diff options
Diffstat (limited to '')
| -rw-r--r-- | sm/sign.c | 700 |
1 files changed, 700 insertions, 0 deletions
diff --git a/sm/sign.c b/sm/sign.c new file mode 100644 index 000000000..d656825e8 --- /dev/null +++ b/sm/sign.c @@ -0,0 +1,700 @@ +/* sign.c - Sign a message + * Copyright (C) 2001, 2002, 2003 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 2 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, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, + * USA. + */ + +#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 "i18n.h" + + +static void +hash_data (int fd, gcry_md_hd_t md) +{ + FILE *fp; + char buffer[4096]; + int nread; + + fp = fdopen ( dup (fd), "rb"); + if (!fp) + { + log_error ("fdopen(%d) failed: %s\n", fd, strerror (errno)); + return; + } + + do + { + nread = fread (buffer, 1, DIM(buffer), fp); + gcry_md_write (md, buffer, nread); + } + while (nread); + if (ferror (fp)) + log_error ("read error on fd %d: %s\n", fd, strerror (errno)); + fclose (fp); +} + +static int +hash_and_copy_data (int fd, gcry_md_hd_t md, ksba_writer_t writer) +{ + gpg_error_t err; + FILE *fp; + char buffer[4096]; + int nread; + int rc = 0; + int any = 0; + + fp = fdopen ( dup (fd), "rb"); + if (!fp) + { + gpg_error_t tmperr = gpg_error (gpg_err_code_from_errno (errno)); + log_error ("fdopen(%d) failed: %s\n", fd, strerror (errno)); + return tmperr; + } + + do + { + nread = fread (buffer, 1, DIM(buffer), fp); + if (nread) + { + any = 1; + gcry_md_write (md, buffer, nread); + err = ksba_writer_write_octet_string (writer, buffer, nread, 0); + if (err) + { + log_error ("write failed: %s\n", gpg_strerror (err)); + rc = err; + } + } + } + while (nread && !rc); + if (ferror (fp)) + { + rc = gpg_error (gpg_err_code_from_errno (errno)); + log_error ("read error on fd %d: %s\n", fd, strerror (errno)); + } + fclose (fp); + if (!any) + { + /* We can't allow to sign an empty message because it does not + make much sense and more seriously, ksba-cms_build has + already written the tag for data and now expects an octet + string but an octet string of zeize 0 is illegal. */ + log_error ("cannot sign an empty message\n"); + rc = gpg_error (GPG_ERR_NO_DATA); + } + if (!rc) + { + err = ksba_writer_write_octet_string (writer, NULL, 0, 1); + if (err) + { + log_error ("write failed: %s\n", gpg_strerror (err)); + rc = err; + } + } + + return rc; +} + + +/* Get the default certificate which is defined as the first one our + keyDB returns and has a secret key available. */ +int +gpgsm_get_default_cert (ctrl_t ctrl, ksba_cert_t *r_cert) +{ + KEYDB_HANDLE hd; + ksba_cert_t cert = NULL; + int rc; + char *p; + + hd = keydb_new (0); + if (!hd) + return gpg_error (GPG_ERR_GENERAL); + rc = keydb_search_first (hd); + if (rc) + { + keydb_release (hd); + return rc; + } + + do + { + rc = keydb_get_cert (hd, &cert); + if (rc) + { + log_error ("keydb_get_cert failed: %s\n", gpg_strerror (rc)); + keydb_release (hd); + return rc; + } + + p = gpgsm_get_keygrip_hexstring (cert); + if (p) + { + if (!gpgsm_agent_havekey (ctrl, p)) + { + xfree (p); + keydb_release (hd); + *r_cert = cert; + return 0; /* got it */ + } + xfree (p); + } + + ksba_cert_release (cert); + cert = NULL; + } + while (!(rc = keydb_search_next (hd))); + if (rc && rc != -1) + log_error ("keydb_search_next failed: %s\n", gpg_strerror (rc)); + + ksba_cert_release (cert); + keydb_release (hd); + return rc; +} + + +static ksba_cert_t +get_default_signer (ctrl_t ctrl) +{ + KEYDB_SEARCH_DESC desc; + ksba_cert_t cert = NULL; + KEYDB_HANDLE kh = NULL; + int rc; + + if (!opt.local_user) + { + rc = gpgsm_get_default_cert (ctrl, &cert); + if (rc) + { + if (rc != -1) + log_debug ("failed to find default certificate: %s\n", + gpg_strerror (rc)); + return NULL; + } + return cert; + } + + rc = keydb_classify_name (opt.local_user, &desc); + if (rc) + { + log_error ("failed to find default signer: %s\n", gpg_strerror (rc)); + return NULL; + } + + kh = keydb_new (0); + if (!kh) + return NULL; + + rc = keydb_search (kh, &desc, 1); + if (rc) + { + log_debug ("failed to find default certificate: rc=%d\n", rc); + } + else + { + rc = keydb_get_cert (kh, &cert); + if (rc) + { + log_debug ("failed to get cert: rc=%d\n", rc); + } + } + + keydb_release (kh); + return cert; +} + +/* Depending on the options in CTRL add the certificate CERT as well as + other certificate up in the chain to the Root-CA to the CMS + object. */ +static int +add_certificate_list (CTRL ctrl, ksba_cms_t cms, ksba_cert_t cert) +{ + gpg_error_t err; + int rc = 0; + ksba_cert_t next = NULL; + int n; + int not_root = 0; + + ksba_cert_ref (cert); + + n = ctrl->include_certs; + log_debug ("adding certificates at level %d\n", n); + if (n == -2) + { + not_root = 1; + n = -1; + } + if (n < 0 || n > 50) + n = 50; /* We better apply an upper bound */ + + /* First add my own certificate unless we don't want any certificate + included at all. */ + if (n) + { + if (not_root && gpgsm_is_root_cert (cert)) + err = 0; + else + err = ksba_cms_add_cert (cms, cert); + if (err) + goto ksba_failure; + if (n>0) + n--; + } + /* Walk the chain to include all other certificates. Note that a -1 + used for N makes sure that there is no limit and all certs get + included. */ + while ( n-- && !(rc = gpgsm_walk_cert_chain (cert, &next)) ) + { + if (not_root && gpgsm_is_root_cert (next)) + err = 0; + else + err = ksba_cms_add_cert (cms, next); + ksba_cert_release (cert); + cert = next; next = NULL; + if (err) + goto ksba_failure; + } + ksba_cert_release (cert); + + return rc == -1? 0: rc; + + ksba_failure: + ksba_cert_release (cert); + log_error ("ksba_cms_add_cert failed: %s\n", gpg_strerror (err)); + return err; +} + + + + +/* Perform a sign operation. + + Sign the data received on DATA-FD in embedded mode or in detached + mode when DETACHED is true. Write the signature to OUT_FP. The + keys used to sign are taken from SIGNERLIST or the default one will + be used if the value of this argument is NULL. */ +int +gpgsm_sign (CTRL ctrl, CERTLIST signerlist, + int data_fd, int detached, FILE *out_fp) +{ + int i, rc; + gpg_error_t err; + Base64Context b64writer = NULL; + ksba_writer_t writer; + ksba_cms_t cms = NULL; + ksba_stop_reason_t stopreason; + KEYDB_HANDLE kh = NULL; + gcry_md_hd_t data_md = NULL; + int signer; + const char *algoid; + int algo; + ksba_isotime_t signed_at; + CERTLIST cl; + int release_signerlist = 0; + + kh = keydb_new (0); + if (!kh) + { + log_error (_("failed to allocated keyDB handle\n")); + rc = gpg_error (GPG_ERR_GENERAL); + goto leave; + } + + ctrl->pem_name = "SIGNED MESSAGE"; + rc = gpgsm_create_writer (&b64writer, ctrl, out_fp, &writer); + if (rc) + { + log_error ("can't create writer: %s\n", gpg_strerror (rc)); + goto leave; + } + + err = ksba_cms_new (&cms); + if (err) + { + rc = err; + goto leave; + } + + err = ksba_cms_set_reader_writer (cms, NULL, writer); + if (err) + { + log_debug ("ksba_cms_set_reader_writer failed: %s\n", + gpg_strerror (err)); + rc = err; + goto leave; + } + + /* We are going to create signed data with data as encap. content */ + err = ksba_cms_set_content_type (cms, 0, KSBA_CT_SIGNED_DATA); + if (!err) + err = ksba_cms_set_content_type (cms, 1, KSBA_CT_DATA); + if (err) + { + log_debug ("ksba_cms_set_content_type failed: %s\n", + gpg_strerror (err)); + rc = err; + goto leave; + } + + /* If no list of signers is given, use a default one. */ + if (!signerlist) + { + ksba_cert_t cert = get_default_signer (ctrl); + if (!cert) + { + log_error ("no default signer found\n"); + rc = gpg_error (GPG_ERR_GENERAL); + goto leave; + } + + /* Although we don't check for ambigious specification we will + check that the signer's certificate is is usable and + valid. */ + rc = gpgsm_cert_use_sign_p (cert); + if (!rc) + rc = gpgsm_validate_chain (ctrl, cert, NULL, 0, NULL, 0); + if (rc) + goto leave; + + /* That one is fine - create signerlist. */ + signerlist = xtrycalloc (1, sizeof *signerlist); + if (!signerlist) + { + rc = OUT_OF_CORE (errno); + ksba_cert_release (cert); + goto leave; + } + signerlist->cert = cert; + release_signerlist = 1; + } + + + /* Gather certificates of signers and store them in the CMS object. */ + for (cl=signerlist; cl; cl = cl->next) + { + rc = gpgsm_cert_use_sign_p (cl->cert); + if (rc) + goto leave; + + err = ksba_cms_add_signer (cms, cl->cert); + if (err) + { + log_error ("ksba_cms_add_signer failed: %s\n", gpg_strerror (err)); + rc = err; + goto leave; + } + rc = add_certificate_list (ctrl, cms, cl->cert); + if (rc) + { + log_error ("failed to store list of certificates: %s\n", + gpg_strerror(rc)); + goto leave; + } + /* Set the hash algorithm we are going to use */ + err = ksba_cms_add_digest_algo (cms, "1.3.14.3.2.26" /*SHA-1*/); + if (err) + { + log_debug ("ksba_cms_add_digest_algo failed: %s\n", + gpg_strerror (err)); + rc = err; + goto leave; + } + } + + + /* Check whether one of the certificates is qualified. Note that we + already validated the certificate and thus the user data stored + flag must be available. */ + for (cl=signerlist; cl; cl = cl->next) + { + size_t buflen; + char buffer[1]; + + err = ksba_cert_get_user_data (cl->cert, "is_qualified", + &buffer, sizeof (buffer), &buflen); + if (err || !buflen) + { + log_error (_("checking for qualified certificate failed: %s\n"), + gpg_strerror (err)); + rc = err; + goto leave; + } + if (*buffer) + err = gpgsm_qualified_consent (ctrl, cl->cert); + else + err = gpgsm_not_qualified_warning (ctrl, cl->cert); + if (err) + { + rc = err; + goto leave; + } + } + + /* Prepare hashing (actually we are figuring out what we have set above)*/ + rc = gcry_md_open (&data_md, 0, 0); + if (rc) + { + log_error ("md_open failed: %s\n", gpg_strerror (rc)); + goto leave; + } + if (DBG_HASHING) + gcry_md_start_debug (data_md, "sign.data"); + + for (i=0; (algoid=ksba_cms_get_digest_algo_list (cms, i)); i++) + { + algo = gcry_md_map_name (algoid); + if (!algo) + { + log_error ("unknown hash algorithm `%s'\n", algoid? algoid:"?"); + if (algoid + && ( !strcmp (algoid, "1.2.840.113549.1.1.2") + ||!strcmp (algoid, "1.2.840.113549.2.2"))) + log_info (_("(this is the MD2 algorithm)\n")); + rc = gpg_error (GPG_ERR_BUG); + goto leave; + } + gcry_md_enable (data_md, algo); + } + + if (detached) + { /* we hash the data right now so that we can store the message + digest. ksba_cms_build() takes this as an flag that detached + data is expected. */ + unsigned char *digest; + size_t digest_len; + /* Fixme do this for all signers and get the algo to use from + the signer's certificate - does not make mich sense, but we + should do this consistent as we have already done it above. */ + algo = GCRY_MD_SHA1; + hash_data (data_fd, data_md); + digest = gcry_md_read (data_md, algo); + digest_len = gcry_md_get_algo_dlen (algo); + if ( !digest || !digest_len) + { + log_error ("problem getting the hash of the data\n"); + rc = gpg_error (GPG_ERR_BUG); + goto leave; + } + for (cl=signerlist,signer=0; cl; cl = cl->next, signer++) + { + err = ksba_cms_set_message_digest (cms, signer, digest, digest_len); + if (err) + { + log_error ("ksba_cms_set_message_digest failed: %s\n", + gpg_strerror (err)); + rc = err; + goto leave; + } + } + } + + gnupg_get_isotime (signed_at); + for (cl=signerlist,signer=0; cl; cl = cl->next, signer++) + { + err = ksba_cms_set_signing_time (cms, signer, signed_at); + if (err) + { + log_error ("ksba_cms_set_signing_time failed: %s\n", + gpg_strerror (err)); + rc = err; + goto leave; + } + } + + /* We need to write at least a minimal list of our capabilities to + try to convince some MUAs to use 3DEs and not the crippled + RC2. Our list is: + + aes128-CBC + des-EDE3-CBC + */ + err = ksba_cms_add_smime_capability (cms, "2.16.840.1.101.3.4.1.2", NULL, 0); + if (!err) + err = ksba_cms_add_smime_capability (cms, "1.2.840.113549.3.7", NULL, 0); + if (err) + { + log_error ("ksba_cms_add_smime_capability failed: %s\n", + gpg_strerror (err)); + goto leave; + } + + + /* Main building loop. */ + do + { + err = ksba_cms_build (cms, &stopreason); + if (err) + { + log_debug ("ksba_cms_build failed: %s\n", gpg_strerror (err)); + rc = err; + goto leave; + } + + if (stopreason == KSBA_SR_BEGIN_DATA) + { /* hash the data and store the message digest */ + unsigned char *digest; + size_t digest_len; + + assert (!detached); + /* Fixme: get the algo to use from the signer's certificate + - does not make much sense, but we should do this + consistent as we have already done it above. Code is + mostly duplicated above. */ + + algo = GCRY_MD_SHA1; + rc = hash_and_copy_data (data_fd, data_md, writer); + if (rc) + goto leave; + digest = gcry_md_read (data_md, algo); + digest_len = gcry_md_get_algo_dlen (algo); + if ( !digest || !digest_len) + { + log_error ("problem getting the hash of the data\n"); + rc = gpg_error (GPG_ERR_BUG); + goto leave; + } + for (cl=signerlist,signer=0; cl; cl = cl->next, signer++) + { + err = ksba_cms_set_message_digest (cms, signer, + digest, digest_len); + if (err) + { + log_error ("ksba_cms_set_message_digest failed: %s\n", + gpg_strerror (err)); + rc = err; + goto leave; + } + } + } + else if (stopreason == KSBA_SR_NEED_SIG) + { /* calculate the signature for all signers */ + gcry_md_hd_t md; + + algo = GCRY_MD_SHA1; + rc = gcry_md_open (&md, algo, 0); + if (rc) + { + log_error ("md_open failed: %s\n", gpg_strerror (rc)); + goto leave; + } + if (DBG_HASHING) + gcry_md_start_debug (md, "sign.attr"); + ksba_cms_set_hash_function (cms, HASH_FNC, md); + for (cl=signerlist,signer=0; cl; cl = cl->next, signer++) + { + unsigned char *sigval = NULL; + char *buf, *fpr; + + if (signer) + gcry_md_reset (md); + rc = ksba_cms_hash_signed_attrs (cms, signer); + if (rc) + { + log_debug ("hashing signed attrs failed: %s\n", + gpg_strerror (rc)); + gcry_md_close (md); + goto leave; + } + + rc = gpgsm_create_cms_signature (ctrl, cl->cert, + md, algo, &sigval); + if (rc) + { + gcry_md_close (md); + goto leave; + } + + err = ksba_cms_set_sig_val (cms, signer, sigval); + xfree (sigval); + if (err) + { + log_error ("failed to store the signature: %s\n", + gpg_strerror (err)); + rc = err; + gcry_md_close (md); + goto leave; + } + + /* write a status message */ + fpr = gpgsm_get_fingerprint_hexstring (cl->cert, GCRY_MD_SHA1); + if (!fpr) + { + rc = gpg_error (GPG_ERR_ENOMEM); + gcry_md_close (md); + goto leave; + } + { + int pkalgo = gpgsm_get_key_algo_info (cl->cert, NULL); + rc = asprintf (&buf, "%c %d %d 00 %s %s", + detached? 'D':'S', + pkalgo, + algo, + signed_at, + fpr); + } + xfree (fpr); + if (rc < 0) + { + rc = gpg_error (GPG_ERR_ENOMEM); + gcry_md_close (md); + goto leave; + } + rc = 0; + gpgsm_status (ctrl, STATUS_SIG_CREATED, buf); + free (buf); /* yes, we must use the regular free() here */ + } + gcry_md_close (md); + + } + } + while (stopreason != KSBA_SR_READY); + + rc = gpgsm_finish_writer (b64writer); + if (rc) + { + log_error ("write failed: %s\n", gpg_strerror (rc)); + goto leave; + } + + log_info ("signature created\n"); + + + leave: + if (rc) + log_error ("error creating signature: %s <%s>\n", + gpg_strerror (rc), gpg_strsource (rc) ); + if (release_signerlist) + gpgsm_release_certlist (signerlist); + ksba_cms_release (cms); + gpgsm_destroy_writer (b64writer); + keydb_release (kh); + gcry_md_close (data_md); + return rc; +} |