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Date: Mon, 19 Aug 2013 13:29:37 -0700
From: Valas Valancius <vytautas.valancius@...il.com>
To: Valas Valancius <valas@...gle.com>,
"David S. Miller" <davem@...emloft.net>
Cc: Eric Dumazet <edumazet@...gle.com>,
Maciej Żenczykowski <maze@...gle.com>,
netdev@...r.kernel.org
Subject: [PATCH] Passing sk_buff metadata information to user space in TUNTAP driver.
From: Valas Valancius <valas@...gle.com>
This patch introduces an optional metadata header to TUNTAP driver to pass
sk_buff information to user space. The patch currently enables passing
of skb->mark field and allows for easy expansion to add more sk_buff
fields later.
Tested: Compiled, booted. Process 1: openend TAP interface, enabled metadata
header on that interface. Process 2: opened a socket, set fwmark with SO_MARK
sock option, send packets, observed mark to propagate in Process 1.
Change-Id: I5d00522e9c4d9c1b57b4f4ac55c419a85de35dae
---
drivers/net/tun.c | 64 ++++++++++++++++++++++++++++++++++++++++++++-
include/uapi/linux/if_tun.h | 7 +++++
2 files changed, 70 insertions(+), 1 deletion(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 978d865..f997d59 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -103,6 +103,15 @@ do { \
#define GOODCOPY_LEN 128
+/* Metadata header structure. */
+struct tun_meta_header {
+ /* struct sk_buff.mark */
+ int mark;
+};
+
+#define TUN_META_HDR_SZ sizeof(struct tun_meta_header)
+#define TUN_META_MARK_OFFSET offsetof(struct tun_meta_header, mark)
+
#define FLT_EXACT_COUNT 8
struct tap_filter {
unsigned int count; /* Number of addrs. Zero means disabled */
@@ -1227,6 +1236,20 @@ static ssize_t tun_put_user(struct tun_struct *tun,
total += tun->vnet_hdr_sz;
}
+ if (tun->flags & TUN_META_HDR) {
+ struct tun_meta_header meta = { 0 };
+ len -= TUN_META_HDR_SZ;
+ if (len < 0)
+ return -EINVAL;
+
+ meta.mark = skb->mark;
+
+ if (unlikely(memcpy_toiovecend(iv, (void *)&meta, total,
+ sizeof(meta))))
+ return -EFAULT;
+ total += TUN_META_HDR_SZ;
+ }
+
if (!vlan_tx_tag_present(skb)) {
len = min_t(int, skb->len, len);
} else {
@@ -1487,6 +1510,9 @@ static int tun_flags(struct tun_struct *tun)
if (tun->flags & TUN_PERSIST)
flags |= IFF_PERSIST;
+ if (tun->flags & TUN_META_HDR)
+ flags |= IFF_META_HDR;
+
return flags;
}
@@ -1666,6 +1692,11 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
else
tun->flags &= ~TUN_TAP_MQ;
+ if (ifr->ifr_flags & IFF_META_HDR)
+ tun->flags |= TUN_META_HDR;
+ else
+ tun->flags &= ~TUN_META_HDR;
+
/* Make sure persistent devices do not get stuck in
* xoff state.
*/
@@ -1815,6 +1846,8 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
kgid_t group;
int sndbuf;
int vnet_hdr_sz;
+ int tun_meta_param;
+ int tun_meta_value;
int ret;
if (cmd == TUNSETIFF || cmd == TUNSETQUEUE || _IOC_TYPE(cmd) == 0x89) {
@@ -1828,7 +1861,7 @@ 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_MULTI_QUEUE,
+ IFF_VNET_HDR | IFF_MULTI_QUEUE | IFF_META_HDR,
(unsigned int __user*)argp);
} else if (cmd == TUNSETQUEUE)
return tun_set_queue(file, &ifr);
@@ -1996,6 +2029,35 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
tun->vnet_hdr_sz = vnet_hdr_sz;
break;
+ case TUNGETMETAPARAM:
+ if (copy_from_user(&tun_meta_param, argp,
+ sizeof(tun_meta_param))) {
+ ret = -EFAULT;
+ break;
+ }
+
+ ret = 0;
+ switch (tun_meta_param) {
+ case TUN_GET_META_HDR_SZ:
+ tun_meta_value = TUN_META_HDR_SZ;
+ break;
+
+ case TUN_GET_META_MARK_OFFSET:
+ tun_meta_value = TUN_META_MARK_OFFSET;
+ break;
+
+ default:
+ ret = -EINVAL;
+ break;
+ }
+
+ if (!ret)
+ if (copy_to_user(argp, &tun_meta_value,
+ sizeof(tun_meta_value)))
+ ret = -EFAULT;
+ break;
+
+
case TUNATTACHFILTER:
/* Can be set only for TAPs */
ret = -EINVAL;
diff --git a/include/uapi/linux/if_tun.h b/include/uapi/linux/if_tun.h
index 1870ee2..26e6c9e 100644
--- a/include/uapi/linux/if_tun.h
+++ b/include/uapi/linux/if_tun.h
@@ -36,6 +36,7 @@
#define TUN_PERSIST 0x0100
#define TUN_VNET_HDR 0x0200
#define TUN_TAP_MQ 0x0400
+#define TUN_META_HDR 0x0800
/* Ioctl defines */
#define TUNSETNOCSUM _IOW('T', 200, int)
@@ -56,10 +57,12 @@
#define TUNGETVNETHDRSZ _IOR('T', 215, int)
#define TUNSETVNETHDRSZ _IOW('T', 216, int)
#define TUNSETQUEUE _IOW('T', 217, int)
+#define TUNGETMETAPARAM _IOR('T', 218, int)
/* TUNSETIFF ifr flags */
#define IFF_TUN 0x0001
#define IFF_TAP 0x0002
+#define IFF_META_HDR 0x0004
#define IFF_NO_PI 0x1000
/* This flag has no real effect */
#define IFF_ONE_QUEUE 0x2000
@@ -103,4 +106,8 @@ struct tun_filter {
__u8 addr[0][ETH_ALEN];
};
+/* TUNGETMETAPARAM metadata header request types. */
+#define TUN_GET_META_HDR_SZ 0
+#define TUN_GET_META_MARK_OFFSET 1
+
#endif /* _UAPI__IF_TUN_H */
--
1.8.3
--
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