Commit d08311dd authored by Eric W. Biederman's avatar Eric W. Biederman

cgroupns: Add a limit on the number of cgroup namespaces

Acked-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
parent aba35661
......@@ -621,6 +621,7 @@ struct cgroup_namespace {
atomic_t count;
struct ns_common ns;
struct user_namespace *user_ns;
struct ucounts *ucounts;
struct css_set *root_cset;
};
......
......@@ -29,6 +29,7 @@ enum ucount_type {
UCOUNT_PID_NAMESPACES,
UCOUNT_UTS_NAMESPACES,
UCOUNT_IPC_NAMESPACES,
UCOUNT_CGROUP_NAMESPACES,
UCOUNT_COUNTS,
};
......
......@@ -6295,6 +6295,16 @@ void cgroup_sk_free(struct sock_cgroup_data *skcd)
/* cgroup namespaces */
static struct ucounts *inc_cgroup_namespaces(struct user_namespace *ns)
{
return inc_ucount(ns, current_euid(), UCOUNT_CGROUP_NAMESPACES);
}
static void dec_cgroup_namespaces(struct ucounts *ucounts)
{
dec_ucount(ucounts, UCOUNT_CGROUP_NAMESPACES);
}
static struct cgroup_namespace *alloc_cgroup_ns(void)
{
struct cgroup_namespace *new_ns;
......@@ -6316,6 +6326,7 @@ static struct cgroup_namespace *alloc_cgroup_ns(void)
void free_cgroup_ns(struct cgroup_namespace *ns)
{
put_css_set(ns->root_cset);
dec_cgroup_namespaces(ns->ucounts);
put_user_ns(ns->user_ns);
ns_free_inum(&ns->ns);
kfree(ns);
......@@ -6327,6 +6338,7 @@ struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
struct cgroup_namespace *old_ns)
{
struct cgroup_namespace *new_ns;
struct ucounts *ucounts;
struct css_set *cset;
BUG_ON(!old_ns);
......@@ -6340,6 +6352,10 @@ struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
if (!ns_capable(user_ns, CAP_SYS_ADMIN))
return ERR_PTR(-EPERM);
ucounts = inc_cgroup_namespaces(user_ns);
if (!ucounts)
return ERR_PTR(-ENFILE);
/* It is not safe to take cgroup_mutex here */
spin_lock_irq(&css_set_lock);
cset = task_css_set(current);
......@@ -6349,10 +6365,12 @@ struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
new_ns = alloc_cgroup_ns();
if (IS_ERR(new_ns)) {
put_css_set(cset);
dec_cgroup_namespaces(ucounts);
return new_ns;
}
new_ns->user_ns = get_user_ns(user_ns);
new_ns->ucounts = ucounts;
new_ns->root_cset = cset;
return new_ns;
......
......@@ -71,6 +71,7 @@ static struct ctl_table user_table[] = {
UCOUNT_ENTRY("max_pid_namespaces"),
UCOUNT_ENTRY("max_uts_namespaces"),
UCOUNT_ENTRY("max_ipc_namespaces"),
UCOUNT_ENTRY("max_cgroup_namespaces"),
{ }
};
#endif /* CONFIG_SYSCTL */
......
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