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 <sys/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
  32 int fdin = 0; /* data coming out of the kernel */
  33 int fdout = 0;/* data going into the kernel */
  34 dev_t dev;
  35
  36 time_t uci_timeout;
  37 char uci_path[32];
  38
  39 void umount_autofs(void)
  40 {
  41         system_printf("umount %s 2> /dev/null", "/tmp/run/mountd/");
  42 }
  43
  44 static int mount_autofs(void)
  45 {
  46         int pipefd[2];
  47         struct stat st;
  48         log_printf("trying to mount %s as the autofs root\n", "/tmp/run/mountd/");
  49         if(is_mounted(0, "/tmp/run/mountd/"))
  50         {
  51                 log_printf("%s is already mounted\n", "/tmp/run/mountd/");
  52                 return -1;
  53         }
  54         fdout = fdin = -1;
  55         mkdir("/tmp/run/mountd/", 0555);
  56         if(pipe(pipefd) < 0)
  57         {
  58                 log_printf("failed to get kernel pipe\n");
  59                 return -1;
  60         }
  61         if(system_printf("/bin/mount -t autofs -o fd=%d,pgrp=%u,minproto=5,maxproto=5 \"mountd(pid%u)\" %s",
  62                 pipefd[1], (unsigned) getpgrp(), getpid(), "/tmp/run/mountd/") != 0)
  63         {
  64                 log_printf("unable to mount autofs on %s\n", "/tmp/run/mountd/");
  65                 close(pipefd[0]);
  66                 close(pipefd[1]);
  67                 return -1;
  68         }
  69
  70         close(pipefd[1]);
  71         fdout = pipefd[0];
  72
  73         fdin = open("/tmp/run/mountd/", O_RDONLY);
  74         if(fdin < 0)
  75         {
  76                 umount_autofs();
  77                 return -1;
  78         }
  79         stat("/tmp/run/mountd/", &st);
  80         return 0;
  81 }
  82
  83 static void send_ready(unsigned int wait_queue_token)
  84 {
  85         if(ioctl(fdin, AUTOFS_IOC_READY, wait_queue_token) < 0)
  86                 log_printf("failed to report ready to kernel\n");
  87 }
  88
  89 static void send_fail(unsigned int wait_queue_token)
  90 {
  91         if(ioctl(fdin, AUTOFS_IOC_FAIL, wait_queue_token) < 0)
  92                 log_printf("failed to report fail to kernel\n");
  93 }
  94
  95 static int autofs_process_request(const struct autofs_v5_packet *pkt)
  96 {
  97         struct stat st;
  98         log_printf("kernel is requesting a mount -> %s\n", pkt->name);
  99         chdir("/tmp/run/mountd/");
 100         if (lstat(pkt->name, &st) == -1 || (S_ISDIR(st.st_mode) && st.st_dev == dev)) {
 101                 if(!mount_new("/tmp/run/mountd/", (char*)pkt->name))
 102                 {
 103                         send_ready(pkt->wait_queue_token);
 104                 } else {
 105                         send_fail(pkt->wait_queue_token);
 106                         log_printf("failed to mount %s\n", pkt->name);
 107                 }
 108         } else {
 109                 send_ready(pkt->wait_queue_token);
 110         }
 111         chdir("/");
 112
 113         return 0;
 114 }
 115
 116 void expire_proc(void)
 117 {
 118         struct autofs_packet_expire pkt;
 119         while(ioctl(fdin, AUTOFS_IOC_EXPIRE, &pkt) == 0)
 120                 mount_remove("/tmp/run/mountd/", pkt.name);
 121 }
 122
 123 static int fullread(void *ptr, size_t len)
 124 {
 125         char *buf = (char *) ptr;
 126         while(len > 0)
 127         {
 128                 ssize_t r = read(fdout, buf, len);
 129                 if(r == -1)
 130                 {
 131                         if (errno == EINTR)
 132                                 continue;
 133                         break;
 134                 }
 135                 buf += r;
 136                 len -= r;
 137         }
 138         return len;
 139 }
 140
 141 static int autofs_in(union autofs_v5_packet_union *pkt)
 142 {
 143         struct pollfd fds[1];
 144
 145         fds[0].fd = fdout;
 146         fds[0].events = POLLIN;
 147
 148         while(1)
 149         {
 150                 if(poll(fds, 2, 1000) == -1)
 151                 {
 152                         if (errno == EINTR)
 153                                 continue;
 154                         log_printf("failed while trying to read packet from kernel\n");
 155                         return -1;
 156                 }
 157                 if(fds[0].revents & POLLIN)
 158                         return fullread(pkt, sizeof(*pkt));
 159         }
 160 }
 161
 162 pid_t autofs_safe_fork(void)
 163 {
 164         pid_t pid = fork();
 165         if(!pid)
 166         {
 167                 close(fdin);
 168             close(fdout);
 169         }
 170         return pid;
 171 }
 172
 173 void autofs_cleanup_handler(void)
 174 {
 175         close(fdin);
 176         close(fdout);
 177         umount_autofs();
 178 }
 179
 180 void autofs_init(void)
 181 {
 182         int kproto_version;
 183         char *p;
 184         struct uci_context *ctx;
 185         signal_init(autofs_cleanup_handler);
 186         ctx = ucix_init("mountd");
 187         uci_timeout = ucix_get_option_int(ctx, "mountd", "mountd", "timeout", 60);
 188         p = ucix_get_option(ctx, "mountd", "mountd", "path");
 189         ucix_cleanup(ctx);
 190         if(p)
 191                 snprintf(uci_path, 31, p);
 192         else
 193                 snprintf(uci_path, 31, "/tmp/mounts/");
 194         uci_path[31] = '\0';
 195         mkdir("/tmp/run/", 0555);
 196         mkdir("/tmp/mounts", 0555);
 197         system_printf("rm -rf %s*", uci_path);
 198         if(uci_timeout < 16)
 199                 uci_timeout = 16;
 200         umount_autofs();
 201         mount_init();
 202         if(mount_autofs() < 0)
 203         {
 204                 closelog();
 205                 exit(1);
 206         }
 207         ioctl(fdin, AUTOFS_IOC_PROTOVER, &kproto_version);
 208         if(kproto_version != 5)
 209         {
 210                 log_printf("only kernel protocol version 5 is tested. You have %d.\n",
 211                         kproto_version);
 212                 closelog();
 213                 exit(1);
 214         }
 215         ioctl(fdin, AUTOFS_IOC_SETTIMEOUT, &uci_timeout);
 216         timer_add(expire_proc, 15);
 217 }
 218
 219 int autofs_loop(void)
 220 {
 221         chdir("/");
 222         autofs_init();
 223         while(1)
 224         {
 225                 union autofs_v5_packet_union pkt;
 226                 if(autofs_in(&pkt))
 227                 {
 228                         continue;
 229                 }
 230                 log_printf("Got a autofs packet\n");
 231                 if(pkt.hdr.type == autofs_ptype_missing_indirect)
 232                         autofs_process_request(&pkt.missing_indirect);
 233                 else
 234                         log_printf("unknown packet type %d\n", pkt.hdr.type);
 235                 poll(0, 0, 200);
 236         }
 237         umount_autofs();
 238         log_printf("... quitting\n");
 239         closelog();
 240         return 0;
 241 }