can: add destructor for self generated skbs
Self generated skbuffs in net/can/bcm.c are setting a skb->sk reference but
no explicit destructor which is enforced since Linux 3.11 with commit
376c7311bdb6 (net: add a temporary sanity check in skb_orphan()).
This patch adds some helper functions to make sure that a destructor is
properly defined when a sock reference is assigned to a CAN related skb.
To create an unshared skb owned by the original sock a common helper function
has been introduced to replace open coded functions to create CAN echo skbs.
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Tested-by: Andre Naujoks <nautsch2@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
index 13a9098..fc59bc6 100644
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -323,19 +323,10 @@
}
if (!priv->echo_skb[idx]) {
- struct sock *srcsk = skb->sk;
- if (atomic_read(&skb->users) != 1) {
- struct sk_buff *old_skb = skb;
-
- skb = skb_clone(old_skb, GFP_ATOMIC);
- kfree_skb(old_skb);
- if (!skb)
- return;
- } else
- skb_orphan(skb);
-
- skb->sk = srcsk;
+ skb = can_create_echo_skb(skb);
+ if (!skb)
+ return;
/* make settings for echo to reduce code in irq context */
skb->protocol = htons(ETH_P_CAN);
diff --git a/drivers/net/can/janz-ican3.c b/drivers/net/can/janz-ican3.c
index e24e669..2124c679 100644
--- a/drivers/net/can/janz-ican3.c
+++ b/drivers/net/can/janz-ican3.c
@@ -18,6 +18,7 @@
#include <linux/netdevice.h>
#include <linux/can.h>
#include <linux/can/dev.h>
+#include <linux/can/skb.h>
#include <linux/can/error.h>
#include <linux/mfd/janz.h>
@@ -1133,20 +1134,9 @@
*/
static void ican3_put_echo_skb(struct ican3_dev *mod, struct sk_buff *skb)
{
- struct sock *srcsk = skb->sk;
-
- if (atomic_read(&skb->users) != 1) {
- struct sk_buff *old_skb = skb;
-
- skb = skb_clone(old_skb, GFP_ATOMIC);
- kfree_skb(old_skb);
- if (!skb)
- return;
- } else {
- skb_orphan(skb);
- }
-
- skb->sk = srcsk;
+ skb = can_create_echo_skb(skb);
+ if (!skb)
+ return;
/* save this skb for tx interrupt echo handling */
skb_queue_tail(&mod->echoq, skb);
diff --git a/drivers/net/can/vcan.c b/drivers/net/can/vcan.c
index 0a2a5ee..4e94057 100644
--- a/drivers/net/can/vcan.c
+++ b/drivers/net/can/vcan.c
@@ -46,6 +46,7 @@
#include <linux/if_ether.h>
#include <linux/can.h>
#include <linux/can/dev.h>
+#include <linux/can/skb.h>
#include <linux/slab.h>
#include <net/rtnetlink.h>
@@ -109,25 +110,23 @@
stats->rx_packets++;
stats->rx_bytes += cfd->len;
}
- kfree_skb(skb);
+ consume_skb(skb);
return NETDEV_TX_OK;
}
/* perform standard echo handling for CAN network interfaces */
if (loop) {
- struct sock *srcsk = skb->sk;
- skb = skb_share_check(skb, GFP_ATOMIC);
+ skb = can_create_echo_skb(skb);
if (!skb)
return NETDEV_TX_OK;
/* receive with packet counting */
- skb->sk = srcsk;
vcan_rx(skb, dev);
} else {
/* no looped packets => no counting */
- kfree_skb(skb);
+ consume_skb(skb);
}
return NETDEV_TX_OK;
}
diff --git a/include/linux/can/skb.h b/include/linux/can/skb.h
index 2f0543f..f9bbbb4 100644
--- a/include/linux/can/skb.h
+++ b/include/linux/can/skb.h
@@ -11,7 +11,9 @@
#define CAN_SKB_H
#include <linux/types.h>
+#include <linux/skbuff.h>
#include <linux/can.h>
+#include <net/sock.h>
/*
* The struct can_skb_priv is used to transport additional information along
@@ -42,4 +44,40 @@
skb_reserve(skb, sizeof(struct can_skb_priv));
}
+static inline void can_skb_destructor(struct sk_buff *skb)
+{
+ sock_put(skb->sk);
+}
+
+static inline void can_skb_set_owner(struct sk_buff *skb, struct sock *sk)
+{
+ if (sk) {
+ sock_hold(sk);
+ skb->destructor = can_skb_destructor;
+ skb->sk = sk;
+ }
+}
+
+/*
+ * returns an unshared skb owned by the original sock to be echo'ed back
+ */
+static inline struct sk_buff *can_create_echo_skb(struct sk_buff *skb)
+{
+ if (skb_shared(skb)) {
+ struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
+
+ if (likely(nskb)) {
+ can_skb_set_owner(nskb, skb->sk);
+ consume_skb(skb);
+ return nskb;
+ } else {
+ kfree_skb(skb);
+ return NULL;
+ }
+ }
+
+ /* we can assume to have an unshared skb with proper owner */
+ return skb;
+}
+
#endif /* CAN_SKB_H */
diff --git a/net/can/af_can.c b/net/can/af_can.c
index d249874..a27f8aa 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -57,6 +57,7 @@
#include <linux/skbuff.h>
#include <linux/can.h>
#include <linux/can/core.h>
+#include <linux/can/skb.h>
#include <linux/ratelimit.h>
#include <net/net_namespace.h>
#include <net/sock.h>
@@ -290,7 +291,7 @@
return -ENOMEM;
}
- newskb->sk = skb->sk;
+ can_skb_set_owner(newskb, skb->sk);
newskb->ip_summed = CHECKSUM_UNNECESSARY;
newskb->pkt_type = PACKET_BROADCAST;
}
diff --git a/net/can/bcm.c b/net/can/bcm.c
index 3fc737b..dcb75c0 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -268,7 +268,7 @@
/* send with loopback */
skb->dev = dev;
- skb->sk = op->sk;
+ can_skb_set_owner(skb, op->sk);
can_send(skb, 1);
/* update statistics */
@@ -1223,7 +1223,7 @@
can_skb_prv(skb)->ifindex = dev->ifindex;
skb->dev = dev;
- skb->sk = sk;
+ can_skb_set_owner(skb, sk);
err = can_send(skb, 1); /* send with loopback */
dev_put(dev);