tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0
2#include <stdio.h>
3#include <stdlib.h>
4#include <string.h>
5#include <linux/perf_event.h>
6#include <linux/bpf.h>
7#include <net/if.h>
8#include <errno.h>
9#include <assert.h>
10#include <sys/sysinfo.h>
11#include <sys/ioctl.h>
12#include <signal.h>
13#include <bpf/libbpf.h>
14#include <bpf/bpf.h>
15#include <sys/resource.h>
16#include <libgen.h>
17#include <linux/if_link.h>
18
19#include "perf-sys.h"
20
21static int if_idx;
22static char *if_name;
23static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
24static __u32 prog_id;
25static struct perf_buffer *pb = NULL;
26
27static int do_attach(int idx, int fd, const char *name)
28{
29 struct bpf_prog_info info = {};
30 __u32 info_len = sizeof(info);
31 int err;
32
33 err = bpf_set_link_xdp_fd(idx, fd, xdp_flags);
34 if (err < 0) {
35 printf("ERROR: failed to attach program to %s\n", name);
36 return err;
37 }
38
39 err = bpf_obj_get_info_by_fd(fd, &info, &info_len);
40 if (err) {
41 printf("can't get prog info - %s\n", strerror(errno));
42 return err;
43 }
44 prog_id = info.id;
45
46 return err;
47}
48
49static int do_detach(int idx, const char *name)
50{
51 __u32 curr_prog_id = 0;
52 int err = 0;
53
54 err = bpf_get_link_xdp_id(idx, &curr_prog_id, xdp_flags);
55 if (err) {
56 printf("bpf_get_link_xdp_id failed\n");
57 return err;
58 }
59 if (prog_id == curr_prog_id) {
60 err = bpf_set_link_xdp_fd(idx, -1, xdp_flags);
61 if (err < 0)
62 printf("ERROR: failed to detach prog from %s\n", name);
63 } else if (!curr_prog_id) {
64 printf("couldn't find a prog id on a %s\n", name);
65 } else {
66 printf("program on interface changed, not removing\n");
67 }
68
69 return err;
70}
71
72#define SAMPLE_SIZE 64
73
74static void print_bpf_output(void *ctx, int cpu, void *data, __u32 size)
75{
76 struct {
77 __u16 cookie;
78 __u16 pkt_len;
79 __u8 pkt_data[SAMPLE_SIZE];
80 } __packed *e = data;
81 int i;
82
83 if (e->cookie != 0xdead) {
84 printf("BUG cookie %x sized %d\n", e->cookie, size);
85 return;
86 }
87
88 printf("Pkt len: %-5d bytes. Ethernet hdr: ", e->pkt_len);
89 for (i = 0; i < 14 && i < e->pkt_len; i++)
90 printf("%02x ", e->pkt_data[i]);
91 printf("\n");
92}
93
94static void sig_handler(int signo)
95{
96 do_detach(if_idx, if_name);
97 perf_buffer__free(pb);
98 exit(0);
99}
100
101static void usage(const char *prog)
102{
103 fprintf(stderr,
104 "%s: %s [OPTS] <ifname|ifindex>\n\n"
105 "OPTS:\n"
106 " -F force loading prog\n",
107 __func__, prog);
108}
109
110int main(int argc, char **argv)
111{
112 struct bpf_prog_load_attr prog_load_attr = {
113 .prog_type = BPF_PROG_TYPE_XDP,
114 };
115 struct perf_buffer_opts pb_opts = {};
116 const char *optstr = "FS";
117 int prog_fd, map_fd, opt;
118 struct bpf_object *obj;
119 struct bpf_map *map;
120 char filename[256];
121 int ret, err;
122
123 while ((opt = getopt(argc, argv, optstr)) != -1) {
124 switch (opt) {
125 case 'F':
126 xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
127 break;
128 case 'S':
129 xdp_flags |= XDP_FLAGS_SKB_MODE;
130 break;
131 default:
132 usage(basename(argv[0]));
133 return 1;
134 }
135 }
136
137 if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
138 xdp_flags |= XDP_FLAGS_DRV_MODE;
139
140 if (optind == argc) {
141 usage(basename(argv[0]));
142 return 1;
143 }
144
145 snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
146 prog_load_attr.file = filename;
147
148 if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd))
149 return 1;
150
151 if (!prog_fd) {
152 printf("bpf_prog_load_xattr: %s\n", strerror(errno));
153 return 1;
154 }
155
156 map = bpf_map__next(NULL, obj);
157 if (!map) {
158 printf("finding a map in obj file failed\n");
159 return 1;
160 }
161 map_fd = bpf_map__fd(map);
162
163 if_idx = if_nametoindex(argv[optind]);
164 if (!if_idx)
165 if_idx = strtoul(argv[optind], NULL, 0);
166
167 if (!if_idx) {
168 fprintf(stderr, "Invalid ifname\n");
169 return 1;
170 }
171 if_name = argv[optind];
172 err = do_attach(if_idx, prog_fd, if_name);
173 if (err)
174 return err;
175
176 if (signal(SIGINT, sig_handler) ||
177 signal(SIGHUP, sig_handler) ||
178 signal(SIGTERM, sig_handler)) {
179 perror("signal");
180 return 1;
181 }
182
183 pb_opts.sample_cb = print_bpf_output;
184 pb = perf_buffer__new(map_fd, 8, &pb_opts);
185 err = libbpf_get_error(pb);
186 if (err) {
187 perror("perf_buffer setup failed");
188 return 1;
189 }
190
191 while ((ret = perf_buffer__poll(pb, 1000)) >= 0) {
192 }
193
194 kill(0, SIGINT);
195 return ret;
196}