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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>
This commit is contained in:
Oliver Hartkopp 2013-08-26 15:05:36 +02:00 committed by Marc Kleine-Budde
parent 1149108e2f
commit 391ac1282d
2 changed files with 39 additions and 5 deletions
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9
include/uapi/linux/can/gw.h
View File

@ -45,6 +45,7 @@ enum {
CGW_DST_IF, /* ifindex of destination network interface */
CGW_FILTER, /* specify struct can_filter on source CAN device */
CGW_DELETED, /* number of deleted CAN frames (see max_hops param) */
CGW_LIM_HOPS, /* limit the number of hops of this specific rule */
__CGW_MAX
};
@ -116,13 +117,19 @@ enum {
* Sets a CAN receive filter for the gateway job specified by the
* struct can_filter described in include/linux/can.h
*
* CGW_MOD_XXX (length 17 bytes):
* CGW_MOD_(AND|OR|XOR|SET) (length 17 bytes):
* Specifies a modification that's done to a received CAN frame before it is
* send out to the destination interface.
*
* <struct can_frame> data used as operator
* <u8> affected CAN frame elements
*
* CGW_LIM_HOPS (length 1 byte):
* Limit the number of hops of this specific rule. Usually the received CAN
* frame can be processed as much as 'max_hops' times (which is given at module
* load time of the can-gw module). This value is used to reduce the number of
* possible hops for this gateway rule to a value smaller then max_hops.
*
* CGW_CS_XOR (length 4 bytes):
* Set a simple XOR checksum starting with an initial value into
* data[result-idx] using data[start-idx] .. data[end-idx]

35
net/can/gw.c
View File

@ -146,6 +146,7 @@ struct cgw_job {
/* tbc */
};
u8 gwtype;
u8 limit_hops;
u16 flags;
};
@ -402,6 +403,11 @@ static void can_can_gw_rcv(struct sk_buff *skb, void *data)
/* 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 @@ static int cgw_put_job(struct sk_buff *skb, struct cgw_job *gwj, int type,
/* 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 @@ static const struct nla_policy cgw_policy[CGW_MAX+1] = {
[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 @@ static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
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 @@ static int cgw_create_job(struct sk_buff *skb, struct nlmsghdr *nlh)
{
struct rtcanmsg *r;
struct cgw_job *gwj;
u8 limhops = 0;
int err = 0;
if (!capable(CAP_NET_ADMIN))
@ -808,7 +828,8 @@ static int cgw_create_job(struct sk_buff *skb, struct nlmsghdr *nlh)
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 @@ static int cgw_create_job(struct sk_buff *skb, struct nlmsghdr *nlh)
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 void cgw_remove_all_jobs(void)
}
}
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 @@ static int cgw_remove_job(struct sk_buff *skb, struct nlmsghdr *nlh)
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 @@ static int cgw_remove_job(struct sk_buff *skb, struct nlmsghdr *nlh)
if (gwj->flags != r->flags)
continue;
if (gwj->limit_hops != limhops)
continue;
if (memcmp(&gwj->mod, &mod, sizeof(mod)))
continue;