summaryrefslogtreecommitdiffstats
path: root/samples/bpf/test_cgrp2_sock.c
blob: e79594dd629ba34e066212d80e1549962b3c7d46 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
/* eBPF example program:
 *
 * - Loads eBPF program
 *
 *   The eBPF program sets the sk_bound_dev_if index in new AF_INET{6}
 *   sockets opened by processes in the cgroup.
 *
 * - Attaches the new program to a cgroup using BPF_PROG_ATTACH
 */

#define _GNU_SOURCE

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <unistd.h>
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <net/if.h>
#include <inttypes.h>
#include <linux/bpf.h>

#include "libbpf.h"

char bpf_log_buf[BPF_LOG_BUF_SIZE];

static int prog_load(__u32 idx, __u32 mark, __u32 prio)
{
	/* save pointer to context */
	struct bpf_insn prog_start[] = {
		BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
	};
	struct bpf_insn prog_end[] = {
		BPF_MOV64_IMM(BPF_REG_0, 1), /* r0 = verdict */
		BPF_EXIT_INSN(),
	};

	/* set sk_bound_dev_if on socket */
	struct bpf_insn prog_dev[] = {
		BPF_MOV64_IMM(BPF_REG_3, idx),
		BPF_MOV64_IMM(BPF_REG_2, offsetof(struct bpf_sock, bound_dev_if)),
		BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_3, offsetof(struct bpf_sock, bound_dev_if)),
	};

	/* set mark on socket */
	struct bpf_insn prog_mark[] = {
		/* get uid of process */
		BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
			     BPF_FUNC_get_current_uid_gid),
		BPF_ALU64_IMM(BPF_AND, BPF_REG_0, 0xffffffff),

		/* if uid is 0, use given mark, else use the uid as the mark */
		BPF_MOV64_REG(BPF_REG_3, BPF_REG_0),
		BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
		BPF_MOV64_IMM(BPF_REG_3, mark),

		/* set the mark on the new socket */
		BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
		BPF_MOV64_IMM(BPF_REG_2, offsetof(struct bpf_sock, mark)),
		BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_3, offsetof(struct bpf_sock, mark)),
	};

	/* set priority on socket */
	struct bpf_insn prog_prio[] = {
		BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
		BPF_MOV64_IMM(BPF_REG_3, prio),
		BPF_MOV64_IMM(BPF_REG_2, offsetof(struct bpf_sock, priority)),
		BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_3, offsetof(struct bpf_sock, priority)),
	};

	struct bpf_insn *prog;
	size_t insns_cnt;
	void *p;
	int ret;

	insns_cnt = sizeof(prog_start) + sizeof(prog_end);
	if (idx)
		insns_cnt += sizeof(prog_dev);

	if (mark)
		insns_cnt += sizeof(prog_mark);

	if (prio)
		insns_cnt += sizeof(prog_prio);

	p = prog = malloc(insns_cnt);
	if (!prog) {
		fprintf(stderr, "Failed to allocate memory for instructions\n");
		return EXIT_FAILURE;
	}

	memcpy(p, prog_start, sizeof(prog_start));
	p += sizeof(prog_start);

	if (idx) {
		memcpy(p, prog_dev, sizeof(prog_dev));
		p += sizeof(prog_dev);
	}

	if (mark) {
		memcpy(p, prog_mark, sizeof(prog_mark));
		p += sizeof(prog_mark);
	}

	if (prio) {
		memcpy(p, prog_prio, sizeof(prog_prio));
		p += sizeof(prog_prio);
	}

	memcpy(p, prog_end, sizeof(prog_end));
	p += sizeof(prog_end);

	insns_cnt /= sizeof(struct bpf_insn);

	ret = bpf_load_program(BPF_PROG_TYPE_CGROUP_SOCK, prog, insns_cnt,
				"GPL", 0, bpf_log_buf, BPF_LOG_BUF_SIZE);

	free(prog);

	return ret;
}

static int get_bind_to_device(int sd, char *name, size_t len)
{
	socklen_t optlen = len;
	int rc;

	name[0] = '\0';
	rc = getsockopt(sd, SOL_SOCKET, SO_BINDTODEVICE, name, &optlen);
	if (rc < 0)
		perror("setsockopt(SO_BINDTODEVICE)");

	return rc;
}

static unsigned int get_somark(int sd)
{
	unsigned int mark = 0;
	socklen_t optlen = sizeof(mark);
	int rc;

	rc = getsockopt(sd, SOL_SOCKET, SO_MARK, &mark, &optlen);
	if (rc < 0)
		perror("getsockopt(SO_MARK)");

	return mark;
}

static unsigned int get_priority(int sd)
{
	unsigned int prio = 0;
	socklen_t optlen = sizeof(prio);
	int rc;

	rc = getsockopt(sd, SOL_SOCKET, SO_PRIORITY, &prio, &optlen);
	if (rc < 0)
		perror("getsockopt(SO_PRIORITY)");

	return prio;
}

static int show_sockopts(int family)
{
	unsigned int mark, prio;
	char name[16];
	int sd;

	sd = socket(family, SOCK_DGRAM, 17);
	if (sd < 0) {
		perror("socket");
		return 1;
	}

	if (get_bind_to_device(sd, name, sizeof(name)) < 0)
		return 1;

	mark = get_somark(sd);
	prio = get_priority(sd);

	close(sd);

	printf("sd %d: dev %s, mark %u, priority %u\n", sd, name, mark, prio);

	return 0;
}

static int usage(const char *argv0)
{
	printf("Usage:\n");
	printf("  Attach a program\n");
	printf("  %s -b bind-to-dev -m mark -p prio cg-path\n", argv0);
	printf("\n");
	printf("  Detach a program\n");
	printf("  %s -d cg-path\n", argv0);
	printf("\n");
	printf("  Show inherited socket settings (mark, priority, and device)\n");
	printf("  %s [-6]\n", argv0);
	return EXIT_FAILURE;
}

int main(int argc, char **argv)
{
	__u32 idx = 0, mark = 0, prio = 0;
	const char *cgrp_path = NULL;
	int cg_fd, prog_fd, ret;
	int family = PF_INET;
	int do_attach = 1;
	int rc;

	while ((rc = getopt(argc, argv, "db:m:p:6")) != -1) {
		switch (rc) {
		case 'd':
			do_attach = 0;
			break;
		case 'b':
			idx = if_nametoindex(optarg);
			if (!idx) {
				idx = strtoumax(optarg, NULL, 0);
				if (!idx) {
					printf("Invalid device name\n");
					return EXIT_FAILURE;
				}
			}
			break;
		case 'm':
			mark = strtoumax(optarg, NULL, 0);
			break;
		case 'p':
			prio = strtoumax(optarg, NULL, 0);
			break;
		case '6':
			family = PF_INET6;
			break;
		default:
			return usage(argv[0]);
		}
	}

	if (optind == argc)
		return show_sockopts(family);

	cgrp_path = argv[optind];
	if (!cgrp_path) {
		fprintf(stderr, "cgroup path not given\n");
		return EXIT_FAILURE;
	}

	if (do_attach && !idx && !mark && !prio) {
		fprintf(stderr,
			"One of device, mark or priority must be given\n");
		return EXIT_FAILURE;
	}

	cg_fd = open(cgrp_path, O_DIRECTORY | O_RDONLY);
	if (cg_fd < 0) {
		printf("Failed to open cgroup path: '%s'\n", strerror(errno));
		return EXIT_FAILURE;
	}

	if (do_attach) {
		prog_fd = prog_load(idx, mark, prio);
		if (prog_fd < 0) {
			printf("Failed to load prog: '%s'\n", strerror(errno));
			printf("Output from kernel verifier:\n%s\n-------\n",
			       bpf_log_buf);
			return EXIT_FAILURE;
		}

		ret = bpf_prog_attach(prog_fd, cg_fd,
				      BPF_CGROUP_INET_SOCK_CREATE, 0);
		if (ret < 0) {
			printf("Failed to attach prog to cgroup: '%s'\n",
			       strerror(errno));
			return EXIT_FAILURE;
		}
	} else {
		ret = bpf_prog_detach(cg_fd, BPF_CGROUP_INET_SOCK_CREATE);
		if (ret < 0) {
			printf("Failed to detach prog from cgroup: '%s'\n",
			       strerror(errno));
			return EXIT_FAILURE;
		}
	}

	close(cg_fd);
	return EXIT_SUCCESS;
}
OpenPOWER on IntegriCloud