[PATCH net-next 03/37] can: replace ARPHRD_CAN type checks with can_get_ml_priv()

[Marc Kleine-Budde <mkl@pengutronix.de>]

From: Oliver Hartkopp <socketcan@hartkopp.net>

Commit 4e096a18867a ("net: introduce CAN specific pointer in the struct
net_device") introduced an explicit way to assign the midlayer private
pointer (dev->ml_priv) to named users like ML_PRIV_CAN. A valid pointer
returned by can_get_ml_priv() therefore identifies a real CAN device.

The referenced commit only converted the j1939 and proc code to this
check, while the other parts of the CAN subsystem still rely on
dev->type == ARPHRD_CAN.

The TUNSETLINK ioctl allows a down TUN/TAP device to set its hardware
type to ARPHRD_CAN while dev->ml_priv remains NULL. Such a repurposed
netdevice passes the ARPHRD_CAN checks and triggers a NULL pointer
dereference when CAN filters are created and when they are removed,
e.g. by the CAN protocols' netdevice notifier handlers. This only
requires owning a TUN/TAP device or CAP_NET_ADMIN in an unprivileged
user namespace.

Convert the remaining ARPHRD_CAN checks in af_can, bcm, gw, isotp and
raw to can_get_ml_priv().

Fixes: 4e096a18867a ("net: introduce CAN specific pointer in the struct net_device")
Cc: stable@kernel.org
Cc: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://patch.msgid.link/20261012164802.94113-1-socketcan@hartkopp.net
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 net/can/af_can.c | 15 ++++++---------
 net/can/bcm.c    |  7 ++++---
 net/can/gw.c     |  7 ++++---
 net/can/isotp.c  |  5 +++--
 net/can/raw.c    |  4 ++--
 5 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/net/can/af_can.c b/net/can/af_can.c
index 34fe3b28d576..dc27ace43719 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -226,7 +226,7 @@ int can_send(struct sk_buff *skb, int loop)
 		goto inval_skb;
 	}
 
-	if (unlikely(skb->dev->type != ARPHRD_CAN)) {
+	if (unlikely(!can_get_ml_priv(skb->dev))) {
 		err = -EPERM;
 		goto inval_skb;
 	}
@@ -452,7 +452,7 @@ int can_rx_register(struct net *net, struct net_device *dev, canid_t can_id,
 
 	/* insert new receiver  (dev,canid,mask) -> (func,data) */
 
-	if (dev && (dev->type != ARPHRD_CAN || !can_get_ml_priv(dev)))
+	if (dev && !can_get_ml_priv(dev))
 		return -ENODEV;
 
 	if (dev && !net_eq(net, dev_net(dev)))
@@ -519,7 +519,7 @@ void can_rx_unregister(struct net *net, struct net_device *dev, canid_t can_id,
 	struct can_rcv_lists_stats *rcv_lists_stats = net->can.rcv_lists_stats;
 	struct can_dev_rcv_lists *dev_rcv_lists;
 
-	if (dev && dev->type != ARPHRD_CAN)
+	if (dev && !can_get_ml_priv(dev))
 		return;
 
 	if (dev && !net_eq(net, dev_net(dev)))
@@ -684,8 +684,7 @@ static int can_rcv(struct sk_buff *skb, struct net_device *dev,
 {
 	struct can_skb_ext *csx = can_skb_ext_find(skb);
 
-	if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) ||
-		     !csx || !can_is_can_skb(skb))) {
+	if (unlikely(!can_get_ml_priv(dev) || !csx || !can_is_can_skb(skb))) {
 		pr_warn_once("PF_CAN: dropped non conform CAN skbuff: dev type %d, len %d\n",
 			     dev->type, skb->len);
 
@@ -710,8 +709,7 @@ static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
 {
 	struct can_skb_ext *csx = can_skb_ext_find(skb);
 
-	if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) ||
-		     !csx || !can_is_canfd_skb(skb))) {
+	if (unlikely(!can_get_ml_priv(dev) || !csx || !can_is_canfd_skb(skb))) {
 		pr_warn_once("PF_CAN: dropped non conform CAN FD skbuff: dev type %d, len %d\n",
 			     dev->type, skb->len);
 
@@ -736,8 +734,7 @@ static int canxl_rcv(struct sk_buff *skb, struct net_device *dev,
 {
 	struct can_skb_ext *csx = can_skb_ext_find(skb);
 
-	if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) ||
-		     !csx || !can_is_canxl_skb(skb))) {
+	if (unlikely(!can_get_ml_priv(dev) || !csx || !can_is_canxl_skb(skb))) {
 		pr_warn_once("PF_CAN: dropped non conform CAN XL skbuff: dev type %d, len %d\n",
 			     dev->type, skb->len);
 
diff --git a/net/can/bcm.c b/net/can/bcm.c
index 3d637a1e0ac1..60406439a13f 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -54,6 +54,7 @@
 #include <linux/if_arp.h>
 #include <linux/skbuff.h>
 #include <linux/can.h>
+#include <linux/can/can-ml.h>
 #include <linux/can/core.h>
 #include <linux/can/skb.h>
 #include <linux/can/bcm.h>
@@ -1719,7 +1720,7 @@ static int bcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 				goto out_release;
 			}
 
-			if (dev->type != ARPHRD_CAN) {
+			if (!can_get_ml_priv(dev)) {
 				dev_put(dev);
 				ret = -ENODEV;
 				goto out_release;
@@ -1867,7 +1868,7 @@ static int bcm_notifier(struct notifier_block *nb, unsigned long msg,
 {
 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 
-	if (dev->type != ARPHRD_CAN)
+	if (!can_get_ml_priv(dev))
 		return NOTIFY_DONE;
 	if (msg != NETDEV_UNREGISTER && msg != NETDEV_DOWN)
 		return NOTIFY_DONE;
@@ -2024,7 +2025,7 @@ static int bcm_connect(struct socket *sock, struct sockaddr_unsized *uaddr, int
 			ret = -ENODEV;
 			goto fail;
 		}
-		if (dev->type != ARPHRD_CAN) {
+		if (!can_get_ml_priv(dev)) {
 			dev_put(dev);
 			ret = -ENODEV;
 			goto fail;
diff --git a/net/can/gw.c b/net/can/gw.c
index 5793cb2420ed..54bb5bd3242a 100644
--- a/net/can/gw.c
+++ b/net/can/gw.c
@@ -52,6 +52,7 @@
 #include <linux/if_arp.h>
 #include <linux/skbuff.h>
 #include <linux/can.h>
+#include <linux/can/can-ml.h>
 #include <linux/can/core.h>
 #include <linux/can/skb.h>
 #include <linux/can/gw.h>
@@ -612,7 +613,7 @@ static int cgw_notifier(struct notifier_block *nb,
 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 	struct net *net = dev_net(dev);
 
-	if (dev->type != ARPHRD_CAN)
+	if (!can_get_ml_priv(dev))
 		return NOTIFY_DONE;
 
 	if (msg == NETDEV_UNREGISTER) {
@@ -1163,7 +1164,7 @@ static int cgw_create_job(struct sk_buff *skb,  struct nlmsghdr *nlh,
 	if (!gwj->src.dev)
 		goto out;
 
-	if (gwj->src.dev->type != ARPHRD_CAN)
+	if (!can_get_ml_priv(gwj->src.dev))
 		goto out;
 
 	gwj->dst.dev = __dev_get_by_index(net, gwj->ccgw.dst_idx);
@@ -1171,7 +1172,7 @@ static int cgw_create_job(struct sk_buff *skb,  struct nlmsghdr *nlh,
 	if (!gwj->dst.dev)
 		goto out;
 
-	if (gwj->dst.dev->type != ARPHRD_CAN)
+	if (!can_get_ml_priv(gwj->dst.dev))
 		goto out;
 
 	/* is sending the skb back to the incoming interface intended? */
diff --git a/net/can/isotp.c b/net/can/isotp.c
index f5dc9d04bd68..6c28802c0605 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -65,6 +65,7 @@
 #include <linux/if_arp.h>
 #include <linux/skbuff.h>
 #include <linux/can.h>
+#include <linux/can/can-ml.h>
 #include <linux/can/core.h>
 #include <linux/can/skb.h>
 #include <linux/can/isotp.h>
@@ -1610,7 +1611,7 @@ static int isotp_bind(struct socket *sock, struct sockaddr_unsized *uaddr, int l
 		err = -ENODEV;
 		goto out;
 	}
-	if (dev->type != ARPHRD_CAN) {
+	if (!can_get_ml_priv(dev)) {
 		err = -ENODEV;
 		goto out_put_dev;
 	}
@@ -1897,7 +1898,7 @@ static int isotp_notifier(struct notifier_block *nb, unsigned long msg,
 {
 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 
-	if (dev->type != ARPHRD_CAN)
+	if (!can_get_ml_priv(dev))
 		return NOTIFY_DONE;
 	if (msg != NETDEV_UNREGISTER && msg != NETDEV_DOWN)
 		return NOTIFY_DONE;
diff --git a/net/can/raw.c b/net/can/raw.c
index 6944ebab3feb..ad611906b308 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -348,7 +348,7 @@ static int raw_notifier(struct notifier_block *nb, unsigned long msg,
 {
 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 
-	if (dev->type != ARPHRD_CAN)
+	if (!can_get_ml_priv(dev))
 		return NOTIFY_DONE;
 	if (msg != NETDEV_UNREGISTER && msg != NETDEV_DOWN)
 		return NOTIFY_DONE;
@@ -491,7 +491,7 @@ static int raw_bind(struct socket *sock, struct sockaddr_unsized *uaddr, int len
 			err = -ENODEV;
 			goto out;
 		}
-		if (dev->type != ARPHRD_CAN) {
+		if (!can_get_ml_priv(dev)) {
 			err = -ENODEV;
 			goto out_put_dev;
 		}
-- 
2.53.0