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SubjectRe: [net-next v5 6/7] tuntap: add ioctl to attach or detach a file form tuntap device
On Thu, Nov 01, 2012 at 01:46:01PM +0800, Jason Wang wrote:
> Sometimes usespace may need to active/deactive a queue, this could be done by
> detaching and attaching a file from tuntap device.
>
> This patch introduces a new ioctls - TUNSETQUEUE which could be used to do
> this. Flag IFF_ATTACH_QUEUE were introduced to do attaching while
> IFF_DETACH_QUEUE were introduced to do the detaching.
>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
> drivers/net/tun.c | 56 ++++++++++++++++++++++++++++++++++++------
> include/uapi/linux/if_tun.h | 3 ++
> 2 files changed, 51 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 2762c55..79b6f9e 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -195,6 +195,15 @@ static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb)
> return txq;
> }
>
> +static inline bool tun_not_capable(struct tun_struct *tun)
> +{
> + const struct cred *cred = current_cred();
> +
> + return ((uid_valid(tun->owner) && !uid_eq(cred->euid, tun->owner)) ||
> + (gid_valid(tun->group) && !in_egroup_p(tun->group))) &&
> + !capable(CAP_NET_ADMIN);
> +}
> +
> static void tun_set_real_num_queues(struct tun_struct *tun)
> {
> netif_set_real_num_tx_queues(tun->dev, tun->numqueues);
> @@ -1310,8 +1319,6 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
>
> dev = __dev_get_by_name(net, ifr->ifr_name);
> if (dev) {
> - const struct cred *cred = current_cred();
> -
> if (ifr->ifr_flags & IFF_TUN_EXCL)
> return -EBUSY;
> if ((ifr->ifr_flags & IFF_TUN) && dev->netdev_ops == &tun_netdev_ops)
> @@ -1321,9 +1328,7 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
> else
> return -EINVAL;
>
> - if (((uid_valid(tun->owner) && !uid_eq(cred->euid, tun->owner)) ||
> - (gid_valid(tun->group) && !in_egroup_p(tun->group))) &&
> - !capable(CAP_NET_ADMIN))
> + if (tun_not_capable(tun))
> return -EPERM;
> err = security_tun_dev_attach(tfile->socket.sk);
> if (err < 0)
> @@ -1530,6 +1535,40 @@ static void tun_set_sndbuf(struct tun_struct *tun)
> }
> }
>
> +static int tun_set_queue(struct file *file, struct ifreq *ifr)
> +{
> + struct tun_file *tfile = file->private_data;
> + struct tun_struct *tun;
> + struct net_device *dev;
> + int ret = 0;
> +
> + rtnl_lock();
> +
> + if (ifr->ifr_flags & IFF_ATTACH_QUEUE) {
> + dev = __dev_get_by_name(tfile->net, ifr->ifr_name);
> + if (!dev) {
> + ret = -EINVAL;
> + goto unlock;
> + }
> +
> + tun = netdev_priv(dev);
> + if (dev->netdev_ops != &tap_netdev_ops &&
> + dev->netdev_ops != &tun_netdev_ops)
> + ret = -EINVAL;
> + else if (tun_not_capable(tun))
> + ret = -EPERM;
> + else
> + ret = tun_attach(tun, file);

looks like we need to check
security_tun_dev_attach here as well.
As the patch is in net-next now we need a patch on top for that.



> + } else if (ifr->ifr_flags & IFF_DETACH_QUEUE)
> + __tun_detach(tfile, false);
> + else
> + ret = -EINVAL;
> +
> +unlock:
> + rtnl_unlock();
> + return ret;
> +}
> +
> static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
> unsigned long arg, int ifreq_len)
> {
> @@ -1543,7 +1582,7 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
> int vnet_hdr_sz;
> int ret;
>
> - if (cmd == TUNSETIFF || _IOC_TYPE(cmd) == 0x89) {
> + if (cmd == TUNSETIFF || cmd == TUNSETQUEUE || _IOC_TYPE(cmd) == 0x89) {
> if (copy_from_user(&ifr, argp, ifreq_len))
> return -EFAULT;
> } else {
> @@ -1554,9 +1593,10 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
> * This is needed because we never checked for invalid flags on
> * TUNSETIFF. */
> return put_user(IFF_TUN | IFF_TAP | IFF_NO_PI | IFF_ONE_QUEUE |
> - IFF_VNET_HDR,
> + IFF_VNET_HDR | IFF_MULTI_QUEUE,
> (unsigned int __user*)argp);
> - }
> + } else if (cmd == TUNSETQUEUE)
> + return tun_set_queue(file, &ifr);
>
> ret = 0;
> rtnl_lock();
> diff --git a/include/uapi/linux/if_tun.h b/include/uapi/linux/if_tun.h
> index 8ef3a87..958497a 100644
> --- a/include/uapi/linux/if_tun.h
> +++ b/include/uapi/linux/if_tun.h
> @@ -54,6 +54,7 @@
> #define TUNDETACHFILTER _IOW('T', 214, struct sock_fprog)
> #define TUNGETVNETHDRSZ _IOR('T', 215, int)
> #define TUNSETVNETHDRSZ _IOW('T', 216, int)
> +#define TUNSETQUEUE _IOW('T', 217, int)
>
> /* TUNSETIFF ifr flags */
> #define IFF_TUN 0x0001
> @@ -63,6 +64,8 @@
> #define IFF_VNET_HDR 0x4000
> #define IFF_TUN_EXCL 0x8000
> #define IFF_MULTI_QUEUE 0x0100
> +#define IFF_ATTACH_QUEUE 0x0200
> +#define IFF_DETACH_QUEUE 0x0400
>
> /* Features for GSO (TUNSETOFFLOAD). */
> #define TUN_F_CSUM 0x01 /* You can hand me unchecksummed packets. */
> --
> 1.7.1


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