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1/* SPDX-License-Identifier: GPL-2.0
2 * Copyright (c) 2018 Facebook
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of version 2 of the GNU General Public
6 * License as published by the Free Software Foundation.
7 */
8#include <linux/bpf.h>
9#include <linux/if_link.h>
10#include <assert.h>
11#include <errno.h>
12#include <signal.h>
13#include <stdio.h>
14#include <stdlib.h>
15#include <string.h>
16#include <net/if.h>
17#include <arpa/inet.h>
18#include <netinet/ether.h>
19#include <unistd.h>
20#include <time.h>
21#include <bpf/bpf.h>
22#include <bpf/libbpf.h>
23
24#define STATS_INTERVAL_S 2U
25#define MAX_PCKT_SIZE 600
26
27static int ifindex = -1;
28static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
29static __u32 prog_id;
30
31static void int_exit(int sig)
32{
33 __u32 curr_prog_id = 0;
34
35 if (ifindex > -1) {
36 if (bpf_xdp_query_id(ifindex, xdp_flags, &curr_prog_id)) {
37 printf("bpf_xdp_query_id failed\n");
38 exit(1);
39 }
40 if (prog_id == curr_prog_id)
41 bpf_xdp_detach(ifindex, xdp_flags, NULL);
42 else if (!curr_prog_id)
43 printf("couldn't find a prog id on a given iface\n");
44 else
45 printf("program on interface changed, not removing\n");
46 }
47 exit(0);
48}
49
50/* simple "icmp packet too big sent" counter
51 */
52static void poll_stats(unsigned int map_fd, unsigned int kill_after_s)
53{
54 time_t started_at = time(NULL);
55 __u64 value = 0;
56 int key = 0;
57
58
59 while (!kill_after_s || time(NULL) - started_at <= kill_after_s) {
60 sleep(STATS_INTERVAL_S);
61
62 assert(bpf_map_lookup_elem(map_fd, &key, &value) == 0);
63
64 printf("icmp \"packet too big\" sent: %10llu pkts\n", value);
65 }
66}
67
68static void usage(const char *cmd)
69{
70 printf("Start a XDP prog which send ICMP \"packet too big\" \n"
71 "messages if ingress packet is bigger then MAX_SIZE bytes\n");
72 printf("Usage: %s [...]\n", cmd);
73 printf(" -i <ifname|ifindex> Interface\n");
74 printf(" -T <stop-after-X-seconds> Default: 0 (forever)\n");
75 printf(" -P <MAX_PCKT_SIZE> Default: %u\n", MAX_PCKT_SIZE);
76 printf(" -S use skb-mode\n");
77 printf(" -N enforce native mode\n");
78 printf(" -F force loading prog\n");
79 printf(" -h Display this help\n");
80}
81
82int main(int argc, char **argv)
83{
84 unsigned char opt_flags[256] = {};
85 const char *optstr = "i:T:P:SNFh";
86 struct bpf_prog_info info = {};
87 __u32 info_len = sizeof(info);
88 unsigned int kill_after_s = 0;
89 int i, prog_fd, map_fd, opt;
90 struct bpf_program *prog;
91 struct bpf_object *obj;
92 __u32 max_pckt_size = 0;
93 __u32 key = 0;
94 char filename[256];
95 int err;
96
97 for (i = 0; i < strlen(optstr); i++)
98 if (optstr[i] != 'h' && 'a' <= optstr[i] && optstr[i] <= 'z')
99 opt_flags[(unsigned char)optstr[i]] = 1;
100
101 while ((opt = getopt(argc, argv, optstr)) != -1) {
102
103 switch (opt) {
104 case 'i':
105 ifindex = if_nametoindex(optarg);
106 if (!ifindex)
107 ifindex = atoi(optarg);
108 break;
109 case 'T':
110 kill_after_s = atoi(optarg);
111 break;
112 case 'P':
113 max_pckt_size = atoi(optarg);
114 break;
115 case 'S':
116 xdp_flags |= XDP_FLAGS_SKB_MODE;
117 break;
118 case 'N':
119 /* default, set below */
120 break;
121 case 'F':
122 xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
123 break;
124 default:
125 usage(argv[0]);
126 return 1;
127 }
128 opt_flags[opt] = 0;
129 }
130
131 if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
132 xdp_flags |= XDP_FLAGS_DRV_MODE;
133
134 for (i = 0; i < strlen(optstr); i++) {
135 if (opt_flags[(unsigned int)optstr[i]]) {
136 fprintf(stderr, "Missing argument -%c\n", optstr[i]);
137 usage(argv[0]);
138 return 1;
139 }
140 }
141
142 if (!ifindex) {
143 fprintf(stderr, "Invalid ifname\n");
144 return 1;
145 }
146
147 snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
148
149 obj = bpf_object__open_file(filename, NULL);
150 if (libbpf_get_error(obj))
151 return 1;
152
153 prog = bpf_object__next_program(obj, NULL);
154 bpf_program__set_type(prog, BPF_PROG_TYPE_XDP);
155
156 err = bpf_object__load(obj);
157 if (err)
158 return 1;
159
160 prog_fd = bpf_program__fd(prog);
161
162 /* static global var 'max_pcktsz' is accessible from .data section */
163 if (max_pckt_size) {
164 map_fd = bpf_object__find_map_fd_by_name(obj, "xdp_adju.data");
165 if (map_fd < 0) {
166 printf("finding a max_pcktsz map in obj file failed\n");
167 return 1;
168 }
169 bpf_map_update_elem(map_fd, &key, &max_pckt_size, BPF_ANY);
170 }
171
172 /* fetch icmpcnt map */
173 map_fd = bpf_object__find_map_fd_by_name(obj, "icmpcnt");
174 if (map_fd < 0) {
175 printf("finding a icmpcnt map in obj file failed\n");
176 return 1;
177 }
178
179 signal(SIGINT, int_exit);
180 signal(SIGTERM, int_exit);
181
182 if (bpf_xdp_attach(ifindex, prog_fd, xdp_flags, NULL) < 0) {
183 printf("link set xdp fd failed\n");
184 return 1;
185 }
186
187 err = bpf_prog_get_info_by_fd(prog_fd, &info, &info_len);
188 if (err) {
189 printf("can't get prog info - %s\n", strerror(errno));
190 return 1;
191 }
192 prog_id = info.id;
193
194 poll_stats(map_fd, kill_after_s);
195 int_exit(0);
196
197 return 0;
198}
1/* SPDX-License-Identifier: GPL-2.0
2 * Copyright (c) 2018 Facebook
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of version 2 of the GNU General Public
6 * License as published by the Free Software Foundation.
7 */
8#include <linux/bpf.h>
9#include <linux/if_link.h>
10#include <assert.h>
11#include <errno.h>
12#include <signal.h>
13#include <stdio.h>
14#include <stdlib.h>
15#include <string.h>
16#include <net/if.h>
17#include <sys/resource.h>
18#include <arpa/inet.h>
19#include <netinet/ether.h>
20#include <unistd.h>
21#include <time.h>
22#include <bpf/bpf.h>
23#include <bpf/libbpf.h>
24
25#define STATS_INTERVAL_S 2U
26#define MAX_PCKT_SIZE 600
27
28static int ifindex = -1;
29static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
30static __u32 prog_id;
31
32static void int_exit(int sig)
33{
34 __u32 curr_prog_id = 0;
35
36 if (ifindex > -1) {
37 if (bpf_get_link_xdp_id(ifindex, &curr_prog_id, xdp_flags)) {
38 printf("bpf_get_link_xdp_id failed\n");
39 exit(1);
40 }
41 if (prog_id == curr_prog_id)
42 bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
43 else if (!curr_prog_id)
44 printf("couldn't find a prog id on a given iface\n");
45 else
46 printf("program on interface changed, not removing\n");
47 }
48 exit(0);
49}
50
51/* simple "icmp packet too big sent" counter
52 */
53static void poll_stats(unsigned int map_fd, unsigned int kill_after_s)
54{
55 time_t started_at = time(NULL);
56 __u64 value = 0;
57 int key = 0;
58
59
60 while (!kill_after_s || time(NULL) - started_at <= kill_after_s) {
61 sleep(STATS_INTERVAL_S);
62
63 assert(bpf_map_lookup_elem(map_fd, &key, &value) == 0);
64
65 printf("icmp \"packet too big\" sent: %10llu pkts\n", value);
66 }
67}
68
69static void usage(const char *cmd)
70{
71 printf("Start a XDP prog which send ICMP \"packet too big\" \n"
72 "messages if ingress packet is bigger then MAX_SIZE bytes\n");
73 printf("Usage: %s [...]\n", cmd);
74 printf(" -i <ifname|ifindex> Interface\n");
75 printf(" -T <stop-after-X-seconds> Default: 0 (forever)\n");
76 printf(" -P <MAX_PCKT_SIZE> Default: %u\n", MAX_PCKT_SIZE);
77 printf(" -S use skb-mode\n");
78 printf(" -N enforce native mode\n");
79 printf(" -F force loading prog\n");
80 printf(" -h Display this help\n");
81}
82
83int main(int argc, char **argv)
84{
85 struct bpf_prog_load_attr prog_load_attr = {
86 .prog_type = BPF_PROG_TYPE_XDP,
87 };
88 unsigned char opt_flags[256] = {};
89 const char *optstr = "i:T:P:SNFh";
90 struct bpf_prog_info info = {};
91 __u32 info_len = sizeof(info);
92 unsigned int kill_after_s = 0;
93 int i, prog_fd, map_fd, opt;
94 struct bpf_object *obj;
95 __u32 max_pckt_size = 0;
96 __u32 key = 0;
97 char filename[256];
98 int err;
99
100 for (i = 0; i < strlen(optstr); i++)
101 if (optstr[i] != 'h' && 'a' <= optstr[i] && optstr[i] <= 'z')
102 opt_flags[(unsigned char)optstr[i]] = 1;
103
104 while ((opt = getopt(argc, argv, optstr)) != -1) {
105
106 switch (opt) {
107 case 'i':
108 ifindex = if_nametoindex(optarg);
109 if (!ifindex)
110 ifindex = atoi(optarg);
111 break;
112 case 'T':
113 kill_after_s = atoi(optarg);
114 break;
115 case 'P':
116 max_pckt_size = atoi(optarg);
117 break;
118 case 'S':
119 xdp_flags |= XDP_FLAGS_SKB_MODE;
120 break;
121 case 'N':
122 /* default, set below */
123 break;
124 case 'F':
125 xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
126 break;
127 default:
128 usage(argv[0]);
129 return 1;
130 }
131 opt_flags[opt] = 0;
132 }
133
134 if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
135 xdp_flags |= XDP_FLAGS_DRV_MODE;
136
137 for (i = 0; i < strlen(optstr); i++) {
138 if (opt_flags[(unsigned int)optstr[i]]) {
139 fprintf(stderr, "Missing argument -%c\n", optstr[i]);
140 usage(argv[0]);
141 return 1;
142 }
143 }
144
145 if (!ifindex) {
146 fprintf(stderr, "Invalid ifname\n");
147 return 1;
148 }
149
150 snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
151 prog_load_attr.file = filename;
152
153 if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd))
154 return 1;
155
156 /* static global var 'max_pcktsz' is accessible from .data section */
157 if (max_pckt_size) {
158 map_fd = bpf_object__find_map_fd_by_name(obj, "xdp_adju.data");
159 if (map_fd < 0) {
160 printf("finding a max_pcktsz map in obj file failed\n");
161 return 1;
162 }
163 bpf_map_update_elem(map_fd, &key, &max_pckt_size, BPF_ANY);
164 }
165
166 /* fetch icmpcnt map */
167 map_fd = bpf_object__find_map_fd_by_name(obj, "icmpcnt");
168 if (map_fd < 0) {
169 printf("finding a icmpcnt map in obj file failed\n");
170 return 1;
171 }
172
173 signal(SIGINT, int_exit);
174 signal(SIGTERM, int_exit);
175
176 if (bpf_set_link_xdp_fd(ifindex, prog_fd, xdp_flags) < 0) {
177 printf("link set xdp fd failed\n");
178 return 1;
179 }
180
181 err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
182 if (err) {
183 printf("can't get prog info - %s\n", strerror(errno));
184 return 1;
185 }
186 prog_id = info.id;
187
188 poll_stats(map_fd, kill_after_s);
189 int_exit(0);
190
191 return 0;
192}