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- // 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>
- #include <trace/hooks/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;
- cgroup_lock();
- cgroup_attach_lock(true);
- 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;
- }
- cgroup_attach_unlock(true);
- cgroup_unlock();
- 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;
- cgroup_lock();
- cgroup_attach_lock(true);
- /* 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);
- cgroup_attach_unlock(true);
- cgroup_unlock();
- 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 & strip out duplicates (tgids or recycled thread PIDs) */
- sort(array, length, sizeof(pid_t), cmppid, NULL);
- 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, cgrp);
- 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) &&
- !ns_capable(tcred->user_ns, CAP_SYS_NICE))
- ret = -EACCES;
- put_cred(tcred);
- if (ret)
- goto out_finish;
- ret = cgroup_attach_task(cgrp, task, threadgroup);
- trace_android_vh_cgroup_set_task(ret, task);
- 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);
- cgroup_lock();
- ret = kernfs_rename(kn, new_parent, new_name_str);
- if (!ret)
- TRACE_CGROUP_PATH(rename, cgrp);
- cgroup_unlock();
- 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:
- cgroup_unlock();
- 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 */
- cgroup_unlock();
- 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);
|