autofs.c

   1 #include <sys/types.h>
   2 #include <linux/types.h>
   3 #include <paths.h>
   4 #include <limits.h>
   5 #include <time.h>
   6
   7 #include <stdio.h>
   8 #include <signal.h>
   9 #include <stdlib.h>
  10 #include <fcntl.h>
  11
  12 #include <errno.h>
  13
  14 #include <string.h>
  15 #include <syslog.h>
  16 #include <unistd.h>
  17 #include <sys/ioctl.h>
  18 #include <sys/types.h>
  19 #include <sys/wait.h>
  20 #include <sys/stat.h>
  21 #include <sys/time.h>
  22 #include <poll.h>
  23 #include <linux/auto_fs4.h>
  24
  25 #include "include/log.h"
  26 #include "include/sys.h"
  27 #include "include/timer.h"
  28 #include "include/mount.h"
  29 #include "include/signal.h"
  30 #include "include/ucix.h"
  31 #include "include/autofs.h"
  32
  33 int fdin = 0; /* data coming out of the kernel */
  34 int fdout = 0;/* data going into the kernel */
  35 dev_t dev;
  36
  37 time_t uci_timeout;
  38 char uci_path[32];
  39
  40 static void umount_autofs(void)
  41 {
  42         system_printf("umount %s 2> /dev/null", "/tmp/run/mountd/");
  43 }
  44
  45 static int mount_autofs(void)
  46 {
  47         int pipefd[2];
  48         struct stat st;
  49         log_printf("trying to mount %s as the autofs root\n", "/tmp/run/mountd/");
  50         if(is_mounted(0, "/tmp/run/mountd/"))
  51         {
  52                 log_printf("%s is already mounted\n", "/tmp/run/mountd/");
  53                 return -1;
  54         }
  55         fdout = fdin = -1;
  56         mkdir("/tmp/run/mountd/", 0555);
  57         if(pipe(pipefd) < 0)
  58         {
  59                 log_printf("failed to get kernel pipe\n");
  60                 return -1;
  61         }
  62         if(system_printf("/bin/mount -t autofs -o fd=%d,pgrp=%u,minproto=5,maxproto=5 \"mountd(pid%u)\" %s",
  63                 pipefd[1], (unsigned) getpgrp(), getpid(), "/tmp/run/mountd/") != 0)
  64         {
  65                 log_printf("unable to mount autofs on %s\n", "/tmp/run/mountd/");
  66                 close(pipefd[0]);
  67                 close(pipefd[1]);
  68                 return -1;
  69         }
  70
  71         close(pipefd[1]);
  72         fdout = pipefd[0];
  73
  74         fdin = open("/tmp/run/mountd/", O_RDONLY);
  75         if(fdin < 0)
  76         {
  77                 umount_autofs();
  78                 return -1;
  79         }
  80         stat("/tmp/run/mountd/", &st);
  81         return 0;
  82 }
  83
  84 static void send_ready(unsigned int wait_queue_token)
  85 {
  86         if(ioctl(fdin, AUTOFS_IOC_READY, wait_queue_token) < 0)
  87                 log_printf("failed to report ready to kernel\n");
  88 }
  89
  90 static void send_fail(unsigned int wait_queue_token)
  91 {
  92         if(ioctl(fdin, AUTOFS_IOC_FAIL, wait_queue_token) < 0)
  93                 log_printf("failed to report fail to kernel\n");
  94 }
  95
  96 static int autofs_process_request(const struct autofs_v5_packet *pkt)
  97 {
  98         struct stat st;
  99         log_printf("kernel is requesting a mount -> %s\n", pkt->name);
 100         chdir("/tmp/run/mountd/");
 101         if (lstat(pkt->name, &st) == -1 || (S_ISDIR(st.st_mode) && st.st_dev == dev)) {
 102                 if(!mount_new("/tmp/run/mountd/", (char*)pkt->name))
 103                 {
 104                         send_ready(pkt->wait_queue_token);
 105                 } else {
 106                         send_fail(pkt->wait_queue_token);
 107                         log_printf("failed to mount %s\n", pkt->name);
 108                 }
 109         } else {
 110                 send_ready(pkt->wait_queue_token);
 111         }
 112         chdir("/");
 113
 114         return 0;
 115 }
 116
 117 static void expire_proc(void)
 118 {
 119         struct autofs_packet_expire pkt;
 120         while(ioctl(fdin, AUTOFS_IOC_EXPIRE, &pkt) == 0)
 121                 mount_remove("/tmp/run/mountd/", pkt.name);
 122 }
 123
 124 static int fullread(void *ptr, size_t len)
 125 {
 126         char *buf = (char *) ptr;
 127         while(len > 0)
 128         {
 129                 ssize_t r = read(fdout, buf, len);
 130                 if(r == -1)
 131                 {
 132                         if (errno == EINTR)
 133                                 continue;
 134                         break;
 135                 }
 136                 buf += r;
 137                 len -= r;
 138         }
 139         return len;
 140 }
 141
 142 static int autofs_in(union autofs_v5_packet_union *pkt)
 143 {
 144         int res;
 145         struct pollfd fds[1];
 146
 147         fds[0].fd = fdout;
 148         fds[0].events = POLLIN;
 149
 150         while(1)
 151         {
 152                 res = poll(fds, 1, -1);
 153
 154                 if (res == -1)
 155                 {
 156                         if (errno == EINTR)
 157                                 continue;
 158                         log_printf("failed while trying to read packet from kernel\n");
 159                         return -1;
 160                 }
 161                 else if ((res > 0) && (fds[0].revents & POLLIN))
 162                 {
 163                         return fullread(pkt, sizeof(*pkt));
 164                 }
 165         }
 166 }
 167
 168 pid_t autofs_safe_fork(void)
 169 {
 170         pid_t pid = fork();
 171         if(!pid)
 172         {
 173                 close(fdin);
 174             close(fdout);
 175         }
 176         return pid;
 177 }
 178
 179 static void autofs_cleanup_handler(void)
 180 {
 181         close(fdin);
 182         close(fdout);
 183         umount_autofs();
 184 }
 185
 186 static void autofs_init(void)
 187 {
 188         int kproto_version;
 189         char *p;
 190         struct uci_context *ctx;
 191         signal_init(autofs_cleanup_handler);
 192         ctx = ucix_init("mountd");
 193         uci_timeout = ucix_get_option_int(ctx, "mountd", "mountd", "timeout", 60);
 194         p = ucix_get_option(ctx, "mountd", "mountd", "path");
 195         ucix_cleanup(ctx);
 196         if(p)
 197                 snprintf(uci_path, 31, p);
 198         else
 199                 snprintf(uci_path, 31, "/tmp/mounts/");
 200         uci_path[31] = '\0';
 201         mkdir("/tmp/run/", 0555);
 202         mkdir("/tmp/mounts", 0555);
 203         system_printf("rm -rf %s*", uci_path);
 204         if(uci_timeout < 16)
 205                 uci_timeout = 16;
 206         umount_autofs();
 207         mount_init();
 208         if(mount_autofs() < 0)
 209         {
 210                 closelog();
 211                 exit(1);
 212         }
 213         ioctl(fdin, AUTOFS_IOC_PROTOVER, &kproto_version);
 214         if(kproto_version != 5)
 215         {
 216                 log_printf("only kernel protocol version 5 is tested. You have %d.\n",
 217                         kproto_version);
 218                 closelog();
 219                 exit(1);
 220         }
 221         ioctl(fdin, AUTOFS_IOC_SETTIMEOUT, &uci_timeout);
 222         timer_add(expire_proc, 15);
 223 }
 224
 225 int autofs_loop(void)
 226 {
 227         chdir("/");
 228         autofs_init();
 229         while(1)
 230         {
 231                 union autofs_v5_packet_union pkt;
 232                 if(autofs_in(&pkt))
 233                 {
 234                         continue;
 235                 }
 236                 log_printf("Got a autofs packet\n");
 237                 if(pkt.hdr.type == autofs_ptype_missing_indirect)
 238                         autofs_process_request(&pkt.missing_indirect);
 239                 else
 240                         log_printf("unknown packet type %d\n", pkt.hdr.type);
 241                 poll(0, 0, 200);
 242         }
 243         umount_autofs();
 244         log_printf("... quitting\n");
 245         closelog();
 246         return 0;
 247 }