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tun: fix tun_chr_aio_write so that aio works

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aio_write gets const struct iovec * but tun_chr_aio_write casts this to struct
iovec * and modifies the iovec. As a result, attempts to use io_submit
to send packets to a tun device fail with weird errors such as EINVAL.

Since tun is the only user of skb_copy_datagram_from_iovec, we can
fix this simply by changing the later so that it does not
touch the iovec passed to it.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Michael S. Tsirkin 2009-04-20 01:26:11 +00:00 committed by David S. Miller
parent 43b39dcdbd
commit 6f26c9a755
5 changed files with 30 additions and 17 deletions
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13
drivers/net/tun.c
View File

@ -540,31 +540,34 @@ static inline struct sk_buff *tun_alloc_skb(struct tun_struct *tun,
/* Get packet from user space buffer */
static __inline__ ssize_t tun_get_user(struct tun_struct *tun,
struct iovec *iv, size_t count,
const struct iovec *iv, size_t count,
int noblock)
{
struct tun_pi pi = { 0, cpu_to_be16(ETH_P_IP) };
struct sk_buff *skb;
size_t len = count, align = 0;
struct virtio_net_hdr gso = { 0 };
int offset = 0;
if (!(tun->flags & TUN_NO_PI)) {
if ((len -= sizeof(pi)) > count)
return -EINVAL;
if(memcpy_fromiovec((void *)&pi, iv, sizeof(pi)))
if (memcpy_fromiovecend((void *)&pi, iv, 0, sizeof(pi)))
return -EFAULT;
offset += sizeof(pi);
}
if (tun->flags & TUN_VNET_HDR) {
if ((len -= sizeof(gso)) > count)
return -EINVAL;
if (memcpy_fromiovec((void *)&gso, iv, sizeof(gso)))
if (memcpy_fromiovecend((void *)&gso, iv, offset, sizeof(gso)))
return -EFAULT;
if (gso.hdr_len > len)
return -EINVAL;
offset += sizeof(pi);
}
if ((tun->flags & TUN_TYPE_MASK) == TUN_TAP_DEV) {
@ -581,7 +584,7 @@ static __inline__ ssize_t tun_get_user(struct tun_struct *tun,
return PTR_ERR(skb);
}
if (skb_copy_datagram_from_iovec(skb, 0, iv, len)) {
if (skb_copy_datagram_from_iovec(skb, 0, iv, offset, len)) {
tun->dev->stats.rx_dropped++;
kfree_skb(skb);
return -EFAULT;
@ -673,7 +676,7 @@ static ssize_t tun_chr_aio_write(struct kiocb *iocb, const struct iovec *iv,
DBG(KERN_INFO "%s: tun_chr_write %ld\n", tun->dev->name, count);
result = tun_get_user(tun, (struct iovec *)iv, iov_length(iv, count),
result = tun_get_user(tun, iv, iov_length(iv, count),
file->f_flags & O_NONBLOCK);
tun_put(tun);

3
include/linux/skbuff.h
View File

@ -1715,7 +1715,8 @@ extern int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,
struct iovec *iov);
extern int skb_copy_datagram_from_iovec(struct sk_buff *skb,
int offset,
struct iovec *from,
const struct iovec *from,
int from_offset,
int len);
extern int skb_copy_datagram_const_iovec(const struct sk_buff *from,
int offset,

2
include/linux/socket.h
View File

@ -309,7 +309,7 @@ struct ucred {
#ifdef __KERNEL__
extern int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len);
extern int memcpy_fromiovecend(unsigned char *kdata, struct iovec *iov,
extern int memcpy_fromiovecend(unsigned char *kdata, const struct iovec *iov,
int offset, int len);
extern int csum_partial_copy_fromiovecend(unsigned char *kdata,
struct iovec *iov,

20
net/core/datagram.c
View File

@ -435,13 +435,15 @@ EXPORT_SYMBOL(skb_copy_datagram_const_iovec);
* @skb: buffer to copy
* @offset: offset in the buffer to start copying to
* @from: io vector to copy to
* @from_offset: offset in the io vector to start copying from
* @len: amount of data to copy to buffer from iovec
*
* Returns 0 or -EFAULT.
* Note: the iovec is modified during the copy.
* Note: the iovec is not modified during the copy.
*/
int skb_copy_datagram_from_iovec(struct sk_buff *skb, int offset,
struct iovec *from, int len)
const struct iovec *from, int from_offset,
int len)
{
int start = skb_headlen(skb);
int i, copy = start - offset;
@ -450,11 +452,12 @@ int skb_copy_datagram_from_iovec(struct sk_buff *skb, int offset,
if (copy > 0) {
if (copy > len)
copy = len;
if (memcpy_fromiovec(skb->data + offset, from, copy))
if (memcpy_fromiovecend(skb->data + offset, from, 0, copy))
goto fault;
if ((len -= copy) == 0)
return 0;
offset += copy;
from_offset += copy;
}
/* Copy paged appendix. Hmm... why does this look so complicated? */
@ -473,8 +476,9 @@ int skb_copy_datagram_from_iovec(struct sk_buff *skb, int offset,
if (copy > len)
copy = len;
vaddr = kmap(page);
err = memcpy_fromiovec(vaddr + frag->page_offset +
offset - start, from, copy);
err = memcpy_fromiovecend(vaddr + frag->page_offset +
offset - start,
from, from_offset, copy);
kunmap(page);
if (err)
goto fault;
@ -482,6 +486,7 @@ int skb_copy_datagram_from_iovec(struct sk_buff *skb, int offset,
if (!(len -= copy))
return 0;
offset += copy;
from_offset += copy;
}
start = end;
}
@ -500,11 +505,14 @@ int skb_copy_datagram_from_iovec(struct sk_buff *skb, int offset,
copy = len;
if (skb_copy_datagram_from_iovec(list,
offset - start,
from, copy))
from,
from_offset,
copy))
goto fault;
if ((len -= copy) == 0)
return 0;
offset += copy;
from_offset += copy;
}
start = end;
}

7
net/core/iovec.c
View File

@ -147,10 +147,11 @@ int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len)
}
/*
* For use with ip_build_xmit
* Copy iovec from kernel. Returns -EFAULT on error.
*/
int memcpy_fromiovecend(unsigned char *kdata, struct iovec *iov, int offset,
int len)
int memcpy_fromiovecend(unsigned char *kdata, const struct iovec *iov,
int offset, int len)
{
/* Skip over the finished iovecs */
while (offset >= iov->iov_len) {