[PATCH net,1/1] hyperv: Add support for setting MAC from within guests

[Haiyang Zhang <haiyangz@microsoft.com>]

This adds support for setting synthetic NIC MAC address from within Linux
guests. Before using this feature, the option "spoofing of MAC address"
should be enabled at the Hyper-V manager / Settings of the synthetic
NIC.

Thanks to Kin Cho <kcho@infoblox.com> for the initial implementation and
tests. And, thanks to Long Li <longli@microsoft.com> for the debugging
works.

Reported-and-tested-by: Kin Cho <kcho@infoblox.com>
Reported-by: Long Li <longli@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/net/hyperv/hyperv_net.h   |    1 +
 drivers/net/hyperv/netvsc_drv.c   |   30 +++++++++++++-
 drivers/net/hyperv/rndis_filter.c |   79 +++++++++++++++++++++++++++++++++++++
 3 files changed, 109 insertions(+), 1 deletions(-)

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index 2857ab0..95ceb35 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -131,6 +131,7 @@ int rndis_filter_send(struct hv_device *dev,
 			struct hv_netvsc_packet *pkt);
 
 int rndis_filter_set_packet_filter(struct rndis_device *dev, u32 new_filter);
+int rndis_filter_set_device_mac(struct hv_device *hdev, char *mac);
 
 
 #define NVSP_INVALID_PROTOCOL_VERSION	((u32)0xFFFFFFFF)
diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 8f8ed33..8e23c08 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -341,6 +341,34 @@ static int netvsc_change_mtu(struct net_device *ndev, int mtu)
 	return 0;
 }
 
+
+static int netvsc_set_mac_addr(struct net_device *ndev, void *p)
+{
+	struct net_device_context *ndevctx = netdev_priv(ndev);
+	struct hv_device *hdev =  ndevctx->device_ctx;
+	struct sockaddr *addr = p;
+	char save_adr[14];
+	unsigned char save_aatype;
+	int err;
+
+	memcpy(save_adr, ndev->dev_addr, ETH_ALEN);
+	save_aatype = ndev->addr_assign_type;
+
+	err = eth_mac_addr(ndev, p);
+	if (err != 0)
+		return err;
+
+	err = rndis_filter_set_device_mac(hdev, addr->sa_data);
+	if (err != 0) {
+		/* roll back to saved MAC */
+		memcpy(ndev->dev_addr, save_adr, ETH_ALEN);
+		ndev->addr_assign_type = save_aatype;
+	}
+
+	return err;
+}
+
+
 static const struct ethtool_ops ethtool_ops = {
 	.get_drvinfo	= netvsc_get_drvinfo,
 	.get_link	= ethtool_op_get_link,
@@ -353,7 +381,7 @@ static const struct net_device_ops device_ops = {
 	.ndo_set_rx_mode =		netvsc_set_multicast_list,
 	.ndo_change_mtu =		netvsc_change_mtu,
 	.ndo_validate_addr =		eth_validate_addr,
-	.ndo_set_mac_address =		eth_mac_addr,
+	.ndo_set_mac_address =		netvsc_set_mac_addr,
 };
 
 /*
diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index 981ebb1..fbf5394 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -27,6 +27,7 @@
 #include <linux/if_ether.h>
 #include <linux/netdevice.h>
 #include <linux/if_vlan.h>
+#include <linux/nls.h>
 
 #include "hyperv_net.h"
 
@@ -47,6 +48,7 @@ struct rndis_request {
 	struct hv_page_buffer buf;
 	/* FIXME: We assumed a fixed size request here. */
 	struct rndis_message request_msg;
+	u8 ext[100];
 };
 
 static void rndis_filter_send_completion(void *ctx);
@@ -511,6 +513,83 @@ static int rndis_filter_query_device_mac(struct rndis_device *dev)
 				      dev->hw_mac_adr, &size);
 }
 
+#define NWADR_STR "NetworkAddress"
+#define NWADR_STRLEN 14
+
+int rndis_filter_set_device_mac(struct hv_device *hdev, char *mac)
+{
+	struct netvsc_device *nvdev = hv_get_drvdata(hdev);
+	struct rndis_device *rdev = nvdev->extension;
+	struct net_device *ndev = nvdev->ndev;
+	struct rndis_request *request;
+	struct rndis_set_request *set;
+	struct rndis_config_parameter_info *cpi;
+	wchar_t *cfg_nwadr, *cfg_mac;
+	struct rndis_set_complete *set_complete;
+	char macstr[2*ETH_ALEN+1];
+	u32 extlen = sizeof(struct rndis_config_parameter_info) +
+		2*NWADR_STRLEN + 4*ETH_ALEN;
+	int ret, t;
+
+	request = get_rndis_request(rdev, RNDIS_MSG_SET,
+		RNDIS_MESSAGE_SIZE(struct rndis_set_request) + extlen);
+	if (!request)
+		return -ENOMEM;
+
+	set = &request->request_msg.msg.set_req;
+	set->oid = RNDIS_OID_GEN_RNDIS_CONFIG_PARAMETER;
+	set->info_buflen = extlen;
+	set->info_buf_offset = sizeof(struct rndis_set_request);
+	set->dev_vc_handle = 0;
+
+	cpi = (struct rndis_config_parameter_info *)((ulong)set +
+		set->info_buf_offset);
+	cpi->parameter_name_offset =
+		sizeof(struct rndis_config_parameter_info);
+	/* Multiply by 2 because host needs 2 bytes (utf16) for each char */
+	cpi->parameter_name_length = 2*NWADR_STRLEN;
+	cpi->parameter_type = RNDIS_CONFIG_PARAM_TYPE_STRING;
+	cpi->parameter_value_offset =
+		cpi->parameter_name_offset + cpi->parameter_name_length;
+	/* Multiply by 4 because each MAC byte displayed as 2 utf16 chars */
+	cpi->parameter_value_length = 4*ETH_ALEN;
+
+	cfg_nwadr = (wchar_t *)((ulong)cpi + cpi->parameter_name_offset);
+	cfg_mac = (wchar_t *)((ulong)cpi + cpi->parameter_value_offset);
+	ret = utf8s_to_utf16s(NWADR_STR, NWADR_STRLEN, UTF16_HOST_ENDIAN,
+			      cfg_nwadr, NWADR_STRLEN);
+	if (ret < 0)
+		goto cleanup;
+	snprintf(macstr, 2*ETH_ALEN+1, "%pm", mac);
+	ret = utf8s_to_utf16s(macstr, 2*ETH_ALEN, UTF16_HOST_ENDIAN,
+			      cfg_mac, 2*ETH_ALEN);
+	if (ret < 0)
+		goto cleanup;
+
+	ret = rndis_filter_send_request(rdev, request);
+	if (ret != 0)
+		goto cleanup;
+
+	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
+	if (t == 0) {
+		netdev_err(ndev, "timeout before we got a set response...\n");
+		/*
+		 * can't put_rndis_request, since we may still receive a
+		 * send-completion.
+		 */
+		return -EBUSY;
+	} else {
+		set_complete = &request->response_msg.msg.set_complete;
+		if (set_complete->status != RNDIS_STATUS_SUCCESS)
+			ret = -EINVAL;
+	}
+
+cleanup:
+	put_rndis_request(rdev, request);
+	return ret;
+}
+
+
 static int rndis_filter_query_device_link_status(struct rndis_device *dev)
 {
 	u32 size = sizeof(u32);
-- 
1.7.4.1