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
24 static int target_fd;
25 static char target_fname[PATH_MAX];
26 static unsigned long long filesize;
27
hv_start_fcopy(struct hv_start_fcopy * smsg)28 static 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;
82 done:
83 if (error)
84 target_fname[0] = '\0';
85 return error;
86 }
87
hv_copy_data(struct hv_do_fcopy * cpmsg)88 static 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 */
hv_copy_finished(void)123 static int hv_copy_finished(void)
124 {
125 close(target_fd);
126 target_fname[0] = '\0';
127 return 0;
128 }
hv_copy_cancel(void)129 static 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
print_usage(char * argv[])140 void 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
main(int argc,char * argv[])148 int 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
189 reopen_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