g13: Add commands --suspend and --remove.

* g13/g13.c (aSuspend, aResume): New.
(opts): Add commands --suspend and --resume.
(main): Implement dummy command aUmount.  Implement commands aResume
and aSuspend.
* g13/sh-cmd.c (cmd_suspend): New.
(cmd_resume): New.
(register_commands): Add commands RESUME and SUSPEND.
* g13/server.c (cmd_suspend): New.
(cmd_resume): New.
(register_commands): Add commands RESUME and SUSPEND.
* g13/be-dmcrypt.c (be_dmcrypt_suspend_container): New.
(be_dmcrypt_resume_container): New.
* g13/backend.c (be_suspend_container): New.
(be_resume_container): New.
* g13/suspend.c, g13/suspend.h: New.
* g13/mount.c (parse_header, read_keyblob_prefix, read_keyblob)
(decrypt_keyblob, g13_is_container): Move to ...
* g13/keyblob.c: new file.
(keyblob_read): Rename to g13_keyblob_read and make global.
(keyblob_decrypt): Rename to g13_keyblob_decrypt and make global.
* g13/sh-dmcrypt.c (check_blockdev): Add arg expect_busy.
(sh_dmcrypt_suspend_container): New.
(sh_dmcrypt_resume_container): New.
* g13/call-syshelp.c (call_syshelp_run_suspend): New.
(call_syshelp_run_resume): New.
--

The --suspend command can be used before a hibernate operation to make
the encrypted partition inaccessible and wipe the key from the memory.
Before --suspend is called a sync(1) should be run to make sure that
their are no dirty buffers (dmsetup, as called by g13, actually does
this for you but it does not harm to do it anyway.  After the
partition has been suspended a

  echo 3 >proc/sys/vm/drop_caches

required to flush all caches which may still have content from the
encrypted partition.

The --resume command reverses the effect of the suspend but to do this
it needs to decrypt again.  Now, if the .gnupg directory lives on the
encrypted partition this will be problematic because due to the
suspend all processes accessing data on the encrypted partition will
be put into an uninterruptible sleep (ps(1) shows a state of 'D').
This needs to be avoided.  A workaround is to have a separate GnuPG
home directory (say, "~/.gnupg-fallback") with only the public keys
required to decrypt the partition along with a properly setup
conf files.  A

  GNUPGHOME=$(pwd)/.gnupg-fallback g13 --resume

should then be able to resume the encrypted partition using the
private key stored on a smartcard.

The implementation is pretty basic right now but useful to me.

Signed-off-by: Werner Koch <[email protected]>

1 files changed, 4 insertions, 192 deletions

diff --git a/g13/mount.c b/g13/mount.c
index c5c8f22b4..272cd77e0 100644
--- a/g13/mount.c
+++ b/g13/mount.c
@@ -33,178 +33,10 @@
 #include "keyblob.h"
 #include "backend.h"
 #include "g13tuple.h"
-#include "../common/sysutils.h"
-#include "../common/call-gpg.h"
 #include "mountinfo.h"
 #include "runner.h"
 #include "host2net.h"
-
-
-/* Parse the header prefix and return the length of the entire header.  */
-static gpg_error_t
-parse_header (const char *filename,
-              const unsigned char *packet, size_t packetlen,
-              size_t *r_headerlen)
-{
-  unsigned int len;
-
-  if (packetlen != 32)
-    return gpg_error (GPG_ERR_BUG);
-
-  len = buf32_to_uint (packet+2);
-  if (packet[0] != (0xc0|61) || len < 26
-      || memcmp (packet+6, "GnuPG/G13", 10))
-    {
-      log_error ("file '%s' is not valid container\n", filename);
-      return gpg_error (GPG_ERR_INV_OBJ);
-    }
-  if (packet[16] != 1)
-    {
-      log_error ("unknown version %u of container '%s'\n",
-                 (unsigned int)packet[16], filename);
-      return gpg_error (GPG_ERR_INV_OBJ);
-    }
-  if (packet[17] || packet[18]
-      || packet[26] || packet[27] || packet[28] || packet[29]
-      || packet[30] || packet[31])
-    log_info ("WARNING: unknown meta information in '%s'\n", filename);
-  if (packet[19])
-    log_info ("WARNING: OS flag is not supported in '%s'\n", filename);
-  if (packet[24] > 1 )
-    log_info ("Note: meta data copies in '%s' are ignored\n", filename);
-
-  len = buf32_to_uint (packet+20);
-
-  /* Do a basic sanity check on the length.  */
-  if (len < 32 || len > 1024*1024)
-    {
-      log_error ("bad length given in container '%s'\n", filename);
-      return gpg_error (GPG_ERR_INV_OBJ);
-    }
-
-  *r_headerlen = len;
-  return 0;
-}
-
-
-/* Read the prefix of the keyblob and do some basic parsing.  On
-   success returns an open estream file at R_FP and the length of the
-   header at R_HEADERLEN.  */
-static gpg_error_t
-read_keyblob_prefix (const char *filename, estream_t *r_fp, size_t *r_headerlen)
-{
-  gpg_error_t err;
-  estream_t fp;
-  unsigned char packet[32];
-
-  *r_fp = NULL;
-
-  fp = es_fopen (filename, "rb");
-  if (!fp)
-    {
-      err = gpg_error_from_syserror ();
-      log_error ("error reading '%s': %s\n", filename, gpg_strerror (err));
-      return err;
-    }
-
-  /* Read the header.  It is defined as 32 bytes thus we read it in one go.  */
-  if (es_fread (packet, 32, 1, fp) != 1)
-    {
-      err = gpg_error_from_syserror ();
-      log_error ("error reading the header of '%s': %s\n",
-                 filename, gpg_strerror (err));
-      es_fclose (fp);
-      return err;
-    }
-
-  err = parse_header (filename, packet, 32, r_headerlen);
-  if (err)
-    es_fclose (fp);
-  else
-    *r_fp = fp;
-
-  return err;
-}
-
-
-/* Read the keyblob at FILENAME.  The caller should have acquired a
-   lockfile and checked that the file exists.  */
-static gpg_error_t
-read_keyblob (const char *filename,
-              void **r_enckeyblob, size_t *r_enckeybloblen)
-{
-  gpg_error_t err;
-  estream_t fp = NULL;
-  size_t headerlen = 0;
-  size_t msglen;
-  void *msg = NULL;
-
-  *r_enckeyblob = NULL;
-  *r_enckeybloblen = 0;
-
-  err = read_keyblob_prefix (filename, &fp, &headerlen);
-  if (err)
-    goto leave;
-
-  if (opt.verbose)
-    log_info ("header length of '%s' is %zu\n", filename, headerlen);
-
-  /* Read everything including the padding.  We should eventually do a
-     regular OpenPGP parsing to detect the padding packet and pass
-     only the actual used OpenPGP data to the engine.  This is in
-     particular required when supporting CMS which will be
-     encapsulated in an OpenPGP packet.  */
-  assert (headerlen >= 32);
-  msglen = headerlen - 32;
-  if (!msglen)
-    {
-      err = gpg_error (GPG_ERR_NO_DATA);
-      goto leave;
-    }
-  msg = xtrymalloc (msglen);
-  if (!msglen)
-    {
-      err = gpg_error_from_syserror ();
-      goto leave;
-    }
-  if (es_fread (msg, msglen, 1, fp) != 1)
-    {
-      err = gpg_error_from_syserror ();
-      log_error ("error reading keyblob of '%s': %s\n",
-                 filename, gpg_strerror (err));
-      goto leave;
-    }
-
-  *r_enckeyblob = msg;
-  msg = NULL;
-  *r_enckeybloblen = msglen;
-
- leave:
-  xfree (msg);
-  es_fclose (fp);
-
-  return err;
-}
-
-
-
-
-/* Decrypt the keyblob (ENCKEYBLOB,ENCKEYBLOBLEN) and store the result at
-   (R_KEYBLOB, R_KEYBLOBLEN).  Returns 0 on success or an error code.
-   On error R_KEYBLOB is set to NULL.  */
-static gpg_error_t
-decrypt_keyblob (ctrl_t ctrl, const void *enckeyblob, size_t enckeybloblen,
-                 void **r_keyblob, size_t *r_keybloblen)
-{
-  gpg_error_t err;
-
-  /* FIXME:  For now we only implement OpenPGP.  */
-  err = gpg_decrypt_blob (ctrl, opt.gpg_program, opt.gpg_arguments,
-                          enckeyblob, enckeybloblen,
-                          r_keyblob, r_keybloblen);
-
-  return err;
-}
+#include "../common/sysutils.h"
 
 
 /* Mount the container with name FILENAME at MOUNTPOINT.  */
@@ -285,13 +117,13 @@ g13_mount_container (ctrl_t ctrl, const char *filename, const char *mountpoint)
   /* Read the encrypted keyblob.  */
   /* Fixme: Should we move this to syshelp for dm-crypt or do we
      assume that the encrypted device is world readable?  */
-  err = read_keyblob (filename, &enckeyblob, &enckeybloblen);
+  err = g13_keyblob_read (filename, &enckeyblob, &enckeybloblen);
   if (err)
     goto leave;
 
   /* Decrypt that keyblob and store it in a tuple descriptor.  */
-  err = decrypt_keyblob (ctrl, enckeyblob, enckeybloblen,
-                         &keyblob, &keybloblen);
+  err = g13_keyblob_decrypt (ctrl, enckeyblob, enckeybloblen,
+                             &keyblob, &keybloblen);
   if (err)
     goto leave;
   xfree (enckeyblob);
@@ -386,23 +218,3 @@ g13_umount_container (ctrl_t ctrl, const char *filename, const char *mountpoint)
 
   return 0;
 }
-
-
-/* Test whether the container with name FILENAME is a suitable G13
-   container.  This function may even be called on a mounted
-   container.  */
-gpg_error_t
-g13_is_container (ctrl_t ctrl, const char *filename)
-{
-  gpg_error_t err;
-  estream_t fp = NULL;
-  size_t dummy;
-
-  (void)ctrl;
-
-  /* Read just the prefix of the header.  */
-  err = read_keyblob_prefix (filename, &fp, &dummy);
-  if (!err)
-    es_fclose (fp);
-  return err;
-}