Both tun and tap exposes the same set of virtio-net-related features.
Unify their implementations to ease future changes.

Signed-off-by: Akihiko Odaki <akihiko.od...@daynix.com>
---
 MAINTAINERS            |   1 +
 drivers/net/tap.c      | 172 ++++++----------------------------------
 drivers/net/tun.c      | 208 ++++++++-----------------------------------------
 drivers/net/tun_vnet.h | 181 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 238 insertions(+), 324 deletions(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index cc40a9d9b8cd..209b4e1cccb1 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -23338,6 +23338,7 @@ F:      Documentation/networking/tuntap.rst
 F:     arch/um/os-Linux/drivers/
 F:     drivers/net/tap.c
 F:     drivers/net/tun.c
+F:     drivers/net/tun_vnet.h
 
 TURBOCHANNEL SUBSYSTEM
 M:     "Maciej W. Rozycki" <ma...@orcam.me.uk>
diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index 77574f7a3bd4..9a34ceed0c2c 100644
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -26,74 +26,9 @@
 #include <linux/virtio_net.h>
 #include <linux/skb_array.h>
 
-#define TAP_IFFEATURES (IFF_VNET_HDR | IFF_MULTI_QUEUE)
-
-#define TAP_VNET_LE 0x80000000
-#define TAP_VNET_BE 0x40000000
-
-#ifdef CONFIG_TUN_VNET_CROSS_LE
-static inline bool tap_legacy_is_little_endian(struct tap_queue *q)
-{
-       return q->flags & TAP_VNET_BE ? false :
-               virtio_legacy_is_little_endian();
-}
-
-static long tap_get_vnet_be(struct tap_queue *q, int __user *sp)
-{
-       int s = !!(q->flags & TAP_VNET_BE);
-
-       if (put_user(s, sp))
-               return -EFAULT;
-
-       return 0;
-}
-
-static long tap_set_vnet_be(struct tap_queue *q, int __user *sp)
-{
-       int s;
-
-       if (get_user(s, sp))
-               return -EFAULT;
-
-       if (s)
-               q->flags |= TAP_VNET_BE;
-       else
-               q->flags &= ~TAP_VNET_BE;
-
-       return 0;
-}
-#else
-static inline bool tap_legacy_is_little_endian(struct tap_queue *q)
-{
-       return virtio_legacy_is_little_endian();
-}
-
-static long tap_get_vnet_be(struct tap_queue *q, int __user *argp)
-{
-       return -EINVAL;
-}
+#include "tun_vnet.h"
 
-static long tap_set_vnet_be(struct tap_queue *q, int __user *argp)
-{
-       return -EINVAL;
-}
-#endif /* CONFIG_TUN_VNET_CROSS_LE */
-
-static inline bool tap_is_little_endian(struct tap_queue *q)
-{
-       return q->flags & TAP_VNET_LE ||
-               tap_legacy_is_little_endian(q);
-}
-
-static inline u16 tap16_to_cpu(struct tap_queue *q, __virtio16 val)
-{
-       return __virtio16_to_cpu(tap_is_little_endian(q), val);
-}
-
-static inline __virtio16 cpu_to_tap16(struct tap_queue *q, u16 val)
-{
-       return __cpu_to_virtio16(tap_is_little_endian(q), val);
-}
+#define TAP_IFFEATURES (IFF_VNET_HDR | IFF_MULTI_QUEUE)
 
 static struct proto tap_proto = {
        .name = "tap",
@@ -641,10 +576,10 @@ static ssize_t tap_get_user(struct tap_queue *q, void 
*msg_control,
        struct sk_buff *skb;
        struct tap_dev *tap;
        unsigned long total_len = iov_iter_count(from);
-       unsigned long len = total_len;
+       unsigned long len;
        int err;
        struct virtio_net_hdr vnet_hdr = { 0 };
-       int vnet_hdr_len = 0;
+       int hdr_len;
        int copylen = 0;
        int depth;
        bool zerocopy = false;
@@ -652,38 +587,20 @@ static ssize_t tap_get_user(struct tap_queue *q, void 
*msg_control,
        enum skb_drop_reason drop_reason;
 
        if (q->flags & IFF_VNET_HDR) {
-               vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
-
-               err = -EINVAL;
-               if (len < vnet_hdr_len)
-                       goto err;
-               len -= vnet_hdr_len;
-
-               err = -EFAULT;
-               if (!copy_from_iter_full(&vnet_hdr, sizeof(vnet_hdr), from))
-                       goto err;
-               iov_iter_advance(from, vnet_hdr_len - sizeof(vnet_hdr));
-               if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
-                    tap16_to_cpu(q, vnet_hdr.csum_start) +
-                    tap16_to_cpu(q, vnet_hdr.csum_offset) + 2 >
-                            tap16_to_cpu(q, vnet_hdr.hdr_len))
-                       vnet_hdr.hdr_len = cpu_to_tap16(q,
-                                tap16_to_cpu(q, vnet_hdr.csum_start) +
-                                tap16_to_cpu(q, vnet_hdr.csum_offset) + 2);
-               err = -EINVAL;
-               if (tap16_to_cpu(q, vnet_hdr.hdr_len) > len)
+               hdr_len = tun_vnet_hdr_get(READ_ONCE(q->vnet_hdr_sz), q->flags, 
from, &vnet_hdr);
+               if (hdr_len < 0) {
+                       err = hdr_len;
                        goto err;
+               }
+       } else {
+               hdr_len = 0;
        }
 
-       err = -EINVAL;
-       if (unlikely(len < ETH_HLEN))
-               goto err;
-
+       len = iov_iter_count(from);
        if (msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) {
                struct iov_iter i;
 
-               copylen = vnet_hdr.hdr_len ?
-                       tap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN;
+               copylen = hdr_len ? hdr_len : GOODCOPY_LEN;
                if (copylen > good_linear)
                        copylen = good_linear;
                else if (copylen < ETH_HLEN)
@@ -697,7 +614,7 @@ static ssize_t tap_get_user(struct tap_queue *q, void 
*msg_control,
 
        if (!zerocopy) {
                copylen = len;
-               linear = tap16_to_cpu(q, vnet_hdr.hdr_len);
+               linear = hdr_len;
                if (linear > good_linear)
                        linear = good_linear;
                else if (linear < ETH_HLEN)
@@ -732,9 +649,8 @@ static ssize_t tap_get_user(struct tap_queue *q, void 
*msg_control,
        }
        skb->dev = tap->dev;
 
-       if (vnet_hdr_len) {
-               err = virtio_net_hdr_to_skb(skb, &vnet_hdr,
-                                           tap_is_little_endian(q));
+       if (q->flags & IFF_VNET_HDR) {
+               err = tun_vnet_hdr_to_skb(q->flags, skb, &vnet_hdr);
                if (err) {
                        rcu_read_unlock();
                        drop_reason = SKB_DROP_REASON_DEV_HDR;
@@ -797,23 +713,17 @@ static ssize_t tap_put_user(struct tap_queue *q,
        int total;
 
        if (q->flags & IFF_VNET_HDR) {
-               int vlan_hlen = skb_vlan_tag_present(skb) ? VLAN_HLEN : 0;
                struct virtio_net_hdr vnet_hdr;
 
                vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
-               if (iov_iter_count(iter) < vnet_hdr_len)
-                       return -EINVAL;
-
-               if (virtio_net_hdr_from_skb(skb, &vnet_hdr,
-                                           tap_is_little_endian(q), true,
-                                           vlan_hlen))
-                       BUG();
 
-               if (copy_to_iter(&vnet_hdr, sizeof(vnet_hdr), iter) !=
-                   sizeof(vnet_hdr))
-                       return -EFAULT;
+               ret = tun_vnet_hdr_from_skb(q->flags, NULL, skb, &vnet_hdr);
+               if (ret < 0)
+                       goto done;
 
-               iov_iter_advance(iter, vnet_hdr_len - sizeof(vnet_hdr));
+               ret = tun_vnet_hdr_put(vnet_hdr_len, iter, &vnet_hdr);
+               if (ret < 0)
+                       goto done;
        }
        total = vnet_hdr_len;
        total += skb->len;
@@ -1072,42 +982,6 @@ static long tap_ioctl(struct file *file, unsigned int cmd,
                q->sk.sk_sndbuf = s;
                return 0;
 
-       case TUNGETVNETHDRSZ:
-               s = q->vnet_hdr_sz;
-               if (put_user(s, sp))
-                       return -EFAULT;
-               return 0;
-
-       case TUNSETVNETHDRSZ:
-               if (get_user(s, sp))
-                       return -EFAULT;
-               if (s < (int)sizeof(struct virtio_net_hdr))
-                       return -EINVAL;
-
-               q->vnet_hdr_sz = s;
-               return 0;
-
-       case TUNGETVNETLE:
-               s = !!(q->flags & TAP_VNET_LE);
-               if (put_user(s, sp))
-                       return -EFAULT;
-               return 0;
-
-       case TUNSETVNETLE:
-               if (get_user(s, sp))
-                       return -EFAULT;
-               if (s)
-                       q->flags |= TAP_VNET_LE;
-               else
-                       q->flags &= ~TAP_VNET_LE;
-               return 0;
-
-       case TUNGETVNETBE:
-               return tap_get_vnet_be(q, sp);
-
-       case TUNSETVNETBE:
-               return tap_set_vnet_be(q, sp);
-
        case TUNSETOFFLOAD:
                /* let the user check for future flags */
                if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
@@ -1151,7 +1025,7 @@ static long tap_ioctl(struct file *file, unsigned int cmd,
                return ret;
 
        default:
-               return -EINVAL;
+               return tun_vnet_ioctl(&q->vnet_hdr_sz, &q->flags, cmd, sp);
        }
 }
 
@@ -1199,7 +1073,7 @@ static int tap_get_user_xdp(struct tap_queue *q, struct 
xdp_buff *xdp)
        skb->protocol = eth_hdr(skb)->h_proto;
 
        if (vnet_hdr_len) {
-               err = virtio_net_hdr_to_skb(skb, gso, tap_is_little_endian(q));
+               err = tun_vnet_hdr_to_skb(q->flags, skb, gso);
                if (err)
                        goto err_kfree;
        }
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 1d06c560c5e6..dd8799d19518 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -83,6 +83,8 @@
 #include <linux/uaccess.h>
 #include <linux/proc_fs.h>
 
+#include "tun_vnet.h"
+
 static void tun_default_link_ksettings(struct net_device *dev,
                                       struct ethtool_link_ksettings *cmd);
 
@@ -94,9 +96,6 @@ static void tun_default_link_ksettings(struct net_device *dev,
  * overload it to mean fasync when stored there.
  */
 #define TUN_FASYNC     IFF_ATTACH_QUEUE
-/* High bits in flags field are unused. */
-#define TUN_VNET_LE     0x80000000
-#define TUN_VNET_BE     0x40000000
 
 #define TUN_FEATURES (IFF_NO_PI | IFF_ONE_QUEUE | IFF_VNET_HDR | \
                      IFF_MULTI_QUEUE | IFF_NAPI | IFF_NAPI_FRAGS)
@@ -298,70 +297,6 @@ static bool tun_napi_frags_enabled(const struct tun_file 
*tfile)
        return tfile->napi_frags_enabled;
 }
 
-#ifdef CONFIG_TUN_VNET_CROSS_LE
-static inline bool tun_legacy_is_little_endian(struct tun_struct *tun)
-{
-       return tun->flags & TUN_VNET_BE ? false :
-               virtio_legacy_is_little_endian();
-}
-
-static long tun_get_vnet_be(struct tun_struct *tun, int __user *argp)
-{
-       int be = !!(tun->flags & TUN_VNET_BE);
-
-       if (put_user(be, argp))
-               return -EFAULT;
-
-       return 0;
-}
-
-static long tun_set_vnet_be(struct tun_struct *tun, int __user *argp)
-{
-       int be;
-
-       if (get_user(be, argp))
-               return -EFAULT;
-
-       if (be)
-               tun->flags |= TUN_VNET_BE;
-       else
-               tun->flags &= ~TUN_VNET_BE;
-
-       return 0;
-}
-#else
-static inline bool tun_legacy_is_little_endian(struct tun_struct *tun)
-{
-       return virtio_legacy_is_little_endian();
-}
-
-static long tun_get_vnet_be(struct tun_struct *tun, int __user *argp)
-{
-       return -EINVAL;
-}
-
-static long tun_set_vnet_be(struct tun_struct *tun, int __user *argp)
-{
-       return -EINVAL;
-}
-#endif /* CONFIG_TUN_VNET_CROSS_LE */
-
-static inline bool tun_is_little_endian(struct tun_struct *tun)
-{
-       return tun->flags & TUN_VNET_LE ||
-               tun_legacy_is_little_endian(tun);
-}
-
-static inline u16 tun16_to_cpu(struct tun_struct *tun, __virtio16 val)
-{
-       return __virtio16_to_cpu(tun_is_little_endian(tun), val);
-}
-
-static inline __virtio16 cpu_to_tun16(struct tun_struct *tun, u16 val)
-{
-       return __cpu_to_virtio16(tun_is_little_endian(tun), val);
-}
-
 static inline u32 tun_hashfn(u32 rxhash)
 {
        return rxhash & TUN_MASK_FLOW_ENTRIES;
@@ -1751,8 +1686,9 @@ static ssize_t tun_get_user(struct tun_struct *tun, 
struct tun_file *tfile,
        struct tun_pi pi = { 0, cpu_to_be16(ETH_P_IP) };
        struct sk_buff *skb;
        size_t total_len = iov_iter_count(from);
-       size_t len = total_len, align = tun->align, linear;
+       size_t len, align = tun->align, linear;
        struct virtio_net_hdr gso = { 0 };
+       int hdr_len;
        int good_linear;
        int copylen;
        bool zerocopy = false;
@@ -1763,37 +1699,25 @@ static ssize_t tun_get_user(struct tun_struct *tun, 
struct tun_file *tfile,
        enum skb_drop_reason drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
 
        if (!(tun->flags & IFF_NO_PI)) {
-               if (len < sizeof(pi))
+               if (iov_iter_count(from) < sizeof(pi))
                        return -EINVAL;
-               len -= sizeof(pi);
 
                if (!copy_from_iter_full(&pi, sizeof(pi), from))
                        return -EFAULT;
        }
 
        if (tun->flags & IFF_VNET_HDR) {
-               int vnet_hdr_sz = READ_ONCE(tun->vnet_hdr_sz);
-
-               if (len < vnet_hdr_sz)
-                       return -EINVAL;
-               len -= vnet_hdr_sz;
-
-               if (!copy_from_iter_full(&gso, sizeof(gso), from))
-                       return -EFAULT;
-
-               if ((gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
-                   tun16_to_cpu(tun, gso.csum_start) + tun16_to_cpu(tun, 
gso.csum_offset) + 2 > tun16_to_cpu(tun, gso.hdr_len))
-                       gso.hdr_len = cpu_to_tun16(tun, tun16_to_cpu(tun, 
gso.csum_start) + tun16_to_cpu(tun, gso.csum_offset) + 2);
-
-               if (tun16_to_cpu(tun, gso.hdr_len) > len)
-                       return -EINVAL;
-               iov_iter_advance(from, vnet_hdr_sz - sizeof(gso));
+               hdr_len = tun_vnet_hdr_get(READ_ONCE(tun->vnet_hdr_sz), 
tun->flags, from, &gso);
+               if (hdr_len < 0)
+                       return hdr_len;
+       } else {
+               hdr_len = 0;
        }
 
+       len = iov_iter_count(from);
        if ((tun->flags & TUN_TYPE_MASK) == IFF_TAP) {
                align += NET_IP_ALIGN;
-               if (unlikely(len < ETH_HLEN ||
-                            (gso.hdr_len && tun16_to_cpu(tun, gso.hdr_len) < 
ETH_HLEN)))
+               if (unlikely(len < ETH_HLEN || (hdr_len && hdr_len < ETH_HLEN)))
                        return -EINVAL;
        }
 
@@ -1806,7 +1730,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, 
struct tun_file *tfile,
                 * enough room for skb expand head in case it is used.
                 * The rest of the buffer is mapped from userspace.
                 */
-               copylen = gso.hdr_len ? tun16_to_cpu(tun, gso.hdr_len) : 
GOODCOPY_LEN;
+               copylen = hdr_len ? hdr_len : GOODCOPY_LEN;
                if (copylen > good_linear)
                        copylen = good_linear;
                linear = copylen;
@@ -1829,10 +1753,10 @@ static ssize_t tun_get_user(struct tun_struct *tun, 
struct tun_file *tfile,
        } else {
                if (!zerocopy) {
                        copylen = len;
-                       if (tun16_to_cpu(tun, gso.hdr_len) > good_linear)
+                       if (hdr_len > good_linear)
                                linear = good_linear;
                        else
-                               linear = tun16_to_cpu(tun, gso.hdr_len);
+                               linear = hdr_len;
                }
 
                if (frags) {
@@ -1867,7 +1791,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, 
struct tun_file *tfile,
                }
        }
 
-       if (virtio_net_hdr_to_skb(skb, &gso, tun_is_little_endian(tun))) {
+       if (tun_vnet_hdr_to_skb(tun->flags, skb, &gso)) {
                atomic_long_inc(&tun->rx_frame_errors);
                err = -EINVAL;
                goto free_skb;
@@ -2060,29 +1984,27 @@ static ssize_t tun_put_user_xdp(struct tun_struct *tun,
                                struct xdp_frame *xdp_frame,
                                struct iov_iter *iter)
 {
+       int ret;
        int vnet_hdr_sz = 0;
        size_t size = xdp_frame->len;
-       size_t ret;
+       size_t total;
 
        if (tun->flags & IFF_VNET_HDR) {
                struct virtio_net_hdr gso = { 0 };
 
                vnet_hdr_sz = READ_ONCE(tun->vnet_hdr_sz);
-               if (unlikely(iov_iter_count(iter) < vnet_hdr_sz))
-                       return -EINVAL;
-               if (unlikely(copy_to_iter(&gso, sizeof(gso), iter) !=
-                            sizeof(gso)))
-                       return -EFAULT;
-               iov_iter_advance(iter, vnet_hdr_sz - sizeof(gso));
+               ret = tun_vnet_hdr_put(vnet_hdr_sz, iter, &gso);
+               if (ret < 0)
+                       return ret;
        }
 
-       ret = copy_to_iter(xdp_frame->data, size, iter) + vnet_hdr_sz;
+       total = copy_to_iter(xdp_frame->data, size, iter) + vnet_hdr_sz;
 
        preempt_disable();
-       dev_sw_netstats_tx_add(tun->dev, 1, ret);
+       dev_sw_netstats_tx_add(tun->dev, 1, total);
        preempt_enable();
 
-       return ret;
+       return total;
 }
 
 /* Put packet to the user space buffer */
@@ -2096,6 +2018,7 @@ static ssize_t tun_put_user(struct tun_struct *tun,
        int vlan_offset = 0;
        int vlan_hlen = 0;
        int vnet_hdr_sz = 0;
+       int ret;
 
        if (skb_vlan_tag_present(skb))
                vlan_hlen = VLAN_HLEN;
@@ -2122,31 +2045,13 @@ static ssize_t tun_put_user(struct tun_struct *tun,
        if (vnet_hdr_sz) {
                struct virtio_net_hdr gso;
 
-               if (iov_iter_count(iter) < vnet_hdr_sz)
-                       return -EINVAL;
-
-               if (virtio_net_hdr_from_skb(skb, &gso,
-                                           tun_is_little_endian(tun), true,
-                                           vlan_hlen)) {
-                       struct skb_shared_info *sinfo = skb_shinfo(skb);
-
-                       if (net_ratelimit()) {
-                               netdev_err(tun->dev, "unexpected GSO type: 
0x%x, gso_size %d, hdr_len %d\n",
-                                          sinfo->gso_type, tun16_to_cpu(tun, 
gso.gso_size),
-                                          tun16_to_cpu(tun, gso.hdr_len));
-                               print_hex_dump(KERN_ERR, "tun: ",
-                                              DUMP_PREFIX_NONE,
-                                              16, 1, skb->head,
-                                              min((int)tun16_to_cpu(tun, 
gso.hdr_len), 64), true);
-                       }
-                       WARN_ON_ONCE(1);
-                       return -EINVAL;
-               }
-
-               if (copy_to_iter(&gso, sizeof(gso), iter) != sizeof(gso))
-                       return -EFAULT;
+               ret = tun_vnet_hdr_from_skb(tun->flags, tun->dev, skb, &gso);
+               if (ret < 0)
+                       goto done;
 
-               iov_iter_advance(iter, vnet_hdr_sz - sizeof(gso));
+               ret = tun_vnet_hdr_put(vnet_hdr_sz, iter, &gso);
+               if (ret < 0)
+                       goto done;
        }
 
        if (vlan_hlen) {
@@ -2506,7 +2411,7 @@ static int tun_xdp_one(struct tun_struct *tun,
        skb_reserve(skb, xdp->data - xdp->data_hard_start);
        skb_put(skb, xdp->data_end - xdp->data);
 
-       if (virtio_net_hdr_to_skb(skb, gso, tun_is_little_endian(tun))) {
+       if (tun_vnet_hdr_to_skb(tun->flags, skb, gso)) {
                atomic_long_inc(&tun->rx_frame_errors);
                kfree_skb(skb);
                ret = -EINVAL;
@@ -3090,8 +2995,6 @@ static long __tun_chr_ioctl(struct file *file, unsigned 
int cmd,
        kgid_t group;
        int ifindex;
        int sndbuf;
-       int vnet_hdr_sz;
-       int le;
        int ret;
        bool do_notify = false;
 
@@ -3298,50 +3201,6 @@ static long __tun_chr_ioctl(struct file *file, unsigned 
int cmd,
                tun_set_sndbuf(tun);
                break;
 
-       case TUNGETVNETHDRSZ:
-               vnet_hdr_sz = tun->vnet_hdr_sz;
-               if (copy_to_user(argp, &vnet_hdr_sz, sizeof(vnet_hdr_sz)))
-                       ret = -EFAULT;
-               break;
-
-       case TUNSETVNETHDRSZ:
-               if (copy_from_user(&vnet_hdr_sz, argp, sizeof(vnet_hdr_sz))) {
-                       ret = -EFAULT;
-                       break;
-               }
-               if (vnet_hdr_sz < (int)sizeof(struct virtio_net_hdr)) {
-                       ret = -EINVAL;
-                       break;
-               }
-
-               tun->vnet_hdr_sz = vnet_hdr_sz;
-               break;
-
-       case TUNGETVNETLE:
-               le = !!(tun->flags & TUN_VNET_LE);
-               if (put_user(le, (int __user *)argp))
-                       ret = -EFAULT;
-               break;
-
-       case TUNSETVNETLE:
-               if (get_user(le, (int __user *)argp)) {
-                       ret = -EFAULT;
-                       break;
-               }
-               if (le)
-                       tun->flags |= TUN_VNET_LE;
-               else
-                       tun->flags &= ~TUN_VNET_LE;
-               break;
-
-       case TUNGETVNETBE:
-               ret = tun_get_vnet_be(tun, argp);
-               break;
-
-       case TUNSETVNETBE:
-               ret = tun_set_vnet_be(tun, argp);
-               break;
-
        case TUNATTACHFILTER:
                /* Can be set only for TAPs */
                ret = -EINVAL;
@@ -3397,8 +3256,7 @@ static long __tun_chr_ioctl(struct file *file, unsigned 
int cmd,
                break;
 
        default:
-               ret = -EINVAL;
-               break;
+               ret = tun_vnet_ioctl(&tun->vnet_hdr_sz, &tun->flags, cmd, argp);
        }
 
        if (do_notify)
diff --git a/drivers/net/tun_vnet.h b/drivers/net/tun_vnet.h
new file mode 100644
index 000000000000..7c7f3f6d85e9
--- /dev/null
+++ b/drivers/net/tun_vnet.h
@@ -0,0 +1,181 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef TUN_VNET_H
+#define TUN_VNET_H
+
+/* High bits in flags field are unused. */
+#define TUN_VNET_LE 0x80000000
+#define TUN_VNET_BE 0x40000000
+
+static inline bool tun_vnet_legacy_is_little_endian(unsigned int flags)
+{
+       return !(IS_ENABLED(CONFIG_TUN_VNET_CROSS_LE) && (flags & TUN_VNET_BE)) 
&&
+              virtio_legacy_is_little_endian();
+}
+
+static inline long tun_vnet_get_be(int flags, int __user *sp)
+{
+       int s = !!(flags & TUN_VNET_BE);
+
+       if (!IS_ENABLED(CONFIG_TUN_VNET_CROSS_LE))
+               return -EINVAL;
+
+       if (put_user(s, sp))
+               return -EFAULT;
+
+       return 0;
+}
+
+static inline long tun_vnet_set_be(int *flags, int __user *sp)
+{
+       int s;
+
+       if (!IS_ENABLED(CONFIG_TUN_VNET_CROSS_LE))
+               return -EINVAL;
+
+       if (get_user(s, sp))
+               return -EFAULT;
+
+       if (s)
+               *flags |= TUN_VNET_BE;
+       else
+               *flags &= ~TUN_VNET_BE;
+
+       return 0;
+}
+
+static inline bool tun_vnet_is_little_endian(unsigned int flags)
+{
+       return flags & TUN_VNET_LE || tun_vnet_legacy_is_little_endian(flags);
+}
+
+static inline u16 tun_vnet16_to_cpu(unsigned int flags, __virtio16 val)
+{
+       return __virtio16_to_cpu(tun_vnet_is_little_endian(flags), val);
+}
+
+static inline __virtio16 cpu_to_tun_vnet16(unsigned int flags, u16 val)
+{
+       return __cpu_to_virtio16(tun_vnet_is_little_endian(flags), val);
+}
+
+static inline long tun_vnet_ioctl(int *sz, unsigned int *flags,
+                                 unsigned int cmd, int __user *sp)
+{
+       int s;
+
+       switch (cmd) {
+       case TUNGETVNETHDRSZ:
+               s = *sz;
+               if (put_user(s, sp))
+                       return -EFAULT;
+               return 0;
+
+       case TUNSETVNETHDRSZ:
+               if (get_user(s, sp))
+                       return -EFAULT;
+               if (s < (int)sizeof(struct virtio_net_hdr))
+                       return -EINVAL;
+
+               *sz = s;
+               return 0;
+
+       case TUNGETVNETLE:
+               s = !!(*flags & TUN_VNET_LE);
+               if (put_user(s, sp))
+                       return -EFAULT;
+               return 0;
+
+       case TUNSETVNETLE:
+               if (get_user(s, sp))
+                       return -EFAULT;
+               if (s)
+                       *flags |= TUN_VNET_LE;
+               else
+                       *flags &= ~TUN_VNET_LE;
+               return 0;
+
+       case TUNGETVNETBE:
+               return tun_vnet_get_be(*flags, sp);
+
+       case TUNSETVNETBE:
+               return tun_vnet_set_be(flags, sp);
+
+       default:
+               return -EINVAL;
+       }
+}
+
+static inline int tun_vnet_hdr_get(int sz, unsigned int flags,
+                                  struct iov_iter *from,
+                                  struct virtio_net_hdr *hdr)
+{
+       if (iov_iter_count(from) < sz)
+               return -EINVAL;
+
+       if (!copy_from_iter_full(hdr, sizeof(*hdr), from))
+               return -EFAULT;
+
+       iov_iter_advance(from, sz - sizeof(*hdr));
+       if ((hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
+           tun_vnet16_to_cpu(flags, hdr->csum_start) +
+           tun_vnet16_to_cpu(flags, hdr->csum_offset) + 2 >
+                    tun_vnet16_to_cpu(flags, hdr->hdr_len))
+               hdr->hdr_len = cpu_to_tun_vnet16(flags,
+                                                tun_vnet16_to_cpu(flags, 
hdr->csum_start) +
+                                                tun_vnet16_to_cpu(flags, 
hdr->csum_offset) + 2);
+       if (tun_vnet16_to_cpu(flags, hdr->hdr_len) > iov_iter_count(from))
+               return -EINVAL;
+
+       return tun_vnet16_to_cpu(flags, hdr->hdr_len);
+}
+
+static inline int tun_vnet_hdr_put(int sz, struct iov_iter *iter,
+                                  const struct virtio_net_hdr *hdr)
+{
+       if (iov_iter_count(iter) < sz)
+               return -EINVAL;
+
+       if (copy_to_iter(hdr, sizeof(*hdr), iter) != sizeof(*hdr))
+               return -EFAULT;
+
+       iov_iter_advance(iter, sz - sizeof(*hdr));
+
+       return 0;
+}
+
+static inline int tun_vnet_hdr_to_skb(unsigned int flags,
+                                     struct sk_buff *skb,
+                                     const struct virtio_net_hdr *hdr)
+{
+       return virtio_net_hdr_to_skb(skb, hdr, 
tun_vnet_is_little_endian(flags));
+}
+
+static inline int tun_vnet_hdr_from_skb(unsigned int flags,
+                                       const struct net_device *dev,
+                                       const struct sk_buff *skb,
+                                       struct virtio_net_hdr *hdr)
+{
+       int vlan_hlen = skb_vlan_tag_present(skb) ? VLAN_HLEN : 0;
+
+       if (virtio_net_hdr_from_skb(skb, hdr,
+                                   tun_vnet_is_little_endian(flags), true,
+                                   vlan_hlen)) {
+               struct skb_shared_info *sinfo = skb_shinfo(skb);
+
+               if (net_ratelimit()) {
+                       netdev_err(dev, "unexpected GSO type: 0x%x, gso_size 
%d, hdr_len %d\n",
+                                  sinfo->gso_type, tun_vnet16_to_cpu(flags, 
hdr->gso_size),
+                                  tun_vnet16_to_cpu(flags, hdr->hdr_len));
+                       print_hex_dump(KERN_ERR, "tun: ",
+                                      DUMP_PREFIX_NONE,
+                                      16, 1, skb->head,
+                                      min(tun_vnet16_to_cpu(flags, 
hdr->hdr_len), 64), true);
+               }
+               WARN_ON_ONCE(1);
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
+#endif /* TUN_VNET_H */

-- 
2.46.2


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