summaryrefslogtreecommitdiff
path: root/tools/hv/hv_vss_daemon.c
blob: 506dd01488286f8033f3ceaf3915fd06742f33de (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
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
/*
 * An implementation of the host initiated guest snapshot for Hyper-V.
 *
 *
 * Copyright (C) 2013, Microsoft, Inc.
 * Author : K. Y. Srinivasan <kys@microsoft.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 * NON INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 */


#include <sys/types.h>
#include <sys/socket.h>
#include <sys/poll.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <stdio.h>
#include <mntent.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <arpa/inet.h>
#include <linux/fs.h>
#include <linux/connector.h>
#include <linux/hyperv.h>
#include <linux/netlink.h>
#include <syslog.h>
#include <getopt.h>

static struct sockaddr_nl addr;

#ifndef SOL_NETLINK
#define SOL_NETLINK 270
#endif


/* Don't use syslog() in the function since that can cause write to disk */
static int vss_do_freeze(char *dir, unsigned int cmd)
{
	int ret, fd = open(dir, O_RDONLY);

	if (fd < 0)
		return 1;

	ret = ioctl(fd, cmd, 0);

	/*
	 * If a partition is mounted more than once, only the first
	 * FREEZE/THAW can succeed and the later ones will get
	 * EBUSY/EINVAL respectively: there could be 2 cases:
	 * 1) a user may mount the same partition to differnt directories
	 *  by mistake or on purpose;
	 * 2) The subvolume of btrfs appears to have the same partition
	 * mounted more than once.
	 */
	if (ret) {
		if ((cmd == FIFREEZE && errno == EBUSY) ||
		    (cmd == FITHAW && errno == EINVAL)) {
			close(fd);
			return 0;
		}
	}

	close(fd);
	return !!ret;
}

static int vss_operate(int operation)
{
	char match[] = "/dev/";
	FILE *mounts;
	struct mntent *ent;
	char errdir[1024] = {0};
	unsigned int cmd;
	int error = 0, root_seen = 0, save_errno = 0;

	switch (operation) {
	case VSS_OP_FREEZE:
		cmd = FIFREEZE;
		break;
	case VSS_OP_THAW:
		cmd = FITHAW;
		break;
	default:
		return -1;
	}

	mounts = setmntent("/proc/mounts", "r");
	if (mounts == NULL)
		return -1;

	while ((ent = getmntent(mounts))) {
		if (strncmp(ent->mnt_fsname, match, strlen(match)))
			continue;
		if (hasmntopt(ent, MNTOPT_RO) != NULL)
			continue;
		if (strcmp(ent->mnt_type, "vfat") == 0)
			continue;
		if (strcmp(ent->mnt_dir, "/") == 0) {
			root_seen = 1;
			continue;
		}
		error |= vss_do_freeze(ent->mnt_dir, cmd);
		if (error && operation == VSS_OP_FREEZE)
			goto err;
	}

	endmntent(mounts);

	if (root_seen) {
		error |= vss_do_freeze("/", cmd);
		if (error && operation == VSS_OP_FREEZE)
			goto err;
	}

	goto out;
err:
	save_errno = errno;
	if (ent) {
		strncpy(errdir, ent->mnt_dir, sizeof(errdir)-1);
		endmntent(mounts);
	}
	vss_operate(VSS_OP_THAW);
	/* Call syslog after we thaw all filesystems */
	if (ent)
		syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s",
		       errdir, save_errno, strerror(save_errno));
	else
		syslog(LOG_ERR, "FREEZE of / failed; error:%d %s", save_errno,
		       strerror(save_errno));
out:
	return error;
}

static int netlink_send(int fd, struct cn_msg *msg)
{
	struct nlmsghdr nlh = { .nlmsg_type = NLMSG_DONE };
	unsigned int size;
	struct msghdr message;
	struct iovec iov[2];

	size = sizeof(struct cn_msg) + msg->len;

	nlh.nlmsg_pid = getpid();
	nlh.nlmsg_len = NLMSG_LENGTH(size);

	iov[0].iov_base = &nlh;
	iov[0].iov_len = sizeof(nlh);

	iov[1].iov_base = msg;
	iov[1].iov_len = size;

	memset(&message, 0, sizeof(message));
	message.msg_name = &addr;
	message.msg_namelen = sizeof(addr);
	message.msg_iov = iov;
	message.msg_iovlen = 2;

	return sendmsg(fd, &message, 0);
}

void print_usage(char *argv[])
{
	fprintf(stderr, "Usage: %s [options]\n"
		"Options are:\n"
		"  -n, --no-daemon        stay in foreground, don't daemonize\n"
		"  -h, --help             print this help\n", argv[0]);
}

int main(int argc, char *argv[])
{
	int fd, len, nl_group;
	int error;
	struct cn_msg *message;
	struct pollfd pfd;
	struct nlmsghdr *incoming_msg;
	struct cn_msg	*incoming_cn_msg;
	int	op;
	struct hv_vss_msg *vss_msg;
	char *vss_recv_buffer;
	size_t vss_recv_buffer_len;
	int daemonize = 1, long_index = 0, opt;

	static struct option long_options[] = {
		{"help",	no_argument,	   0,  'h' },
		{"no-daemon",	no_argument,	   0,  'n' },
		{0,		0,		   0,  0   }
	};

	while ((opt = getopt_long(argc, argv, "hn", long_options,
				  &long_index)) != -1) {
		switch (opt) {
		case 'n':
			daemonize = 0;
			break;
		case 'h':
		default:
			print_usage(argv);
			exit(EXIT_FAILURE);
		}
	}

	if (daemonize && daemon(1, 0))
		return 1;

	openlog("Hyper-V VSS", 0, LOG_USER);
	syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());

	vss_recv_buffer_len = NLMSG_LENGTH(0) + sizeof(struct cn_msg) + sizeof(struct hv_vss_msg);
	vss_recv_buffer = calloc(1, vss_recv_buffer_len);
	if (!vss_recv_buffer) {
		syslog(LOG_ERR, "Failed to allocate netlink buffers");
		exit(EXIT_FAILURE);
	}

	fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
	if (fd < 0) {
		syslog(LOG_ERR, "netlink socket creation failed; error:%d %s",
				errno, strerror(errno));
		exit(EXIT_FAILURE);
	}
	addr.nl_family = AF_NETLINK;
	addr.nl_pad = 0;
	addr.nl_pid = 0;
	addr.nl_groups = 0;


	error = bind(fd, (struct sockaddr *)&addr, sizeof(addr));
	if (error < 0) {
		syslog(LOG_ERR, "bind failed; error:%d %s", errno, strerror(errno));
		close(fd);
		exit(EXIT_FAILURE);
	}
	nl_group = CN_VSS_IDX;
	if (setsockopt(fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &nl_group, sizeof(nl_group)) < 0) {
		syslog(LOG_ERR, "setsockopt failed; error:%d %s", errno, strerror(errno));
		close(fd);
		exit(EXIT_FAILURE);
	}
	/*
	 * Register ourselves with the kernel.
	 */
	message = (struct cn_msg *)vss_recv_buffer;
	message->id.idx = CN_VSS_IDX;
	message->id.val = CN_VSS_VAL;
	message->ack = 0;
	vss_msg = (struct hv_vss_msg *)message->data;
	vss_msg->vss_hdr.operation = VSS_OP_REGISTER;

	message->len = sizeof(struct hv_vss_msg);

	len = netlink_send(fd, message);
	if (len < 0) {
		syslog(LOG_ERR, "netlink_send failed; error:%d %s", errno, strerror(errno));
		close(fd);
		exit(EXIT_FAILURE);
	}

	pfd.fd = fd;

	while (1) {
		struct sockaddr *addr_p = (struct sockaddr *) &addr;
		socklen_t addr_l = sizeof(addr);
		pfd.events = POLLIN;
		pfd.revents = 0;

		if (poll(&pfd, 1, -1) < 0) {
			syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno));
			if (errno == EINVAL) {
				close(fd);
				exit(EXIT_FAILURE);
			}
			else
				continue;
		}

		len = recvfrom(fd, vss_recv_buffer, vss_recv_buffer_len, 0,
				addr_p, &addr_l);

		if (len < 0) {
			syslog(LOG_ERR, "recvfrom failed; pid:%u error:%d %s",
					addr.nl_pid, errno, strerror(errno));
			close(fd);
			return -1;
		}

		if (addr.nl_pid) {
			syslog(LOG_WARNING,
				"Received packet from untrusted pid:%u",
				addr.nl_pid);
			continue;
		}

		incoming_msg = (struct nlmsghdr *)vss_recv_buffer;

		if (incoming_msg->nlmsg_type != NLMSG_DONE)
			continue;

		incoming_cn_msg = (struct cn_msg *)NLMSG_DATA(incoming_msg);
		vss_msg = (struct hv_vss_msg *)incoming_cn_msg->data;
		op = vss_msg->vss_hdr.operation;
		error =  HV_S_OK;

		switch (op) {
		case VSS_OP_FREEZE:
		case VSS_OP_THAW:
			error = vss_operate(op);
			syslog(LOG_INFO, "VSS: op=%s: %s\n",
				op == VSS_OP_FREEZE ? "FREEZE" : "THAW",
				error ? "failed" : "succeeded");

			if (error) {
				error = HV_E_FAIL;
				syslog(LOG_ERR, "op=%d failed!", op);
				syslog(LOG_ERR, "report it with these files:");
				syslog(LOG_ERR, "/etc/fstab and /proc/mounts");
			}
			break;
		default:
			syslog(LOG_ERR, "Illegal op:%d\n", op);
		}
		vss_msg->error = error;
		len = netlink_send(fd, incoming_cn_msg);
		if (len < 0) {
			syslog(LOG_ERR, "net_link send failed; error:%d %s",
					errno, strerror(errno));
			exit(EXIT_FAILURE);
		}
	}

}