net: skb_copy_datagram_const_iovec()

PATCH New Michael S. Tsirkin 1 participant 3 messages Apr 20, 2009 1 message not in the archive

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Networking Network drivers Sockets TUN/TAP driver

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A message that is not in the archive (sent off-list or not yet received): [email protected]

Michael S. Tsirkin

author

2009-04-20 11:26 UTC #1 lore raw

PATCH 1/3 net: skb_copy_datagram_const_iovec()

There's an skb_copy_datagram_iovec() to copy out of a paged skb, but it modifies the iovec, and does not support starting at an offset in the destination. We want both in tun.c, so let's add the function.

It's a carbon copy of skb_copy_datagram_iovec() with enough changes to be annoying.

Signed-off-by Michael S. Tsirkin <[email protected]>

---
 include/linux/skbuff.h |    5 +++
 include/linux/socket.h |    2 +
 net/core/datagram.c    |   92 ++++++++++++++++++++++++++++++++++++++++++++++++
 net/core/iovec.c       |   26 +++++++++++++
 4 files changed, 125 insertions(+), 0 deletions(-)

include/linux/skbuff.h +5 -0

index 5fd3891..af2b21b 100644
@@ -1717,6 +1717,11 @@ extern int	       skb_copy_datagram_from_iovec(struct sk_buff *skb,
 						    int offset,
 						    struct iovec *from,
 						    int len);
+extern int	       skb_copy_datagram_const_iovec(const struct sk_buff *from,
+						     int offset,
+						     const struct iovec *to,
+						     int to_offset,
+						     int size);
 extern void	       skb_free_datagram(struct sock *sk, struct sk_buff *skb);
 extern int	       skb_kill_datagram(struct sock *sk, struct sk_buff *skb,
 					 unsigned int flags);

include/linux/socket.h +2 -0

index 421afb4..171b08d 100644
@@ -318,6 +318,8 @@ extern int csum_partial_copy_fromiovecend(unsigned char *kdata,
 
 extern int verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr *address, int mode);
 extern int memcpy_toiovec(struct iovec *v, unsigned char *kdata, int len);
+extern int memcpy_toiovecend(const struct iovec *v, unsigned char *kdata,
+			     int offset, int len);
 extern int move_addr_to_user(struct sockaddr *kaddr, int klen, void __user *uaddr, int __user *ulen);
 extern int move_addr_to_kernel(void __user *uaddr, int ulen, struct sockaddr *kaddr);
 extern int put_cmsg(struct msghdr*, int level, int type, int len, void *data);

net/core/datagram.c +92 -0

98 lines not on this page · raw message

net/core/iovec.c +26 -0

index 4c9c012..a215545 100644
@@ -98,6 +98,31 @@ int memcpy_toiovec(struct iovec *iov, unsigned char *kdata, int len)
 }
 
 /*
+ *	Copy kernel to iovec. Returns -EFAULT on error.
+ */
+
+int memcpy_toiovecend(const struct iovec *iov, unsigned char *kdata,
+		      int offset, int len)
+{
+	int copy;
+	for (; len > 0; ++iov) {
+		/* Skip over the finished iovecs */
+		if (unlikely(offset >= iov->iov_len)) {
+			offset -= iov->iov_len;
+			continue;
+		}
+		copy = min_t(unsigned int, iov->iov_len - offset, len);
+		offset = 0;
+		if (copy_to_user(iov->iov_base, kdata, copy))
+			return -EFAULT;
+		kdata += copy;
+		len -= copy;
+	}
+
+	return 0;
+}
+
+/*
  *	Copy iovec to kernel. Returns -EFAULT on error.
  *
  *	Note: this modifies the original iovec.

@@ -236,3 +261,4 @@ EXPORT_SYMBOL(csum_partial_copy_fromiovecend);
 EXPORT_SYMBOL(memcpy_fromiovec);
 EXPORT_SYMBOL(memcpy_fromiovecend);
 EXPORT_SYMBOL(memcpy_toiovec);
+EXPORT_SYMBOL(memcpy_toiovecend);

Signature · 1 line

1.6.0.6

Michael S. Tsirkin

author

2009-04-20 11:27 UTC #2 lore raw

PATCH 2/3 tun: fix tun_chr_aio_read so that aio works

In reply to a message not in the archive

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

Fix by using the new skb_copy_datagram_const_iovec.

Signed-off-by Michael S. Tsirkin <[email protected]>

---
 drivers/net/tun.c |   11 ++++++-----
 1 files changed, 6 insertions(+), 5 deletions(-)

drivers/net/tun.c +6 -5

index 16716ae..24c19c2 100644
@@ -679,7 +679,7 @@ static ssize_t tun_chr_aio_write(struct kiocb *iocb, const struct iovec *iv,
 /* Put packet to the user space buffer */
 static __inline__ ssize_t tun_put_user(struct tun_struct *tun,
 				       struct sk_buff *skb,
-				       struct iovec *iv, int len)
+				       const struct iovec *iv, int len)
 {
 	struct tun_pi pi = { 0, skb->protocol };
 	ssize_t total = 0;

@@ -693,7 +693,7 @@ static __inline__ ssize_t tun_put_user(struct tun_struct *tun,
 			pi.flags |= TUN_PKT_STRIP;
 		}
 
-		if (memcpy_toiovec(iv, (void *) &pi, sizeof(pi)))
+		if (memcpy_toiovecend(iv, (void *) &pi, 0, sizeof(pi)))
 			return -EFAULT;
 		total += sizeof(pi);
 	}

@@ -726,14 +726,15 @@ static __inline__ ssize_t tun_put_user(struct tun_struct *tun,
 			gso.csum_offset = skb->csum_offset;
 		} /* else everything is zero */
 
-		if (unlikely(memcpy_toiovec(iv, (void *)&gso, sizeof(gso))))
+		if (unlikely(memcpy_toiovecend(iv, (void *)&gso, total,
+					       sizeof(gso))))
 			return -EFAULT;
 		total += sizeof(gso);
 	}
 
 	len = min_t(int, skb->len, len);
 
-	skb_copy_datagram_iovec(skb, 0, iv, len);
+	skb_copy_datagram_const_iovec(skb, 0, iv, total, len);
 	total += len;
 
 	tun->dev->stats.tx_packets++;

@@ -788,7 +789,7 @@ static ssize_t tun_chr_aio_read(struct kiocb *iocb, const struct iovec *iv,
 		}
 		netif_wake_queue(tun->dev);
 
-		ret = tun_put_user(tun, skb, (struct iovec *) iv, len);
+		ret = tun_put_user(tun, skb, iv, len);
 		kfree_skb(skb);
 		break;
 	}

Signature · 1 line

1.6.0.6

Michael S. Tsirkin

author

2009-04-20 11:27 UTC #3 lore raw

PATCH 3/3 tun: fix tun_chr_aio_write so that aio works

In reply to a message not in the archive

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 <[email protected]>

---
 drivers/net/tun.c      |   13 ++++++++-----
 include/linux/skbuff.h |    3 ++-
 include/linux/socket.h |    4 ++--
 net/core/datagram.c    |   20 ++++++++++++++------
 net/core/iovec.c       |    7 ++++---
 5 files changed, 30 insertions(+), 17 deletions(-)

drivers/net/tun.c +8 -5

index 24c19c2..c55be81 100644
@@ -536,31 +536,34 @@ 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) {

@@ -577,7 +580,7 @@ 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;

@@ -669,7 +672,7 @@ 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);

include/linux/skbuff.h +2 -1

index af2b21b..1b5c3d2 100644
@@ -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,

include/linux/socket.h +2 -2

index 171b08d..42a0396 100644
@@ -309,8 +309,8 @@ 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, 
-				int offset, int len);
+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, 
 					  int offset,

net/core/datagram.c +14 -6

index 4dbb05c..914d5fa 100644
@@ -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;
 		}

net/core/iovec.c +4 -3

index a215545..40a76ce 100644
@@ -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) {

Signature · 1 line

1.6.0.6