af_iucv: Modify iucv msg target class using control msghdr

Allow 'classification' of socket data that is sent or received over
an af_iucv socket. For classification of data, the target class of an
(native) iucv message is used.

This patch provides the cmsg interface for iucv_sock_recvmsg() and
iucv_sock_sendmsg().  Applications can use the msg_control field of
struct msghdr to set or get the target class as a
"socket control message" (SCM/CMSG).

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/iucv/af_iucv.h b/include/net/iucv/af_iucv.h
index 78a7276..b57739e 100644 (file)
--- a/include/net/iucv/af_iucv.h
+++ b/include/net/iucv/af_iucv.h
@@ -79,6 +79,9 @@ struct iucv_sock {
 /* iucv socket options (SOL_IUCV) */
 #define SO_IPRMDATA_MSG        0x0080          /* send/recv IPRM_DATA msgs */
 
+/* iucv related control messages (scm) */
+#define SCM_IUCV_TRGCLS        0x0001          /* target class control message */
+
 struct iucv_sock_list {
        struct hlist_head head;
        rwlock_t          lock;

diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
index 5fc077e..47c5c8d 100644 (file)
--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -45,6 +45,15 @@ static struct proto iucv_proto = {
 static const u8 iprm_shutdown[8] =
        {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01};
 
+#define TRGCLS_SIZE    (sizeof(((struct iucv_message *)0)->class))
+
+/* macros to set/get socket control buffer at correct offset */
+#define CB_TAG(skb)    ((skb)->cb)             /* iucv message tag */
+#define CB_TAG_LEN     (sizeof(((struct iucv_message *) 0)->tag))
+#define CB_TRGCLS(skb) ((skb)->cb + CB_TAG_LEN) /* iucv msg target class */
+#define CB_TRGCLS_LEN  (TRGCLS_SIZE)
+
+
 static void iucv_sock_kill(struct sock *sk);
 static void iucv_sock_close(struct sock *sk);
 
@@ -698,6 +707,8 @@ static int iucv_sock_sendmsg(struct kiocb *iocb, struct socket *sock,
        struct iucv_sock *iucv = iucv_sk(sk);
        struct sk_buff *skb;
        struct iucv_message txmsg;
+       struct cmsghdr *cmsg;
+       int cmsg_done;
        char user_id[9];
        char appl_id[9];
        int err;
@@ -717,6 +728,48 @@ static int iucv_sock_sendmsg(struct kiocb *iocb, struct socket *sock,
        }
 
        if (sk->sk_state == IUCV_CONNECTED) {
+               /* initialize defaults */
+               cmsg_done   = 0;        /* check for duplicate headers */
+               txmsg.class = 0;
+
+               /* iterate over control messages */
+               for (cmsg = CMSG_FIRSTHDR(msg); cmsg;
+                    cmsg = CMSG_NXTHDR(msg, cmsg)) {
+
+                       if (!CMSG_OK(msg, cmsg)) {
+                               err = -EINVAL;
+                               goto out;
+                       }
+
+                       if (cmsg->cmsg_level != SOL_IUCV)
+                               continue;
+
+                       if (cmsg->cmsg_type & cmsg_done) {
+                               err = -EINVAL;
+                               goto out;
+                       }
+                       cmsg_done |= cmsg->cmsg_type;
+
+                       switch (cmsg->cmsg_type) {
+                       case SCM_IUCV_TRGCLS:
+                               if (cmsg->cmsg_len != CMSG_LEN(TRGCLS_SIZE)) {
+                                       err = -EINVAL;
+                                       goto out;
+                               }
+
+                               /* set iucv message target class */
+                               memcpy(&txmsg.class,
+                                       (void *) CMSG_DATA(cmsg), TRGCLS_SIZE);
+
+                               break;
+
+                       default:
+                               err = -EINVAL;
+                               goto out;
+                               break;
+                       }
+               }
+
                if (!(skb = sock_alloc_send_skb(sk, len,
                                                msg->msg_flags & MSG_DONTWAIT,
                                                &err)))
@@ -727,10 +780,9 @@ static int iucv_sock_sendmsg(struct kiocb *iocb, struct socket *sock,
                        goto fail;
                }
 
-               txmsg.class = 0;
-               memcpy(&txmsg.class, skb->data, skb->len >= 4 ? 4 : skb->len);
+               /* increment and save iucv message tag for msg_completion cbk */
                txmsg.tag = iucv->send_tag++;
-               memcpy(skb->cb, &txmsg.tag, 4);
+               memcpy(CB_TAG(skb), &txmsg.tag, CB_TAG_LEN);
                skb_queue_tail(&iucv->send_skb_q, skb);
 
                if (((iucv->path->flags & IUCV_IPRMDATA) & iucv->flags)
@@ -801,6 +853,10 @@ static int iucv_fragment_skb(struct sock *sk, struct sk_buff *skb, int len)
                if (!nskb)
                        return -ENOMEM;
 
+               /* copy target class to control buffer of new skb */
+               memcpy(CB_TRGCLS(nskb), CB_TRGCLS(skb), CB_TRGCLS_LEN);
+
+               /* copy data fragment */
                memcpy(nskb->data, skb->data + copied, size);
                copied += size;
                dataleft -= size;
@@ -824,6 +880,10 @@ static void iucv_process_message(struct sock *sk, struct sk_buff *skb,
 
        len = iucv_msg_length(msg);
 
+       /* store msg target class in the second 4 bytes of skb ctrl buffer */
+       /* Note: the first 4 bytes are reserved for msg tag */
+       memcpy(CB_TRGCLS(skb), &msg->class, CB_TRGCLS_LEN);
+
        /* check for special IPRM messages (e.g. iucv_sock_shutdown) */
        if ((msg->flags & IUCV_IPRMDATA) && len > 7) {
                if (memcmp(msg->rmmsg, iprm_shutdown, 8) == 0) {
@@ -915,6 +975,17 @@ static int iucv_sock_recvmsg(struct kiocb *iocb, struct socket *sock,
 
        len -= copied;
 
+       /* create control message to store iucv msg target class:
+        * get the trgcls from the control buffer of the skb due to
+        * fragmentation of original iucv message. */
+       err = put_cmsg(msg, SOL_IUCV, SCM_IUCV_TRGCLS,
+                       CB_TRGCLS_LEN, CB_TRGCLS(skb));
+       if (err) {
+               if (!(flags & MSG_PEEK))
+                       skb_queue_head(&sk->sk_receive_queue, skb);
+               return err;
+       }
+
        /* Mark read part of skb as used */
        if (!(flags & MSG_PEEK)) {
                skb_pull(skb, copied);
@@ -1316,7 +1387,7 @@ static void iucv_callback_txdone(struct iucv_path *path,
                spin_lock_irqsave(&list->lock, flags);
 
                while (list_skb != (struct sk_buff *)list) {
-                       if (!memcmp(&msg->tag, list_skb->cb, 4)) {
+                       if (!memcmp(&msg->tag, CB_TAG(list_skb), CB_TAG_LEN)) {
                                this = list_skb;
                                break;
                        }