// 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);
}
static bool cgroup1_subsys_absent(struct cgroup_subsys *ss)
{
/* Check also dfl_cftypes for file-less controllers, i.e. perf_event */
return ss->legacy_cftypes == NULL && ss->dfl_cftypes;
}
/**
* 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);
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);
strscpy(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) {
if (cgroup1_subsys_absent(ss))
continue;
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);
strscpy(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)
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) ||
cgroup1_subsys_absent(ss))
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) &&
!cgroup1_subsys_absent(ss))
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;
}
/**
* task_get_cgroup1 - Acquires the associated cgroup of a task within a
* specific cgroup1 hierarchy. The cgroup1 hierarchy is identified by its
* hierarchy ID.
* @tsk: The target task
* @hierarchy_id: The ID of a cgroup1 hierarchy
*
* On success, the cgroup is returned. On failure, ERR_PTR is returned.
* We limit it to cgroup1 only.
*/
struct cgroup *task_get_cgroup1(struct task_struct *tsk, int hierarchy_id)
{
struct cgroup *cgrp = ERR_PTR(-ENOENT);
struct cgroup_root *root;
unsigned long flags;
rcu_read_lock();
for_each_root(root) {
/* cgroup1 only*/
if (root == &cgrp_dfl_root)
continue;
if (root->hierarchy_id != hierarchy_id)
continue;
spin_lock_irqsave(&css_set_lock, flags);
cgrp = task_cgroup_from_root(tsk, root);
if (!cgrp || !cgroup_tryget(cgrp))
cgrp = ERR_PTR(-ENOENT);
spin_unlock_irqrestore(&css_set_lock, flags);
break;
}
rcu_read_unlock();
return cgrp;
}
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;
break;
}
}
return 1;
}
__setup("cgroup_no_v1=", cgroup_no_v1);
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