summaryrefslogtreecommitdiff
path: root/kernel/cgroup.c
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2016-03-21 10:05:13 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-03-21 10:05:13 -0700
commit5518f66b5a64b76fd602a7baf60590cd838a2ca0 (patch)
treedfde2fa8642a7a8cb86c592ce0e155bf13b2bbd2 /kernel/cgroup.c
parent643ad15d47410d37d43daf3ef1c8ac52c281efa5 (diff)
parentfa5ff8a1c43fc7b78353059899edf3cbedf54e9f (diff)
downloadlinux-sh-5518f66b5a64b76fd602a7baf60590cd838a2ca0.tar.gz
Merge branch 'for-4.6-ns' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup namespace support from Tejun Heo: "These are changes to implement namespace support for cgroup which has been pending for quite some time now. It is very straight-forward and only affects what part of cgroup hierarchies are visible. After unsharing, mounting a cgroup fs will be scoped to the cgroups the task belonged to at the time of unsharing and the cgroup paths exposed to userland would be adjusted accordingly" * 'for-4.6-ns' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: fix and restructure error handling in copy_cgroup_ns() cgroup: fix alloc_cgroup_ns() error handling in copy_cgroup_ns() Add FS_USERNS_FLAG to cgroup fs cgroup: Add documentation for cgroup namespaces cgroup: mount cgroupns-root when inside non-init cgroupns kernfs: define kernfs_node_dentry cgroup: cgroup namespace setns support cgroup: introduce cgroup namespaces sched: new clone flag CLONE_NEWCGROUP for cgroup namespace kernfs: Add API to generate relative kernfs path
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c229
1 files changed, 225 insertions, 4 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 3fe02c152799..671dc05c0b0f 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -59,6 +59,9 @@
#include <linux/delay.h>
#include <linux/atomic.h>
#include <linux/cpuset.h>
+#include <linux/proc_ns.h>
+#include <linux/nsproxy.h>
+#include <linux/proc_ns.h>
#include <net/sock.h>
/*
@@ -215,6 +218,15 @@ static u16 have_fork_callback __read_mostly;
static u16 have_exit_callback __read_mostly;
static u16 have_free_callback __read_mostly;
+/* cgroup namespace for init task */
+struct cgroup_namespace init_cgroup_ns = {
+ .count = { .counter = 2, },
+ .user_ns = &init_user_ns,
+ .ns.ops = &cgroupns_operations,
+ .ns.inum = PROC_CGROUP_INIT_INO,
+ .root_cset = &init_css_set,
+};
+
/* Ditto for the can_fork callback. */
static u16 have_canfork_callback __read_mostly;
@@ -2002,6 +2014,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
{
bool is_v2 = fs_type == &cgroup2_fs_type;
struct super_block *pinned_sb = NULL;
+ struct cgroup_namespace *ns = current->nsproxy->cgroup_ns;
struct cgroup_subsys *ss;
struct cgroup_root *root;
struct cgroup_sb_opts opts;
@@ -2010,6 +2023,14 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
int i;
bool new_sb;
+ get_cgroup_ns(ns);
+
+ /* Check if the caller has permission to mount. */
+ if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN)) {
+ put_cgroup_ns(ns);
+ return ERR_PTR(-EPERM);
+ }
+
/*
* The first time anyone tries to mount a cgroup, enable the list
* linking each css_set to its tasks and fix up all existing tasks.
@@ -2020,6 +2041,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
if (is_v2) {
if (data) {
pr_err("cgroup2: unknown option \"%s\"\n", (char *)data);
+ put_cgroup_ns(ns);
return ERR_PTR(-EINVAL);
}
cgrp_dfl_visible = true;
@@ -2125,6 +2147,16 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
goto out_unlock;
}
+ /*
+ * We know this subsystem has not yet been bound. Users in a non-init
+ * user namespace may only mount hierarchies with no bound subsystems,
+ * i.e. 'none,name=user1'
+ */
+ if (!opts.none && !capable(CAP_SYS_ADMIN)) {
+ ret = -EPERM;
+ goto out_unlock;
+ }
+
root = kzalloc(sizeof(*root), GFP_KERNEL);
if (!root) {
ret = -ENOMEM;
@@ -2143,12 +2175,37 @@ out_free:
kfree(opts.release_agent);
kfree(opts.name);
- if (ret)
+ if (ret) {
+ put_cgroup_ns(ns);
return ERR_PTR(ret);
+ }
out_mount:
dentry = kernfs_mount(fs_type, flags, root->kf_root,
is_v2 ? CGROUP2_SUPER_MAGIC : CGROUP_SUPER_MAGIC,
&new_sb);
+
+ /*
+ * In non-init cgroup namespace, instead of root cgroup's
+ * dentry, we return the dentry corresponding to the
+ * cgroupns->root_cgrp.
+ */
+ if (!IS_ERR(dentry) && ns != &init_cgroup_ns) {
+ struct dentry *nsdentry;
+ struct cgroup *cgrp;
+
+ mutex_lock(&cgroup_mutex);
+ spin_lock_bh(&css_set_lock);
+
+ cgrp = cset_cgroup_from_root(ns->root_cset, root);
+
+ spin_unlock_bh(&css_set_lock);
+ mutex_unlock(&cgroup_mutex);
+
+ nsdentry = kernfs_node_dentry(cgrp->kn, dentry->d_sb);
+ dput(dentry);
+ dentry = nsdentry;
+ }
+
if (IS_ERR(dentry) || !new_sb)
cgroup_put(&root->cgrp);
@@ -2161,6 +2218,7 @@ out_mount:
deactivate_super(pinned_sb);
}
+ put_cgroup_ns(ns);
return dentry;
}
@@ -2189,14 +2247,45 @@ static struct file_system_type cgroup_fs_type = {
.name = "cgroup",
.mount = cgroup_mount,
.kill_sb = cgroup_kill_sb,
+ .fs_flags = FS_USERNS_MOUNT,
};
static struct file_system_type cgroup2_fs_type = {
.name = "cgroup2",
.mount = cgroup_mount,
.kill_sb = cgroup_kill_sb,
+ .fs_flags = FS_USERNS_MOUNT,
};
+static char *cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
+ struct cgroup_namespace *ns)
+{
+ struct cgroup *root = cset_cgroup_from_root(ns->root_cset, cgrp->root);
+ int ret;
+
+ ret = kernfs_path_from_node(cgrp->kn, root->kn, buf, buflen);
+ if (ret < 0 || ret >= buflen)
+ return NULL;
+ return buf;
+}
+
+char *cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen,
+ struct cgroup_namespace *ns)
+{
+ char *ret;
+
+ mutex_lock(&cgroup_mutex);
+ spin_lock_bh(&css_set_lock);
+
+ ret = cgroup_path_ns_locked(cgrp, buf, buflen, ns);
+
+ spin_unlock_bh(&css_set_lock);
+ mutex_unlock(&cgroup_mutex);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(cgroup_path_ns);
+
/**
* task_cgroup_path - cgroup path of a task in the first cgroup hierarchy
* @task: target task
@@ -2224,7 +2313,7 @@ char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen)
if (root) {
cgrp = task_cgroup_from_root(task, root);
- path = cgroup_path(cgrp, buf, buflen);
+ path = cgroup_path_ns_locked(cgrp, buf, buflen, &init_cgroup_ns);
} else {
/* if no hierarchy exists, everyone is in "/" */
if (strlcpy(buf, "/", buflen) < buflen)
@@ -5450,6 +5539,8 @@ int __init cgroup_init(void)
BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files));
BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files));
+ get_user_ns(init_cgroup_ns.user_ns);
+
mutex_lock(&cgroup_mutex);
/*
@@ -5601,7 +5692,8 @@ int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
* " (deleted)" is appended to the cgroup path.
*/
if (cgroup_on_dfl(cgrp) || !(tsk->flags & PF_EXITING)) {
- path = cgroup_path(cgrp, buf, PATH_MAX);
+ path = cgroup_path_ns_locked(cgrp, buf, PATH_MAX,
+ current->nsproxy->cgroup_ns);
if (!path) {
retval = -ENAMETOOLONG;
goto out_unlock;
@@ -5886,7 +5978,9 @@ static void cgroup_release_agent(struct work_struct *work)
if (!pathbuf || !agentbuf)
goto out;
- path = cgroup_path(cgrp, pathbuf, PATH_MAX);
+ spin_lock_bh(&css_set_lock);
+ path = cgroup_path_ns_locked(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns);
+ spin_unlock_bh(&css_set_lock);
if (!path)
goto out;
@@ -6098,6 +6192,133 @@ void cgroup_sk_free(struct sock_cgroup_data *skcd)
#endif /* CONFIG_SOCK_CGROUP_DATA */
+/* cgroup namespaces */
+
+static struct cgroup_namespace *alloc_cgroup_ns(void)
+{
+ struct cgroup_namespace *new_ns;
+ int ret;
+
+ new_ns = kzalloc(sizeof(struct cgroup_namespace), GFP_KERNEL);
+ if (!new_ns)
+ return ERR_PTR(-ENOMEM);
+ ret = ns_alloc_inum(&new_ns->ns);
+ if (ret) {
+ kfree(new_ns);
+ return ERR_PTR(ret);
+ }
+ atomic_set(&new_ns->count, 1);
+ new_ns->ns.ops = &cgroupns_operations;
+ return new_ns;
+}
+
+void free_cgroup_ns(struct cgroup_namespace *ns)
+{
+ put_css_set(ns->root_cset);
+ put_user_ns(ns->user_ns);
+ ns_free_inum(&ns->ns);
+ kfree(ns);
+}
+EXPORT_SYMBOL(free_cgroup_ns);
+
+struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
+ struct user_namespace *user_ns,
+ struct cgroup_namespace *old_ns)
+{
+ struct cgroup_namespace *new_ns;
+ struct css_set *cset;
+
+ BUG_ON(!old_ns);
+
+ if (!(flags & CLONE_NEWCGROUP)) {
+ get_cgroup_ns(old_ns);
+ return old_ns;
+ }
+
+ /* Allow only sysadmin to create cgroup namespace. */
+ if (!ns_capable(user_ns, CAP_SYS_ADMIN))
+ return ERR_PTR(-EPERM);
+
+ mutex_lock(&cgroup_mutex);
+ spin_lock_bh(&css_set_lock);
+
+ cset = task_css_set(current);
+ get_css_set(cset);
+
+ spin_unlock_bh(&css_set_lock);
+ mutex_unlock(&cgroup_mutex);
+
+ new_ns = alloc_cgroup_ns();
+ if (IS_ERR(new_ns)) {
+ put_css_set(cset);
+ return new_ns;
+ }
+
+ new_ns->user_ns = get_user_ns(user_ns);
+ new_ns->root_cset = cset;
+
+ return new_ns;
+}
+
+static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns)
+{
+ return container_of(ns, struct cgroup_namespace, ns);
+}
+
+static int cgroupns_install(struct nsproxy *nsproxy, struct ns_common *ns)
+{
+ struct cgroup_namespace *cgroup_ns = to_cg_ns(ns);
+
+ if (!ns_capable(current_user_ns(), CAP_SYS_ADMIN) ||
+ !ns_capable(cgroup_ns->user_ns, CAP_SYS_ADMIN))
+ return -EPERM;
+
+ /* Don't need to do anything if we are attaching to our own cgroupns. */
+ if (cgroup_ns == nsproxy->cgroup_ns)
+ return 0;
+
+ get_cgroup_ns(cgroup_ns);
+ put_cgroup_ns(nsproxy->cgroup_ns);
+ nsproxy->cgroup_ns = cgroup_ns;
+
+ return 0;
+}
+
+static struct ns_common *cgroupns_get(struct task_struct *task)
+{
+ struct cgroup_namespace *ns = NULL;
+ struct nsproxy *nsproxy;
+
+ task_lock(task);
+ nsproxy = task->nsproxy;
+ if (nsproxy) {
+ ns = nsproxy->cgroup_ns;
+ get_cgroup_ns(ns);
+ }
+ task_unlock(task);
+
+ return ns ? &ns->ns : NULL;
+}
+
+static void cgroupns_put(struct ns_common *ns)
+{
+ put_cgroup_ns(to_cg_ns(ns));
+}
+
+const struct proc_ns_operations cgroupns_operations = {
+ .name = "cgroup",
+ .type = CLONE_NEWCGROUP,
+ .get = cgroupns_get,
+ .put = cgroupns_put,
+ .install = cgroupns_install,
+};
+
+static __init int cgroup_namespaces_init(void)
+{
+ return 0;
+}
+subsys_initcall(cgroup_namespaces_init);
+
#ifdef CONFIG_CGROUP_DEBUG
static struct cgroup_subsys_state *
debug_css_alloc(struct cgroup_subsys_state *parent_css)