This patch add a xdp program on egress to show that we can modify
the packet on egress. In this sample we will set the pkt's src
mac to egress's mac address. The xdp_prog will be attached when
-X option supplied.
Signed-off-by: Hangbin Liu <liuhangbin@xxxxxxxxx>
---
v3:
a) modify the src mac address based on egress mac
v2:
a) use pkt counter instead of IP ttl modification on egress program
b) make the egress program selectable by option -X
---
samples/bpf/xdp_redirect_map_kern.c | 60 ++++++++++-
samples/bpf/xdp_redirect_map_user.c | 153 ++++++++++++++++++++--------
2 files changed, 168 insertions(+), 45 deletions(-)
diff --git a/samples/bpf/xdp_redirect_map_kern.c b/samples/bpf/xdp_redirect_map_kern.c
index 6489352ab7a4..6b2164722649 100644
--- a/samples/bpf/xdp_redirect_map_kern.c
+++ b/samples/bpf/xdp_redirect_map_kern.c
@@ -19,12 +19,22 @@
#include <linux/ipv6.h>
#include <bpf/bpf_helpers.h>
+/* The 2nd xdp prog on egress does not support skb mode, so we define two
+ * maps, tx_port_general and tx_port_native.
+ */
struct {
__uint(type, BPF_MAP_TYPE_DEVMAP);
__uint(key_size, sizeof(int));
__uint(value_size, sizeof(int));
__uint(max_entries, 100);
-} tx_port SEC(".maps");
+} tx_port_general SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_DEVMAP);
+ __uint(key_size, sizeof(int));
+ __uint(value_size, sizeof(struct bpf_devmap_val));
+ __uint(max_entries, 100);
+} tx_port_native SEC(".maps");
/* Count RX packets, as XDP bpf_prog doesn't get direct TX-success
* feedback. Redirect TX errors can be caught via a tracepoint.
@@ -36,6 +46,14 @@ struct {
__uint(max_entries, 1);
} rxcnt SEC(".maps");
+/* map to stroe egress interface mac address */
+struct {
+ __uint(type, BPF_MAP_TYPE_ARRAY);
+ __type(key, u32);
+ __type(value, __be64);
+ __uint(max_entries, 1);
+} tx_mac SEC(".maps");
+
static void swap_src_dst_mac(void *data)
{
unsigned short *p = data;
@@ -52,17 +70,16 @@ static void swap_src_dst_mac(void *data)
p[5] = dst[2];
}
-SEC("xdp_redirect_map")
-int xdp_redirect_map_prog(struct xdp_md *ctx)
+static int xdp_redirect_map(struct xdp_md *ctx, void *redirect_map)
{
void *data_end = (void *)(long)ctx->data_end;
void *data = (void *)(long)ctx->data;
struct ethhdr *eth = data;
int rc = XDP_DROP;
- int vport, port = 0, m = 0;
long *value;
u32 key = 0;
u64 nh_off;
+ int vport;
nh_off = sizeof(*eth);
if (data + nh_off > data_end)
@@ -79,7 +96,40 @@ int xdp_redirect_map_prog(struct xdp_md *ctx)
swap_src_dst_mac(data);
/* send packet out physical port */
- return bpf_redirect_map(&tx_port, vport, 0);
+ return bpf_redirect_map(redirect_map, vport, 0);
+}
+
+SEC("xdp_redirect_general")
+int xdp_redirect_map_general(struct xdp_md *ctx)
+{
+ return xdp_redirect_map(ctx, &tx_port_general);
+}
+
+SEC("xdp_redirect_native")
+int xdp_redirect_map_native(struct xdp_md *ctx)
+{
+ return xdp_redirect_map(ctx, &tx_port_native);
+}
+
+SEC("xdp_devmap/map_prog")
+int xdp_redirect_map_egress(struct xdp_md *ctx)
+{
+ void *data_end = (void *)(long)ctx->data_end;
+ void *data = (void *)(long)ctx->data;
+ struct ethhdr *eth = data;
+ __be64 *mac;
+ u32 key = 0;
+ u64 nh_off;
+
+ nh_off = sizeof(*eth);
+ if (data + nh_off > data_end)
+ return XDP_DROP;
+
+ mac = bpf_map_lookup_elem(&tx_mac, &key);
+ if (mac)
+ __builtin_memcpy(eth->h_source, mac, ETH_ALEN);
+
+ return XDP_PASS;
}
/* Redirect require an XDP bpf_prog loaded on the TX device */
diff --git a/samples/bpf/xdp_redirect_map_user.c b/samples/bpf/xdp_redirect_map_user.c
index 31131b6e7782..19636045c8dc 100644
--- a/samples/bpf/xdp_redirect_map_user.c
+++ b/samples/bpf/xdp_redirect_map_user.c
@@ -14,6 +14,10 @@
#include <unistd.h>
#include <libgen.h>
#include <sys/resource.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
#include "bpf_util.h"
#include <bpf/bpf.h>
@@ -21,7 +25,8 @@
static int ifindex_in;
static int ifindex_out;
-static bool ifindex_out_xdp_dummy_attached = true;
+static bool ifindex_out_xdp_dummy_attached = false;
+static bool xdp_devmap_attached = false;
static __u32 prog_id;
static __u32 dummy_prog_id;
@@ -83,6 +88,29 @@ static void poll_stats(int interval, int ifindex)
}
}
+static int get_mac_addr(unsigned int ifindex_out, void *mac_addr)
+{
+ struct ifreq ifr;
+ char ifname[IF_NAMESIZE];
+ int fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
+
+ if (fd < 0)
+ return -1;
+
+ if (!if_indextoname(ifindex_out, ifname))
+ return -1;
+
+ strcpy(ifr.ifr_name, ifname);
+
+ if (ioctl(fd, SIOCGIFHWADDR, &ifr) != 0)
+ return -1;
+
+ memcpy(mac_addr, ifr.ifr_hwaddr.sa_data, 6 * sizeof(char));
+ close(fd);
+
+ return 0;
+}
+
static void usage(const char *prog)
{
fprintf(stderr,
@@ -90,24 +118,26 @@ static void usage(const char *prog)
"OPTS:\n"
" -S use skb-mode\n"
" -N enforce native mode\n"
- " -F force loading prog\n",
+ " -F force loading prog\n"
+ " -X load xdp program on egress\n",
prog);
}
int main(int argc, char **argv)
{
struct bpf_prog_load_attr prog_load_attr = {
- .prog_type = BPF_PROG_TYPE_XDP,
+ .prog_type = BPF_PROG_TYPE_UNSPEC,
};
- struct bpf_program *prog, *dummy_prog;
+ struct bpf_program *prog, *dummy_prog, *devmap_prog;
+ int prog_fd, dummy_prog_fd, devmap_prog_fd = -1;
+ int tx_port_map_fd, tx_mac_map_fd;
+ struct bpf_devmap_val devmap_val;
struct bpf_prog_info info = {};
__u32 info_len = sizeof(info);
- int prog_fd, dummy_prog_fd;
- const char *optstr = "FSN";
+ const char *optstr = "FSNX";
struct bpf_object *obj;
int ret, opt, key = 0;
char filename[256];
- int tx_port_map_fd;
while ((opt = getopt(argc, argv, optstr)) != -1) {
switch (opt) {
@@ -120,6 +150,9 @@ int main(int argc, char **argv)
case 'F':
xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
break;
+ case 'X':
+ xdp_devmap_attached = true;
+ break;
default:
usage(basename(argv[0]));
return 1;
@@ -150,67 +183,107 @@ int main(int argc, char **argv)
if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd))
return 1;
- prog = bpf_program__next(NULL, obj);
- dummy_prog = bpf_program__next(prog, obj);
- if (!prog || !dummy_prog) {
- printf("finding a prog in obj file failed\n");
- return 1;
+ if (xdp_flags & XDP_FLAGS_SKB_MODE) {
+ prog = bpf_object__find_program_by_title(obj, "xdp_redirect_general");
+ tx_port_map_fd = bpf_object__find_map_fd_by_name(obj, "tx_port_general");
+ } else {
+ prog = bpf_object__find_program_by_title(obj, "xdp_redirect_native");
+ tx_port_map_fd = bpf_object__find_map_fd_by_name(obj, "tx_port_native");
}
- /* bpf_prog_load_xattr gives us the pointer to first prog's fd,
- * so we're missing only the fd for dummy prog
- */
- dummy_prog_fd = bpf_program__fd(dummy_prog);
- if (prog_fd < 0 || dummy_prog_fd < 0) {
- printf("bpf_prog_load_xattr: %s\n", strerror(errno));
- return 1;
+ prog_fd = bpf_program__fd(prog);
+ if (!prog || prog_fd < 0 || tx_port_map_fd < 0) {
+ printf("finding prog/tx_port_map in obj file failed\n");
+ goto out;
}
- tx_port_map_fd = bpf_object__find_map_fd_by_name(obj, "tx_port");
rxcnt_map_fd = bpf_object__find_map_fd_by_name(obj, "rxcnt");
- if (tx_port_map_fd < 0 || rxcnt_map_fd < 0) {
+ tx_mac_map_fd = bpf_object__find_map_fd_by_name(obj, "tx_mac");
+ if (rxcnt_map_fd < 0 || tx_mac_map_fd < 0) {
printf("bpf_object__find_map_fd_by_name failed\n");
- return 1;
+ goto out;
}
if (bpf_set_link_xdp_fd(ifindex_in, prog_fd, xdp_flags) < 0) {
printf("ERROR: link set xdp fd failed on %d\n", ifindex_in);
- return 1;
+ goto out;
}
ret = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
if (ret) {
printf("can't get prog info - %s\n", strerror(errno));
- return ret;
+ goto out;
}
prog_id = info.id;
- /* Loading dummy XDP prog on out-device */
- if (bpf_set_link_xdp_fd(ifindex_out, dummy_prog_fd,
- (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;
- }
+ /* If -X supplied, load 2nd xdp prog on egress.
+ * If not, just load dummy prog on egress.
+ */
+ if (xdp_devmap_attached) {
+ unsigned char mac_addr[6];
- memset(&info, 0, sizeof(info));
- ret = bpf_obj_get_info_by_fd(dummy_prog_fd, &info, &info_len);
- if (ret) {
- printf("can't get prog info - %s\n", strerror(errno));
- return ret;
+ devmap_prog = bpf_object__find_program_by_title(obj, "xdp_devmap/map_prog");
+ if (!devmap_prog) {
+ printf("finding devmap_prog in obj file failed\n");
+ goto out;
+ }
+ devmap_prog_fd = bpf_program__fd(devmap_prog);
+ if (devmap_prog_fd < 0) {
+ printf("finding devmap_prog fd failed\n");
+ goto out;
+ }
+
+ if (get_mac_addr(ifindex_out, mac_addr) < 0) {
+ printf("get interface %d mac failed\n", ifindex_out);
+ goto out;
+ }
+
+ ret = bpf_map_update_elem(tx_mac_map_fd, &key, mac_addr, 0);
+ if (ret) {
+ perror("bpf_update_elem tx_mac_map_fd");
+ goto out;
+ }
+ } else if (ifindex_in != ifindex_out) {
+ dummy_prog = bpf_object__find_program_by_title(obj, "xdp_redirect_dummy");
+ if (!dummy_prog) {
+ printf("finding dummy_prog in obj file failed\n");
+ goto out;
+ }
+
+ dummy_prog_fd = bpf_program__fd(dummy_prog);
+ if (dummy_prog_fd < 0) {
+ printf("find dummy_prog fd failed\n");
+ goto out;
+ }
+
+ if (bpf_set_link_xdp_fd(ifindex_out, dummy_prog_fd,
+ (xdp_flags | XDP_FLAGS_UPDATE_IF_NOEXIST)) == 0) {
+ ifindex_out_xdp_dummy_attached = true;
+ } else {
+ printf("WARN: link set xdp fd failed on %d\n", ifindex_out);
+ }
+
+ memset(&info, 0, sizeof(info));
+ ret = bpf_obj_get_info_by_fd(dummy_prog_fd, &info, &info_len);
+ if (ret) {
+ printf("can't get prog info - %s\n", strerror(errno));
+ }
+ dummy_prog_id = info.id;
}
- dummy_prog_id = info.id;
signal(SIGINT, int_exit);
signal(SIGTERM, int_exit);
- /* populate virtual to physical port map */
- ret = bpf_map_update_elem(tx_port_map_fd, &key, &ifindex_out, 0);
+ devmap_val.ifindex = ifindex_out;
+ devmap_val.bpf_prog.fd = devmap_prog_fd;
+ ret = bpf_map_update_elem(tx_port_map_fd, &key, &devmap_val, 0);
if (ret) {
- perror("bpf_update_elem");
+ perror("bpf_update_elem tx_port_map_fd");
goto out;
}
poll_stats(2, ifindex_out);
out:
- return 0;
+ bpf_object__close(obj);
+ return 1;
}
--
2.26.2
