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_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 }