* [PATCH v3 1/3] can: remove CAN filters independent from namespace
2026-09-28 19:24 [PATCH v3 0/3] CAN netlayer fixes for stable Oliver Hartkopp
@ 2026-09-28 19:24 ` Oliver Hartkopp
2026-09-28 19:24 ` [PATCH v3 2/3] can: convert unreliable ARPHRD_CAN type checks to robust can_get_ml_priv() Oliver Hartkopp
2026-09-28 19:24 ` [PATCH v3 3/3] can: fix unique skb identifier regression under RPS Oliver Hartkopp
2 siblings, 0 replies; 4+ messages in thread
From: Oliver Hartkopp @ 2026-09-28 19:24 UTC (permalink / raw)
To: linux-can; +Cc: Oliver Hartkopp, Norbert Szetei, stable
When the devices namespace is changed the socket namespace and the device
namespace might differ. The net_eq(dev_net(dev), sock_net(sk)) check in
the CAN protocols netdev notifiers therefore led to skipping the required
removal of the CAN filters from the (namespace changed) CAN devices.
This patch removes the namespace equality check in the netdev notifiers for
BCM, ISOTP and RAW sockets. Since the struct net_device pointer is globally
unique, the notifier should always process the unregister event and remove
the CAN filters if it matches the original socket's bound device pointer.
In bcm.c netdevice comparisons were performed by checking the interface
index (bo->ifindex and op->ifindex) which is not namespace-safe either.
Introduce tracked netdevice pointers (bo->dev and op->tx_dev) for these
referenced devices to enable namespace-save device comparisons.
Additional put all bo->dev accesses in bcm_notify() under lock_sock().
In isotp.c the two missing can_rx_unregister() calling sites are converted
to use dev_net(dev) instead of sock_net(sk) to get the correct namespace.
Fixes: 8e8cda6d737d ("can: initial support for network namespaces")
Reported-by: Norbert Szetei <norbert@doyensec.com>
Link: https://lore.kernel.org/linux-can/CEA6A38A-2646-4ADA-95B4-CBAE2F301A8E@doyensec.com/
Cc: stable@vger.kernel.org
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
---
net/can/bcm.c | 100 ++++++++++++++++++++++++++++++++++++------------
net/can/isotp.c | 7 +---
net/can/raw.c | 3 --
3 files changed, 78 insertions(+), 32 deletions(-)
diff --git a/net/can/bcm.c b/net/can/bcm.c
index 3d637a1e0ac1..cd3522ec32c0 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -128,18 +128,22 @@ struct bcm_op {
struct canfd_frame sframe;
struct canfd_frame last_sframe;
struct sock *sk;
struct net_device *rx_reg_dev;
netdevice_tracker rx_reg_dev_tracker;
+ struct net_device *tx_dev;
+ netdevice_tracker tx_dev_tracker;
spinlock_t bcm_tx_lock; /* protect tx data and timer updates */
spinlock_t bcm_rx_update_lock; /* protect filter/timer data updates */
};
struct bcm_sock {
struct sock sk;
int bound;
int ifindex;
+ struct net_device *dev;
+ netdevice_tracker dev_tracker;
struct list_head notifier;
struct list_head rx_ops;
struct list_head tx_ops;
unsigned long dropped_usr_msgs;
struct proc_dir_entry *bcm_proc_read;
@@ -933,10 +937,13 @@ static void bcm_free_op_work(struct work_struct *work)
kfree(op->frames);
if ((op->last_frames) && (op->last_frames != &op->last_sframe))
kfree(op->last_frames);
+ if (op->tx_dev)
+ netdev_put(op->tx_dev, &op->tx_dev_tracker);
+
/* the last possible access to op->timer/op->thrtimer has now
* happened above via hrtimer_cancel() - op->sk is no longer
* needed by any pending timer callback, so drop our reference
*/
sock_put(op->sk);
@@ -1072,10 +1079,11 @@ static int bcm_tx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
int ifindex, struct sock *sk)
{
struct bcm_sock *bo = bcm_sk(sk);
struct bcm_op *op;
struct canfd_frame *cf;
+ struct net_device *tx_dev;
bool add_op_to_list = false;
unsigned int i;
int err;
/* we need a real device to send frames */
@@ -1103,10 +1111,26 @@ static int bcm_tx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
* therefore (complexity / locking) it is not supported.
*/
if (msg_head->nframes > op->nframes)
return -E2BIG;
+ /* Re-resolve and re-hold the target device if a concurrent
+ * NETDEV_UNREGISTER already cleared it (see bcm_notify()).
+ * op->ifindex and sock_net(sk) is unchanged.
+ */
+ if (!op->tx_dev) {
+ tx_dev = dev_get_by_index(sock_net(sk), ifindex);
+ if (tx_dev) {
+ op->tx_dev = tx_dev;
+ netdev_hold(tx_dev, &op->tx_dev_tracker,
+ GFP_KERNEL);
+ dev_put(tx_dev);
+ } else {
+ return -ENODEV;
+ }
+ }
+
/* get new CAN frames content into a staging buffer before
* locking: validate and normalize the frames there so that
* bcm_can_tx() / bcm_tx_timeout_handler() never observe a
* partially updated or unvalidated frame in op->frames
*/
@@ -1169,10 +1193,22 @@ static int bcm_tx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
op = kzalloc(OPSIZ, GFP_KERNEL);
if (!op)
return -ENOMEM;
+ tx_dev = dev_get_by_index(sock_net(sk), ifindex);
+ if (tx_dev) {
+ op->tx_dev = tx_dev;
+ netdev_hold(tx_dev, &op->tx_dev_tracker, GFP_KERNEL);
+ dev_put(tx_dev);
+ } else {
+ /* prepare op->frames for goto free_op */
+ op->frames = &op->sframe;
+ err = -ENODEV;
+ goto free_op;
+ }
+
spin_lock_init(&op->bcm_tx_lock);
op->can_id = msg_head->can_id;
op->cfsiz = CFSIZ(msg_head->flags);
op->flags = msg_head->flags;
op->nframes = msg_head->nframes;
@@ -1184,12 +1220,14 @@ static int bcm_tx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
if (msg_head->nframes > 1) {
op->frames = kmalloc_array(msg_head->nframes,
op->cfsiz,
GFP_KERNEL);
if (!op->frames) {
- kfree(op);
- return -ENOMEM;
+ /* prepare op->frames for goto free_op */
+ op->frames = &op->sframe;
+ err = -ENOMEM;
+ goto free_op;
}
} else
op->frames = &op->sframe;
for (i = 0; i < msg_head->nframes; i++) {
@@ -1267,10 +1305,13 @@ static int bcm_tx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
bcm_tx_start_timer(op);
return msg_head->nframes * op->cfsiz + MHSIZ;
free_op:
+ if (op->tx_dev)
+ netdev_put(op->tx_dev, &op->tx_dev_tracker);
+
if (op->frames != &op->sframe)
kfree(op->frames);
kfree(op);
return err;
}
@@ -1790,46 +1831,47 @@ static int bcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
static void bcm_notify(struct bcm_sock *bo, unsigned long msg,
struct net_device *dev)
{
struct sock *sk = &bo->sk;
struct bcm_op *op;
- int notify_enodev = 0;
+ int sk_err = 0;
- if (!net_eq(dev_net(dev), sock_net(sk)))
- return;
+ lock_sock(sk);
switch (msg) {
case NETDEV_UNREGISTER:
- lock_sock(sk);
/* rx_ops: remove device specific receive entries */
list_for_each_entry(op, &bo->rx_ops, list) {
if (op->rx_reg_dev == dev)
bcm_rx_unreg(dev, op);
/* release an ANYDEV op's claim (see bcm_rx_handler())
* on this now confirmed-gone interface.
*/
- if (!op->ifindex) {
+ if (!op->ifindex && net_eq(dev_net(dev), sock_net(sk))) {
spin_lock_bh(&op->bcm_rx_update_lock);
if (op->if_detected == dev->ifindex)
op->if_detected = 0;
spin_unlock_bh(&op->bcm_rx_update_lock);
}
}
/* tx_ops: stop device specific cyclic transmissions on the
- * vanishing ifindex. Cancelling the timer is enough to stop
+ * vanishing device. Cancelling the timer is enough to stop
* cyclic bcm_can_tx() calls as there is no re-arming.
*/
list_for_each_entry(op, &bo->tx_ops, list)
- if (op->ifindex == dev->ifindex)
+ if (op->tx_dev == dev) {
hrtimer_cancel(&op->timer);
+ netdev_put(op->tx_dev, &op->tx_dev_tracker);
+ op->tx_dev = NULL;
+ }
/* remove device reference, if this is our bound device */
- if (bo->bound && bo->ifindex == dev->ifindex) {
+ if (bo->bound && bo->dev == dev) {
#if IS_ENABLED(CONFIG_PROC_FS)
if (sock_net(sk)->can.bcmproc_dir && bo->bcm_proc_read) {
remove_proc_entry(bo->procname, sock_net(sk)->can.bcmproc_dir);
bo->bcm_proc_read = NULL;
}
@@ -1839,28 +1881,27 @@ static void bcm_notify(struct bcm_sock *bo, unsigned long msg,
* accessed under lock_sock() so it needs no
* annotation.
*/
WRITE_ONCE(bo->bound, 0);
bo->ifindex = 0;
- notify_enodev = 1;
- }
-
- release_sock(sk);
-
- if (notify_enodev) {
- sk->sk_err = ENODEV;
- if (!sock_flag(sk, SOCK_DEAD))
- sk_error_report(sk);
+ netdev_put(bo->dev, &bo->dev_tracker);
+ bo->dev = NULL;
+ sk_err = ENODEV;
}
break;
case NETDEV_DOWN:
- if (bo->bound && bo->ifindex == dev->ifindex) {
- sk->sk_err = ENETDOWN;
- if (!sock_flag(sk, SOCK_DEAD))
- sk_error_report(sk);
- }
+ if (bo->bound && bo->dev == dev)
+ sk_err = ENETDOWN;
+ }
+
+ release_sock(sk);
+
+ if (sk_err) {
+ sk->sk_err = sk_err;
+ if (!sock_flag(sk, SOCK_DEAD))
+ sk_error_report(sk);
}
}
static int bcm_notifier(struct notifier_block *nb, unsigned long msg,
void *ptr)
@@ -1982,10 +2023,14 @@ static int bcm_release(struct socket *sock)
/* remove device reference */
if (bo->bound) {
WRITE_ONCE(bo->bound, 0);
bo->ifindex = 0;
+ if (bo->dev) {
+ netdev_put(bo->dev, &bo->dev_tracker);
+ bo->dev = NULL;
+ }
}
sock_orphan(sk);
sock->sk = NULL;
@@ -2029,25 +2074,32 @@ static int bcm_connect(struct socket *sock, struct sockaddr_unsized *uaddr, int
ret = -ENODEV;
goto fail;
}
bo->ifindex = dev->ifindex;
+ bo->dev = dev;
+ netdev_hold(dev, &bo->dev_tracker, GFP_KERNEL);
dev_put(dev);
} else {
/* no interface reference for ifindex = 0 ('any' CAN device) */
bo->ifindex = 0;
+ bo->dev = NULL;
}
#if IS_ENABLED(CONFIG_PROC_FS)
if (net->can.bcmproc_dir) {
/* unique socket address as filename */
sprintf(bo->procname, "%llu", sock_i_ino(sk));
bo->bcm_proc_read = proc_create_net_single(bo->procname, 0644,
net->can.bcmproc_dir,
bcm_proc_show, sk);
if (!bo->bcm_proc_read) {
+ if (bo->dev) {
+ netdev_put(bo->dev, &bo->dev_tracker);
+ bo->dev = NULL;
+ }
ret = -ENOMEM;
goto fail;
}
}
#endif /* CONFIG_PROC_FS */
diff --git a/net/can/isotp.c b/net/can/isotp.c
index 155530aedce2..0835a4758a72 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -1490,15 +1490,15 @@ static int isotp_release(struct socket *sock)
/* remove current filters & unregister
* tracked reference so->dev is taken at bind() time with rtnl_lock
*/
if (so->bound && so->dev) {
if (isotp_register_rxid(so))
- can_rx_unregister(net, so->dev, so->rxid,
+ can_rx_unregister(dev_net(so->dev), so->dev, so->rxid,
SINGLE_MASK(so->rxid),
isotp_rcv, sk);
- can_rx_unregister(net, so->dev, so->txid,
+ can_rx_unregister(dev_net(so->dev), so->dev, so->txid,
SINGLE_MASK(so->txid),
isotp_rcv_echo, sk);
netdev_put(so->dev, &so->dev_tracker);
}
@@ -1846,13 +1846,10 @@ static int isotp_getsockopt(struct socket *sock, int level, int optname,
static void isotp_notify(struct isotp_sock *so, unsigned long msg,
struct net_device *dev)
{
struct sock *sk = &so->sk;
- if (!net_eq(dev_net(dev), sock_net(sk)))
- return;
-
if (so->dev != dev)
return;
switch (msg) {
case NETDEV_UNREGISTER:
diff --git a/net/can/raw.c b/net/can/raw.c
index 82d9c0499c95..c5596fc9aac5 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -300,13 +300,10 @@ static int raw_enable_allfilters(struct net *net, struct net_device *dev,
static void raw_notify(struct raw_sock *ro, unsigned long msg,
struct net_device *dev)
{
struct sock *sk = &ro->sk;
- if (!net_eq(dev_net(dev), sock_net(sk)))
- return;
-
if (ro->dev != dev)
return;
switch (msg) {
case NETDEV_UNREGISTER:
--
2.53.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH v3 2/3] can: convert unreliable ARPHRD_CAN type checks to robust can_get_ml_priv()
2026-09-28 19:24 [PATCH v3 0/3] CAN netlayer fixes for stable Oliver Hartkopp
2026-09-28 19:24 ` [PATCH v3 1/3] can: remove CAN filters independent from namespace Oliver Hartkopp
@ 2026-09-28 19:24 ` Oliver Hartkopp
2026-09-28 19:24 ` [PATCH v3 3/3] can: fix unique skb identifier regression under RPS Oliver Hartkopp
2 siblings, 0 replies; 4+ messages in thread
From: Oliver Hartkopp @ 2026-09-28 19:24 UTC (permalink / raw)
To: linux-can; +Cc: Oliver Hartkopp, stable, Oleksij Rempel
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.
With this extension the CAN device specific ml_priv assignment became a
robust indicator to identify a valid CAN device, when can_get_ml_priv()
returns a valid pointer.
This has been used directly by the referenced commit in the CAN specific
j1939 and proc code but not in the other parts of the CAN subsystem.
With the TUN/TAP driver a device's ARPHRD type can be controlled by
userspace independently of its midlayer private data (ml_priv). The
TUNSETLINK ioctl allows a down TUN/TAP device to overwrite its hardware
type to become ARPHRD_CAN while dev->ml_priv remains NULL (uninitialized).
Instead of checking dev->type being the unreliable ARPHRD_CAN value convert
the missing "valid CAN devices" checks 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>
---
net/can/af_can.c | 12 ++++++------
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(+), 16 deletions(-)
diff --git a/net/can/af_can.c b/net/can/af_can.c
index 7bc86b176b4d..ef435f22ac93 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -224,11 +224,11 @@ int can_send(struct sk_buff *skb, int loop)
if (unlikely(skb->len > READ_ONCE(skb->dev->mtu))) {
err = -EMSGSIZE;
goto inval_skb;
}
- if (unlikely(skb->dev->type != ARPHRD_CAN)) {
+ if (unlikely(!can_get_ml_priv(skb->dev))) {
err = -EPERM;
goto inval_skb;
}
if (unlikely(!(skb->dev->flags & IFF_UP))) {
@@ -450,11 +450,11 @@ int can_rx_register(struct net *net, struct net_device *dev, canid_t can_id,
struct can_dev_rcv_lists *dev_rcv_lists;
struct can_rcv_lists_stats *rcv_lists_stats = net->can.rcv_lists_stats;
/* 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)))
return -ENODEV;
@@ -517,11 +517,11 @@ void can_rx_unregister(struct net *net, struct net_device *dev, canid_t can_id,
struct receiver *rcv = NULL;
struct hlist_head *rcv_list;
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)))
return;
@@ -685,11 +685,11 @@ static void can_receive(struct sk_buff *skb, struct net_device *dev)
}
static int can_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt, struct net_device *orig_dev)
{
- if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) ||
+ if (unlikely(!can_get_ml_priv(dev) ||
!can_skb_ext_find(skb) || !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);
kfree_skb_reason(skb, SKB_DROP_REASON_CAN_RX_INVALID_FRAME);
@@ -701,11 +701,11 @@ static int can_rcv(struct sk_buff *skb, struct net_device *dev,
}
static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt, struct net_device *orig_dev)
{
- if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) ||
+ if (unlikely(!can_get_ml_priv(dev) ||
!can_skb_ext_find(skb) || !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);
kfree_skb_reason(skb, SKB_DROP_REASON_CANFD_RX_INVALID_FRAME);
@@ -717,11 +717,11 @@ static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
}
static int canxl_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt, struct net_device *orig_dev)
{
- if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) ||
+ if (unlikely(!can_get_ml_priv(dev) ||
!can_skb_ext_find(skb) || !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);
kfree_skb_reason(skb, SKB_DROP_REASON_CANXL_RX_INVALID_FRAME);
diff --git a/net/can/bcm.c b/net/can/bcm.c
index cd3522ec32c0..940b917e3830 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -52,10 +52,11 @@
#include <linux/netdevice.h>
#include <linux/socket.h>
#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>
#include <linux/slab.h>
#include <linux/workqueue.h>
@@ -1758,11 +1759,11 @@ static int bcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
if (!dev) {
ret = -ENODEV;
goto out_release;
}
- if (dev->type != ARPHRD_CAN) {
+ if (!can_get_ml_priv(dev)) {
dev_put(dev);
ret = -ENODEV;
goto out_release;
}
@@ -1906,11 +1907,11 @@ static void bcm_notify(struct bcm_sock *bo, unsigned long msg,
static int bcm_notifier(struct notifier_block *nb, unsigned long msg,
void *ptr)
{
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;
if (unlikely(bcm_busy_notifier)) /* Check for reentrant bug. */
return NOTIFY_DONE;
@@ -2067,11 +2068,11 @@ static int bcm_connect(struct socket *sock, struct sockaddr_unsized *uaddr, int
dev = dev_get_by_index(net, addr->can_ifindex);
if (!dev) {
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 0ec99f68aa45..d9912dea738b 100644
--- a/net/can/gw.c
+++ b/net/can/gw.c
@@ -50,10 +50,11 @@
#include <linux/net.h>
#include <linux/netdevice.h>
#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>
#include <net/can.h>
#include <net/rtnetlink.h>
@@ -607,11 +608,11 @@ static int cgw_notifier(struct notifier_block *nb,
unsigned long msg, void *ptr)
{
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) {
struct cgw_job *gwj = NULL;
struct hlist_node *nx;
@@ -1158,19 +1159,19 @@ static int cgw_create_job(struct sk_buff *skb, struct nlmsghdr *nlh,
gwj->src.dev = __dev_get_by_index(net, gwj->ccgw.src_idx);
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);
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? */
if (gwj->src.dev == gwj->dst.dev &&
!(gwj->flags & CGW_FLAGS_CAN_IIF_TX_OK)) {
diff --git a/net/can/isotp.c b/net/can/isotp.c
index 0835a4758a72..d3f79efc9c1e 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -63,10 +63,11 @@
#include <linux/netdevice.h>
#include <linux/socket.h>
#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>
#include <linux/slab.h>
#include <net/can.h>
@@ -1604,11 +1605,11 @@ static int isotp_bind(struct socket *sock, struct sockaddr_unsized *uaddr, int l
dev = dev_get_by_index(net, addr->can_ifindex);
if (!dev) {
err = -ENODEV;
goto out;
}
- if (dev->type != ARPHRD_CAN) {
+ if (!can_get_ml_priv(dev)) {
err = -ENODEV;
goto out_put_dev;
}
if (READ_ONCE(dev->mtu) < so->ll.mtu) {
err = -EINVAL;
@@ -1888,11 +1889,11 @@ static void isotp_notify(struct isotp_sock *so, unsigned long msg,
static int isotp_notifier(struct notifier_block *nb, unsigned long msg,
void *ptr)
{
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;
if (unlikely(isotp_busy_notifier)) /* Check for reentrant bug. */
return NOTIFY_DONE;
diff --git a/net/can/raw.c b/net/can/raw.c
index c5596fc9aac5..7c48ff36e6cd 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -339,11 +339,11 @@ static void raw_notify(struct raw_sock *ro, unsigned long msg,
static int raw_notifier(struct notifier_block *nb, unsigned long msg,
void *ptr)
{
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;
if (unlikely(raw_busy_notifier)) /* Check for reentrant bug. */
return NOTIFY_DONE;
@@ -482,11 +482,11 @@ static int raw_bind(struct socket *sock, struct sockaddr_unsized *uaddr, int len
dev = dev_get_by_index(sock_net(sk), addr->can_ifindex);
if (!dev) {
err = -ENODEV;
goto out;
}
- if (dev->type != ARPHRD_CAN) {
+ if (!can_get_ml_priv(dev)) {
err = -ENODEV;
goto out_put_dev;
}
if (!(dev->flags & IFF_UP))
--
2.53.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH v3 3/3] can: fix unique skb identifier regression under RPS
2026-09-28 19:24 [PATCH v3 0/3] CAN netlayer fixes for stable Oliver Hartkopp
2026-09-28 19:24 ` [PATCH v3 1/3] can: remove CAN filters independent from namespace Oliver Hartkopp
2026-09-28 19:24 ` [PATCH v3 2/3] can: convert unreliable ARPHRD_CAN type checks to robust can_get_ml_priv() Oliver Hartkopp
@ 2026-09-28 19:24 ` Oliver Hartkopp
2 siblings, 0 replies; 4+ messages in thread
From: Oliver Hartkopp @ 2026-09-28 19:24 UTC (permalink / raw)
To: linux-can; +Cc: Oliver Hartkopp, Joerg Willmann, stable
Commit d4fb6514ff8e ("can: use skb hash instead of private variable in
headroom") introduced a regression when Receive Packet Steering (RPS)
is enabled.
When RPS is active, the network stack calculates a software hash via
skb_get_hash() before the frame reaches the CAN subsystem. Because the
flow dissector finds no L3/L4 headers in CAN frames, it generates a static
software hash for every CAN packet and sets skb->sw_hash to 1.
Since can_set_skb_uid() originally skipped generating a unique identifier
if skb->hash was already non-zero, it preserved this colliding RPS hash.
If the SLAB allocator subsequently reused the same memory address for a
different skb pointer, raw_rcv() falsely discarded the new, legitimate
frame as a duplicate.
Fix this by moving the CAN skb UID into the CAN skb extension
(struct can_skb_ext::can_skb_uid) instead of using skb->hash.
Additionally force the generation of a new CAN UID for CAN skbs routed via
can-gw and in vxcan.
Fixes: d4fb6514ff8e ("can: use skb hash instead of private variable in headroom")
Reported-by: Joerg Willmann <joe@clnt.de>
Closes: https://lore.kernel.org/linux-can/2859AD3D-C805-41A0-9036-C5E8EE152419@clnt.de/
Cc: stable@vger.kernel.org
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
---
v2: We need a non-zero UID for the cfecho checks in isotp.c
So restore the former while (!(skb->hash)) statement
v3: omit the problematic use of skb->hash reported by sashiko bot.
---
drivers/net/can/vxcan.c | 3 +++
include/linux/can/core.h | 3 ++-
include/linux/can/skb.h | 4 +++-
include/net/can.h | 2 ++
net/can/af_can.c | 29 +++++++++++++++--------------
net/can/gw.c | 3 +++
net/can/isotp.c | 16 ++++++++++------
net/can/raw.c | 10 +++++++---
8 files changed, 45 insertions(+), 25 deletions(-)
diff --git a/drivers/net/can/vxcan.c b/drivers/net/can/vxcan.c
index 9e2e25d02471..51148a81d1d9 100644
--- a/drivers/net/can/vxcan.c
+++ b/drivers/net/can/vxcan.c
@@ -77,10 +77,13 @@ static netdev_tx_t vxcan_xmit(struct sk_buff *oskb, struct net_device *dev)
goto out_unlock;
}
/* reset CAN GW hop counter */
csx->can_gw_hops = 0;
+ /* start with new CAN skb UID in the other namespace */
+ csx->can_skb_uid = 0;
+
skb->pkt_type = PACKET_BROADCAST;
skb->dev = peer;
skb->ip_summed = CHECKSUM_UNNECESSARY;
len = can_skb_get_data_len(skb);
diff --git a/include/linux/can/core.h b/include/linux/can/core.h
index 3287232e3cad..2de74c2b78b6 100644
--- a/include/linux/can/core.h
+++ b/include/linux/can/core.h
@@ -15,10 +15,11 @@
#define _CAN_CORE_H
#include <linux/can.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
+#include <net/can.h>
#define DNAME(dev) ((dev) ? (dev)->name : "any")
/**
* struct can_proto - CAN protocol structure
@@ -56,9 +57,9 @@ extern void can_rx_unregister(struct net *net, struct net_device *dev,
canid_t can_id, canid_t mask,
void (*func)(struct sk_buff *, void *),
void *data);
extern int can_send(struct sk_buff *skb, int loop);
-void can_set_skb_uid(struct sk_buff *skb);
+void can_set_skb_uid(struct can_skb_ext *csx);
void can_sock_destruct(struct sock *sk);
#endif /* !_CAN_CORE_H */
diff --git a/include/linux/can/skb.h b/include/linux/can/skb.h
index a70a02967071..5d27843862fc 100644
--- a/include/linux/can/skb.h
+++ b/include/linux/can/skb.h
@@ -41,12 +41,14 @@ bool can_dropped_invalid_skb(struct net_device *dev, struct sk_buff *skb);
static inline struct can_skb_ext *can_skb_ext_add(struct sk_buff *skb)
{
struct can_skb_ext *csx = skb_ext_add(skb, SKB_EXT_CAN);
/* skb_ext_add() returns uninitialized space */
- if (csx)
+ if (csx) {
csx->can_gw_hops = 0;
+ csx->can_skb_uid = 0;
+ }
return csx;
}
static inline struct can_skb_ext *can_skb_ext_find(struct sk_buff *skb)
diff --git a/include/net/can.h b/include/net/can.h
index 6db9e826f0e0..2b8af2598732 100644
--- a/include/net/can.h
+++ b/include/net/can.h
@@ -15,14 +15,16 @@
* struct can_skb_ext - skb extensions for CAN specific content
* @can_iif: ifindex of the first interface the CAN frame appeared on
* @can_framelen: cached echo CAN frame length for bql
* @can_gw_hops: can-gw CAN frame time-to-live counter
* @can_ext_flags: CAN skb extensions flags
+ * @can_skb_uid: CAN skb UID for raw_rcv and isotp echo handling
*/
struct can_skb_ext {
int can_iif;
u16 can_framelen;
u8 can_gw_hops;
u8 can_ext_flags;
+ u32 can_skb_uid;
};
#endif /* _NET_CAN_H */
diff --git a/net/can/af_can.c b/net/can/af_can.c
index ef435f22ac93..683085f218cf 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -639,17 +639,14 @@ static int can_rcv_filter(struct can_dev_rcv_lists *dev_rcv_lists, struct sk_buf
}
return matches;
}
-void can_set_skb_uid(struct sk_buff *skb)
+void can_set_skb_uid(struct can_skb_ext *csx)
{
- /* create non-zero unique skb identifier together with *skb */
- while (!(skb->hash))
- skb->hash = atomic_inc_return(&skbcounter);
-
- skb->sw_hash = 1;
+ while (!(csx->can_skb_uid))
+ csx->can_skb_uid = atomic_inc_return(&skbcounter);
}
EXPORT_SYMBOL(can_set_skb_uid);
static void can_receive(struct sk_buff *skb, struct net_device *dev)
{
@@ -660,12 +657,10 @@ static void can_receive(struct sk_buff *skb, struct net_device *dev)
/* update statistics */
atomic_long_inc(&pkg_stats->rx_frames);
atomic_long_inc(&pkg_stats->rx_frames_delta);
- can_set_skb_uid(skb);
-
rcu_read_lock();
/* deliver the packet to sockets listening on all devices */
matches = can_rcv_filter(net->can.rx_alldev_list, skb);
@@ -685,51 +680,57 @@ static void can_receive(struct sk_buff *skb, struct net_device *dev)
}
static int can_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt, struct net_device *orig_dev)
{
- if (unlikely(!can_get_ml_priv(dev) ||
- !can_skb_ext_find(skb) || !can_is_can_skb(skb))) {
+ struct can_skb_ext *csx = can_skb_ext_find(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);
kfree_skb_reason(skb, SKB_DROP_REASON_CAN_RX_INVALID_FRAME);
return NET_RX_DROP;
}
+ can_set_skb_uid(csx);
can_receive(skb, dev);
return NET_RX_SUCCESS;
}
static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt, struct net_device *orig_dev)
{
- if (unlikely(!can_get_ml_priv(dev) ||
- !can_skb_ext_find(skb) || !can_is_canfd_skb(skb))) {
+ struct can_skb_ext *csx = can_skb_ext_find(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);
kfree_skb_reason(skb, SKB_DROP_REASON_CANFD_RX_INVALID_FRAME);
return NET_RX_DROP;
}
+ can_set_skb_uid(csx);
can_receive(skb, dev);
return NET_RX_SUCCESS;
}
static int canxl_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt, struct net_device *orig_dev)
{
- if (unlikely(!can_get_ml_priv(dev) ||
- !can_skb_ext_find(skb) || !can_is_canxl_skb(skb))) {
+ struct can_skb_ext *csx = can_skb_ext_find(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);
kfree_skb_reason(skb, SKB_DROP_REASON_CANXL_RX_INVALID_FRAME);
return NET_RX_DROP;
}
+ can_set_skb_uid(csx);
can_receive(skb, dev);
return NET_RX_SUCCESS;
}
/* af_can protocol functions */
diff --git a/net/can/gw.c b/net/can/gw.c
index d9912dea738b..54bb5bd3242a 100644
--- a/net/can/gw.c
+++ b/net/can/gw.c
@@ -526,10 +526,13 @@ static void can_can_gw_rcv(struct sk_buff *skb, void *data)
}
/* put the incremented hop counter in the cloned skb */
ncsx->can_gw_hops = csx->can_gw_hops + 1;
+ /* force a new CAN UID generation for the routed frame */
+ ncsx->can_skb_uid = 0;
+
/* first processing of this CAN frame -> adjust to private hop limit */
if (gwj->limit_hops && ncsx->can_gw_hops == 1)
ncsx->can_gw_hops = max_hops - gwj->limit_hops + 1;
nskb->dev = gwj->dst.dev;
diff --git a/net/can/isotp.c b/net/can/isotp.c
index d3f79efc9c1e..3aadfd787a03 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -890,11 +890,11 @@ static void isotp_send_cframe(struct isotp_sock *so)
}
csx->can_iif = dev->ifindex;
/* set uid in tx skb to identify CF echo frames */
- can_set_skb_uid(skb);
+ can_set_skb_uid(csx);
cf = (struct canfd_frame *)skb->data;
skb_put_zero(skb, so->ll.mtu);
/* create consecutive frame */
@@ -916,11 +916,11 @@ static void isotp_send_cframe(struct isotp_sock *so)
old_cfecho = READ_ONCE(so->cfecho);
if (old_cfecho)
pr_notice_once("can-isotp: cfecho is %08X != 0\n", old_cfecho);
/* set consecutive frame echo tag */
- WRITE_ONCE(so->cfecho, skb->hash);
+ WRITE_ONCE(so->cfecho, csx->can_skb_uid);
/* send frame with local echo enabled */
can_send_ret = can_send(skb, 1);
if (can_send_ret) {
pr_notice_once("can-isotp: %s: can_send_ret %pe\n",
@@ -968,22 +968,26 @@ static void isotp_create_fframe(struct canfd_frame *cf, struct isotp_sock *so,
static void isotp_rcv_echo(struct sk_buff *skb, void *data)
{
struct sock *sk = (struct sock *)data;
struct isotp_sock *so = isotp_sk(sk);
+ struct can_skb_ext *csx = can_skb_ext_find(skb);
/* only handle my own local echo CF/SF skb's (no FF!) */
if (skb->sk != sk)
return;
+ if (!csx)
+ return;
+
/* unlike isotp_rcv_fc()/isotp_rcv_cf(), not already under so->rx_lock
* (no isotp_rcv() caller here), so take it ourselves
*/
spin_lock(&so->rx_lock);
/* so->cfecho may since belong to a new transfer; recheck under lock */
- if (READ_ONCE(so->cfecho) != skb->hash)
+ if (READ_ONCE(so->cfecho) != csx->can_skb_uid)
goto out_unlock;
/* cancel local echo timeout */
hrtimer_cancel(&so->echotimer);
@@ -1221,11 +1225,11 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
}
csx->can_iif = dev->ifindex;
/* set uid in tx skb to identify CF echo frames */
- can_set_skb_uid(skb);
+ can_set_skb_uid(csx);
so->tx.len = size;
so->tx.idx = 0;
cf = (struct canfd_frame *)skb->data;
@@ -1260,11 +1264,11 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
cf->data[SF_PCI_SZ4 + ae] = size;
else
cf->data[ae] |= size;
/* set CF echo tag for isotp_rcv_echo() (SF-mode) */
- WRITE_ONCE(so->cfecho, skb->hash);
+ WRITE_ONCE(so->cfecho, csx->can_skb_uid);
} else {
/* send first frame */
isotp_create_fframe(cf, so, ae);
@@ -1277,11 +1281,11 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
/* disable wait for FCs due to activated block size */
so->txfc.bs = 0;
/* set CF echo tag for isotp_rcv_echo() (CF-mode) */
- WRITE_ONCE(so->cfecho, skb->hash);
+ WRITE_ONCE(so->cfecho, csx->can_skb_uid);
} else {
/* standard flow control check */
new_state = ISOTP_WAIT_FIRST_FC;
/* start timeout for FC */
diff --git a/net/can/raw.c b/net/can/raw.c
index 7c48ff36e6cd..0a3378476f0a 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -75,11 +75,11 @@ MODULE_ALIAS("can-proto-1");
* storing the single filter in dfilter, to avoid using dynamic memory.
*/
struct uniqframe {
const struct sk_buff *skb;
- u32 hash;
+ u32 can_skb_uid;
unsigned int join_rx_count;
};
struct raw_sock {
struct sock sk;
@@ -131,16 +131,20 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
struct sock *sk = (struct sock *)data;
struct raw_sock *ro = raw_sk(sk);
enum skb_drop_reason reason;
struct sockaddr_can *addr;
struct sk_buff *skb;
+ struct can_skb_ext *csx = can_skb_ext_find(oskb);
unsigned int *pflags;
/* check the received tx sock reference */
if (!ro->recv_own_msgs && oskb->sk == sk)
return;
+ if (!csx)
+ return;
+
/* make sure to not pass oversized frames to the socket */
if (!ro->fd_frames && can_is_canfd_skb(oskb))
return;
if (can_is_canxl_skb(oskb)) {
@@ -163,21 +167,21 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
}
}
/* eliminate multiple filter matches for the same skb */
if (this_cpu_ptr(ro->uniq)->skb == oskb &&
- this_cpu_ptr(ro->uniq)->hash == oskb->hash) {
+ this_cpu_ptr(ro->uniq)->can_skb_uid == csx->can_skb_uid) {
if (!ro->join_filters)
return;
this_cpu_inc(ro->uniq->join_rx_count);
/* drop frame until all enabled filters matched */
if (this_cpu_ptr(ro->uniq)->join_rx_count < ro->count)
return;
} else {
this_cpu_ptr(ro->uniq)->skb = oskb;
- this_cpu_ptr(ro->uniq)->hash = oskb->hash;
+ this_cpu_ptr(ro->uniq)->can_skb_uid = csx->can_skb_uid;
this_cpu_ptr(ro->uniq)->join_rx_count = 1;
/* drop first frame to check all enabled filters? */
if (ro->join_filters && ro->count > 1)
return;
}
--
2.53.0
^ permalink raw reply related [flat|nested] 4+ messages in thread