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authorEric W. Biederman <ebiederm@xmission.com>2016-08-08 14:08:36 -0500
committerEric W. Biederman <ebiederm@xmission.com>2016-08-08 14:42:01 -0500
commitf333c700c6100b53050980986be922bb21466e29 (patch)
tree60554e8ad7eeda0cac508cade356a1358171df22 /kernel
parent25f9c0817c535a728c1088542230fa327c577c9e (diff)
downloadlinux-f333c700c6100b53050980986be922bb21466e29.tar.bz2
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/pid_namespace.c25
-rw-r--r--kernel/ucount.c1
2 files changed, 22 insertions, 4 deletions
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index a65ba137fd15..30a7f3351932 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -79,23 +79,36 @@ static void proc_cleanup_work(struct work_struct *work)
/* 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 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
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 @@ out_free_map:
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 @@ static void destroy_pid_namespace(struct pid_namespace *ns)
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);
}
diff --git a/kernel/ucount.c b/kernel/ucount.c
index 0f9ab3b26185..66eca94e4ada 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -68,6 +68,7 @@ static int int_max = INT_MAX;
}
static struct ctl_table user_table[] = {
UCOUNT_ENTRY("max_user_namespaces"),
+ UCOUNT_ENTRY("max_pid_namespaces"),
{ }
};
#endif /* CONFIG_SYSCTL */