From fec846fa7eddf7bb651bf88bd78c7db1410ae3b1 Mon Sep 17 00:00:00 2001 From: Nicolas Maier Date: Sat, 20 Jan 2024 09:10:18 +0100 Subject: [PATCH] can: bcm: add recvmsg flags for own, local and remote traffic CAN RAW sockets allow userspace to tell if a received CAN frame comes from the same socket, another socket on the same host, or another host. See commit 1e55659ce6dd ("can-raw: add msg_flags to distinguish local traffic"). However, this feature is missing in CAN BCM sockets. Add the same feature to CAN BCM sockets. When reading a received frame (opcode RX_CHANGED) using recvmsg, two flags in msg->msg_flags may be set following the previous convention (from CAN RAW), to distinguish between 'own', 'local' and 'remote' CAN traffic. Update the documentation to reflect this change. Signed-off-by: Nicolas Maier Signed-off-by: Oliver Hartkopp Link: https://lore.kernel.org/all/20240120081018.2319-1-socketcan@hartkopp.net Signed-off-by: Marc Kleine-Budde --- Documentation/networking/can.rst | 34 ++++++++-------- net/can/bcm.c | 69 ++++++++++++++++++++++++++------ 2 files changed, 75 insertions(+), 28 deletions(-) diff --git a/Documentation/networking/can.rst b/Documentation/networking/can.rst index d7e1ada905b2..62519d38c58b 100644 --- a/Documentation/networking/can.rst +++ b/Documentation/networking/can.rst @@ -444,6 +444,24 @@ definitions are specified for CAN specific MTUs in include/linux/can.h: #define CANFD_MTU (sizeof(struct canfd_frame)) == 72 => CAN FD frame +Returned Message Flags +---------------------- + +When using the system call recvmsg(2) on a RAW or a BCM socket, the +msg->msg_flags field may contain the following flags: + +MSG_DONTROUTE: + set when the received frame was created on the local host. + +MSG_CONFIRM: + set when the frame was sent via the socket it is received on. + This flag can be interpreted as a 'transmission confirmation' when the + CAN driver supports the echo of frames on driver level, see + :ref:`socketcan-local-loopback1` and :ref:`socketcan-local-loopback2`. + (Note: In order to receive such messages on a RAW socket, + CAN_RAW_RECV_OWN_MSGS must be set.) + + .. _socketcan-raw-sockets: RAW Protocol Sockets with can_filters (SOCK_RAW) @@ -693,22 +711,6 @@ where the CAN_INV_FILTER flag is set in order to notch single CAN IDs or CAN ID ranges from the incoming traffic. -RAW Socket Returned Message Flags -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -When using recvmsg() call, the msg->msg_flags may contain following flags: - -MSG_DONTROUTE: - set when the received frame was created on the local host. - -MSG_CONFIRM: - set when the frame was sent via the socket it is received on. - This flag can be interpreted as a 'transmission confirmation' when the - CAN driver supports the echo of frames on driver level, see - :ref:`socketcan-local-loopback1` and :ref:`socketcan-local-loopback2`. - In order to receive such messages, CAN_RAW_RECV_OWN_MSGS must be set. - - Broadcast Manager Protocol Sockets (SOCK_DGRAM) ----------------------------------------------- diff --git a/net/can/bcm.c b/net/can/bcm.c index 9168114fc87f..27d5fcf0eac9 100644 --- a/net/can/bcm.c +++ b/net/can/bcm.c @@ -72,9 +72,11 @@ #define BCM_TIMER_SEC_MAX (400 * 24 * 60 * 60) /* use of last_frames[index].flags */ +#define RX_LOCAL 0x10 /* frame was created on the local host */ +#define RX_OWN 0x20 /* frame was sent via the socket it was received on */ #define RX_RECV 0x40 /* received data for this element */ #define RX_THR 0x80 /* element not been sent due to throttle feature */ -#define BCM_CAN_FLAGS_MASK 0x3F /* to clean private flags after usage */ +#define BCM_CAN_FLAGS_MASK 0x0F /* to clean private flags after usage */ /* get best masking value for can_rx_register() for a given single can_id */ #define REGMASK(id) ((id & CAN_EFF_FLAG) ? \ @@ -138,6 +140,16 @@ static LIST_HEAD(bcm_notifier_list); static DEFINE_SPINLOCK(bcm_notifier_lock); static struct bcm_sock *bcm_busy_notifier; +/* Return pointer to store the extra msg flags for bcm_recvmsg(). + * We use the space of one unsigned int beyond the 'struct sockaddr_can' + * in skb->cb. + */ +static inline unsigned int *bcm_flags(struct sk_buff *skb) +{ + /* return pointer after struct sockaddr_can */ + return (unsigned int *)(&((struct sockaddr_can *)skb->cb)[1]); +} + static inline struct bcm_sock *bcm_sk(const struct sock *sk) { return (struct bcm_sock *)sk; @@ -325,6 +337,7 @@ static void bcm_send_to_user(struct bcm_op *op, struct bcm_msg_head *head, struct sock *sk = op->sk; unsigned int datalen = head->nframes * op->cfsiz; int err; + unsigned int *pflags; skb = alloc_skb(sizeof(*head) + datalen, gfp_any()); if (!skb) @@ -332,6 +345,14 @@ static void bcm_send_to_user(struct bcm_op *op, struct bcm_msg_head *head, skb_put_data(skb, head, sizeof(*head)); + /* ensure space for sockaddr_can and msg flags */ + sock_skb_cb_check_size(sizeof(struct sockaddr_can) + + sizeof(unsigned int)); + + /* initialize msg flags */ + pflags = bcm_flags(skb); + *pflags = 0; + if (head->nframes) { /* CAN frames starting here */ firstframe = (struct canfd_frame *)skb_tail_pointer(skb); @@ -344,8 +365,14 @@ static void bcm_send_to_user(struct bcm_op *op, struct bcm_msg_head *head, * relevant for updates that are generated by the * BCM, where nframes is 1 */ - if (head->nframes == 1) + if (head->nframes == 1) { + if (firstframe->flags & RX_LOCAL) + *pflags |= MSG_DONTROUTE; + if (firstframe->flags & RX_OWN) + *pflags |= MSG_CONFIRM; + firstframe->flags &= BCM_CAN_FLAGS_MASK; + } } if (has_timestamp) { @@ -360,7 +387,6 @@ static void bcm_send_to_user(struct bcm_op *op, struct bcm_msg_head *head, * containing the interface index. */ - sock_skb_cb_check_size(sizeof(struct sockaddr_can)); addr = (struct sockaddr_can *)skb->cb; memset(addr, 0, sizeof(*addr)); addr->can_family = AF_CAN; @@ -444,7 +470,7 @@ static void bcm_rx_changed(struct bcm_op *op, struct canfd_frame *data) op->frames_filtered = op->frames_abs = 0; /* this element is not throttled anymore */ - data->flags &= (BCM_CAN_FLAGS_MASK|RX_RECV); + data->flags &= ~RX_THR; memset(&head, 0, sizeof(head)); head.opcode = RX_CHANGED; @@ -465,13 +491,17 @@ static void bcm_rx_changed(struct bcm_op *op, struct canfd_frame *data) */ static void bcm_rx_update_and_send(struct bcm_op *op, struct canfd_frame *lastdata, - const struct canfd_frame *rxdata) + const struct canfd_frame *rxdata, + unsigned char traffic_flags) { memcpy(lastdata, rxdata, op->cfsiz); /* mark as used and throttled by default */ lastdata->flags |= (RX_RECV|RX_THR); + /* add own/local/remote traffic flags */ + lastdata->flags |= traffic_flags; + /* throttling mode inactive ? */ if (!op->kt_ival2) { /* send RX_CHANGED to the user immediately */ @@ -508,7 +538,8 @@ rx_changed_settime: * received data stored in op->last_frames[] */ static void bcm_rx_cmp_to_index(struct bcm_op *op, unsigned int index, - const struct canfd_frame *rxdata) + const struct canfd_frame *rxdata, + unsigned char traffic_flags) { struct canfd_frame *cf = op->frames + op->cfsiz * index; struct canfd_frame *lcf = op->last_frames + op->cfsiz * index; @@ -521,7 +552,7 @@ static void bcm_rx_cmp_to_index(struct bcm_op *op, unsigned int index, if (!(lcf->flags & RX_RECV)) { /* received data for the first time => send update to user */ - bcm_rx_update_and_send(op, lcf, rxdata); + bcm_rx_update_and_send(op, lcf, rxdata, traffic_flags); return; } @@ -529,7 +560,7 @@ static void bcm_rx_cmp_to_index(struct bcm_op *op, unsigned int index, for (i = 0; i < rxdata->len; i += 8) { if ((get_u64(cf, i) & get_u64(rxdata, i)) != (get_u64(cf, i) & get_u64(lcf, i))) { - bcm_rx_update_and_send(op, lcf, rxdata); + bcm_rx_update_and_send(op, lcf, rxdata, traffic_flags); return; } } @@ -537,7 +568,7 @@ static void bcm_rx_cmp_to_index(struct bcm_op *op, unsigned int index, if (op->flags & RX_CHECK_DLC) { /* do a real check in CAN frame length */ if (rxdata->len != lcf->len) { - bcm_rx_update_and_send(op, lcf, rxdata); + bcm_rx_update_and_send(op, lcf, rxdata, traffic_flags); return; } } @@ -644,6 +675,7 @@ static void bcm_rx_handler(struct sk_buff *skb, void *data) struct bcm_op *op = (struct bcm_op *)data; const struct canfd_frame *rxframe = (struct canfd_frame *)skb->data; unsigned int i; + unsigned char traffic_flags; if (op->can_id != rxframe->can_id) return; @@ -673,15 +705,24 @@ static void bcm_rx_handler(struct sk_buff *skb, void *data) return; } + /* compute flags to distinguish between own/local/remote CAN traffic */ + traffic_flags = 0; + if (skb->sk) { + traffic_flags |= RX_LOCAL; + if (skb->sk == op->sk) + traffic_flags |= RX_OWN; + } + if (op->flags & RX_FILTER_ID) { /* the easiest case */ - bcm_rx_update_and_send(op, op->last_frames, rxframe); + bcm_rx_update_and_send(op, op->last_frames, rxframe, + traffic_flags); goto rx_starttimer; } if (op->nframes == 1) { /* simple compare with index 0 */ - bcm_rx_cmp_to_index(op, 0, rxframe); + bcm_rx_cmp_to_index(op, 0, rxframe, traffic_flags); goto rx_starttimer; } @@ -698,7 +739,8 @@ static void bcm_rx_handler(struct sk_buff *skb, void *data) if ((get_u64(op->frames, 0) & get_u64(rxframe, 0)) == (get_u64(op->frames, 0) & get_u64(op->frames + op->cfsiz * i, 0))) { - bcm_rx_cmp_to_index(op, i, rxframe); + bcm_rx_cmp_to_index(op, i, rxframe, + traffic_flags); break; } } @@ -1675,6 +1717,9 @@ static int bcm_recvmsg(struct socket *sock, struct msghdr *msg, size_t size, memcpy(msg->msg_name, skb->cb, msg->msg_namelen); } + /* assign the flags that have been recorded in bcm_send_to_user() */ + msg->msg_flags |= *(bcm_flags(skb)); + skb_free_datagram(sk, skb); return size;