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Message-ID: <e8843f32aa14baff398584e5b3a00d20994836b6.camel@infradead.org>
Date: Wed, 23 Jun 2021 14:52:30 +0100
From: David Woodhouse <dwmw2@...radead.org>
To: Jason Wang <jasowang@...hat.com>, netdev@...r.kernel.org
Cc: Eugenio Pérez <eperezma@...hat.com>
Subject: Re: [PATCH v2 1/4] net: tun: fix tun_xdp_one() for IFF_TUN mode
On Wed, 2021-06-23 at 11:45 +0800, Jason Wang wrote:
>
> As replied in previous version, it would be better if we can unify
> similar logic in tun_get_user().
So that ends up looking something like this (incremental).
Note the '/* XXX: frags && */' part in tun_skb_set_protocol(), because
the 'frags &&' was there in tun_get_user() and it wasn't obvious to me
whether I should be lifting that out as a separate argument to
tun_skb_set_protocol() or if there's a better way.
Either way, in my judgement this is less suitable for a stable fix and
more appropriate for a follow-on cleanup. But I don't feel that
strongly; I'm more than happy for you to overrule me on that.
Especially if you fix the above XXX part while you're at it :)
I tested this with vhost-net and !IFF_NO_PI, and TX works. RX is still
hosed on the vhost-net side, for the same reason that a bunch of test
cases were already listed in #if 0, but I'll address that in a separate
email. It's not part of *this* patch.
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1641,6 +1641,40 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
return NULL;
}
+static int tun_skb_set_protocol(struct tun_struct *tun, struct sk_buff *skb,
+ __be16 pi_proto)
+{
+ switch (tun->flags & TUN_TYPE_MASK) {
+ case IFF_TUN:
+ if (tun->flags & IFF_NO_PI) {
+ u8 ip_version = skb->len ? (skb->data[0] >> 4) : 0;
+
+ switch (ip_version) {
+ case 4:
+ pi_proto = htons(ETH_P_IP);
+ break;
+ case 6:
+ pi_proto = htons(ETH_P_IPV6);
+ break;
+ default:
+ return -EINVAL;
+ }
+ }
+
+ skb_reset_mac_header(skb);
+ skb->protocol = pi_proto;
+ skb->dev = tun->dev;
+ break;
+ case IFF_TAP:
+ if (/* XXX frags && */!pskb_may_pull(skb, ETH_HLEN))
+ return -ENOMEM;
+
+ skb->protocol = eth_type_trans(skb, tun->dev);
+ break;
+ }
+ return 0;
+}
+
/* Get packet from user space buffer */
static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
void *msg_control, struct iov_iter *from,
@@ -1784,37 +1818,9 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
return -EINVAL;
}
- switch (tun->flags & TUN_TYPE_MASK) {
- case IFF_TUN:
- if (tun->flags & IFF_NO_PI) {
- u8 ip_version = skb->len ? (skb->data[0] >> 4) : 0;
-
- switch (ip_version) {
- case 4:
- pi.proto = htons(ETH_P_IP);
- break;
- case 6:
- pi.proto = htons(ETH_P_IPV6);
- break;
- default:
- atomic_long_inc(&tun->dev->rx_dropped);
- kfree_skb(skb);
- return -EINVAL;
- }
- }
-
- skb_reset_mac_header(skb);
- skb->protocol = pi.proto;
- skb->dev = tun->dev;
- break;
- case IFF_TAP:
- if (frags && !pskb_may_pull(skb, ETH_HLEN)) {
- err = -ENOMEM;
- goto drop;
- }
- skb->protocol = eth_type_trans(skb, tun->dev);
- break;
- }
+ err = tun_skb_set_protocol(tun, skb, pi.proto);
+ if (err)
+ goto drop;
/* copy skb_ubuf_info for callback when skb has no error */
if (zerocopy) {
@@ -2334,8 +2340,10 @@ static int tun_xdp_one(struct tun_struct *tun,
struct virtio_net_hdr *gso = NULL;
struct bpf_prog *xdp_prog;
struct sk_buff *skb = NULL;
+ __be16 proto = 0;
u32 rxhash = 0, act;
int buflen = hdr->buflen;
+ int reservelen = xdp->data - xdp->data_hard_start;
int err = 0;
bool skb_xdp = false;
struct page *page;
@@ -2343,6 +2351,17 @@ static int tun_xdp_one(struct tun_struct *tun,
if (tun->flags & IFF_VNET_HDR)
gso = &hdr->gso;
+ if (!(tun->flags & IFF_NO_PI)) {
+ struct tun_pi *pi = xdp->data;
+ if (datasize < sizeof(*pi)) {
+ atomic_long_inc(&tun->rx_frame_errors);
+ return -EINVAL;
+ }
+ proto = pi->proto;
+ reservelen += sizeof(*pi);
+ datasize -= sizeof(*pi);
+ }
+
xdp_prog = rcu_dereference(tun->xdp_prog);
if (xdp_prog) {
if (gso && gso->gso_type) {
@@ -2388,8 +2407,8 @@ static int tun_xdp_one(struct tun_struct *tun,
goto out;
}
- skb_reserve(skb, xdp->data - xdp->data_hard_start);
- skb_put(skb, xdp->data_end - xdp->data);
+ skb_reserve(skb, reservelen);
+ skb_put(skb, datasize);
if (gso && virtio_net_hdr_to_skb(skb, gso, tun_is_little_endian(tun))) {
atomic_long_inc(&tun->rx_frame_errors);
@@ -2397,48 +2416,12 @@ static int tun_xdp_one(struct tun_struct *tun,
err = -EINVAL;
goto out;
}
- switch (tun->flags & TUN_TYPE_MASK) {
- case IFF_TUN:
- if (tun->flags & IFF_NO_PI) {
- u8 ip_version = skb->len ? (skb->data[0] >> 4) : 0;
- switch (ip_version) {
- case 4:
- skb->protocol = htons(ETH_P_IP);
- break;
- case 6:
- skb->protocol = htons(ETH_P_IPV6);
- break;
- default:
- atomic_long_inc(&tun->dev->rx_dropped);
- kfree_skb(skb);
- err = -EINVAL;
- goto out;
- }
- } else {
- struct tun_pi *pi = (struct tun_pi *)skb->data;
- if (!pskb_may_pull(skb, sizeof(*pi))) {
- atomic_long_inc(&tun->dev->rx_dropped);
- kfree_skb(skb);
- err = -ENOMEM;
- goto out;
- }
- skb_pull_inline(skb, sizeof(*pi));
- skb->protocol = pi->proto;
- }
-
- skb_reset_mac_header(skb);
- skb->dev = tun->dev;
- break;
- case IFF_TAP:
- if (!pskb_may_pull(skb, ETH_HLEN)) {
- atomic_long_inc(&tun->dev->rx_dropped);
- kfree_skb(skb);
- err = -ENOMEM;
- goto out;
- }
- skb->protocol = eth_type_trans(skb, tun->dev);
- break;
+ err = tun_skb_set_protocol(tun, skb, proto);
+ if (err) {
+ atomic_long_inc(&tun->dev->rx_dropped);
+ kfree_skb(skb);
+ goto out;
}
skb_reset_network_header(skb);
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