On 06/01/2016 11:07 PM, Stefan Hajnoczi wrote:
On Sat, May 28, 2016 at 06:29:05PM +0200, ggar...@abra.uab.cat wrote:
From: Gerard Garcia <ggar...@deic.uab.cat>
Signed-off-by: Gerard Garcia <ggar...@deic.uab.cat>
---
include/net/af_vsock.h | 13 ++++++
include/uapi/linux/if_arp.h | 1 +
net/vmw_vsock/af_vsock.c | 105 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 119 insertions(+)
diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index 15694c9..c4593d8 100644
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h
@@ -187,4 +187,17 @@ struct sock *vsock_find_connected_socket(struct
sockaddr_vm *src,
struct sockaddr_vm *dst);
void vsock_for_each_connected_socket(void (*fn)(struct sock *sk));
+/**** TAP ****/
+
+struct vsock_tap {
+ struct net_device *dev;
+ struct module *module;
+ struct list_head list;
+};
+
+extern int vsock_init_tap(void);
+extern int vsock_add_tap(struct vsock_tap *vt);
+extern int vsock_remove_tap(struct vsock_tap *vt);
+extern void vsock_deliver_tap(struct sk_buff *skb);
The other function prototypes in this header don't use "extern" either.
Please drop for consistency.
Ok
+
#endif /* __AF_VSOCK_H__ */
diff --git a/include/uapi/linux/if_arp.h b/include/uapi/linux/if_arp.h
index 4d024d7..869262a 100644
--- a/include/uapi/linux/if_arp.h
+++ b/include/uapi/linux/if_arp.h
@@ -95,6 +95,7 @@
#define ARPHRD_IP6GRE 823 /* GRE over IPv6 */
#define ARPHRD_NETLINK 824 /* Netlink header
*/
#define ARPHRD_6LOWPAN 825 /* IPv6 over LoWPAN
*/
+#define ARPHRD_VSOCKMON 826 /* Vsock monitor header */
Previous lines use a tab character (^I) before the numeric constant.
Please follow that style for consistency.
Ok
I suggest calling it just ARPHRD_VSOCK. Netlink also uses
ARPHRD_NETLINK instead of ARPHRD_NLMON.
We define a new header used exclusively by the vsockmon device, nlmon
copies the netlink header entirely.
I'm not sure if we should *link* the ARPHRD_VSOCK identifier to the
vsockmon header.
#define ARPHRD_VOID 0xFFFF /* Void type, nothing is known */
#define ARPHRD_NONE 0xFFFE /* zero header length */
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 6b158ab..ec7a05d 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -96,6 +96,7 @@
#include <linux/unistd.h>
#include <linux/wait.h>
#include <linux/workqueue.h>
+#include <linux/if_arp.h>
#include <net/sock.h>
#include <net/af_vsock.h>
@@ -2012,6 +2013,110 @@ const struct vsock_transport *vsock_core_get_transport(void)
}
EXPORT_SYMBOL_GPL(vsock_core_get_transport);
+/**** TAP ****/
Feel free to put this in a separate source file. The Kbuild can link
multiple objects into a single kernel module. That would be cleaner
than using a big comment to separate it from af_vsock.c code.
I'm following the af_vsock.c style, where different logic is separated
using this style of comments. It is not a lot of code
so I thought it would be cleaner to have it in the same file.
I wonder whether this tap mechanism should be generic so that netlink,
vsock, and other address families can reuse the code. This is basically
copied from netlink.
+static DEFINE_SPINLOCK(vsock_tap_lock);
+static struct list_head vsock_tap_all __read_mostly;
+
+int vsock_init_tap(void) {
+ INIT_LIST_HEAD(&vsock_tap_all);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(vsock_init_tap);
Can you use LIST_HEAD_INIT() on the vsock_tap_all declaration line to
eliminate the need for vsock_init_tap() completely?
Yes, I'll do that. I though we may need to do more initialization at
some point, but for now it is better to just
statically initialize it.
+
+int vsock_add_tap(struct vsock_tap *vt) {
+ if (unlikely(vt->dev->type != ARPHRD_VSOCKMON))
+ return -EINVAL;
+
+ spin_lock(&vsock_tap_lock);
+ list_add_rcu(&vt->list, &vsock_tap_all);
+ spin_unlock(&vsock_tap_lock);
+
+ __module_get(vt->module);
It's slightly safer to get the module before publishing it on the list.
But in practice I guess the caller is the module so the module won't
disappear underneath us.
This function is equal to the function in af_netlink.c used by nlmon. As
you said, in practice the caller is the module
so it won't disappear.
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(vsock_add_tap);
+
+int __vsock_remove_tap(struct vsock_tap *vt) {
+ bool found = false;
+ struct vsock_tap *tmp;
+
+ spin_lock(&vsock_tap_lock);
+
+ list_for_each_entry(tmp, &vsock_tap_all, list) {
+ if (vt == tmp) {
+ list_del_rcu(&vt->list);
+ found = true;
+ goto out;
+ }
+ }
+
+ pr_warn("__vsock_remove_tap: %p not found\n", vt);
+out:
+ spin_unlock(&vsock_tap_lock);
+
+ if (found)
+ module_put(vt->module);
+
+ return found ? 0 : -ENODEV;
+}
+
+int vsock_remove_tap(struct vsock_tap *vt)
+{
+ int ret;
+
+ ret = __vsock_remove_tap(vt);
+ synchronize_net();
module_put() should be called after synchronize_net(). That way we
guarantee that no one is still accessing vt when the module is put. The
caller is probably the module though, so maybe there is an implicit
reference...
Also, it is equal to the function in af_netlink.c used by nlmon. And as
before, this function is supposed
to be called from the same module so it can't disappear before calling
synchronize_net().
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(vsock_remove_tap);
+
+static int __vsock_deliver_tap_skb(struct sk_buff *skb,
+ struct net_device *dev)
+{
+ struct sk_buff *vskb;
+ int ret = 0;
+
+ if (skb) {
+ dev_hold(dev);
+ vskb = skb_clone(skb, GFP_ATOMIC);
You must handle the case where skb_clone() returns NULL. In other
words, we don't have enough memory to capture the packet and just return
-ENOMEM.
You are right!
+ vskb->dev = dev;
+ vskb->pkt_type = PACKET_USER;
I'm not sure if PACKET_USER is correct (or if pkt_type matters at all).
PACKET_USER/PACKET_KERNEL seems to be purely a netlink concept to
distinguish netlink packets originating from the kernel or userspace.
AF_VSOCK is more like Ethernet where packets come from the host itself
or from a VM. I would consider PACKET_HOST and PACKET_OTHERHOST.
I'm not sure either if pkt_type matters. I haven't found any code that
uses it so I'll just leave it unset.
+ ret = dev_queue_xmit(vskb);
+ if (unlikely(ret > 0))
+ ret = net_xmit_errno(ret);
+
+ dev_put(dev);
+ }
+
+ return ret;
+}
+
+static void __vsock_deliver_tap(struct sk_buff *skb)
+{
+ int ret;
+ struct vsock_tap *tmp;
+
+ list_for_each_entry_rcu(tmp, &vsock_tap_all, list) {
+ ret = __vsock_deliver_tap_skb(skb, tmp->dev);
+ if (unlikely(ret))
+ break;
+ }
+}
+
+void vsock_deliver_tap(struct sk_buff *skb)
+{
+ rcu_read_lock();
+
+ if (unlikely(!list_empty(&vsock_tap_all)))
+ __vsock_deliver_tap(skb);
+
+ rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(vsock_deliver_tap);
+
MODULE_AUTHOR("VMware, Inc.");
MODULE_DESCRIPTION("VMware Virtual Socket Family");
MODULE_VERSION("1.0.1.0-k");
--
2.8.3
