can: gw: add a per rule limitation of frame hops
Usually the received CAN frames can be processed/routed as much as 'max_hops'
times (which is given at module load time of the can-gw module).
Introduce a new configuration option to reduce the number of possible hops
for a specific gateway rule to a value smaller then max_hops.
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
diff --git a/net/can/gw.c b/net/can/gw.c
index 2f291f9..3f9b0f3 100644
--- a/net/can/gw.c
+++ b/net/can/gw.c
@@ -146,6 +146,7 @@
/* tbc */
};
u8 gwtype;
+ u8 limit_hops;
u16 flags;
};
@@ -402,6 +403,11 @@
/* put the incremented hop counter in the cloned skb */
cgw_hops(nskb) = cgw_hops(skb) + 1;
+
+ /* first processing of this CAN frame -> adjust to private hop limit */
+ if (gwj->limit_hops && cgw_hops(nskb) == 1)
+ cgw_hops(nskb) = max_hops - gwj->limit_hops + 1;
+
nskb->dev = gwj->dst.dev;
/* pointer to modifiable CAN frame */
@@ -509,6 +515,11 @@
/* check non default settings of attributes */
+ if (gwj->limit_hops) {
+ if (nla_put_u8(skb, CGW_LIM_HOPS, gwj->limit_hops) < 0)
+ goto cancel;
+ }
+
if (gwj->mod.modtype.and) {
memcpy(&mb.cf, &gwj->mod.modframe.and, sizeof(mb.cf));
mb.modtype = gwj->mod.modtype.and;
@@ -606,11 +617,12 @@
[CGW_SRC_IF] = { .type = NLA_U32 },
[CGW_DST_IF] = { .type = NLA_U32 },
[CGW_FILTER] = { .len = sizeof(struct can_filter) },
+ [CGW_LIM_HOPS] = { .type = NLA_U8 },
};
/* check for common and gwtype specific attributes */
static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
- u8 gwtype, void *gwtypeattr)
+ u8 gwtype, void *gwtypeattr, u8 *limhops)
{
struct nlattr *tb[CGW_MAX+1];
struct cgw_frame_mod mb;
@@ -625,6 +637,13 @@
if (err < 0)
return err;
+ if (tb[CGW_LIM_HOPS]) {
+ *limhops = nla_get_u8(tb[CGW_LIM_HOPS]);
+
+ if (*limhops < 1 || *limhops > max_hops)
+ return -EINVAL;
+ }
+
/* check for AND/OR/XOR/SET modifications */
if (tb[CGW_MOD_AND]) {
@@ -782,6 +801,7 @@
{
struct rtcanmsg *r;
struct cgw_job *gwj;
+ u8 limhops = 0;
int err = 0;
if (!capable(CAP_NET_ADMIN))
@@ -808,7 +828,8 @@
gwj->flags = r->flags;
gwj->gwtype = r->gwtype;
- err = cgw_parse_attr(nlh, &gwj->mod, CGW_TYPE_CAN_CAN, &gwj->ccgw);
+ err = cgw_parse_attr(nlh, &gwj->mod, CGW_TYPE_CAN_CAN, &gwj->ccgw,
+ &limhops);
if (err < 0)
goto out;
@@ -836,6 +857,8 @@
if (gwj->dst.dev->type != ARPHRD_CAN || gwj->dst.dev->header_ops)
goto put_src_dst_out;
+ gwj->limit_hops = limhops;
+
ASSERT_RTNL();
err = cgw_register_filter(gwj);
@@ -867,13 +890,14 @@
}
}
-static int cgw_remove_job(struct sk_buff *skb, struct nlmsghdr *nlh)
+static int cgw_remove_job(struct sk_buff *skb, struct nlmsghdr *nlh)
{
struct cgw_job *gwj = NULL;
struct hlist_node *nx;
struct rtcanmsg *r;
struct cf_mod mod;
struct can_can_gw ccgw;
+ u8 limhops = 0;
int err = 0;
if (!capable(CAP_NET_ADMIN))
@@ -890,7 +914,7 @@
if (r->gwtype != CGW_TYPE_CAN_CAN)
return -EINVAL;
- err = cgw_parse_attr(nlh, &mod, CGW_TYPE_CAN_CAN, &ccgw);
+ err = cgw_parse_attr(nlh, &mod, CGW_TYPE_CAN_CAN, &ccgw, &limhops);
if (err < 0)
return err;
@@ -910,6 +934,9 @@
if (gwj->flags != r->flags)
continue;
+ if (gwj->limit_hops != limhops)
+ continue;
+
if (memcmp(&gwj->mod, &mod, sizeof(mod)))
continue;