On Wed, 5 May 2021 at 11:15, Oliver Hartkopp <socketcan@xxxxxxxxxxxx> wrote:
> On 05.05.21 10:37, 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.
> >>
>
> (..)
>
> >>
> >> Wouldn't that already match your requirements?
> >
> > I guess that would require me to use two sockets: one for sending
> > (with RECV_ONLY_OWN_MSGS set) and one for receiving. The problem might
> > then be how to avoid the second socket seeing the frames sent from the
> > first, without disabling loopback completly?
>
> This is indeed a question of the application layout.
>
> From what I understood your main requirement is to double check the
> outgoing traffic whether is has been sent.
What I would like to have is:
1. Be notified when a frame has been sent. I send (from user space) a
single frame and wait until I get confirmation before sending the next
to give other nodes on the bus a slot to start sending, even if their
frames have ID with lower priority.
2. I don't want to receive my own frames, except to support the use
case above. But then the kernel tells me that it's mine and I can
easily ignore it.
3. Both be able to run with receive filters set (when that makes
sense) or use the default catch-all filter in cases where I want to
receive everything and don't want to enumerate all possible CAN IDs.
4. Be able to use cansend and candump on the same host as above.
> To me it makes sense to use a
> separate socket for sending that triggers the special handling of send
> acknowledges when receiving frames (on that sending socket).
>
> And then use a separate socket to receive frames needed by the application.
To be able to use two sockets I would have to perform filtering in
user space as well in order to filter out frames sent on one socket
and received on the other. But for how long should I remember the sent
frame to be able to filter it out? It might not come at all (in the
case where there are filters set) and setting a time after which it is
forgotten, even if synchronized with the confirmation on the sending
socket, just doesn't feel rock solid.
> In both cases (even with your one-socket solution) you need to implement
> some more or less complex dispatching in user space when receiving frames.
What I do now is to keep the last sent frame around and when I get a
frame with MSG_CONFIRM set I can check that it's the one I sent,
ignore it and continue sending the next frame (if any).
// Erik
> >>>
> >>> Signed-off-by: Erik Flodin <erik@xxxxxxxxx>
> >>> ---
> >>> 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,
> >>>
