* [PATCH bpf-next 1/3] ipip,ip_tunnel,sit: Add FOU support for externally controlled ipip devices
2023-04-01 20:33 [PATCH bpf-next 0/3] Add FOU support for externally controlled ipip devices Christian Ehrig
@ 2023-04-01 20:33 ` Christian Ehrig
2023-04-01 20:33 ` [PATCH bpf-next 2/3] bpf,fou: Add bpf_skb_{set,get}_fou_encap kfuncs Christian Ehrig
1 sibling, 0 replies; 5+ messages in thread
From: Christian Ehrig @ 2023-04-01 20:33 UTC (permalink / raw)
To: bpf
Cc: cehrig, David S. Miller, David Ahern, Eric Dumazet,
Jakub Kicinski, Paolo Abeni, netdev, linux-kernel
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>
---
include/net/ip_tunnels.h | 27 ++++++++++++++-------------
net/ipv4/ip_tunnel.c | 22 ++++++++++++++++++++--
net/ipv4/ipip.c | 1 +
net/ipv6/sit.c | 2 +-
4 files changed, 36 insertions(+), 16 deletions(-)
diff --git a/include/net/ip_tunnels.h b/include/net/ip_tunnels.h
index fca357679816..ce091a3c257f 100644
--- a/include/net/ip_tunnels.h
+++ b/include/net/ip_tunnels.h
@@ -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 +372,22 @@ 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;
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index de90b09dfe78..add437f710fc 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -359,6 +359,20 @@ static struct ip_tunnel *ip_tunnel_create(struct net *net,
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) {
diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index abea77759b7e..27b8f83c6ea2 100644
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -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);
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 70d81bba5093..063560e2cb1a 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -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;
}
--
2.39.2
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH bpf-next 2/3] bpf,fou: Add bpf_skb_{set,get}_fou_encap kfuncs
2023-04-01 20:33 [PATCH bpf-next 0/3] Add FOU support for externally controlled ipip devices Christian Ehrig
2023-04-01 20:33 ` [PATCH bpf-next 1/3] ipip,ip_tunnel,sit: " Christian Ehrig
@ 2023-04-01 20:33 ` Christian Ehrig
2023-04-01 20:51 ` kernel test robot
2023-04-01 20:51 ` kernel test robot
1 sibling, 2 replies; 5+ messages in thread
From: Christian Ehrig @ 2023-04-01 20:33 UTC (permalink / raw)
To: bpf
Cc: cehrig, David S. Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni, David Ahern, linux-kernel, netdev
Add two new kfuncs that allow a BPF tc-hook, installed on an ipip
device in collect-metadata mode, to control FOU encap parameters on a
per-packet level. The set of kfuncs is registered with the fou module.
The bpf_skb_set_fou_encap kfunc is supposed to be used in tandem and after
a successful call to the bpf_skb_set_tunnel_key bpf-helper. UDP source and
destination ports can be controlled by passing a struct bpf_fou_encap. A
source port of zero will auto-assign a source port. enum bpf_fou_encap_type
is used to specify if the egress path should FOU or GUE encap the packet.
On the ingress path bpf_skb_get_fou_encap can be used to read UDP source
and destination ports from the receiver's point of view and allows for
packet multiplexing across different destination ports within a single
BPF program and ipip device.
Signed-off-by: Christian Ehrig <cehrig@cloudflare.com>
---
include/net/fou.h | 2 +
net/ipv4/Makefile | 2 +-
net/ipv4/fou_bpf.c | 118 ++++++++++++++++++++++++++++++++++++++++++++
net/ipv4/fou_core.c | 5 ++
4 files changed, 126 insertions(+), 1 deletion(-)
create mode 100644 net/ipv4/fou_bpf.c
diff --git a/include/net/fou.h b/include/net/fou.h
index 80f56e275b08..824eb4b231fd 100644
--- a/include/net/fou.h
+++ b/include/net/fou.h
@@ -17,4 +17,6 @@ int __fou_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,
int __gue_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,
u8 *protocol, __be16 *sport, int type);
+int register_fou_bpf(void);
+
#endif
diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
index 880277c9fd07..b18ba8ef93ad 100644
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -26,7 +26,7 @@ obj-$(CONFIG_IP_MROUTE) += ipmr.o
obj-$(CONFIG_IP_MROUTE_COMMON) += ipmr_base.o
obj-$(CONFIG_NET_IPIP) += ipip.o
gre-y := gre_demux.o
-fou-y := fou_core.o fou_nl.o
+fou-y := fou_core.o fou_nl.o fou_bpf.o
obj-$(CONFIG_NET_FOU) += fou.o
obj-$(CONFIG_NET_IPGRE_DEMUX) += gre.o
obj-$(CONFIG_NET_IPGRE) += ip_gre.o
diff --git a/net/ipv4/fou_bpf.c b/net/ipv4/fou_bpf.c
new file mode 100644
index 000000000000..462298d87a2f
--- /dev/null
+++ b/net/ipv4/fou_bpf.c
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Unstable Fou Helpers for TC-BPF hook
+ *
+ * These are called from SCHED_CLS BPF programs. Note that it is
+ * allowed to break compatibility for these functions since the interface they
+ * are exposed through to BPF programs is explicitly unstable.
+ */
+
+#include <linux/bpf.h>
+#include <linux/btf_ids.h>
+
+#include <net/dst_metadata.h>
+
+struct bpf_fou_encap {
+ __be16 sport;
+ __be16 dport;
+};
+
+enum bpf_fou_encap_type {
+ FOU_BPF_ENCAP_FOU,
+ FOU_BPF_ENCAP_GUE,
+};
+
+__diag_push();
+__diag_ignore_all("-Wmissing-prototypes",
+ "Global functions as their definitions will be in BTF");
+
+/* bpf_skb_set_fou_encap - Set FOU encap parameters
+ *
+ * This function allows for using GUE or FOU encapsulation together with an
+ * ipip device in collect-metadata mode.
+ *
+ * It is meant to be used in BPF tc-hooks and after a call to the
+ * bpf_skb_set_tunnel_key helper, responsible for setting IP addresses.
+ *
+ * Parameters:
+ * @skb_ctx Pointer to ctx (__sk_buff) in TC program. Cannot be NULL
+ * @encap Pointer to a `struct bpf_fou_encap` storing UDP src and
+ * dst ports. If sport is set to 0 the kernel will auto-assign a
+ * port. This is similar to using `encap-sport auto`.
+ * Cannot be NULL
+ * @type Encapsulation type for the packet. Their definitions are
+ * specified in `enum bpf_fou_encap_type`
+ */
+__bpf_kfunc int bpf_skb_set_fou_encap(struct __sk_buff *skb_ctx,
+ struct bpf_fou_encap *encap, int type)
+{
+ struct sk_buff *skb = (struct sk_buff *)skb_ctx;
+ struct ip_tunnel_info *info = skb_tunnel_info(skb);
+
+ if (unlikely(!encap))
+ return -EINVAL;
+
+ if (unlikely(!info || !(info->mode & IP_TUNNEL_INFO_TX)))
+ return -EINVAL;
+
+ switch (type) {
+ case FOU_BPF_ENCAP_FOU:
+ info->encap.type = TUNNEL_ENCAP_FOU;
+ break;
+ case FOU_BPF_ENCAP_GUE:
+ info->encap.type = TUNNEL_ENCAP_GUE;
+ break;
+ default:
+ info->encap.type = TUNNEL_ENCAP_NONE;
+ }
+
+ if (info->key.tun_flags & TUNNEL_CSUM)
+ info->encap.flags |= TUNNEL_ENCAP_FLAG_CSUM;
+
+ info->encap.sport = encap->sport;
+ info->encap.dport = encap->dport;
+
+ return 0;
+}
+
+/* bpf_skb_get_fou_encap - Get FOU encap parameters
+ *
+ * This function allows for reading encap metadata from a packet received
+ * on an ipip device in collect-metadata mode.
+ *
+ * Parameters:
+ * @skb_ctx Pointer to ctx (__sk_buff) in TC program. Cannot be NULL
+ * @encap Pointer to a struct bpf_fou_encap storing UDP source and
+ * destination port. Cannot be NULL
+ */
+__bpf_kfunc int bpf_skb_get_fou_encap(struct __sk_buff *skb_ctx,
+ struct bpf_fou_encap *encap)
+{
+ struct sk_buff *skb = (struct sk_buff *)skb_ctx;
+ struct ip_tunnel_info *info = skb_tunnel_info(skb);
+
+ if (unlikely(!info))
+ return -EINVAL;
+
+ encap->sport = info->encap.sport;
+ encap->dport = info->encap.dport;
+
+ return 0;
+}
+
+__diag_pop()
+
+BTF_SET8_START(fou_kfunc_set)
+BTF_ID_FLAGS(func, bpf_skb_set_fou_encap)
+BTF_ID_FLAGS(func, bpf_skb_get_fou_encap)
+BTF_SET8_END(fou_kfunc_set)
+
+static const struct btf_kfunc_id_set fou_bpf_kfunc_set = {
+ .owner = THIS_MODULE,
+ .set = &fou_kfunc_set,
+};
+
+int register_fou_bpf(void)
+{
+ return register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS,
+ &fou_bpf_kfunc_set);
+}
diff --git a/net/ipv4/fou_core.c b/net/ipv4/fou_core.c
index cafec9b4eee0..0c41076e31ed 100644
--- a/net/ipv4/fou_core.c
+++ b/net/ipv4/fou_core.c
@@ -1236,10 +1236,15 @@ static int __init fou_init(void)
if (ret < 0)
goto unregister;
+ ret = register_fou_bpf();
+ if (ret < 0)
+ goto kfunc_failed;
+
ret = ip_tunnel_encap_add_fou_ops();
if (ret == 0)
return 0;
+kfunc_failed:
genl_unregister_family(&fou_nl_family);
unregister:
unregister_pernet_device(&fou_net_ops);
--
2.39.2
^ permalink raw reply related [flat|nested] 5+ messages in thread