[PATCH v7 37/46] tun: move internal flag defines out of uapi

Michael S. Tsirkin
2014-11-30T15:14:50Z

TUN_ flags are internal and never exposed
to userspace. Any application using it is almost
certainly buggy.

Move them out to tun.c.

Note: we remove these completely in follow-up patches,
this code movement is split out for ease of review.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
include/uapi/linux/if_tun.h | 16 ++--------
drivers/net/tun.c | 72 +++++++++++++--------------------------------
2 files changed, 24 insertions(+), 64 deletions(-)

diff --git a/include/uapi/linux/if_tun.h b/include/uapi/linux/if_tun.h
index e9502dd..277a260 100644
--- a/include/uapi/linux/if_tun.h
+++ b/include/uapi/linux/if_tun.h
@@ -22,21 +22,11 @@

/* Read queue size */
#define TUN_READQ_SIZE 500
-
-/* TUN device flags */
-#define TUN_TUN_DEV 0x0001
-#define TUN_TAP_DEV 0x0002
+/* TUN device type flags: deprecated. Use IFF_TUN/IFF_TAP instead. */
+#define TUN_TUN_DEV IFF_TUN
+#define TUN_TAP_DEV IFF_TAP
#define TUN_TYPE_MASK 0x000f

-#define TUN_FASYNC 0x0010
-#define TUN_NOCHECKSUM 0x0020
-#define TUN_NO_PI 0x0040
-/* This flag has no real effect */
-#define TUN_ONE_QUEUE 0x0080
-#define TUN_PERSIST 0x0100
-#define TUN_VNET_HDR 0x0200
-#define TUN_TAP_MQ 0x0400
-
/* Ioctl defines */
#define TUNSETNOCSUM _IOW('T', 200, int)
#define TUNSETDEBUG _IOW('T', 201, int)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 9dd3746..b4e4ca0 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -103,6 +103,21 @@ do { \
} while (0)
#endif

+/* TUN device flags */
+
+/* IFF_ATTACH_QUEUE is never stored in device flags,
+ * overload it to mean fasync when stored there.
+ */
+#define TUN_FASYNC IFF_ATTACH_QUEUE
+#define TUN_NO_PI IFF_NO_PI
+/* This flag has no real effect */
+#define TUN_ONE_QUEUE IFF_ONE_QUEUE
+#define TUN_PERSIST IFF_PERSIST
+#define TUN_VNET_HDR IFF_VNET_HDR
+#define TUN_TAP_MQ IFF_MULTI_QUEUE
+
+#define TUN_FEATURES (IFF_NO_PI | IFF_ONE_QUEUE | IFF_VNET_HDR | \
+ IFF_MULTI_QUEUE)
#define GOODCOPY_LEN 128

#define FLT_EXACT_COUNT 8
@@ -1521,32 +1536,7 @@ static struct proto tun_proto = {

static int tun_flags(struct tun_struct *tun)
{
- int flags = 0;
-
- if (tun->flags & TUN_TUN_DEV)
- flags |= IFF_TUN;
- else
- flags |= IFF_TAP;
-
- if (tun->flags & TUN_NO_PI)
- flags |= IFF_NO_PI;
-
- /* This flag has no real effect. We track the value for backwards
- * compatibility.
- */
- if (tun->flags & TUN_ONE_QUEUE)
- flags |= IFF_ONE_QUEUE;
-
- if (tun->flags & TUN_VNET_HDR)
- flags |= IFF_VNET_HDR;
-
- if (tun->flags & TUN_TAP_MQ)
- flags |= IFF_MULTI_QUEUE;
-
- if (tun->flags & TUN_PERSIST)
- flags |= IFF_PERSIST;
-
- return flags;
+ return tun->flags & (TUN_FEATURES | IFF_PERSIST | IFF_TUN | IFF_TAP);
}

static ssize_t tun_show_flags(struct device *dev, struct device_attribute *attr,
@@ -1706,28 +1696,8 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)

tun_debug(KERN_INFO, tun, "tun_set_iff\n");

- if (ifr->ifr_flags & IFF_NO_PI)
- tun->flags |= TUN_NO_PI;
- else
- tun->flags &= ~TUN_NO_PI;
-
- /* This flag has no real effect. We track the value for backwards
- * compatibility.
- */
- if (ifr->ifr_flags & IFF_ONE_QUEUE)
- tun->flags |= TUN_ONE_QUEUE;
- else
- tun->flags &= ~TUN_ONE_QUEUE;
-
- if (ifr->ifr_flags & IFF_VNET_HDR)
- tun->flags |= TUN_VNET_HDR;
- else
- tun->flags &= ~TUN_VNET_HDR;
-
- if (ifr->ifr_flags & IFF_MULTI_QUEUE)
- tun->flags |= TUN_TAP_MQ;
- else
- tun->flags &= ~TUN_TAP_MQ;
+ tun->flags = (tun->flags & ~TUN_FEATURES) |
+ (ifr->ifr_flags & TUN_FEATURES);

/* Make sure persistent devices do not get stuck in
* xoff state.
@@ -1890,9 +1860,9 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
if (cmd == TUNGETFEATURES) {
/* Currently this just means: "what IFF flags are valid?".
* 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_MULTI_QUEUE,
+ * TUNSETIFF.
+ */
+ return put_user(IFF_TUN | IFF_TAP | TUN_FEATURES,
(unsigned int __user*)argp);
} else if (cmd == TUNSETQUEUE)
return tun_set_queue(file, &ifr);
--
MST