Commit 0ae89beb authored by Oliver Hartkopp's avatar Oliver Hartkopp Committed by David S. Miller
Browse files

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
376c7311 (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: default avatarOliver Hartkopp <socketcan@hartkopp.net>
Tested-by: default avatarAndre Naujoks <nautsch2@gmail.com>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 920a0fde

drivers/net/can/dev.c

+3 −12
Original line number Diff line number Diff line
@@ -323,19 +323,10 @@ void can_put_echo_skb(struct sk_buff *skb, struct net_device *dev, 
	}



	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);

		skb = can_create_echo_skb(skb);

		if (!skb)

			return;

		} else

			skb_orphan(skb);



		skb->sk = srcsk;



		/* make settings for echo to reduce code in irq context */

		skb->protocol = htons(ETH_P_CAN);

drivers/net/can/janz-ican3.c

+4 −14
Original line number Diff line number Diff line
@@ -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_handle_message(struct ican3_dev *mod, struct ican3_msg *msg) 
 */

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);

	skb = can_create_echo_skb(skb);

	if (!skb)

		return;

	} else {

		skb_orphan(skb);

	}



	skb->sk = srcsk;



	/* save this skb for tx interrupt echo handling */

	skb_queue_tail(&mod->echoq, skb);

drivers/net/can/vcan.c

+4 −5
Original line number Diff line number Diff line
@@ -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 @@ static netdev_tx_t vcan_tx(struct sk_buff *skb, struct net_device *dev) 
			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;

}

include/linux/can/skb.h

+38 −0
Original line number Diff line number Diff line
@@ -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 @@ static inline void can_skb_reserve(struct sk_buff *skb) 
	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 */

net/can/af_can.c

+2 −1
Original line number Diff line number Diff line
@@ -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 @@ int can_send(struct sk_buff *skb, int loop) 
				return -ENOMEM;

			}



			newskb->sk = skb->sk;

			can_skb_set_owner(newskb, skb->sk);

			newskb->ip_summed = CHECKSUM_UNNECESSARY;

			newskb->pkt_type = PACKET_BROADCAST;

		}

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