tools/hv/hv_vss_daemon.c

   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 <linux/types.h>
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <unistd.h>
  28 #include <string.h>
  29 #include <ctype.h>
  30 #include <errno.h>
  31 #include <arpa/inet.h>
  32 #include <linux/connector.h>
  33 #include <linux/hyperv.h>
  34 #include <linux/netlink.h>
  35 #include <syslog.h>
  36
  37 static char vss_recv_buffer[4096];
  38 static char vss_send_buffer[4096];
  39 static struct sockaddr_nl addr;
  40
  41 #ifndef SOL_NETLINK
  42 #define SOL_NETLINK 270
  43 #endif
  44
  45
  46 static int vss_operate(int operation)
  47 {
  48         char *fs_op;
  49         char cmd[512];
  50         char buf[512];
  51         FILE *file;
  52         char *p;
  53         char *x;
  54         int error = 0;
  55
  56         switch (operation) {
  57         case VSS_OP_FREEZE:
  58                 fs_op = "-f ";
  59                 break;
  60         case VSS_OP_THAW:
  61                 fs_op = "-u ";
  62                 break;
  63         default:
  64                 return -1;
  65         }
  66
  67         file = popen("mount | awk '/^\\/dev\\// { print $3}'", "r");
  68         if (file == NULL)
  69                 return -1;
  70
  71         while ((p = fgets(buf, sizeof(buf), file)) != NULL) {
  72                 x = strchr(p, '\n');
  73                 *x = '\0';
  74                 if (!strncmp(p, "/", sizeof("/")))
  75                         continue;
  76
  77                 sprintf(cmd, "%s %s %s", "fsfreeze ", fs_op, p);
  78                 syslog(LOG_INFO, "VSS cmd is %s\n", cmd);
  79                 error = system(cmd);
  80         }
  81         pclose(file);
  82
  83         sprintf(cmd, "%s %s %s", "fsfreeze ", fs_op, "/");
  84         syslog(LOG_INFO, "VSS cmd is %s\n", cmd);
  85         error = system(cmd);
  86
  87         return error;
  88 }
  89
  90 static int netlink_send(int fd, struct cn_msg *msg)
  91 {
  92         struct nlmsghdr *nlh;
  93         unsigned int size;
  94         struct msghdr message;
  95         char buffer[64];
  96         struct iovec iov[2];
  97
  98         size = NLMSG_SPACE(sizeof(struct cn_msg) + msg->len);
  99
 100         nlh = (struct nlmsghdr *)buffer;
 101         nlh->nlmsg_seq = 0;
 102         nlh->nlmsg_pid = getpid();
 103         nlh->nlmsg_type = NLMSG_DONE;
 104         nlh->nlmsg_len = NLMSG_LENGTH(size - sizeof(*nlh));
 105         nlh->nlmsg_flags = 0;
 106
 107         iov[0].iov_base = nlh;
 108         iov[0].iov_len = sizeof(*nlh);
 109
 110         iov[1].iov_base = msg;
 111         iov[1].iov_len = size;
 112
 113         memset(&message, 0, sizeof(message));
 114         message.msg_name = &addr;
 115         message.msg_namelen = sizeof(addr);
 116         message.msg_iov = iov;
 117         message.msg_iovlen = 2;
 118
 119         return sendmsg(fd, &message, 0);
 120 }
 121
 122 int main(void)
 123 {
 124         int fd, len, nl_group;
 125         int error;
 126         struct cn_msg *message;
 127         struct pollfd pfd;
 128         struct nlmsghdr *incoming_msg;
 129         struct cn_msg   *incoming_cn_msg;
 130         int     op;
 131         struct hv_vss_msg *vss_msg;
 132
 133         if (daemon(1, 0))
 134                 return 1;
 135
 136         openlog("Hyper-V VSS", 0, LOG_USER);
 137         syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());
 138
 139         fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
 140         if (fd < 0) {
 141                 syslog(LOG_ERR, "netlink socket creation failed; error:%d", fd);
 142                 exit(EXIT_FAILURE);
 143         }
 144         addr.nl_family = AF_NETLINK;
 145         addr.nl_pad = 0;
 146         addr.nl_pid = 0;
 147         addr.nl_groups = 0;
 148
 149
 150         error = bind(fd, (struct sockaddr *)&addr, sizeof(addr));
 151         if (error < 0) {
 152                 syslog(LOG_ERR, "bind failed; error:%d", error);
 153                 close(fd);
 154                 exit(EXIT_FAILURE);
 155         }
 156         nl_group = CN_VSS_IDX;
 157         setsockopt(fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &nl_group, sizeof(nl_group));
 158         /*
 159          * Register ourselves with the kernel.
 160          */
 161         message = (struct cn_msg *)vss_send_buffer;
 162         message->id.idx = CN_VSS_IDX;
 163         message->id.val = CN_VSS_VAL;
 164         message->ack = 0;
 165         vss_msg = (struct hv_vss_msg *)message->data;
 166         vss_msg->vss_hdr.operation = VSS_OP_REGISTER;
 167
 168         message->len = sizeof(struct hv_vss_msg);
 169
 170         len = netlink_send(fd, message);
 171         if (len < 0) {
 172                 syslog(LOG_ERR, "netlink_send failed; error:%d", len);
 173                 close(fd);
 174                 exit(EXIT_FAILURE);
 175         }
 176
 177         pfd.fd = fd;
 178
 179         while (1) {
 180                 struct sockaddr *addr_p = (struct sockaddr *) &addr;
 181                 socklen_t addr_l = sizeof(addr);
 182                 pfd.events = POLLIN;
 183                 pfd.revents = 0;
 184                 poll(&pfd, 1, -1);
 185
 186                 len = recvfrom(fd, vss_recv_buffer, sizeof(vss_recv_buffer), 0,
 187                                 addr_p, &addr_l);
 188
 189                 if (len < 0) {
 190                         syslog(LOG_ERR, "recvfrom failed; pid:%u error:%d %s",
 191                                         addr.nl_pid, errno, strerror(errno));
 192                         close(fd);
 193                         return -1;
 194                 }
 195
 196                 if (addr.nl_pid) {
 197                         syslog(LOG_WARNING, "Received packet from untrusted pid:%u",
 198                                         addr.nl_pid);
 199                         continue;
 200                 }
 201
 202                 incoming_msg = (struct nlmsghdr *)vss_recv_buffer;
 203
 204                 if (incoming_msg->nlmsg_type != NLMSG_DONE)
 205                         continue;
 206
 207                 incoming_cn_msg = (struct cn_msg *)NLMSG_DATA(incoming_msg);
 208                 vss_msg = (struct hv_vss_msg *)incoming_cn_msg->data;
 209                 op = vss_msg->vss_hdr.operation;
 210                 error =  HV_S_OK;
 211
 212                 switch (op) {
 213                 case VSS_OP_FREEZE:
 214                 case VSS_OP_THAW:
 215                         error = vss_operate(op);
 216                         if (error)
 217                                 error = HV_E_FAIL;
 218                         break;
 219                 default:
 220                         syslog(LOG_ERR, "Illegal op:%d\n", op);
 221                 }
 222                 vss_msg->error = error;
 223                 len = netlink_send(fd, incoming_cn_msg);
 224                 if (len < 0) {
 225                         syslog(LOG_ERR, "net_link send failed; error:%d", len);
 226                         exit(EXIT_FAILURE);
 227                 }
 228         }
 229
 230 }