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xdp: add bpf_redirect helper function

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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.fastabend@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
John Fastabend 2017-07-17 09:27:07 -07:00 committed by David S. Miller
parent d445516966
commit 814abfabef
4 changed files with 63 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

4
include/linux/filter.h
View file

@ -711,7 +711,11 @@ bool bpf_helper_changes_pkt_data(void *func);
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;

6
include/linux/netdevice.h
View file

@ -66,6 +66,7 @@ struct mpls_dev;
/* 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);
};
/**

1
include/uapi/linux/bpf.h
View file

@ -717,6 +717,7 @@ enum xdp_action {
XDP_DROP,
XDP_PASS,
XDP_TX,
XDP_REDIRECT,
};
/* user accessible metadata for XDP packet hook

52
net/core/filter.c
View file

@ -2412,6 +2412,51 @@ static const struct bpf_func_proto bpf_xdp_adjust_head_proto = {
.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 ||
@ -3011,6 +3056,8 @@ xdp_func_proto(enum bpf_func_id func_id)
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);
}
@ -3310,6 +3357,11 @@ 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);
}
static bool __is_valid_sock_ops_access(int off, int size)
{
if (off < 0 || off >= sizeof(struct bpf_sock_ops))