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