[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>

1 files changed, 22 insertions, 19 deletions

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 8b85036ba8e3..0f36ddc0b72d 100644
--- 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;