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linux/net/ax25/ax25_in.c
Herbert Xu d55d87fdff net: Move rx skb_orphan call to where needed 
In order to get the tun driver to account packets, we need to be
able to receive packets with destructors set.  To be on the safe
side, I added an skb_orphan call for all protocols by default since
some of them (IP in particular) cannot handle receiving packets
destructors properly.

Now it seems that at least one protocol (CAN) expects to be able
to pass skb->sk through the rx path without getting clobbered.

So this patch attempts to fix this properly by moving the skb_orphan
call to where it's actually needed.  In particular, I've added it
to skb_set_owner_[rw] which is what most users of skb->destructor
call.

This is actually an improvement for tun too since it means that
we only give back the amount charged to the socket when the skb
is passed to another socket that will also be charged accordingly.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Tested-by: Oliver Hartkopp <olver@hartkopp.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2009-06-23 16:36:25 -07:00

456 lines
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/*
* 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.
*
* Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
* Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
* Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
* Copyright (C) Hans-Joachim Hetscher DD8NE (dd8ne@bnv-bamberg.de)
*/
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <net/ax25.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/netfilter.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
/*
* Given a fragment, queue it on the fragment queue and if the fragment
* is complete, send it back to ax25_rx_iframe.
*/
static int ax25_rx_fragment(ax25_cb *ax25, struct sk_buff *skb)
{
struct sk_buff *skbn, *skbo;
if (ax25->fragno != 0) {
if (!(*skb->data & AX25_SEG_FIRST)) {
if ((ax25->fragno - 1) == (*skb->data & AX25_SEG_REM)) {
/* Enqueue fragment */
ax25->fragno = *skb->data & AX25_SEG_REM;
skb_pull(skb, 1); /* skip fragno */
ax25->fraglen += skb->len;
skb_queue_tail(&ax25->frag_queue, skb);
/* Last fragment received ? */
if (ax25->fragno == 0) {
skbn = alloc_skb(AX25_MAX_HEADER_LEN +
ax25->fraglen,
GFP_ATOMIC);
if (!skbn) {
skb_queue_purge(&ax25->frag_queue);
return 1;
}
skb_reserve(skbn, AX25_MAX_HEADER_LEN);
skbn->dev = ax25->ax25_dev->dev;
skb_reset_network_header(skbn);
skb_reset_transport_header(skbn);
/* Copy data from the fragments */
while ((skbo = skb_dequeue(&ax25->frag_queue)) != NULL) {
skb_copy_from_linear_data(skbo,
skb_put(skbn, skbo->len),
skbo->len);
kfree_skb(skbo);
}
ax25->fraglen = 0;
if (ax25_rx_iframe(ax25, skbn) == 0)
kfree_skb(skbn);
}
return 1;
}
}
} else {
/* First fragment received */
if (*skb->data & AX25_SEG_FIRST) {
skb_queue_purge(&ax25->frag_queue);
ax25->fragno = *skb->data & AX25_SEG_REM;
skb_pull(skb, 1); /* skip fragno */
ax25->fraglen = skb->len;
skb_queue_tail(&ax25->frag_queue, skb);
return 1;
}
}
return 0;
}
/*
* This is where all valid I frames are sent to, to be dispatched to
* whichever protocol requires them.
*/
int ax25_rx_iframe(ax25_cb *ax25, struct sk_buff *skb)
{
int (*func)(struct sk_buff *, ax25_cb *);
unsigned char pid;
int queued = 0;
if (skb == NULL) return 0;
ax25_start_idletimer(ax25);
pid = *skb->data;
if (pid == AX25_P_IP) {
/* working around a TCP bug to keep additional listeners
* happy. TCP re-uses the buffer and destroys the original
* content.
*/
struct sk_buff *skbn = skb_copy(skb, GFP_ATOMIC);
if (skbn != NULL) {
kfree_skb(skb);
skb = skbn;
}
skb_pull(skb, 1); /* Remove PID */
skb->mac_header = skb->network_header;
skb_reset_network_header(skb);
skb->dev = ax25->ax25_dev->dev;
skb->pkt_type = PACKET_HOST;
skb->protocol = htons(ETH_P_IP);
netif_rx(skb);
return 1;
}
if (pid == AX25_P_SEGMENT) {
skb_pull(skb, 1); /* Remove PID */
return ax25_rx_fragment(ax25, skb);
}
if ((func = ax25_protocol_function(pid)) != NULL) {
skb_pull(skb, 1); /* Remove PID */
return (*func)(skb, ax25);
}
if (ax25->sk != NULL && ax25->ax25_dev->values[AX25_VALUES_CONMODE] == 2) {
if ((!ax25->pidincl && ax25->sk->sk_protocol == pid) ||
ax25->pidincl) {
if (sock_queue_rcv_skb(ax25->sk, skb) == 0)
queued = 1;
else
ax25->condition |= AX25_COND_OWN_RX_BUSY;
}
}
return queued;
}
/*
* Higher level upcall for a LAPB frame
*/
static int ax25_process_rx_frame(ax25_cb *ax25, struct sk_buff *skb, int type, int dama)
{
int queued = 0;
if (ax25->state == AX25_STATE_0)
return 0;
switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
case AX25_PROTO_STD_SIMPLEX:
case AX25_PROTO_STD_DUPLEX:
queued = ax25_std_frame_in(ax25, skb, type);
break;
#ifdef CONFIG_AX25_DAMA_SLAVE
case AX25_PROTO_DAMA_SLAVE:
if (dama || ax25->ax25_dev->dama.slave)
queued = ax25_ds_frame_in(ax25, skb, type);
else
queued = ax25_std_frame_in(ax25, skb, type);
break;
#endif
}
return queued;
}
static int ax25_rcv(struct sk_buff *skb, struct net_device *dev,
ax25_address *dev_addr, struct packet_type *ptype)
{
ax25_address src, dest, *next_digi = NULL;
int type = 0, mine = 0, dama;
struct sock *make, *sk;
ax25_digi dp, reverse_dp;
ax25_cb *ax25;
ax25_dev *ax25_dev;
/*
* Process the AX.25/LAPB frame.
*/
skb_reset_transport_header(skb);
if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
goto free;
/*
* Parse the address header.
*/
if (ax25_addr_parse(skb->data, skb->len, &src, &dest, &dp, &type, &dama) == NULL)
goto free;
/*
* Ours perhaps ?
*/
if (dp.lastrepeat + 1 < dp.ndigi) /* Not yet digipeated completely */
next_digi = &dp.calls[dp.lastrepeat + 1];
/*
* Pull of the AX.25 headers leaving the CTRL/PID bytes
*/
skb_pull(skb, ax25_addr_size(&dp));
/* For our port addresses ? */
if (ax25cmp(&dest, dev_addr) == 0 && dp.lastrepeat + 1 == dp.ndigi)
mine = 1;
/* Also match on any registered callsign from L3/4 */
if (!mine && ax25_listen_mine(&dest, dev) && dp.lastrepeat + 1 == dp.ndigi)
mine = 1;
/* UI frame - bypass LAPB processing */
if ((*skb->data & ~0x10) == AX25_UI && dp.lastrepeat + 1 == dp.ndigi) {
skb_set_transport_header(skb, 2); /* skip control and pid */
ax25_send_to_raw(&dest, skb, skb->data[1]);
if (!mine && ax25cmp(&dest, (ax25_address *)dev->broadcast) != 0)
goto free;
/* Now we are pointing at the pid byte */
switch (skb->data[1]) {
case AX25_P_IP:
skb_pull(skb,2); /* drop PID/CTRL */
skb_reset_transport_header(skb);
skb_reset_network_header(skb);
skb->dev = dev;
skb->pkt_type = PACKET_HOST;
skb->protocol = htons(ETH_P_IP);
netif_rx(skb);
break;
case AX25_P_ARP:
skb_pull(skb,2);
skb_reset_transport_header(skb);
skb_reset_network_header(skb);
skb->dev = dev;
skb->pkt_type = PACKET_HOST;
skb->protocol = htons(ETH_P_ARP);
netif_rx(skb);
break;
case AX25_P_TEXT:
/* Now find a suitable dgram socket */
sk = ax25_get_socket(&dest, &src, SOCK_DGRAM);
if (sk != NULL) {
bh_lock_sock(sk);
if (atomic_read(&sk->sk_rmem_alloc) >=
sk->sk_rcvbuf) {
kfree_skb(skb);
} else {
/*
* Remove the control and PID.
*/
skb_pull(skb, 2);
if (sock_queue_rcv_skb(sk, skb) != 0)
kfree_skb(skb);
}
bh_unlock_sock(sk);
sock_put(sk);
} else {
kfree_skb(skb);
}
break;
default:
kfree_skb(skb); /* Will scan SOCK_AX25 RAW sockets */
break;
}
return 0;
}
/*
* Is connected mode supported on this device ?
* If not, should we DM the incoming frame (except DMs) or
* silently ignore them. For now we stay quiet.
*/
if (ax25_dev->values[AX25_VALUES_CONMODE] == 0)
goto free;
/* LAPB */
/* AX.25 state 1-4 */
ax25_digi_invert(&dp, &reverse_dp);
if ((ax25 = ax25_find_cb(&dest, &src, &reverse_dp, dev)) != NULL) {
/*
* Process the frame. If it is queued up internally it
* returns one otherwise we free it immediately. This
* routine itself wakes the user context layers so we do
* no further work
*/
if (ax25_process_rx_frame(ax25, skb, type, dama) == 0)
kfree_skb(skb);
ax25_cb_put(ax25);
return 0;
}
/* AX.25 state 0 (disconnected) */
/* a) received not a SABM(E) */
if ((*skb->data & ~AX25_PF) != AX25_SABM &&
(*skb->data & ~AX25_PF) != AX25_SABME) {
/*
* Never reply to a DM. Also ignore any connects for
* addresses that are not our interfaces and not a socket.
*/
if ((*skb->data & ~AX25_PF) != AX25_DM && mine)
ax25_return_dm(dev, &src, &dest, &dp);
goto free;
}
/* b) received SABM(E) */
if (dp.lastrepeat + 1 == dp.ndigi)
sk = ax25_find_listener(&dest, 0, dev, SOCK_SEQPACKET);
else
sk = ax25_find_listener(next_digi, 1, dev, SOCK_SEQPACKET);
if (sk != NULL) {
bh_lock_sock(sk);
if (sk_acceptq_is_full(sk) ||
(make = ax25_make_new(sk, ax25_dev)) == NULL) {
if (mine)
ax25_return_dm(dev, &src, &dest, &dp);
kfree_skb(skb);
bh_unlock_sock(sk);
sock_put(sk);
return 0;
}
ax25 = ax25_sk(make);
skb_set_owner_r(skb, make);
skb_queue_head(&sk->sk_receive_queue, skb);
make->sk_state = TCP_ESTABLISHED;
sk->sk_ack_backlog++;
bh_unlock_sock(sk);
} else {
if (!mine)
goto free;
if ((ax25 = ax25_create_cb()) == NULL) {
ax25_return_dm(dev, &src, &dest, &dp);
goto free;
}
ax25_fillin_cb(ax25, ax25_dev);
}
ax25->source_addr = dest;
ax25->dest_addr = src;
/*
* Sort out any digipeated paths.
*/
if (dp.ndigi && !ax25->digipeat &&
(ax25->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
kfree_skb(skb);
ax25_destroy_socket(ax25);
if (sk)
sock_put(sk);
return 0;
}
if (dp.ndigi == 0) {
kfree(ax25->digipeat);
ax25->digipeat = NULL;
} else {
/* Reverse the source SABM's path */
memcpy(ax25->digipeat, &reverse_dp, sizeof(ax25_digi));
}
if ((*skb->data & ~AX25_PF) == AX25_SABME) {
ax25->modulus = AX25_EMODULUS;
ax25->window = ax25_dev->values[AX25_VALUES_EWINDOW];
} else {
ax25->modulus = AX25_MODULUS;
ax25->window = ax25_dev->values[AX25_VALUES_WINDOW];
}
ax25_send_control(ax25, AX25_UA, AX25_POLLON, AX25_RESPONSE);
#ifdef CONFIG_AX25_DAMA_SLAVE
if (dama && ax25->ax25_dev->values[AX25_VALUES_PROTOCOL] == AX25_PROTO_DAMA_SLAVE)
ax25_dama_on(ax25);
#endif
ax25->state = AX25_STATE_3;
ax25_cb_add(ax25);
ax25_start_heartbeat(ax25);
ax25_start_t3timer(ax25);
ax25_start_idletimer(ax25);
if (sk) {
if (!sock_flag(sk, SOCK_DEAD))
sk->sk_data_ready(sk, skb->len);
sock_put(sk);
} else {
free:
kfree_skb(skb);
}
return 0;
}
/*
* Receive an AX.25 frame via a SLIP interface.
*/
int ax25_kiss_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *ptype, struct net_device *orig_dev)
{
skb_orphan(skb);
if (!net_eq(dev_net(dev), &init_net)) {
kfree_skb(skb);
return 0;
}
if ((*skb->data & 0x0F) != 0) {
kfree_skb(skb); /* Not a KISS data frame */
return 0;
}
skb_pull(skb, AX25_KISS_HEADER_LEN); /* Remove the KISS byte */
return ax25_rcv(skb, dev, (ax25_address *)dev->dev_addr, ptype);
}
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