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 static int fdin = 0; /* data coming out of the kernel */
  34 static int fdout = 0;/* data going into the kernel */
  35 static bool term = false;
  36 static dev_t dev;
  37
  38 static time_t uci_timeout;
  39 char uci_path[32];
  40
  41 static void umount_autofs(void)
  42 {
  43         system_printf("umount %s 2> /dev/null", "/tmp/run/mountd/");
  44 }
  45
  46 static int mount_autofs(void)
  47 {
  48         int pipefd[2];
  49         struct stat st;
  50         log_printf("trying to mount %s as the autofs root\n", "/tmp/run/mountd/");
  51         if(is_mounted(0, "/tmp/run/mountd/"))
  52         {
  53                 log_printf("%s is already mounted\n", "/tmp/run/mountd/");
  54                 return -1;
  55         }
  56         fdout = fdin = -1;
  57         mkdir("/tmp/run/mountd/", 0555);
  58         if(pipe(pipefd) < 0)
  59         {
  60                 log_printf("failed to get kernel pipe\n");
  61                 return -1;
  62         }
  63         if(system_printf("/bin/mount -t autofs -o fd=%d,pgrp=%u,minproto=5,maxproto=5 \"mountd(pid%u)\" %s",
  64                 pipefd[1], (unsigned) getpgrp(), getpid(), "/tmp/run/mountd/") != 0)
  65         {
  66                 log_printf("unable to mount autofs on %s\n", "/tmp/run/mountd/");
  67                 close(pipefd[0]);
  68                 close(pipefd[1]);
  69                 return -1;
  70         }
  71
  72         close(pipefd[1]);
  73         fdout = pipefd[0];
  74
  75         fdin = open("/tmp/run/mountd/", O_RDONLY);
  76         if(fdin < 0)
  77         {
  78                 umount_autofs();
  79                 return -1;
  80         }
  81         stat("/tmp/run/mountd/", &st);
  82         return 0;
  83 }
  84
  85 static void send_ready(unsigned int wait_queue_token)
  86 {
  87         if(ioctl(fdin, AUTOFS_IOC_READY, wait_queue_token) < 0)
  88                 log_printf("failed to report ready to kernel\n");
  89 }
  90
  91 static void send_fail(unsigned int wait_queue_token)
  92 {
  93         if(ioctl(fdin, AUTOFS_IOC_FAIL, wait_queue_token) < 0)
  94                 log_printf("failed to report fail to kernel\n");
  95 }
  96
  97 static int autofs_process_request(const struct autofs_v5_packet *pkt)
  98 {
  99         struct stat st;
 100         log_printf("kernel is requesting a mount -> %s\n", pkt->name);
 101         chdir("/tmp/run/mountd/");
 102         if (lstat(pkt->name, &st) == -1 || (S_ISDIR(st.st_mode) && st.st_dev == dev)) {
 103                 if(!mount_new("/tmp/run/mountd/", (char*)pkt->name))
 104                 {
 105                         send_ready(pkt->wait_queue_token);
 106                 } else {
 107                         send_fail(pkt->wait_queue_token);
 108                         log_printf("failed to mount %s\n", pkt->name);
 109                 }
 110         } else {
 111                 send_ready(pkt->wait_queue_token);
 112         }
 113         chdir("/");
 114
 115         return 0;
 116 }
 117
 118 static void expire_proc(void)
 119 {
 120         struct autofs_packet_expire pkt;
 121         while(ioctl(fdin, AUTOFS_IOC_EXPIRE, &pkt) == 0)
 122                 mount_remove("/tmp/run/mountd/", pkt.name);
 123 }
 124
 125 static int fullread(void *ptr, size_t len)
 126 {
 127         char *buf = (char *) ptr;
 128         while(len > 0)
 129         {
 130                 ssize_t r = read(fdout, buf, len);
 131                 if(r == -1)
 132                 {
 133                         if (errno == EINTR)
 134                                 continue;
 135                         break;
 136                 }
 137                 buf += r;
 138                 len -= r;
 139         }
 140         return len;
 141 }
 142
 143 static int autofs_in(union autofs_v5_packet_union *pkt)
 144 {
 145         int res;
 146         struct pollfd fds[1];
 147
 148         fds[0].fd = fdout;
 149         fds[0].events = POLLIN;
 150
 151         while(!term)
 152         {
 153                 res = poll(fds, 1, -1);
 154
 155                 if (res == -1)
 156                 {
 157                         if (errno == EINTR)
 158                                 continue;
 159                         log_printf("failed while trying to read packet from kernel\n");
 160                         return -1;
 161                 }
 162                 else if ((res > 0) && (fds[0].revents & POLLIN))
 163                 {
 164                         return fullread(pkt, sizeof(*pkt));
 165                 }
 166         }
 167         return 1;
 168 }
 169
 170 pid_t autofs_safe_fork(void)
 171 {
 172         pid_t pid = fork();
 173         if(!pid)
 174         {
 175                 close(fdin);
 176                 close(fdout);
 177         }
 178         return pid;
 179 }
 180
 181 static void autofs_cleanup(void)
 182 {
 183         close(fdin);
 184         close(fdout);
 185         umount_autofs();
 186 }
 187
 188 static void autofs_end_handler(int sig)
 189 {
 190         term = true;
 191 }
 192
 193 static void autofs_init(void)
 194 {
 195         int kproto_version;
 196         char *p;
 197         struct uci_context *ctx;
 198         signal_init(autofs_end_handler);
 199         ctx = ucix_init("mountd");
 200         uci_timeout = ucix_get_option_int(ctx, "mountd", "mountd", "timeout", 60);
 201         p = ucix_get_option(ctx, "mountd", "mountd", "path");
 202         ucix_cleanup(ctx);
 203         if(p)
 204                 snprintf(uci_path, 31, "%s", p);
 205         else
 206                 snprintf(uci_path, 31, "/tmp/mounts/");
 207         uci_path[31] = '\0';
 208         mkdir("/tmp/run/", 0555);
 209         mkdir("/tmp/mounts", 0555);
 210         system_printf("rm -rf %s*", uci_path);
 211         if(uci_timeout < 16)
 212                 uci_timeout = 16;
 213         umount_autofs();
 214         mount_init();
 215         if(mount_autofs() < 0)
 216         {
 217                 closelog();
 218                 exit(1);
 219         }
 220         ioctl(fdin, AUTOFS_IOC_PROTOVER, &kproto_version);
 221         if(kproto_version != 5)
 222         {
 223                 log_printf("only kernel protocol version 5 is tested. You have %d.\n",
 224                         kproto_version);
 225                 closelog();
 226                 exit(1);
 227         }
 228         ioctl(fdin, AUTOFS_IOC_SETTIMEOUT, &uci_timeout);
 229         timer_add(expire_proc, 15);
 230 }
 231
 232 int autofs_loop(void)
 233 {
 234         chdir("/");
 235         autofs_init();
 236         while(!term)
 237         {
 238                 union autofs_v5_packet_union pkt;
 239                 if(autofs_in(&pkt))
 240                 {
 241                         continue;
 242                 }
 243                 log_printf("Got a autofs packet\n");
 244                 if(pkt.hdr.type == autofs_ptype_missing_indirect)
 245                         autofs_process_request(&pkt.missing_indirect);
 246                 else
 247                         log_printf("unknown packet type %d\n", pkt.hdr.type);
 248                 poll(0, 0, 200);
 249         }
 250         autofs_cleanup();
 251         log_printf("... quitting\n");
 252         closelog();
 253         return 0;
 254 }