dccp: Set per-connection CCIDs via socket options

With this patch, TX/RX CCIDs can now be changed on a per-connection
basis, which overrides the defaults set by the global sysctl variables
for TX/RX CCIDs.

To make full use of this facility, the remaining patches of this patch
set are needed, which track dependencies and activate negotiated
feature values.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 34 insertions, 0 deletions

diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index 8b63394ec24c..445884cf1c29 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -501,6 +501,36 @@ static int dccp_setsockopt_cscov(struct sock *sk, int cscov, bool rx)
         return rc;
 }
 
+static int dccp_setsockopt_ccid(struct sock *sk, int type,
+                                char __user *optval, int optlen)
+{
+        u8 *val;
+        int rc = 0;
+
+        if (optlen < 1 || optlen > DCCP_FEAT_MAX_SP_VALS)
+                return -EINVAL;
+
+        val = kmalloc(optlen, GFP_KERNEL);
+        if (val == NULL)
+                return -ENOMEM;
+
+        if (copy_from_user(val, optval, optlen)) {
+                kfree(val);
+                return -EFAULT;
+        }
+
+        lock_sock(sk);
+        if (type == DCCP_SOCKOPT_TX_CCID || type == DCCP_SOCKOPT_CCID)
+                rc = dccp_feat_register_sp(sk, DCCPF_CCID, 1, val, optlen);
+
+        if (!rc && (type == DCCP_SOCKOPT_RX_CCID || type == DCCP_SOCKOPT_CCID))
+                rc = dccp_feat_register_sp(sk, DCCPF_CCID, 0, val, optlen);
+        release_sock(sk);
+
+        kfree(val);
+        return rc;
+}
+
 static int do_dccp_setsockopt(struct sock *sk, int level, int optname,
                 char __user *optval, int optlen)
 {
@@ -515,6 +545,10 @@ static int do_dccp_setsockopt(struct sock *sk, int level, int optname,
         case DCCP_SOCKOPT_CHANGE_R:
                 DCCP_WARN("sockopt(CHANGE_L/R) is deprecated: fix your app\n");
                 return 0;
+        case DCCP_SOCKOPT_CCID:
+        case DCCP_SOCKOPT_RX_CCID:
+        case DCCP_SOCKOPT_TX_CCID:
+                return dccp_setsockopt_ccid(sk, optname, optval, optlen);
         }
 
         if (optlen < (int)sizeof(int))