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 <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 }