| Message ID | 1366897638-21882-2-git-send-email-bpoirier@suse.de |
|---|---|
| State | Superseded, archived |
| Delegated to: | David Miller |
| Headers | show |
On Thu, 2013-04-25 at 09:47 -0400, Benjamin Poirier wrote: > Currently, peeking on a unix datagram socket with an offset larger than len of > the data in the sk receive queue returns immediately with bogus data. That's > because *off is not reset between each skb_queue_walk(). > > This patch fixes this so that the behavior is the same as peeking with no > offset on an empty queue: the caller blocks. > > Signed-off-by: Benjamin Poirier <bpoirier@suse.de> > --- > net/core/datagram.c | 25 +++++++++++++++---------- > 1 file changed, 15 insertions(+), 10 deletions(-) > > diff --git a/net/core/datagram.c b/net/core/datagram.c > index 02398ae..6c502b5 100644 > --- a/net/core/datagram.c > +++ b/net/core/datagram.c > @@ -78,9 +78,10 @@ static int receiver_wake_function(wait_queue_t *wait, unsigned int mode, int syn > return autoremove_wake_function(wait, mode, sync, key); > } > /* > - * Wait for a packet.. > + * Wait for the last received packet to be different from skb > */ > -static int wait_for_packet(struct sock *sk, int *err, long *timeo_p) > +static int wait_for_more_packets(struct sock *sk, int *err, long *timeo_p, > + struct sk_buff *skb) const struct sk_buff *skb > { > int error; > DEFINE_WAIT_FUNC(wait, receiver_wake_function); > @@ -92,7 +93,7 @@ static int wait_for_packet(struct sock *sk, int *err, long *timeo_p) > if (error) > goto out_err; > > - if (!skb_queue_empty(&sk->sk_receive_queue)) > + if ((struct sk_buff *)sk->sk_receive_queue.prev != skb) Why is the cast needed ? > goto out; > > /* Socket shut down? */ > @@ -131,9 +132,9 @@ out_noerr: > * __skb_recv_datagram - Receive a datagram skbuff > * @sk: socket > * @flags: MSG_ flags > - * @off: an offset in bytes to peek skb from. Returns an offset > - * within an skb where data actually starts > * @peeked: returns non-zero if this packet has been seen before > + * @_off: an offset in bytes to peek skb from. Returns an offset > + * within an skb where data actually starts > * @err: error code returned > * > * Get a datagram skbuff, understands the peeking, nonblocking wakeups > @@ -159,9 +160,9 @@ out_noerr: > * the standard around please. > */ > struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags, > - int *peeked, int *off, int *err) > + int *peeked, int *_off, int *err) > { > - struct sk_buff *skb; > + struct sk_buff *skb, *last; > long timeo; > /* > * Caller is allowed not to check sk->sk_err before skb_recv_datagram() > @@ -182,13 +183,16 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags, > */ > unsigned long cpu_flags; > struct sk_buff_head *queue = &sk->sk_receive_queue; > + int off = *_off; > > spin_lock_irqsave(&queue->lock, cpu_flags); > + last = (struct sk_buff *)queue; This could be done before spin_lock > skb_queue_walk(queue, skb) { > + last = skb; > *peeked = skb->peeked; > if (flags & MSG_PEEK) { > - if (*off >= skb->len && (skb->len || *off)) { > - *off -= skb->len; > + if (off >= skb->len && (skb->len || off)) { > + off -= skb->len; > continue; > } > skb->peeked = 1; > @@ -197,6 +201,7 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags, > __skb_unlink(skb, queue); > > spin_unlock_irqrestore(&queue->lock, cpu_flags); > + *_off = off; > return skb; > } > spin_unlock_irqrestore(&queue->lock, cpu_flags); > @@ -206,7 +211,7 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags, > if (!timeo) > goto no_packet; > > - } while (!wait_for_packet(sk, err, &timeo)); > + } while (!wait_for_more_packets(sk, err, &timeo, last)); > > return NULL; > Other than that, patch seems fine. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/core/datagram.c b/net/core/datagram.c index 02398ae..6c502b5 100644 --- a/net/core/datagram.c +++ b/net/core/datagram.c @@ -78,9 +78,10 @@ static int receiver_wake_function(wait_queue_t *wait, unsigned int mode, int syn return autoremove_wake_function(wait, mode, sync, key); } /* - * Wait for a packet.. + * Wait for the last received packet to be different from skb */ -static int wait_for_packet(struct sock *sk, int *err, long *timeo_p) +static int wait_for_more_packets(struct sock *sk, int *err, long *timeo_p, + struct sk_buff *skb) { int error; DEFINE_WAIT_FUNC(wait, receiver_wake_function); @@ -92,7 +93,7 @@ static int wait_for_packet(struct sock *sk, int *err, long *timeo_p) if (error) goto out_err; - if (!skb_queue_empty(&sk->sk_receive_queue)) + if ((struct sk_buff *)sk->sk_receive_queue.prev != skb) goto out; /* Socket shut down? */ @@ -131,9 +132,9 @@ out_noerr: * __skb_recv_datagram - Receive a datagram skbuff * @sk: socket * @flags: MSG_ flags - * @off: an offset in bytes to peek skb from. Returns an offset - * within an skb where data actually starts * @peeked: returns non-zero if this packet has been seen before + * @_off: an offset in bytes to peek skb from. Returns an offset + * within an skb where data actually starts * @err: error code returned * * Get a datagram skbuff, understands the peeking, nonblocking wakeups @@ -159,9 +160,9 @@ out_noerr: * the standard around please. */ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags, - int *peeked, int *off, int *err) + int *peeked, int *_off, int *err) { - struct sk_buff *skb; + struct sk_buff *skb, *last; long timeo; /* * Caller is allowed not to check sk->sk_err before skb_recv_datagram() @@ -182,13 +183,16 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags, */ unsigned long cpu_flags; struct sk_buff_head *queue = &sk->sk_receive_queue; + int off = *_off; spin_lock_irqsave(&queue->lock, cpu_flags); + last = (struct sk_buff *)queue; skb_queue_walk(queue, skb) { + last = skb; *peeked = skb->peeked; if (flags & MSG_PEEK) { - if (*off >= skb->len && (skb->len || *off)) { - *off -= skb->len; + if (off >= skb->len && (skb->len || off)) { + off -= skb->len; continue; } skb->peeked = 1; @@ -197,6 +201,7 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags, __skb_unlink(skb, queue); spin_unlock_irqrestore(&queue->lock, cpu_flags); + *_off = off; return skb; } spin_unlock_irqrestore(&queue->lock, cpu_flags); @@ -206,7 +211,7 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags, if (!timeo) goto no_packet; - } while (!wait_for_packet(sk, err, &timeo)); + } while (!wait_for_more_packets(sk, err, &timeo, last)); return NULL;
Currently, peeking on a unix datagram socket with an offset larger than len of the data in the sk receive queue returns immediately with bogus data. That's because *off is not reset between each skb_queue_walk(). This patch fixes this so that the behavior is the same as peeking with no offset on an empty queue: the caller blocks. Signed-off-by: Benjamin Poirier <bpoirier@suse.de> --- net/core/datagram.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-)