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0001 // SPDX-License-Identifier: GPL-2.0-only
0002 #include <linux/etherdevice.h>
0003 #include <linux/if_tap.h>
0004 #include <linux/if_vlan.h>
0005 #include <linux/interrupt.h>
0006 #include <linux/nsproxy.h>
0007 #include <linux/compat.h>
0008 #include <linux/if_tun.h>
0009 #include <linux/module.h>
0010 #include <linux/skbuff.h>
0011 #include <linux/cache.h>
0012 #include <linux/sched/signal.h>
0013 #include <linux/types.h>
0014 #include <linux/slab.h>
0015 #include <linux/wait.h>
0016 #include <linux/cdev.h>
0017 #include <linux/idr.h>
0018 #include <linux/fs.h>
0019 #include <linux/uio.h>
0020 
0021 #include <net/net_namespace.h>
0022 #include <net/rtnetlink.h>
0023 #include <net/sock.h>
0024 #include <linux/virtio_net.h>
0025 #include <linux/skb_array.h>
0026 
0027 #define TAP_IFFEATURES (IFF_VNET_HDR | IFF_MULTI_QUEUE)
0028 
0029 #define TAP_VNET_LE 0x80000000
0030 #define TAP_VNET_BE 0x40000000
0031 
0032 #ifdef CONFIG_TUN_VNET_CROSS_LE
0033 static inline bool tap_legacy_is_little_endian(struct tap_queue *q)
0034 {
0035     return q->flags & TAP_VNET_BE ? false :
0036         virtio_legacy_is_little_endian();
0037 }
0038 
0039 static long tap_get_vnet_be(struct tap_queue *q, int __user *sp)
0040 {
0041     int s = !!(q->flags & TAP_VNET_BE);
0042 
0043     if (put_user(s, sp))
0044         return -EFAULT;
0045 
0046     return 0;
0047 }
0048 
0049 static long tap_set_vnet_be(struct tap_queue *q, int __user *sp)
0050 {
0051     int s;
0052 
0053     if (get_user(s, sp))
0054         return -EFAULT;
0055 
0056     if (s)
0057         q->flags |= TAP_VNET_BE;
0058     else
0059         q->flags &= ~TAP_VNET_BE;
0060 
0061     return 0;
0062 }
0063 #else
0064 static inline bool tap_legacy_is_little_endian(struct tap_queue *q)
0065 {
0066     return virtio_legacy_is_little_endian();
0067 }
0068 
0069 static long tap_get_vnet_be(struct tap_queue *q, int __user *argp)
0070 {
0071     return -EINVAL;
0072 }
0073 
0074 static long tap_set_vnet_be(struct tap_queue *q, int __user *argp)
0075 {
0076     return -EINVAL;
0077 }
0078 #endif /* CONFIG_TUN_VNET_CROSS_LE */
0079 
0080 static inline bool tap_is_little_endian(struct tap_queue *q)
0081 {
0082     return q->flags & TAP_VNET_LE ||
0083         tap_legacy_is_little_endian(q);
0084 }
0085 
0086 static inline u16 tap16_to_cpu(struct tap_queue *q, __virtio16 val)
0087 {
0088     return __virtio16_to_cpu(tap_is_little_endian(q), val);
0089 }
0090 
0091 static inline __virtio16 cpu_to_tap16(struct tap_queue *q, u16 val)
0092 {
0093     return __cpu_to_virtio16(tap_is_little_endian(q), val);
0094 }
0095 
0096 static struct proto tap_proto = {
0097     .name = "tap",
0098     .owner = THIS_MODULE,
0099     .obj_size = sizeof(struct tap_queue),
0100 };
0101 
0102 #define TAP_NUM_DEVS (1U << MINORBITS)
0103 
0104 static LIST_HEAD(major_list);
0105 
0106 struct major_info {
0107     struct rcu_head rcu;
0108     dev_t major;
0109     struct idr minor_idr;
0110     spinlock_t minor_lock;
0111     const char *device_name;
0112     struct list_head next;
0113 };
0114 
0115 #define GOODCOPY_LEN 128
0116 
0117 static const struct proto_ops tap_socket_ops;
0118 
0119 #define RX_OFFLOADS (NETIF_F_GRO | NETIF_F_LRO)
0120 #define TAP_FEATURES (NETIF_F_GSO | NETIF_F_SG | NETIF_F_FRAGLIST)
0121 
0122 static struct tap_dev *tap_dev_get_rcu(const struct net_device *dev)
0123 {
0124     return rcu_dereference(dev->rx_handler_data);
0125 }
0126 
0127 /*
0128  * RCU usage:
0129  * The tap_queue and the macvlan_dev are loosely coupled, the
0130  * pointers from one to the other can only be read while rcu_read_lock
0131  * or rtnl is held.
0132  *
0133  * Both the file and the macvlan_dev hold a reference on the tap_queue
0134  * through sock_hold(&q->sk). When the macvlan_dev goes away first,
0135  * q->vlan becomes inaccessible. When the files gets closed,
0136  * tap_get_queue() fails.
0137  *
0138  * There may still be references to the struct sock inside of the
0139  * queue from outbound SKBs, but these never reference back to the
0140  * file or the dev. The data structure is freed through __sk_free
0141  * when both our references and any pending SKBs are gone.
0142  */
0143 
0144 static int tap_enable_queue(struct tap_dev *tap, struct file *file,
0145                 struct tap_queue *q)
0146 {
0147     int err = -EINVAL;
0148 
0149     ASSERT_RTNL();
0150 
0151     if (q->enabled)
0152         goto out;
0153 
0154     err = 0;
0155     rcu_assign_pointer(tap->taps[tap->numvtaps], q);
0156     q->queue_index = tap->numvtaps;
0157     q->enabled = true;
0158 
0159     tap->numvtaps++;
0160 out:
0161     return err;
0162 }
0163 
0164 /* Requires RTNL */
0165 static int tap_set_queue(struct tap_dev *tap, struct file *file,
0166              struct tap_queue *q)
0167 {
0168     if (tap->numqueues == MAX_TAP_QUEUES)
0169         return -EBUSY;
0170 
0171     rcu_assign_pointer(q->tap, tap);
0172     rcu_assign_pointer(tap->taps[tap->numvtaps], q);
0173     sock_hold(&q->sk);
0174 
0175     q->file = file;
0176     q->queue_index = tap->numvtaps;
0177     q->enabled = true;
0178     file->private_data = q;
0179     list_add_tail(&q->next, &tap->queue_list);
0180 
0181     tap->numvtaps++;
0182     tap->numqueues++;
0183 
0184     return 0;
0185 }
0186 
0187 static int tap_disable_queue(struct tap_queue *q)
0188 {
0189     struct tap_dev *tap;
0190     struct tap_queue *nq;
0191 
0192     ASSERT_RTNL();
0193     if (!q->enabled)
0194         return -EINVAL;
0195 
0196     tap = rtnl_dereference(q->tap);
0197 
0198     if (tap) {
0199         int index = q->queue_index;
0200         BUG_ON(index >= tap->numvtaps);
0201         nq = rtnl_dereference(tap->taps[tap->numvtaps - 1]);
0202         nq->queue_index = index;
0203 
0204         rcu_assign_pointer(tap->taps[index], nq);
0205         RCU_INIT_POINTER(tap->taps[tap->numvtaps - 1], NULL);
0206         q->enabled = false;
0207 
0208         tap->numvtaps--;
0209     }
0210 
0211     return 0;
0212 }
0213 
0214 /*
0215  * The file owning the queue got closed, give up both
0216  * the reference that the files holds as well as the
0217  * one from the macvlan_dev if that still exists.
0218  *
0219  * Using the spinlock makes sure that we don't get
0220  * to the queue again after destroying it.
0221  */
0222 static void tap_put_queue(struct tap_queue *q)
0223 {
0224     struct tap_dev *tap;
0225 
0226     rtnl_lock();
0227     tap = rtnl_dereference(q->tap);
0228 
0229     if (tap) {
0230         if (q->enabled)
0231             BUG_ON(tap_disable_queue(q));
0232 
0233         tap->numqueues--;
0234         RCU_INIT_POINTER(q->tap, NULL);
0235         sock_put(&q->sk);
0236         list_del_init(&q->next);
0237     }
0238 
0239     rtnl_unlock();
0240 
0241     synchronize_rcu();
0242     sock_put(&q->sk);
0243 }
0244 
0245 /*
0246  * Select a queue based on the rxq of the device on which this packet
0247  * arrived. If the incoming device is not mq, calculate a flow hash
0248  * to select a queue. If all fails, find the first available queue.
0249  * Cache vlan->numvtaps since it can become zero during the execution
0250  * of this function.
0251  */
0252 static struct tap_queue *tap_get_queue(struct tap_dev *tap,
0253                        struct sk_buff *skb)
0254 {
0255     struct tap_queue *queue = NULL;
0256     /* Access to taps array is protected by rcu, but access to numvtaps
0257      * isn't. Below we use it to lookup a queue, but treat it as a hint
0258      * and validate that the result isn't NULL - in case we are
0259      * racing against queue removal.
0260      */
0261     int numvtaps = READ_ONCE(tap->numvtaps);
0262     __u32 rxq;
0263 
0264     if (!numvtaps)
0265         goto out;
0266 
0267     if (numvtaps == 1)
0268         goto single;
0269 
0270     /* Check if we can use flow to select a queue */
0271     rxq = skb_get_hash(skb);
0272     if (rxq) {
0273         queue = rcu_dereference(tap->taps[rxq % numvtaps]);
0274         goto out;
0275     }
0276 
0277     if (likely(skb_rx_queue_recorded(skb))) {
0278         rxq = skb_get_rx_queue(skb);
0279 
0280         while (unlikely(rxq >= numvtaps))
0281             rxq -= numvtaps;
0282 
0283         queue = rcu_dereference(tap->taps[rxq]);
0284         goto out;
0285     }
0286 
0287 single:
0288     queue = rcu_dereference(tap->taps[0]);
0289 out:
0290     return queue;
0291 }
0292 
0293 /*
0294  * The net_device is going away, give up the reference
0295  * that it holds on all queues and safely set the pointer
0296  * from the queues to NULL.
0297  */
0298 void tap_del_queues(struct tap_dev *tap)
0299 {
0300     struct tap_queue *q, *tmp;
0301 
0302     ASSERT_RTNL();
0303     list_for_each_entry_safe(q, tmp, &tap->queue_list, next) {
0304         list_del_init(&q->next);
0305         RCU_INIT_POINTER(q->tap, NULL);
0306         if (q->enabled)
0307             tap->numvtaps--;
0308         tap->numqueues--;
0309         sock_put(&q->sk);
0310     }
0311     BUG_ON(tap->numvtaps);
0312     BUG_ON(tap->numqueues);
0313     /* guarantee that any future tap_set_queue will fail */
0314     tap->numvtaps = MAX_TAP_QUEUES;
0315 }
0316 EXPORT_SYMBOL_GPL(tap_del_queues);
0317 
0318 rx_handler_result_t tap_handle_frame(struct sk_buff **pskb)
0319 {
0320     struct sk_buff *skb = *pskb;
0321     struct net_device *dev = skb->dev;
0322     struct tap_dev *tap;
0323     struct tap_queue *q;
0324     netdev_features_t features = TAP_FEATURES;
0325     enum skb_drop_reason drop_reason;
0326 
0327     tap = tap_dev_get_rcu(dev);
0328     if (!tap)
0329         return RX_HANDLER_PASS;
0330 
0331     q = tap_get_queue(tap, skb);
0332     if (!q)
0333         return RX_HANDLER_PASS;
0334 
0335     skb_push(skb, ETH_HLEN);
0336 
0337     /* Apply the forward feature mask so that we perform segmentation
0338      * according to users wishes.  This only works if VNET_HDR is
0339      * enabled.
0340      */
0341     if (q->flags & IFF_VNET_HDR)
0342         features |= tap->tap_features;
0343     if (netif_needs_gso(skb, features)) {
0344         struct sk_buff *segs = __skb_gso_segment(skb, features, false);
0345         struct sk_buff *next;
0346 
0347         if (IS_ERR(segs)) {
0348             drop_reason = SKB_DROP_REASON_SKB_GSO_SEG;
0349             goto drop;
0350         }
0351 
0352         if (!segs) {
0353             if (ptr_ring_produce(&q->ring, skb)) {
0354                 drop_reason = SKB_DROP_REASON_FULL_RING;
0355                 goto drop;
0356             }
0357             goto wake_up;
0358         }
0359 
0360         consume_skb(skb);
0361         skb_list_walk_safe(segs, skb, next) {
0362             skb_mark_not_on_list(skb);
0363             if (ptr_ring_produce(&q->ring, skb)) {
0364                 drop_reason = SKB_DROP_REASON_FULL_RING;
0365                 kfree_skb_reason(skb, drop_reason);
0366                 kfree_skb_list_reason(next, drop_reason);
0367                 break;
0368             }
0369         }
0370     } else {
0371         /* If we receive a partial checksum and the tap side
0372          * doesn't support checksum offload, compute the checksum.
0373          * Note: it doesn't matter which checksum feature to
0374          *    check, we either support them all or none.
0375          */
0376         if (skb->ip_summed == CHECKSUM_PARTIAL &&
0377             !(features & NETIF_F_CSUM_MASK) &&
0378             skb_checksum_help(skb)) {
0379             drop_reason = SKB_DROP_REASON_SKB_CSUM;
0380             goto drop;
0381         }
0382         if (ptr_ring_produce(&q->ring, skb)) {
0383             drop_reason = SKB_DROP_REASON_FULL_RING;
0384             goto drop;
0385         }
0386     }
0387 
0388 wake_up:
0389     wake_up_interruptible_poll(sk_sleep(&q->sk), EPOLLIN | EPOLLRDNORM | EPOLLRDBAND);
0390     return RX_HANDLER_CONSUMED;
0391 
0392 drop:
0393     /* Count errors/drops only here, thus don't care about args. */
0394     if (tap->count_rx_dropped)
0395         tap->count_rx_dropped(tap);
0396     kfree_skb_reason(skb, drop_reason);
0397     return RX_HANDLER_CONSUMED;
0398 }
0399 EXPORT_SYMBOL_GPL(tap_handle_frame);
0400 
0401 static struct major_info *tap_get_major(int major)
0402 {
0403     struct major_info *tap_major;
0404 
0405     list_for_each_entry_rcu(tap_major, &major_list, next) {
0406         if (tap_major->major == major)
0407             return tap_major;
0408     }
0409 
0410     return NULL;
0411 }
0412 
0413 int tap_get_minor(dev_t major, struct tap_dev *tap)
0414 {
0415     int retval = -ENOMEM;
0416     struct major_info *tap_major;
0417 
0418     rcu_read_lock();
0419     tap_major = tap_get_major(MAJOR(major));
0420     if (!tap_major) {
0421         retval = -EINVAL;
0422         goto unlock;
0423     }
0424 
0425     spin_lock(&tap_major->minor_lock);
0426     retval = idr_alloc(&tap_major->minor_idr, tap, 1, TAP_NUM_DEVS, GFP_ATOMIC);
0427     if (retval >= 0) {
0428         tap->minor = retval;
0429     } else if (retval == -ENOSPC) {
0430         netdev_err(tap->dev, "Too many tap devices\n");
0431         retval = -EINVAL;
0432     }
0433     spin_unlock(&tap_major->minor_lock);
0434 
0435 unlock:
0436     rcu_read_unlock();
0437     return retval < 0 ? retval : 0;
0438 }
0439 EXPORT_SYMBOL_GPL(tap_get_minor);
0440 
0441 void tap_free_minor(dev_t major, struct tap_dev *tap)
0442 {
0443     struct major_info *tap_major;
0444 
0445     rcu_read_lock();
0446     tap_major = tap_get_major(MAJOR(major));
0447     if (!tap_major) {
0448         goto unlock;
0449     }
0450 
0451     spin_lock(&tap_major->minor_lock);
0452     if (tap->minor) {
0453         idr_remove(&tap_major->minor_idr, tap->minor);
0454         tap->minor = 0;
0455     }
0456     spin_unlock(&tap_major->minor_lock);
0457 
0458 unlock:
0459     rcu_read_unlock();
0460 }
0461 EXPORT_SYMBOL_GPL(tap_free_minor);
0462 
0463 static struct tap_dev *dev_get_by_tap_file(int major, int minor)
0464 {
0465     struct net_device *dev = NULL;
0466     struct tap_dev *tap;
0467     struct major_info *tap_major;
0468 
0469     rcu_read_lock();
0470     tap_major = tap_get_major(major);
0471     if (!tap_major) {
0472         tap = NULL;
0473         goto unlock;
0474     }
0475 
0476     spin_lock(&tap_major->minor_lock);
0477     tap = idr_find(&tap_major->minor_idr, minor);
0478     if (tap) {
0479         dev = tap->dev;
0480         dev_hold(dev);
0481     }
0482     spin_unlock(&tap_major->minor_lock);
0483 
0484 unlock:
0485     rcu_read_unlock();
0486     return tap;
0487 }
0488 
0489 static void tap_sock_write_space(struct sock *sk)
0490 {
0491     wait_queue_head_t *wqueue;
0492 
0493     if (!sock_writeable(sk) ||
0494         !test_and_clear_bit(SOCKWQ_ASYNC_NOSPACE, &sk->sk_socket->flags))
0495         return;
0496 
0497     wqueue = sk_sleep(sk);
0498     if (wqueue && waitqueue_active(wqueue))
0499         wake_up_interruptible_poll(wqueue, EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND);
0500 }
0501 
0502 static void tap_sock_destruct(struct sock *sk)
0503 {
0504     struct tap_queue *q = container_of(sk, struct tap_queue, sk);
0505 
0506     ptr_ring_cleanup(&q->ring, __skb_array_destroy_skb);
0507 }
0508 
0509 static int tap_open(struct inode *inode, struct file *file)
0510 {
0511     struct net *net = current->nsproxy->net_ns;
0512     struct tap_dev *tap;
0513     struct tap_queue *q;
0514     int err = -ENODEV;
0515 
0516     rtnl_lock();
0517     tap = dev_get_by_tap_file(imajor(inode), iminor(inode));
0518     if (!tap)
0519         goto err;
0520 
0521     err = -ENOMEM;
0522     q = (struct tap_queue *)sk_alloc(net, AF_UNSPEC, GFP_KERNEL,
0523                          &tap_proto, 0);
0524     if (!q)
0525         goto err;
0526     if (ptr_ring_init(&q->ring, tap->dev->tx_queue_len, GFP_KERNEL)) {
0527         sk_free(&q->sk);
0528         goto err;
0529     }
0530 
0531     init_waitqueue_head(&q->sock.wq.wait);
0532     q->sock.type = SOCK_RAW;
0533     q->sock.state = SS_CONNECTED;
0534     q->sock.file = file;
0535     q->sock.ops = &tap_socket_ops;
0536     sock_init_data(&q->sock, &q->sk);
0537     q->sk.sk_write_space = tap_sock_write_space;
0538     q->sk.sk_destruct = tap_sock_destruct;
0539     q->flags = IFF_VNET_HDR | IFF_NO_PI | IFF_TAP;
0540     q->vnet_hdr_sz = sizeof(struct virtio_net_hdr);
0541 
0542     /*
0543      * so far only KVM virtio_net uses tap, enable zero copy between
0544      * guest kernel and host kernel when lower device supports zerocopy
0545      *
0546      * The macvlan supports zerocopy iff the lower device supports zero
0547      * copy so we don't have to look at the lower device directly.
0548      */
0549     if ((tap->dev->features & NETIF_F_HIGHDMA) && (tap->dev->features & NETIF_F_SG))
0550         sock_set_flag(&q->sk, SOCK_ZEROCOPY);
0551 
0552     err = tap_set_queue(tap, file, q);
0553     if (err) {
0554         /* tap_sock_destruct() will take care of freeing ptr_ring */
0555         goto err_put;
0556     }
0557 
0558     dev_put(tap->dev);
0559 
0560     rtnl_unlock();
0561     return err;
0562 
0563 err_put:
0564     sock_put(&q->sk);
0565 err:
0566     if (tap)
0567         dev_put(tap->dev);
0568 
0569     rtnl_unlock();
0570     return err;
0571 }
0572 
0573 static int tap_release(struct inode *inode, struct file *file)
0574 {
0575     struct tap_queue *q = file->private_data;
0576     tap_put_queue(q);
0577     return 0;
0578 }
0579 
0580 static __poll_t tap_poll(struct file *file, poll_table *wait)
0581 {
0582     struct tap_queue *q = file->private_data;
0583     __poll_t mask = EPOLLERR;
0584 
0585     if (!q)
0586         goto out;
0587 
0588     mask = 0;
0589     poll_wait(file, &q->sock.wq.wait, wait);
0590 
0591     if (!ptr_ring_empty(&q->ring))
0592         mask |= EPOLLIN | EPOLLRDNORM;
0593 
0594     if (sock_writeable(&q->sk) ||
0595         (!test_and_set_bit(SOCKWQ_ASYNC_NOSPACE, &q->sock.flags) &&
0596          sock_writeable(&q->sk)))
0597         mask |= EPOLLOUT | EPOLLWRNORM;
0598 
0599 out:
0600     return mask;
0601 }
0602 
0603 static inline struct sk_buff *tap_alloc_skb(struct sock *sk, size_t prepad,
0604                         size_t len, size_t linear,
0605                         int noblock, int *err)
0606 {
0607     struct sk_buff *skb;
0608 
0609     /* Under a page?  Don't bother with paged skb. */
0610     if (prepad + len < PAGE_SIZE || !linear)
0611         linear = len;
0612 
0613     skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,
0614                    err, 0);
0615     if (!skb)
0616         return NULL;
0617 
0618     skb_reserve(skb, prepad);
0619     skb_put(skb, linear);
0620     skb->data_len = len - linear;
0621     skb->len += len - linear;
0622 
0623     return skb;
0624 }
0625 
0626 /* Neighbour code has some assumptions on HH_DATA_MOD alignment */
0627 #define TAP_RESERVE HH_DATA_OFF(ETH_HLEN)
0628 
0629 /* Get packet from user space buffer */
0630 static ssize_t tap_get_user(struct tap_queue *q, void *msg_control,
0631                 struct iov_iter *from, int noblock)
0632 {
0633     int good_linear = SKB_MAX_HEAD(TAP_RESERVE);
0634     struct sk_buff *skb;
0635     struct tap_dev *tap;
0636     unsigned long total_len = iov_iter_count(from);
0637     unsigned long len = total_len;
0638     int err;
0639     struct virtio_net_hdr vnet_hdr = { 0 };
0640     int vnet_hdr_len = 0;
0641     int copylen = 0;
0642     int depth;
0643     bool zerocopy = false;
0644     size_t linear;
0645     enum skb_drop_reason drop_reason;
0646 
0647     if (q->flags & IFF_VNET_HDR) {
0648         vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
0649 
0650         err = -EINVAL;
0651         if (len < vnet_hdr_len)
0652             goto err;
0653         len -= vnet_hdr_len;
0654 
0655         err = -EFAULT;
0656         if (!copy_from_iter_full(&vnet_hdr, sizeof(vnet_hdr), from))
0657             goto err;
0658         iov_iter_advance(from, vnet_hdr_len - sizeof(vnet_hdr));
0659         if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
0660              tap16_to_cpu(q, vnet_hdr.csum_start) +
0661              tap16_to_cpu(q, vnet_hdr.csum_offset) + 2 >
0662                  tap16_to_cpu(q, vnet_hdr.hdr_len))
0663             vnet_hdr.hdr_len = cpu_to_tap16(q,
0664                  tap16_to_cpu(q, vnet_hdr.csum_start) +
0665                  tap16_to_cpu(q, vnet_hdr.csum_offset) + 2);
0666         err = -EINVAL;
0667         if (tap16_to_cpu(q, vnet_hdr.hdr_len) > len)
0668             goto err;
0669     }
0670 
0671     err = -EINVAL;
0672     if (unlikely(len < ETH_HLEN))
0673         goto err;
0674 
0675     if (msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) {
0676         struct iov_iter i;
0677 
0678         copylen = vnet_hdr.hdr_len ?
0679             tap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN;
0680         if (copylen > good_linear)
0681             copylen = good_linear;
0682         else if (copylen < ETH_HLEN)
0683             copylen = ETH_HLEN;
0684         linear = copylen;
0685         i = *from;
0686         iov_iter_advance(&i, copylen);
0687         if (iov_iter_npages(&i, INT_MAX) <= MAX_SKB_FRAGS)
0688             zerocopy = true;
0689     }
0690 
0691     if (!zerocopy) {
0692         copylen = len;
0693         linear = tap16_to_cpu(q, vnet_hdr.hdr_len);
0694         if (linear > good_linear)
0695             linear = good_linear;
0696         else if (linear < ETH_HLEN)
0697             linear = ETH_HLEN;
0698     }
0699 
0700     skb = tap_alloc_skb(&q->sk, TAP_RESERVE, copylen,
0701                 linear, noblock, &err);
0702     if (!skb)
0703         goto err;
0704 
0705     if (zerocopy)
0706         err = zerocopy_sg_from_iter(skb, from);
0707     else
0708         err = skb_copy_datagram_from_iter(skb, 0, from, len);
0709 
0710     if (err) {
0711         drop_reason = SKB_DROP_REASON_SKB_UCOPY_FAULT;
0712         goto err_kfree;
0713     }
0714 
0715     skb_set_network_header(skb, ETH_HLEN);
0716     skb_reset_mac_header(skb);
0717     skb->protocol = eth_hdr(skb)->h_proto;
0718 
0719     rcu_read_lock();
0720     tap = rcu_dereference(q->tap);
0721     if (!tap) {
0722         kfree_skb(skb);
0723         rcu_read_unlock();
0724         return total_len;
0725     }
0726     skb->dev = tap->dev;
0727 
0728     if (vnet_hdr_len) {
0729         err = virtio_net_hdr_to_skb(skb, &vnet_hdr,
0730                         tap_is_little_endian(q));
0731         if (err) {
0732             rcu_read_unlock();
0733             drop_reason = SKB_DROP_REASON_DEV_HDR;
0734             goto err_kfree;
0735         }
0736     }
0737 
0738     skb_probe_transport_header(skb);
0739 
0740     /* Move network header to the right position for VLAN tagged packets */
0741     if (eth_type_vlan(skb->protocol) &&
0742         __vlan_get_protocol(skb, skb->protocol, &depth) != 0)
0743         skb_set_network_header(skb, depth);
0744 
0745     /* copy skb_ubuf_info for callback when skb has no error */
0746     if (zerocopy) {
0747         skb_zcopy_init(skb, msg_control);
0748     } else if (msg_control) {
0749         struct ubuf_info *uarg = msg_control;
0750         uarg->callback(NULL, uarg, false);
0751     }
0752 
0753     dev_queue_xmit(skb);
0754     rcu_read_unlock();
0755     return total_len;
0756 
0757 err_kfree:
0758     kfree_skb_reason(skb, drop_reason);
0759 
0760 err:
0761     rcu_read_lock();
0762     tap = rcu_dereference(q->tap);
0763     if (tap && tap->count_tx_dropped)
0764         tap->count_tx_dropped(tap);
0765     rcu_read_unlock();
0766 
0767     return err;
0768 }
0769 
0770 static ssize_t tap_write_iter(struct kiocb *iocb, struct iov_iter *from)
0771 {
0772     struct file *file = iocb->ki_filp;
0773     struct tap_queue *q = file->private_data;
0774 
0775     return tap_get_user(q, NULL, from, file->f_flags & O_NONBLOCK);
0776 }
0777 
0778 /* Put packet to the user space buffer */
0779 static ssize_t tap_put_user(struct tap_queue *q,
0780                 const struct sk_buff *skb,
0781                 struct iov_iter *iter)
0782 {
0783     int ret;
0784     int vnet_hdr_len = 0;
0785     int vlan_offset = 0;
0786     int total;
0787 
0788     if (q->flags & IFF_VNET_HDR) {
0789         int vlan_hlen = skb_vlan_tag_present(skb) ? VLAN_HLEN : 0;
0790         struct virtio_net_hdr vnet_hdr;
0791 
0792         vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
0793         if (iov_iter_count(iter) < vnet_hdr_len)
0794             return -EINVAL;
0795 
0796         if (virtio_net_hdr_from_skb(skb, &vnet_hdr,
0797                         tap_is_little_endian(q), true,
0798                         vlan_hlen))
0799             BUG();
0800 
0801         if (copy_to_iter(&vnet_hdr, sizeof(vnet_hdr), iter) !=
0802             sizeof(vnet_hdr))
0803             return -EFAULT;
0804 
0805         iov_iter_advance(iter, vnet_hdr_len - sizeof(vnet_hdr));
0806     }
0807     total = vnet_hdr_len;
0808     total += skb->len;
0809 
0810     if (skb_vlan_tag_present(skb)) {
0811         struct {
0812             __be16 h_vlan_proto;
0813             __be16 h_vlan_TCI;
0814         } veth;
0815         veth.h_vlan_proto = skb->vlan_proto;
0816         veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
0817 
0818         vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);
0819         total += VLAN_HLEN;
0820 
0821         ret = skb_copy_datagram_iter(skb, 0, iter, vlan_offset);
0822         if (ret || !iov_iter_count(iter))
0823             goto done;
0824 
0825         ret = copy_to_iter(&veth, sizeof(veth), iter);
0826         if (ret != sizeof(veth) || !iov_iter_count(iter))
0827             goto done;
0828     }
0829 
0830     ret = skb_copy_datagram_iter(skb, vlan_offset, iter,
0831                      skb->len - vlan_offset);
0832 
0833 done:
0834     return ret ? ret : total;
0835 }
0836 
0837 static ssize_t tap_do_read(struct tap_queue *q,
0838                struct iov_iter *to,
0839                int noblock, struct sk_buff *skb)
0840 {
0841     DEFINE_WAIT(wait);
0842     ssize_t ret = 0;
0843 
0844     if (!iov_iter_count(to)) {
0845         kfree_skb(skb);
0846         return 0;
0847     }
0848 
0849     if (skb)
0850         goto put;
0851 
0852     while (1) {
0853         if (!noblock)
0854             prepare_to_wait(sk_sleep(&q->sk), &wait,
0855                     TASK_INTERRUPTIBLE);
0856 
0857         /* Read frames from the queue */
0858         skb = ptr_ring_consume(&q->ring);
0859         if (skb)
0860             break;
0861         if (noblock) {
0862             ret = -EAGAIN;
0863             break;
0864         }
0865         if (signal_pending(current)) {
0866             ret = -ERESTARTSYS;
0867             break;
0868         }
0869         /* Nothing to read, let's sleep */
0870         schedule();
0871     }
0872     if (!noblock)
0873         finish_wait(sk_sleep(&q->sk), &wait);
0874 
0875 put:
0876     if (skb) {
0877         ret = tap_put_user(q, skb, to);
0878         if (unlikely(ret < 0))
0879             kfree_skb(skb);
0880         else
0881             consume_skb(skb);
0882     }
0883     return ret;
0884 }
0885 
0886 static ssize_t tap_read_iter(struct kiocb *iocb, struct iov_iter *to)
0887 {
0888     struct file *file = iocb->ki_filp;
0889     struct tap_queue *q = file->private_data;
0890     ssize_t len = iov_iter_count(to), ret;
0891 
0892     ret = tap_do_read(q, to, file->f_flags & O_NONBLOCK, NULL);
0893     ret = min_t(ssize_t, ret, len);
0894     if (ret > 0)
0895         iocb->ki_pos = ret;
0896     return ret;
0897 }
0898 
0899 static struct tap_dev *tap_get_tap_dev(struct tap_queue *q)
0900 {
0901     struct tap_dev *tap;
0902 
0903     ASSERT_RTNL();
0904     tap = rtnl_dereference(q->tap);
0905     if (tap)
0906         dev_hold(tap->dev);
0907 
0908     return tap;
0909 }
0910 
0911 static void tap_put_tap_dev(struct tap_dev *tap)
0912 {
0913     dev_put(tap->dev);
0914 }
0915 
0916 static int tap_ioctl_set_queue(struct file *file, unsigned int flags)
0917 {
0918     struct tap_queue *q = file->private_data;
0919     struct tap_dev *tap;
0920     int ret;
0921 
0922     tap = tap_get_tap_dev(q);
0923     if (!tap)
0924         return -EINVAL;
0925 
0926     if (flags & IFF_ATTACH_QUEUE)
0927         ret = tap_enable_queue(tap, file, q);
0928     else if (flags & IFF_DETACH_QUEUE)
0929         ret = tap_disable_queue(q);
0930     else
0931         ret = -EINVAL;
0932 
0933     tap_put_tap_dev(tap);
0934     return ret;
0935 }
0936 
0937 static int set_offload(struct tap_queue *q, unsigned long arg)
0938 {
0939     struct tap_dev *tap;
0940     netdev_features_t features;
0941     netdev_features_t feature_mask = 0;
0942 
0943     tap = rtnl_dereference(q->tap);
0944     if (!tap)
0945         return -ENOLINK;
0946 
0947     features = tap->dev->features;
0948 
0949     if (arg & TUN_F_CSUM) {
0950         feature_mask = NETIF_F_HW_CSUM;
0951 
0952         if (arg & (TUN_F_TSO4 | TUN_F_TSO6)) {
0953             if (arg & TUN_F_TSO_ECN)
0954                 feature_mask |= NETIF_F_TSO_ECN;
0955             if (arg & TUN_F_TSO4)
0956                 feature_mask |= NETIF_F_TSO;
0957             if (arg & TUN_F_TSO6)
0958                 feature_mask |= NETIF_F_TSO6;
0959         }
0960     }
0961 
0962     /* tun/tap driver inverts the usage for TSO offloads, where
0963      * setting the TSO bit means that the userspace wants to
0964      * accept TSO frames and turning it off means that user space
0965      * does not support TSO.
0966      * For tap, we have to invert it to mean the same thing.
0967      * When user space turns off TSO, we turn off GSO/LRO so that
0968      * user-space will not receive TSO frames.
0969      */
0970     if (feature_mask & (NETIF_F_TSO | NETIF_F_TSO6))
0971         features |= RX_OFFLOADS;
0972     else
0973         features &= ~RX_OFFLOADS;
0974 
0975     /* tap_features are the same as features on tun/tap and
0976      * reflect user expectations.
0977      */
0978     tap->tap_features = feature_mask;
0979     if (tap->update_features)
0980         tap->update_features(tap, features);
0981 
0982     return 0;
0983 }
0984 
0985 /*
0986  * provide compatibility with generic tun/tap interface
0987  */
0988 static long tap_ioctl(struct file *file, unsigned int cmd,
0989               unsigned long arg)
0990 {
0991     struct tap_queue *q = file->private_data;
0992     struct tap_dev *tap;
0993     void __user *argp = (void __user *)arg;
0994     struct ifreq __user *ifr = argp;
0995     unsigned int __user *up = argp;
0996     unsigned short u;
0997     int __user *sp = argp;
0998     struct sockaddr sa;
0999     int s;
1000     int ret;
1001 
1002     switch (cmd) {
1003     case TUNSETIFF:
1004         /* ignore the name, just look at flags */
1005         if (get_user(u, &ifr->ifr_flags))
1006             return -EFAULT;
1007 
1008         ret = 0;
1009         if ((u & ~TAP_IFFEATURES) != (IFF_NO_PI | IFF_TAP))
1010             ret = -EINVAL;
1011         else
1012             q->flags = (q->flags & ~TAP_IFFEATURES) | u;
1013 
1014         return ret;
1015 
1016     case TUNGETIFF:
1017         rtnl_lock();
1018         tap = tap_get_tap_dev(q);
1019         if (!tap) {
1020             rtnl_unlock();
1021             return -ENOLINK;
1022         }
1023 
1024         ret = 0;
1025         u = q->flags;
1026         if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) ||
1027             put_user(u, &ifr->ifr_flags))
1028             ret = -EFAULT;
1029         tap_put_tap_dev(tap);
1030         rtnl_unlock();
1031         return ret;
1032 
1033     case TUNSETQUEUE:
1034         if (get_user(u, &ifr->ifr_flags))
1035             return -EFAULT;
1036         rtnl_lock();
1037         ret = tap_ioctl_set_queue(file, u);
1038         rtnl_unlock();
1039         return ret;
1040 
1041     case TUNGETFEATURES:
1042         if (put_user(IFF_TAP | IFF_NO_PI | TAP_IFFEATURES, up))
1043             return -EFAULT;
1044         return 0;
1045 
1046     case TUNSETSNDBUF:
1047         if (get_user(s, sp))
1048             return -EFAULT;
1049         if (s <= 0)
1050             return -EINVAL;
1051 
1052         q->sk.sk_sndbuf = s;
1053         return 0;
1054 
1055     case TUNGETVNETHDRSZ:
1056         s = q->vnet_hdr_sz;
1057         if (put_user(s, sp))
1058             return -EFAULT;
1059         return 0;
1060 
1061     case TUNSETVNETHDRSZ:
1062         if (get_user(s, sp))
1063             return -EFAULT;
1064         if (s < (int)sizeof(struct virtio_net_hdr))
1065             return -EINVAL;
1066 
1067         q->vnet_hdr_sz = s;
1068         return 0;
1069 
1070     case TUNGETVNETLE:
1071         s = !!(q->flags & TAP_VNET_LE);
1072         if (put_user(s, sp))
1073             return -EFAULT;
1074         return 0;
1075 
1076     case TUNSETVNETLE:
1077         if (get_user(s, sp))
1078             return -EFAULT;
1079         if (s)
1080             q->flags |= TAP_VNET_LE;
1081         else
1082             q->flags &= ~TAP_VNET_LE;
1083         return 0;
1084 
1085     case TUNGETVNETBE:
1086         return tap_get_vnet_be(q, sp);
1087 
1088     case TUNSETVNETBE:
1089         return tap_set_vnet_be(q, sp);
1090 
1091     case TUNSETOFFLOAD:
1092         /* let the user check for future flags */
1093         if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
1094                 TUN_F_TSO_ECN | TUN_F_UFO))
1095             return -EINVAL;
1096 
1097         rtnl_lock();
1098         ret = set_offload(q, arg);
1099         rtnl_unlock();
1100         return ret;
1101 
1102     case SIOCGIFHWADDR:
1103         rtnl_lock();
1104         tap = tap_get_tap_dev(q);
1105         if (!tap) {
1106             rtnl_unlock();
1107             return -ENOLINK;
1108         }
1109         ret = 0;
1110         dev_get_mac_address(&sa, dev_net(tap->dev), tap->dev->name);
1111         if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) ||
1112             copy_to_user(&ifr->ifr_hwaddr, &sa, sizeof(sa)))
1113             ret = -EFAULT;
1114         tap_put_tap_dev(tap);
1115         rtnl_unlock();
1116         return ret;
1117 
1118     case SIOCSIFHWADDR:
1119         if (copy_from_user(&sa, &ifr->ifr_hwaddr, sizeof(sa)))
1120             return -EFAULT;
1121         rtnl_lock();
1122         tap = tap_get_tap_dev(q);
1123         if (!tap) {
1124             rtnl_unlock();
1125             return -ENOLINK;
1126         }
1127         ret = dev_set_mac_address_user(tap->dev, &sa, NULL);
1128         tap_put_tap_dev(tap);
1129         rtnl_unlock();
1130         return ret;
1131 
1132     default:
1133         return -EINVAL;
1134     }
1135 }
1136 
1137 static const struct file_operations tap_fops = {
1138     .owner      = THIS_MODULE,
1139     .open       = tap_open,
1140     .release    = tap_release,
1141     .read_iter  = tap_read_iter,
1142     .write_iter = tap_write_iter,
1143     .poll       = tap_poll,
1144     .llseek     = no_llseek,
1145     .unlocked_ioctl = tap_ioctl,
1146     .compat_ioctl   = compat_ptr_ioctl,
1147 };
1148 
1149 static int tap_get_user_xdp(struct tap_queue *q, struct xdp_buff *xdp)
1150 {
1151     struct tun_xdp_hdr *hdr = xdp->data_hard_start;
1152     struct virtio_net_hdr *gso = &hdr->gso;
1153     int buflen = hdr->buflen;
1154     int vnet_hdr_len = 0;
1155     struct tap_dev *tap;
1156     struct sk_buff *skb;
1157     int err, depth;
1158 
1159     if (q->flags & IFF_VNET_HDR)
1160         vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
1161 
1162     skb = build_skb(xdp->data_hard_start, buflen);
1163     if (!skb) {
1164         err = -ENOMEM;
1165         goto err;
1166     }
1167 
1168     skb_reserve(skb, xdp->data - xdp->data_hard_start);
1169     skb_put(skb, xdp->data_end - xdp->data);
1170 
1171     skb_set_network_header(skb, ETH_HLEN);
1172     skb_reset_mac_header(skb);
1173     skb->protocol = eth_hdr(skb)->h_proto;
1174 
1175     if (vnet_hdr_len) {
1176         err = virtio_net_hdr_to_skb(skb, gso, tap_is_little_endian(q));
1177         if (err)
1178             goto err_kfree;
1179     }
1180 
1181     /* Move network header to the right position for VLAN tagged packets */
1182     if (eth_type_vlan(skb->protocol) &&
1183         __vlan_get_protocol(skb, skb->protocol, &depth) != 0)
1184         skb_set_network_header(skb, depth);
1185 
1186     rcu_read_lock();
1187     tap = rcu_dereference(q->tap);
1188     if (tap) {
1189         skb->dev = tap->dev;
1190         skb_probe_transport_header(skb);
1191         dev_queue_xmit(skb);
1192     } else {
1193         kfree_skb(skb);
1194     }
1195     rcu_read_unlock();
1196 
1197     return 0;
1198 
1199 err_kfree:
1200     kfree_skb(skb);
1201 err:
1202     rcu_read_lock();
1203     tap = rcu_dereference(q->tap);
1204     if (tap && tap->count_tx_dropped)
1205         tap->count_tx_dropped(tap);
1206     rcu_read_unlock();
1207     return err;
1208 }
1209 
1210 static int tap_sendmsg(struct socket *sock, struct msghdr *m,
1211                size_t total_len)
1212 {
1213     struct tap_queue *q = container_of(sock, struct tap_queue, sock);
1214     struct tun_msg_ctl *ctl = m->msg_control;
1215     struct xdp_buff *xdp;
1216     int i;
1217 
1218     if (m->msg_controllen == sizeof(struct tun_msg_ctl) &&
1219         ctl && ctl->type == TUN_MSG_PTR) {
1220         for (i = 0; i < ctl->num; i++) {
1221             xdp = &((struct xdp_buff *)ctl->ptr)[i];
1222             tap_get_user_xdp(q, xdp);
1223         }
1224         return 0;
1225     }
1226 
1227     return tap_get_user(q, ctl ? ctl->ptr : NULL, &m->msg_iter,
1228                 m->msg_flags & MSG_DONTWAIT);
1229 }
1230 
1231 static int tap_recvmsg(struct socket *sock, struct msghdr *m,
1232                size_t total_len, int flags)
1233 {
1234     struct tap_queue *q = container_of(sock, struct tap_queue, sock);
1235     struct sk_buff *skb = m->msg_control;
1236     int ret;
1237     if (flags & ~(MSG_DONTWAIT|MSG_TRUNC)) {
1238         kfree_skb(skb);
1239         return -EINVAL;
1240     }
1241     ret = tap_do_read(q, &m->msg_iter, flags & MSG_DONTWAIT, skb);
1242     if (ret > total_len) {
1243         m->msg_flags |= MSG_TRUNC;
1244         ret = flags & MSG_TRUNC ? ret : total_len;
1245     }
1246     return ret;
1247 }
1248 
1249 static int tap_peek_len(struct socket *sock)
1250 {
1251     struct tap_queue *q = container_of(sock, struct tap_queue,
1252                            sock);
1253     return PTR_RING_PEEK_CALL(&q->ring, __skb_array_len_with_tag);
1254 }
1255 
1256 /* Ops structure to mimic raw sockets with tun */
1257 static const struct proto_ops tap_socket_ops = {
1258     .sendmsg = tap_sendmsg,
1259     .recvmsg = tap_recvmsg,
1260     .peek_len = tap_peek_len,
1261 };
1262 
1263 /* Get an underlying socket object from tun file.  Returns error unless file is
1264  * attached to a device.  The returned object works like a packet socket, it
1265  * can be used for sock_sendmsg/sock_recvmsg.  The caller is responsible for
1266  * holding a reference to the file for as long as the socket is in use. */
1267 struct socket *tap_get_socket(struct file *file)
1268 {
1269     struct tap_queue *q;
1270     if (file->f_op != &tap_fops)
1271         return ERR_PTR(-EINVAL);
1272     q = file->private_data;
1273     if (!q)
1274         return ERR_PTR(-EBADFD);
1275     return &q->sock;
1276 }
1277 EXPORT_SYMBOL_GPL(tap_get_socket);
1278 
1279 struct ptr_ring *tap_get_ptr_ring(struct file *file)
1280 {
1281     struct tap_queue *q;
1282 
1283     if (file->f_op != &tap_fops)
1284         return ERR_PTR(-EINVAL);
1285     q = file->private_data;
1286     if (!q)
1287         return ERR_PTR(-EBADFD);
1288     return &q->ring;
1289 }
1290 EXPORT_SYMBOL_GPL(tap_get_ptr_ring);
1291 
1292 int tap_queue_resize(struct tap_dev *tap)
1293 {
1294     struct net_device *dev = tap->dev;
1295     struct tap_queue *q;
1296     struct ptr_ring **rings;
1297     int n = tap->numqueues;
1298     int ret, i = 0;
1299 
1300     rings = kmalloc_array(n, sizeof(*rings), GFP_KERNEL);
1301     if (!rings)
1302         return -ENOMEM;
1303 
1304     list_for_each_entry(q, &tap->queue_list, next)
1305         rings[i++] = &q->ring;
1306 
1307     ret = ptr_ring_resize_multiple(rings, n,
1308                        dev->tx_queue_len, GFP_KERNEL,
1309                        __skb_array_destroy_skb);
1310 
1311     kfree(rings);
1312     return ret;
1313 }
1314 EXPORT_SYMBOL_GPL(tap_queue_resize);
1315 
1316 static int tap_list_add(dev_t major, const char *device_name)
1317 {
1318     struct major_info *tap_major;
1319 
1320     tap_major = kzalloc(sizeof(*tap_major), GFP_ATOMIC);
1321     if (!tap_major)
1322         return -ENOMEM;
1323 
1324     tap_major->major = MAJOR(major);
1325 
1326     idr_init(&tap_major->minor_idr);
1327     spin_lock_init(&tap_major->minor_lock);
1328 
1329     tap_major->device_name = device_name;
1330 
1331     list_add_tail_rcu(&tap_major->next, &major_list);
1332     return 0;
1333 }
1334 
1335 int tap_create_cdev(struct cdev *tap_cdev, dev_t *tap_major,
1336             const char *device_name, struct module *module)
1337 {
1338     int err;
1339 
1340     err = alloc_chrdev_region(tap_major, 0, TAP_NUM_DEVS, device_name);
1341     if (err)
1342         goto out1;
1343 
1344     cdev_init(tap_cdev, &tap_fops);
1345     tap_cdev->owner = module;
1346     err = cdev_add(tap_cdev, *tap_major, TAP_NUM_DEVS);
1347     if (err)
1348         goto out2;
1349 
1350     err =  tap_list_add(*tap_major, device_name);
1351     if (err)
1352         goto out3;
1353 
1354     return 0;
1355 
1356 out3:
1357     cdev_del(tap_cdev);
1358 out2:
1359     unregister_chrdev_region(*tap_major, TAP_NUM_DEVS);
1360 out1:
1361     return err;
1362 }
1363 EXPORT_SYMBOL_GPL(tap_create_cdev);
1364 
1365 void tap_destroy_cdev(dev_t major, struct cdev *tap_cdev)
1366 {
1367     struct major_info *tap_major, *tmp;
1368 
1369     cdev_del(tap_cdev);
1370     unregister_chrdev_region(major, TAP_NUM_DEVS);
1371     list_for_each_entry_safe(tap_major, tmp, &major_list, next) {
1372         if (tap_major->major == MAJOR(major)) {
1373             idr_destroy(&tap_major->minor_idr);
1374             list_del_rcu(&tap_major->next);
1375             kfree_rcu(tap_major, rcu);
1376         }
1377     }
1378 }
1379 EXPORT_SYMBOL_GPL(tap_destroy_cdev);
1380 
1381 MODULE_AUTHOR("Arnd Bergmann <arnd@arndb.de>");
1382 MODULE_AUTHOR("Sainath Grandhi <sainath.grandhi@intel.com>");
1383 MODULE_LICENSE("GPL");
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