Re: [PATCH v2 1/2] can: add support for filtering own messages only

[Oliver Hartkopp <socketcan@hartkopp.net>]

Hi Erik,

IMO putting linux-can@vger.kernel.org in CC would be sufficient in this 
stage of discussion.

On 04.05.21 22:35, Erik Flodin wrote:
> Add a new flag to can_rx_register/unregister that, when set, requires
> that the received sk_buff's owning socket matches the socket pointer
> given when setting the filter. This makes it possible to set a filter
> that matches all frames sent on a given socket and nothing else.

This is a pretty simple requirement and you are touching almost every 
CAN network layer file.

 From this description I would suggest a two-liner to be added in raw.c

diff --git a/net/can/raw.c b/net/can/raw.c
index 139d9471ddcf..8c6371a0c8a6 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -123,10 +123,14 @@ static void raw_rcv(struct sk_buff *oskb, void *data)

         /* check the received tx sock reference */
         if (!ro->recv_own_msgs && oskb->sk == sk)
                 return;

+       /* check the received tx sock reference */
+       if (ro->recv_only_own_msgs && oskb->sk != sk)
+               return;
+
         /* do not pass non-CAN2.0 frames to a legacy socket */
         if (!ro->fd_frames && oskb->len != CAN_MTU)
                 return;

         /* eliminate multiple filter matches for the same skb */


And then add CAN_RAW_RECV_ONLY_OWN_MSGS accordingly.

Wouldn't that already match your requirements?

Best regards,
Oliver

ps. please reduce the CC receipient list before answering, thanks.

> 
> Signed-off-by: Erik Flodin <erik@flodin.me>
> ---
>   include/linux/can/core.h |  4 ++--
>   net/can/af_can.c         | 50 ++++++++++++++++++++++------------------
>   net/can/af_can.h         |  1 +
>   net/can/bcm.c            |  9 +++++---
>   net/can/gw.c             |  7 +++---
>   net/can/isotp.c          |  8 +++----
>   net/can/j1939/main.c     |  4 ++--
>   net/can/proc.c           | 11 +++++----
>   net/can/raw.c            | 10 ++++----
>   9 files changed, 58 insertions(+), 46 deletions(-)
> 
> diff --git a/include/linux/can/core.h b/include/linux/can/core.h
> index 5fb8d0e3f9c1..7ee68128dc10 100644
> --- a/include/linux/can/core.h
> +++ b/include/linux/can/core.h
> @@ -48,12 +48,12 @@ extern int  can_proto_register(const struct can_proto *cp);
>   extern void can_proto_unregister(const struct can_proto *cp);
>   
>   int can_rx_register(struct net *net, struct net_device *dev,
> -		    canid_t can_id, canid_t mask,
> +		    canid_t can_id, canid_t mask, bool match_sk,
>   		    void (*func)(struct sk_buff *, void *),
>   		    void *data, char *ident, struct sock *sk);
>   
>   extern void can_rx_unregister(struct net *net, struct net_device *dev,
> -			      canid_t can_id, canid_t mask,
> +			      canid_t can_id, canid_t mask, bool match_sk,
>   			      void (*func)(struct sk_buff *, void *),
>   			      void *data);
>   
> diff --git a/net/can/af_can.c b/net/can/af_can.c
> index cce2af10eb3e..7b639c121653 100644
> --- a/net/can/af_can.c
> +++ b/net/can/af_can.c
> @@ -414,6 +414,7 @@ static struct hlist_head *can_rcv_list_find(canid_t *can_id, canid_t *mask,
>    * @dev: pointer to netdevice (NULL => subscribe from 'all' CAN devices list)
>    * @can_id: CAN identifier (see description)
>    * @mask: CAN mask (see description)
> + * @match_sk: match socket pointer on received sk_buff (see description)
>    * @func: callback function on filter match
>    * @data: returned parameter for callback function
>    * @ident: string for calling module identification
> @@ -428,6 +429,9 @@ static struct hlist_head *can_rcv_list_find(canid_t *can_id, canid_t *mask,
>    *  The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
>    *  filter for error message frames (CAN_ERR_FLAG bit set in mask).
>    *
> + *  If match_sk is true, the received sk_buff's owning socket must also match
> + *  the given socket pointer.
> + *
>    *  The provided pointer to the sk_buff is guaranteed to be valid as long as
>    *  the callback function is running. The callback function must *not* free
>    *  the given sk_buff while processing it's task. When the given sk_buff is
> @@ -440,8 +444,9 @@ static struct hlist_head *can_rcv_list_find(canid_t *can_id, canid_t *mask,
>    *  -ENODEV unknown device
>    */
>   int can_rx_register(struct net *net, struct net_device *dev, canid_t can_id,
> -		    canid_t mask, void (*func)(struct sk_buff *, void *),
> -		    void *data, char *ident, struct sock *sk)
> +		    canid_t mask, bool match_sk,
> +		    void (*func)(struct sk_buff *, void *), void *data,
> +		    char *ident, struct sock *sk)
>   {
>   	struct receiver *rcv;
>   	struct hlist_head *rcv_list;
> @@ -468,6 +473,7 @@ int can_rx_register(struct net *net, struct net_device *dev, canid_t can_id,
>   
>   	rcv->can_id = can_id;
>   	rcv->mask = mask;
> +	rcv->match_sk = match_sk;
>   	rcv->matches = 0;
>   	rcv->func = func;
>   	rcv->data = data;
> @@ -503,6 +509,7 @@ static void can_rx_delete_receiver(struct rcu_head *rp)
>    * @dev: pointer to netdevice (NULL => unsubscribe from 'all' CAN devices list)
>    * @can_id: CAN identifier
>    * @mask: CAN mask
> + * @match_sk: match socket pointer on received sk_buff
>    * @func: callback function on filter match
>    * @data: returned parameter for callback function
>    *
> @@ -510,8 +517,8 @@ static void can_rx_delete_receiver(struct rcu_head *rp)
>    *  Removes subscription entry depending on given (subscription) values.
>    */
>   void can_rx_unregister(struct net *net, struct net_device *dev, canid_t can_id,
> -		       canid_t mask, void (*func)(struct sk_buff *, void *),
> -		       void *data)
> +		       canid_t mask, bool match_sk,
> +		       void (*func)(struct sk_buff *, void *), void *data)
>   {
>   	struct receiver *rcv = NULL;
>   	struct hlist_head *rcv_list;
> @@ -535,7 +542,8 @@ void can_rx_unregister(struct net *net, struct net_device *dev, canid_t can_id,
>   	 */
>   	hlist_for_each_entry_rcu(rcv, rcv_list, list) {
>   		if (rcv->can_id == can_id && rcv->mask == mask &&
> -		    rcv->func == func && rcv->data == data)
> +		    rcv->match_sk == match_sk && rcv->func == func &&
> +		    rcv->data == data)
>   			break;
>   	}
>   
> @@ -546,8 +554,8 @@ void can_rx_unregister(struct net *net, struct net_device *dev, canid_t can_id,
>   	 * a warning here.
>   	 */
>   	if (!rcv) {
> -		pr_warn("can: receive list entry not found for dev %s, id %03X, mask %03X\n",
> -			DNAME(dev), can_id, mask);
> +		pr_warn("can: receive list entry not found for dev %s, id %03X, mask %03X%s\n",
> +			DNAME(dev), can_id, mask, match_sk ? " (match sk)" : "");
>   		goto out;
>   	}
>   
> @@ -569,10 +577,14 @@ void can_rx_unregister(struct net *net, struct net_device *dev, canid_t can_id,
>   }
>   EXPORT_SYMBOL(can_rx_unregister);
>   
> -static inline void deliver(struct sk_buff *skb, struct receiver *rcv)
> +static inline int deliver(struct sk_buff *skb, struct receiver *rcv)
>   {
> -	rcv->func(skb, rcv->data);
> -	rcv->matches++;
> +	if (!rcv->match_sk || skb->sk == rcv->sk) {
> +		rcv->func(skb, rcv->data);
> +		rcv->matches++;
> +		return 1;
> +	}
> +	return 0;
>   }
>   
>   static int can_rcv_filter(struct can_dev_rcv_lists *dev_rcv_lists, struct sk_buff *skb)
> @@ -589,8 +601,7 @@ static int can_rcv_filter(struct can_dev_rcv_lists *dev_rcv_lists, struct sk_buf
>   		/* check for error message frame entries only */
>   		hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_ERR], list) {
>   			if (can_id & rcv->mask) {
> -				deliver(skb, rcv);
> -				matches++;
> +				matches += deliver(skb, rcv);
>   			}
>   		}
>   		return matches;
> @@ -598,23 +609,20 @@ static int can_rcv_filter(struct can_dev_rcv_lists *dev_rcv_lists, struct sk_buf
>   
>   	/* check for unfiltered entries */
>   	hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_ALL], list) {
> -		deliver(skb, rcv);
> -		matches++;
> +		matches += deliver(skb, rcv);
>   	}
>   
>   	/* check for can_id/mask entries */
>   	hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_FIL], list) {
>   		if ((can_id & rcv->mask) == rcv->can_id) {
> -			deliver(skb, rcv);
> -			matches++;
> +			matches += deliver(skb, rcv);
>   		}
>   	}
>   
>   	/* check for inverted can_id/mask entries */
>   	hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_INV], list) {
>   		if ((can_id & rcv->mask) != rcv->can_id) {
> -			deliver(skb, rcv);
> -			matches++;
> +			matches += deliver(skb, rcv);
>   		}
>   	}
>   
> @@ -625,15 +633,13 @@ static int can_rcv_filter(struct can_dev_rcv_lists *dev_rcv_lists, struct sk_buf
>   	if (can_id & CAN_EFF_FLAG) {
>   		hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx_eff[effhash(can_id)], list) {
>   			if (rcv->can_id == can_id) {
> -				deliver(skb, rcv);
> -				matches++;
> +				matches += deliver(skb, rcv);
>   			}
>   		}
>   	} else {
>   		can_id &= CAN_SFF_MASK;
>   		hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx_sff[can_id], list) {
> -			deliver(skb, rcv);
> -			matches++;
> +			matches += deliver(skb, rcv);
>   		}
>   	}
>   
> diff --git a/net/can/af_can.h b/net/can/af_can.h
> index 7c2d9161e224..ea98b10d93e7 100644
> --- a/net/can/af_can.h
> +++ b/net/can/af_can.h
> @@ -52,6 +52,7 @@ struct receiver {
>   	struct hlist_node list;
>   	canid_t can_id;
>   	canid_t mask;
> +	bool match_sk;
>   	unsigned long matches;
>   	void (*func)(struct sk_buff *skb, void *data);
>   	void *data;
> diff --git a/net/can/bcm.c b/net/can/bcm.c
> index 909b9e684e04..d89dd82c2178 100644
> --- a/net/can/bcm.c
> +++ b/net/can/bcm.c
> @@ -729,7 +729,8 @@ static void bcm_rx_unreg(struct net_device *dev, struct bcm_op *op)
>   {
>   	if (op->rx_reg_dev == dev) {
>   		can_rx_unregister(dev_net(dev), dev, op->can_id,
> -				  REGMASK(op->can_id), bcm_rx_handler, op);
> +				  REGMASK(op->can_id), false, bcm_rx_handler,
> +				  op);
>   
>   		/* mark as removed subscription */
>   		op->rx_reg_dev = NULL;
> @@ -775,6 +776,7 @@ static int bcm_delete_rx_op(struct list_head *ops, struct bcm_msg_head *mh,
>   				can_rx_unregister(sock_net(op->sk), NULL,
>   						  op->can_id,
>   						  REGMASK(op->can_id),
> +						  false,
>   						  bcm_rx_handler, op);
>   
>   			list_del(&op->list);
> @@ -1193,6 +1195,7 @@ static int bcm_rx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
>   				err = can_rx_register(sock_net(sk), dev,
>   						      op->can_id,
>   						      REGMASK(op->can_id),
> +						      false,
>   						      bcm_rx_handler, op,
>   						      "bcm", sk);
>   
> @@ -1202,7 +1205,7 @@ static int bcm_rx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
>   
>   		} else
>   			err = can_rx_register(sock_net(sk), NULL, op->can_id,
> -					      REGMASK(op->can_id),
> +					      REGMASK(op->can_id), false,
>   					      bcm_rx_handler, op, "bcm", sk);
>   		if (err) {
>   			/* this bcm rx op is broken -> remove it */
> @@ -1500,7 +1503,7 @@ static int bcm_release(struct socket *sock)
>   			}
>   		} else
>   			can_rx_unregister(net, NULL, op->can_id,
> -					  REGMASK(op->can_id),
> +					  REGMASK(op->can_id), false,
>   					  bcm_rx_handler, op);
>   
>   		bcm_remove_op(op);
> diff --git a/net/can/gw.c b/net/can/gw.c
> index ba4124805602..5dbc7b85e0fc 100644
> --- a/net/can/gw.c
> +++ b/net/can/gw.c
> @@ -567,14 +567,15 @@ static void can_can_gw_rcv(struct sk_buff *skb, void *data)
>   static inline int cgw_register_filter(struct net *net, struct cgw_job *gwj)
>   {
>   	return can_rx_register(net, gwj->src.dev, gwj->ccgw.filter.can_id,
> -			       gwj->ccgw.filter.can_mask, can_can_gw_rcv,
> -			       gwj, "gw", NULL);
> +			       gwj->ccgw.filter.can_mask, false,
> +			       can_can_gw_rcv, gwj, "gw", NULL);
>   }
>   
>   static inline void cgw_unregister_filter(struct net *net, struct cgw_job *gwj)
>   {
>   	can_rx_unregister(net, gwj->src.dev, gwj->ccgw.filter.can_id,
> -			  gwj->ccgw.filter.can_mask, can_can_gw_rcv, gwj);
> +			  gwj->ccgw.filter.can_mask, false, can_can_gw_rcv,
> +			  gwj);
>   }
>   
>   static int cgw_notifier(struct notifier_block *nb,
> diff --git a/net/can/isotp.c b/net/can/isotp.c
> index 9f94ad3caee9..44d943bbe0b1 100644
> --- a/net/can/isotp.c
> +++ b/net/can/isotp.c
> @@ -1029,7 +1029,7 @@ static int isotp_release(struct socket *sock)
>   			if (dev) {
>   				can_rx_unregister(net, dev, so->rxid,
>   						  SINGLE_MASK(so->rxid),
> -						  isotp_rcv, sk);
> +						  false, isotp_rcv, sk);
>   				dev_put(dev);
>   			}
>   		}
> @@ -1111,7 +1111,7 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
>   	if (do_rx_reg)
>   		can_rx_register(net, dev, addr->can_addr.tp.rx_id,
>   				SINGLE_MASK(addr->can_addr.tp.rx_id),
> -				isotp_rcv, sk, "isotp", sk);
> +				false, isotp_rcv, sk, "isotp", sk);
>   
>   	dev_put(dev);
>   
> @@ -1122,7 +1122,7 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
>   			if (dev) {
>   				can_rx_unregister(net, dev, so->rxid,
>   						  SINGLE_MASK(so->rxid),
> -						  isotp_rcv, sk);
> +						  false, isotp_rcv, sk);
>   				dev_put(dev);
>   			}
>   		}
> @@ -1323,7 +1323,7 @@ static int isotp_notifier(struct notifier_block *nb, unsigned long msg,
>   		if (so->bound && (!(so->opt.flags & CAN_ISOTP_SF_BROADCAST)))
>   			can_rx_unregister(dev_net(dev), dev, so->rxid,
>   					  SINGLE_MASK(so->rxid),
> -					  isotp_rcv, sk);
> +					  false, isotp_rcv, sk);
>   
>   		so->ifindex = 0;
>   		so->bound  = 0;
> diff --git a/net/can/j1939/main.c b/net/can/j1939/main.c
> index da3a7a7bcff2..466a20c76fb6 100644
> --- a/net/can/j1939/main.c
> +++ b/net/can/j1939/main.c
> @@ -177,7 +177,7 @@ static int j1939_can_rx_register(struct j1939_priv *priv)
>   
>   	j1939_priv_get(priv);
>   	ret = can_rx_register(dev_net(ndev), ndev, J1939_CAN_ID, J1939_CAN_MASK,
> -			      j1939_can_recv, priv, "j1939", NULL);
> +			      false, j1939_can_recv, priv, "j1939", NULL);
>   	if (ret < 0) {
>   		j1939_priv_put(priv);
>   		return ret;
> @@ -191,7 +191,7 @@ static void j1939_can_rx_unregister(struct j1939_priv *priv)
>   	struct net_device *ndev = priv->ndev;
>   
>   	can_rx_unregister(dev_net(ndev), ndev, J1939_CAN_ID, J1939_CAN_MASK,
> -			  j1939_can_recv, priv);
> +			  false, j1939_can_recv, priv);
>   
>   	j1939_priv_put(priv);
>   }
> diff --git a/net/can/proc.c b/net/can/proc.c
> index d1fe49e6f16d..d312077832a6 100644
> --- a/net/can/proc.c
> +++ b/net/can/proc.c
> @@ -191,11 +191,12 @@ static void can_print_rcvlist(struct seq_file *m, struct hlist_head *rx_list,
>   
>   	hlist_for_each_entry_rcu(r, rx_list, list) {
>   		char *fmt = (r->can_id & CAN_EFF_FLAG)?
> -			"   %-5s  %08x  %08x  %pK  %pK  %8ld  %s\n" :
> -			"   %-5s     %03x    %08x  %pK  %pK  %8ld  %s\n";
> +			"   %-5s  %08x  %08x   %c   %pK  %pK  %8ld  %s\n" :
> +			"   %-5s     %03x    %08x   %c   %pK  %pK  %8ld  %s\n";
>   
>   		seq_printf(m, fmt, DNAME(dev), r->can_id, r->mask,
> -				r->func, r->data, r->matches, r->ident);
> +				r->match_sk ? '*' : ' ', r->func, r->data,
> +				r->matches, r->ident);
>   	}
>   }
>   
> @@ -206,9 +207,9 @@ static void can_print_recv_banner(struct seq_file *m)
>   	 *                 .......          0  tp20
>   	 */
>   	if (IS_ENABLED(CONFIG_64BIT))
> -		seq_puts(m, "  device   can_id   can_mask      function          userdata       matches  ident\n");
> +		seq_puts(m, "  device   can_id   can_mask  own      function          userdata       matches  ident\n");
>   	else
> -		seq_puts(m, "  device   can_id   can_mask  function  userdata   matches  ident\n");
> +		seq_puts(m, "  device   can_id   can_mask  own  function  userdata   matches  ident\n");
>   }
>   
>   static int can_stats_proc_show(struct seq_file *m, void *v)
> diff --git a/net/can/raw.c b/net/can/raw.c
> index 139d9471ddcf..acfbae28d451 100644
> --- a/net/can/raw.c
> +++ b/net/can/raw.c
> @@ -187,13 +187,13 @@ static int raw_enable_filters(struct net *net, struct net_device *dev,
>   
>   	for (i = 0; i < count; i++) {
>   		err = can_rx_register(net, dev, filter[i].can_id,
> -				      filter[i].can_mask,
> +				      filter[i].can_mask, false,
>   				      raw_rcv, sk, "raw", sk);
>   		if (err) {
>   			/* clean up successfully registered filters */
>   			while (--i >= 0)
>   				can_rx_unregister(net, dev, filter[i].can_id,
> -						  filter[i].can_mask,
> +						  filter[i].can_mask, false,
>   						  raw_rcv, sk);
>   			break;
>   		}
> @@ -209,7 +209,7 @@ static int raw_enable_errfilter(struct net *net, struct net_device *dev,
>   
>   	if (err_mask)
>   		err = can_rx_register(net, dev, 0, err_mask | CAN_ERR_FLAG,
> -				      raw_rcv, sk, "raw", sk);
> +				      false, raw_rcv, sk, "raw", sk);
>   
>   	return err;
>   }
> @@ -222,7 +222,7 @@ static void raw_disable_filters(struct net *net, struct net_device *dev,
>   
>   	for (i = 0; i < count; i++)
>   		can_rx_unregister(net, dev, filter[i].can_id,
> -				  filter[i].can_mask, raw_rcv, sk);
> +				  filter[i].can_mask, false, raw_rcv, sk);
>   }
>   
>   static inline void raw_disable_errfilter(struct net *net,
> @@ -233,7 +233,7 @@ static inline void raw_disable_errfilter(struct net *net,
>   {
>   	if (err_mask)
>   		can_rx_unregister(net, dev, 0, err_mask | CAN_ERR_FLAG,
> -				  raw_rcv, sk);
> +				  false, raw_rcv, sk);
>   }
>   
>   static inline void raw_disable_allfilters(struct net *net,
>