netvsc: use RCU to protect inner device structure

The netvsc driver has an internal structure (netvsc_device) which
is created when device is opened and released when device is closed.
And also opened/released when MTU or number of channels change.

Since this is referenced in the receive and transmit path, it is
safer to use RCU to protect/prevent use after free problems.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index a33f2ee860442f256f3c5537ac41a830ee6014ec..0ade21f95d7183d09c6ff9c58f15266c05295db8 100644 (file)
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -686,7 +686,7 @@ struct net_device_context {
        /* point back to our device context */
        struct hv_device *device_ctx;
        /* netvsc_device */
-       struct netvsc_device *nvdev;
+       struct netvsc_device __rcu *nvdev;
        /* reconfigure work */
        struct delayed_work dwork;
        /* last reconfig time */
@@ -780,6 +780,8 @@ struct netvsc_device {
        atomic_t open_cnt;
 
        struct netvsc_channel chan_table[VRSS_CHANNEL_MAX];
+
+       struct rcu_head rcu;
 };
 
 static inline struct netvsc_device *

diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 727762d0f13b0c02aea57c579d699a75243ec915..ab9118d620abba410fc071850b1f11bd14fac129 100644 (file)
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -80,8 +80,10 @@ static struct netvsc_device *alloc_net_device(void)
        return net_device;
 }
 
-static void free_netvsc_device(struct netvsc_device *nvdev)
+static void free_netvsc_device(struct rcu_head *head)
 {
+       struct netvsc_device *nvdev
+               = container_of(head, struct netvsc_device, rcu);
        int i;
 
        for (i = 0; i < VRSS_CHANNEL_MAX; i++)
@@ -90,6 +92,10 @@ static void free_netvsc_device(struct netvsc_device *nvdev)
        kfree(nvdev);
 }
 
+static void free_netvsc_device_rcu(struct netvsc_device *nvdev)
+{
+       call_rcu(&nvdev->rcu, free_netvsc_device);
+}
 
 static struct netvsc_device *get_outbound_net_device(struct hv_device *device)
 {
@@ -551,7 +557,7 @@ void netvsc_device_remove(struct hv_device *device)
 
        netvsc_disconnect_vsp(device);
 
-       net_device_ctx->nvdev = NULL;
+       RCU_INIT_POINTER(net_device_ctx->nvdev, NULL);
 
        /*
         * At this point, no one should be accessing net_device
@@ -566,7 +572,7 @@ void netvsc_device_remove(struct hv_device *device)
                napi_disable(&net_device->chan_table[i].napi);
 
        /* Release all resources */
-       free_netvsc_device(net_device);
+       free_netvsc_device_rcu(net_device);
 }
 
 #define RING_AVAIL_PERCENT_HIWATER 20
@@ -1322,7 +1328,7 @@ int netvsc_device_add(struct hv_device *device,
         */
        wmb();
 
-       net_device_ctx->nvdev = net_device;
+       rcu_assign_pointer(net_device_ctx->nvdev, net_device);
 
        /* Connect with the NetVsp */
        ret = netvsc_connect_vsp(device);
@@ -1341,7 +1347,7 @@ close:
        vmbus_close(device->channel);
 
 cleanup:
-       free_netvsc_device(net_device);
+       free_netvsc_device(&net_device->rcu);
 
        return ret;
 }

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 2f9de2e9f38e93464676fae4c12ac8f81dca2ad5..d8a70d07eeecd0dd967cfb884ffbe30ac6483fca 100644 (file)
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -62,7 +62,7 @@ static void do_set_multicast(struct work_struct *w)
                container_of(w, struct net_device_context, work);
        struct hv_device *device_obj = ndevctx->device_ctx;
        struct net_device *ndev = hv_get_drvdata(device_obj);
-       struct netvsc_device *nvdev = ndevctx->nvdev;
+       struct netvsc_device *nvdev = rcu_dereference(ndevctx->nvdev);
        struct rndis_device *rdev;
 
        if (!nvdev)
@@ -116,7 +116,7 @@ static int netvsc_open(struct net_device *net)
 static int netvsc_close(struct net_device *net)
 {
        struct net_device_context *net_device_ctx = netdev_priv(net);
-       struct netvsc_device *nvdev = net_device_ctx->nvdev;
+       struct netvsc_device *nvdev = rtnl_dereference(net_device_ctx->nvdev);
        int ret;
        u32 aread, awrite, i, msec = 10, retry = 0, retry_max = 20;
        struct vmbus_channel *chn;
@@ -637,9 +637,9 @@ int netvsc_recv_callback(struct net_device *net,
                         const struct ndis_pkt_8021q_info *vlan)
 {
        struct net_device_context *net_device_ctx = netdev_priv(net);
-       struct netvsc_device *net_device = net_device_ctx->nvdev;
+       struct netvsc_device *net_device;
        u16 q_idx = channel->offermsg.offer.sub_channel_index;
-       struct netvsc_channel *nvchan = &net_device->chan_table[q_idx];
+       struct netvsc_channel *nvchan;
        struct net_device *vf_netdev;
        struct sk_buff *skb;
        struct netvsc_stats *rx_stats;
@@ -655,6 +655,11 @@ int netvsc_recv_callback(struct net_device *net,
         * interface in the guest.
         */
        rcu_read_lock();
+       net_device = rcu_dereference(net_device_ctx->nvdev);
+       if (unlikely(!net_device))
+               goto drop;
+
+       nvchan = &net_device->chan_table[q_idx];
        vf_netdev = rcu_dereference(net_device_ctx->vf_netdev);
        if (vf_netdev && (vf_netdev->flags & IFF_UP))
                net = vf_netdev;
@@ -663,6 +668,7 @@ int netvsc_recv_callback(struct net_device *net,
        skb = netvsc_alloc_recv_skb(net, &nvchan->napi,
                                    csum_info, vlan, data, len);
        if (unlikely(!skb)) {
+drop:
                ++net->stats.rx_dropped;
                rcu_read_unlock();
                return NVSP_STAT_FAIL;
@@ -704,7 +710,7 @@ static void netvsc_get_channels(struct net_device *net,
                                struct ethtool_channels *channel)
 {
        struct net_device_context *net_device_ctx = netdev_priv(net);
-       struct netvsc_device *nvdev = net_device_ctx->nvdev;
+       struct netvsc_device *nvdev = rtnl_dereference(net_device_ctx->nvdev);
 
        if (nvdev) {
                channel->max_combined   = nvdev->max_chn;
@@ -741,7 +747,7 @@ static int netvsc_set_channels(struct net_device *net,
 {
        struct net_device_context *net_device_ctx = netdev_priv(net);
        struct hv_device *dev = net_device_ctx->device_ctx;
-       struct netvsc_device *nvdev = net_device_ctx->nvdev;
+       struct netvsc_device *nvdev = rtnl_dereference(net_device_ctx->nvdev);
        unsigned int count = channels->combined_count;
        bool was_running;
        int ret;
@@ -848,7 +854,7 @@ static int netvsc_set_link_ksettings(struct net_device *dev,
 static int netvsc_change_mtu(struct net_device *ndev, int mtu)
 {
        struct net_device_context *ndevctx = netdev_priv(ndev);
-       struct netvsc_device *nvdev = ndevctx->nvdev;
+       struct netvsc_device *nvdev = rtnl_dereference(ndevctx->nvdev);
        struct hv_device *hdev = ndevctx->device_ctx;
        struct netvsc_device_info device_info;
        bool was_running;
@@ -897,7 +903,7 @@ static void netvsc_get_stats64(struct net_device *net,
                               struct rtnl_link_stats64 *t)
 {
        struct net_device_context *ndev_ctx = netdev_priv(net);
-       struct netvsc_device *nvdev = ndev_ctx->nvdev;
+       struct netvsc_device *nvdev = rcu_dereference(ndev_ctx->nvdev);
        int i;
 
        if (!nvdev)
@@ -982,7 +988,10 @@ static const struct {
 static int netvsc_get_sset_count(struct net_device *dev, int string_set)
 {
        struct net_device_context *ndc = netdev_priv(dev);
-       struct netvsc_device *nvdev = ndc->nvdev;
+       struct netvsc_device *nvdev = rcu_dereference(ndc->nvdev);
+
+       if (!nvdev)
+               return -ENODEV;
 
        switch (string_set) {
        case ETH_SS_STATS:
@@ -996,13 +1005,16 @@ static void netvsc_get_ethtool_stats(struct net_device *dev,
                                     struct ethtool_stats *stats, u64 *data)
 {
        struct net_device_context *ndc = netdev_priv(dev);
-       struct netvsc_device *nvdev = ndc->nvdev;
+       struct netvsc_device *nvdev = rcu_dereference(ndc->nvdev);
        const void *nds = &ndc->eth_stats;
        const struct netvsc_stats *qstats;
        unsigned int start;
        u64 packets, bytes;
        int i, j;
 
+       if (!nvdev)
+               return;
+
        for (i = 0; i < NETVSC_GLOBAL_STATS_LEN; i++)
                data[i] = *(unsigned long *)(nds + netvsc_stats[i].offset);
 
@@ -1031,10 +1043,13 @@ static void netvsc_get_ethtool_stats(struct net_device *dev,
 static void netvsc_get_strings(struct net_device *dev, u32 stringset, u8 *data)
 {
        struct net_device_context *ndc = netdev_priv(dev);
-       struct netvsc_device *nvdev = ndc->nvdev;
+       struct netvsc_device *nvdev = rcu_dereference(ndc->nvdev);
        u8 *p = data;
        int i;
 
+       if (!nvdev)
+               return;
+
        switch (stringset) {
        case ETH_SS_STATS:
                for (i = 0; i < ARRAY_SIZE(netvsc_stats); i++)
@@ -1086,7 +1101,10 @@ netvsc_get_rxnfc(struct net_device *dev, struct ethtool_rxnfc *info,
                 u32 *rules)
 {
        struct net_device_context *ndc = netdev_priv(dev);
-       struct netvsc_device *nvdev = ndc->nvdev;
+       struct netvsc_device *nvdev = rcu_dereference(ndc->nvdev);
+
+       if (!nvdev)
+               return -ENODEV;
 
        switch (info->cmd) {
        case ETHTOOL_GRXRINGS:
@@ -1122,10 +1140,13 @@ static int netvsc_get_rxfh(struct net_device *dev, u32 *indir, u8 *key,
                           u8 *hfunc)
 {
        struct net_device_context *ndc = netdev_priv(dev);
-       struct netvsc_device *ndev = ndc->nvdev;
+       struct netvsc_device *ndev = rcu_dereference(ndc->nvdev);
        struct rndis_device *rndis_dev = ndev->extension;
        int i;
 
+       if (!ndev)
+               return -ENODEV;
+
        if (hfunc)
                *hfunc = ETH_RSS_HASH_TOP;      /* Toeplitz */
 
@@ -1144,10 +1165,13 @@ static int netvsc_set_rxfh(struct net_device *dev, const u32 *indir,
                           const u8 *key, const u8 hfunc)
 {
        struct net_device_context *ndc = netdev_priv(dev);
-       struct netvsc_device *ndev = ndc->nvdev;
+       struct netvsc_device *ndev = rtnl_dereference(ndc->nvdev);
        struct rndis_device *rndis_dev = ndev->extension;
        int i;
 
+       if (!ndev)
+               return -ENODEV;
+
        if (hfunc != ETH_RSS_HASH_NO_CHANGE && hfunc != ETH_RSS_HASH_TOP)
                return -EOPNOTSUPP;
 
@@ -1224,7 +1248,7 @@ static void netvsc_link_change(struct work_struct *w)
        if (ndev_ctx->start_remove)
                goto out_unlock;
 
-       net_device = ndev_ctx->nvdev;
+       net_device = rtnl_dereference(ndev_ctx->nvdev);
        rdev = net_device->extension;
 
        next_reconfig = ndev_ctx->last_reconfig + LINKCHANGE_INT;
@@ -1365,7 +1389,7 @@ static int netvsc_register_vf(struct net_device *vf_netdev)
                return NOTIFY_DONE;
 
        net_device_ctx = netdev_priv(ndev);
-       netvsc_dev = net_device_ctx->nvdev;
+       netvsc_dev = rtnl_dereference(net_device_ctx->nvdev);
        if (!netvsc_dev || rtnl_dereference(net_device_ctx->vf_netdev))
                return NOTIFY_DONE;
 
@@ -1391,7 +1415,7 @@ static int netvsc_vf_up(struct net_device *vf_netdev)
                return NOTIFY_DONE;
 
        net_device_ctx = netdev_priv(ndev);
-       netvsc_dev = net_device_ctx->nvdev;
+       netvsc_dev = rtnl_dereference(net_device_ctx->nvdev);
 
        netdev_info(ndev, "VF up: %s\n", vf_netdev->name);
 
@@ -1425,7 +1449,7 @@ static int netvsc_vf_down(struct net_device *vf_netdev)
                return NOTIFY_DONE;
 
        net_device_ctx = netdev_priv(ndev);
-       netvsc_dev = net_device_ctx->nvdev;
+       netvsc_dev = rtnl_dereference(net_device_ctx->nvdev);
 
        netdev_info(ndev, "VF down: %s\n", vf_netdev->name);
        netvsc_switch_datapath(ndev, false);
@@ -1519,6 +1543,7 @@ static int netvsc_probe(struct hv_device *dev,
                NETIF_F_HW_VLAN_CTAG_TX | NETIF_F_HW_VLAN_CTAG_RX;
        net->vlan_features = net->features;
 
+       /* RCU not necessary here, device not registered */
        nvdev = net_device_ctx->nvdev;
        netif_set_real_num_tx_queues(net, nvdev->num_chn);
        netif_set_real_num_rx_queues(net, nvdev->num_chn);