_work); |
| char *pathbuf, *agentbuf; |
| char *argv[3], *envp[3]; |
| int ret; |
| |
| /* snoop agent path and exit early if empty */ |
| if (!cgrp->root->release_agent_path[0]) |
| return; |
| |
| /* prepare argument buffers */ |
| pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); |
| agentbuf = kmalloc(PATH_MAX, GFP_KERNEL); |
| if (!pathbuf || !agentbuf) |
| goto out_free; |
| |
| spin_lock(&release_agent_path_lock); |
| strlcpy(agentbuf, cgrp->root->release_agent_path, PATH_MAX); |
| spin_unlock(&release_agent_path_lock); |
| if (!agentbuf[0]) |
| goto out_free; |
| |
| ret = cgroup_path_ns(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns); |
| if (ret < 0 || ret >= PATH_MAX) |
| goto out_free; |
| |
| argv[0] = agentbuf; |
| argv[1] = pathbuf; |
| argv[2] = NULL; |
| |
| /* minimal command environment */ |
| envp[0] = "HOME=/"; |
| envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; |
| envp[2] = NULL; |
| |
| call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); |
| out_free: |
| kfree(agentbuf); |
| kfree(pathbuf); |
| } |
| |
| /* |
| * cgroup_rename - Only allow simple rename of directories in place. |
| */ |
| static int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent, |
| const char *new_name_str) |
| { |
| struct cgroup *cgrp = kn->priv; |
| int ret; |
| |
| /* do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable */ |
| if (strchr(new_name_str, '\n')) |
| return -EINVAL; |
| |
| if (kernfs_type(kn) != KERNFS_DIR) |
| return -ENOTDIR; |
| if (kn->parent != new_parent) |
| return -EIO; |
| |
| /* |
| * We're gonna grab cgroup_mutex which nests outside kernfs |
| * active_ref. kernfs_rename() doesn't require active_ref |
| * protection. Break them before grabbing cgroup_mutex. |
| */ |
| kernfs_break_active_protection(new_parent); |
| kernfs_break_active_protection(kn); |
| |
| mutex_lock(&cgroup_mutex); |
| |
| ret = kernfs_rename(kn, new_parent, new_name_str); |
| if (!ret) |
| TRACE_CGROUP_PATH(rename, cgrp); |
| |
| mutex_unlock(&cgroup_mutex); |
| |
| kernfs_unbreak_active_protection(kn); |
| kernfs_unbreak_active_protection(new_parent); |
| return ret; |
| } |
| |
| static int cgroup1_show_options(struct seq_file *seq, struct kernfs_root *kf_root) |
| { |
| struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
| struct cgroup_subsys *ss; |
| int ssid; |
| |
| for_each_subsys(ss, ssid) |
| if (root->subsys_mask & (1 << ssid)) |
| seq_show_option(seq, ss->legacy_name, NULL); |
| if (root->flags & CGRP_ROOT_NOPREFIX) |
| seq_puts(seq, ",noprefix"); |
| if (root->flags & CGRP_ROOT_XATTR) |
| seq_puts(seq, ",xattr"); |
| if (root->flags & CGRP_ROOT_CPUSET_V2_MODE) |
| seq_puts(seq, ",cpuset_v2_mode"); |
| if (root->flags & CGRP_ROOT_FAVOR_DYNMODS) |
| seq_puts(seq, ",favordynmods"); |
| |
| spin_lock(&release_agent_path_lock); |
| if (strlen(root->release_agent_path)) |
| seq_show_option(seq, "release_agent", |
| root->release_agent_path); |
| spin_unlock(&release_agent_path_lock); |
| |
| if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags)) |
| seq_puts(seq, ",clone_children"); |
| if (strlen(root->name)) |
| seq_show_option(seq, "name", root->name); |
| return 0; |
| } |
| |
| enum cgroup1_param { |
| Opt_all, |
| Opt_clone_children, |
| Opt_cpuset_v2_mode, |
| Opt_name, |
| Opt_none, |
| Opt_noprefix, |
| Opt_release_agent, |
| Opt_xattr, |
| Opt_favordynmods, |
| Opt_nofavordynmods, |
| }; |
| |
| const struct fs_parameter_spec cgroup1_fs_parameters[] = { |
| fsparam_flag ("all", Opt_all), |
| fsparam_flag ("clone_children", Opt_clone_children), |
| fsparam_flag ("cpuset_v2_mode", Opt_cpuset_v2_mode), |
| fsparam_string("name", Opt_name), |
| fsparam_flag ("none", Opt_none), |
| fsparam_flag ("noprefix", Opt_noprefix), |
| fsparam_string("release_agent", Opt_release_agent), |
| fsparam_flag ("xattr", Opt_xattr), |
| fsparam_flag ("favordynmods", Opt_favordynmods), |
| fsparam_flag ("nofavordynmods", Opt_nofavordynmods), |
| {} |
| }; |
| |
| int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param) |
| { |
| struct cgroup_fs_context *ctx = cgroup_fc2context(fc); |
| struct cgroup_subsys *ss; |
| struct fs_parse_result result; |
| int opt, i; |
| |
| opt = fs_parse(fc, cgroup1_fs_parameters, param, &result); |
| if (opt == -ENOPARAM) { |
| int ret; |
| |
| ret = vfs_parse_fs_param_source(fc, param); |
| if (ret != -ENOPARAM) |
| return ret; |
| for_each_subsys(ss, i) { |
| if (strcmp(param->key, ss->legacy_name)) |
| continue; |
| if (!cgroup_ssid_enabled(i) || cgroup1_ssid_disabled(i)) |
| return invalfc(fc, "Disabled controller '%s'", |
| param->key); |
| ctx->subsys_mask |= (1 << i); |
| return 0; |
| } |
| return invalfc(fc, "Unknown subsys name '%s'", param->key); |
| } |
| if (opt < 0) |
| return opt; |
| |
| switch (opt) { |
| case Opt_none: |
| /* Explicitly have no subsystems */ |
| ctx->none = true; |
| break; |
| case Opt_all: |
| ctx->all_ss = true; |
| break; |
| case Opt_noprefix: |
| ctx->flags |= CGRP_ROOT_NOPREFIX; |
| break; |
| case Opt_clone_children: |
| ctx->cpuset_clone_children = true; |
| break; |
| case Opt_cpuset_v2_mode: |
| ctx->flags |= CGRP_ROOT_CPUSET_V2_MODE; |
| break; |
| case Opt_xattr: |
| ctx->flags |= CGRP_ROOT_XATTR; |
| break; |
| case Opt_favordynmods: |
| ctx->flags |= CGRP_ROOT_FAVOR_DYNMODS; |
| break; |
| case Opt_nofavordynmods: |
| ctx->flags &= ~CGRP_ROOT_FAVOR_DYNMODS; |
| break; |
| case Opt_release_agent: |
| /* Specifying two release agents is forbidden */ |
| if (ctx->release_agent) |
| return invalfc(fc, "release_agent respecified"); |
| /* |
| * Release agent gets called with all capabilities, |
| * require capabilities to set release agent. |
| */ |
| if ((fc->user_ns != &init_user_ns) || !capable(CAP_SYS_ADMIN)) |
| return invalfc(fc, "Setting release_agent not allowed"); |
| ctx->release_agent = param->string; |
| param->string = NULL; |
| break; |
| case Opt_name: |
| /* blocked by boot param? */ |
| if (cgroup_no_v1_named) |
| return -ENOENT; |
| /* Can't specify an empty name */ |
| if (!param->size) |
| return invalfc(fc, "Empty name"); |
| if (param->size > MAX_CGROUP_ROOT_NAMELEN - 1) |
| return invalfc(fc, "Name too long"); |
| /* Must match [\w.-]+ */ |
| for (i = 0; i < param->size; i++) { |
| char c = param->string[i]; |
| if (isalnum(c)) |
| continue; |
| if ((c == '.') || (c == '-') || (c == '_')) |
| continue; |
| return invalfc(fc, "Invalid name"); |
| } |
| /* Specifying two names is forbidden */ |
| if (ctx->name) |
| return invalfc(fc, "name respecified"); |
| ctx->name = param->string; |
| param->string = NULL; |
| break; |
| } |
| return 0; |
| } |
| |
| static int check_cgroupfs_options(struct fs_context *fc) |
| { |
| struct cgroup_fs_context *ctx = cgroup_fc2context(fc); |
| u16 mask = U16_MAX; |
| u16 enabled = 0; |
| struct cgroup_subsys *ss; |
| int i; |
| |
| #ifdef CONFIG_CPUSETS |
| mask = ~((u16)1 << cpuset_cgrp_id); |
| #endif |
| for_each_subsys(ss, i) |
| if (cgroup_ssid_enabled(i) && !cgroup1_ssid_disabled(i)) |
| enabled |= 1 << i; |
| |
| ctx->subsys_mask &= enabled; |
| |
| /* |
| * In absence of 'none', 'name=' and subsystem name options, |
| * let's default to 'all'. |
| */ |
| if (!ctx->subsys_mask && !ctx->none && !ctx->name) |
| ctx->all_ss = true; |
| |
| if (ctx->all_ss) { |
| /* Mutually exclusive option 'all' + subsystem name */ |
| if (ctx->subsys_mask) |
| return invalfc(fc, "subsys name conflicts with all"); |
| /* 'all' => select all the subsystems */ |
| ctx->subsys_mask = enabled; |
| } |
| |
| /* |
| * We either have to specify by name or by subsystems. (So all |
| * empty hierarchies must have a name). |
| */ |
| if (!ctx->subsys_mask && !ctx->name) |
| return invalfc(fc, "Need name or subsystem set"); |
| |
| /* |
| * Option noprefix was introduced just for backward compatibility |
| * with the old cpuset, so we allow noprefix only if mounting just |
| * the cpuset subsystem. |
| */ |
| if ((ctx->flags & CGRP_ROOT_NOPREFIX) && (ctx->subsys_mask & mask)) |
| return invalfc(fc, "noprefix used incorrectly"); |
| |
| /* Can't specify "none" and some subsystems */ |
| if (ctx->subsys_mask && ctx->none) |
| return invalfc(fc, "none used incorrectly"); |
| |
| return 0; |
| } |
| |
| int cgroup1_reconfigure(struct fs_context *fc) |
| { |
| struct cgroup_fs_context *ctx = cgroup_fc2context(fc); |
| struct kernfs_root *kf_root = kernfs_root_from_sb(fc->root->d_sb); |
| struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
| int ret = 0; |
| u16 added_mask, removed_mask; |
| |
| cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp); |
| |
| /* See what subsystems are wanted */ |
| ret = check_cgroupfs_options(fc); |
| if (ret) |
| goto out_unlock; |
| |
| if (ctx->subsys_mask != root->subsys_mask || ctx->release_agent) |
| pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n", |
| task_tgid_nr(current), current->comm); |
| |
| added_mask = ctx->subsys_mask & ~root->subsys_mask; |
| removed_mask = root->subsys_mask & ~ctx->subsys_mask; |
| |
| /* Don't allow flags or name to change at remount */ |
| if ((ctx->flags ^ root->flags) || |
| (ctx->name && strcmp(ctx->name, root->name))) { |
| errorfc(fc, "option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"", |
| ctx->flags, ctx->name ?: "", root->flags, root->name); |
| ret = -EINVAL; |
| goto out_unlock; |
| } |
| |
| /* remounting is not allowed for populated hierarchies */ |
| if (!list_empty(&root->cgrp.self.children)) { |
| ret = -EBUSY; |
| goto out_unlock; |
| } |
| |
| ret = rebind_subsystems(root, added_mask); |
| if (ret) |
| goto out_unlock; |
| |
| WARN_ON(rebind_subsystems(&cgrp_dfl_root, removed_mask)); |
| |
| if (ctx->release_agent) { |
| spin_lock(&release_agent_path_lock); |
| strcpy(root->release_agent_path, ctx->release_agent); |
| spin_unlock(&release_agent_path_lock); |
| } |
| |
| trace_cgroup_remount(root); |
| |
| out_unlock: |
| mutex_unlock(&cgroup_mutex); |
| return ret; |
| } |
| |
| struct kernfs_syscall_ops cgroup1_kf_syscall_ops = { |
| .rename = cgroup1_rename, |
| .show_options = cgroup1_show_options, |
| .mkdir = cgroup_mkdir, |
| .rmdir = cgroup_rmdir, |
| .show_path = cgroup_show_path, |
| }; |
| |
| /* |
| * The guts of cgroup1 mount - find or create cgroup_root to use. |
| * Called with cgroup_mutex held; returns 0 on success, -E... on |
| * error and positive - in case when the candidate is busy dying. |
| * On success it stashes a reference to cgroup_root into given |
| * cgroup_fs_context; that reference is *NOT* counting towards the |
| * cgroup_root refcount. |
| */ |
| static int cgroup1_root_to_use(struct fs_context *fc) |
| { |
| struct cgroup_fs_context *ctx = cgroup_fc2context(fc); |
| struct cgroup_root *root; |
| struct cgroup_subsys *ss; |
| int i, ret; |
| |
| /* First find the desired set of subsystems */ |
| ret = check_cgroupfs_options(fc); |
| if (ret) |
| return ret; |
| |
| /* |
| * Destruction of cgroup root is asynchronous, so subsystems may |
| * still be dying after the previous unmount. Let's drain the |
| * dying subsystems. We just need to ensure that the ones |
| * unmounted previously finish dying and don't care about new ones |
| * starting. Testing ref liveliness is good enough. |
| */ |
| for_each_subsys(ss, i) { |
| if (!(ctx->subsys_mask & (1 << i)) || |
| ss->root == &cgrp_dfl_root) |
| continue; |
| |
| if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) |
| return 1; /* restart */ |
| cgroup_put(&ss->root->cgrp); |
| } |
| |
| for_each_root(root) { |
| bool name_match = false; |
| |
| if (root == &cgrp_dfl_root) |
| continue; |
| |
| /* |
| * If we asked for a name then it must match. Also, if |
| * name matches but sybsys_mask doesn't, we should fail. |
| * Remember whether name matched. |
| */ |
| if (ctx->name) { |
| if (strcmp(ctx->name, root->name)) |
| continue; |
| name_match = true; |
| } |
| |
| /* |
| * If we asked for subsystems (or explicitly for no |
| * subsystems) then they must match. |
| */ |
| if ((ctx->subsys_mask || ctx->none) && |
| (ctx->subsys_mask != root->subsys_mask)) { |
| if (!name_match) |
| continue; |
| return -EBUSY; |
| } |
| |
| if (root->flags ^ ctx->flags) |
| pr_warn("new mount options do not match the existing superblock, will be ignored\n"); |
| |
| ctx->root = root; |
| return 0; |
| } |
| |
| /* |
| * No such thing, create a new one. name= matching without subsys |
| * specification is allowed for already existing hierarchies but we |
| * can't create new one without subsys specification. |
| */ |
| if (!ctx->subsys_mask && !ctx->none) |
| return invalfc(fc, "No subsys list or none specified"); |
| |
| /* Hierarchies may only be created in the initial cgroup namespace. */ |
| if (ctx->ns != &init_cgroup_ns) |
| return -EPERM; |
| |
| root = kzalloc(sizeof(*root), GFP_KERNEL); |
| if (!root) |
| return -ENOMEM; |
| |
| ctx->root = root; |
| init_cgroup_root(ctx); |
| |
| ret = cgroup_setup_root(root, ctx->subsys_mask); |
| if (!ret) |
| cgroup_favor_dynmods(root, ctx->flags & CGRP_ROOT_FAVOR_DYNMODS); |
| else |
| cgroup_free_root(root); |
| |
| return ret; |
| } |
| |
| int cgroup1_get_tree(struct fs_context *fc) |
| { |
| struct cgroup_fs_context *ctx = cgroup_fc2context(fc); |
| int ret; |
| |
| /* Check if the caller has permission to mount. */ |
| if (!ns_capable(ctx->ns->user_ns, CAP_SYS_ADMIN)) |
| return -EPERM; |
| |
| cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp); |
| |
| ret = cgroup1_root_to_use(fc); |
| if (!ret && !percpu_ref_tryget_live(&ctx->root->cgrp.self.refcnt)) |
| ret = 1; /* restart */ |
| |
| mutex_unlock(&cgroup_mutex); |
| |
| if (!ret) |
| ret = cgroup_do_get_tree(fc); |
| |
| if (!ret && percpu_ref_is_dying(&ctx->root->cgrp.self.refcnt)) { |
| fc_drop_locked(fc); |
| ret = 1; |
| } |
| |
| if (unlikely(ret > 0)) { |
| msleep(10); |
| return restart_syscall(); |
| } |
| return ret; |
| } |
| |
| static int __init cgroup1_wq_init(void) |
| { |
| /* |
| * Used to destroy pidlists and separate to serve as flush domain. |
| * Cap @max_active to 1 too. |
| */ |
| cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy", |
| 0, 1); |
| BUG_ON(!cgroup_pidlist_destroy_wq); |
| return 0; |
| } |
| core_initcall(cgroup1_wq_init); |
| |
| static int __init cgroup_no_v1(char *str) |
| { |
| struct cgroup_subsys *ss; |
| char *token; |
| int i; |
| |
| while ((token = strsep(&str, ",")) != NULL) { |
| if (!*token) |
| continue; |
| |
| if (!strcmp(token, "all")) { |
| cgroup_no_v1_mask = U16_MAX; |
| continue; |
| } |
| |
| if (!strcmp(token, "named")) { |
| cgroup_no_v1_named = true; |
| continue; |
| } |
| |
| for_each_subsys(ss, i) { |
| if (strcmp(token, ss->name) && |
| strcmp(token, ss->legacy_name)) |
| continue; |
| |
| cgroup_no_v1_mask |= 1 << i; |
| } |
| } |
| return 1; |
| } |
| __setup("cgroup_no_v1=", cgroup_no_v1); |