/* sign.c - Sign a message * Copyright (C) 2001, 2002, 2003, 2008, * 2010 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 . */ #include #include #include #include #include #include #include #include #include "gpgsm.h" #include #include #include "keydb.h" #include "../common/i18n.h" /* Hash the data and return if something was hashed. Return -1 on error. */ static int hash_data (int fd, gcry_md_hd_t md) { estream_t fp; char buffer[4096]; int nread; int rc = 0; fp = es_fdopen_nc (fd, "rb"); if (!fp) { log_error ("fdopen(%d) failed: %s\n", fd, strerror (errno)); return -1; } do { nread = es_fread (buffer, 1, DIM(buffer), fp); gcry_md_write (md, buffer, nread); } while (nread); if (es_ferror (fp)) { log_error ("read error on fd %d: %s\n", fd, strerror (errno)); rc = -1; } es_fclose (fp); return rc; } static int hash_and_copy_data (int fd, gcry_md_hd_t md, ksba_writer_t writer) { gpg_error_t err; estream_t fp; char buffer[4096]; int nread; int rc = 0; int any = 0; fp = es_fdopen_nc (fd, "rb"); if (!fp) { gpg_error_t tmperr = gpg_error_from_syserror (); log_error ("fdopen(%d) failed: %s\n", fd, strerror (errno)); return tmperr; } do { nread = es_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 (es_ferror (fp)) { rc = gpg_error_from_syserror (); log_error ("read error on fd %d: %s\n", fd, strerror (errno)); } es_fclose (fp); if (!any) { /* We can't allow signing 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 and an octet string of size 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 certificate capable of signing returned by the keyDB 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 (); if (!hd) return gpg_error (GPG_ERR_GENERAL); rc = keydb_search_first (ctrl, 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; } if (!gpgsm_cert_use_sign_p (cert)) { 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 (ctrl, 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 = classify_user_id (opt.local_user, &desc, 0); if (rc) { log_error ("failed to find default signer: %s\n", gpg_strerror (rc)); return NULL; } kh = keydb_new (); if (!kh) return NULL; rc = keydb_search (ctrl, 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_t 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 (ctrl, 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_t ctrl, certlist_t signerlist, int data_fd, int detached, estream_t out_fp) { int i, rc; gpg_error_t err; gnupg_ksba_io_t 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_t cl; int release_signerlist = 0; audit_set_type (ctrl->audit, AUDIT_TYPE_SIGN); kh = keydb_new (); if (!kh) { log_error (_("failed to allocate keyDB handle\n")); rc = gpg_error (GPG_ERR_GENERAL); goto leave; } if (!gnupg_rng_is_compliant (opt.compliance)) { rc = gpg_error (GPG_ERR_FORBIDDEN); log_error (_("%s is not compliant with %s mode\n"), "RNG", gnupg_compliance_option_string (opt.compliance)); gpgsm_status_with_error (ctrl, STATUS_ERROR, "random-compliance", rc); goto leave; } ctrl->pem_name = "SIGNED MESSAGE"; 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; } 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 the default certificate. */ if (!signerlist) { ksba_cert_t cert = get_default_signer (ctrl); if (!cert) { log_error ("no default signer found\n"); gpgsm_status2 (ctrl, STATUS_INV_SGNR, get_inv_recpsgnr_code (GPG_ERR_NO_SECKEY), NULL); rc = gpg_error (GPG_ERR_GENERAL); goto leave; } /* Although we don't check for ambiguous specification we will check that the signer's certificate is usable and valid. */ rc = gpgsm_cert_use_sign_p (cert); if (!rc) rc = gpgsm_validate_chain (ctrl, cert, "", NULL, 0, NULL, 0, NULL); if (rc) { char *tmpfpr; tmpfpr = gpgsm_get_fingerprint_hexstring (cert, 0); gpgsm_status2 (ctrl, STATUS_INV_SGNR, get_inv_recpsgnr_code (rc), tmpfpr, NULL); xfree (tmpfpr); goto leave; } /* That one is fine - create signerlist. */ signerlist = xtrycalloc (1, sizeof *signerlist); if (!signerlist) { rc = out_of_core (); ksba_cert_release (cert); goto leave; } signerlist->cert = cert; release_signerlist = 1; } /* Figure out the hash algorithm to use. We do not want to use the one for the certificate but if possible an OID for the plain algorithm. */ if (opt.forced_digest_algo && opt.verbose) log_info ("user requested hash algorithm %d\n", opt.forced_digest_algo); for (i=0, cl=signerlist; cl; cl = cl->next, i++) { const char *oid; if (opt.forced_digest_algo) { oid = NULL; cl->hash_algo = opt.forced_digest_algo; } else { oid = ksba_cert_get_digest_algo (cl->cert); cl->hash_algo = oid ? gcry_md_map_name (oid) : 0; } switch (cl->hash_algo) { case GCRY_MD_SHA1: oid = "1.3.14.3.2.26"; break; case GCRY_MD_RMD160: oid = "1.3.36.3.2.1"; break; case GCRY_MD_SHA224: oid = "2.16.840.1.101.3.4.2.4"; break; case GCRY_MD_SHA256: oid = "2.16.840.1.101.3.4.2.1"; break; case GCRY_MD_SHA384: oid = "2.16.840.1.101.3.4.2.2"; break; case GCRY_MD_SHA512: oid = "2.16.840.1.101.3.4.2.3"; break; /* case GCRY_MD_WHIRLPOOL: oid = "No OID yet"; break; */ case GCRY_MD_MD5: /* We don't want to use MD5. */ case 0: /* No algorithm found in cert. */ default: /* Other algorithms. */ log_info (_("hash algorithm %d (%s) for signer %d not supported;" " using %s\n"), cl->hash_algo, oid? oid: "?", i, gcry_md_algo_name (GCRY_MD_SHA1)); cl->hash_algo = GCRY_MD_SHA1; oid = "1.3.14.3.2.26"; break; } cl->hash_algo_oid = oid; /* Check compliance. */ if (! gnupg_digest_is_allowed (opt.compliance, 1, cl->hash_algo)) { log_error (_("digest algorithm '%s' may not be used in %s mode\n"), gcry_md_algo_name (cl->hash_algo), gnupg_compliance_option_string (opt.compliance)); err = gpg_error (GPG_ERR_DIGEST_ALGO); goto leave; } { unsigned int nbits; int pk_algo = gpgsm_get_key_algo_info (cl->cert, &nbits); if (! gnupg_pk_is_allowed (opt.compliance, PK_USE_SIGNING, pk_algo, NULL, nbits, NULL)) { char kidstr[10+1]; snprintf (kidstr, sizeof kidstr, "0x%08lX", gpgsm_get_short_fingerprint (cl->cert, NULL)); log_error (_("key %s may not be used for signing in %s mode\n"), kidstr, gnupg_compliance_option_string (opt.compliance)); err = gpg_error (GPG_ERR_PUBKEY_ALGO); goto leave; } } } if (opt.verbose) { for (i=0, cl=signerlist; cl; cl = cl->next, i++) log_info (_("hash algorithm used for signer %d: %s (%s)\n"), i, gcry_md_algo_name (cl->hash_algo), cl->hash_algo_oid); } /* 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, cl->hash_algo_oid); 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. */ if (!opt.no_chain_validation) { 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_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:"?"); rc = gpg_error (GPG_ERR_BUG); goto leave; } gcry_md_enable (data_md, algo); audit_log_i (ctrl->audit, AUDIT_DATA_HASH_ALGO, algo); } audit_log (ctrl->audit, AUDIT_SETUP_READY); 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; if (!hash_data (data_fd, data_md)) audit_log (ctrl->audit, AUDIT_GOT_DATA); for (cl=signerlist,signer=0; cl; cl = cl->next, signer++) { digest = gcry_md_read (data_md, cl->hash_algo); digest_len = gcry_md_get_algo_dlen (cl->hash_algo); if ( !digest || !digest_len ) { log_error ("problem getting the hash of the data\n"); rc = gpg_error (GPG_ERR_BUG); goto leave; } 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); rc = hash_and_copy_data (data_fd, data_md, writer); if (rc) goto leave; audit_log (ctrl->audit, AUDIT_GOT_DATA); for (cl=signerlist,signer=0; cl; cl = cl->next, signer++) { digest = gcry_md_read (data_md, cl->hash_algo); digest_len = gcry_md_get_algo_dlen (cl->hash_algo); if ( !digest || !digest_len ) { log_error ("problem getting the hash of the data\n"); rc = gpg_error (GPG_ERR_BUG); goto leave; } 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) { /* Compute the signature for all signers. */ gcry_md_hd_t md; rc = gcry_md_open (&md, 0, 0); if (rc) { log_error ("md_open failed: %s\n", gpg_strerror (rc)); goto leave; } if (DBG_HASHING) gcry_md_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; audit_log_i (ctrl->audit, AUDIT_NEW_SIG, signer); if (signer) gcry_md_reset (md); { certlist_t cl_tmp; for (cl_tmp=signerlist; cl_tmp; cl_tmp = cl_tmp->next) { gcry_md_enable (md, cl_tmp->hash_algo); audit_log_i (ctrl->audit, AUDIT_ATTR_HASH_ALGO, cl_tmp->hash_algo); } } 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, cl->hash_algo, &sigval); if (rc) { audit_log_cert (ctrl->audit, AUDIT_SIGNED_BY, cl->cert, rc); gcry_md_close (md); goto leave; } err = ksba_cms_set_sig_val (cms, signer, sigval); xfree (sigval); if (err) { audit_log_cert (ctrl->audit, AUDIT_SIGNED_BY, cl->cert, 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; } rc = 0; { int pkalgo = gpgsm_get_key_algo_info (cl->cert, NULL); buf = xtryasprintf ("%c %d %d 00 %s %s", detached? 'D':'S', pkalgo, cl->hash_algo, signed_at, fpr); if (!buf) rc = gpg_error_from_syserror (); } xfree (fpr); if (rc) { gcry_md_close (md); goto leave; } gpgsm_status (ctrl, STATUS_SIG_CREATED, buf); xfree (buf); audit_log_cert (ctrl->audit, AUDIT_SIGNED_BY, cl->cert, 0); } gcry_md_close (md); } } while (stopreason != KSBA_SR_READY); rc = gnupg_ksba_finish_writer (b64writer); if (rc) { log_error ("write failed: %s\n", gpg_strerror (rc)); goto leave; } audit_log (ctrl->audit, AUDIT_SIGNING_DONE); 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); gnupg_ksba_destroy_writer (b64writer); keydb_release (kh); gcry_md_close (data_md); return rc; }