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Diffstat (limited to 'net/can/gw.c')
-rw-r--r--net/can/gw.c72
1 files changed, 56 insertions, 16 deletions
diff --git a/net/can/gw.c b/net/can/gw.c
index 574dda78eb0f..c185fcd5e828 100644
--- a/net/can/gw.c
+++ b/net/can/gw.c
@@ -42,6 +42,7 @@
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
+#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/rcupdate.h>
@@ -52,19 +53,31 @@
#include <linux/skbuff.h>
#include <linux/can.h>
#include <linux/can/core.h>
+#include <linux/can/skb.h>
#include <linux/can/gw.h>
#include <net/rtnetlink.h>
#include <net/net_namespace.h>
#include <net/sock.h>
-#define CAN_GW_VERSION "20101209"
-static __initconst const char banner[] =
- KERN_INFO "can: netlink gateway (rev " CAN_GW_VERSION ")\n";
+#define CAN_GW_VERSION "20130117"
+#define CAN_GW_NAME "can-gw"
MODULE_DESCRIPTION("PF_CAN netlink gateway");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Oliver Hartkopp <oliver.hartkopp@volkswagen.de>");
-MODULE_ALIAS("can-gw");
+MODULE_ALIAS(CAN_GW_NAME);
+
+#define CGW_MIN_HOPS 1
+#define CGW_MAX_HOPS 6
+#define CGW_DEFAULT_HOPS 1
+
+static unsigned int max_hops __read_mostly = CGW_DEFAULT_HOPS;
+module_param(max_hops, uint, S_IRUGO);
+MODULE_PARM_DESC(max_hops,
+ "maximum " CAN_GW_NAME " routing hops for CAN frames "
+ "(valid values: " __stringify(CGW_MIN_HOPS) "-"
+ __stringify(CGW_MAX_HOPS) " hops, "
+ "default: " __stringify(CGW_DEFAULT_HOPS) ")");
static HLIST_HEAD(cgw_list);
static struct notifier_block notifier;
@@ -118,6 +131,7 @@ struct cgw_job {
struct rcu_head rcu;
u32 handled_frames;
u32 dropped_frames;
+ u32 deleted_frames;
struct cf_mod mod;
union {
/* CAN frame data source */
@@ -338,15 +352,38 @@ static void can_can_gw_rcv(struct sk_buff *skb, void *data)
struct sk_buff *nskb;
int modidx = 0;
- /* do not handle already routed frames - see comment below */
- if (skb_mac_header_was_set(skb))
+ /*
+ * Do not handle CAN frames routed more than 'max_hops' times.
+ * In general we should never catch this delimiter which is intended
+ * to cover a misconfiguration protection (e.g. circular CAN routes).
+ *
+ * The Controller Area Network controllers only accept CAN frames with
+ * correct CRCs - which are not visible in the controller registers.
+ * According to skbuff.h documentation the csum_start element for IP
+ * checksums is undefined/unsued when ip_summed == CHECKSUM_UNNECESSARY.
+ * Only CAN skbs can be processed here which already have this property.
+ */
+
+#define cgw_hops(skb) ((skb)->csum_start)
+
+ BUG_ON(skb->ip_summed != CHECKSUM_UNNECESSARY);
+
+ if (cgw_hops(skb) >= max_hops) {
+ /* indicate deleted frames due to misconfiguration */
+ gwj->deleted_frames++;
return;
+ }
if (!(gwj->dst.dev->flags & IFF_UP)) {
gwj->dropped_frames++;
return;
}
+ /* is sending the skb back to the incoming interface not allowed? */
+ if (!(gwj->flags & CGW_FLAGS_CAN_IIF_TX_OK) &&
+ can_skb_prv(skb)->ifindex == gwj->dst.dev->ifindex)
+ return;
+
/*
* clone the given skb, which has not been done in can_rcv()
*
@@ -363,15 +400,8 @@ static void can_can_gw_rcv(struct sk_buff *skb, void *data)
return;
}
- /*
- * Mark routed frames by setting some mac header length which is
- * not relevant for the CAN frames located in the skb->data section.
- *
- * As dev->header_ops is not set in CAN netdevices no one is ever
- * accessing the various header offsets in the CAN skbuffs anyway.
- * E.g. using the packet socket to read CAN frames is still working.
- */
- skb_set_mac_header(nskb, 8);
+ /* put the incremented hop counter in the cloned skb */
+ cgw_hops(nskb) = cgw_hops(skb) + 1;
nskb->dev = gwj->dst.dev;
/* pointer to modifiable CAN frame */
@@ -472,6 +502,11 @@ static int cgw_put_job(struct sk_buff *skb, struct cgw_job *gwj, int type,
goto cancel;
}
+ if (gwj->deleted_frames) {
+ if (nla_put_u32(skb, CGW_DELETED, gwj->deleted_frames) < 0)
+ goto cancel;
+ }
+
/* check non default settings of attributes */
if (gwj->mod.modtype.and) {
@@ -771,6 +806,7 @@ static int cgw_create_job(struct sk_buff *skb, struct nlmsghdr *nlh,
gwj->handled_frames = 0;
gwj->dropped_frames = 0;
+ gwj->deleted_frames = 0;
gwj->flags = r->flags;
gwj->gwtype = r->gwtype;
@@ -895,7 +931,11 @@ static int cgw_remove_job(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
static __init int cgw_module_init(void)
{
- printk(banner);
+ /* sanitize given module parameter */
+ max_hops = clamp_t(unsigned int, max_hops, CGW_MIN_HOPS, CGW_MAX_HOPS);
+
+ pr_info("can: netlink gateway (rev " CAN_GW_VERSION ") max_hops=%d\n",
+ max_hops);
cgw_cache = kmem_cache_create("can_gw", sizeof(struct cgw_job),
0, 0, NULL);