blog/Broken_umask_handling_with_sshfs.html

   1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
   2           "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
   3 <html xmlns="http://www.w3.org/1999/xhtml" dir="ltr">
   4   <head>
   5     <meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
   6     <title>Petter Reinholdtsen: Broken umask handling with sshfs</title>
   7     <link rel="stylesheet" type="text/css" media="screen" href="http://people.skolelinux.org/pere/blog/style.css" />
   8     <link rel="stylesheet" type="text/css" media="screen" href="http://people.skolelinux.org/pere/blog/vim.css" />
   9   </head>
  10   <body>
  11     <div class="title">
  12  <h1>
  13      <a href="http://people.skolelinux.org/pere/blog/">Petter Reinholdtsen</a>
  14
  15  </h1>
  16
  17 </div>
  18
  19
  20     <div class="entry">
  21       <div class="title">Broken umask handling with sshfs</div>
  22       <div class="date">26th August 2010</div>
  23       <div class="body"><p>My file system sematics program
  24 <a href="http://people.skolelinux.org/pere/blog/Testing_if_a_file_system_can_be_used_for_home_directories___.html">presented
  25 a few days ago</a> is very useful to verify that a file system can
  26 work as a unix home directory,and today I had to extend it a bit.  I'm
  27 looking into alternatives for home directory access here at the
  28 University of Oslo, and one of the options is sshfs.  My friend
  29 Finn-Arne mentioned a while back that they had used sshfs with Debian
  30 Edu, but stopped because of problems.  I asked today what the problems
  31 where, and he mentioned that sshfs failed to handle umask properly.
  32 Trying to detect the problem I wrote this addition to my fs testing
  33 script:</p>
  34
  35 <pre>
  36 mode_t touch_get_mode(const char *name, mode_t mode) {
  37   mode_t retval = 0;
  38   int fd = open(name, O_RDWR|O_CREAT|O_LARGEFILE, mode);
  39   if (-1 != fd) {
  40     unlink(name);
  41     struct stat statbuf;
  42     if (-1 != fstat(fd, &statbuf)) {
  43       retval = statbuf.st_mode & 0x1ff;
  44     }
  45     close(fd);
  46   }
  47   return retval;
  48 }
  49
  50 /* Try to detect problem discovered using sshfs */
  51 int test_umask(void) {
  52   printf("info: testing umask effect on file creation\n");
  53
  54   mode_t orig_umask = umask(000);
  55   mode_t newmode;
  56   if (0666 != (newmode = touch_get_mode("foobar", 0666))) {
  57     printf("  error: Wrong file mode %o when creating using mode 666 and umask 000\n",
  58            newmode);
  59   }
  60   umask(007);
  61   if (0660 != (newmode = touch_get_mode("foobar", 0666))) {
  62     printf("  error: Wrong file mode %o when creating using mode 666 and umask 007\n",
  63            newmode);
  64   }
  65
  66   umask (orig_umask);
  67   return 0;
  68 }
  69
  70 int main(int argc, char **argv) {
  71   [...]
  72   test_umask();
  73   return 0;
  74 }
  75 </pre>
  76
  77 <p>Sure enough.  On NFS to a netapp, I get this result:</p>
  78
  79 <pre>
  80 Testing POSIX/Unix sematics on file system
  81 info: testing symlink creation
  82 info: testing subdirectory creation
  83 info: testing fcntl locking
  84   Read-locking 1 byte from 1073741824
  85   Read-locking 510 byte from 1073741826
  86   Unlocking 1 byte from 1073741824
  87   Write-locking 1 byte from 1073741824
  88   Write-locking 510 byte from 1073741826
  89   Unlocking 2 byte from 1073741824
  90 info: testing umask effect on file creation
  91 </pre>
  92
  93 <p>When mounting the same directory using sshfs, I get this
  94 result:</p>
  95
  96 <pre>
  97 Testing POSIX/Unix sematics on file system
  98 info: testing symlink creation
  99 info: testing subdirectory creation
 100 info: testing fcntl locking
 101   Read-locking 1 byte from 1073741824
 102   Read-locking 510 byte from 1073741826
 103   Unlocking 1 byte from 1073741824
 104   Write-locking 1 byte from 1073741824
 105   Write-locking 510 byte from 1073741826
 106   Unlocking 2 byte from 1073741824
 107 info: testing umask effect on file creation
 108   error: Wrong file mode 644 when creating using mode 666 and umask 000
 109   error: Wrong file mode 640 when creating using mode 666 and umask 007
 110 </pre>
 111
 112 <p>So, I can conclude that sshfs is better than smb to a Netapp or a
 113 Windows server, but not good enough to be used as a home
 114 directory.</p>
 115
 116 <p>Update 2010-08-26: Reported the issue in
 117 <a href="http://bugs.debian.org/594498">BTS report #594498</a></p>
 118
 119 <p>Update 2010-08-27: Michael Gebetsroither report that he found the
 120 script so useful that he created a GIT repository and stored it in
 121 <a href="http://github.com/gebi/fs-test">http://github.com/gebi/fs-test</a>.</p>
 122 </div>
 123
 124       <div class="tags">Tags: <a href="http://people.skolelinux.org/pere/blog/tags/debian edu">debian edu</a>, <a href="http://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="http://people.skolelinux.org/pere/blog/tags/nuug">nuug</a>.</div>
 125
 126
 127     </div>
 128
 129
 130
 131
 132     <div id="sidebar">
 133
 134
 135
 136 <h2>Archive</h2>
 137 <ul>
 138
 139 <li>2013
 140 <ul>
 141
 142 <li><a href="http://people.skolelinux.org/pere/blog/archive/2013/01/">January (3)</a></li>
 143
 144 </ul></li>
 145
 146 <li>2012
 147 <ul>
 148
 149 <li><a href="http://people.skolelinux.org/pere/blog/archive/2012/01/">January (7)</a></li>
 150
 151 <li><a href="http://people.skolelinux.org/pere/blog/archive/2012/02/">February (10)</a></li>
 152
 153 <li><a href="http://people.skolelinux.org/pere/blog/archive/2012/03/">March (17)</a></li>
 154
 155 <li><a href="http://people.skolelinux.org/pere/blog/archive/2012/04/">April (12)</a></li>
 156
 157 <li><a href="http://people.skolelinux.org/pere/blog/archive/2012/05/">May (12)</a></li>
 158
 159 <li><a href="http://people.skolelinux.org/pere/blog/archive/2012/06/">June (20)</a></li>
 160
 161 <li><a href="http://people.skolelinux.org/pere/blog/archive/2012/07/">July (17)</a></li>
 162
 163 <li><a href="http://people.skolelinux.org/pere/blog/archive/2012/08/">August (6)</a></li>
 164
 165 <li><a href="http://people.skolelinux.org/pere/blog/archive/2012/09/">September (9)</a></li>
 166
 167 <li><a href="http://people.skolelinux.org/pere/blog/archive/2012/10/">October (17)</a></li>
 168
 169 <li><a href="http://people.skolelinux.org/pere/blog/archive/2012/11/">November (10)</a></li>
 170
 171 <li><a href="http://people.skolelinux.org/pere/blog/archive/2012/12/">December (7)</a></li>
 172
 173 </ul></li>
 174
 175 <li>2011
 176 <ul>
 177
 178 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/01/">January (16)</a></li>
 179
 180 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/02/">February (6)</a></li>
 181
 182 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/03/">March (6)</a></li>
 183
 184 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/04/">April (7)</a></li>
 185
 186 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/05/">May (3)</a></li>
 187
 188 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/06/">June (2)</a></li>
 189
 190 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/07/">July (7)</a></li>
 191
 192 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/08/">August (6)</a></li>
 193
 194 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/09/">September (4)</a></li>
 195
 196 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/10/">October (2)</a></li>
 197
 198 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/11/">November (3)</a></li>
 199
 200 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/12/">December (1)</a></li>
 201
 202 </ul></li>
 203
 204 <li>2010
 205 <ul>
 206
 207 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/01/">January (2)</a></li>
 208
 209 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/02/">February (1)</a></li>
 210
 211 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/03/">March (3)</a></li>
 212
 213 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/04/">April (3)</a></li>
 214
 215 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/05/">May (9)</a></li>
 216
 217 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/06/">June (14)</a></li>
 218
 219 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/07/">July (12)</a></li>
 220
 221 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/08/">August (13)</a></li>
 222
 223 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/09/">September (7)</a></li>
 224
 225 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/10/">October (9)</a></li>
 226
 227 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/11/">November (13)</a></li>
 228
 229 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/12/">December (12)</a></li>
 230
 231 </ul></li>
 232
 233 <li>2009
 234 <ul>
 235
 236 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/01/">January (8)</a></li>
 237
 238 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/02/">February (8)</a></li>
 239
 240 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/03/">March (12)</a></li>
 241
 242 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/04/">April (10)</a></li>
 243
 244 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/05/">May (9)</a></li>
 245
 246 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/06/">June (3)</a></li>
 247
 248 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/07/">July (4)</a></li>
 249
 250 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/08/">August (3)</a></li>
 251
 252 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/09/">September (1)</a></li>
 253
 254 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/10/">October (2)</a></li>
 255
 256 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/11/">November (3)</a></li>
 257
 258 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/12/">December (3)</a></li>
 259
 260 </ul></li>
 261
 262 <li>2008
 263 <ul>
 264
 265 <li><a href="http://people.skolelinux.org/pere/blog/archive/2008/11/">November (5)</a></li>
 266
 267 <li><a href="http://people.skolelinux.org/pere/blog/archive/2008/12/">December (7)</a></li>
 268
 269 </ul></li>
 270
 271 </ul>
 272
 273
 274
 275 <h2>Tags</h2>
 276 <ul>
 277
 278  <li><a href="http://people.skolelinux.org/pere/blog/tags/3d-printer">3d-printer (13)</a></li>
 279
 280  <li><a href="http://people.skolelinux.org/pere/blog/tags/amiga">amiga (1)</a></li>
 281
 282  <li><a href="http://people.skolelinux.org/pere/blog/tags/aros">aros (1)</a></li>
 283
 284  <li><a href="http://people.skolelinux.org/pere/blog/tags/bankid">bankid (4)</a></li>
 285
 286  <li><a href="http://people.skolelinux.org/pere/blog/tags/bitcoin">bitcoin (5)</a></li>
 287
 288  <li><a href="http://people.skolelinux.org/pere/blog/tags/bootsystem">bootsystem (12)</a></li>
 289
 290  <li><a href="http://people.skolelinux.org/pere/blog/tags/bsa">bsa (2)</a></li>
 291
 292  <li><a href="http://people.skolelinux.org/pere/blog/tags/debian">debian (61)</a></li>
 293
 294  <li><a href="http://people.skolelinux.org/pere/blog/tags/debian edu">debian edu (118)</a></li>
 295
 296  <li><a href="http://people.skolelinux.org/pere/blog/tags/digistan">digistan (9)</a></li>
 297
 298  <li><a href="http://people.skolelinux.org/pere/blog/tags/docbook">docbook (7)</a></li>
 299
 300  <li><a href="http://people.skolelinux.org/pere/blog/tags/drivstoffpriser">drivstoffpriser (4)</a></li>
 301
 302  <li><a href="http://people.skolelinux.org/pere/blog/tags/english">english (167)</a></li>
 303
 304  <li><a href="http://people.skolelinux.org/pere/blog/tags/fiksgatami">fiksgatami (21)</a></li>
 305
 306  <li><a href="http://people.skolelinux.org/pere/blog/tags/fildeling">fildeling (12)</a></li>
 307
 308  <li><a href="http://people.skolelinux.org/pere/blog/tags/freeculture">freeculture (10)</a></li>
 309
 310  <li><a href="http://people.skolelinux.org/pere/blog/tags/frikanalen">frikanalen (9)</a></li>
 311
 312  <li><a href="http://people.skolelinux.org/pere/blog/tags/intervju">intervju (32)</a></li>
 313
 314  <li><a href="http://people.skolelinux.org/pere/blog/tags/kart">kart (17)</a></li>
 315
 316  <li><a href="http://people.skolelinux.org/pere/blog/tags/ldap">ldap (8)</a></li>
 317
 318  <li><a href="http://people.skolelinux.org/pere/blog/tags/lenker">lenker (6)</a></li>
 319
 320  <li><a href="http://people.skolelinux.org/pere/blog/tags/ltsp">ltsp (1)</a></li>
 321
 322  <li><a href="http://people.skolelinux.org/pere/blog/tags/multimedia">multimedia (25)</a></li>
 323
 324  <li><a href="http://people.skolelinux.org/pere/blog/tags/norsk">norsk (219)</a></li>
 325
 326  <li><a href="http://people.skolelinux.org/pere/blog/tags/nuug">nuug (148)</a></li>
 327
 328  <li><a href="http://people.skolelinux.org/pere/blog/tags/offentlig innsyn">offentlig innsyn (6)</a></li>
 329
 330  <li><a href="http://people.skolelinux.org/pere/blog/tags/open311">open311 (2)</a></li>
 331
 332  <li><a href="http://people.skolelinux.org/pere/blog/tags/opphavsrett">opphavsrett (41)</a></li>
 333
 334  <li><a href="http://people.skolelinux.org/pere/blog/tags/personvern">personvern (61)</a></li>
 335
 336  <li><a href="http://people.skolelinux.org/pere/blog/tags/raid">raid (1)</a></li>
 337
 338  <li><a href="http://people.skolelinux.org/pere/blog/tags/reprap">reprap (11)</a></li>
 339
 340  <li><a href="http://people.skolelinux.org/pere/blog/tags/rfid">rfid (2)</a></li>
 341
 342  <li><a href="http://people.skolelinux.org/pere/blog/tags/robot">robot (5)</a></li>
 343
 344  <li><a href="http://people.skolelinux.org/pere/blog/tags/rss">rss (1)</a></li>
 345
 346  <li><a href="http://people.skolelinux.org/pere/blog/tags/ruter">ruter (4)</a></li>
 347
 348  <li><a href="http://people.skolelinux.org/pere/blog/tags/scraperwiki">scraperwiki (2)</a></li>
 349
 350  <li><a href="http://people.skolelinux.org/pere/blog/tags/sikkerhet">sikkerhet (28)</a></li>
 351
 352  <li><a href="http://people.skolelinux.org/pere/blog/tags/sitesummary">sitesummary (4)</a></li>
 353
 354  <li><a href="http://people.skolelinux.org/pere/blog/tags/skepsis">skepsis (4)</a></li>
 355
 356  <li><a href="http://people.skolelinux.org/pere/blog/tags/standard">standard (39)</a></li>
 357
 358  <li><a href="http://people.skolelinux.org/pere/blog/tags/stavekontroll">stavekontroll (3)</a></li>
 359
 360  <li><a href="http://people.skolelinux.org/pere/blog/tags/stortinget">stortinget (5)</a></li>
 361
 362  <li><a href="http://people.skolelinux.org/pere/blog/tags/surveillance">surveillance (12)</a></li>
 363
 364  <li><a href="http://people.skolelinux.org/pere/blog/tags/sysadmin">sysadmin (1)</a></li>
 365
 366  <li><a href="http://people.skolelinux.org/pere/blog/tags/valg">valg (7)</a></li>
 367
 368  <li><a href="http://people.skolelinux.org/pere/blog/tags/video">video (35)</a></li>
 369
 370  <li><a href="http://people.skolelinux.org/pere/blog/tags/vitenskap">vitenskap (4)</a></li>
 371
 372  <li><a href="http://people.skolelinux.org/pere/blog/tags/web">web (26)</a></li>
 373
 374 </ul>
 375
 376
 377     </div>
 378     <p style="text-align: right">
 379  Created by <a href="http://steve.org.uk/Software/chronicle">Chronicle v4.4</a>
 380 </p>
 381
 382   </body>
 383 </html>