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

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

include/linux/cgroup.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -621,6 +621,7 @@ struct cgroup_namespace { 
	atomic_t		count;

	atomic_t		count;

	struct ns_common	ns;

	struct ns_common	ns;

	struct user_namespace	*user_ns;

	struct user_namespace	*user_ns;

	struct ucounts		*ucounts;

	struct css_set          *root_cset;

	struct css_set          *root_cset;

};

};

include/linux/user_namespace.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -29,6 +29,7 @@ enum ucount_type { 
	UCOUNT_PID_NAMESPACES,

	UCOUNT_PID_NAMESPACES,

	UCOUNT_UTS_NAMESPACES,

	UCOUNT_UTS_NAMESPACES,

	UCOUNT_IPC_NAMESPACES,

	UCOUNT_IPC_NAMESPACES,

	UCOUNT_CGROUP_NAMESPACES,

	UCOUNT_COUNTS,

	UCOUNT_COUNTS,

};

};

kernel/cgroup.c

+18 −0
Original line number Original line Diff line number Diff line
@@ -6295,6 +6295,16 @@ void cgroup_sk_free(struct sock_cgroup_data *skcd) 




/* cgroup namespaces */

/* 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)

static struct cgroup_namespace *alloc_cgroup_ns(void)

{

{

	struct cgroup_namespace *new_ns;

	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)

void free_cgroup_ns(struct cgroup_namespace *ns)

{

{

	put_css_set(ns->root_cset);

	put_css_set(ns->root_cset);

	dec_cgroup_namespaces(ns->ucounts);

	put_user_ns(ns->user_ns);

	put_user_ns(ns->user_ns);

	ns_free_inum(&ns->ns);

	ns_free_inum(&ns->ns);

	kfree(ns);

	kfree(ns);
@@ -6327,6 +6338,7 @@ struct cgroup_namespace *copy_cgroup_ns(unsigned long flags, 
					struct cgroup_namespace *old_ns)

					struct cgroup_namespace *old_ns)

{

{

	struct cgroup_namespace *new_ns;

	struct cgroup_namespace *new_ns;

	struct ucounts *ucounts;

	struct css_set *cset;

	struct css_set *cset;





	BUG_ON(!old_ns);

	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))

	if (!ns_capable(user_ns, CAP_SYS_ADMIN))

		return ERR_PTR(-EPERM);

		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 */

	/* It is not safe to take cgroup_mutex here */

	spin_lock_irq(&css_set_lock);

	spin_lock_irq(&css_set_lock);

	cset = task_css_set(current);

	cset = task_css_set(current);
@@ -6349,10 +6365,12 @@ struct cgroup_namespace *copy_cgroup_ns(unsigned long flags, 
	new_ns = alloc_cgroup_ns();

	new_ns = alloc_cgroup_ns();

	if (IS_ERR(new_ns)) {

	if (IS_ERR(new_ns)) {

		put_css_set(cset);

		put_css_set(cset);

		dec_cgroup_namespaces(ucounts);

		return new_ns;

		return new_ns;

	}

	}





	new_ns->user_ns = get_user_ns(user_ns);

	new_ns->user_ns = get_user_ns(user_ns);

	new_ns->ucounts = ucounts;

	new_ns->root_cset = cset;

	new_ns->root_cset = cset;





	return new_ns;

	return new_ns;

kernel/ucount.c

+1 −0
Original line number Original line Diff line number Diff line
@@ -71,6 +71,7 @@ static struct ctl_table user_table[] = { 
	UCOUNT_ENTRY("max_pid_namespaces"),

	UCOUNT_ENTRY("max_pid_namespaces"),

	UCOUNT_ENTRY("max_uts_namespaces"),

	UCOUNT_ENTRY("max_uts_namespaces"),

	UCOUNT_ENTRY("max_ipc_namespaces"),

	UCOUNT_ENTRY("max_ipc_namespaces"),

	UCOUNT_ENTRY("max_cgroup_namespaces"),

	{ }

	{ }

};

};

#endif /* CONFIG_SYSCTL */

#endif /* CONFIG_SYSCTL */