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gpg: Reformat parts of decrypt-data.c
* g10/decrypt-data.c (struct decode_filter_context_s): Rename 'defer' to 'holdback' and 'defer_filled' to 'holdbacklen'. Increase size of holdback to allow for future AEAD decryption. Turn 'partial' and 'eof_seen' into bit fields. (decrypt_data): Replace write_status_text by write_Status_printf. Indent parts of the code. -- Signed-off-by: Werner Koch <wk@gnupg.org>
This commit is contained in:
Werner Koch
parent
ddc74f50d4
commit
2f39e00b6b
@ -1,6 +1,7 @@
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/* decrypt-data.c - Decrypt an encrypted data packet
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* Copyright (C) 1998, 1999, 2000, 2001, 2005,
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* 2006, 2009 Free Software Foundation, Inc.
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* Copyright (C) 1998-2001, 2005-2006, 2009 Free Software Foundation, Inc.
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* Copyright (C) 1998-2001, 2005-2006, 2009, 2018 Werner Koch
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* Copyright (C) 2020 g10 Code GmbH
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*
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* This file is part of GnuPG.
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*
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@ -16,6 +17,7 @@
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <https://www.gnu.org/licenses/>.
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* SPDX-License-Identifier: GPL-3.0-or-later
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*/
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#include <config.h>
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@ -37,17 +39,40 @@ static int mdc_decode_filter ( void *opaque, int control, IOBUF a,
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static int decode_filter ( void *opaque, int control, IOBUF a,
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byte *buf, size_t *ret_len);
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typedef struct decode_filter_context_s
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/* Our context object. */
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struct decode_filter_context_s
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{
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gcry_cipher_hd_t cipher_hd;
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gcry_md_hd_t mdc_hash;
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char defer[22];
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int defer_filled;
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int eof_seen;
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/* Recounter (max value is 2). We need it because we do not know
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* whether the iobuf or the outer control code frees this object
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* first. */
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int refcount;
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int partial; /* Working on a partial length packet. */
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size_t length; /* If !partial: Remaining bytes in the packet. */
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} *decode_filter_ctx_t;
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/* The cipher handle. */
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gcry_cipher_hd_t cipher_hd;
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/* The hash handle for use in MDC mode. */
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gcry_md_hd_t mdc_hash;
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/* The holdback buffer and its used length. For AEAD we need 32+1
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* bytes but we use 48 byte. For MDC we need 22 bytes; here
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* holdbacklen will either 0 or 22. */
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char holdback[48];
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unsigned int holdbacklen;
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/* Working on a partial length packet. */
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unsigned int partial : 1;
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/* EOF indicator with these true values:
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* 1 = normal EOF
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* 2 = premature EOF (tag or hash incomplete)
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* 3 = premature EOF (general) */
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unsigned int eof_seen : 2;
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/* Remaining bytes in the packet according to the packet header.
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* Not used if PARTIAL is true. */
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size_t length;
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};
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typedef struct decode_filter_context_s *decode_filter_ctx_t;
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/* Helper to release the decode context. */
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@ -109,12 +134,8 @@ decrypt_data (ctrl_t ctrl, void *procctx, PKT_encrypted *ed, DEK *dek)
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goto leave;
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}
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{
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char buf[20];
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snprintf (buf, sizeof buf, "%d %d", ed->mdc_method, dek->algo);
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write_status_text (STATUS_DECRYPTION_INFO, buf);
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}
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write_status_printf (STATUS_DECRYPTION_INFO, "%d %d %d",
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ed->mdc_method, dek->algo, 0);
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if (opt.show_session_key)
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{
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@ -139,90 +160,93 @@ decrypt_data (ctrl_t ctrl, void *procctx, PKT_encrypted *ed, DEK *dek)
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blocksize = openpgp_cipher_get_algo_blklen (dek->algo);
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if ( !blocksize || blocksize > 16 )
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log_fatal ("unsupported blocksize %u\n", blocksize );
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nprefix = blocksize;
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if ( ed->len && ed->len < (nprefix+2) )
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if (1)
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{
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/* An invalid message. We can't check that during parsing
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because we may not know the used cipher then. */
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rc = gpg_error (GPG_ERR_INV_PACKET);
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goto leave;
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}
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if ( ed->mdc_method )
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{
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if (gcry_md_open (&dfx->mdc_hash, ed->mdc_method, 0 ))
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BUG ();
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if ( DBG_HASHING )
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gcry_md_debug (dfx->mdc_hash, "checkmdc");
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}
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rc = openpgp_cipher_open (&dfx->cipher_hd, dek->algo,
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GCRY_CIPHER_MODE_CFB,
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(GCRY_CIPHER_SECURE
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| ((ed->mdc_method || dek->algo >= 100)?
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0 : GCRY_CIPHER_ENABLE_SYNC)));
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if (rc)
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{
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/* We should never get an error here cause we already checked
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* that the algorithm is available. */
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BUG();
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}
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/* log_hexdump( "thekey", dek->key, dek->keylen );*/
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rc = gcry_cipher_setkey (dfx->cipher_hd, dek->key, dek->keylen);
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if ( gpg_err_code (rc) == GPG_ERR_WEAK_KEY )
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{
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log_info(_("WARNING: message was encrypted with"
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" a weak key in the symmetric cipher.\n"));
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rc=0;
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}
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else if( rc )
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{
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log_error("key setup failed: %s\n", gpg_strerror (rc) );
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goto leave;
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}
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if (!ed->buf)
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{
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log_error(_("problem handling encrypted packet\n"));
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goto leave;
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}
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gcry_cipher_setiv (dfx->cipher_hd, NULL, 0);
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if ( ed->len )
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{
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for (i=0; i < (nprefix+2) && ed->len; i++, ed->len-- )
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nprefix = blocksize;
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if ( ed->len && ed->len < (nprefix+2) )
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{
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if ( (c=iobuf_get(ed->buf)) == -1 )
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break;
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else
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temp[i] = c;
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/* An invalid message. We can't check that during parsing
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* because we may not know the used cipher then. */
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rc = gpg_error (GPG_ERR_INV_PACKET);
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goto leave;
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}
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}
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else
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{
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for (i=0; i < (nprefix+2); i++ )
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if ( (c=iobuf_get(ed->buf)) == -1 )
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break;
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else
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temp[i] = c;
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}
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gcry_cipher_decrypt (dfx->cipher_hd, temp, nprefix+2, NULL, 0);
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gcry_cipher_sync (dfx->cipher_hd);
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p = temp;
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/* log_hexdump( "prefix", temp, nprefix+2 ); */
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if (dek->symmetric
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&& (p[nprefix-2] != p[nprefix] || p[nprefix-1] != p[nprefix+1]) )
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{
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rc = gpg_error (GPG_ERR_BAD_KEY);
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goto leave;
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}
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if ( ed->mdc_method )
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{
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if (gcry_md_open (&dfx->mdc_hash, ed->mdc_method, 0 ))
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BUG ();
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if ( DBG_HASHING )
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gcry_md_debug (dfx->mdc_hash, "checkmdc");
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}
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if ( dfx->mdc_hash )
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gcry_md_write (dfx->mdc_hash, temp, nprefix+2);
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rc = openpgp_cipher_open (&dfx->cipher_hd, dek->algo,
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GCRY_CIPHER_MODE_CFB,
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(GCRY_CIPHER_SECURE
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| ((ed->mdc_method || dek->algo >= 100)?
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0 : GCRY_CIPHER_ENABLE_SYNC)));
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if (rc)
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{
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/* We should never get an error here cause we already checked
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* that the algorithm is available. */
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BUG();
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}
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/* log_hexdump( "thekey", dek->key, dek->keylen );*/
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rc = gcry_cipher_setkey (dfx->cipher_hd, dek->key, dek->keylen);
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if ( gpg_err_code (rc) == GPG_ERR_WEAK_KEY )
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{
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log_info (_("WARNING: message was encrypted with"
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" a weak key in the symmetric cipher.\n"));
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rc = 0;
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}
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else if (rc)
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{
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log_error("key setup failed: %s\n", gpg_strerror (rc) );
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goto leave;
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}
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if (!ed->buf)
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{
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log_error (_("problem handling encrypted packet\n"));
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goto leave;
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}
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gcry_cipher_setiv (dfx->cipher_hd, NULL, 0);
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if ( ed->len )
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{
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for (i=0; i < (nprefix+2) && ed->len; i++, ed->len-- )
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{
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if ( (c=iobuf_get(ed->buf)) == -1 )
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break;
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else
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temp[i] = c;
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}
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}
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else
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{
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for (i=0; i < (nprefix+2); i++ )
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if ( (c=iobuf_get(ed->buf)) == -1 )
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break;
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else
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temp[i] = c;
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}
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gcry_cipher_decrypt (dfx->cipher_hd, temp, nprefix+2, NULL, 0);
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gcry_cipher_sync (dfx->cipher_hd);
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p = temp;
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/* log_hexdump( "prefix", temp, nprefix+2 ); */
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if (dek->symmetric
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&& (p[nprefix-2] != p[nprefix] || p[nprefix-1] != p[nprefix+1]) )
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{
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rc = gpg_error (GPG_ERR_BAD_KEY);
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goto leave;
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}
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if ( dfx->mdc_hash )
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gcry_md_write (dfx->mdc_hash, temp, nprefix+2);
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}
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dfx->refcount++;
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dfx->partial = ed->is_partial;
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@ -287,16 +311,16 @@ decrypt_data (ctrl_t ctrl, void *procctx, PKT_encrypted *ed, DEK *dek)
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log_assert (dfx->cipher_hd);
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log_assert (dfx->mdc_hash);
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gcry_cipher_decrypt (dfx->cipher_hd, dfx->defer, 22, NULL, 0);
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gcry_md_write (dfx->mdc_hash, dfx->defer, 2);
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gcry_cipher_decrypt (dfx->cipher_hd, dfx->holdback, 22, NULL, 0);
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gcry_md_write (dfx->mdc_hash, dfx->holdback, 2);
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gcry_md_final (dfx->mdc_hash);
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if ( dfx->defer[0] != '\xd3'
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|| dfx->defer[1] != '\x14'
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if ( dfx->holdback[0] != '\xd3'
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|| dfx->holdback[1] != '\x14'
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|| datalen != 20
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|| memcmp (gcry_md_read (dfx->mdc_hash, 0), dfx->defer+2, datalen))
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|| memcmp (gcry_md_read (dfx->mdc_hash, 0), dfx->holdback+2, datalen))
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rc = gpg_error (GPG_ERR_BAD_SIGNATURE);
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/* log_printhex("MDC message:", dfx->defer, 22); */
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/* log_printhex("MDC message:", dfx->holdback, 22); */
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/* log_printhex("MDC calc:", gcry_md_read (dfx->mdc_hash,0), datalen); */
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}
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@ -358,14 +382,14 @@ mdc_decode_filter (void *opaque, int control, IOBUF a,
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if (n == 44)
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{
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/* We have enough stuff - flush the deferred stuff. */
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if ( !dfx->defer_filled ) /* First time. */
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if ( !dfx->holdbacklen ) /* First time. */
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{
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memcpy (buf, buf+22, 22);
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n = 22;
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}
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else
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{
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memcpy (buf, dfx->defer, 22);
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memcpy (buf, dfx->holdback, 22);
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}
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/* Fill up the buffer. */
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if (dfx->partial)
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@ -399,10 +423,10 @@ mdc_decode_filter (void *opaque, int control, IOBUF a,
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/* Move the trailing 22 bytes back to the defer buffer. We
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have at least 44 bytes thus a memmove is not needed. */
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n -= 22;
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memcpy (dfx->defer, buf+n, 22 );
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dfx->defer_filled = 1;
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memcpy (dfx->holdback, buf+n, 22 );
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dfx->holdbacklen = 22;
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}
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else if ( !dfx->defer_filled ) /* EOF seen but empty defer buffer. */
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else if ( !dfx->holdbacklen ) /* EOF seen but empty holdback buffer. */
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{
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/* This is bad because it means an incomplete hash. */
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n -= 22;
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@ -411,9 +435,9 @@ mdc_decode_filter (void *opaque, int control, IOBUF a,
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}
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else /* EOF seen (i.e. read less than 22 bytes). */
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{
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memcpy (buf, dfx->defer, 22 );
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memcpy (buf, dfx->holdback, 22 );
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n -= 22;
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memcpy (dfx->defer, buf+n, 22 );
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memcpy (dfx->holdback, buf+n, 22 );
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dfx->eof_seen = 1; /* Normal EOF. */
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}
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