1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * An implementation of host to guest copy functionality for Linux.
4 *
5 * Copyright (C) 2014, Microsoft, Inc.
6 *
7 * Author : K. Y. Srinivasan <kys@microsoft.com>
8 */
9
10
11#include <sys/types.h>
12#include <stdio.h>
13#include <stdlib.h>
14#include <unistd.h>
15#include <string.h>
16#include <errno.h>
17#include <linux/hyperv.h>
18#include <linux/limits.h>
19#include <syslog.h>
20#include <sys/stat.h>
21#include <fcntl.h>
22#include <getopt.h>
23
24static int target_fd;
25static char target_fname[PATH_MAX];
26static unsigned long long filesize;
27
28static int hv_start_fcopy(struct hv_start_fcopy *smsg)
29{
30	int error = HV_E_FAIL;
31	char *q, *p;
32
33	filesize = 0;
34	p = (char *)smsg->path_name;
35	snprintf(target_fname, sizeof(target_fname), "%s/%s",
36		 (char *)smsg->path_name, (char *)smsg->file_name);
37
38	syslog(LOG_INFO, "Target file name: %s", target_fname);
39	/*
40	 * Check to see if the path is already in place; if not,
41	 * create if required.
42	 */
43	while ((q = strchr(p, '/')) != NULL) {
44		if (q == p) {
45			p++;
46			continue;
47		}
48		*q = '\0';
49		if (access((char *)smsg->path_name, F_OK)) {
50			if (smsg->copy_flags & CREATE_PATH) {
51				if (mkdir((char *)smsg->path_name, 0755)) {
52					syslog(LOG_ERR, "Failed to create %s",
53						(char *)smsg->path_name);
54					goto done;
55				}
56			} else {
57				syslog(LOG_ERR, "Invalid path: %s",
58					(char *)smsg->path_name);
59				goto done;
60			}
61		}
62		p = q + 1;
63		*q = '/';
64	}
65
66	if (!access(target_fname, F_OK)) {
67		syslog(LOG_INFO, "File: %s exists", target_fname);
68		if (!(smsg->copy_flags & OVER_WRITE)) {
69			error = HV_ERROR_ALREADY_EXISTS;
70			goto done;
71		}
72	}
73
74	target_fd = open(target_fname,
75			 O_RDWR | O_CREAT | O_TRUNC | O_CLOEXEC, 0744);
76	if (target_fd == -1) {
77		syslog(LOG_INFO, "Open Failed: %s", strerror(errno));
78		goto done;
79	}
80
81	error = 0;
82done:
83	if (error)
84		target_fname[0] = '\0';
85	return error;
86}
87
88static int hv_copy_data(struct hv_do_fcopy *cpmsg)
89{
90	ssize_t bytes_written;
91	int ret = 0;
92
93	bytes_written = pwrite(target_fd, cpmsg->data, cpmsg->size,
94				cpmsg->offset);
95
96	filesize += cpmsg->size;
97	if (bytes_written != cpmsg->size) {
98		switch (errno) {
99		case ENOSPC:
100			ret = HV_ERROR_DISK_FULL;
101			break;
102		default:
103			ret = HV_E_FAIL;
104			break;
105		}
106		syslog(LOG_ERR, "pwrite failed to write %llu bytes: %ld (%s)",
107		       filesize, (long)bytes_written, strerror(errno));
108	}
109
110	return ret;
111}
112
113/*
114 * Reset target_fname to "" in the two below functions for hibernation: if
115 * the fcopy operation is aborted by hibernation, the daemon should remove the
116 * partially-copied file; to achieve this, the hv_utils driver always fakes a
117 * CANCEL_FCOPY message upon suspend, and later when the VM resumes back,
118 * the daemon calls hv_copy_cancel() to remove the file; if a file is copied
119 * successfully before suspend, hv_copy_finished() must reset target_fname to
120 * avoid that the file can be incorrectly removed upon resume, since the faked
121 * CANCEL_FCOPY message is spurious in this case.
122 */
123static int hv_copy_finished(void)
124{
125	close(target_fd);
126	target_fname[0] = '\0';
127	return 0;
128}
129static int hv_copy_cancel(void)
130{
131	close(target_fd);
132	if (strlen(target_fname) > 0) {
133		unlink(target_fname);
134		target_fname[0] = '\0';
135	}
136	return 0;
137
138}
139
140void print_usage(char *argv[])
141{
142	fprintf(stderr, "Usage: %s [options]\n"
143		"Options are:\n"
144		"  -n, --no-daemon        stay in foreground, don't daemonize\n"
145		"  -h, --help             print this help\n", argv[0]);
146}
147
148int main(int argc, char *argv[])
149{
150	int fcopy_fd = -1;
151	int error;
152	int daemonize = 1, long_index = 0, opt;
153	int version = FCOPY_CURRENT_VERSION;
154	union {
155		struct hv_fcopy_hdr hdr;
156		struct hv_start_fcopy start;
157		struct hv_do_fcopy copy;
158		__u32 kernel_modver;
159	} buffer = { };
160	int in_handshake;
161
162	static struct option long_options[] = {
163		{"help",	no_argument,	   0,  'h' },
164		{"no-daemon",	no_argument,	   0,  'n' },
165		{0,		0,		   0,  0   }
166	};
167
168	while ((opt = getopt_long(argc, argv, "hn", long_options,
169				  &long_index)) != -1) {
170		switch (opt) {
171		case 'n':
172			daemonize = 0;
173			break;
174		case 'h':
175		default:
176			print_usage(argv);
177			exit(EXIT_FAILURE);
178		}
179	}
180
181	if (daemonize && daemon(1, 0)) {
182		syslog(LOG_ERR, "daemon() failed; error: %s", strerror(errno));
183		exit(EXIT_FAILURE);
184	}
185
186	openlog("HV_FCOPY", 0, LOG_USER);
187	syslog(LOG_INFO, "starting; pid is:%d", getpid());
188
189reopen_fcopy_fd:
190	if (fcopy_fd != -1)
191		close(fcopy_fd);
192	/* Remove any possible partially-copied file on error */
193	hv_copy_cancel();
194	in_handshake = 1;
195	fcopy_fd = open("/dev/vmbus/hv_fcopy", O_RDWR);
196
197	if (fcopy_fd < 0) {
198		syslog(LOG_ERR, "open /dev/vmbus/hv_fcopy failed; error: %d %s",
199			errno, strerror(errno));
200		exit(EXIT_FAILURE);
201	}
202
203	/*
204	 * Register with the kernel.
205	 */
206	if ((write(fcopy_fd, &version, sizeof(int))) != sizeof(int)) {
207		syslog(LOG_ERR, "Registration failed: %s", strerror(errno));
208		exit(EXIT_FAILURE);
209	}
210
211	while (1) {
212		/*
213		 * In this loop we process fcopy messages after the
214		 * handshake is complete.
215		 */
216		ssize_t len;
217
218		len = pread(fcopy_fd, &buffer, sizeof(buffer), 0);
219		if (len < 0) {
220			syslog(LOG_ERR, "pread failed: %s", strerror(errno));
221			goto reopen_fcopy_fd;
222		}
223
224		if (in_handshake) {
225			if (len != sizeof(buffer.kernel_modver)) {
226				syslog(LOG_ERR, "invalid version negotiation");
227				exit(EXIT_FAILURE);
228			}
229			in_handshake = 0;
230			syslog(LOG_INFO, "kernel module version: %u",
231			       buffer.kernel_modver);
232			continue;
233		}
234
235		switch (buffer.hdr.operation) {
236		case START_FILE_COPY:
237			error = hv_start_fcopy(&buffer.start);
238			break;
239		case WRITE_TO_FILE:
240			error = hv_copy_data(&buffer.copy);
241			break;
242		case COMPLETE_FCOPY:
243			error = hv_copy_finished();
244			break;
245		case CANCEL_FCOPY:
246			error = hv_copy_cancel();
247			break;
248
249		default:
250			error = HV_E_FAIL;
251			syslog(LOG_ERR, "Unknown operation: %d",
252				buffer.hdr.operation);
253
254		}
255
256		/*
257		 * pwrite() may return an error due to the faked CANCEL_FCOPY
258		 * message upon hibernation. Ignore the error by resetting the
259		 * dev file, i.e. closing and re-opening it.
260		 */
261		if (pwrite(fcopy_fd, &error, sizeof(int), 0) != sizeof(int)) {
262			syslog(LOG_ERR, "pwrite failed: %s", strerror(errno));
263			goto reopen_fcopy_fd;
264		}
265	}
266}
267