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 char vss_recv_buffer[4096]; 42 static char vss_send_buffer[4096]; 43 static struct sockaddr_nl addr; 44 45 #ifndef SOL_NETLINK 46 #define SOL_NETLINK 270 47 #endif 48 49 50 static int vss_do_freeze(char *dir, unsigned int cmd, char *fs_op) 51 { 52 int ret, fd = open(dir, O_RDONLY); 53 54 if (fd < 0) 55 return 1; 56 ret = ioctl(fd, cmd, 0); 57 syslog(LOG_INFO, "VSS: %s of %s: %s\n", fs_op, dir, strerror(errno)); 58 close(fd); 59 return !!ret; 60 } 61 62 static int vss_operate(int operation) 63 { 64 char *fs_op; 65 char match[] = "/dev/"; 66 FILE *mounts; 67 struct mntent *ent; 68 unsigned int cmd; 69 int error = 0, root_seen = 0; 70 71 switch (operation) { 72 case VSS_OP_FREEZE: 73 cmd = FIFREEZE; 74 fs_op = "freeze"; 75 break; 76 case VSS_OP_THAW: 77 cmd = FITHAW; 78 fs_op = "thaw"; 79 break; 80 default: 81 return -1; 82 } 83 84 mounts = setmntent("/proc/mounts", "r"); 85 if (mounts == NULL) 86 return -1; 87 88 while ((ent = getmntent(mounts))) { 89 if (strncmp(ent->mnt_fsname, match, strlen(match))) 90 continue; 91 if (strcmp(ent->mnt_type, "iso9660") == 0) 92 continue; 93 if (strcmp(ent->mnt_dir, "/") == 0) { 94 root_seen = 1; 95 continue; 96 } 97 error |= vss_do_freeze(ent->mnt_dir, cmd, fs_op); 98 } 99 endmntent(mounts); 100 101 if (root_seen) { 102 error |= vss_do_freeze("/", cmd, fs_op); 103 } 104 105 return error; 106 } 107 108 static int netlink_send(int fd, struct cn_msg *msg) 109 { 110 struct nlmsghdr *nlh; 111 unsigned int size; 112 struct msghdr message; 113 char buffer[64]; 114 struct iovec iov[2]; 115 116 size = NLMSG_SPACE(sizeof(struct cn_msg) + msg->len); 117 118 nlh = (struct nlmsghdr *)buffer; 119 nlh->nlmsg_seq = 0; 120 nlh->nlmsg_pid = getpid(); 121 nlh->nlmsg_type = NLMSG_DONE; 122 nlh->nlmsg_len = NLMSG_LENGTH(size - sizeof(*nlh)); 123 nlh->nlmsg_flags = 0; 124 125 iov[0].iov_base = nlh; 126 iov[0].iov_len = sizeof(*nlh); 127 128 iov[1].iov_base = msg; 129 iov[1].iov_len = size; 130 131 memset(&message, 0, sizeof(message)); 132 message.msg_name = &addr; 133 message.msg_namelen = sizeof(addr); 134 message.msg_iov = iov; 135 message.msg_iovlen = 2; 136 137 return sendmsg(fd, &message, 0); 138 } 139 140 int main(void) 141 { 142 int fd, len, nl_group; 143 int error; 144 struct cn_msg *message; 145 struct pollfd pfd; 146 struct nlmsghdr *incoming_msg; 147 struct cn_msg *incoming_cn_msg; 148 int op; 149 struct hv_vss_msg *vss_msg; 150 151 if (daemon(1, 0)) 152 return 1; 153 154 openlog("Hyper-V VSS", 0, LOG_USER); 155 syslog(LOG_INFO, "VSS starting; pid is:%d", getpid()); 156 157 fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR); 158 if (fd < 0) { 159 syslog(LOG_ERR, "netlink socket creation failed; error:%d", fd); 160 exit(EXIT_FAILURE); 161 } 162 addr.nl_family = AF_NETLINK; 163 addr.nl_pad = 0; 164 addr.nl_pid = 0; 165 addr.nl_groups = 0; 166 167 168 error = bind(fd, (struct sockaddr *)&addr, sizeof(addr)); 169 if (error < 0) { 170 syslog(LOG_ERR, "bind failed; error:%d", error); 171 close(fd); 172 exit(EXIT_FAILURE); 173 } 174 nl_group = CN_VSS_IDX; 175 setsockopt(fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &nl_group, sizeof(nl_group)); 176 /* 177 * Register ourselves with the kernel. 178 */ 179 message = (struct cn_msg *)vss_send_buffer; 180 message->id.idx = CN_VSS_IDX; 181 message->id.val = CN_VSS_VAL; 182 message->ack = 0; 183 vss_msg = (struct hv_vss_msg *)message->data; 184 vss_msg->vss_hdr.operation = VSS_OP_REGISTER; 185 186 message->len = sizeof(struct hv_vss_msg); 187 188 len = netlink_send(fd, message); 189 if (len < 0) { 190 syslog(LOG_ERR, "netlink_send failed; error:%d", len); 191 close(fd); 192 exit(EXIT_FAILURE); 193 } 194 195 pfd.fd = fd; 196 197 while (1) { 198 struct sockaddr *addr_p = (struct sockaddr *) &addr; 199 socklen_t addr_l = sizeof(addr); 200 pfd.events = POLLIN; 201 pfd.revents = 0; 202 poll(&pfd, 1, -1); 203 204 len = recvfrom(fd, vss_recv_buffer, sizeof(vss_recv_buffer), 0, 205 addr_p, &addr_l); 206 207 if (len < 0) { 208 syslog(LOG_ERR, "recvfrom failed; pid:%u error:%d %s", 209 addr.nl_pid, errno, strerror(errno)); 210 close(fd); 211 return -1; 212 } 213 214 if (addr.nl_pid) { 215 syslog(LOG_WARNING, 216 "Received packet from untrusted pid:%u", 217 addr.nl_pid); 218 continue; 219 } 220 221 incoming_msg = (struct nlmsghdr *)vss_recv_buffer; 222 223 if (incoming_msg->nlmsg_type != NLMSG_DONE) 224 continue; 225 226 incoming_cn_msg = (struct cn_msg *)NLMSG_DATA(incoming_msg); 227 vss_msg = (struct hv_vss_msg *)incoming_cn_msg->data; 228 op = vss_msg->vss_hdr.operation; 229 error = HV_S_OK; 230 231 switch (op) { 232 case VSS_OP_FREEZE: 233 case VSS_OP_THAW: 234 error = vss_operate(op); 235 if (error) 236 error = HV_E_FAIL; 237 break; 238 default: 239 syslog(LOG_ERR, "Illegal op:%d\n", op); 240 } 241 vss_msg->error = error; 242 len = netlink_send(fd, incoming_cn_msg); 243 if (len < 0) { 244 syslog(LOG_ERR, "net_link send failed; error:%d", len); 245 exit(EXIT_FAILURE); 246 } 247 } 248 249 } 250