mirrors
/
linux-stable
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
1
0
Fork 0
Code Issues Releases Wiki Activity

bpf: Drop MTU check when doing TC-BPF redirect to ingress 

The use-case for dropping the MTU check when TC-BPF does redirect to
ingress, is described by Eyal Birger in email[0]. The summary is the
ability to increase packet size (e.g. with IPv6 headers for NAT64) and
ingress redirect packet and let normal netstack fragment packet as needed.

[0] https://lore.kernel.org/netdev/CAHsH6Gug-hsLGHQ6N0wtixdOa85LDZ3HNRHVd0opR=19Qo4W4Q@mail.gmail.com/

V15:
 - missing static for function declaration

V9:
 - Make net_device "up" (IFF_UP) check explicit in skb_do_redirect

V4:
 - Keep net_device "up" (IFF_UP) check.
 - Adjustment to handle bpf_redirect_peer() helper

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/161287790971.790810.11785274340154740591.stgit@firesoul
This commit is contained in:
Jesper Dangaard Brouer 2021-02-09 14:38:29 +01:00 committed by Daniel Borkmann
parent 34b2021cc6
commit 5f7d57280c
3 changed files with 47 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
include/linux/netdevice.h
View File

@ -3931,14 +3931,42 @@ int xdp_umem_query(struct net_device *dev, u16 queue_id);
int __dev_forward_skb(struct net_device *dev, struct sk_buff *skb);
int dev_forward_skb(struct net_device *dev, struct sk_buff *skb);
int dev_forward_skb_nomtu(struct net_device *dev, struct sk_buff *skb);
bool is_skb_forwardable(const struct net_device *dev,
const struct sk_buff *skb);
static __always_inline bool __is_skb_forwardable(const struct net_device *dev,
const struct sk_buff *skb,
const bool check_mtu)
{
const u32 vlan_hdr_len = 4; /* VLAN_HLEN */
unsigned int len;
if (!(dev->flags & IFF_UP))
return false;
if (!check_mtu)
return true;
len = dev->mtu + dev->hard_header_len + vlan_hdr_len;
if (skb->len <= len)
return true;
/* if TSO is enabled, we don't care about the length as the packet
* could be forwarded without being segmented before
*/
if (skb_is_gso(skb))
return true;
return false;
}
static __always_inline int ____dev_forward_skb(struct net_device *dev,
struct sk_buff *skb)
struct sk_buff *skb,
const bool check_mtu)
{
if (skb_orphan_frags(skb, GFP_ATOMIC) ||
unlikely(!is_skb_forwardable(dev, skb))) {
unlikely(!__is_skb_forwardable(dev, skb, check_mtu))) {
atomic_long_inc(&dev->rx_dropped);
kfree_skb(skb);
return NET_RX_DROP;

32
net/core/dev.c
View File

@ -2194,28 +2194,14 @@ static inline void net_timestamp_set(struct sk_buff *skb)
bool is_skb_forwardable(const struct net_device *dev, const struct sk_buff *skb)
{
unsigned int len;
if (!(dev->flags & IFF_UP))
return false;
len = dev->mtu + dev->hard_header_len + VLAN_HLEN;
if (skb->len <= len)
return true;
/* if TSO is enabled, we don't care about the length as the packet
* could be forwarded without being segmented before
*/
if (skb_is_gso(skb))
return true;
return false;
return __is_skb_forwardable(dev, skb, true);
}
EXPORT_SYMBOL_GPL(is_skb_forwardable);
int __dev_forward_skb(struct net_device *dev, struct sk_buff *skb)
static int __dev_forward_skb2(struct net_device *dev, struct sk_buff *skb,
bool check_mtu)
{
int ret = ____dev_forward_skb(dev, skb);
int ret = ____dev_forward_skb(dev, skb, check_mtu);
if (likely(!ret)) {
skb->protocol = eth_type_trans(skb, dev);
@ -2224,6 +2210,11 @@ int __dev_forward_skb(struct net_device *dev, struct sk_buff *skb)
return ret;
}
int __dev_forward_skb(struct net_device *dev, struct sk_buff *skb)
{
return __dev_forward_skb2(dev, skb, true);
}
EXPORT_SYMBOL_GPL(__dev_forward_skb);
/**
@ -2250,6 +2241,11 @@ int dev_forward_skb(struct net_device *dev, struct sk_buff *skb)
}
EXPORT_SYMBOL_GPL(dev_forward_skb);
int dev_forward_skb_nomtu(struct net_device *dev, struct sk_buff *skb)
{
return __dev_forward_skb2(dev, skb, false) ?: netif_rx_internal(skb);
}
static inline int deliver_skb(struct sk_buff *skb,
struct packet_type *pt_prev,
struct net_device *orig_dev)

6
net/core/filter.c
View File

@ -2083,13 +2083,13 @@ static const struct bpf_func_proto bpf_csum_level_proto = {
static inline int __bpf_rx_skb(struct net_device *dev, struct sk_buff *skb)
{
return dev_forward_skb(dev, skb);
return dev_forward_skb_nomtu(dev, skb);
}
static inline int __bpf_rx_skb_no_mac(struct net_device *dev,
struct sk_buff *skb)
{
int ret = ____dev_forward_skb(dev, skb);
int ret = ____dev_forward_skb(dev, skb, false);
if (likely(!ret)) {
skb->dev = dev;
@ -2480,7 +2480,7 @@ int skb_do_redirect(struct sk_buff *skb)
goto out_drop;
dev = ops->ndo_get_peer_dev(dev);
if (unlikely(!dev ||
!is_skb_forwardable(dev, skb) ||
!(dev->flags & IFF_UP) ||
net_eq(net, dev_net(dev))))
goto out_drop;
skb->dev = dev;