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Subject[net-next v5 6/7] tuntap: add ioctl to attach or detach a file form tuntap device
Date
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);
+ } 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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