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 40 static struct sockaddr_nl addr; 41 42 #ifndef SOL_NETLINK 43 #define SOL_NETLINK 270 44 #endif 45 46 47 static int vss_do_freeze(char *dir, unsigned int cmd, char *fs_op) 48 { 49 int ret, fd = open(dir, O_RDONLY); 50 51 if (fd < 0) 52 return 1; 53 ret = ioctl(fd, cmd, 0); 54 syslog(LOG_INFO, "VSS: %s of %s: %s\n", fs_op, dir, strerror(errno)); 55 close(fd); 56 return !!ret; 57 } 58 59 static int vss_operate(int operation) 60 { 61 char *fs_op; 62 char match[] = "/dev/"; 63 FILE *mounts; 64 struct mntent *ent; 65 unsigned int cmd; 66 int error = 0, root_seen = 0; 67 68 switch (operation) { 69 case VSS_OP_FREEZE: 70 cmd = FIFREEZE; 71 fs_op = "freeze"; 72 break; 73 case VSS_OP_THAW: 74 cmd = FITHAW; 75 fs_op = "thaw"; 76 break; 77 default: 78 return -1; 79 } 80 81 mounts = setmntent("/proc/mounts", "r"); 82 if (mounts == NULL) 83 return -1; 84 85 while ((ent = getmntent(mounts))) { 86 if (strncmp(ent->mnt_fsname, match, strlen(match))) 87 continue; 88 if (strcmp(ent->mnt_type, "iso9660") == 0) 89 continue; 90 if (strcmp(ent->mnt_type, "vfat") == 0) 91 continue; 92 if (strcmp(ent->mnt_dir, "/") == 0) { 93 root_seen = 1; 94 continue; 95 } 96 error |= vss_do_freeze(ent->mnt_dir, cmd, fs_op); 97 } 98 endmntent(mounts); 99 100 if (root_seen) { 101 error |= vss_do_freeze("/", cmd, fs_op); 102 } 103 104 return error; 105 } 106 107 static int netlink_send(int fd, struct cn_msg *msg) 108 { 109 struct nlmsghdr nlh = { .nlmsg_type = NLMSG_DONE }; 110 unsigned int size; 111 struct msghdr message; 112 struct iovec iov[2]; 113 114 size = sizeof(struct cn_msg) + msg->len; 115 116 nlh.nlmsg_pid = getpid(); 117 nlh.nlmsg_len = NLMSG_LENGTH(size); 118 119 iov[0].iov_base = &nlh; 120 iov[0].iov_len = sizeof(nlh); 121 122 iov[1].iov_base = msg; 123 iov[1].iov_len = size; 124 125 memset(&message, 0, sizeof(message)); 126 message.msg_name = &addr; 127 message.msg_namelen = sizeof(addr); 128 message.msg_iov = iov; 129 message.msg_iovlen = 2; 130 131 return sendmsg(fd, &message, 0); 132 } 133 134 int main(void) 135 { 136 int fd, len, nl_group; 137 int error; 138 struct cn_msg *message; 139 struct pollfd pfd; 140 struct nlmsghdr *incoming_msg; 141 struct cn_msg *incoming_cn_msg; 142 int op; 143 struct hv_vss_msg *vss_msg; 144 char *vss_recv_buffer; 145 size_t vss_recv_buffer_len; 146 147 if (daemon(1, 0)) 148 return 1; 149 150 openlog("Hyper-V VSS", 0, LOG_USER); 151 syslog(LOG_INFO, "VSS starting; pid is:%d", getpid()); 152 153 vss_recv_buffer_len = NLMSG_LENGTH(0) + sizeof(struct cn_msg) + sizeof(struct hv_vss_msg); 154 vss_recv_buffer = calloc(1, vss_recv_buffer_len); 155 if (!vss_recv_buffer) { 156 syslog(LOG_ERR, "Failed to allocate netlink buffers"); 157 exit(EXIT_FAILURE); 158 } 159 160 fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR); 161 if (fd < 0) { 162 syslog(LOG_ERR, "netlink socket creation failed; error:%d %s", 163 errno, strerror(errno)); 164 exit(EXIT_FAILURE); 165 } 166 addr.nl_family = AF_NETLINK; 167 addr.nl_pad = 0; 168 addr.nl_pid = 0; 169 addr.nl_groups = 0; 170 171 172 error = bind(fd, (struct sockaddr *)&addr, sizeof(addr)); 173 if (error < 0) { 174 syslog(LOG_ERR, "bind failed; error:%d %s", errno, strerror(errno)); 175 close(fd); 176 exit(EXIT_FAILURE); 177 } 178 nl_group = CN_VSS_IDX; 179 if (setsockopt(fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &nl_group, sizeof(nl_group)) < 0) { 180 syslog(LOG_ERR, "setsockopt failed; error:%d %s", errno, strerror(errno)); 181 close(fd); 182 exit(EXIT_FAILURE); 183 } 184 /* 185 * Register ourselves with the kernel. 186 */ 187 message = (struct cn_msg *)vss_recv_buffer; 188 message->id.idx = CN_VSS_IDX; 189 message->id.val = CN_VSS_VAL; 190 message->ack = 0; 191 vss_msg = (struct hv_vss_msg *)message->data; 192 vss_msg->vss_hdr.operation = VSS_OP_REGISTER; 193 194 message->len = sizeof(struct hv_vss_msg); 195 196 len = netlink_send(fd, message); 197 if (len < 0) { 198 syslog(LOG_ERR, "netlink_send failed; error:%d %s", errno, strerror(errno)); 199 close(fd); 200 exit(EXIT_FAILURE); 201 } 202 203 pfd.fd = fd; 204 205 while (1) { 206 struct sockaddr *addr_p = (struct sockaddr *) &addr; 207 socklen_t addr_l = sizeof(addr); 208 pfd.events = POLLIN; 209 pfd.revents = 0; 210 211 if (poll(&pfd, 1, -1) < 0) { 212 syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno)); 213 if (errno == EINVAL) { 214 close(fd); 215 exit(EXIT_FAILURE); 216 } 217 else 218 continue; 219 } 220 221 len = recvfrom(fd, vss_recv_buffer, vss_recv_buffer_len, 0, 222 addr_p, &addr_l); 223 224 if (len < 0) { 225 syslog(LOG_ERR, "recvfrom failed; pid:%u error:%d %s", 226 addr.nl_pid, errno, strerror(errno)); 227 close(fd); 228 return -1; 229 } 230 231 if (addr.nl_pid) { 232 syslog(LOG_WARNING, 233 "Received packet from untrusted pid:%u", 234 addr.nl_pid); 235 continue; 236 } 237 238 incoming_msg = (struct nlmsghdr *)vss_recv_buffer; 239 240 if (incoming_msg->nlmsg_type != NLMSG_DONE) 241 continue; 242 243 incoming_cn_msg = (struct cn_msg *)NLMSG_DATA(incoming_msg); 244 vss_msg = (struct hv_vss_msg *)incoming_cn_msg->data; 245 op = vss_msg->vss_hdr.operation; 246 error = HV_S_OK; 247 248 switch (op) { 249 case VSS_OP_FREEZE: 250 case VSS_OP_THAW: 251 error = vss_operate(op); 252 if (error) 253 error = HV_E_FAIL; 254 break; 255 default: 256 syslog(LOG_ERR, "Illegal op:%d\n", op); 257 } 258 vss_msg->error = error; 259 len = netlink_send(fd, incoming_cn_msg); 260 if (len < 0) { 261 syslog(LOG_ERR, "net_link send failed; error:%d %s", 262 errno, strerror(errno)); 263 exit(EXIT_FAILURE); 264 } 265 } 266 267 } 268