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_type, "vfat") == 0)
  91                         continue;
  92                 if (strcmp(ent->mnt_dir, "/") == 0) {
  93                         root_seen = 1;
  94                         continue;
  95                 }
  96                 error |= vss_do_freeze(ent->mnt_dir, cmd, fs_op);
  97         }
  98         endmntent(mounts);
  99
 100         if (root_seen) {
 101                 error |= vss_do_freeze("/", cmd, fs_op);
 102         }
 103
 104         return error;
 105 }
 106
 107 static int netlink_send(int fd, struct cn_msg *msg)
 108 {
 109         struct nlmsghdr nlh = { .nlmsg_type = NLMSG_DONE };
 110         unsigned int size;
 111         struct msghdr message;
 112         struct iovec iov[2];
 113
 114         size = sizeof(struct cn_msg) + msg->len;
 115
 116         nlh.nlmsg_pid = getpid();
 117         nlh.nlmsg_len = NLMSG_LENGTH(size);
 118
 119         iov[0].iov_base = &nlh;
 120         iov[0].iov_len = sizeof(nlh);
 121
 122         iov[1].iov_base = msg;
 123         iov[1].iov_len = size;
 124
 125         memset(&message, 0, sizeof(message));
 126         message.msg_name = &addr;
 127         message.msg_namelen = sizeof(addr);
 128         message.msg_iov = iov;
 129         message.msg_iovlen = 2;
 130
 131         return sendmsg(fd, &message, 0);
 132 }
 133
 134 int main(void)
 135 {
 136         int fd, len, nl_group;
 137         int error;
 138         struct cn_msg *message;
 139         struct pollfd pfd;
 140         struct nlmsghdr *incoming_msg;
 141         struct cn_msg   *incoming_cn_msg;
 142         int     op;
 143         struct hv_vss_msg *vss_msg;
 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_LENGTH(0) + sizeof(struct cn_msg) + sizeof(struct hv_vss_msg);
 154         vss_recv_buffer = calloc(1, vss_recv_buffer_len);
 155         if (!vss_recv_buffer) {
 156                 syslog(LOG_ERR, "Failed to allocate netlink buffers");
 157                 exit(EXIT_FAILURE);
 158         }
 159
 160         fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
 161         if (fd < 0) {
 162                 syslog(LOG_ERR, "netlink socket creation failed; error:%d %s",
 163                                 errno, strerror(errno));
 164                 exit(EXIT_FAILURE);
 165         }
 166         addr.nl_family = AF_NETLINK;
 167         addr.nl_pad = 0;
 168         addr.nl_pid = 0;
 169         addr.nl_groups = 0;
 170
 171
 172         error = bind(fd, (struct sockaddr *)&addr, sizeof(addr));
 173         if (error < 0) {
 174                 syslog(LOG_ERR, "bind failed; error:%d %s", errno, strerror(errno));
 175                 close(fd);
 176                 exit(EXIT_FAILURE);
 177         }
 178         nl_group = CN_VSS_IDX;
 179         if (setsockopt(fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &nl_group, sizeof(nl_group)) < 0) {
 180                 syslog(LOG_ERR, "setsockopt failed; error:%d %s", errno, strerror(errno));
 181                 close(fd);
 182                 exit(EXIT_FAILURE);
 183         }
 184         /*
 185          * Register ourselves with the kernel.
 186          */
 187         message = (struct cn_msg *)vss_recv_buffer;
 188         message->id.idx = CN_VSS_IDX;
 189         message->id.val = CN_VSS_VAL;
 190         message->ack = 0;
 191         vss_msg = (struct hv_vss_msg *)message->data;
 192         vss_msg->vss_hdr.operation = VSS_OP_REGISTER;
 193
 194         message->len = sizeof(struct hv_vss_msg);
 195
 196         len = netlink_send(fd, message);
 197         if (len < 0) {
 198                 syslog(LOG_ERR, "netlink_send failed; error:%d %s", errno, strerror(errno));
 199                 close(fd);
 200                 exit(EXIT_FAILURE);
 201         }
 202
 203         pfd.fd = fd;
 204
 205         while (1) {
 206                 struct sockaddr *addr_p = (struct sockaddr *) &addr;
 207                 socklen_t addr_l = sizeof(addr);
 208                 pfd.events = POLLIN;
 209                 pfd.revents = 0;
 210
 211                 if (poll(&pfd, 1, -1) < 0) {
 212                         syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno));
 213                         if (errno == EINVAL) {
 214                                 close(fd);
 215                                 exit(EXIT_FAILURE);
 216                         }
 217                         else
 218                                 continue;
 219                 }
 220
 221                 len = recvfrom(fd, vss_recv_buffer, vss_recv_buffer_len, 0,
 222                                 addr_p, &addr_l);
 223
 224                 if (len < 0) {
 225                         syslog(LOG_ERR, "recvfrom failed; pid:%u error:%d %s",
 226                                         addr.nl_pid, errno, strerror(errno));
 227                         close(fd);
 228                         return -1;
 229                 }
 230
 231                 if (addr.nl_pid) {
 232                         syslog(LOG_WARNING,
 233                                 "Received packet from untrusted pid:%u",
 234                                 addr.nl_pid);
 235                         continue;
 236                 }
 237
 238                 incoming_msg = (struct nlmsghdr *)vss_recv_buffer;
 239
 240                 if (incoming_msg->nlmsg_type != NLMSG_DONE)
 241                         continue;
 242
 243                 incoming_cn_msg = (struct cn_msg *)NLMSG_DATA(incoming_msg);
 244                 vss_msg = (struct hv_vss_msg *)incoming_cn_msg->data;
 245                 op = vss_msg->vss_hdr.operation;
 246                 error =  HV_S_OK;
 247
 248                 switch (op) {
 249                 case VSS_OP_FREEZE:
 250                 case VSS_OP_THAW:
 251                         error = vss_operate(op);
 252                         if (error)
 253                                 error = HV_E_FAIL;
 254                         break;
 255                 default:
 256                         syslog(LOG_ERR, "Illegal op:%d\n", op);
 257                 }
 258                 vss_msg->error = error;
 259                 len = netlink_send(fd, incoming_cn_msg);
 260                 if (len < 0) {
 261                         syslog(LOG_ERR, "net_link send failed; error:%d %s",
 262                                         errno, strerror(errno));
 263                         exit(EXIT_FAILURE);
 264                 }
 265         }
 266
 267 }