net/tipc/msg.c

/*
 * net/tipc/msg.c: TIPC message header routines
 *
 * Copyright (c) 2000-2006, 2014, Ericsson AB
 * Copyright (c) 2005, 2010-2011, Wind River Systems
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the names of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "core.h"
#include "msg.h"

#define MAX_FORWARD_SIZE 1024

static unsigned int align(unsigned int i)
{
	return (i + 3) & ~3u;
}

void tipc_msg_init(struct tipc_msg *m, u32 user, u32 type, u32 hsize,
		   u32 destnode)
{
	memset(m, 0, hsize);
	msg_set_version(m);
	msg_set_user(m, user);
	msg_set_hdr_sz(m, hsize);
	msg_set_size(m, hsize);
	msg_set_prevnode(m, tipc_own_addr);
	msg_set_type(m, type);
	msg_set_orignode(m, tipc_own_addr);
	msg_set_destnode(m, destnode);
}

/**
 * tipc_msg_build - create message using specified header and data
 *
 * Note: Caller must not hold any locks in case copy_from_user() is interrupted!
 *
 * Returns message data size or errno
 */
int tipc_msg_build(struct tipc_msg *hdr, struct iovec const *msg_sect,
		   unsigned int len, int max_size, struct sk_buff **buf)
{
	int dsz, sz, hsz;
	unsigned char *to;

	dsz = len;
	hsz = msg_hdr_sz(hdr);
	sz = hsz + dsz;
	msg_set_size(hdr, sz);
	if (unlikely(sz > max_size)) {
		*buf = NULL;
		return dsz;
	}

	*buf = tipc_buf_acquire(sz);
	if (!(*buf))
		return -ENOMEM;
	skb_copy_to_linear_data(*buf, hdr, hsz);
	to = (*buf)->data + hsz;
	if (len && memcpy_fromiovecend(to, msg_sect, 0, dsz)) {
		kfree_skb(*buf);
		*buf = NULL;
		return -EFAULT;
	}
	return dsz;
}

/* tipc_buf_append(): Append a buffer to the fragment list of another buffer
 * Let first buffer become head buffer
 * Returns 1 and sets *buf to headbuf if chain is complete, otherwise 0
 * Leaves headbuf pointer at NULL if failure
 */
int tipc_buf_append(struct sk_buff **headbuf, struct sk_buff **buf)
{
	struct sk_buff *head = *headbuf;
	struct sk_buff *frag = *buf;
	struct sk_buff *tail;
	struct tipc_msg *msg = buf_msg(frag);
	u32 fragid = msg_type(msg);
	bool headstolen;
	int delta;

	skb_pull(frag, msg_hdr_sz(msg));

	if (fragid == FIRST_FRAGMENT) {
		if (head || skb_unclone(frag, GFP_ATOMIC))
			goto out_free;
		head = *headbuf = frag;
		skb_frag_list_init(head);
		return 0;
	}
	if (!head)
		goto out_free;
	tail = TIPC_SKB_CB(head)->tail;
	if (skb_try_coalesce(head, frag, &headstolen, &delta)) {
		kfree_skb_partial(frag, headstolen);
	} else {
		if (!skb_has_frag_list(head))
			skb_shinfo(head)->frag_list = frag;
		else
			tail->next = frag;
		head->truesize += frag->truesize;
		head->data_len += frag->len;
		head->len += frag->len;
		TIPC_SKB_CB(head)->tail = frag;
	}
	if (fragid == LAST_FRAGMENT) {
		*buf = head;
		TIPC_SKB_CB(head)->tail = NULL;
		*headbuf = NULL;
		return 1;
	}
	*buf = NULL;
	return 0;
out_free:
	pr_warn_ratelimited("Unable to build fragment list\n");
	kfree_skb(*buf);
	return 0;
}


/**
 * tipc_msg_build2 - create buffer chain containing specified header and data
 * @mhdr: Message header, to be prepended to data
 * @iov: User data
 * @offset: Posision in iov to start copying from
 * @dsz: Total length of user data
 * @pktmax: Max packet size that can be used
 * @chain: Buffer or chain of buffers to be returned to caller
 * Returns message data size or errno: -ENOMEM, -EFAULT
 */
int tipc_msg_build2(struct tipc_msg *mhdr, struct iovec const *iov,
		    int offset, int dsz, int pktmax , struct sk_buff **chain)
{
	int mhsz = msg_hdr_sz(mhdr);
	int msz = mhsz + dsz;
	int pktno = 1;
	int pktsz;
	int pktrem = pktmax;
	int drem = dsz;
	struct tipc_msg pkthdr;
	struct sk_buff *buf, *prev;
	char *pktpos;
	int rc;

	msg_set_size(mhdr, msz);

	/* No fragmentation needed? */
	if (likely(msz <= pktmax)) {
		buf = tipc_buf_acquire(msz);
		*chain = buf;
		if (unlikely(!buf))
			return -ENOMEM;
		skb_copy_to_linear_data(buf, mhdr, mhsz);
		pktpos = buf->data + mhsz;
		if (!dsz || !memcpy_fromiovecend(pktpos, iov, offset, dsz))
			return dsz;
		rc = -EFAULT;
		goto error;
	}

	/* Prepare reusable fragment header */
	tipc_msg_init(&pkthdr, MSG_FRAGMENTER, FIRST_FRAGMENT,
		      INT_H_SIZE, msg_destnode(mhdr));
	msg_set_size(&pkthdr, pktmax);
	msg_set_fragm_no(&pkthdr, pktno);

	/* Prepare first fragment */
	*chain = buf = tipc_buf_acquire(pktmax);
	if (!buf)
		return -ENOMEM;
	pktpos = buf->data;
	skb_copy_to_linear_data(buf, &pkthdr, INT_H_SIZE);
	pktpos += INT_H_SIZE;
	pktrem -= INT_H_SIZE;
	skb_copy_to_linear_data_offset(buf, INT_H_SIZE, mhdr, mhsz);
	pktpos += mhsz;
	pktrem -= mhsz;

	do {
		if (drem < pktrem)
			pktrem = drem;

		if (memcpy_fromiovecend(pktpos, iov, offset, pktrem)) {
			rc = -EFAULT;
			goto error;
		}
		drem -= pktrem;
		offset += pktrem;

		if (!drem)
			break;

		/* Prepare new fragment: */
		if (drem < (pktmax - INT_H_SIZE))
			pktsz = drem + INT_H_SIZE;
		else
			pktsz = pktmax;
		prev = buf;
		buf = tipc_buf_acquire(pktsz);
		if (!buf) {
			rc = -ENOMEM;
			goto error;
		}
		prev->next = buf;
		msg_set_type(&pkthdr, FRAGMENT);
		msg_set_size(&pkthdr, pktsz);
		msg_set_fragm_no(&pkthdr, ++pktno);
		skb_copy_to_linear_data(buf, &pkthdr, INT_H_SIZE);
		pktpos = buf->data + INT_H_SIZE;
		pktrem = pktsz - INT_H_SIZE;

	} while (1);

	msg_set_type(buf_msg(buf), LAST_FRAGMENT);
	return dsz;
error:
	kfree_skb_list(*chain);
	*chain = NULL;
	return rc;
}

/**
 * tipc_msg_bundle(): Append contents of a buffer to tail of an existing one
 * @bbuf: the existing buffer ("bundle")
 * @buf:  buffer to be appended
 * @mtu:  max allowable size for the bundle buffer
 * Consumes buffer if successful
 * Returns true if bundling could be performed, otherwise false
 */
bool tipc_msg_bundle(struct sk_buff *bbuf, struct sk_buff *buf, u32 mtu)
{
	struct tipc_msg *bmsg = buf_msg(bbuf);
	struct tipc_msg *msg = buf_msg(buf);
	unsigned int bsz = msg_size(bmsg);
	unsigned int msz = msg_size(msg);
	u32 start = align(bsz);
	u32 max = mtu - INT_H_SIZE;
	u32 pad = start - bsz;

	if (likely(msg_user(msg) == MSG_FRAGMENTER))
		return false;
	if (unlikely(msg_user(msg) == CHANGEOVER_PROTOCOL))
		return false;
	if (unlikely(msg_user(msg) == BCAST_PROTOCOL))
		return false;
	if (likely(msg_user(bmsg) != MSG_BUNDLER))
		return false;
	if (likely(msg_type(bmsg) != BUNDLE_OPEN))
		return false;
	if (unlikely(skb_tailroom(bbuf) < (pad + msz)))
		return false;
	if (unlikely(max < (start + msz)))
		return false;

	skb_put(bbuf, pad + msz);
	skb_copy_to_linear_data_offset(bbuf, start, buf->data, msz);
	msg_set_size(bmsg, start + msz);
	msg_set_msgcnt(bmsg, msg_msgcnt(bmsg) + 1);
	bbuf->next = buf->next;
	kfree_skb(buf);
	return true;
}

/**
 * tipc_msg_make_bundle(): Create bundle buf and append message to its tail
 * @buf:  buffer to be appended and replaced
 * @mtu:  max allowable size for the bundle buffer, inclusive header
 * @dnode: destination node for message. (Not always present in header)
 * Replaces buffer if successful
 * Returns true if sucess, otherwise false
 */
bool tipc_msg_make_bundle(struct sk_buff **buf, u32 mtu, u32 dnode)
{
	struct sk_buff *bbuf;
	struct tipc_msg *bmsg;
	struct tipc_msg *msg = buf_msg(*buf);
	u32 msz = msg_size(msg);
	u32 max = mtu - INT_H_SIZE;

	if (msg_user(msg) == MSG_FRAGMENTER)
		return false;
	if (msg_user(msg) == CHANGEOVER_PROTOCOL)
		return false;
	if (msg_user(msg) == BCAST_PROTOCOL)
		return false;
	if (msz > (max / 2))
		return false;

	bbuf = tipc_buf_acquire(max);
	if (!bbuf)
		return false;

	skb_trim(bbuf, INT_H_SIZE);
	bmsg = buf_msg(bbuf);
	tipc_msg_init(bmsg, MSG_BUNDLER, BUNDLE_OPEN, INT_H_SIZE, dnode);
	msg_set_seqno(bmsg, msg_seqno(msg));
	msg_set_ack(bmsg, msg_ack(msg));
	msg_set_bcast_ack(bmsg, msg_bcast_ack(msg));
	bbuf->next = (*buf)->next;
	tipc_msg_bundle(bbuf, *buf, mtu);
	*buf = bbuf;
	return true;
}

/**
 * tipc_msg_reverse(): swap source and destination addresses and add error code
 * @buf:  buffer containing message to be reversed
 * @dnode: return value: node where to send message after reversal
 * @err:  error code to be set in message
 * Consumes buffer if failure
 * Returns true if success, otherwise false
 */
bool tipc_msg_reverse(struct sk_buff *buf, u32 *dnode, int err)
{
	struct tipc_msg *msg = buf_msg(buf);
	uint imp = msg_importance(msg);
	struct tipc_msg ohdr;
	uint rdsz = min_t(uint, msg_data_sz(msg), MAX_FORWARD_SIZE);

	if (skb_linearize(buf) || !msg_isdata(msg))
		goto exit;
	if (msg_dest_droppable(msg) || msg_errcode(msg))
		goto exit;

	memcpy(&ohdr, msg, msg_hdr_sz(msg));
	msg_set_importance(msg, min_t(uint, ++imp, TIPC_CRITICAL_IMPORTANCE));
	msg_set_errcode(msg, err);
	msg_set_origport(msg, msg_destport(&ohdr));
	msg_set_destport(msg, msg_origport(&ohdr));
	msg_set_prevnode(msg, tipc_own_addr);
	if (!msg_short(msg)) {
		msg_set_orignode(msg, msg_destnode(&ohdr));
		msg_set_destnode(msg, msg_orignode(&ohdr));
	}
	msg_set_size(msg, msg_hdr_sz(msg) + rdsz);
	skb_trim(buf, msg_size(msg));
	skb_orphan(buf);
	*dnode = msg_orignode(&ohdr);
	return true;
exit:
	kfree_skb(buf);
	return false;
}