From a5581ef4c2eac6449188862e903eb46c7233582a Mon Sep 17 00:00:00 2001 From: Oliver Hartkopp Date: Wed, 1 Apr 2015 07:50:29 +0200 Subject: [PATCH] can: introduce new raw socket option to join the given CAN filters The CAN_RAW socket can set multiple CAN identifier specific filters that lead to multiple filters in the af_can.c filter processing. These filters are indenpendent from each other which leads to logical OR'ed filters when applied. This socket option joines the given CAN filters in the way that only CAN frames are passed to user space that matched *all* given CAN filters. The semantic for the applied filters is therefore changed to a logical AND. This is useful especially when the filterset is a combination of filters where the CAN_INV_FILTER flag is set in order to notch single CAN IDs or CAN ID ranges from the incoming traffic. As the raw_rcv() function is executed from NET_RX softirq the introduced variables are implemented as per-CPU variables to avoid extensive locking at CAN frame reception time. Signed-off-by: Oliver Hartkopp Signed-off-by: Marc Kleine-Budde --- Documentation/networking/can.txt | 20 ++++++++++++++++++-- include/uapi/linux/can/raw.h | 1 + net/can/raw.c | 31 ++++++++++++++++++++++++++++++- 3 files changed, 49 insertions(+), 3 deletions(-) diff --git a/Documentation/networking/can.txt b/Documentation/networking/can.txt index 0a2859a8ee7e..5abad1e921ca 100644 --- a/Documentation/networking/can.txt +++ b/Documentation/networking/can.txt @@ -22,7 +22,8 @@ This file contains 4.1.3 RAW socket option CAN_RAW_LOOPBACK 4.1.4 RAW socket option CAN_RAW_RECV_OWN_MSGS 4.1.5 RAW socket option CAN_RAW_FD_FRAMES - 4.1.6 RAW socket returned message flags + 4.1.6 RAW socket option CAN_RAW_JOIN_FILTERS + 4.1.7 RAW socket returned message flags 4.2 Broadcast Manager protocol sockets (SOCK_DGRAM) 4.2.1 Broadcast Manager operations 4.2.2 Broadcast Manager message flags @@ -601,7 +602,22 @@ solution for a couple of reasons: CAN FD frames by checking if the device maximum transfer unit is CANFD_MTU. The CAN device MTU can be retrieved e.g. with a SIOCGIFMTU ioctl() syscall. - 4.1.6 RAW socket returned message flags + 4.1.6 RAW socket option CAN_RAW_JOIN_FILTERS + + The CAN_RAW socket can set multiple CAN identifier specific filters that + lead to multiple filters in the af_can.c filter processing. These filters + are indenpendent from each other which leads to logical OR'ed filters when + applied (see 4.1.1). + + This socket option joines the given CAN filters in the way that only CAN + frames are passed to user space that matched *all* given CAN filters. The + semantic for the applied filters is therefore changed to a logical AND. + + This is useful especially when the filterset is a combination of filters + where the CAN_INV_FILTER flag is set in order to notch single CAN IDs or + CAN ID ranges from the incoming traffic. + + 4.1.7 RAW socket returned message flags When using recvmsg() call, the msg->msg_flags may contain following flags: diff --git a/include/uapi/linux/can/raw.h b/include/uapi/linux/can/raw.h index 78ec76fd89a6..8735f1080385 100644 --- a/include/uapi/linux/can/raw.h +++ b/include/uapi/linux/can/raw.h @@ -57,6 +57,7 @@ enum { CAN_RAW_LOOPBACK, /* local loopback (default:on) */ CAN_RAW_RECV_OWN_MSGS, /* receive my own msgs (default:off) */ CAN_RAW_FD_FRAMES, /* allow CAN FD frames (default:off) */ + CAN_RAW_JOIN_FILTERS, /* all filters must match to trigger */ }; #endif /* !_UAPI_CAN_RAW_H */ diff --git a/net/can/raw.c b/net/can/raw.c index 0c8d537b59b8..31b9748cbb4e 100644 --- a/net/can/raw.c +++ b/net/can/raw.c @@ -77,6 +77,7 @@ MODULE_ALIAS("can-proto-1"); struct uniqframe { ktime_t tstamp; const struct sk_buff *skb; + unsigned int join_rx_count; }; struct raw_sock { @@ -87,6 +88,7 @@ struct raw_sock { int loopback; int recv_own_msgs; int fd_frames; + int join_filters; int count; /* number of active filters */ struct can_filter dfilter; /* default/single filter */ struct can_filter *filter; /* pointer to filter(s) */ @@ -132,10 +134,21 @@ static void raw_rcv(struct sk_buff *oskb, void *data) /* eliminate multiple filter matches for the same skb */ if (this_cpu_ptr(ro->uniq)->skb == oskb && ktime_equal(this_cpu_ptr(ro->uniq)->tstamp, oskb->tstamp)) { - return; + if (ro->join_filters) { + this_cpu_inc(ro->uniq->join_rx_count); + /* drop frame until all enabled filters matched */ + if (this_cpu_ptr(ro->uniq)->join_rx_count < ro->count) + return; + } else { + return; + } } else { this_cpu_ptr(ro->uniq)->skb = oskb; this_cpu_ptr(ro->uniq)->tstamp = oskb->tstamp; + this_cpu_ptr(ro->uniq)->join_rx_count = 1; + /* drop first frame to check all enabled filters? */ + if (ro->join_filters && ro->count > 1) + return; } /* clone the given skb to be able to enqueue it into the rcv queue */ @@ -311,6 +324,7 @@ static int raw_init(struct sock *sk) ro->loopback = 1; ro->recv_own_msgs = 0; ro->fd_frames = 0; + ro->join_filters = 0; /* alloc_percpu provides zero'ed memory */ ro->uniq = alloc_percpu(struct uniqframe); @@ -604,6 +618,15 @@ static int raw_setsockopt(struct socket *sock, int level, int optname, break; + case CAN_RAW_JOIN_FILTERS: + if (optlen != sizeof(ro->join_filters)) + return -EINVAL; + + if (copy_from_user(&ro->join_filters, optval, optlen)) + return -EFAULT; + + break; + default: return -ENOPROTOOPT; } @@ -668,6 +691,12 @@ static int raw_getsockopt(struct socket *sock, int level, int optname, val = &ro->fd_frames; break; + case CAN_RAW_JOIN_FILTERS: + if (len > sizeof(int)) + len = sizeof(int); + val = &ro->join_filters; + break; + default: return -ENOPROTOOPT; } -- 2.20.1