[NETLINK]: Convert core netlink handling to new netlink api

Fixes a theoretical memory and locking leak when the size of
the netlink header would exceed the skb tailroom.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 8b85036..0f36ddc 100644 (file)
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1147,7 +1147,7 @@ static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock,
        if (len > sk->sk_sndbuf - 32)
                goto out;
        err = -ENOBUFS;
-       skb = alloc_skb(len, GFP_KERNEL);
+       skb = nlmsg_new(len, GFP_KERNEL);
        if (skb==NULL)
                goto out;
 
@@ -1341,19 +1341,18 @@ static int netlink_dump(struct sock *sk)
        struct netlink_callback *cb;
        struct sk_buff *skb;
        struct nlmsghdr *nlh;
-       int len;
+       int len, err = -ENOBUFS;
        
        skb = sock_rmalloc(sk, NLMSG_GOODSIZE, 0, GFP_KERNEL);
        if (!skb)
-               return -ENOBUFS;
+               goto errout;
 
        spin_lock(&nlk->cb_lock);
 
        cb = nlk->cb;
        if (cb == NULL) {
-               spin_unlock(&nlk->cb_lock);
-               kfree_skb(skb);
-               return -EINVAL;
+               err = -EINVAL;
+               goto errout_skb;
        }
 
        len = cb->dump(skb, cb);
@@ -1365,8 +1364,12 @@ static int netlink_dump(struct sock *sk)
                return 0;
        }
 
-       nlh = NLMSG_NEW_ANSWER(skb, cb, NLMSG_DONE, sizeof(len), NLM_F_MULTI);
-       memcpy(NLMSG_DATA(nlh), &len, sizeof(len));
+       nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, sizeof(len), NLM_F_MULTI);
+       if (!nlh)
+               goto errout_skb;
+
+       memcpy(nlmsg_data(nlh), &len, sizeof(len));
+
        skb_queue_tail(&sk->sk_receive_queue, skb);
        sk->sk_data_ready(sk, skb->len);
 
@@ -1378,8 +1381,11 @@ static int netlink_dump(struct sock *sk)
        netlink_destroy_callback(cb);
        return 0;
 
-nlmsg_failure:
-       return -ENOBUFS;
+errout_skb:
+       spin_unlock(&nlk->cb_lock);
+       kfree_skb(skb);
+errout:
+       return err;
 }
 
 int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
@@ -1431,11 +1437,11 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err)
        int size;
 
        if (err == 0)
-               size = NLMSG_SPACE(sizeof(struct nlmsgerr));
+               size = nlmsg_total_size(sizeof(*errmsg));
        else
-               size = NLMSG_SPACE(4 + NLMSG_ALIGN(nlh->nlmsg_len));
+               size = nlmsg_total_size(sizeof(*errmsg) + nlmsg_len(nlh));
 
-       skb = alloc_skb(size, GFP_KERNEL);
+       skb = nlmsg_new(size, GFP_KERNEL);
        if (!skb) {
                struct sock *sk;
 
@@ -1451,16 +1457,15 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err)
 
        rep = __nlmsg_put(skb, NETLINK_CB(in_skb).pid, nlh->nlmsg_seq,
                          NLMSG_ERROR, sizeof(struct nlmsgerr), 0);
-       errmsg = NLMSG_DATA(rep);
+       errmsg = nlmsg_data(rep);
        errmsg->error = err;
-       memcpy(&errmsg->msg, nlh, err ? nlh->nlmsg_len : sizeof(struct nlmsghdr));
+       memcpy(&errmsg->msg, nlh, err ? nlh->nlmsg_len : sizeof(*nlh));
        netlink_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).pid, MSG_DONTWAIT);
 }
 
 static int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
                                                     struct nlmsghdr *, int *))
 {
-       unsigned int total_len;
        struct nlmsghdr *nlh;
        int err;
 
@@ -1470,8 +1475,6 @@ static int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
                if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len)
                        return 0;
 
-               total_len = min(NLMSG_ALIGN(nlh->nlmsg_len), skb->len);
-
                if (cb(skb, nlh, &err) < 0) {
                        /* Not an error, but we have to interrupt processing
                         * here. Note: that in this case we do not pull
@@ -1483,7 +1486,7 @@ static int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
                } else if (nlh->nlmsg_flags & NLM_F_ACK)
                        netlink_ack(skb, nlh, 0);
 
-               skb_pull(skb, total_len);
+               netlink_queue_skip(nlh, skb);
        }
 
        return 0;