This adds support for a bpf_redirect helper function to the XDP
infrastructure. For now this only supports redirecting to the egress
path of a port.
In order to support drivers handling a xdp_buff natively this patches
uses a new ndo operation ndo_xdp_xmit() that takes pushes a xdp_buff
to the specified device.
If the program specifies either (a) an unknown device or (b) a device
that does not support the operation a BPF warning is thrown and the
XDP_ABORTED error code is returned.
Signed-off-by: John Fastabend <john.fastab...@gmail.com>
Acked-by: Daniel Borkmann <dan...@iogearbox.net>
---
include/linux/filter.h | 4 +++
include/linux/netdevice.h | 6 +++++
include/uapi/linux/bpf.h | 1 +
net/core/filter.c | 53 +++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 64 insertions(+)
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 1fa26dc..d0a1279 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -667,7 +667,11 @@ int sk_get_filter(struct sock *sk, struct sock_filter
__user *filter,
struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,
const struct bpf_insn *patch, u32 len);
+
+int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp);
+
void bpf_warn_invalid_xdp_action(u32 act);
+void bpf_warn_invalid_xdp_redirect(u32 ifindex);
#ifdef CONFIG_BPF_JIT
extern int bpf_jit_enable;
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 85f01d6..49e8c12 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -66,6 +66,7 @@
/* UDP Tunnel offloads */
struct udp_tunnel_info;
struct bpf_prog;
+struct xdp_buff;
void netdev_set_default_ethtool_ops(struct net_device *dev,
const struct ethtool_ops *ops);
@@ -1138,6 +1139,9 @@ struct xfrmdev_ops {
* int (*ndo_xdp)(struct net_device *dev, struct netdev_xdp *xdp);
* This function is used to set or query state related to XDP on the
* netdevice. See definition of enum xdp_netdev_command for details.
+ * int (*ndo_xdp_xmit)(struct net_device *dev, struct xdp_buff *xdp);
+ * This function is used to submit a XDP packet for transmit on a
+ * netdevice.
*
*/
struct net_device_ops {
@@ -1323,6 +1327,8 @@ struct net_device_ops {
int needed_headroom);
int (*ndo_xdp)(struct net_device *dev,
struct netdev_xdp *xdp);
+ int (*ndo_xdp_xmit)(struct net_device *dev,
+ struct xdp_buff *xdp);
};
/**
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index f94b48b..e1f3827 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -689,6 +689,7 @@ enum xdp_action {
XDP_DROP,
XDP_PASS,
XDP_TX,
+ XDP_REDIRECT,
};
/* user accessible metadata for XDP packet hook
diff --git a/net/core/filter.c b/net/core/filter.c
index b39c869..5c9fe3e 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2298,6 +2298,51 @@ static int bpf_skb_trim_rcsum(struct sk_buff *skb,
unsigned int new_len)
.arg2_type = ARG_ANYTHING,
};
+static int __bpf_tx_xdp(struct net_device *dev, struct xdp_buff *xdp)
+{
+ if (dev->netdev_ops->ndo_xdp_xmit) {
+ dev->netdev_ops->ndo_xdp_xmit(dev, xdp);
+ return 0;
+ }
+ bpf_warn_invalid_xdp_redirect(dev->ifindex);
+ return -EOPNOTSUPP;
+}
+
+int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp)
+{
+ struct redirect_info *ri = this_cpu_ptr(&redirect_info);
+
+ dev = dev_get_by_index_rcu(dev_net(dev), ri->ifindex);
+ ri->ifindex = 0;
+ if (unlikely(!dev)) {
+ bpf_warn_invalid_xdp_redirect(ri->ifindex);
+ return -EINVAL;
+ }
+
+ return __bpf_tx_xdp(dev, xdp);
+}
+EXPORT_SYMBOL_GPL(xdp_do_redirect);
+
+BPF_CALL_2(bpf_xdp_redirect, u32, ifindex, u64, flags)
+{
+ struct redirect_info *ri = this_cpu_ptr(&redirect_info);
+
+ if (unlikely(flags))
+ return XDP_ABORTED;
+
+ ri->ifindex = ifindex;
+ ri->flags = flags;
+ return XDP_REDIRECT;
+}
+
+static const struct bpf_func_proto bpf_xdp_redirect_proto = {
+ .func = bpf_xdp_redirect,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_ANYTHING,
+ .arg2_type = ARG_ANYTHING,
+};
+
bool bpf_helper_changes_pkt_data(void *func)
{
if (func == bpf_skb_vlan_push ||
@@ -2790,6 +2835,8 @@ static unsigned long bpf_xdp_copy(void *dst_buff, const
void *src_buff,
return &bpf_get_smp_processor_id_proto;
case BPF_FUNC_xdp_adjust_head:
return &bpf_xdp_adjust_head_proto;
+ case BPF_FUNC_redirect:
+ return &bpf_xdp_redirect_proto;
default:
return bpf_base_func_proto(func_id);
}
@@ -3110,6 +3157,12 @@ void bpf_warn_invalid_xdp_action(u32 act)
}
EXPORT_SYMBOL_GPL(bpf_warn_invalid_xdp_action);
+void bpf_warn_invalid_xdp_redirect(u32 ifindex)
+{
+ WARN_ONCE(1, "Illegal XDP redirect to unsupported device
ifindex(%i)\n", ifindex);
+}
+EXPORT_SYMBOL_GPL(bpf_warn_invalid_xdp_redirect);
+
static u32 bpf_convert_ctx_access(enum bpf_access_type type,
const struct bpf_insn *si,
struct bpf_insn *insn_buf,
