1 /* 2 * An implementation of the host initiated guest snapshot for Hyper-V. 3 * 4 * 5 * Copyright (C) 2013, Microsoft, Inc. 6 * Author : K. Y. Srinivasan <kys@microsoft.com> 7 * 8 * This program is free software; you can redistribute it and/or modify it 9 * under the terms of the GNU General Public License version 2 as published 10 * by the Free Software Foundation. 11 * 12 * This program is distributed in the hope that it will be useful, but 13 * WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or 15 * NON INFRINGEMENT. See the GNU General Public License for more 16 * details. 17 * 18 */ 19 20 21 #include <sys/types.h> 22 #include <sys/socket.h> 23 #include <sys/poll.h> 24 #include <sys/ioctl.h> 25 #include <fcntl.h> 26 #include <stdio.h> 27 #include <mntent.h> 28 #include <stdlib.h> 29 #include <unistd.h> 30 #include <string.h> 31 #include <ctype.h> 32 #include <errno.h> 33 #include <arpa/inet.h> 34 #include <linux/fs.h> 35 #include <linux/connector.h> 36 #include <linux/hyperv.h> 37 #include <linux/netlink.h> 38 #include <syslog.h> 39 #include <getopt.h> 40 41 static struct sockaddr_nl addr; 42 43 #ifndef SOL_NETLINK 44 #define SOL_NETLINK 270 45 #endif 46 47 48 /* Don't use syslog() in the function since that can cause write to disk */ 49 static int vss_do_freeze(char *dir, unsigned int cmd) 50 { 51 int ret, fd = open(dir, O_RDONLY); 52 53 if (fd < 0) 54 return 1; 55 56 ret = ioctl(fd, cmd, 0); 57 58 /* 59 * If a partition is mounted more than once, only the first 60 * FREEZE/THAW can succeed and the later ones will get 61 * EBUSY/EINVAL respectively: there could be 2 cases: 62 * 1) a user may mount the same partition to differnt directories 63 * by mistake or on purpose; 64 * 2) The subvolume of btrfs appears to have the same partition 65 * mounted more than once. 66 */ 67 if (ret) { 68 if ((cmd == FIFREEZE && errno == EBUSY) || 69 (cmd == FITHAW && errno == EINVAL)) { 70 close(fd); 71 return 0; 72 } 73 } 74 75 close(fd); 76 return !!ret; 77 } 78 79 static int vss_operate(int operation) 80 { 81 char match[] = "/dev/"; 82 FILE *mounts; 83 struct mntent *ent; 84 char errdir[1024] = {0}; 85 unsigned int cmd; 86 int error = 0, root_seen = 0, save_errno = 0; 87 88 switch (operation) { 89 case VSS_OP_FREEZE: 90 cmd = FIFREEZE; 91 break; 92 case VSS_OP_THAW: 93 cmd = FITHAW; 94 break; 95 default: 96 return -1; 97 } 98 99 mounts = setmntent("/proc/mounts", "r"); 100 if (mounts == NULL) 101 return -1; 102 103 while ((ent = getmntent(mounts))) { 104 if (strncmp(ent->mnt_fsname, match, strlen(match))) 105 continue; 106 if (hasmntopt(ent, MNTOPT_RO) != NULL) 107 continue; 108 if (strcmp(ent->mnt_type, "vfat") == 0) 109 continue; 110 if (strcmp(ent->mnt_dir, "/") == 0) { 111 root_seen = 1; 112 continue; 113 } 114 error |= vss_do_freeze(ent->mnt_dir, cmd); 115 if (error && operation == VSS_OP_FREEZE) 116 goto err; 117 } 118 119 endmntent(mounts); 120 121 if (root_seen) { 122 error |= vss_do_freeze("/", cmd); 123 if (error && operation == VSS_OP_FREEZE) 124 goto err; 125 } 126 127 goto out; 128 err: 129 save_errno = errno; 130 if (ent) { 131 strncpy(errdir, ent->mnt_dir, sizeof(errdir)-1); 132 endmntent(mounts); 133 } 134 vss_operate(VSS_OP_THAW); 135 /* Call syslog after we thaw all filesystems */ 136 if (ent) 137 syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s", 138 errdir, save_errno, strerror(save_errno)); 139 else 140 syslog(LOG_ERR, "FREEZE of / failed; error:%d %s", save_errno, 141 strerror(save_errno)); 142 out: 143 return error; 144 } 145 146 static int netlink_send(int fd, struct cn_msg *msg) 147 { 148 struct nlmsghdr nlh = { .nlmsg_type = NLMSG_DONE }; 149 unsigned int size; 150 struct msghdr message; 151 struct iovec iov[2]; 152 153 size = sizeof(struct cn_msg) + msg->len; 154 155 nlh.nlmsg_pid = getpid(); 156 nlh.nlmsg_len = NLMSG_LENGTH(size); 157 158 iov[0].iov_base = &nlh; 159 iov[0].iov_len = sizeof(nlh); 160 161 iov[1].iov_base = msg; 162 iov[1].iov_len = size; 163 164 memset(&message, 0, sizeof(message)); 165 message.msg_name = &addr; 166 message.msg_namelen = sizeof(addr); 167 message.msg_iov = iov; 168 message.msg_iovlen = 2; 169 170 return sendmsg(fd, &message, 0); 171 } 172 173 void print_usage(char *argv[]) 174 { 175 fprintf(stderr, "Usage: %s [options]\n" 176 "Options are:\n" 177 " -n, --no-daemon stay in foreground, don't daemonize\n" 178 " -h, --help print this help\n", argv[0]); 179 } 180 181 int main(int argc, char *argv[]) 182 { 183 int fd, len, nl_group; 184 int error; 185 struct cn_msg *message; 186 struct pollfd pfd; 187 struct nlmsghdr *incoming_msg; 188 struct cn_msg *incoming_cn_msg; 189 int op; 190 struct hv_vss_msg *vss_msg; 191 char *vss_recv_buffer; 192 size_t vss_recv_buffer_len; 193 int daemonize = 1, long_index = 0, opt; 194 195 static struct option long_options[] = { 196 {"help", no_argument, 0, 'h' }, 197 {"no-daemon", no_argument, 0, 'n' }, 198 {0, 0, 0, 0 } 199 }; 200 201 while ((opt = getopt_long(argc, argv, "hn", long_options, 202 &long_index)) != -1) { 203 switch (opt) { 204 case 'n': 205 daemonize = 0; 206 break; 207 case 'h': 208 default: 209 print_usage(argv); 210 exit(EXIT_FAILURE); 211 } 212 } 213 214 if (daemonize && daemon(1, 0)) 215 return 1; 216 217 openlog("Hyper-V VSS", 0, LOG_USER); 218 syslog(LOG_INFO, "VSS starting; pid is:%d", getpid()); 219 220 vss_recv_buffer_len = NLMSG_LENGTH(0) + sizeof(struct cn_msg) + sizeof(struct hv_vss_msg); 221 vss_recv_buffer = calloc(1, vss_recv_buffer_len); 222 if (!vss_recv_buffer) { 223 syslog(LOG_ERR, "Failed to allocate netlink buffers"); 224 exit(EXIT_FAILURE); 225 } 226 227 fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR); 228 if (fd < 0) { 229 syslog(LOG_ERR, "netlink socket creation failed; error:%d %s", 230 errno, strerror(errno)); 231 exit(EXIT_FAILURE); 232 } 233 addr.nl_family = AF_NETLINK; 234 addr.nl_pad = 0; 235 addr.nl_pid = 0; 236 addr.nl_groups = 0; 237 238 239 error = bind(fd, (struct sockaddr *)&addr, sizeof(addr)); 240 if (error < 0) { 241 syslog(LOG_ERR, "bind failed; error:%d %s", errno, strerror(errno)); 242 close(fd); 243 exit(EXIT_FAILURE); 244 } 245 nl_group = CN_VSS_IDX; 246 if (setsockopt(fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &nl_group, sizeof(nl_group)) < 0) { 247 syslog(LOG_ERR, "setsockopt failed; error:%d %s", errno, strerror(errno)); 248 close(fd); 249 exit(EXIT_FAILURE); 250 } 251 /* 252 * Register ourselves with the kernel. 253 */ 254 message = (struct cn_msg *)vss_recv_buffer; 255 message->id.idx = CN_VSS_IDX; 256 message->id.val = CN_VSS_VAL; 257 message->ack = 0; 258 vss_msg = (struct hv_vss_msg *)message->data; 259 vss_msg->vss_hdr.operation = VSS_OP_REGISTER; 260 261 message->len = sizeof(struct hv_vss_msg); 262 263 len = netlink_send(fd, message); 264 if (len < 0) { 265 syslog(LOG_ERR, "netlink_send failed; error:%d %s", errno, strerror(errno)); 266 close(fd); 267 exit(EXIT_FAILURE); 268 } 269 270 pfd.fd = fd; 271 272 while (1) { 273 struct sockaddr *addr_p = (struct sockaddr *) &addr; 274 socklen_t addr_l = sizeof(addr); 275 pfd.events = POLLIN; 276 pfd.revents = 0; 277 278 if (poll(&pfd, 1, -1) < 0) { 279 syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno)); 280 if (errno == EINVAL) { 281 close(fd); 282 exit(EXIT_FAILURE); 283 } 284 else 285 continue; 286 } 287 288 len = recvfrom(fd, vss_recv_buffer, vss_recv_buffer_len, 0, 289 addr_p, &addr_l); 290 291 if (len < 0) { 292 syslog(LOG_ERR, "recvfrom failed; pid:%u error:%d %s", 293 addr.nl_pid, errno, strerror(errno)); 294 close(fd); 295 return -1; 296 } 297 298 if (addr.nl_pid) { 299 syslog(LOG_WARNING, 300 "Received packet from untrusted pid:%u", 301 addr.nl_pid); 302 continue; 303 } 304 305 incoming_msg = (struct nlmsghdr *)vss_recv_buffer; 306 307 if (incoming_msg->nlmsg_type != NLMSG_DONE) 308 continue; 309 310 incoming_cn_msg = (struct cn_msg *)NLMSG_DATA(incoming_msg); 311 vss_msg = (struct hv_vss_msg *)incoming_cn_msg->data; 312 op = vss_msg->vss_hdr.operation; 313 error = HV_S_OK; 314 315 switch (op) { 316 case VSS_OP_FREEZE: 317 case VSS_OP_THAW: 318 error = vss_operate(op); 319 syslog(LOG_INFO, "VSS: op=%s: %s\n", 320 op == VSS_OP_FREEZE ? "FREEZE" : "THAW", 321 error ? "failed" : "succeeded"); 322 323 if (error) { 324 error = HV_E_FAIL; 325 syslog(LOG_ERR, "op=%d failed!", op); 326 syslog(LOG_ERR, "report it with these files:"); 327 syslog(LOG_ERR, "/etc/fstab and /proc/mounts"); 328 } 329 break; 330 default: 331 syslog(LOG_ERR, "Illegal op:%d\n", op); 332 } 333 vss_msg->error = error; 334 len = netlink_send(fd, incoming_cn_msg); 335 if (len < 0) { 336 syslog(LOG_ERR, "net_link send failed; error:%d %s", 337 errno, strerror(errno)); 338 exit(EXIT_FAILURE); 339 } 340 } 341 342 } 343