dccp qpolicy: Parameter checking of cmsg qpolicy parameters

Ensure that cmsg->cmsg_type value is valid for qpolicy 
that is currently in use.

Signed-off-by: Tomasz Grobelny <tomasz@grobelny.oswiecenia.net>
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>

3 files changed, 22 insertions, 6 deletions

diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index ce2dd6f6f34d..1585fa26488c 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -242,6 +242,7 @@ extern bool		dccp_qpolicy_full(struct sock *sk);
 extern void             dccp_qpolicy_drop(struct sock *sk, struct sk_buff *skb);
 extern struct sk_buff   *dccp_qpolicy_top(struct sock *sk);
 extern struct sk_buff   *dccp_qpolicy_pop(struct sock *sk);
+extern bool             dccp_qpolicy_param_ok(struct sock *sk, __be32 param);
 
 /*
  * TX Packet Output and TX Timers
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index b56efdd2a421..a3caa11aa836 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -735,6 +735,10 @@ static int dccp_msghdr_parse(struct msghdr *msg, struct sk_buff *skb)
                 if (cmsg->cmsg_level != SOL_DCCP)
                         continue;
 
+                if (cmsg->cmsg_type <= DCCP_SCM_QPOLICY_MAX &&
+                    !dccp_qpolicy_param_ok(skb->sk, cmsg->cmsg_type))
+                        return -EINVAL;
+
                 switch (cmsg->cmsg_type) {
                 case DCCP_SCM_PRIORITY:
                         if (cmsg->cmsg_len != CMSG_LEN(sizeof(__u32)))
diff --git a/net/dccp/qpolicy.c b/net/dccp/qpolicy.c
index 414696b0d830..27383f88c75f 100644
--- a/net/dccp/qpolicy.c
+++ b/net/dccp/qpolicy.c
@@ -73,17 +73,20 @@ static struct dccp_qpolicy_operations {
         void            (*push) (struct sock *sk, struct sk_buff *skb);
         bool            (*full) (struct sock *sk);
         struct sk_buff* (*top)  (struct sock *sk);
+        __be32          params;
 
 } qpol_table[DCCPQ_POLICY_MAX] = {
         [DCCPQ_POLICY_SIMPLE] = {
-                .push = qpolicy_simple_push,
-                .full = qpolicy_simple_full,
-                .top  = qpolicy_simple_top,
+                .push   = qpolicy_simple_push,
+                .full   = qpolicy_simple_full,
+                .top    = qpolicy_simple_top,
+                .params = 0,
         },
         [DCCPQ_POLICY_PRIO] = {
-                .push = qpolicy_simple_push,
-                .full = qpolicy_prio_full,
-                .top  = qpolicy_prio_best_skb,
+                .push   = qpolicy_simple_push,
+                .full   = qpolicy_prio_full,
+                .top    = qpolicy_prio_best_skb,
+                .params = DCCP_SCM_PRIORITY,
         },
 };
 
@@ -124,3 +127,11 @@ struct sk_buff *dccp_qpolicy_pop(struct sock *sk)
                 skb_unlink(skb, &sk->sk_write_queue);
         return skb;
 }
+
+bool dccp_qpolicy_param_ok(struct sock *sk, __be32 param)
+{
+        /* check if exactly one bit is set */
+        if (!param || (param & (param - 1)))
+                return false;
+        return (qpol_table[dccp_sk(sk)->dccps_qpolicy].params & param) == param;
+}