xref: /openbmc/linux/samples/bpf/fds_example.c (revision b1fc28b3)
1 #include <linux/unistd.h>
2 #include <linux/bpf.h>
3 
4 #include <stdio.h>
5 #include <stdlib.h>
6 #include <stdint.h>
7 #include <unistd.h>
8 #include <string.h>
9 #include <assert.h>
10 #include <errno.h>
11 
12 #include <sys/types.h>
13 #include <sys/socket.h>
14 
15 #include <bpf/bpf.h>
16 
17 #include <bpf/libbpf.h>
18 #include "bpf_insn.h"
19 #include "sock_example.h"
20 #include "bpf_util.h"
21 
22 #define BPF_F_PIN	(1 << 0)
23 #define BPF_F_GET	(1 << 1)
24 #define BPF_F_PIN_GET	(BPF_F_PIN | BPF_F_GET)
25 
26 #define BPF_F_KEY	(1 << 2)
27 #define BPF_F_VAL	(1 << 3)
28 #define BPF_F_KEY_VAL	(BPF_F_KEY | BPF_F_VAL)
29 
30 #define BPF_M_UNSPEC	0
31 #define BPF_M_MAP	1
32 #define BPF_M_PROG	2
33 
34 char bpf_log_buf[BPF_LOG_BUF_SIZE];
35 
usage(void)36 static void usage(void)
37 {
38 	printf("Usage: fds_example [...]\n");
39 	printf("       -F <file>   File to pin/get object\n");
40 	printf("       -P          |- pin object\n");
41 	printf("       -G          `- get object\n");
42 	printf("       -m          eBPF map mode\n");
43 	printf("       -k <key>    |- map key\n");
44 	printf("       -v <value>  `- map value\n");
45 	printf("       -p          eBPF prog mode\n");
46 	printf("       -o <object> `- object file\n");
47 	printf("       -h          Display this help.\n");
48 }
49 
bpf_prog_create(const char * object)50 static int bpf_prog_create(const char *object)
51 {
52 	static struct bpf_insn insns[] = {
53 		BPF_MOV64_IMM(BPF_REG_0, 1),
54 		BPF_EXIT_INSN(),
55 	};
56 	size_t insns_cnt = ARRAY_SIZE(insns);
57 	struct bpf_object *obj;
58 	int err;
59 
60 	if (object) {
61 		obj = bpf_object__open_file(object, NULL);
62 		assert(!libbpf_get_error(obj));
63 		err = bpf_object__load(obj);
64 		assert(!err);
65 		return bpf_program__fd(bpf_object__next_program(obj, NULL));
66 	} else {
67 		LIBBPF_OPTS(bpf_prog_load_opts, opts,
68 			.log_buf = bpf_log_buf,
69 			.log_size = BPF_LOG_BUF_SIZE,
70 		);
71 
72 		return bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL",
73 				     insns, insns_cnt, &opts);
74 	}
75 }
76 
bpf_do_map(const char * file,uint32_t flags,uint32_t key,uint32_t value)77 static int bpf_do_map(const char *file, uint32_t flags, uint32_t key,
78 		      uint32_t value)
79 {
80 	int fd, ret;
81 
82 	if (flags & BPF_F_PIN) {
83 		fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, NULL, sizeof(uint32_t),
84 				    sizeof(uint32_t), 1024, NULL);
85 		printf("bpf: map fd:%d (%s)\n", fd, strerror(errno));
86 		assert(fd > 0);
87 
88 		ret = bpf_obj_pin(fd, file);
89 		printf("bpf: pin ret:(%d,%s)\n", ret, strerror(errno));
90 		assert(ret == 0);
91 	} else {
92 		fd = bpf_obj_get(file);
93 		printf("bpf: get fd:%d (%s)\n", fd, strerror(errno));
94 		assert(fd > 0);
95 	}
96 
97 	if ((flags & BPF_F_KEY_VAL) == BPF_F_KEY_VAL) {
98 		ret = bpf_map_update_elem(fd, &key, &value, 0);
99 		printf("bpf: fd:%d u->(%u:%u) ret:(%d,%s)\n", fd, key, value,
100 		       ret, strerror(errno));
101 		assert(ret == 0);
102 	} else if (flags & BPF_F_KEY) {
103 		ret = bpf_map_lookup_elem(fd, &key, &value);
104 		printf("bpf: fd:%d l->(%u):%u ret:(%d,%s)\n", fd, key, value,
105 		       ret, strerror(errno));
106 		assert(ret == 0);
107 	}
108 
109 	return 0;
110 }
111 
bpf_do_prog(const char * file,uint32_t flags,const char * object)112 static int bpf_do_prog(const char *file, uint32_t flags, const char *object)
113 {
114 	int fd, sock, ret;
115 
116 	if (flags & BPF_F_PIN) {
117 		fd = bpf_prog_create(object);
118 		printf("bpf: prog fd:%d (%s)\n", fd, strerror(errno));
119 		assert(fd > 0);
120 
121 		ret = bpf_obj_pin(fd, file);
122 		printf("bpf: pin ret:(%d,%s)\n", ret, strerror(errno));
123 		assert(ret == 0);
124 	} else {
125 		fd = bpf_obj_get(file);
126 		printf("bpf: get fd:%d (%s)\n", fd, strerror(errno));
127 		assert(fd > 0);
128 	}
129 
130 	sock = open_raw_sock("lo");
131 	assert(sock > 0);
132 
133 	ret = setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &fd, sizeof(fd));
134 	printf("bpf: sock:%d <- fd:%d attached ret:(%d,%s)\n", sock, fd,
135 	       ret, strerror(errno));
136 	assert(ret == 0);
137 
138 	return 0;
139 }
140 
main(int argc,char ** argv)141 int main(int argc, char **argv)
142 {
143 	const char *file = NULL, *object = NULL;
144 	uint32_t key = 0, value = 0, flags = 0;
145 	int opt, mode = BPF_M_UNSPEC;
146 
147 	while ((opt = getopt(argc, argv, "F:PGmk:v:po:")) != -1) {
148 		switch (opt) {
149 		/* General args */
150 		case 'F':
151 			file = optarg;
152 			break;
153 		case 'P':
154 			flags |= BPF_F_PIN;
155 			break;
156 		case 'G':
157 			flags |= BPF_F_GET;
158 			break;
159 		/* Map-related args */
160 		case 'm':
161 			mode = BPF_M_MAP;
162 			break;
163 		case 'k':
164 			key = strtoul(optarg, NULL, 0);
165 			flags |= BPF_F_KEY;
166 			break;
167 		case 'v':
168 			value = strtoul(optarg, NULL, 0);
169 			flags |= BPF_F_VAL;
170 			break;
171 		/* Prog-related args */
172 		case 'p':
173 			mode = BPF_M_PROG;
174 			break;
175 		case 'o':
176 			object = optarg;
177 			break;
178 		default:
179 			goto out;
180 		}
181 	}
182 
183 	if (!(flags & BPF_F_PIN_GET) || !file)
184 		goto out;
185 
186 	switch (mode) {
187 	case BPF_M_MAP:
188 		return bpf_do_map(file, flags, key, value);
189 	case BPF_M_PROG:
190 		return bpf_do_prog(file, flags, object);
191 	}
192 out:
193 	usage();
194 	return -1;
195 }
196