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 <linux/types.h> 26 #include <fcntl.h> 27 #include <stdio.h> 28 #include <mntent.h> 29 #include <stdlib.h> 30 #include <unistd.h> 31 #include <string.h> 32 #include <ctype.h> 33 #include <errno.h> 34 #include <arpa/inet.h> 35 #include <linux/fs.h> 36 #include <linux/connector.h> 37 #include <linux/hyperv.h> 38 #include <linux/netlink.h> 39 #include <syslog.h> 40 41 static struct sockaddr_nl addr; 42 43 #ifndef SOL_NETLINK 44 #define SOL_NETLINK 270 45 #endif 46 47 48 static int vss_do_freeze(char *dir, unsigned int cmd, char *fs_op) 49 { 50 int ret, fd = open(dir, O_RDONLY); 51 52 if (fd < 0) 53 return 1; 54 ret = ioctl(fd, cmd, 0); 55 syslog(LOG_INFO, "VSS: %s of %s: %s\n", fs_op, dir, strerror(errno)); 56 close(fd); 57 return !!ret; 58 } 59 60 static int vss_operate(int operation) 61 { 62 char *fs_op; 63 char match[] = "/dev/"; 64 FILE *mounts; 65 struct mntent *ent; 66 unsigned int cmd; 67 int error = 0, root_seen = 0; 68 69 switch (operation) { 70 case VSS_OP_FREEZE: 71 cmd = FIFREEZE; 72 fs_op = "freeze"; 73 break; 74 case VSS_OP_THAW: 75 cmd = FITHAW; 76 fs_op = "thaw"; 77 break; 78 default: 79 return -1; 80 } 81 82 mounts = setmntent("/proc/mounts", "r"); 83 if (mounts == NULL) 84 return -1; 85 86 while ((ent = getmntent(mounts))) { 87 if (strncmp(ent->mnt_fsname, match, strlen(match))) 88 continue; 89 if (strcmp(ent->mnt_type, "iso9660") == 0) 90 continue; 91 if (strcmp(ent->mnt_dir, "/") == 0) { 92 root_seen = 1; 93 continue; 94 } 95 error |= vss_do_freeze(ent->mnt_dir, cmd, fs_op); 96 } 97 endmntent(mounts); 98 99 if (root_seen) { 100 error |= vss_do_freeze("/", cmd, fs_op); 101 } 102 103 return error; 104 } 105 106 static int netlink_send(int fd, struct cn_msg *msg) 107 { 108 struct nlmsghdr nlh = { .nlmsg_type = NLMSG_DONE }; 109 unsigned int size; 110 struct msghdr message; 111 struct iovec iov[2]; 112 113 size = sizeof(struct cn_msg) + msg->len; 114 115 nlh.nlmsg_pid = getpid(); 116 nlh.nlmsg_len = NLMSG_LENGTH(size); 117 118 iov[0].iov_base = &nlh; 119 iov[0].iov_len = sizeof(nlh); 120 121 iov[1].iov_base = msg; 122 iov[1].iov_len = size; 123 124 memset(&message, 0, sizeof(message)); 125 message.msg_name = &addr; 126 message.msg_namelen = sizeof(addr); 127 message.msg_iov = iov; 128 message.msg_iovlen = 2; 129 130 return sendmsg(fd, &message, 0); 131 } 132 133 int main(void) 134 { 135 int fd, len, nl_group; 136 int error; 137 struct cn_msg *message; 138 struct pollfd pfd; 139 struct nlmsghdr *incoming_msg; 140 struct cn_msg *incoming_cn_msg; 141 int op; 142 struct hv_vss_msg *vss_msg; 143 char *vss_recv_buffer; 144 size_t vss_recv_buffer_len; 145 146 if (daemon(1, 0)) 147 return 1; 148 149 openlog("Hyper-V VSS", 0, LOG_USER); 150 syslog(LOG_INFO, "VSS starting; pid is:%d", getpid()); 151 152 vss_recv_buffer_len = NLMSG_LENGTH(0) + sizeof(struct cn_msg) + sizeof(struct hv_vss_msg); 153 vss_recv_buffer = calloc(1, vss_recv_buffer_len); 154 if (!vss_recv_buffer) { 155 syslog(LOG_ERR, "Failed to allocate netlink buffers"); 156 exit(EXIT_FAILURE); 157 } 158 159 fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR); 160 if (fd < 0) { 161 syslog(LOG_ERR, "netlink socket creation failed; error:%d %s", 162 errno, strerror(errno)); 163 exit(EXIT_FAILURE); 164 } 165 addr.nl_family = AF_NETLINK; 166 addr.nl_pad = 0; 167 addr.nl_pid = 0; 168 addr.nl_groups = 0; 169 170 171 error = bind(fd, (struct sockaddr *)&addr, sizeof(addr)); 172 if (error < 0) { 173 syslog(LOG_ERR, "bind failed; error:%d %s", errno, strerror(errno)); 174 close(fd); 175 exit(EXIT_FAILURE); 176 } 177 nl_group = CN_VSS_IDX; 178 if (setsockopt(fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &nl_group, sizeof(nl_group)) < 0) { 179 syslog(LOG_ERR, "setsockopt failed; error:%d %s", errno, strerror(errno)); 180 close(fd); 181 exit(EXIT_FAILURE); 182 } 183 /* 184 * Register ourselves with the kernel. 185 */ 186 message = (struct cn_msg *)vss_recv_buffer; 187 message->id.idx = CN_VSS_IDX; 188 message->id.val = CN_VSS_VAL; 189 message->ack = 0; 190 vss_msg = (struct hv_vss_msg *)message->data; 191 vss_msg->vss_hdr.operation = VSS_OP_REGISTER; 192 193 message->len = sizeof(struct hv_vss_msg); 194 195 len = netlink_send(fd, message); 196 if (len < 0) { 197 syslog(LOG_ERR, "netlink_send failed; error:%d %s", errno, strerror(errno)); 198 close(fd); 199 exit(EXIT_FAILURE); 200 } 201 202 pfd.fd = fd; 203 204 while (1) { 205 struct sockaddr *addr_p = (struct sockaddr *) &addr; 206 socklen_t addr_l = sizeof(addr); 207 pfd.events = POLLIN; 208 pfd.revents = 0; 209 210 if (poll(&pfd, 1, -1) < 0) { 211 syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno)); 212 if (errno == EINVAL) { 213 close(fd); 214 exit(EXIT_FAILURE); 215 } 216 else 217 continue; 218 } 219 220 len = recvfrom(fd, vss_recv_buffer, vss_recv_buffer_len, 0, 221 addr_p, &addr_l); 222 223 if (len < 0) { 224 syslog(LOG_ERR, "recvfrom failed; pid:%u error:%d %s", 225 addr.nl_pid, errno, strerror(errno)); 226 close(fd); 227 return -1; 228 } 229 230 if (addr.nl_pid) { 231 syslog(LOG_WARNING, 232 "Received packet from untrusted pid:%u", 233 addr.nl_pid); 234 continue; 235 } 236 237 incoming_msg = (struct nlmsghdr *)vss_recv_buffer; 238 239 if (incoming_msg->nlmsg_type != NLMSG_DONE) 240 continue; 241 242 incoming_cn_msg = (struct cn_msg *)NLMSG_DATA(incoming_msg); 243 vss_msg = (struct hv_vss_msg *)incoming_cn_msg->data; 244 op = vss_msg->vss_hdr.operation; 245 error = HV_S_OK; 246 247 switch (op) { 248 case VSS_OP_FREEZE: 249 case VSS_OP_THAW: 250 error = vss_operate(op); 251 if (error) 252 error = HV_E_FAIL; 253 break; 254 default: 255 syslog(LOG_ERR, "Illegal op:%d\n", op); 256 } 257 vss_msg->error = error; 258 len = netlink_send(fd, incoming_cn_msg); 259 if (len < 0) { 260 syslog(LOG_ERR, "net_link send failed; error:%d %s", 261 errno, strerror(errno)); 262 exit(EXIT_FAILURE); 263 } 264 } 265 266 } 267