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linux/net/phonet/pep-gprs.c
David S. Miller 676d23690f net: Fix use after free by removing length arg from sk_data_ready callbacks. 
Several spots in the kernel perform a sequence like:

	skb_queue_tail(&sk->s_receive_queue, skb);
	sk->sk_data_ready(sk, skb->len);

But at the moment we place the SKB onto the socket receive queue it
can be consumed and freed up.  So this skb->len access is potentially
to freed up memory.

Furthermore, the skb->len can be modified by the consumer so it is
possible that the value isn't accurate.

And finally, no actual implementation of this callback actually uses
the length argument.  And since nobody actually cared about it's
value, lots of call sites pass arbitrary values in such as '0' and
even '1'.

So just remove the length argument from the callback, that way there
is no confusion whatsoever and all of these use-after-free cases get
fixed as a side effect.

Based upon a patch by Eric Dumazet and his suggestion to audit this
issue tree-wide.

Signed-off-by: David S. Miller <davem@davemloft.net>
2014-04-11 16:15:36 -04:00

329 lines
6.8 KiB
C
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/*
* File: pep-gprs.c
*
* GPRS over Phonet pipe end point socket
*
* Copyright (C) 2008 Nokia Corporation.
*
* Author: Rémi Denis-Courmont
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*/
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/if_ether.h>
#include <linux/if_arp.h>
#include <net/sock.h>
#include <linux/if_phonet.h>
#include <net/tcp_states.h>
#include <net/phonet/gprs.h>
#define GPRS_DEFAULT_MTU 1400
struct gprs_dev {
struct sock *sk;
void (*old_state_change)(struct sock *);
void (*old_data_ready)(struct sock *);
void (*old_write_space)(struct sock *);
struct net_device *dev;
};
static __be16 gprs_type_trans(struct sk_buff *skb)
{
const u8 *pvfc;
u8 buf;
pvfc = skb_header_pointer(skb, 0, 1, &buf);
if (!pvfc)
return htons(0);
/* Look at IP version field */
switch (*pvfc >> 4) {
case 4:
return htons(ETH_P_IP);
case 6:
return htons(ETH_P_IPV6);
}
return htons(0);
}
static void gprs_writeable(struct gprs_dev *gp)
{
struct net_device *dev = gp->dev;
if (pep_writeable(gp->sk))
netif_wake_queue(dev);
}
/*
* Socket callbacks
*/
static void gprs_state_change(struct sock *sk)
{
struct gprs_dev *gp = sk->sk_user_data;
if (sk->sk_state == TCP_CLOSE_WAIT) {
struct net_device *dev = gp->dev;
netif_stop_queue(dev);
netif_carrier_off(dev);
}
}
static int gprs_recv(struct gprs_dev *gp, struct sk_buff *skb)
{
struct net_device *dev = gp->dev;
int err = 0;
__be16 protocol = gprs_type_trans(skb);
if (!protocol) {
err = -EINVAL;
goto drop;
}
if (skb_headroom(skb) & 3) {
struct sk_buff *rskb, *fs;
int flen = 0;
/* Phonet Pipe data header may be misaligned (3 bytes),
* so wrap the IP packet as a single fragment of an head-less
* socket buffer. The network stack will pull what it needs,
* but at least, the whole IP payload is not memcpy'd. */
rskb = netdev_alloc_skb(dev, 0);
if (!rskb) {
err = -ENOBUFS;
goto drop;
}
skb_shinfo(rskb)->frag_list = skb;
rskb->len += skb->len;
rskb->data_len += rskb->len;
rskb->truesize += rskb->len;
/* Avoid nested fragments */
skb_walk_frags(skb, fs)
flen += fs->len;
skb->next = skb_shinfo(skb)->frag_list;
skb_frag_list_init(skb);
skb->len -= flen;
skb->data_len -= flen;
skb->truesize -= flen;
skb = rskb;
}
skb->protocol = protocol;
skb_reset_mac_header(skb);
skb->dev = dev;
if (likely(dev->flags & IFF_UP)) {
dev->stats.rx_packets++;
dev->stats.rx_bytes += skb->len;
netif_rx(skb);
skb = NULL;
} else
err = -ENODEV;
drop:
if (skb) {
dev_kfree_skb(skb);
dev->stats.rx_dropped++;
}
return err;
}
static void gprs_data_ready(struct sock *sk)
{
struct gprs_dev *gp = sk->sk_user_data;
struct sk_buff *skb;
while ((skb = pep_read(sk)) != NULL) {
skb_orphan(skb);
gprs_recv(gp, skb);
}
}
static void gprs_write_space(struct sock *sk)
{
struct gprs_dev *gp = sk->sk_user_data;
if (netif_running(gp->dev))
gprs_writeable(gp);
}
/*
* Network device callbacks
*/
static int gprs_open(struct net_device *dev)
{
struct gprs_dev *gp = netdev_priv(dev);
gprs_writeable(gp);
return 0;
}
static int gprs_close(struct net_device *dev)
{
netif_stop_queue(dev);
return 0;
}
static netdev_tx_t gprs_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct gprs_dev *gp = netdev_priv(dev);
struct sock *sk = gp->sk;
int len, err;
switch (skb->protocol) {
case htons(ETH_P_IP):
case htons(ETH_P_IPV6):
break;
default:
dev_kfree_skb(skb);
return NETDEV_TX_OK;
}
skb_orphan(skb);
skb_set_owner_w(skb, sk);
len = skb->len;
err = pep_write(sk, skb);
if (err) {
LIMIT_NETDEBUG(KERN_WARNING"%s: TX error (%d)\n",
dev->name, err);
dev->stats.tx_aborted_errors++;
dev->stats.tx_errors++;
} else {
dev->stats.tx_packets++;
dev->stats.tx_bytes += len;
}
netif_stop_queue(dev);
if (pep_writeable(sk))
netif_wake_queue(dev);
return NETDEV_TX_OK;
}
static int gprs_set_mtu(struct net_device *dev, int new_mtu)
{
if ((new_mtu < 576) || (new_mtu > (PHONET_MAX_MTU - 11)))
return -EINVAL;
dev->mtu = new_mtu;
return 0;
}
static const struct net_device_ops gprs_netdev_ops = {
.ndo_open = gprs_open,
.ndo_stop = gprs_close,
.ndo_start_xmit = gprs_xmit,
.ndo_change_mtu = gprs_set_mtu,
};
static void gprs_setup(struct net_device *dev)
{
dev->features = NETIF_F_FRAGLIST;
dev->type = ARPHRD_PHONET_PIPE;
dev->flags = IFF_POINTOPOINT | IFF_NOARP;
dev->mtu = GPRS_DEFAULT_MTU;
dev->hard_header_len = 0;
dev->addr_len = 0;
dev->tx_queue_len = 10;
dev->netdev_ops = &gprs_netdev_ops;
dev->destructor = free_netdev;
}
/*
* External interface
*/
/*
* Attach a GPRS interface to a datagram socket.
* Returns the interface index on success, negative error code on error.
*/
int gprs_attach(struct sock *sk)
{
static const char ifname[] = "gprs%d";
struct gprs_dev *gp;
struct net_device *dev;
int err;
if (unlikely(sk->sk_type == SOCK_STREAM))
return -EINVAL; /* need packet boundaries */
/* Create net device */
dev = alloc_netdev(sizeof(*gp), ifname, gprs_setup);
if (!dev)
return -ENOMEM;
gp = netdev_priv(dev);
gp->sk = sk;
gp->dev = dev;
netif_stop_queue(dev);
err = register_netdev(dev);
if (err) {
free_netdev(dev);
return err;
}
lock_sock(sk);
if (unlikely(sk->sk_user_data)) {
err = -EBUSY;
goto out_rel;
}
if (unlikely((1 << sk->sk_state & (TCPF_CLOSE|TCPF_LISTEN)) ||
sock_flag(sk, SOCK_DEAD))) {
err = -EINVAL;
goto out_rel;
}
sk->sk_user_data = gp;
gp->old_state_change = sk->sk_state_change;
gp->old_data_ready = sk->sk_data_ready;
gp->old_write_space = sk->sk_write_space;
sk->sk_state_change = gprs_state_change;
sk->sk_data_ready = gprs_data_ready;
sk->sk_write_space = gprs_write_space;
release_sock(sk);
sock_hold(sk);
printk(KERN_DEBUG"%s: attached\n", dev->name);
return dev->ifindex;
out_rel:
release_sock(sk);
unregister_netdev(dev);
return err;
}
void gprs_detach(struct sock *sk)
{
struct gprs_dev *gp = sk->sk_user_data;
struct net_device *dev = gp->dev;
lock_sock(sk);
sk->sk_user_data = NULL;
sk->sk_state_change = gp->old_state_change;
sk->sk_data_ready = gp->old_data_ready;
sk->sk_write_space = gp->old_write_space;
release_sock(sk);
printk(KERN_DEBUG"%s: detached\n", dev->name);
unregister_netdev(dev);
sock_put(sk);
}
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