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-rw-r--r--sm/decrypt.c1166
1 files changed, 1166 insertions, 0 deletions
diff --git a/sm/decrypt.c b/sm/decrypt.c
new file mode 100644
index 0000000..2aa716f
--- /dev/null
+++ b/sm/decrypt.c
@@ -0,0 +1,1166 @@
+/* decrypt.c - Decrypt a message
+ * Copyright (C) 2001, 2003, 2010 Free Software Foundation, Inc.
+ * Copyright (C) 2001-2019 Werner Koch
+ * Copyright (C) 2015-2021 g10 Code GmbH
+ *
+ * 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 <https://www.gnu.org/licenses/>.
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <time.h>
+#include <assert.h>
+
+#include "gpgsm.h"
+#include <gcrypt.h>
+#include <ksba.h>
+
+#include "keydb.h"
+#include "../common/i18n.h"
+#include "../common/compliance.h"
+#include "../common/tlv.h"
+
+/* We can provide an enum value which is only availabale with KSBA
+ * 1.6.0 so that we can compile even against older versions. Some
+ * calls will of course return an error in this case. This value is
+ * currently not used because the cipher mode is sufficient here. */
+/* #if KSBA_VERSION_NUMBER < 0x010600 /\* 1.6.0 *\/ */
+/* # define KSBA_CT_AUTHENVELOPED_DATA 10 */
+/* #endif */
+
+
+struct decrypt_filter_parm_s
+{
+ int algo;
+ int mode;
+ int blklen;
+ gcry_cipher_hd_t hd;
+ char iv[16];
+ size_t ivlen;
+ int any_data; /* did we push anything through the filter at all? */
+ unsigned char lastblock[16]; /* to strip the padding we have to
+ keep this one */
+ char helpblock[16]; /* needed because there is no block buffering in
+ libgcrypt (yet) */
+ int helpblocklen;
+ int is_de_vs; /* Helper to track CO_DE_VS state. */
+};
+
+
+/* Return the hash algorithm's algo id from its name given in the
+ * non-null termnated string in (buffer,buflen). Returns 0 on failure
+ * or if the algo is not known. */
+static char *
+string_from_gcry_buffer (gcry_buffer_t *buffer)
+{
+ char *string;
+
+ string = xtrymalloc (buffer->len + 1);
+ if (!string)
+ return NULL;
+ memcpy (string, buffer->data, buffer->len);
+ string[buffer->len] = 0;
+ return string;
+}
+
+
+/* Helper for pwri_decrypt to parse the derive info.
+ * Example data for (DER,DERLEN):
+ * SEQUENCE {
+ * OCTET STRING
+ * 60 76 4B E9 5E DF 3C F8 B2 F9 B6 C2 7D 5A FB 90
+ * 23 B6 47 DF
+ * INTEGER 10000
+ * SEQUENCE {
+ * OBJECT IDENTIFIER
+ * hmacWithSHA512 (1 2 840 113549 2 11)
+ * NULL
+ * }
+ * }
+ */
+static gpg_error_t
+pwri_parse_pbkdf2 (const unsigned char *der, size_t derlen,
+ unsigned char const **r_salt, unsigned int *r_saltlen,
+ unsigned long *r_iterations,
+ enum gcry_md_algos *r_digest)
+{
+ gpg_error_t err;
+ size_t objlen, hdrlen;
+ int class, tag, constructed, ndef;
+ char *oidstr;
+
+ err = parse_ber_header (&der, &derlen, &class, &tag, &constructed,
+ &ndef, &objlen, &hdrlen);
+ if (!err && (objlen > derlen || tag != TAG_SEQUENCE
+ || !constructed || ndef))
+ err = gpg_error (GPG_ERR_INV_OBJ);
+ if (err)
+ return err;
+ derlen = objlen;
+
+ err = parse_ber_header (&der, &derlen, &class, &tag, &constructed,
+ &ndef, &objlen, &hdrlen);
+ if (!err && (objlen > derlen || tag != TAG_OCTET_STRING
+ || constructed || ndef))
+ err = gpg_error (GPG_ERR_INV_OBJ);
+ if (err)
+ return err;
+ *r_salt = der;
+ *r_saltlen = objlen;
+ der += objlen;
+ derlen -= objlen;
+
+ err = parse_ber_header (&der, &derlen, &class, &tag, &constructed,
+ &ndef, &objlen, &hdrlen);
+ if (!err && (objlen > derlen || tag != TAG_INTEGER
+ || constructed || ndef))
+ err = gpg_error (GPG_ERR_INV_OBJ);
+ if (err)
+ return err;
+ *r_iterations = 0;
+ for (; objlen; objlen--)
+ {
+ *r_iterations <<= 8;
+ *r_iterations |= (*der++) & 0xff;
+ derlen--;
+ }
+
+ err = parse_ber_header (&der, &derlen, &class, &tag, &constructed,
+ &ndef, &objlen, &hdrlen);
+ if (!err && (objlen > derlen || tag != TAG_SEQUENCE
+ || !constructed || ndef))
+ err = gpg_error (GPG_ERR_INV_OBJ);
+ if (err)
+ return err;
+ derlen = objlen;
+
+ err = parse_ber_header (&der, &derlen, &class, &tag, &constructed,
+ &ndef, &objlen, &hdrlen);
+ if (!err && (objlen > derlen || tag != TAG_OBJECT_ID
+ || constructed || ndef))
+ err = gpg_error (GPG_ERR_INV_OBJ);
+ if (err)
+ return err;
+
+ oidstr = ksba_oid_to_str (der, objlen);
+ if (!oidstr)
+ return gpg_error_from_syserror ();
+ *r_digest = gcry_md_map_name (oidstr);
+ if (*r_digest)
+ ;
+ else if (!strcmp (oidstr, "1.2.840.113549.2.7"))
+ *r_digest = GCRY_MD_SHA1;
+ else if (!strcmp (oidstr, "1.2.840.113549.2.8"))
+ *r_digest = GCRY_MD_SHA224;
+ else if (!strcmp (oidstr, "1.2.840.113549.2.9"))
+ *r_digest = GCRY_MD_SHA256;
+ else if (!strcmp (oidstr, "1.2.840.113549.2.10"))
+ *r_digest = GCRY_MD_SHA384;
+ else if (!strcmp (oidstr, "1.2.840.113549.2.11"))
+ *r_digest = GCRY_MD_SHA512;
+ else
+ err = gpg_error (GPG_ERR_DIGEST_ALGO);
+ ksba_free (oidstr);
+
+ return err;
+}
+
+
+/* Password based decryption.
+ * ENC_VAL has the form:
+ * (enc-val
+ * (pwri
+ * (derive-algo <oid>) --| both are optional
+ * (derive-parm <der>) --|
+ * (encr-algo <oid>)
+ * (encr-parm <iv>)
+ * (encr-key <key>))) -- this is the encrypted session key
+ *
+ */
+static gpg_error_t
+pwri_decrypt (ctrl_t ctrl, gcry_sexp_t enc_val,
+ unsigned char **r_result, unsigned int *r_resultlen,
+ struct decrypt_filter_parm_s *parm)
+{
+ gpg_error_t err;
+ gcry_buffer_t ioarray[5] = { {0} };
+ char *derive_algo_str = NULL;
+ char *encr_algo_str = NULL;
+ const unsigned char *dparm; /* Alias for ioarray[1]. */
+ unsigned int dparmlen;
+ const unsigned char *eparm; /* Alias for ioarray[3]. */
+ unsigned int eparmlen;
+ const unsigned char *ekey; /* Alias for ioarray[4]. */
+ unsigned int ekeylen;
+ unsigned char kek[32];
+ unsigned int keklen;
+ enum gcry_cipher_algos encr_algo;
+ enum gcry_cipher_modes encr_mode;
+ gcry_cipher_hd_t encr_hd = NULL;
+ unsigned char *result = NULL;
+ unsigned int resultlen;
+ unsigned int blklen;
+ const unsigned char *salt; /* Points int dparm. */
+ unsigned int saltlen;
+ unsigned long iterations;
+ enum gcry_md_algos digest_algo;
+ char *passphrase = NULL;
+
+
+ *r_resultlen = 0;
+ *r_result = NULL;
+
+ err = gcry_sexp_extract_param (enc_val, "enc-val!pwri",
+ "&'derive-algo'?'derive-parm'?"
+ "'encr-algo''encr-parm''encr-key'",
+ ioarray+0, ioarray+1,
+ ioarray+2, ioarray+3, ioarray+4, NULL);
+ if (err)
+ {
+ /* If this is not pwri element, it is likly a kekri element
+ * which we do not yet support. Change the error back to the
+ * original as returned by ksba_cms_get_issuer. */
+ if (gpg_err_code (err) == GPG_ERR_NOT_FOUND)
+ err = gpg_error (GPG_ERR_UNSUPPORTED_CMS_OBJ);
+ else
+ log_error ("extracting PWRI parameter failed: %s\n",
+ gpg_strerror (err));
+ goto leave;
+ }
+
+ if (ioarray[0].data)
+ {
+ derive_algo_str = string_from_gcry_buffer (ioarray+0);
+ if (!derive_algo_str)
+ {
+ err = gpg_error_from_syserror ();
+ goto leave;
+ }
+ }
+ dparm = ioarray[1].data;
+ dparmlen = ioarray[1].len;
+ encr_algo_str = string_from_gcry_buffer (ioarray+2);
+ if (!encr_algo_str)
+ {
+ err = gpg_error_from_syserror ();
+ goto leave;
+ }
+ eparm = ioarray[3].data;
+ eparmlen = ioarray[3].len;
+ ekey = ioarray[4].data;
+ ekeylen = ioarray[4].len;
+
+ /* Check parameters. */
+ if (DBG_CRYPTO)
+ {
+ if (derive_algo_str)
+ {
+ log_debug ("derive algo: %s\n", derive_algo_str);
+ log_printhex (dparm, dparmlen, "derive parm:");
+ }
+ log_debug ("encr algo .: %s\n", encr_algo_str);
+ log_printhex (eparm, eparmlen, "encr parm .:");
+ log_printhex (ekey, ekeylen, "encr key .:");
+ }
+
+ if (!derive_algo_str)
+ {
+ err = gpg_error (GPG_ERR_NOT_SUPPORTED);
+ log_info ("PWRI with no key derivation detected\n");
+ goto leave;
+ }
+ if (strcmp (derive_algo_str, "1.2.840.113549.1.5.12"))
+ {
+ err = gpg_error (GPG_ERR_NOT_SUPPORTED);
+ log_info ("PWRI does not use PBKDF2 (but %s)\n", derive_algo_str);
+ goto leave;
+ }
+
+ digest_algo = 0; /*(silence cc warning)*/
+ err = pwri_parse_pbkdf2 (dparm, dparmlen,
+ &salt, &saltlen, &iterations, &digest_algo);
+ if (err)
+ {
+ log_error ("parsing PWRI parameter failed: %s\n", gpg_strerror (err));
+ goto leave;
+ }
+
+ parm->is_de_vs = (parm->is_de_vs
+ && gnupg_digest_is_compliant (CO_DE_VS, digest_algo));
+
+
+ encr_algo = gcry_cipher_map_name (encr_algo_str);
+ encr_mode = gcry_cipher_mode_from_oid (encr_algo_str);
+ if (!encr_algo || !encr_mode)
+ {
+ log_error ("PWRI uses unknown algorithm %s\n", encr_algo_str);
+ err = gpg_error (GPG_ERR_CIPHER_ALGO);
+ goto leave;
+ }
+
+ parm->is_de_vs =
+ (parm->is_de_vs
+ && gnupg_cipher_is_compliant (CO_DE_VS, encr_algo, encr_mode));
+
+ keklen = gcry_cipher_get_algo_keylen (encr_algo);
+ blklen = gcry_cipher_get_algo_blklen (encr_algo);
+ if (!keklen || keklen > sizeof kek || blklen != 16 )
+ {
+ log_error ("PWRI algorithm %s cannot be used\n", encr_algo_str);
+ err = gpg_error (GPG_ERR_INV_KEYLEN);
+ goto leave;
+ }
+ if ((ekeylen % blklen) || (ekeylen / blklen < 2))
+ {
+ /* Note that we need at least two full blocks. */
+ log_error ("PWRI uses a wrong length of encrypted key\n");
+ err = gpg_error (GPG_ERR_INV_KEYLEN);
+ goto leave;
+ }
+
+ err = gpgsm_agent_ask_passphrase
+ (ctrl,
+ i18n_utf8 (N_("Please enter the passphrase for decryption.")),
+ 0, &passphrase);
+ if (err)
+ goto leave;
+
+ err = gcry_kdf_derive (passphrase, strlen (passphrase),
+ GCRY_KDF_PBKDF2, digest_algo,
+ salt, saltlen, iterations,
+ keklen, kek);
+ if (passphrase)
+ {
+ wipememory (passphrase, strlen (passphrase));
+ xfree (passphrase);
+ passphrase = NULL;
+ }
+ if (err)
+ {
+ log_error ("deriving key from passphrase failed: %s\n",
+ gpg_strerror (err));
+ goto leave;
+ }
+
+ if (DBG_CRYPTO)
+ log_printhex (kek, keklen, "KEK .......:");
+
+ /* Unwrap the key. */
+ resultlen = ekeylen;
+ result = xtrymalloc_secure (resultlen);
+ if (!result)
+ {
+ err = gpg_error_from_syserror ();
+ goto leave;
+ }
+
+ err = gcry_cipher_open (&encr_hd, encr_algo, encr_mode, 0);
+ if (err)
+ {
+ log_error ("PWRI failed to open cipher: %s\n", gpg_strerror (err));
+ goto leave;
+ }
+
+ err = gcry_cipher_setkey (encr_hd, kek, keklen);
+ wipememory (kek, sizeof kek);
+ if (!err)
+ err = gcry_cipher_setiv (encr_hd, ekey + ekeylen - 2 * blklen, blklen);
+ if (!err)
+ err = gcry_cipher_decrypt (encr_hd, result + ekeylen - blklen, blklen,
+ ekey + ekeylen - blklen, blklen);
+ if (!err)
+ err = gcry_cipher_setiv (encr_hd, result + ekeylen - blklen, blklen);
+ if (!err)
+ err = gcry_cipher_decrypt (encr_hd, result, ekeylen - blklen,
+ ekey, ekeylen - blklen);
+ /* (We assume that that eparm is the octet string with the IV) */
+ if (!err)
+ err = gcry_cipher_setiv (encr_hd, eparm, eparmlen);
+ if (!err)
+ err = gcry_cipher_decrypt (encr_hd, result, resultlen, NULL, 0);
+
+ if (err)
+ {
+ log_error ("KEK decryption failed for PWRI: %s\n", gpg_strerror (err));
+ goto leave;
+ }
+
+ if (DBG_CRYPTO)
+ log_printhex (result, resultlen, "Frame .....:");
+
+ if (result[0] < 8 /* At least 64 bits */
+ || (result[0] % 8) /* Multiple of 64 bits */
+ || result[0] > resultlen - 4 /* Not more than the size of the input */
+ || ( (result[1] ^ result[4]) /* Matching check bytes. */
+ & (result[2] ^ result[5])
+ & (result[3] ^ result[6]) ) != 0xff)
+ {
+ err = gpg_error (GPG_ERR_BAD_PASSPHRASE);
+ goto leave;
+ }
+
+ *r_resultlen = result[0];
+ *r_result = memmove (result, result + 4, result[0]);
+ result = NULL;
+
+ leave:
+ if (result)
+ {
+ wipememory (result, resultlen);
+ xfree (result);
+ }
+ if (passphrase)
+ {
+ wipememory (passphrase, strlen (passphrase));
+ xfree (passphrase);
+ }
+ gcry_cipher_close (encr_hd);
+ xfree (derive_algo_str);
+ xfree (encr_algo_str);
+ xfree (ioarray[0].data);
+ xfree (ioarray[1].data);
+ xfree (ioarray[2].data);
+ xfree (ioarray[3].data);
+ xfree (ioarray[4].data);
+ return err;
+}
+
+
+/* Decrypt the session key and fill in the parm structure. The
+ algo and the IV is expected to be already in PARM. */
+static int
+prepare_decryption (ctrl_t ctrl, const char *hexkeygrip, const char *desc,
+ ksba_const_sexp_t enc_val,
+ struct decrypt_filter_parm_s *parm)
+{
+ char *seskey = NULL;
+ size_t n, seskeylen;
+ int pwri = !hexkeygrip;
+ int rc;
+
+ if (DBG_CRYPTO)
+ log_printcanon ("decrypting:", enc_val, 0);
+
+ if (!pwri)
+ {
+ rc = gpgsm_agent_pkdecrypt (ctrl, hexkeygrip, desc, enc_val,
+ &seskey, &seskeylen);
+ if (rc)
+ {
+ log_error ("error decrypting session key: %s\n", gpg_strerror (rc));
+ goto leave;
+ }
+ }
+
+ n=0;
+ if (pwri) /* Password based encryption. */
+ {
+ gcry_sexp_t s_enc_val;
+ unsigned char *decrypted;
+ unsigned int decryptedlen;
+
+ rc = gcry_sexp_sscan (&s_enc_val, NULL, enc_val,
+ gcry_sexp_canon_len (enc_val, 0, NULL, NULL));
+ if (rc)
+ goto leave;
+
+ rc = pwri_decrypt (ctrl, s_enc_val, &decrypted, &decryptedlen, parm);
+ gcry_sexp_release (s_enc_val);
+ if (rc)
+ goto leave;
+ xfree (seskey);
+ seskey = decrypted;
+ seskeylen = decryptedlen;
+ }
+ else if (seskeylen == 32 || seskeylen == 24 || seskeylen == 16)
+ {
+ /* Smells like an AES-128, 3-DES, or AES-256 key. This might
+ * happen because a SC has already done the unpacking. A better
+ * solution would be to test for this only after we triggered
+ * the GPG_ERR_INV_SESSION_KEY. */
+ }
+ else
+ {
+ if (n + 7 > seskeylen )
+ {
+ rc = gpg_error (GPG_ERR_INV_SESSION_KEY);
+ goto leave;
+ }
+
+ /* FIXME: Actually the leading zero is required but due to the way
+ we encode the output in libgcrypt as an MPI we are not able to
+ encode that leading zero. However, when using a Smartcard we are
+ doing it the right way and therefore we have to skip the zero. This
+ should be fixed in gpg-agent of course. */
+ if (!seskey[n])
+ n++;
+
+ if (seskey[n] != 2 ) /* Wrong block type version. */
+ {
+ rc = gpg_error (GPG_ERR_INV_SESSION_KEY);
+ goto leave;
+ }
+
+ for (n++; n < seskeylen && seskey[n]; n++) /* Skip the random bytes. */
+ ;
+ n++; /* and the zero byte */
+ if (n >= seskeylen )
+ {
+ rc = gpg_error (GPG_ERR_INV_SESSION_KEY);
+ goto leave;
+ }
+ }
+
+ if (DBG_CRYPTO)
+ log_printhex (seskey+n, seskeylen-n, "session key:");
+
+ if (opt.verbose)
+ log_info (_("%s.%s encrypted data\n"),
+ gcry_cipher_algo_name (parm->algo),
+ cipher_mode_to_string (parm->mode));
+
+ rc = gcry_cipher_open (&parm->hd, parm->algo, parm->mode, 0);
+ if (rc)
+ {
+ log_error ("error creating decryptor: %s\n", gpg_strerror (rc));
+ goto leave;
+ }
+
+ rc = gcry_cipher_setkey (parm->hd, seskey+n, seskeylen-n);
+ 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;
+ }
+ if (rc)
+ {
+ log_error("key setup failed: %s\n", gpg_strerror(rc) );
+ goto leave;
+ }
+
+ rc = gcry_cipher_setiv (parm->hd, parm->iv, parm->ivlen);
+ if (rc)
+ {
+ log_error("IV setup failed: %s\n", gpg_strerror(rc) );
+ goto leave;
+ }
+
+ if (parm->mode == GCRY_CIPHER_MODE_GCM)
+ {
+ /* GCM mode really sucks in CMS. We need to know the AAD before
+ * we start decrypting but CMS puts the AAD after the content.
+ * Thus temporary files are required. Let's hope that no real
+ * messages with actual AAD are ever used. OCB Rules! */
+ }
+
+ leave:
+ xfree (seskey);
+ return rc;
+}
+
+
+/* This function is called by the KSBA writer just before the actual
+ write is done. The function must take INLEN bytes from INBUF,
+ decrypt it and store it inoutbuf which has a maximum size of
+ maxoutlen. The valid bytes in outbuf should be return in outlen.
+ Due to different buffer sizes or different length of input and
+ output, it may happen that fewer bytes are processed or fewer bytes
+ are written. */
+static gpg_error_t
+decrypt_filter (void *arg,
+ const void *inbuf, size_t inlen, size_t *inused,
+ void *outbuf, size_t maxoutlen, size_t *outlen)
+{
+ struct decrypt_filter_parm_s *parm = arg;
+ int blklen = parm->blklen;
+ size_t orig_inlen = inlen;
+
+ /* fixme: Should we issue an error when we have not seen one full block? */
+ if (!inlen)
+ return gpg_error (GPG_ERR_BUG);
+
+ if (maxoutlen < 2*parm->blklen)
+ return gpg_error (GPG_ERR_BUG);
+ /* Make some space because we will later need an extra block at the end. */
+ maxoutlen -= blklen;
+
+ if (parm->helpblocklen)
+ {
+ int i, j;
+
+ for (i=parm->helpblocklen,j=0; i < blklen && j < inlen; i++, j++)
+ parm->helpblock[i] = ((const char*)inbuf)[j];
+ inlen -= j;
+ if (blklen > maxoutlen)
+ return gpg_error (GPG_ERR_BUG);
+ if (i < blklen)
+ {
+ parm->helpblocklen = i;
+ *outlen = 0;
+ }
+ else
+ {
+ parm->helpblocklen = 0;
+ if (parm->any_data)
+ {
+ memcpy (outbuf, parm->lastblock, blklen);
+ *outlen =blklen;
+ }
+ else
+ *outlen = 0;
+ gcry_cipher_decrypt (parm->hd, parm->lastblock, blklen,
+ parm->helpblock, blklen);
+ parm->any_data = 1;
+ }
+ *inused = orig_inlen - inlen;
+ return 0;
+ }
+
+
+ if (inlen > maxoutlen)
+ inlen = maxoutlen;
+ if (inlen % blklen)
+ { /* store the remainder away */
+ parm->helpblocklen = inlen%blklen;
+ inlen = inlen/blklen*blklen;
+ memcpy (parm->helpblock, (const char*)inbuf+inlen, parm->helpblocklen);
+ }
+
+ *inused = inlen + parm->helpblocklen;
+ if (inlen)
+ {
+ assert (inlen >= blklen);
+ if (parm->any_data)
+ {
+ gcry_cipher_decrypt (parm->hd, (char*)outbuf+blklen, inlen,
+ inbuf, inlen);
+ memcpy (outbuf, parm->lastblock, blklen);
+ memcpy (parm->lastblock,(char*)outbuf+inlen, blklen);
+ *outlen = inlen;
+ }
+ else
+ {
+ gcry_cipher_decrypt (parm->hd, outbuf, inlen, inbuf, inlen);
+ memcpy (parm->lastblock, (char*)outbuf+inlen-blklen, blklen);
+ *outlen = inlen - blklen;
+ parm->any_data = 1;
+ }
+ }
+ else
+ *outlen = 0;
+ return 0;
+}
+
+
+/* This is the GCM version of decrypt_filter. */
+static gpg_error_t
+decrypt_gcm_filter (void *arg,
+ const void *inbuf, size_t inlen, size_t *inused,
+ void *outbuf, size_t maxoutlen, size_t *outlen)
+{
+ struct decrypt_filter_parm_s *parm = arg;
+
+ if (!inlen)
+ return gpg_error (GPG_ERR_BUG);
+
+ if (maxoutlen < parm->blklen)
+ return gpg_error (GPG_ERR_BUG);
+
+ if (inlen > maxoutlen)
+ inlen = maxoutlen;
+
+ *inused = inlen;
+ if (inlen)
+ {
+ gcry_cipher_decrypt (parm->hd, outbuf, inlen, inbuf, inlen);
+ *outlen = inlen;
+ parm->any_data = 1;
+ }
+ else
+ *outlen = 0;
+ return 0;
+}
+
+
+
+/* Perform a decrypt operation. */
+int
+gpgsm_decrypt (ctrl_t ctrl, int in_fd, estream_t out_fp)
+{
+ int rc;
+ gnupg_ksba_io_t b64reader = NULL;
+ gnupg_ksba_io_t b64writer = NULL;
+ ksba_reader_t reader;
+ ksba_writer_t writer;
+ ksba_cms_t cms = NULL;
+ ksba_stop_reason_t stopreason;
+ KEYDB_HANDLE kh;
+ int recp;
+ estream_t in_fp = NULL;
+ struct decrypt_filter_parm_s dfparm;
+
+ memset (&dfparm, 0, sizeof dfparm);
+
+ audit_set_type (ctrl->audit, AUDIT_TYPE_DECRYPT);
+
+ kh = keydb_new ();
+ if (!kh)
+ {
+ log_error (_("failed to allocate keyDB handle\n"));
+ rc = gpg_error (GPG_ERR_GENERAL);
+ goto leave;
+ }
+
+ in_fp = es_fdopen_nc (in_fd, "rb");
+ if (!in_fp)
+ {
+ rc = gpg_error_from_syserror ();
+ log_error ("fdopen() failed: %s\n", strerror (errno));
+ goto leave;
+ }
+
+ rc = gnupg_ksba_create_reader
+ (&b64reader, ((ctrl->is_pem? GNUPG_KSBA_IO_PEM : 0)
+ | (ctrl->is_base64? GNUPG_KSBA_IO_BASE64 : 0)
+ | (ctrl->autodetect_encoding? GNUPG_KSBA_IO_AUTODETECT : 0)),
+ in_fp, &reader);
+ if (rc)
+ {
+ log_error ("can't create reader: %s\n", gpg_strerror (rc));
+ goto leave;
+ }
+
+ rc = gnupg_ksba_create_writer
+ (&b64writer, ((ctrl->create_pem? GNUPG_KSBA_IO_PEM : 0)
+ | (ctrl->create_base64? GNUPG_KSBA_IO_BASE64 : 0)),
+ ctrl->pem_name, out_fp, &writer);
+ if (rc)
+ {
+ log_error ("can't create writer: %s\n", gpg_strerror (rc));
+ goto leave;
+ }
+
+ rc = ksba_cms_new (&cms);
+ if (rc)
+ goto leave;
+
+ rc = ksba_cms_set_reader_writer (cms, reader, writer);
+ if (rc)
+ {
+ log_debug ("ksba_cms_set_reader_writer failed: %s\n",
+ gpg_strerror (rc));
+ goto leave;
+ }
+
+ audit_log (ctrl->audit, AUDIT_SETUP_READY);
+
+ /* Parser loop. */
+ do
+ {
+ rc = ksba_cms_parse (cms, &stopreason);
+ if (rc)
+ {
+ log_debug ("ksba_cms_parse failed: %s\n", gpg_strerror (rc));
+ goto leave;
+ }
+
+ if (stopreason == KSBA_SR_BEGIN_DATA
+ || stopreason == KSBA_SR_DETACHED_DATA)
+ {
+ int algo, mode;
+ const char *algoid;
+ int any_key = 0;
+
+ audit_log (ctrl->audit, AUDIT_GOT_DATA);
+
+ algoid = ksba_cms_get_content_oid (cms, 2/* encryption algo*/);
+ algo = gcry_cipher_map_name (algoid);
+ mode = gcry_cipher_mode_from_oid (algoid);
+ if (!algo || !mode)
+ {
+ rc = gpg_error (GPG_ERR_UNSUPPORTED_ALGORITHM);
+ log_error ("unsupported algorithm '%s'\n", algoid? algoid:"?");
+ if (algoid && !strcmp (algoid, "1.2.840.113549.3.2"))
+ log_info (_("(this is the RC2 algorithm)\n"));
+ else if (!algoid)
+ log_info (_("(this does not seem to be an encrypted"
+ " message)\n"));
+ {
+ char numbuf[50];
+ sprintf (numbuf, "%d", rc);
+ gpgsm_status2 (ctrl, STATUS_ERROR, "decrypt.algorithm",
+ numbuf, algoid?algoid:"?", NULL);
+ audit_log_s (ctrl->audit, AUDIT_BAD_DATA_CIPHER_ALGO, algoid);
+ }
+
+ /* If it seems that this is not an encrypted message we
+ return a more sensible error code. */
+ if (!algoid)
+ rc = gpg_error (GPG_ERR_NO_DATA);
+
+ goto leave;
+ }
+
+ /* Check compliance. */
+ if (! gnupg_cipher_is_allowed (opt.compliance, 0, algo, mode))
+ {
+ log_error (_("cipher algorithm '%s'"
+ " may not be used in %s mode\n"),
+ gcry_cipher_algo_name (algo),
+ gnupg_compliance_option_string (opt.compliance));
+ rc = gpg_error (GPG_ERR_CIPHER_ALGO);
+ goto leave;
+ }
+
+ /* For CMS, CO_DE_VS demands CBC mode. */
+ dfparm.is_de_vs = gnupg_cipher_is_compliant (CO_DE_VS, algo, mode);
+
+ audit_log_i (ctrl->audit, AUDIT_DATA_CIPHER_ALGO, algo);
+ dfparm.algo = algo;
+ dfparm.mode = mode;
+ dfparm.blklen = gcry_cipher_get_algo_blklen (algo);
+ if (dfparm.blklen > sizeof (dfparm.helpblock))
+ return gpg_error (GPG_ERR_BUG);
+
+ rc = ksba_cms_get_content_enc_iv (cms,
+ dfparm.iv,
+ sizeof (dfparm.iv),
+ &dfparm.ivlen);
+ if (rc)
+ {
+ log_error ("error getting IV: %s\n", gpg_strerror (rc));
+ goto leave;
+ }
+
+ for (recp=0; !any_key; recp++)
+ {
+ char *issuer;
+ ksba_sexp_t serial;
+ ksba_sexp_t enc_val;
+ char *hexkeygrip = NULL;
+ char *pkalgostr = NULL;
+ char *pkfpr = NULL;
+ char *desc = NULL;
+ char kidbuf[16+1];
+ int tmp_rc;
+ ksba_cert_t cert = NULL;
+ unsigned int nbits;
+ int pk_algo = 0;
+ int maybe_pwri = 0;
+
+ *kidbuf = 0;
+
+ tmp_rc = ksba_cms_get_issuer_serial (cms, recp, &issuer, &serial);
+ if (tmp_rc == -1 && recp)
+ break; /* no more recipients */
+ audit_log_i (ctrl->audit, AUDIT_NEW_RECP, recp);
+ if (gpg_err_code (tmp_rc) == GPG_ERR_UNSUPPORTED_CMS_OBJ)
+ {
+ maybe_pwri = 1;
+ }
+ else if (tmp_rc)
+ {
+ log_error ("recp %d - error getting info: %s\n",
+ recp, gpg_strerror (tmp_rc));
+ }
+ else
+ {
+ if (opt.verbose)
+ {
+ log_debug ("recp %d - issuer: '%s'\n",
+ recp, issuer? issuer:"[NONE]");
+ log_debug ("recp %d - serial: ", recp);
+ gpgsm_dump_serial (serial);
+ log_printf ("\n");
+ }
+
+ if (ctrl->audit)
+ {
+ char *tmpstr = gpgsm_format_sn_issuer (serial, issuer);
+ audit_log_s (ctrl->audit, AUDIT_RECP_NAME, tmpstr);
+ xfree (tmpstr);
+ }
+
+ keydb_search_reset (kh);
+ rc = keydb_search_issuer_sn (ctrl, kh, issuer, serial);
+ if (rc)
+ {
+ log_error ("failed to find the certificate: %s\n",
+ gpg_strerror(rc));
+ goto oops;
+ }
+
+ rc = keydb_get_cert (kh, &cert);
+ if (rc)
+ {
+ log_error ("failed to get cert: %s\n", gpg_strerror (rc));
+ goto oops;
+ }
+
+ /* Print the ENC_TO status line. Note that we can
+ do so only if we have the certificate. This is
+ in contrast to gpg where the keyID is commonly
+ included in the encrypted messages. It is too
+ cumbersome to retrieve the used algorithm, thus
+ we don't print it for now. We also record the
+ keyid for later use. */
+ {
+ unsigned long kid[2];
+
+ kid[0] = gpgsm_get_short_fingerprint (cert, kid+1);
+ snprintf (kidbuf, sizeof kidbuf, "%08lX%08lX",
+ kid[1], kid[0]);
+ gpgsm_status2 (ctrl, STATUS_ENC_TO,
+ kidbuf, "0", "0", NULL);
+ }
+
+ /* Put the certificate into the audit log. */
+ audit_log_cert (ctrl->audit, AUDIT_SAVE_CERT, cert, 0);
+
+ /* Just in case there is a problem with the own
+ certificate we print this message - should never
+ happen of course */
+ rc = gpgsm_cert_use_decrypt_p (cert);
+ if (rc)
+ {
+ char numbuf[50];
+ sprintf (numbuf, "%d", rc);
+ gpgsm_status2 (ctrl, STATUS_ERROR, "decrypt.keyusage",
+ numbuf, NULL);
+ rc = 0;
+ }
+
+ hexkeygrip = gpgsm_get_keygrip_hexstring (cert);
+ desc = gpgsm_format_keydesc (cert);
+ pkfpr = gpgsm_get_fingerprint_hexstring (cert, GCRY_MD_SHA1);
+ pkalgostr = gpgsm_pubkey_algo_string (cert, NULL);
+ pk_algo = gpgsm_get_key_algo_info (cert, &nbits);
+ if (!opt.quiet)
+ log_info (_("encrypted to %s key %s\n"), pkalgostr, pkfpr);
+
+ /* Check compliance. */
+ if (!gnupg_pk_is_allowed (opt.compliance,
+ PK_USE_DECRYPTION,
+ pk_algo, 0, NULL, nbits, NULL))
+ {
+ char kidstr[10+1];
+
+ snprintf (kidstr, sizeof kidstr, "0x%08lX",
+ gpgsm_get_short_fingerprint (cert, NULL));
+ log_info (_("key %s is not suitable for decryption"
+ " in %s mode\n"),
+ kidstr,
+ gnupg_compliance_option_string(opt.compliance));
+ rc = gpg_error (GPG_ERR_PUBKEY_ALGO);
+ goto oops;
+ }
+
+ /* Check that all certs are compliant with CO_DE_VS. */
+ dfparm.is_de_vs =
+ (dfparm.is_de_vs
+ && gnupg_pk_is_compliant (CO_DE_VS, pk_algo, 0,
+ NULL, nbits, NULL));
+
+ oops:
+ if (rc)
+ {
+ /* We cannot check compliance of certs that we
+ * don't have. */
+ dfparm.is_de_vs = 0;
+ }
+ xfree (issuer);
+ xfree (serial);
+ ksba_cert_release (cert);
+ }
+
+ if ((!hexkeygrip || !pk_algo) && !maybe_pwri)
+ ;
+ else if (!(enc_val = ksba_cms_get_enc_val (cms, recp)))
+ {
+ log_error ("recp %d - error getting encrypted session key\n",
+ recp);
+ if (maybe_pwri)
+ log_info ("(possibly unsupported KEK info)\n");
+ }
+ else
+ {
+ if (maybe_pwri && opt.verbose)
+ log_info ("recp %d - KEKRI or PWRI\n", recp);
+
+ rc = prepare_decryption (ctrl, hexkeygrip,
+ desc, enc_val, &dfparm);
+ xfree (enc_val);
+ if (rc)
+ {
+ log_info ("decrypting session key failed: %s\n",
+ gpg_strerror (rc));
+ if (gpg_err_code (rc) == GPG_ERR_NO_SECKEY && *kidbuf)
+ gpgsm_status2 (ctrl, STATUS_NO_SECKEY, kidbuf, NULL);
+ }
+ else
+ { /* setup the bulk decrypter */
+ any_key = 1;
+ ksba_writer_set_filter
+ (writer,
+ dfparm.mode == GCRY_CIPHER_MODE_GCM?
+ decrypt_gcm_filter : decrypt_filter,
+ &dfparm);
+
+ if (dfparm.is_de_vs
+ && gnupg_gcrypt_is_compliant (CO_DE_VS))
+ gpgsm_status (ctrl, STATUS_DECRYPTION_COMPLIANCE_MODE,
+ gnupg_status_compliance_flag (CO_DE_VS));
+ else if (opt.require_compliance
+ && opt.compliance == CO_DE_VS)
+ {
+ log_error (_("operation forced to fail due to"
+ " unfulfilled compliance rules\n"));
+ gpgsm_errors_seen = 1;
+ }
+ }
+ audit_log_ok (ctrl->audit, AUDIT_RECP_RESULT, rc);
+ }
+ xfree (pkalgostr);
+ xfree (pkfpr);
+ xfree (hexkeygrip);
+ xfree (desc);
+ }
+
+ /* If we write an audit log add the unused recipients to the
+ log as well. */
+ if (ctrl->audit && any_key)
+ {
+ for (;; recp++)
+ {
+ char *issuer;
+ ksba_sexp_t serial;
+ int tmp_rc;
+
+ tmp_rc = ksba_cms_get_issuer_serial (cms, recp,
+ &issuer, &serial);
+ if (tmp_rc == -1)
+ break; /* no more recipients */
+ audit_log_i (ctrl->audit, AUDIT_NEW_RECP, recp);
+ if (tmp_rc)
+ log_error ("recp %d - error getting info: %s\n",
+ recp, gpg_strerror (rc));
+ else
+ {
+ char *tmpstr = gpgsm_format_sn_issuer (serial, issuer);
+ audit_log_s (ctrl->audit, AUDIT_RECP_NAME, tmpstr);
+ xfree (tmpstr);
+ xfree (issuer);
+ xfree (serial);
+ }
+ }
+ }
+
+ if (!any_key)
+ {
+ rc = gpg_error (GPG_ERR_NO_SECKEY);
+ goto leave;
+ }
+ }
+ else if (stopreason == KSBA_SR_END_DATA)
+ {
+ ksba_writer_set_filter (writer, NULL, NULL);
+ if (dfparm.mode == GCRY_CIPHER_MODE_GCM)
+ {
+ /* Nothing yet to do. We wait for the ready event. */
+ }
+ else if (dfparm.any_data )
+ { /* write the last block with padding removed */
+ int i, npadding = dfparm.lastblock[dfparm.blklen-1];
+ if (!npadding || npadding > dfparm.blklen)
+ {
+ log_error ("invalid padding with value %d\n", npadding);
+ rc = gpg_error (GPG_ERR_INV_DATA);
+ goto leave;
+ }
+ rc = ksba_writer_write (writer,
+ dfparm.lastblock,
+ dfparm.blklen - npadding);
+ if (rc)
+ goto leave;
+
+ for (i=dfparm.blklen - npadding; i < dfparm.blklen; i++)
+ {
+ if (dfparm.lastblock[i] != npadding)
+ {
+ log_error ("inconsistent padding\n");
+ rc = gpg_error (GPG_ERR_INV_DATA);
+ goto leave;
+ }
+ }
+ }
+ }
+ else if (stopreason == KSBA_SR_READY)
+ {
+ if (dfparm.mode == GCRY_CIPHER_MODE_GCM)
+ {
+ char *authtag;
+ size_t authtaglen;
+
+ rc = ksba_cms_get_message_digest (cms, 0, &authtag, &authtaglen);
+ if (rc)
+ {
+ log_error ("error getting authtag: %s\n", gpg_strerror (rc));
+ goto leave;
+ }
+ if (DBG_CRYPTO)
+ log_printhex (authtag, authtaglen, "Authtag ...:");
+ rc = gcry_cipher_checktag (dfparm.hd, authtag, authtaglen);
+ xfree (authtag);
+ if (rc)
+ log_error ("data is not authentic: %s\n", gpg_strerror (rc));
+ goto leave;
+ }
+ }
+ }
+ while (stopreason != KSBA_SR_READY);
+
+ rc = gnupg_ksba_finish_writer (b64writer);
+ if (rc)
+ {
+ log_error ("write failed: %s\n", gpg_strerror (rc));
+ goto leave;
+ }
+ gpgsm_status (ctrl, STATUS_DECRYPTION_OKAY, NULL);
+
+
+ leave:
+ audit_log_ok (ctrl->audit, AUDIT_DECRYPTION_RESULT, rc);
+ if (rc)
+ {
+ gpgsm_status (ctrl, STATUS_DECRYPTION_FAILED, NULL);
+ log_error ("message decryption failed: %s <%s>\n",
+ gpg_strerror (rc), gpg_strsource (rc));
+ }
+ ksba_cms_release (cms);
+ gnupg_ksba_destroy_reader (b64reader);
+ gnupg_ksba_destroy_writer (b64writer);
+ keydb_release (kh);
+ es_fclose (in_fp);
+ if (dfparm.hd)
+ gcry_cipher_close (dfparm.hd);
+ return rc;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-05-17 15:54:01 +0000