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Subject[PATCH v2 09/10] netns: Add a limit on the number of net namespaces
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
include/linux/user_namespace.h | 1 +
kernel/user_namespace.c | 1 +
net/core/net_namespace.c | 15 +++++++++++++++
3 files changed, 17 insertions(+)

diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 1a3a9cb93277..f86afa536baf 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -27,6 +27,7 @@ enum ucounts {
UCOUNT_PID_NAMESPACES,
UCOUNT_UTS_NAMESPACES,
UCOUNT_IPC_NAMESPACES,
+ UCOUNT_NET_NAMESPACES,
UCOUNT_CGROUP_NAMESPACES,
UCOUNT_COUNTS,
};
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 1cf074cb47e2..e326ca722ae0 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -80,6 +80,7 @@ static struct ctl_table userns_table[] = {
UCOUNT_ENTRY("max_pid_namespaces"),
UCOUNT_ENTRY("max_uts_namespaces"),
UCOUNT_ENTRY("max_ipc_namespaces"),
+ UCOUNT_ENTRY("max_net_namespaces"),
UCOUNT_ENTRY("max_cgroup_namespaces"),
{ }
};
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 2c2eb1b629b1..a489f192d619 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -266,6 +266,16 @@ struct net *get_net_ns_by_id(struct net *net, int id)
return peer;
}

+static bool inc_net_namespaces(struct user_namespace *ns)
+{
+ return inc_ucount(ns, UCOUNT_NET_NAMESPACES);
+}
+
+static void dec_net_namespaces(struct user_namespace *ns)
+{
+ dec_ucount(ns, UCOUNT_NET_NAMESPACES);
+}
+
/*
* setup_net runs the initializers for the network namespace object.
*/
@@ -276,6 +286,9 @@ static __net_init int setup_net(struct net *net, struct user_namespace *user_ns)
int error = 0;
LIST_HEAD(net_exit_list);

+ if (!inc_net_namespaces(user_ns))
+ return -ENFILE;
+
atomic_set(&net->count, 1);
atomic_set(&net->passive, 1);
net->dev_base_seq = 1;
@@ -372,6 +385,7 @@ struct net *copy_net_ns(unsigned long flags,
}
mutex_unlock(&net_mutex);
if (rv < 0) {
+ dec_net_namespaces(user_ns);
put_user_ns(user_ns);
net_drop_ns(net);
return ERR_PTR(rv);
@@ -444,6 +458,7 @@ static void cleanup_net(struct work_struct *work)
/* Finally it is safe to free my network namespace structure */
list_for_each_entry_safe(net, tmp, &net_exit_list, exit_list) {
list_del_init(&net->exit_list);
+ dec_net_namespaces(net->user_ns);
put_user_ns(net->user_ns);
net_drop_ns(net);
}
--
2.8.3
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