2 files changed, 61 insertions, 12 deletions

diff --git a/include/uapi/linux/can/gw.h b/include/uapi/linux/can/gw.h
index 3e6184cf2f6d..5079b9d57e31 100644
--- a/include/uapi/linux/can/gw.h
+++ b/include/uapi/linux/can/gw.h
@@ -78,6 +78,7 @@ enum {
 	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_MOD_UID,	/* user defined identifier for modification updates */
 	__CGW_MAX
 };
 
@@ -162,6 +163,10 @@ enum {
  * 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_MOD_UID (length 4 bytes):
+ * Optional non-zero user defined routing job identifier to alter existing
+ * modification settings at runtime.
+ *
  * 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]
diff --git a/net/can/gw.c b/net/can/gw.c
index a6f448e18ea8..455168718c2e 100644
--- a/net/can/gw.c
+++ b/net/can/gw.c
@@ -110,6 +110,7 @@ struct cf_mod {
 		void (*xor)(struct can_frame *cf, struct cgw_csum_xor *xor);
 		void (*crc8)(struct can_frame *cf, struct cgw_csum_crc8 *crc8);
 	} csumfunc;
+	u32 uid;
 };
 
 
@@ -548,6 +549,11 @@ static int cgw_put_job(struct sk_buff *skb, struct cgw_job *gwj, int type,
 			goto cancel;
 	}
 
+	if (gwj->mod.uid) {
+		if (nla_put_u32(skb, CGW_MOD_UID, gwj->mod.uid) < 0)
+			goto cancel;
+	}
+
 	if (gwj->mod.csumfunc.crc8) {
 		if (nla_put(skb, CGW_CS_CRC8, CGW_CS_CRC8_LEN,
 			    &gwj->mod.csum.crc8) < 0)
@@ -619,6 +625,7 @@ static const struct nla_policy cgw_policy[CGW_MAX+1] = {
 	[CGW_DST_IF]	= { .type = NLA_U32 },
 	[CGW_FILTER]	= { .len = sizeof(struct can_filter) },
 	[CGW_LIM_HOPS]	= { .type = NLA_U8 },
+	[CGW_MOD_UID]	= { .type = NLA_U32 },
 };
 
 /* check for common and gwtype specific attributes */
@@ -761,6 +768,10 @@ static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
 			else
 				mod->csumfunc.xor = cgw_csum_xor_neg;
 		}
+
+		if (tb[CGW_MOD_UID]) {
+			nla_memcpy(&mod->uid, tb[CGW_MOD_UID], sizeof(u32));
+		}
 	}
 
 	if (gwtype == CGW_TYPE_CAN_CAN) {
@@ -802,6 +813,8 @@ static int cgw_create_job(struct sk_buff *skb,  struct nlmsghdr *nlh)
 {
 	struct rtcanmsg *r;
 	struct cgw_job *gwj;
+	struct cf_mod mod;
+	struct can_can_gw ccgw;
 	u8 limhops = 0;
 	int err = 0;
 
@@ -819,6 +832,36 @@ static int cgw_create_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, &limhops);
+	if (err < 0)
+		return err;
+
+	if (mod.uid) {
+
+		ASSERT_RTNL();
+
+		/* check for updating an existing job with identical uid */
+		hlist_for_each_entry(gwj, &cgw_list, list) {
+
+			if (gwj->mod.uid != mod.uid)
+				continue;
+
+			/* interfaces & filters must be identical */
+			if (memcmp(&gwj->ccgw, &ccgw, sizeof(ccgw)))
+				return -EINVAL;
+
+			/* update modifications with disabled softirq & quit */
+			local_bh_disable();
+			memcpy(&gwj->mod, &mod, sizeof(mod));
+			local_bh_enable();
+			return 0;
+		}
+	}
+
+	/* ifindex == 0 is not allowed for job creation */
+	if (!ccgw.src_idx || !ccgw.dst_idx)
+		return -ENODEV;
+
 	gwj = kmem_cache_alloc(cgw_cache, GFP_KERNEL);
 	if (!gwj)
 		return -ENOMEM;
@@ -828,18 +871,14 @@ static int cgw_create_job(struct sk_buff *skb,  struct nlmsghdr *nlh)
 	gwj->deleted_frames = 0;
 	gwj->flags = r->flags;
 	gwj->gwtype = r->gwtype;
+	gwj->limit_hops = limhops;
 
-	err = cgw_parse_attr(nlh, &gwj->mod, CGW_TYPE_CAN_CAN, &gwj->ccgw,
-			     &limhops);
-	if (err < 0)
-		goto out;
+	/* insert already parsed information */
+	memcpy(&gwj->mod, &mod, sizeof(mod));
+	memcpy(&gwj->ccgw, &ccgw, sizeof(ccgw));
 
 	err = -ENODEV;
 
-	/* ifindex == 0 is not allowed for job creation */
-	if (!gwj->ccgw.src_idx || !gwj->ccgw.dst_idx)
-		goto out;
-
 	gwj->src.dev = __dev_get_by_index(&init_net, gwj->ccgw.src_idx);
 
 	if (!gwj->src.dev)
@@ -856,8 +895,6 @@ static int cgw_create_job(struct sk_buff *skb,  struct nlmsghdr *nlh)
 	if (gwj->dst.dev->type != ARPHRD_CAN)
 		goto out;
 
-	gwj->limit_hops = limhops;
-
 	ASSERT_RTNL();
 
 	err = cgw_register_filter(gwj);
@@ -931,8 +968,15 @@ static int cgw_remove_job(struct sk_buff *skb, struct nlmsghdr *nlh)
 		if (gwj->limit_hops != limhops)
 			continue;
 
-		if (memcmp(&gwj->mod, &mod, sizeof(mod)))
-			continue;
+		/* we have a match when uid is enabled and identical */
+		if (gwj->mod.uid || mod.uid) {
+			if (gwj->mod.uid != mod.uid)
+				continue;
+		} else {
+			/* no uid => check for identical modifications */
+			if (memcmp(&gwj->mod, &mod, sizeof(mod)))
+				continue;
+		}
 
 		/* if (r->gwtype == CGW_TYPE_CAN_CAN) - is made sure here */
 		if (memcmp(&gwj->ccgw, &ccgw, sizeof(ccgw)))