This source file includes following definitions.
- int_exit
- poll_stats
- usage
- main
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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.h"
23 #include "libbpf.h"
24
25 #define STATS_INTERVAL_S 2U
26
27 static int ifindex = -1;
28 static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
29 static __u32 prog_id;
30
31 static void int_exit(int sig)
32 {
33 __u32 curr_prog_id = 0;
34
35 if (ifindex > -1) {
36 if (bpf_get_link_xdp_id(ifindex, &curr_prog_id, xdp_flags)) {
37 printf("bpf_get_link_xdp_id failed\n");
38 exit(1);
39 }
40 if (prog_id == curr_prog_id)
41 bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
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
51
52 static 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
68 static 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(" -S use skb-mode\n");
76 printf(" -N enforce native mode\n");
77 printf(" -F force loading prog\n");
78 printf(" -h Display this help\n");
79 }
80
81 int main(int argc, char **argv)
82 {
83 struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
84 struct bpf_prog_load_attr prog_load_attr = {
85 .prog_type = BPF_PROG_TYPE_XDP,
86 };
87 unsigned char opt_flags[256] = {};
88 const char *optstr = "i:T:SNFh";
89 struct bpf_prog_info info = {};
90 __u32 info_len = sizeof(info);
91 unsigned int kill_after_s = 0;
92 int i, prog_fd, map_fd, opt;
93 struct bpf_object *obj;
94 struct bpf_map *map;
95 char filename[256];
96 int err;
97
98 for (i = 0; i < strlen(optstr); i++)
99 if (optstr[i] != 'h' && 'a' <= optstr[i] && optstr[i] <= 'z')
100 opt_flags[(unsigned char)optstr[i]] = 1;
101
102 while ((opt = getopt(argc, argv, optstr)) != -1) {
103
104 switch (opt) {
105 case 'i':
106 ifindex = if_nametoindex(optarg);
107 if (!ifindex)
108 ifindex = atoi(optarg);
109 break;
110 case 'T':
111 kill_after_s = atoi(optarg);
112 break;
113 case 'S':
114 xdp_flags |= XDP_FLAGS_SKB_MODE;
115 break;
116 case 'N':
117 xdp_flags |= XDP_FLAGS_DRV_MODE;
118 break;
119 case 'F':
120 xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
121 break;
122 default:
123 usage(argv[0]);
124 return 1;
125 }
126 opt_flags[opt] = 0;
127 }
128
129 for (i = 0; i < strlen(optstr); i++) {
130 if (opt_flags[(unsigned int)optstr[i]]) {
131 fprintf(stderr, "Missing argument -%c\n", optstr[i]);
132 usage(argv[0]);
133 return 1;
134 }
135 }
136
137 if (setrlimit(RLIMIT_MEMLOCK, &r)) {
138 perror("setrlimit(RLIMIT_MEMLOCK, RLIM_INFINITY)");
139 return 1;
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 prog_load_attr.file = filename;
149
150 if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd))
151 return 1;
152
153 map = bpf_map__next(NULL, obj);
154 if (!map) {
155 printf("finding a map in obj file failed\n");
156 return 1;
157 }
158 map_fd = bpf_map__fd(map);
159
160 if (!prog_fd) {
161 printf("load_bpf_file: %s\n", strerror(errno));
162 return 1;
163 }
164
165 signal(SIGINT, int_exit);
166 signal(SIGTERM, int_exit);
167
168 if (bpf_set_link_xdp_fd(ifindex, prog_fd, xdp_flags) < 0) {
169 printf("link set xdp fd failed\n");
170 return 1;
171 }
172
173 err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
174 if (err) {
175 printf("can't get prog info - %s\n", strerror(errno));
176 return 1;
177 }
178 prog_id = info.id;
179
180 poll_stats(map_fd, kill_after_s);
181 int_exit(0);
182
183 return 0;
184 }