[PATCH] appletalk: Pass IP-over-DDP packets through when 'ipddp0' interface is not present
From: Adam Seering <hidden>
Date: 2016-01-15 04:49:13
Let userspace programs transmit and receive raw IP-over-DDP packets with a kernel where "ipddp" was compiled as a module but is not loaded (so no "ipddp0" network interface is exposed). This makes the "module is unloaded" behavior match the "module was never compiled" behavior. Signed-off-by: Adam Seering <redacted> --- This is a small proposed change to the ddp code. It's also my first attempt at a kernel patch; I'd appreciate any feedback or discussion. I'm working on the Linux "macipgw" port; it duplicates some functionality of the "ipddp" module, but the latter depends on userspace utilities which I can no longer find up-to-date working copies of?
diff --git a/net/appletalk/ddp.c b/net/appletalk/ddp.c
index d5871ac..d30e55f 100644
--- a/net/appletalk/ddp.c
+++ b/net/appletalk/ddp.c@@ -1284,17 +1284,10 @@ static __inline__ int is_ip_over_ddp(struct sk_buff *skb) return skb->data[12] == 22; } -static int handle_ip_over_ddp(struct sk_buff *skb) +static int handle_ip_over_ddp(struct sk_buff *skb, struct net_device *dev) { - struct net_device *dev = __dev_get_by_name(&init_net, "ipddp0"); struct net_device_stats *stats; - /* This needs to be able to handle ipddp"N" devices */ - if (!dev) { - kfree_skb(skb); - return NET_RX_DROP; - } - skb->protocol = htons(ETH_P_IP); skb_pull(skb, 13); skb->dev = dev;
@@ -1308,7 +1301,7 @@ static int handle_ip_over_ddp(struct sk_buff *skb) #else /* make it easy for gcc to optimize this test out, i.e. kill the code */ #define is_ip_over_ddp(skb) 0 -#define handle_ip_over_ddp(skb) 0 +#define handle_ip_over_ddp(skb, dev) 0 #endif static int atalk_route_packet(struct sk_buff *skb, struct net_device *dev,
@@ -1418,6 +1411,8 @@ static int atalk_rcv(struct sk_buff *skb, struct net_device *dev, struct sock *sock; struct atalk_iface *atif; struct sockaddr_at tosat; + struct net_device *ipddp_dev; + int origlen; __u16 len_hops;
@@ -1473,9 +1468,14 @@ static int atalk_rcv(struct sk_buff *skb, struct net_device *dev, return atalk_route_packet(skb, dev, ddp, len_hops, origlen); } - /* if IP over DDP is not selected this code will be optimized out */ - if (is_ip_over_ddp(skb)) - return handle_ip_over_ddp(skb); + /* if IP over DDP is not selected this code should be optimized out */ + if (is_ip_over_ddp(skb)) { + ipddp_dev = __dev_get_by_name(&init_net, "ipddp0"); + + /* This needs to be able to handle ipddp"N" devices */ + if (ipddp_dev) + return handle_ip_over_ddp(skb, ipddp_dev); + } /* * Which socket - atalk_search_socket() looks for a *full match* * of the <net, node, port> tuple.