netns: send uevent messages

[sfrench/cifs-2.6.git] / lib / kobject_uevent.c

diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c
index 54cfbaeb3a4ebdc3bc304441a934435453ef4b1e..fa10ad8e9b17494814b976eaf9689b16a8c561bd 100644 (file)
--- a/lib/kobject_uevent.c
+++ b/lib/kobject_uevent.c
@@ -25,6 +25,7 @@
 #include <linux/uuid.h>
 #include <linux/ctype.h>
 #include <net/sock.h>
+#include <net/netlink.h>
 #include <net/net_namespace.h>
 
 
@@ -604,12 +605,88 @@ int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
 EXPORT_SYMBOL_GPL(add_uevent_var);
 
 #if defined(CONFIG_NET)
+static int uevent_net_broadcast(struct sock *usk, struct sk_buff *skb,
+                               struct netlink_ext_ack *extack)
+{
+       /* u64 to chars: 2^64 - 1 = 21 chars */
+       char buf[sizeof("SEQNUM=") + 21];
+       struct sk_buff *skbc;
+       int ret;
+
+       /* bump and prepare sequence number */
+       ret = snprintf(buf, sizeof(buf), "SEQNUM=%llu", ++uevent_seqnum);
+       if (ret < 0 || (size_t)ret >= sizeof(buf))
+               return -ENOMEM;
+       ret++;
+
+       /* verify message does not overflow */
+       if ((skb->len + ret) > UEVENT_BUFFER_SIZE) {
+               NL_SET_ERR_MSG(extack, "uevent message too big");
+               return -EINVAL;
+       }
+
+       /* copy skb and extend to accommodate sequence number */
+       skbc = skb_copy_expand(skb, 0, ret, GFP_KERNEL);
+       if (!skbc)
+               return -ENOMEM;
+
+       /* append sequence number */
+       skb_put_data(skbc, buf, ret);
+
+       /* remove msg header */
+       skb_pull(skbc, NLMSG_HDRLEN);
+
+       /* set portid 0 to inform userspace message comes from kernel */
+       NETLINK_CB(skbc).portid = 0;
+       NETLINK_CB(skbc).dst_group = 1;
+
+       ret = netlink_broadcast(usk, skbc, 0, 1, GFP_KERNEL);
+       /* ENOBUFS should be handled in userspace */
+       if (ret == -ENOBUFS || ret == -ESRCH)
+               ret = 0;
+
+       return ret;
+}
+
+static int uevent_net_rcv_skb(struct sk_buff *skb, struct nlmsghdr *nlh,
+                             struct netlink_ext_ack *extack)
+{
+       struct net *net;
+       int ret;
+
+       if (!nlmsg_data(nlh))
+               return -EINVAL;
+
+       /*
+        * Verify that we are allowed to send messages to the target
+        * network namespace. The caller must have CAP_SYS_ADMIN in the
+        * owning user namespace of the target network namespace.
+        */
+       net = sock_net(NETLINK_CB(skb).sk);
+       if (!netlink_ns_capable(skb, net->user_ns, CAP_SYS_ADMIN)) {
+               NL_SET_ERR_MSG(extack, "missing CAP_SYS_ADMIN capability");
+               return -EPERM;
+       }
+
+       mutex_lock(&uevent_sock_mutex);
+       ret = uevent_net_broadcast(net->uevent_sock->sk, skb, extack);
+       mutex_unlock(&uevent_sock_mutex);
+
+       return ret;
+}
+
+static void uevent_net_rcv(struct sk_buff *skb)
+{
+       netlink_rcv_skb(skb, &uevent_net_rcv_skb);
+}
+
 static int uevent_net_init(struct net *net)
 {
        struct uevent_sock *ue_sk;
        struct netlink_kernel_cfg cfg = {
                .groups = 1,
-               .flags  = NL_CFG_F_NONROOT_RECV,
+               .input = uevent_net_rcv,
+               .flags  = NL_CFG_F_NONROOT_RECV
        };
 
        ue_sk = kzalloc(sizeof(*ue_sk), GFP_KERNEL);