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 unsigned int cmd; 85 int error = 0, root_seen = 0, save_errno = 0; 86 87 switch (operation) { 88 case VSS_OP_FREEZE: 89 cmd = FIFREEZE; 90 break; 91 case VSS_OP_THAW: 92 cmd = FITHAW; 93 break; 94 default: 95 return -1; 96 } 97 98 mounts = setmntent("/proc/mounts", "r"); 99 if (mounts == NULL) 100 return -1; 101 102 while ((ent = getmntent(mounts))) { 103 if (strncmp(ent->mnt_fsname, match, strlen(match))) 104 continue; 105 if (hasmntopt(ent, MNTOPT_RO) != NULL) 106 continue; 107 if (strcmp(ent->mnt_type, "vfat") == 0) 108 continue; 109 if (strcmp(ent->mnt_dir, "/") == 0) { 110 root_seen = 1; 111 continue; 112 } 113 error |= vss_do_freeze(ent->mnt_dir, cmd); 114 if (error && operation == VSS_OP_FREEZE) 115 goto err; 116 } 117 118 if (root_seen) { 119 error |= vss_do_freeze("/", cmd); 120 if (error && operation == VSS_OP_FREEZE) 121 goto err; 122 } 123 124 goto out; 125 err: 126 save_errno = errno; 127 vss_operate(VSS_OP_THAW); 128 /* Call syslog after we thaw all filesystems */ 129 if (ent) 130 syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s", 131 ent->mnt_dir, save_errno, strerror(save_errno)); 132 else 133 syslog(LOG_ERR, "FREEZE of / failed; error:%d %s", save_errno, 134 strerror(save_errno)); 135 out: 136 endmntent(mounts); 137 return error; 138 } 139 140 static int netlink_send(int fd, struct cn_msg *msg) 141 { 142 struct nlmsghdr nlh = { .nlmsg_type = NLMSG_DONE }; 143 unsigned int size; 144 struct msghdr message; 145 struct iovec iov[2]; 146 147 size = sizeof(struct cn_msg) + msg->len; 148 149 nlh.nlmsg_pid = getpid(); 150 nlh.nlmsg_len = NLMSG_LENGTH(size); 151 152 iov[0].iov_base = &nlh; 153 iov[0].iov_len = sizeof(nlh); 154 155 iov[1].iov_base = msg; 156 iov[1].iov_len = size; 157 158 memset(&message, 0, sizeof(message)); 159 message.msg_name = &addr; 160 message.msg_namelen = sizeof(addr); 161 message.msg_iov = iov; 162 message.msg_iovlen = 2; 163 164 return sendmsg(fd, &message, 0); 165 } 166 167 void print_usage(char *argv[]) 168 { 169 fprintf(stderr, "Usage: %s [options]\n" 170 "Options are:\n" 171 " -n, --no-daemon stay in foreground, don't daemonize\n" 172 " -h, --help print this help\n", argv[0]); 173 } 174 175 int main(int argc, char *argv[]) 176 { 177 int fd, len, nl_group; 178 int error; 179 struct cn_msg *message; 180 struct pollfd pfd; 181 struct nlmsghdr *incoming_msg; 182 struct cn_msg *incoming_cn_msg; 183 int op; 184 struct hv_vss_msg *vss_msg; 185 char *vss_recv_buffer; 186 size_t vss_recv_buffer_len; 187 int daemonize = 1, long_index = 0, opt; 188 189 static struct option long_options[] = { 190 {"help", no_argument, 0, 'h' }, 191 {"no-daemon", no_argument, 0, 'n' }, 192 {0, 0, 0, 0 } 193 }; 194 195 while ((opt = getopt_long(argc, argv, "hn", long_options, 196 &long_index)) != -1) { 197 switch (opt) { 198 case 'n': 199 daemonize = 0; 200 break; 201 case 'h': 202 default: 203 print_usage(argv); 204 exit(EXIT_FAILURE); 205 } 206 } 207 208 if (daemonize && daemon(1, 0)) 209 return 1; 210 211 openlog("Hyper-V VSS", 0, LOG_USER); 212 syslog(LOG_INFO, "VSS starting; pid is:%d", getpid()); 213 214 vss_recv_buffer_len = NLMSG_LENGTH(0) + sizeof(struct cn_msg) + sizeof(struct hv_vss_msg); 215 vss_recv_buffer = calloc(1, vss_recv_buffer_len); 216 if (!vss_recv_buffer) { 217 syslog(LOG_ERR, "Failed to allocate netlink buffers"); 218 exit(EXIT_FAILURE); 219 } 220 221 fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR); 222 if (fd < 0) { 223 syslog(LOG_ERR, "netlink socket creation failed; error:%d %s", 224 errno, strerror(errno)); 225 exit(EXIT_FAILURE); 226 } 227 addr.nl_family = AF_NETLINK; 228 addr.nl_pad = 0; 229 addr.nl_pid = 0; 230 addr.nl_groups = 0; 231 232 233 error = bind(fd, (struct sockaddr *)&addr, sizeof(addr)); 234 if (error < 0) { 235 syslog(LOG_ERR, "bind failed; error:%d %s", errno, strerror(errno)); 236 close(fd); 237 exit(EXIT_FAILURE); 238 } 239 nl_group = CN_VSS_IDX; 240 if (setsockopt(fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &nl_group, sizeof(nl_group)) < 0) { 241 syslog(LOG_ERR, "setsockopt failed; error:%d %s", errno, strerror(errno)); 242 close(fd); 243 exit(EXIT_FAILURE); 244 } 245 /* 246 * Register ourselves with the kernel. 247 */ 248 message = (struct cn_msg *)vss_recv_buffer; 249 message->id.idx = CN_VSS_IDX; 250 message->id.val = CN_VSS_VAL; 251 message->ack = 0; 252 vss_msg = (struct hv_vss_msg *)message->data; 253 vss_msg->vss_hdr.operation = VSS_OP_REGISTER; 254 255 message->len = sizeof(struct hv_vss_msg); 256 257 len = netlink_send(fd, message); 258 if (len < 0) { 259 syslog(LOG_ERR, "netlink_send failed; error:%d %s", errno, strerror(errno)); 260 close(fd); 261 exit(EXIT_FAILURE); 262 } 263 264 pfd.fd = fd; 265 266 while (1) { 267 struct sockaddr *addr_p = (struct sockaddr *) &addr; 268 socklen_t addr_l = sizeof(addr); 269 pfd.events = POLLIN; 270 pfd.revents = 0; 271 272 if (poll(&pfd, 1, -1) < 0) { 273 syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno)); 274 if (errno == EINVAL) { 275 close(fd); 276 exit(EXIT_FAILURE); 277 } 278 else 279 continue; 280 } 281 282 len = recvfrom(fd, vss_recv_buffer, vss_recv_buffer_len, 0, 283 addr_p, &addr_l); 284 285 if (len < 0) { 286 syslog(LOG_ERR, "recvfrom failed; pid:%u error:%d %s", 287 addr.nl_pid, errno, strerror(errno)); 288 close(fd); 289 return -1; 290 } 291 292 if (addr.nl_pid) { 293 syslog(LOG_WARNING, 294 "Received packet from untrusted pid:%u", 295 addr.nl_pid); 296 continue; 297 } 298 299 incoming_msg = (struct nlmsghdr *)vss_recv_buffer; 300 301 if (incoming_msg->nlmsg_type != NLMSG_DONE) 302 continue; 303 304 incoming_cn_msg = (struct cn_msg *)NLMSG_DATA(incoming_msg); 305 vss_msg = (struct hv_vss_msg *)incoming_cn_msg->data; 306 op = vss_msg->vss_hdr.operation; 307 error = HV_S_OK; 308 309 switch (op) { 310 case VSS_OP_FREEZE: 311 case VSS_OP_THAW: 312 error = vss_operate(op); 313 syslog(LOG_INFO, "VSS: op=%s: %s\n", 314 op == VSS_OP_FREEZE ? "FREEZE" : "THAW", 315 error ? "failed" : "succeeded"); 316 317 if (error) { 318 error = HV_E_FAIL; 319 syslog(LOG_ERR, "op=%d failed!", op); 320 syslog(LOG_ERR, "report it with these files:"); 321 syslog(LOG_ERR, "/etc/fstab and /proc/mounts"); 322 } 323 break; 324 default: 325 syslog(LOG_ERR, "Illegal op:%d\n", op); 326 } 327 vss_msg->error = error; 328 len = netlink_send(fd, incoming_cn_msg); 329 if (len < 0) { 330 syslog(LOG_ERR, "net_link send failed; error:%d %s", 331 errno, strerror(errno)); 332 exit(EXIT_FAILURE); 333 } 334 } 335 336 } 337