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 <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_send_buffer;
 144         char *vss_recv_buffer;
 145         size_t vss_recv_buffer_len;
 146
 147         if (daemon(1, 0))
 148                 return 1;
 149
 150         openlog("Hyper-V VSS", 0, LOG_USER);
 151         syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());
 152
 153         vss_recv_buffer_len = NLMSG_HDRLEN + sizeof(struct cn_msg) + sizeof(struct hv_vss_msg);
 154         vss_send_buffer = calloc(1, vss_recv_buffer_len);
 155         vss_recv_buffer = calloc(1, vss_recv_buffer_len);
 156         if (!(vss_send_buffer && vss_recv_buffer)) {
 157                 syslog(LOG_ERR, "Failed to allocate netlink buffers");
 158                 exit(EXIT_FAILURE);
 159         }
 160
 161         fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
 162         if (fd < 0) {
 163                 syslog(LOG_ERR, "netlink socket creation failed; error:%d %s",
 164                                 errno, strerror(errno));
 165                 exit(EXIT_FAILURE);
 166         }
 167         addr.nl_family = AF_NETLINK;
 168         addr.nl_pad = 0;
 169         addr.nl_pid = 0;
 170         addr.nl_groups = 0;
 171
 172
 173         error = bind(fd, (struct sockaddr *)&addr, sizeof(addr));
 174         if (error < 0) {
 175                 syslog(LOG_ERR, "bind failed; error:%d %s", errno, strerror(errno));
 176                 close(fd);
 177                 exit(EXIT_FAILURE);
 178         }
 179         nl_group = CN_VSS_IDX;
 180         if (setsockopt(fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &nl_group, sizeof(nl_group)) < 0) {
 181                 syslog(LOG_ERR, "setsockopt failed; error:%d %s", errno, strerror(errno));
 182                 close(fd);
 183                 exit(EXIT_FAILURE);
 184         }
 185         /*
 186          * Register ourselves with the kernel.
 187          */
 188         message = (struct cn_msg *)vss_send_buffer;
 189         message->id.idx = CN_VSS_IDX;
 190         message->id.val = CN_VSS_VAL;
 191         message->ack = 0;
 192         vss_msg = (struct hv_vss_msg *)message->data;
 193         vss_msg->vss_hdr.operation = VSS_OP_REGISTER;
 194
 195         message->len = sizeof(struct hv_vss_msg);
 196
 197         len = netlink_send(fd, message);
 198         if (len < 0) {
 199                 syslog(LOG_ERR, "netlink_send failed; error:%d %s", errno, strerror(errno));
 200                 close(fd);
 201                 exit(EXIT_FAILURE);
 202         }
 203
 204         pfd.fd = fd;
 205
 206         while (1) {
 207                 struct sockaddr *addr_p = (struct sockaddr *) &addr;
 208                 socklen_t addr_l = sizeof(addr);
 209                 pfd.events = POLLIN;
 210                 pfd.revents = 0;
 211
 212                 if (poll(&pfd, 1, -1) < 0) {
 213                         syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno));
 214                         if (errno == EINVAL) {
 215                                 close(fd);
 216                                 exit(EXIT_FAILURE);
 217                         }
 218                         else
 219                                 continue;
 220                 }
 221
 222                 len = recvfrom(fd, vss_recv_buffer, vss_recv_buffer_len, 0,
 223                                 addr_p, &addr_l);
 224
 225                 if (len < 0) {
 226                         syslog(LOG_ERR, "recvfrom failed; pid:%u error:%d %s",
 227                                         addr.nl_pid, errno, strerror(errno));
 228                         close(fd);
 229                         return -1;
 230                 }
 231
 232                 if (addr.nl_pid) {
 233                         syslog(LOG_WARNING,
 234                                 "Received packet from untrusted pid:%u",
 235                                 addr.nl_pid);
 236                         continue;
 237                 }
 238
 239                 incoming_msg = (struct nlmsghdr *)vss_recv_buffer;
 240
 241                 if (incoming_msg->nlmsg_type != NLMSG_DONE)
 242                         continue;
 243
 244                 incoming_cn_msg = (struct cn_msg *)NLMSG_DATA(incoming_msg);
 245                 vss_msg = (struct hv_vss_msg *)incoming_cn_msg->data;
 246                 op = vss_msg->vss_hdr.operation;
 247                 error =  HV_S_OK;
 248
 249                 switch (op) {
 250                 case VSS_OP_FREEZE:
 251                 case VSS_OP_THAW:
 252                         error = vss_operate(op);
 253                         if (error)
 254                                 error = HV_E_FAIL;
 255                         break;
 256                 default:
 257                         syslog(LOG_ERR, "Illegal op:%d\n", op);
 258                 }
 259                 vss_msg->error = error;
 260                 len = netlink_send(fd, incoming_cn_msg);
 261                 if (len < 0) {
 262                         syslog(LOG_ERR, "net_link send failed; error:%d %s",
 263                                         errno, strerror(errno));
 264                         exit(EXIT_FAILURE);
 265                 }
 266         }
 267
 268 }