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Commit 306da4e6 authored by Jesper Dangaard Brouer's avatar Jesper Dangaard Brouer Committed by David S. Miller
Browse files

samples/bpf: xdp_redirect load XDP dummy prog on TX device 



For supporting XDP_REDIRECT, a device driver must (obviously)
implement the "TX" function ndo_xdp_xmit().  An additional requirement
is you cannot TX out a device, unless it also have a xdp bpf program
attached. This dependency is caused by the driver code need to setup
XDP resources before it can ndo_xdp_xmit.

Update bpf samples xdp_redirect and xdp_redirect_map to automatically
attach a dummy XDP program to the configured ifindex_out device.  Use
the XDP flag XDP_FLAGS_UPDATE_IF_NOEXIST on the dummy load, to avoid
overriding an existing XDP prog on the device.

Signed-off-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 59a30896

samples/bpf/xdp_redirect_kern.c

+10 −1
Original line number Diff line number Diff line
@@ -26,6 +26,9 @@ struct bpf_map_def SEC("maps") tx_port = { 
	.max_entries = 1,

};



/* Count RX packets, as XDP bpf_prog doesn't get direct TX-success

 * feedback.  Redirect TX errors can be caught via a tracepoint.

 */

struct bpf_map_def SEC("maps") rxcnt = {

	.type = BPF_MAP_TYPE_PERCPU_ARRAY,

	.key_size = sizeof(u32),
@@ -33,7 +36,6 @@ struct bpf_map_def SEC("maps") rxcnt = { 
	.max_entries = 1,

};





static void swap_src_dst_mac(void *data)

{

	unsigned short *p = data;
@@ -78,4 +80,11 @@ int xdp_redirect_prog(struct xdp_md *ctx) 
	return bpf_redirect(*ifindex, 0);

}



/* Redirect require an XDP bpf_prog loaded on the TX device */

SEC("xdp_redirect_dummy")

int xdp_redirect_dummy(struct xdp_md *ctx)

{

	return XDP_PASS;

}



char _license[] SEC("license") = "GPL";

samples/bpf/xdp_redirect_map_kern.c

+10 −1
Original line number Diff line number Diff line
@@ -26,6 +26,9 @@ struct bpf_map_def SEC("maps") tx_port = { 
	.max_entries = 100,

};



/* Count RX packets, as XDP bpf_prog doesn't get direct TX-success

 * feedback.  Redirect TX errors can be caught via a tracepoint.

 */

struct bpf_map_def SEC("maps") rxcnt = {

	.type = BPF_MAP_TYPE_PERCPU_ARRAY,

	.key_size = sizeof(u32),
@@ -33,7 +36,6 @@ struct bpf_map_def SEC("maps") rxcnt = { 
	.max_entries = 1,

};





static void swap_src_dst_mac(void *data)

{

	unsigned short *p = data;
@@ -80,4 +82,11 @@ int xdp_redirect_map_prog(struct xdp_md *ctx) 
	return bpf_redirect_map(&tx_port, vport, 0);

}



/* Redirect require an XDP bpf_prog loaded on the TX device */

SEC("xdp_redirect_dummy")

int xdp_redirect_dummy(struct xdp_md *ctx)

{

	return XDP_PASS;

}



char _license[] SEC("license") = "GPL";

samples/bpf/xdp_redirect_map_user.c

+15 −7
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include <signal.h>

#include <stdio.h>

#include <stdlib.h>

#include <stdbool.h>

#include <string.h>

#include <unistd.h>

#include <libgen.h>
@@ -26,17 +27,18 @@ 


static int ifindex_in;

static int ifindex_out;

static bool ifindex_out_xdp_dummy_attached = true;



static __u32 xdp_flags;



static void int_exit(int sig)

{

	set_link_xdp_fd(ifindex_in, -1, xdp_flags);

	if (ifindex_out_xdp_dummy_attached)

		set_link_xdp_fd(ifindex_out, -1, xdp_flags);

	exit(0);

}



/* simple per-protocol drop counter

 */

static void poll_stats(int interval, int ifindex)

{

	unsigned int nr_cpus = bpf_num_possible_cpus();
@@ -70,7 +72,6 @@ static void usage(const char *prog) 
		prog);

}





int main(int argc, char **argv)

{

	const char *optstr = "SN";
@@ -112,14 +113,21 @@ int main(int argc, char **argv) 
		return 1;

	}



	signal(SIGINT, int_exit);

	signal(SIGTERM, int_exit);



	if (set_link_xdp_fd(ifindex_in, prog_fd[0], xdp_flags) < 0) {

		printf("link set xdp fd failed\n");

		printf("ERROR: link set xdp fd failed on %d\n", ifindex_in);

		return 1;

	}



	/* Loading dummy XDP prog on out-device */

	if (set_link_xdp_fd(ifindex_out, prog_fd[1],

			    (xdp_flags | XDP_FLAGS_UPDATE_IF_NOEXIST)) < 0) {

		printf("WARN: link set xdp fd failed on %d\n", ifindex_out);

		ifindex_out_xdp_dummy_attached = false;

	}



	signal(SIGINT, int_exit);

	signal(SIGTERM, int_exit);



	printf("map[0] (vports) = %i, map[1] (map) = %i, map[2] (count) = %i\n",

		map_fd[0], map_fd[1], map_fd[2]);

samples/bpf/xdp_redirect_user.c

+15 −6
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include <signal.h>

#include <stdio.h>

#include <stdlib.h>

#include <stdbool.h>

#include <string.h>

#include <unistd.h>

#include <libgen.h>
@@ -26,17 +27,18 @@ 


static int ifindex_in;

static int ifindex_out;

static bool ifindex_out_xdp_dummy_attached = true;



static __u32 xdp_flags;



static void int_exit(int sig)

{

	set_link_xdp_fd(ifindex_in, -1, xdp_flags);

	if (ifindex_out_xdp_dummy_attached)

		set_link_xdp_fd(ifindex_out, -1, xdp_flags);

	exit(0);

}



/* simple per-protocol drop counter

 */

static void poll_stats(int interval, int ifindex)

{

	unsigned int nr_cpus = bpf_num_possible_cpus();
@@ -112,14 +114,21 @@ int main(int argc, char **argv) 
		return 1;

	}



	signal(SIGINT, int_exit);

	signal(SIGTERM, int_exit);



	if (set_link_xdp_fd(ifindex_in, prog_fd[0], xdp_flags) < 0) {

		printf("link set xdp fd failed\n");

		printf("ERROR: link set xdp fd failed on %d\n", ifindex_in);

		return 1;

	}



	/* Loading dummy XDP prog on out-device */

	if (set_link_xdp_fd(ifindex_out, prog_fd[1],

			    (xdp_flags | XDP_FLAGS_UPDATE_IF_NOEXIST)) < 0) {

		printf("WARN: link set xdp fd failed on %d\n", ifindex_out);

		ifindex_out_xdp_dummy_attached = false;

	}



	signal(SIGINT, int_exit);

	signal(SIGTERM, int_exit);



	/* bpf redirect port */

	ret = bpf_map_update_elem(map_fd[0], &key, &ifindex_out, 0);

	if (ret) {