Imported Upstream version 2.0.19upstream/2.0.19

1 files changed, 373 insertions, 0 deletions

diff --git a/g10/encr-data.c b/g10/encr-data.c
new file mode 100644
index 0000000..602ae55
--- /dev/null
+++ b/g10/encr-data.c
@@ -0,0 +1,373 @@
+/* encr-data.c -  process an encrypted data packet
+ * Copyright (C) 1998, 1999, 2000, 2001, 2005,
+ *               2006, 2009, 2012 Free Software Foundation, Inc.
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+#include "gpg.h"
+#include "util.h"
+#include "packet.h"
+#include "cipher.h"
+#include "options.h"
+#include "i18n.h"
+#include "status.h"
+
+
+static int mdc_decode_filter ( void *opaque, int control, IOBUF a,
+                               byte *buf, size_t *ret_len);
+static int decode_filter ( void *opaque, int control, IOBUF a,
+					byte *buf, size_t *ret_len);
+
+typedef struct decode_filter_context_s
+{
+  gcry_cipher_hd_t cipher_hd;
+  gcry_md_hd_t mdc_hash;
+  char defer[22];
+  int  defer_filled;
+  int  eof_seen;
+  int  refcount;
+} *decode_filter_ctx_t;
+
+
+/* Helper to release the decode context.  */
+static void
+release_dfx_context (decode_filter_ctx_t dfx)
+{
+  if (!dfx)
+    return;
+
+  assert (dfx->refcount);
+  if ( !--dfx->refcount )
+    {
+      gcry_cipher_close (dfx->cipher_hd);
+      dfx->cipher_hd = NULL;
+      gcry_md_close (dfx->mdc_hash);
+      dfx->mdc_hash = NULL;
+      xfree (dfx);
+    }
+}
+
+
+
+/****************
+ * Decrypt the data, specified by ED with the key DEK.
+ */
+int
+decrypt_data( void *procctx, PKT_encrypted *ed, DEK *dek )
+{
+  decode_filter_ctx_t dfx;
+  byte *p;
+  int rc=0, c, i;
+  byte temp[32];
+  unsigned blocksize;
+  unsigned nprefix;
+
+  dfx = xtrycalloc (1, sizeof *dfx);
+  if (!dfx)
+    return gpg_error_from_syserror ();
+  dfx->refcount = 1;
+
+  if ( opt.verbose && !dek->algo_info_printed )
+    {
+      if (!openpgp_cipher_test_algo (dek->algo))
+        log_info (_("%s encrypted data\n"),
+                  openpgp_cipher_algo_name (dek->algo));
+      else
+        log_info (_("encrypted with unknown algorithm %d\n"), dek->algo );
+      dek->algo_info_printed = 1;
+    }
+
+  {
+    char buf[20];
+
+    snprintf (buf, sizeof buf, "%d %d", ed->mdc_method, dek->algo);
+    write_status_text (STATUS_DECRYPTION_INFO, buf);
+  }
+
+  rc = openpgp_cipher_test_algo (dek->algo);
+  if (rc)
+    goto leave;
+  blocksize = openpgp_cipher_get_algo_blklen (dek->algo);
+  if ( !blocksize || blocksize > 16 )
+    log_fatal ("unsupported blocksize %u\n", blocksize );
+  nprefix = blocksize;
+  if ( ed->len && ed->len < (nprefix+2) )
+    BUG();
+
+  if ( ed->mdc_method )
+    {
+      if (gcry_md_open (&dfx->mdc_hash, ed->mdc_method, 0 ))
+        BUG ();
+      if ( DBG_HASHING )
+        gcry_md_start_debug (dfx->mdc_hash, "checkmdc");
+    }
+
+  rc = openpgp_cipher_open (&dfx->cipher_hd, dek->algo,
+			    GCRY_CIPHER_MODE_CFB,
+			    (GCRY_CIPHER_SECURE
+			     | ((ed->mdc_method || dek->algo >= 100)?
+				0 : GCRY_CIPHER_ENABLE_SYNC)));
+  if (rc)
+    {
+      /* We should never get an error here cause we already checked
+       * that the algorithm is available.  */
+      BUG();
+    }
+
+
+  /* log_hexdump( "thekey", dek->key, dek->keylen );*/
+  rc = gcry_cipher_setkey (dfx->cipher_hd, dek->key, dek->keylen);
+  if ( gpg_err_code (rc) == GPG_ERR_WEAK_KEY )
+    {
+      log_info(_("WARNING: message was encrypted with"
+                 " a weak key in the symmetric cipher.\n"));
+      rc=0;
+    }
+  else if( rc )
+    {
+      log_error("key setup failed: %s\n", g10_errstr(rc) );
+      goto leave;
+    }
+
+  if (!ed->buf)
+    {
+      log_error(_("problem handling encrypted packet\n"));
+      goto leave;
+    }
+
+  gcry_cipher_setiv (dfx->cipher_hd, NULL, 0);
+
+  if ( ed->len )
+    {
+      for (i=0; i < (nprefix+2) && ed->len; i++, ed->len-- )
+        {
+          if ( (c=iobuf_get(ed->buf)) == -1 )
+            break;
+          else
+            temp[i] = c;
+        }
+    }
+  else
+    {
+      for (i=0; i < (nprefix+2); i++ )
+        if ( (c=iobuf_get(ed->buf)) == -1 )
+          break;
+        else
+          temp[i] = c;
+    }
+
+  gcry_cipher_decrypt (dfx->cipher_hd, temp, nprefix+2, NULL, 0);
+  gcry_cipher_sync (dfx->cipher_hd);
+  p = temp;
+  /* log_hexdump( "prefix", temp, nprefix+2 ); */
+  if (dek->symmetric
+      && (p[nprefix-2] != p[nprefix] || p[nprefix-1] != p[nprefix+1]) )
+    {
+      rc = gpg_error (GPG_ERR_BAD_KEY);
+      goto leave;
+    }
+
+  if ( dfx->mdc_hash )
+    gcry_md_write (dfx->mdc_hash, temp, nprefix+2);
+
+  dfx->refcount++;
+  if ( ed->mdc_method )
+    iobuf_push_filter ( ed->buf, mdc_decode_filter, dfx );
+  else
+    iobuf_push_filter ( ed->buf, decode_filter, dfx );
+
+  proc_packets ( procctx, ed->buf );
+  ed->buf = NULL;
+  if ( ed->mdc_method && dfx->eof_seen == 2 )
+    rc = gpg_error (GPG_ERR_INV_PACKET);
+  else if ( ed->mdc_method )
+    {
+      /* We used to let parse-packet.c handle the MDC packet but this
+         turned out to be a problem with compressed packets: With old
+         style packets there is no length information available and
+         the decompressor uses an implicit end.  However we can't know
+         this implicit end beforehand (:-) and thus may feed the
+         decompressor with more bytes than actually needed.  It would
+         be possible to unread the extra bytes but due to our weird
+         iobuf system any unread is non reliable due to filters
+         already popped off.  The easy and sane solution is to care
+         about the MDC packet only here and never pass it to the
+         packet parser.  Fortunatley the OpenPGP spec requires a
+         strict format for the MDC packet so that we know that 22
+         bytes are appended.  */
+      int datalen = gcry_md_get_algo_dlen (ed->mdc_method);
+
+      assert (dfx->cipher_hd);
+      assert (dfx->mdc_hash);
+      gcry_cipher_decrypt (dfx->cipher_hd, dfx->defer, 22, NULL, 0);
+      gcry_md_write (dfx->mdc_hash, dfx->defer, 2);
+      gcry_md_final (dfx->mdc_hash);
+
+      if (dfx->defer[0] != '\xd3' || dfx->defer[1] != '\x14' )
+        {
+          log_error("mdc_packet with invalid encoding\n");
+          rc = gpg_error (GPG_ERR_INV_PACKET);
+        }
+      else if (datalen != 20
+               || memcmp (gcry_md_read (dfx->mdc_hash, 0),
+                          dfx->defer+2,datalen ))
+        rc = gpg_error (GPG_ERR_BAD_SIGNATURE);
+      /* log_printhex("MDC message:", dfx->defer, 22); */
+      /* log_printhex("MDC calc:", gcry_md_read (dfx->mdc_hash,0), datalen); */
+    }
+
+
+ leave:
+  release_dfx_context (dfx);
+  return rc;
+}
+
+
+
+/* I think we should merge this with cipher_filter */
+static int
+mdc_decode_filter (void *opaque, int control, IOBUF a,
+                   byte *buf, size_t *ret_len)
+{
+  decode_filter_ctx_t dfx = opaque;
+  size_t n, size = *ret_len;
+  int rc = 0;
+  int c;
+
+  if ( control == IOBUFCTRL_UNDERFLOW && dfx->eof_seen )
+    {
+      *ret_len = 0;
+      rc = -1;
+    }
+  else if( control == IOBUFCTRL_UNDERFLOW )
+    {
+      assert (a);
+      assert ( size > 44 );
+
+      /* Get at least 22 bytes and put it somewhere ahead in the buffer. */
+      for (n=22; n < 44 ; n++ )
+        {
+          if( (c = iobuf_get(a)) == -1 )
+            break;
+          buf[n] = c;
+	}
+      if ( n == 44 )
+        {
+          /* We have enough stuff - flush the deferred stuff.  */
+          /* (we asserted that the buffer is large enough) */
+          if ( !dfx->defer_filled )  /* First time. */
+            {
+              memcpy (buf, buf+22, 22 );
+              n = 22;
+	    }
+          else
+            {
+              memcpy (buf, dfx->defer, 22 );
+	    }
+          /* Now fill up. */
+          for (; n < size; n++ )
+            {
+              if ( (c = iobuf_get(a)) == -1 )
+                break;
+              buf[n] = c;
+	    }
+          /* Move the last 22 bytes back to the defer buffer. */
+	  /* (right, we are wasting 22 bytes of the supplied buffer.) */
+          n -= 22;
+          memcpy (dfx->defer, buf+n, 22 );
+          dfx->defer_filled = 1;
+	}
+      else if ( !dfx->defer_filled )  /* EOF seen but empty defer buffer. */
+        {
+          /* This is bad because it means an incomplete hash. */
+          n -= 22;
+          memcpy (buf, buf+22, n );
+          dfx->eof_seen = 2; /* EOF with incomplete hash.  */
+	}
+      else  /* EOF seen (i.e. read less than 22 bytes). */
+        {
+          memcpy (buf, dfx->defer, 22 );
+          n -= 22;
+          memcpy (dfx->defer, buf+n, 22 );
+          dfx->eof_seen = 1; /* Normal EOF. */
+	}
+
+      if ( n )
+        {
+          if ( dfx->cipher_hd )
+            gcry_cipher_decrypt (dfx->cipher_hd, buf, n, NULL, 0);
+          if ( dfx->mdc_hash )
+            gcry_md_write (dfx->mdc_hash, buf, n);
+	}
+      else
+        {
+          assert ( dfx->eof_seen );
+          rc = -1; /* eof */
+	}
+      *ret_len = n;
+    }
+  else if ( control == IOBUFCTRL_FREE )
+    {
+      release_dfx_context (dfx);
+    }
+  else if ( control == IOBUFCTRL_DESC )
+    {
+      *(char**)buf = "mdc_decode_filter";
+    }
+  return rc;
+}
+
+
+static int
+decode_filter( void *opaque, int control, IOBUF a, byte *buf, size_t *ret_len)
+{
+  decode_filter_ctx_t fc = opaque;
+  size_t n, size = *ret_len;
+  int rc = 0;
+
+  if ( control == IOBUFCTRL_UNDERFLOW )
+    {
+      assert(a);
+      n = iobuf_read ( a, buf, size );
+      if ( n == -1 )
+        n = 0;
+      if ( n )
+        {
+          if (fc->cipher_hd)
+            gcry_cipher_decrypt (fc->cipher_hd, buf, n, NULL, 0);
+        }
+      else
+        rc = -1; /* EOF */
+      *ret_len = n;
+    }
+  else if ( control == IOBUFCTRL_FREE )
+    {
+      release_dfx_context (fc);
+    }
+  else if ( control == IOBUFCTRL_DESC )
+    {
+      *(char**)buf = "decode_filter";
+    }
+  return rc;
+}
+