linux/net/tipc/msg.c
Jon Paul Maloy c637c10355 tipc: resolve race problem at unicast message reception
TIPC handles message cardinality and sequencing at the link layer,
before passing messages upwards to the destination sockets. During the
upcall from link to socket no locks are held. It is therefore possible,
and we see it happen occasionally, that messages arriving in different
threads and delivered in sequence still bypass each other before they
reach the destination socket. This must not happen, since it violates
the sequentiality guarantee.

We solve this by adding a new input buffer queue to the link structure.
Arriving messages are added safely to the tail of that queue by the
link, while the head of the queue is consumed, also safely, by the
receiving socket. Sequentiality is secured per socket by only allowing
buffers to be dequeued inside the socket lock. Since there may be multiple
simultaneous readers of the queue, we use a 'filter' parameter to reduce
the risk that they peek the same buffer from the queue, hence also
reducing the risk of contention on the receiving socket locks.

This solves the sequentiality problem, and seems to cause no measurable
performance degradation.

A nice side effect of this change is that lock handling in the functions
tipc_rcv() and tipc_bcast_rcv() now becomes uniform, something that
will enable future simplifications of those functions.

Reviewed-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-05 16:00:02 -08:00

521 lines
14 KiB
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 <net/sock.h>
#include "core.h"
#include "msg.h"
#include "addr.h"
#include "name_table.h"
#define MAX_FORWARD_SIZE 1024
static unsigned int align(unsigned int i)
{
return (i + 3) & ~3u;
}
/**
* tipc_buf_acquire - creates a TIPC message buffer
* @size: message size (including TIPC header)
*
* Returns a new buffer with data pointers set to the specified size.
*
* NOTE: Headroom is reserved to allow prepending of a data link header.
* There may also be unrequested tailroom present at the buffer's end.
*/
struct sk_buff *tipc_buf_acquire(u32 size)
{
struct sk_buff *skb;
unsigned int buf_size = (BUF_HEADROOM + size + 3) & ~3u;
skb = alloc_skb_fclone(buf_size, GFP_ATOMIC);
if (skb) {
skb_reserve(skb, BUF_HEADROOM);
skb_put(skb, size);
skb->next = NULL;
}
return skb;
}
void tipc_msg_init(u32 own_node, struct tipc_msg *m, u32 user, u32 type,
u32 hsize, u32 dnode)
{
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, own_node);
msg_set_type(m, type);
if (hsize > SHORT_H_SIZE) {
msg_set_orignode(m, own_node);
msg_set_destnode(m, dnode);
}
}
struct sk_buff *tipc_msg_create(uint user, uint type,
uint hdr_sz, uint data_sz, u32 dnode,
u32 onode, u32 dport, u32 oport, int errcode)
{
struct tipc_msg *msg;
struct sk_buff *buf;
buf = tipc_buf_acquire(hdr_sz + data_sz);
if (unlikely(!buf))
return NULL;
msg = buf_msg(buf);
tipc_msg_init(onode, msg, user, type, hdr_sz, dnode);
msg_set_size(msg, hdr_sz + data_sz);
msg_set_origport(msg, oport);
msg_set_destport(msg, dport);
msg_set_errcode(msg, errcode);
if (hdr_sz > SHORT_H_SIZE) {
msg_set_orignode(msg, onode);
msg_set_destnode(msg, dnode);
}
return buf;
}
/* tipc_buf_append(): Append a buffer to the fragment list of another buffer
* @*headbuf: in: NULL for first frag, otherwise value returned from prev call
* out: set when successful non-complete reassembly, otherwise NULL
* @*buf: in: the buffer to append. Always defined
* out: head buf after successful complete reassembly, otherwise NULL
* Returns 1 when reassembly complete, otherwise 0
*/
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;
u32 fragid;
int delta;
bool headstolen;
if (!frag)
goto err;
msg = buf_msg(frag);
fragid = msg_type(msg);
frag->next = NULL;
skb_pull(frag, msg_hdr_sz(msg));
if (fragid == FIRST_FRAGMENT) {
if (unlikely(head))
goto err;
if (unlikely(skb_unclone(frag, GFP_ATOMIC)))
goto err;
head = *headbuf = frag;
skb_frag_list_init(head);
TIPC_SKB_CB(head)->tail = NULL;
*buf = NULL;
return 0;
}
if (!head)
goto err;
if (skb_try_coalesce(head, frag, &headstolen, &delta)) {
kfree_skb_partial(frag, headstolen);
} else {
tail = TIPC_SKB_CB(head)->tail;
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;
err:
pr_warn_ratelimited("Unable to build fragment list\n");
kfree_skb(*buf);
kfree_skb(*headbuf);
*buf = *headbuf = NULL;
return 0;
}
/**
* tipc_msg_build - create buffer chain containing specified header and data
* @mhdr: Message header, to be prepended to data
* @m: User message
* @dsz: Total length of user data
* @pktmax: Max packet size that can be used
* @list: Buffer or chain of buffers to be returned to caller
*
* Returns message data size or errno: -ENOMEM, -EFAULT
*/
int tipc_msg_build(struct tipc_msg *mhdr, struct msghdr *m,
int offset, int dsz, int pktmax, struct sk_buff_head *list)
{
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 *skb;
char *pktpos;
int rc;
msg_set_size(mhdr, msz);
/* No fragmentation needed? */
if (likely(msz <= pktmax)) {
skb = tipc_buf_acquire(msz);
if (unlikely(!skb))
return -ENOMEM;
skb_orphan(skb);
__skb_queue_tail(list, skb);
skb_copy_to_linear_data(skb, mhdr, mhsz);
pktpos = skb->data + mhsz;
if (copy_from_iter(pktpos, dsz, &m->msg_iter) == dsz)
return dsz;
rc = -EFAULT;
goto error;
}
/* Prepare reusable fragment header */
tipc_msg_init(msg_prevnode(mhdr), &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 */
skb = tipc_buf_acquire(pktmax);
if (!skb)
return -ENOMEM;
skb_orphan(skb);
__skb_queue_tail(list, skb);
pktpos = skb->data;
skb_copy_to_linear_data(skb, &pkthdr, INT_H_SIZE);
pktpos += INT_H_SIZE;
pktrem -= INT_H_SIZE;
skb_copy_to_linear_data_offset(skb, INT_H_SIZE, mhdr, mhsz);
pktpos += mhsz;
pktrem -= mhsz;
do {
if (drem < pktrem)
pktrem = drem;
if (copy_from_iter(pktpos, pktrem, &m->msg_iter) != pktrem) {
rc = -EFAULT;
goto error;
}
drem -= pktrem;
if (!drem)
break;
/* Prepare new fragment: */
if (drem < (pktmax - INT_H_SIZE))
pktsz = drem + INT_H_SIZE;
else
pktsz = pktmax;
skb = tipc_buf_acquire(pktsz);
if (!skb) {
rc = -ENOMEM;
goto error;
}
skb_orphan(skb);
__skb_queue_tail(list, skb);
msg_set_type(&pkthdr, FRAGMENT);
msg_set_size(&pkthdr, pktsz);
msg_set_fragm_no(&pkthdr, ++pktno);
skb_copy_to_linear_data(skb, &pkthdr, INT_H_SIZE);
pktpos = skb->data + INT_H_SIZE;
pktrem = pktsz - INT_H_SIZE;
} while (1);
msg_set_type(buf_msg(skb), LAST_FRAGMENT);
return dsz;
error:
__skb_queue_purge(list);
__skb_queue_head_init(list);
return rc;
}
/**
* tipc_msg_bundle(): Append contents of a buffer to tail of an existing one
* @list: the buffer chain of the existing buffer ("bundle")
* @skb: 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_head *list, struct sk_buff *skb, u32 mtu)
{
struct sk_buff *bskb = skb_peek_tail(list);
struct tipc_msg *bmsg = buf_msg(bskb);
struct tipc_msg *msg = buf_msg(skb);
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(!TIPC_SKB_CB(bskb)->bundling))
return false;
if (unlikely(skb_tailroom(bskb) < (pad + msz)))
return false;
if (unlikely(max < (start + msz)))
return false;
skb_put(bskb, pad + msz);
skb_copy_to_linear_data_offset(bskb, start, skb->data, msz);
msg_set_size(bmsg, start + msz);
msg_set_msgcnt(bmsg, msg_msgcnt(bmsg) + 1);
kfree_skb(skb);
return true;
}
/**
* tipc_msg_extract(): extract bundled inner packet from buffer
* @skb: linear outer buffer, to be extracted from.
* @iskb: extracted inner buffer, to be returned
* @pos: position of msg to be extracted. Returns with pointer of next msg
* Consumes outer buffer when last packet extracted
* Returns true when when there is an extracted buffer, otherwise false
*/
bool tipc_msg_extract(struct sk_buff *skb, struct sk_buff **iskb, int *pos)
{
struct tipc_msg *msg = buf_msg(skb);
int imsz;
struct tipc_msg *imsg = (struct tipc_msg *)(msg_data(msg) + *pos);
/* Is there space left for shortest possible message? */
if (*pos > (msg_data_sz(msg) - SHORT_H_SIZE))
goto none;
imsz = msg_size(imsg);
/* Is there space left for current message ? */
if ((*pos + imsz) > msg_data_sz(msg))
goto none;
*iskb = tipc_buf_acquire(imsz);
if (!*iskb)
goto none;
skb_copy_to_linear_data(*iskb, imsg, imsz);
*pos += align(imsz);
return true;
none:
kfree_skb(skb);
*iskb = NULL;
return false;
}
/**
* tipc_msg_make_bundle(): Create bundle buf and append message to its tail
* @list: the buffer chain
* @skb: 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 success, otherwise false
*/
bool tipc_msg_make_bundle(struct sk_buff_head *list,
struct sk_buff *skb, u32 mtu, u32 dnode)
{
struct sk_buff *bskb;
struct tipc_msg *bmsg;
struct tipc_msg *msg = buf_msg(skb);
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;
bskb = tipc_buf_acquire(max);
if (!bskb)
return false;
skb_trim(bskb, INT_H_SIZE);
bmsg = buf_msg(bskb);
tipc_msg_init(msg_prevnode(msg), bmsg, MSG_BUNDLER, 0,
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));
TIPC_SKB_CB(bskb)->bundling = true;
__skb_queue_tail(list, bskb);
return tipc_msg_bundle(list, skb, mtu);
}
/**
* 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(u32 own_addr, 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))
goto exit;
if (msg_dest_droppable(msg))
goto exit;
if (msg_errcode(msg))
goto exit;
memcpy(&ohdr, msg, msg_hdr_sz(msg));
imp = min_t(uint, imp + 1, TIPC_CRITICAL_IMPORTANCE);
if (msg_isdata(msg))
msg_set_importance(msg, imp);
msg_set_errcode(msg, err);
msg_set_origport(msg, msg_destport(&ohdr));
msg_set_destport(msg, msg_origport(&ohdr));
msg_set_prevnode(msg, 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);
*dnode = 0;
return false;
}
/**
* tipc_msg_lookup_dest(): try to find new destination for named message
* @skb: the buffer containing the message.
* @dnode: return value: next-hop node, if destination found
* @err: return value: error code to use, if message to be rejected
* Does not consume buffer
* Returns true if a destination is found, false otherwise
*/
bool tipc_msg_lookup_dest(struct net *net, struct sk_buff *skb,
u32 *dnode, int *err)
{
struct tipc_msg *msg = buf_msg(skb);
u32 dport;
if (!msg_isdata(msg))
return false;
if (!msg_named(msg))
return false;
*err = -TIPC_ERR_NO_NAME;
if (skb_linearize(skb))
return false;
if (msg_reroute_cnt(msg) > 0)
return false;
*dnode = addr_domain(net, msg_lookup_scope(msg));
dport = tipc_nametbl_translate(net, msg_nametype(msg),
msg_nameinst(msg), dnode);
if (!dport)
return false;
msg_incr_reroute_cnt(msg);
msg_set_destnode(msg, *dnode);
msg_set_destport(msg, dport);
*err = TIPC_OK;
return true;
}
/* tipc_msg_reassemble() - clone a buffer chain of fragments and
* reassemble the clones into one message
*/
struct sk_buff *tipc_msg_reassemble(struct sk_buff_head *list)
{
struct sk_buff *skb;
struct sk_buff *frag = NULL;
struct sk_buff *head = NULL;
int hdr_sz;
/* Copy header if single buffer */
if (skb_queue_len(list) == 1) {
skb = skb_peek(list);
hdr_sz = skb_headroom(skb) + msg_hdr_sz(buf_msg(skb));
return __pskb_copy(skb, hdr_sz, GFP_ATOMIC);
}
/* Clone all fragments and reassemble */
skb_queue_walk(list, skb) {
frag = skb_clone(skb, GFP_ATOMIC);
if (!frag)
goto error;
frag->next = NULL;
if (tipc_buf_append(&head, &frag))
break;
if (!head)
goto error;
}
return frag;
error:
pr_warn("Failed do clone local mcast rcv buffer\n");
kfree_skb(head);
return NULL;
}