pidns: Add a limit on the number of pid namespaces
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index a65ba13..30a7f33 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -79,23 +79,36 @@
/* MAX_PID_NS_LEVEL is needed for limiting size of 'struct pid' */
#define MAX_PID_NS_LEVEL 32
+static struct ucounts *inc_pid_namespaces(struct user_namespace *ns)
+{
+ return inc_ucount(ns, current_euid(), UCOUNT_PID_NAMESPACES);
+}
+
+static void dec_pid_namespaces(struct ucounts *ucounts)
+{
+ dec_ucount(ucounts, UCOUNT_PID_NAMESPACES);
+}
+
static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns,
struct pid_namespace *parent_pid_ns)
{
struct pid_namespace *ns;
unsigned int level = parent_pid_ns->level + 1;
+ struct ucounts *ucounts;
int i;
int err;
- if (level > MAX_PID_NS_LEVEL) {
- err = -EINVAL;
+ err = -EINVAL;
+ if (level > MAX_PID_NS_LEVEL)
goto out;
- }
+ ucounts = inc_pid_namespaces(user_ns);
+ if (!ucounts)
+ goto out;
err = -ENOMEM;
ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
if (ns == NULL)
- goto out;
+ goto out_dec;
ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
if (!ns->pidmap[0].page)
@@ -114,6 +127,7 @@
ns->level = level;
ns->parent = get_pid_ns(parent_pid_ns);
ns->user_ns = get_user_ns(user_ns);
+ ns->ucounts = ucounts;
ns->nr_hashed = PIDNS_HASH_ADDING;
INIT_WORK(&ns->proc_work, proc_cleanup_work);
@@ -129,6 +143,8 @@
kfree(ns->pidmap[0].page);
out_free:
kmem_cache_free(pid_ns_cachep, ns);
+out_dec:
+ dec_pid_namespaces(ucounts);
out:
return ERR_PTR(err);
}
@@ -146,6 +162,7 @@
ns_free_inum(&ns->ns);
for (i = 0; i < PIDMAP_ENTRIES; i++)
kfree(ns->pidmap[i].page);
+ dec_pid_namespaces(ns->ucounts);
put_user_ns(ns->user_ns);
call_rcu(&ns->rcu, delayed_free_pidns);
}