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ipip,ip_tunnel,sit: Add FOU support for externally controlled ipip devices

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Today ipip devices in collect-metadata mode don't allow for sending FOU
or GUE encapsulated packets. This patch lifts the restriction by adding
a struct ip_tunnel_encap to the tunnel metadata.

On the egress path, the members of this struct can be set by the
bpf_skb_set_fou_encap kfunc via a BPF tc-hook. Instead of dropping packets
wishing to use additional UDP encapsulation, ip_md_tunnel_xmit now
evaluates the contents of this struct and adds the corresponding FOU or
GUE header. Furthermore, it is making sure that additional header bytes
are taken into account for PMTU discovery.

On the ingress path, an ipip device in collect-metadata mode will fill this
struct and a BPF tc-hook can obtain the information via a call to the
bpf_skb_get_fou_encap kfunc.

The minor change to ip_tunnel_encap, which now takes a pointer to
struct ip_tunnel_encap instead of struct ip_tunnel, allows us to control
FOU encap type and parameters on a per packet-level.

Signed-off-by: Christian Ehrig <cehrig@cloudflare.com>
Link: https://lore.kernel.org/r/cfea47de655d0f870248abf725932f851b53960a.1680874078.git.cehrig@cloudflare.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Christian Ehrig 2023-04-07 15:38:53 +02:00 committed by Alexei Starovoitov
parent ed17aa92dc
commit ac931d4cde
4 changed files with 37 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
include/net/ip_tunnels.h
View File

@ -57,6 +57,13 @@ struct ip_tunnel_key {
__u8 flow_flags;
};
struct ip_tunnel_encap {
u16 type;
u16 flags;
__be16 sport;
__be16 dport;
};
/* Flags for ip_tunnel_info mode. */
#define IP_TUNNEL_INFO_TX 0x01 /* represents tx tunnel parameters */
#define IP_TUNNEL_INFO_IPV6 0x02 /* key contains IPv6 addresses */
@ -66,9 +73,9 @@ struct ip_tunnel_key {
#define IP_TUNNEL_OPTS_MAX \
GENMASK((sizeof_field(struct ip_tunnel_info, \
options_len) * BITS_PER_BYTE) - 1, 0)
struct ip_tunnel_info {
struct ip_tunnel_key key;
struct ip_tunnel_encap encap;
#ifdef CONFIG_DST_CACHE
struct dst_cache dst_cache;
#endif
@ -86,13 +93,6 @@ struct ip_tunnel_6rd_parm {
};
#endif
struct ip_tunnel_encap {
u16 type;
u16 flags;
__be16 sport;
__be16 dport;
};
struct ip_tunnel_prl_entry {
struct ip_tunnel_prl_entry __rcu *next;
__be32 addr;
@ -293,6 +293,7 @@ struct ip_tunnel *ip_tunnel_lookup(struct ip_tunnel_net *itn,
__be32 remote, __be32 local,
__be32 key);
void ip_tunnel_md_udp_encap(struct sk_buff *skb, struct ip_tunnel_info *info);
int ip_tunnel_rcv(struct ip_tunnel *tunnel, struct sk_buff *skb,
const struct tnl_ptk_info *tpi, struct metadata_dst *tun_dst,
bool log_ecn_error);
@ -371,22 +372,23 @@ static inline int ip_encap_hlen(struct ip_tunnel_encap *e)
return hlen;
}
static inline int ip_tunnel_encap(struct sk_buff *skb, struct ip_tunnel *t,
static inline int ip_tunnel_encap(struct sk_buff *skb,
struct ip_tunnel_encap *e,
u8 *protocol, struct flowi4 *fl4)
{
const struct ip_tunnel_encap_ops *ops;
int ret = -EINVAL;
if (t->encap.type == TUNNEL_ENCAP_NONE)
if (e->type == TUNNEL_ENCAP_NONE)
return 0;
if (t->encap.type >= MAX_IPTUN_ENCAP_OPS)
if (e->type >= MAX_IPTUN_ENCAP_OPS)
return -EINVAL;
rcu_read_lock();
ops = rcu_dereference(iptun_encaps[t->encap.type]);
ops = rcu_dereference(iptun_encaps[e->type]);
if (likely(ops && ops->build_header))
ret = ops->build_header(skb, &t->encap, protocol, fl4);
ret = ops->build_header(skb, e, protocol, fl4);
rcu_read_unlock();
return ret;

22
net/ipv4/ip_tunnel.c
View File

@ -359,6 +359,20 @@ err_dev_set_mtu:
return ERR_PTR(err);
}
void ip_tunnel_md_udp_encap(struct sk_buff *skb, struct ip_tunnel_info *info)
{
const struct iphdr *iph = ip_hdr(skb);
const struct udphdr *udph;
if (iph->protocol != IPPROTO_UDP)
return;
udph = (struct udphdr *)((__u8 *)iph + (iph->ihl << 2));
info->encap.sport = udph->source;
info->encap.dport = udph->dest;
}
EXPORT_SYMBOL(ip_tunnel_md_udp_encap);
int ip_tunnel_rcv(struct ip_tunnel *tunnel, struct sk_buff *skb,
const struct tnl_ptk_info *tpi, struct metadata_dst *tun_dst,
bool log_ecn_error)
@ -572,7 +586,11 @@ void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
tunnel_id_to_key32(key->tun_id), RT_TOS(tos),
dev_net(dev), 0, skb->mark, skb_get_hash(skb),
key->flow_flags);
if (tunnel->encap.type != TUNNEL_ENCAP_NONE)
if (!tunnel_hlen)
tunnel_hlen = ip_encap_hlen(&tun_info->encap);
if (ip_tunnel_encap(skb, &tun_info->encap, &proto, &fl4) < 0)
goto tx_error;
use_cache = ip_tunnel_dst_cache_usable(skb, tun_info);
@ -732,7 +750,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
dev_net(dev), tunnel->parms.link,
tunnel->fwmark, skb_get_hash(skb), 0);
if (ip_tunnel_encap(skb, tunnel, &protocol, &fl4) < 0)
if (ip_tunnel_encap(skb, &tunnel->encap, &protocol, &fl4) < 0)
goto tx_error;
if (connected && md) {

1
net/ipv4/ipip.c
View File

@ -241,6 +241,7 @@ static int ipip_tunnel_rcv(struct sk_buff *skb, u8 ipproto)
tun_dst = ip_tun_rx_dst(skb, 0, 0, 0);
if (!tun_dst)
return 0;
ip_tunnel_md_udp_encap(skb, &tun_dst->u.tun_info);
}
skb_reset_mac_header(skb);

2
net/ipv6/sit.c
View File

@ -1024,7 +1024,7 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
ttl = iph6->hop_limit;
tos = INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
if (ip_tunnel_encap(skb, tunnel, &protocol, &fl4) < 0) {
if (ip_tunnel_encap(skb, &tunnel->encap, &protocol, &fl4) < 0) {
ip_rt_put(rt);
goto tx_error;
}