From d9d52b5178af586d679c1052fb161ee05ea2e83f Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Wed, 17 Mar 2010 17:45:01 +0200 Subject: [PATCH 1/2] tun: add ioctl to modify vnet header size virtio added mergeable buffers mode where 2 bytes of extra info is put after vnet header but before actual data (tun does not need this data). In hindsight, it would have been better to add the new info *before* the packet: as it is, users need a lot of tricky code to skip the extra 2 bytes in the middle of the iovec, and in fact applications seem to get it wrong, and only work with specific iovec layout. The fact we might need to split iovec also means we might in theory overflow iovec max size. This patch adds a simpler way for applications to handle this, and future proofs the interface against further extensions, by making the size of the virtio net header configurable from userspace. As a result, tun driver will simply skip the extra 2 bytes on both input and output. Signed-off-by: Michael S. Tsirkin Acked-by: David S. Miller --- drivers/net/tun.c | 32 ++++++++++++++++++++++++++++---- include/linux/if_tun.h | 2 ++ 2 files changed, 30 insertions(+), 4 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index e525a6cf5587..6b150c072a41 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -110,6 +110,9 @@ struct tun_struct { struct tap_filter txflt; struct socket socket; struct socket_wq wq; + + int vnet_hdr_sz; + #ifdef TUN_DEBUG int debug; #endif @@ -563,7 +566,7 @@ static __inline__ ssize_t tun_get_user(struct tun_struct *tun, } if (tun->flags & TUN_VNET_HDR) { - if ((len -= sizeof(gso)) > count) + if ((len -= tun->vnet_hdr_sz) > count) return -EINVAL; if (memcpy_fromiovecend((void *)&gso, iv, offset, sizeof(gso))) @@ -575,7 +578,7 @@ static __inline__ ssize_t tun_get_user(struct tun_struct *tun, if (gso.hdr_len > len) return -EINVAL; - offset += sizeof(gso); + offset += tun->vnet_hdr_sz; } if ((tun->flags & TUN_TYPE_MASK) == TUN_TAP_DEV) { @@ -718,7 +721,7 @@ static __inline__ ssize_t tun_put_user(struct tun_struct *tun, if (tun->flags & TUN_VNET_HDR) { struct virtio_net_hdr gso = { 0 }; /* no info leak */ - if ((len -= sizeof(gso)) < 0) + if ((len -= tun->vnet_hdr_sz) < 0) return -EINVAL; if (skb_is_gso(skb)) { @@ -749,7 +752,7 @@ static __inline__ ssize_t tun_put_user(struct tun_struct *tun, if (unlikely(memcpy_toiovecend(iv, (void *)&gso, total, sizeof(gso)))) return -EFAULT; - total += sizeof(gso); + total += tun->vnet_hdr_sz; } len = min_t(int, skb->len, len); @@ -1035,6 +1038,7 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr) tun->dev = dev; tun->flags = flags; tun->txflt.count = 0; + tun->vnet_hdr_sz = sizeof(struct virtio_net_hdr); err = -ENOMEM; sk = sk_alloc(net, AF_UNSPEC, GFP_KERNEL, &tun_proto); @@ -1177,6 +1181,7 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd, struct sock_fprog fprog; struct ifreq ifr; int sndbuf; + int vnet_hdr_sz; int ret; if (cmd == TUNSETIFF || _IOC_TYPE(cmd) == 0x89) @@ -1322,6 +1327,25 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd, tun->socket.sk->sk_sndbuf = sndbuf; 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 TUNATTACHFILTER: /* Can be set only for TAPs */ ret = -EINVAL; diff --git a/include/linux/if_tun.h b/include/linux/if_tun.h index 1350a246893a..06b1829731fd 100644 --- a/include/linux/if_tun.h +++ b/include/linux/if_tun.h @@ -51,6 +51,8 @@ #define TUNSETSNDBUF _IOW('T', 212, int) #define TUNATTACHFILTER _IOW('T', 213, struct sock_fprog) #define TUNDETACHFILTER _IOW('T', 214, struct sock_fprog) +#define TUNGETVNETHDRSZ _IOR('T', 215, int) +#define TUNSETVNETHDRSZ _IOW('T', 216, int) /* TUNSETIFF ifr flags */ #define IFF_TUN 0x0001 From 55afbd0810922afe456f9e4e3abc84d69d3f8a15 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Thu, 29 Apr 2010 13:50:48 +0300 Subject: [PATCH 2/2] macvtap: add ioctl to modify vnet header size This adds TUNSETVNETHDRSZ/TUNGETVNETHDRSZ support to macvtap. Signed-off-by: Michael S. Tsirkin Acked-by: Arnd Bergmann Acked-by: David S. Miller --- drivers/net/macvtap.c | 27 +++++++++++++++++++++++---- 1 file changed, 23 insertions(+), 4 deletions(-) diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index 1c4110df343e..a8a94e2f6ddc 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -38,6 +38,7 @@ struct macvtap_queue { struct sock sk; struct socket sock; struct socket_wq wq; + int vnet_hdr_sz; struct macvlan_dev *vlan; struct file *file; unsigned int flags; @@ -285,6 +286,7 @@ static int macvtap_open(struct inode *inode, struct file *file) sock_init_data(&q->sock, &q->sk); q->sk.sk_write_space = macvtap_sock_write_space; q->flags = IFF_VNET_HDR | IFF_NO_PI | IFF_TAP; + q->vnet_hdr_sz = sizeof(struct virtio_net_hdr); err = macvtap_set_queue(dev, file, q); if (err) @@ -445,14 +447,14 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, int vnet_hdr_len = 0; if (q->flags & IFF_VNET_HDR) { - vnet_hdr_len = sizeof(vnet_hdr); + vnet_hdr_len = q->vnet_hdr_sz; err = -EINVAL; if ((len -= vnet_hdr_len) < 0) goto err; err = memcpy_fromiovecend((void *)&vnet_hdr, iv, 0, - vnet_hdr_len); + sizeof(vnet_hdr)); if (err < 0) goto err; if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) && @@ -534,7 +536,7 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q, if (q->flags & IFF_VNET_HDR) { struct virtio_net_hdr vnet_hdr; - vnet_hdr_len = sizeof (vnet_hdr); + vnet_hdr_len = q->vnet_hdr_sz; if ((len -= vnet_hdr_len) < 0) return -EINVAL; @@ -542,7 +544,7 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q, if (ret) return ret; - if (memcpy_toiovecend(iv, (void *)&vnet_hdr, 0, vnet_hdr_len)) + if (memcpy_toiovecend(iv, (void *)&vnet_hdr, 0, sizeof(vnet_hdr))) return -EFAULT; } @@ -627,6 +629,8 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd, struct ifreq __user *ifr = argp; unsigned int __user *up = argp; unsigned int u; + int __user *sp = argp; + int s; int ret; switch (cmd) { @@ -672,6 +676,21 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd, q->sk.sk_sndbuf = u; 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 TUNSETOFFLOAD: /* let the user check for future flags */ if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |