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/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
index 5fc077e..47c5c8d 100644
--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -45,6 +45,15 @@
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 @@
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 @@
}
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 @@
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 @@
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 @@
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 @@
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 @@
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;
}