[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both

Provide AF_RXRPC sockets that can be used to talk to AFS servers, or serve
answers to AFS clients.  KerberosIV security is fully supported.  The patches
and some example test programs can be found in:

	http://people.redhat.com/~dhowells/rxrpc/

This will eventually replace the old implementation of kernel-only RxRPC
currently resident in net/rxrpc/.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 658 insertions, 0 deletions

diff --git a/net/rxrpc/ar-output.c b/net/rxrpc/ar-output.c
new file mode 100644
index 000000000000..67aa9510f09b
--- /dev/null
+++ b/net/rxrpc/ar-output.c
@@ -0,0 +1,658 @@
+/* RxRPC packet transmission
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/net.h>
+#include <linux/skbuff.h>
+#include <linux/circ_buf.h>
+#include <net/sock.h>
+#include <net/af_rxrpc.h>
+#include "ar-internal.h"
+
+int rxrpc_resend_timeout = 4;
+
+static int rxrpc_send_data(struct kiocb *iocb,
+			   struct rxrpc_sock *rx,
+			   struct rxrpc_call *call,
+			   struct msghdr *msg, size_t len);
+
+/*
+ * extract control messages from the sendmsg() control buffer
+ */
+static int rxrpc_sendmsg_cmsg(struct rxrpc_sock *rx, struct msghdr *msg,
+			      unsigned long *user_call_ID,
+			      enum rxrpc_command *command,
+			      u32 *abort_code,
+			      bool server)
+{
+	struct cmsghdr *cmsg;
+	int len;
+
+	*command = RXRPC_CMD_SEND_DATA;
+
+	if (msg->msg_controllen == 0)
+		return -EINVAL;
+
+	for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
+		if (!CMSG_OK(msg, cmsg))
+			return -EINVAL;
+
+		len = cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr));
+		_debug("CMSG %d, %d, %d",
+		       cmsg->cmsg_level, cmsg->cmsg_type, len);
+
+		if (cmsg->cmsg_level != SOL_RXRPC)
+			continue;
+
+		switch (cmsg->cmsg_type) {
+		case RXRPC_USER_CALL_ID:
+			if (msg->msg_flags & MSG_CMSG_COMPAT) {
+				if (len != sizeof(u32))
+					return -EINVAL;
+				*user_call_ID = *(u32 *) CMSG_DATA(cmsg);
+			} else {
+				if (len != sizeof(unsigned long))
+					return -EINVAL;
+				*user_call_ID = *(unsigned long *)
+					CMSG_DATA(cmsg);
+			}
+			_debug("User Call ID %lx", *user_call_ID);
+			break;
+
+		case RXRPC_ABORT:
+			if (*command != RXRPC_CMD_SEND_DATA)
+				return -EINVAL;
+			*command = RXRPC_CMD_SEND_ABORT;
+			if (len != sizeof(*abort_code))
+				return -EINVAL;
+			*abort_code = *(unsigned int *) CMSG_DATA(cmsg);
+			_debug("Abort %x", *abort_code);
+			if (*abort_code == 0)
+				return -EINVAL;
+			break;
+
+		case RXRPC_ACCEPT:
+			if (*command != RXRPC_CMD_SEND_DATA)
+				return -EINVAL;
+			*command = RXRPC_CMD_ACCEPT;
+			if (len != 0)
+				return -EINVAL;
+			if (!server)
+				return -EISCONN;
+			break;
+
+		default:
+			return -EINVAL;
+		}
+	}
+
+	_leave(" = 0");
+	return 0;
+}
+
+/*
+ * abort a call, sending an ABORT packet to the peer
+ */
+static void rxrpc_send_abort(struct rxrpc_call *call, u32 abort_code)
+{
+	write_lock_bh(&call->state_lock);
+
+	if (call->state <= RXRPC_CALL_COMPLETE) {
+		call->state = RXRPC_CALL_LOCALLY_ABORTED;
+		call->abort_code = abort_code;
+		set_bit(RXRPC_CALL_ABORT, &call->events);
+		del_timer_sync(&call->resend_timer);
+		del_timer_sync(&call->ack_timer);
+		clear_bit(RXRPC_CALL_RESEND_TIMER, &call->events);
+		clear_bit(RXRPC_CALL_ACK, &call->events);
+		clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
+		schedule_work(&call->processor);
+	}
+
+	write_unlock_bh(&call->state_lock);
+}
+
+/*
+ * send a message forming part of a client call through an RxRPC socket
+ * - caller holds the socket locked
+ * - the socket may be either a client socket or a server socket
+ */
+int rxrpc_client_sendmsg(struct kiocb *iocb, struct rxrpc_sock *rx,
+			 struct rxrpc_transport *trans, struct msghdr *msg,
+			 size_t len)
+{
+	struct rxrpc_conn_bundle *bundle;
+	enum rxrpc_command cmd;
+	struct rxrpc_call *call;
+	unsigned long user_call_ID = 0;
+	struct key *key;
+	__be16 service_id;
+	u32 abort_code = 0;
+	int ret;
+
+	_enter("");
+
+	ASSERT(trans != NULL);
+
+	ret = rxrpc_sendmsg_cmsg(rx, msg, &user_call_ID, &cmd, &abort_code,
+				 false);
+	if (ret < 0)
+		return ret;
+
+	bundle = NULL;
+	if (trans) {
+		service_id = rx->service_id;
+		if (msg->msg_name) {
+			struct sockaddr_rxrpc *srx =
+				(struct sockaddr_rxrpc *) msg->msg_name;
+			service_id = htons(srx->srx_service);
+		}
+		key = rx->key;
+		if (key && !rx->key->payload.data)
+			key = NULL;
+		bundle = rxrpc_get_bundle(rx, trans, key, service_id,
+					  GFP_KERNEL);
+		if (IS_ERR(bundle))
+			return PTR_ERR(bundle);
+	}
+
+	call = rxrpc_get_client_call(rx, trans, bundle, user_call_ID,
+				     abort_code == 0, GFP_KERNEL);
+	if (trans)
+		rxrpc_put_bundle(trans, bundle);
+	if (IS_ERR(call)) {
+		_leave(" = %ld", PTR_ERR(call));
+		return PTR_ERR(call);
+	}
+
+	_debug("CALL %d USR %lx ST %d on CONN %p",
+	       call->debug_id, call->user_call_ID, call->state, call->conn);
+
+	if (call->state >= RXRPC_CALL_COMPLETE) {
+		/* it's too late for this call */
+		ret = -ESHUTDOWN;
+	} else if (cmd == RXRPC_CMD_SEND_ABORT) {
+		rxrpc_send_abort(call, abort_code);
+	} else if (cmd != RXRPC_CMD_SEND_DATA) {
+		ret = -EINVAL;
+	} else if (call->state != RXRPC_CALL_CLIENT_SEND_REQUEST) {
+		/* request phase complete for this client call */
+		ret = -EPROTO;
+	} else {
+		ret = rxrpc_send_data(iocb, rx, call, msg, len);
+	}
+
+	rxrpc_put_call(call);
+	_leave(" = %d", ret);
+	return ret;
+}
+
+/*
+ * send a message through a server socket
+ * - caller holds the socket locked
+ */
+int rxrpc_server_sendmsg(struct kiocb *iocb, struct rxrpc_sock *rx,
+			 struct msghdr *msg, size_t len)
+{
+	enum rxrpc_command cmd;
+	struct rxrpc_call *call;
+	unsigned long user_call_ID = 0;
+	u32 abort_code = 0;
+	int ret;
+
+	_enter("");
+
+	ret = rxrpc_sendmsg_cmsg(rx, msg, &user_call_ID, &cmd, &abort_code,
+				 true);
+	if (ret < 0)
+		return ret;
+
+	if (cmd == RXRPC_CMD_ACCEPT)
+		return rxrpc_accept_call(rx, user_call_ID);
+
+	call = rxrpc_find_server_call(rx, user_call_ID);
+	if (!call)
+		return -EBADSLT;
+	if (call->state >= RXRPC_CALL_COMPLETE) {
+		ret = -ESHUTDOWN;
+		goto out;
+	}
+
+	switch (cmd) {
+	case RXRPC_CMD_SEND_DATA:
+		if (call->state != RXRPC_CALL_CLIENT_SEND_REQUEST &&
+		    call->state != RXRPC_CALL_SERVER_ACK_REQUEST &&
+		    call->state != RXRPC_CALL_SERVER_SEND_REPLY) {
+			/* Tx phase not yet begun for this call */
+			ret = -EPROTO;
+			break;
+		}
+
+		ret = rxrpc_send_data(iocb, rx, call, msg, len);
+		break;
+
+	case RXRPC_CMD_SEND_ABORT:
+		rxrpc_send_abort(call, abort_code);
+		break;
+	default:
+		BUG();
+	}
+
+	out:
+	rxrpc_put_call(call);
+	_leave(" = %d", ret);
+	return ret;
+}
+
+/*
+ * send a packet through the transport endpoint
+ */
+int rxrpc_send_packet(struct rxrpc_transport *trans, struct sk_buff *skb)
+{
+	struct kvec iov[1];
+	struct msghdr msg;
+	int ret, opt;
+
+	_enter(",{%d}", skb->len);
+
+	iov[0].iov_base = skb->head;
+	iov[0].iov_len = skb->len;
+
+	msg.msg_name = &trans->peer->srx.transport.sin;
+	msg.msg_namelen = sizeof(trans->peer->srx.transport.sin);
+	msg.msg_control = NULL;
+	msg.msg_controllen = 0;
+	msg.msg_flags = 0;
+
+	/* send the packet with the don't fragment bit set if we currently
+	 * think it's small enough */
+	if (skb->len - sizeof(struct rxrpc_header) < trans->peer->maxdata) {
+		down_read(&trans->local->defrag_sem);
+		/* send the packet by UDP
+		 * - returns -EMSGSIZE if UDP would have to fragment the packet
+		 *   to go out of the interface
+		 *   - in which case, we'll have processed the ICMP error
+		 *     message and update the peer record
+		 */
+		ret = kernel_sendmsg(trans->local->socket, &msg, iov, 1,
+				     iov[0].iov_len);
+
+		up_read(&trans->local->defrag_sem);
+		if (ret == -EMSGSIZE)
+			goto send_fragmentable;
+
+		_leave(" = %d [%u]", ret, trans->peer->maxdata);
+		return ret;
+	}
+
+send_fragmentable:
+	/* attempt to send this message with fragmentation enabled */
+	_debug("send fragment");
+
+	down_write(&trans->local->defrag_sem);
+	opt = IP_PMTUDISC_DONT;
+	ret = kernel_setsockopt(trans->local->socket, SOL_IP, IP_MTU_DISCOVER,
+				(char *) &opt, sizeof(opt));
+	if (ret == 0) {
+		ret = kernel_sendmsg(trans->local->socket, &msg, iov, 1,
+				     iov[0].iov_len);
+
+		opt = IP_PMTUDISC_DO;
+		kernel_setsockopt(trans->local->socket, SOL_IP,
+				  IP_MTU_DISCOVER, (char *) &opt, sizeof(opt));
+	}
+
+	up_write(&trans->local->defrag_sem);
+	_leave(" = %d [frag %u]", ret, trans->peer->maxdata);
+	return ret;
+}
+
+/*
+ * wait for space to appear in the transmit/ACK window
+ * - caller holds the socket locked
+ */
+static int rxrpc_wait_for_tx_window(struct rxrpc_sock *rx,
+				    struct rxrpc_call *call,
+				    long *timeo)
+{
+	DECLARE_WAITQUEUE(myself, current);
+	int ret;
+
+	_enter(",{%d},%ld",
+	       CIRC_SPACE(call->acks_head, call->acks_tail, call->acks_winsz),
+	       *timeo);
+
+	add_wait_queue(&call->tx_waitq, &myself);
+
+	for (;;) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		ret = 0;
+		if (CIRC_SPACE(call->acks_head, call->acks_tail,
+			       call->acks_winsz) > 0)
+			break;
+		if (signal_pending(current)) {
+			ret = sock_intr_errno(*timeo);
+			break;
+		}
+
+		release_sock(&rx->sk);
+		*timeo = schedule_timeout(*timeo);
+		lock_sock(&rx->sk);
+	}
+
+	remove_wait_queue(&call->tx_waitq, &myself);
+	set_current_state(TASK_RUNNING);
+	_leave(" = %d", ret);
+	return ret;
+}
+
+/*
+ * attempt to schedule an instant Tx resend
+ */
+static inline void rxrpc_instant_resend(struct rxrpc_call *call)
+{
+	read_lock_bh(&call->state_lock);
+	if (try_to_del_timer_sync(&call->resend_timer) >= 0) {
+		clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
+		if (call->state < RXRPC_CALL_COMPLETE &&
+		    !test_and_set_bit(RXRPC_CALL_RESEND_TIMER, &call->events))
+			schedule_work(&call->processor);
+	}
+	read_unlock_bh(&call->state_lock);
+}
+
+/*
+ * queue a packet for transmission, set the resend timer and attempt
+ * to send the packet immediately
+ */
+static void rxrpc_queue_packet(struct rxrpc_call *call, struct sk_buff *skb,
+			       bool last)
+{
+	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+	int ret;
+
+	_net("queue skb %p [%d]", skb, call->acks_head);
+
+	ASSERT(call->acks_window != NULL);
+	call->acks_window[call->acks_head] = (unsigned long) skb;
+	smp_wmb();
+	call->acks_head = (call->acks_head + 1) & (call->acks_winsz - 1);
+
+	if (last || call->state == RXRPC_CALL_SERVER_ACK_REQUEST) {
+		_debug("________awaiting reply/ACK__________");
+		write_lock_bh(&call->state_lock);
+		switch (call->state) {
+		case RXRPC_CALL_CLIENT_SEND_REQUEST:
+			call->state = RXRPC_CALL_CLIENT_AWAIT_REPLY;
+			break;
+		case RXRPC_CALL_SERVER_ACK_REQUEST:
+			call->state = RXRPC_CALL_SERVER_SEND_REPLY;
+			if (!last)
+				break;
+		case RXRPC_CALL_SERVER_SEND_REPLY:
+			call->state = RXRPC_CALL_SERVER_AWAIT_ACK;
+			break;
+		default:
+			break;
+		}
+		write_unlock_bh(&call->state_lock);
+	}
+
+	_proto("Tx DATA %%%u { #%u }",
+	       ntohl(sp->hdr.serial), ntohl(sp->hdr.seq));
+
+	sp->need_resend = 0;
+	sp->resend_at = jiffies + rxrpc_resend_timeout * HZ;
+	if (!test_and_set_bit(RXRPC_CALL_RUN_RTIMER, &call->flags)) {
+		_debug("run timer");
+		call->resend_timer.expires = sp->resend_at;
+		add_timer(&call->resend_timer);
+	}
+
+	/* attempt to cancel the rx-ACK timer, deferring reply transmission if
+	 * we're ACK'ing the request phase of an incoming call */
+	ret = -EAGAIN;
+	if (try_to_del_timer_sync(&call->ack_timer) >= 0) {
+		/* the packet may be freed by rxrpc_process_call() before this
+		 * returns */
+		ret = rxrpc_send_packet(call->conn->trans, skb);
+		_net("sent skb %p", skb);
+	} else {
+		_debug("failed to delete ACK timer");
+	}
+
+	if (ret < 0) {
+		_debug("need instant resend %d", ret);
+		sp->need_resend = 1;
+		rxrpc_instant_resend(call);
+	}
+
+	_leave("");
+}
+
+/*
+ * send data through a socket
+ * - must be called in process context
+ * - caller holds the socket locked
+ */
+static int rxrpc_send_data(struct kiocb *iocb,
+			   struct rxrpc_sock *rx,
+			   struct rxrpc_call *call,
+			   struct msghdr *msg, size_t len)
+{
+	struct rxrpc_skb_priv *sp;
+	unsigned char __user *from;
+	struct sk_buff *skb;
+	struct iovec *iov;
+	struct sock *sk = &rx->sk;
+	long timeo;
+	bool more;
+	int ret, ioc, segment, copied;
+
+	_enter(",,,{%zu},%zu", msg->msg_iovlen, len);
+
+	timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
+
+	/* this should be in poll */
+	clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
+
+	if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
+		return -EPIPE;
+
+	iov = msg->msg_iov;
+	ioc = msg->msg_iovlen - 1;
+	from = iov->iov_base;
+	segment = iov->iov_len;
+	iov++;
+	more = msg->msg_flags & MSG_MORE;
+
+	skb = call->tx_pending;
+	call->tx_pending = NULL;
+
+	copied = 0;
+	do {
+		int copy;
+
+		if (segment > len)
+			segment = len;
+
+		_debug("SEGMENT %d @%p", segment, from);
+
+		if (!skb) {
+			size_t size, chunk, max, space;
+
+			_debug("alloc");
+
+			if (CIRC_SPACE(call->acks_head, call->acks_tail,
+				       call->acks_winsz) <= 0) {
+				ret = -EAGAIN;
+				if (msg->msg_flags & MSG_DONTWAIT)
+					goto maybe_error;
+				ret = rxrpc_wait_for_tx_window(rx, call,
+							       &timeo);
+				if (ret < 0)
+					goto maybe_error;
+			}
+
+			max = call->conn->trans->peer->maxdata;
+			max -= call->conn->security_size;
+			max &= ~(call->conn->size_align - 1UL);
+
+			chunk = max;
+			if (chunk > len)
+				chunk = len;
+
+			space = chunk + call->conn->size_align;
+			space &= ~(call->conn->size_align - 1UL);
+
+			size = space + call->conn->header_size;
+
+			_debug("SIZE: %zu/%zu/%zu", chunk, space, size);
+
+			/* create a buffer that we can retain until it's ACK'd */
+			skb = sock_alloc_send_skb(
+				sk, size, msg->msg_flags & MSG_DONTWAIT, &ret);
+			if (!skb)
+				goto maybe_error;
+
+			rxrpc_new_skb(skb);
+
+			_debug("ALLOC SEND %p", skb);
+
+			ASSERTCMP(skb->mark, ==, 0);
+
+			_debug("HS: %u", call->conn->header_size);
+			skb_reserve(skb, call->conn->header_size);
+			skb->len += call->conn->header_size;
+
+			sp = rxrpc_skb(skb);
+			sp->remain = chunk;
+			if (sp->remain > skb_tailroom(skb))
+				sp->remain = skb_tailroom(skb);
+
+			_net("skb: hr %d, tr %d, hl %d, rm %d",
+			       skb_headroom(skb),
+			       skb_tailroom(skb),
+			       skb_headlen(skb),
+			       sp->remain);
+
+			skb->ip_summed = CHECKSUM_UNNECESSARY;
+		}
+
+		_debug("append");
+		sp = rxrpc_skb(skb);
+
+		/* append next segment of data to the current buffer */
+		copy = skb_tailroom(skb);
+		ASSERTCMP(copy, >, 0);
+		if (copy > segment)
+			copy = segment;
+		if (copy > sp->remain)
+			copy = sp->remain;
+
+		_debug("add");
+		ret = skb_add_data(skb, from, copy);
+		_debug("added");
+		if (ret < 0)
+			goto efault;
+		sp->remain -= copy;
+		skb->mark += copy;
+
+		len -= copy;
+		segment -= copy;
+		from += copy;
+		while (segment == 0 && ioc > 0) {
+			from = iov->iov_base;
+			segment = iov->iov_len;
+			iov++;
+			ioc--;
+		}
+		if (len == 0) {
+			segment = 0;
+			ioc = 0;
+		}
+
+		/* check for the far side aborting the call or a network error
+		 * occurring */
+		if (call->state > RXRPC_CALL_COMPLETE)
+			goto call_aborted;
+
+		/* add the packet to the send queue if it's now full */
+		if (sp->remain <= 0 || (segment == 0 && !more)) {
+			struct rxrpc_connection *conn = call->conn;
+			size_t pad;
+
+			/* pad out if we're using security */
+			if (conn->security) {
+				pad = conn->security_size + skb->mark;
+				pad = conn->size_align - pad;
+				pad &= conn->size_align - 1;
+				_debug("pad %zu", pad);
+				if (pad)
+					memset(skb_put(skb, pad), 0, pad);
+			}
+
+			sp->hdr.epoch = conn->epoch;
+			sp->hdr.cid = call->cid;
+			sp->hdr.callNumber = call->call_id;
+			sp->hdr.seq =
+				htonl(atomic_inc_return(&call->sequence));
+			sp->hdr.serial =
+				htonl(atomic_inc_return(&conn->serial));
+			sp->hdr.type = RXRPC_PACKET_TYPE_DATA;
+			sp->hdr.userStatus = 0;
+			sp->hdr.securityIndex = conn->security_ix;
+			sp->hdr._rsvd = 0;
+			sp->hdr.serviceId = conn->service_id;
+
+			sp->hdr.flags = conn->out_clientflag;
+			if (len == 0 && !more)
+				sp->hdr.flags |= RXRPC_LAST_PACKET;
+			else if (CIRC_SPACE(call->acks_head, call->acks_tail,
+					    call->acks_winsz) > 1)
+				sp->hdr.flags |= RXRPC_MORE_PACKETS;
+
+			ret = rxrpc_secure_packet(
+				call, skb, skb->mark,
+				skb->head + sizeof(struct rxrpc_header));
+			if (ret < 0)
+				goto out;
+
+			memcpy(skb->head, &sp->hdr,
+			       sizeof(struct rxrpc_header));
+			rxrpc_queue_packet(call, skb, segment == 0 && !more);
+			skb = NULL;
+		}
+
+	} while (segment > 0);
+
+out:
+	call->tx_pending = skb;
+	_leave(" = %d", ret);
+	return ret;
+
+call_aborted:
+	rxrpc_free_skb(skb);
+	if (call->state == RXRPC_CALL_NETWORK_ERROR)
+		ret = call->conn->trans->peer->net_error;
+	else
+		ret = -ECONNABORTED;
+	_leave(" = %d", ret);
+	return ret;
+
+maybe_error:
+	if (copied)
+		ret = copied;
+	goto out;
+
+efault:
+	ret = -EFAULT;
+	goto out;
+}