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src/crypto/cms.c
1 152 строки
30 KB
Michael Brown
[malloc] Add zfree() to zero and then free a memory block
29 июл 2026, 13:25
29 июл 2026, 13:25
9c70e9b
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/* * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>. * * This program 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 any later version. * * This program 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. * * You can also choose to distribute this program under the terms of * the Unmodified Binary Distribution Licence (as given in the file * COPYING.UBDL), provided that you have satisfied its requirements. */ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL ); FILE_SECBOOT ( PERMITTED ); /** @file * * Cryptographic Message Syntax (PKCS #7) * * The format of CMS messages is defined in RFC 5652. * */ #include <stdint.h> #include <string.h> #include <time.h> #include <errno.h> #include <ipxe/asn1.h> #include <ipxe/x509.h> #include <ipxe/image.h> #include <ipxe/malloc.h> #include <ipxe/privkey.h> #include <ipxe/cms.h> /* Disambiguate the various error causes */ #define EACCES_NON_SIGNING \ __einfo_error ( EINFO_EACCES_NON_SIGNING ) #define EINFO_EACCES_NON_SIGNING \ __einfo_uniqify ( EINFO_EACCES, 0x01, "Not a signing certificate" ) #define EACCES_NON_CODE_SIGNING \ __einfo_error ( EINFO_EACCES_NON_CODE_SIGNING ) #define EINFO_EACCES_NON_CODE_SIGNING \ __einfo_uniqify ( EINFO_EACCES, 0x02, "Not a code-signing certificate" ) #define EACCES_WRONG_NAME \ __einfo_error ( EINFO_EACCES_WRONG_NAME ) #define EINFO_EACCES_WRONG_NAME \ __einfo_uniqify ( EINFO_EACCES, 0x04, "Incorrect certificate name" ) #define EACCES_NO_SIGNATURES \ __einfo_error ( EINFO_EACCES_NO_SIGNATURES ) #define EINFO_EACCES_NO_SIGNATURES \ __einfo_uniqify ( EINFO_EACCES, 0x05, "No signatures present" ) #define EACCES_NO_RECIPIENTS \ __einfo_error ( EINFO_EACCES_NO_RECIPIENTS ) #define EINFO_EACCES_NO_RECIPIENTS \ __einfo_uniqify ( EINFO_EACCES, 0x06, "No usable recipients" ) #define EACCES_LEN \ __einfo_error ( EINFO_EACCES_LEN ) #define EINFO_EACCES_LEN \ __einfo_uniqify ( EINFO_EACCES, 0x07, "Bad file length" ) #define EACCES_PAD \ __einfo_error ( EINFO_EACCES_PAD ) #define EINFO_EACCES_PAD \ __einfo_uniqify ( EINFO_EACCES, 0x08, "Bad block padding" ) #define EACCES_MAC \ __einfo_error ( EINFO_EACCES_MAC ) #define EINFO_EACCES_MAC \ __einfo_uniqify ( EINFO_EACCES, 0x09, "Invalid MAC" ) #define ENOTSUP_TYPE \ __einfo_error ( EINFO_ENOTSUP_TYPE ) #define EINFO_ENOTSUP_TYPE \ __einfo_uniqify ( EINFO_ENOTSUP, 0x01, "Unrecognised message type" ) static int cms_parse_signed ( struct cms_message *cms, const struct asn1_cursor *raw ); static int cms_parse_enveloped ( struct cms_message *cms, const struct asn1_cursor *raw ); /** "id-signedData" object identifier */ static uint8_t oid_signeddata[] = { ASN1_OID_SIGNEDDATA }; /** "id-envelopedData" object identifier */ static uint8_t oid_envelopeddata[] = { ASN1_OID_ENVELOPEDDATA }; /** "id-authEnvelopedData" object identifier */ static uint8_t oid_authenvelopeddata[] = { ASN1_OID_AUTHENVELOPEDDATA }; /** CMS message types */ static struct cms_type cms_types[] = { { .name = "signed", .oid = ASN1_CURSOR ( oid_signeddata ), .parse = cms_parse_signed, }, { .name = "enveloped", .oid = ASN1_CURSOR ( oid_envelopeddata ), .parse = cms_parse_enveloped, }, { .name = "authEnveloped", .oid = ASN1_CURSOR ( oid_authenvelopeddata ), .parse = cms_parse_enveloped, } }; /** * Parse CMS message content type * * @v cms CMS message * @v raw ASN.1 cursor * @ret rc Return status code */ static int cms_parse_content_type ( struct cms_message *cms, const struct asn1_cursor *raw ) { struct asn1_cursor cursor; struct cms_type *type; unsigned int i; /* Enter contentType */ memcpy ( &cursor, raw, sizeof ( cursor ) ); asn1_enter ( &cursor, ASN1_OID ); /* Check for a recognised OID */ for ( i = 0 ; i < ( sizeof ( cms_types ) / sizeof ( cms_types[0] ) ) ; i++ ) { type = &cms_types[i]; if ( asn1_compare ( &cursor, &type->oid ) == 0 ) { cms->type = type; DBGC ( cms, "CMS %p contains %sData\n", cms, type->name ); return 0; } } DBGC ( cms, "CMS %p is not a recognised message type:\n", cms ); DBGC_HDA ( cms, 0, raw->data, raw->len ); return -ENOTSUP_TYPE; } /** * Parse CMS message certificate list * * @v cms CMS message * @v raw ASN.1 cursor * @ret rc Return status code */ static int cms_parse_certificates ( struct cms_message *cms, const struct asn1_cursor *raw ) { struct asn1_cursor cursor; struct x509_certificate *cert; int rc; /* Enter certificates */ memcpy ( &cursor, raw, sizeof ( cursor ) ); asn1_enter ( &cursor, ASN1_EXPLICIT_TAG ( 0 ) ); /* Add each certificate */ while ( cursor.len ) { /* Add certificate to chain */ if ( ( rc = x509_append_raw ( cms->certificates, cursor.data, cursor.len ) ) != 0 ) { DBGC ( cms, "CMS %p could not append certificate: %s\n", cms, strerror ( rc) ); DBGC_HDA ( cms, 0, cursor.data, cursor.len ); return rc; } cert = x509_last ( cms->certificates ); DBGC ( cms, "CMS %p found certificate %s\n", cms, x509_name ( cert ) ); /* Move to next certificate */ asn1_skip_any ( &cursor ); } return 0; } /** * Parse CMS message participant identifier * * @v cms CMS message * @v part Participant information to fill in * @v raw ASN.1 cursor * @ret rc Return status code */ static int cms_parse_identifier ( struct cms_message *cms, struct cms_participant *part, const struct asn1_cursor *raw ) { struct asn1_cursor cursor; struct asn1_cursor serial; struct asn1_cursor issuer; struct x509_certificate *cert; int rc; /* Enter issuerAndSerialNumber */ memcpy ( &cursor, raw, sizeof ( cursor ) ); asn1_enter ( &cursor, ASN1_SEQUENCE ); /* Identify issuer */ memcpy ( &issuer, &cursor, sizeof ( issuer ) ); if ( ( rc = asn1_shrink ( &issuer, ASN1_SEQUENCE ) ) != 0 ) { DBGC ( cms, "CMS %p/%p could not locate issuer: %s\n", cms, part, strerror ( rc ) ); DBGC_HDA ( cms, 0, raw->data, raw->len ); return rc; } DBGC ( cms, "CMS %p/%p issuer is:\n", cms, part ); DBGC_HDA ( cms, 0, issuer.data, issuer.len ); asn1_skip_any ( &cursor ); /* Identify serialNumber */ memcpy ( &serial, &cursor, sizeof ( serial ) ); if ( ( rc = asn1_shrink ( &serial, ASN1_INTEGER ) ) != 0 ) { DBGC ( cms, "CMS %p/%p could not locate serialNumber: %s\n", cms, part, strerror ( rc ) ); DBGC_HDA ( cms, 0, raw->data, raw->len ); return rc; } DBGC ( cms, "CMS %p/%p serial number is:\n", cms, part ); DBGC_HDA ( cms, 0, serial.data, serial.len ); /* Identify certificate */ cert = x509_find_issuer_serial ( cms->certificates, &issuer, &serial ); if ( ! cert ) { DBGC ( cms, "CMS %p/%p could not identify certificate\n", cms, part ); return ( cms_is_signature ( cms ) ? -ENOENT : 0 ); } /* Append certificate to chain */ if ( ( rc = x509_append ( part->chain, cert ) ) != 0 ) { DBGC ( cms, "CMS %p/%p could not append certificate: %s\n", cms, part, strerror ( rc ) ); return rc; } /* Append remaining certificates to chain */ if ( ( rc = x509_auto_append ( part->chain, cms->certificates ) ) != 0 ) { DBGC ( cms, "CMS %p/%p could not append certificates: %s\n", cms, part, strerror ( rc ) ); return rc; } return 0; } /** * Parse CMS message digest algorithm * * @v cms CMS message * @v part Participant information to fill in * @v raw ASN.1 cursor * @ret rc Return status code */ static int cms_parse_digest_algorithm ( struct cms_message *cms, struct cms_participant *part, const struct asn1_cursor *raw ) { struct asn1_algorithm *algorithm; int rc; /* Identify algorithm */ if ( ( rc = asn1_digest_algorithm ( raw, &algorithm ) ) != 0 ) { DBGC ( cms, "CMS %p/%p could not identify digest algorithm: " "%s\n", cms, part, strerror ( rc ) ); DBGC_HDA ( cms, 0, raw->data, raw->len ); return rc; } /* Record digest algorithm */ part->digest = algorithm->digest; DBGC ( cms, "CMS %p/%p digest algorithm is %s\n", cms, part, algorithm->name ); return 0; } /** * Parse CMS message public-key algorithm * * @v cms CMS message * @v part Participant information to fill in * @v raw ASN.1 cursor * @ret rc Return status code */ static int cms_parse_pubkey_algorithm ( struct cms_message *cms, struct cms_participant *part, const struct asn1_cursor *raw ) { struct asn1_algorithm *algorithm; int rc; /* Identify algorithm */ if ( ( rc = asn1_pubkey_algorithm ( raw, &algorithm ) ) != 0 ) { DBGC ( cms, "CMS %p/%p could not identify public-key " "algorithm: %s\n", cms, part, strerror ( rc ) ); DBGC_HDA ( cms, 0, raw->data, raw->len ); return rc; } /* Record public-key algorithm */ part->pubkey = algorithm->pubkey; DBGC ( cms, "CMS %p/%p public-key algorithm is %s\n", cms, part, algorithm->name ); return 0; } /** * Parse CMS message cipher algorithm * * @v cms CMS message * @v raw ASN.1 cursor * @ret rc Return status code */ static int cms_parse_cipher_algorithm ( struct cms_message *cms, const struct asn1_cursor *raw ) { struct asn1_algorithm *algorithm; int rc; /* Identify algorithm */ if ( ( rc = asn1_cipher_algorithm ( raw, &algorithm, &cms->iv ) ) != 0 ) { DBGC ( cms, "CMS %p could not identify cipher algorithm: %s\n", cms, strerror ( rc ) ); DBGC_HDA ( cms, 0, raw->data, raw->len ); return rc; } /* Record cipher */ cms->cipher = algorithm->cipher; DBGC ( cms, "CMS %p cipher algorithm is %s\n", cms, algorithm->name ); return 0; } /** * Parse CMS message signature or key value * * @v cms CMS message * @v part Participant information to fill in * @v raw ASN.1 cursor * @ret rc Return status code */ static int cms_parse_value ( struct cms_message *cms, struct cms_participant *part, const struct asn1_cursor *raw ) { int rc; /* Enter signature or encryptedKey */ memcpy ( &part->value, raw, sizeof ( part->value ) ); if ( ( rc = asn1_enter ( &part->value, ASN1_OCTET_STRING ) ) != 0 ) { DBGC ( cms, "CMS %p/%p could not locate value:\n", cms, part ); DBGC_HDA ( cms, 0, raw->data, raw->len ); return rc; } DBGC ( cms, "CMS %p/%p value is:\n", cms, part ); DBGC_HDA ( cms, 0, part->value.data, part->value.len ); return 0; } /** * Parse CMS message participant information * * @v cms CMS message * @v part Participant information to fill in * @v raw ASN.1 cursor * @ret rc Return status code */ static int cms_parse_participant ( struct cms_message *cms, struct cms_participant *part, const struct asn1_cursor *raw ) { struct asn1_cursor cursor; int rc; /* Enter signerInfo or ktri */ memcpy ( &cursor, raw, sizeof ( cursor ) ); asn1_enter ( &cursor, ASN1_SEQUENCE ); /* Skip version */ asn1_skip ( &cursor, ASN1_INTEGER ); /* Parse sid or rid */ if ( ( rc = cms_parse_identifier ( cms, part, &cursor ) ) != 0 ) return rc; asn1_skip_any ( &cursor ); /* Parse signature-only objects */ if ( cms_is_signature ( cms ) ) { /* Parse digestAlgorithm */ if ( ( rc = cms_parse_digest_algorithm ( cms, part, &cursor ) ) != 0 ) return rc; asn1_skip_any ( &cursor ); /* Skip signedAttrs, if present */ asn1_skip_if_exists ( &cursor, ASN1_EXPLICIT_TAG ( 0 ) ); } /* Parse signatureAlgorithm or contentEncryptionAlgorithm */ if ( ( rc = cms_parse_pubkey_algorithm ( cms, part, &cursor ) ) != 0 ) return rc; asn1_skip_any ( &cursor ); /* Parse signature or encryptedKey */ if ( ( rc = cms_parse_value ( cms, part, &cursor ) ) != 0 ) return rc; return 0; } /** * Parse CMS message participants information * * @v cms CMS message * @v raw ASN.1 cursor * @ret rc Return status code */ static int cms_parse_participants ( struct cms_message *cms, const struct asn1_cursor *raw ) { struct asn1_cursor cursor; struct cms_participant *part; int rc; /* Enter signerInfos or recipientInfos */ memcpy ( &cursor, raw, sizeof ( cursor ) ); asn1_enter ( &cursor, ASN1_SET ); /* Add each signerInfo or recipientInfo. Errors are handled * by ensuring that cms_put() will always be able to free any * allocated memory. */ while ( cursor.len ) { /* Allocate participant information block */ part = zalloc ( sizeof ( *part ) ); if ( ! part ) return -ENOMEM; list_add ( &part->list, &cms->participants ); part->digest = &digest_null; part->pubkey = &pubkey_null; /* Allocate certificate chain */ part->chain = x509_alloc_chain(); if ( ! part->chain ) return -ENOMEM; /* Parse signerInfo or recipientInfo */ if ( ( rc = cms_parse_participant ( cms, part, &cursor ) ) != 0 ) return rc; asn1_skip_any ( &cursor ); } return 0; } /** * Parse CMS message encrypted content information * * @v cms CMS message * @v raw ASN.1 cursor * @ret rc Return status code */ static int cms_parse_encrypted ( struct cms_message *cms, const struct asn1_cursor *raw ) { struct asn1_cursor cursor; int rc; /* Enter encryptedContentInfo */ memcpy ( &cursor, raw, sizeof ( cursor ) ); asn1_enter ( &cursor, ASN1_SEQUENCE ); /* Skip contentType */ asn1_skip ( &cursor, ASN1_OID ); /* Parse contentEncryptionAlgorithm */ if ( ( rc = cms_parse_cipher_algorithm ( cms, &cursor ) ) != 0 ) return rc; return 0; } /** * Parse CMS message MAC * * @v cms CMS message * @v raw ASN.1 cursor * @ret rc Return status code */ static int cms_parse_mac ( struct cms_message *cms, const struct asn1_cursor *raw ) { int rc; /* Enter mac */ memcpy ( &cms->mac, raw, sizeof ( cms->mac ) ); if ( ( rc = asn1_enter ( &cms->mac, ASN1_OCTET_STRING ) ) != 0 ) { DBGC ( cms, "CMS %p could not locate mac: %s\n", cms, strerror ( rc ) ); DBGC_HDA ( cms, 0, raw->data, raw->len ); return rc; } DBGC ( cms, "CMS %p mac is:\n", cms ); DBGC_HDA ( cms, 0, cms->mac.data, cms->mac.len ); return 0; } /** * Parse CMS signed data * * @v cms CMS message * @v raw ASN.1 cursor * @ret rc Return status code */ static int cms_parse_signed ( struct cms_message *cms, const struct asn1_cursor *raw ) { struct asn1_cursor cursor; int rc; /* Allocate certificate list */ cms->certificates = x509_alloc_chain(); if ( ! cms->certificates ) return -ENOMEM; /* Enter signedData */ memcpy ( &cursor, raw, sizeof ( cursor ) ); asn1_enter ( &cursor, ASN1_SEQUENCE ); /* Skip version */ asn1_skip ( &cursor, ASN1_INTEGER ); /* Skip digestAlgorithms */ asn1_skip ( &cursor, ASN1_SET ); /* Skip encapContentInfo */ asn1_skip ( &cursor, ASN1_SEQUENCE ); /* Parse certificates */ if ( ( rc = cms_parse_certificates ( cms, &cursor ) ) != 0 ) return rc; asn1_skip_any ( &cursor ); /* Skip crls, if present */ asn1_skip_if_exists ( &cursor, ASN1_EXPLICIT_TAG ( 1 ) ); /* Parse signerInfos */ if ( ( rc = cms_parse_participants ( cms, &cursor ) ) != 0 ) return rc; return 0; } /** * Parse CMS enveloped data * * @v cms CMS message * @v raw ASN.1 cursor * @ret rc Return status code */ static int cms_parse_enveloped ( struct cms_message *cms, const struct asn1_cursor *raw ) { struct asn1_cursor cursor; int rc; /* Enter envelopedData or authEnvelopedData */ memcpy ( &cursor, raw, sizeof ( cursor ) ); asn1_enter ( &cursor, ASN1_SEQUENCE ); /* Skip version */ asn1_skip ( &cursor, ASN1_INTEGER ); /* Skip originatorInfo, if present */ asn1_skip_if_exists ( &cursor, ASN1_IMPLICIT_TAG ( 0 ) ); /* Parse recipientInfos */ if ( ( rc = cms_parse_participants ( cms, &cursor ) ) != 0 ) return rc; asn1_skip_any ( &cursor ); /* Parse encryptedContentInfo or authEncryptedContentInfo */ if ( ( rc = cms_parse_encrypted ( cms, &cursor ) ) != 0 ) return rc; asn1_skip_any ( &cursor ); assert ( cms->cipher != NULL ); /* Skip unprotectedAttrs or authAttrs, if present */ asn1_skip_if_exists ( &cursor, ASN1_IMPLICIT_TAG ( 1 ) ); /* Parse mac, if present */ if ( ( cms->cipher->authsize != 0 ) && ( ( rc = cms_parse_mac ( cms, &cursor ) ) != 0 ) ) return rc; return 0; } /** * Parse CMS message from ASN.1 data * * @v cms CMS message * @ret rc Return status code */ static int cms_parse ( struct cms_message *cms ) { struct asn1_cursor cursor; int rc; /* Enter contentInfo */ memcpy ( &cursor, cms->raw, sizeof ( cursor ) ); asn1_enter ( &cursor, ASN1_SEQUENCE ); /* Parse contentType */ if ( ( rc = cms_parse_content_type ( cms, &cursor ) ) != 0 ) return rc; asn1_skip_any ( &cursor ); /* Enter content */ asn1_enter ( &cursor, ASN1_EXPLICIT_TAG ( 0 ) ); /* Parse type-specific content */ if ( ( rc = cms->type->parse ( cms, &cursor ) ) != 0 ) return rc; return 0; } /** * Free CMS message * * @v refcnt Reference count */ static void cms_free ( struct refcnt *refcnt ) { struct cms_message *cms = container_of ( refcnt, struct cms_message, refcnt ); struct cms_participant *part; struct cms_participant *tmp; list_for_each_entry_safe ( part, tmp, &cms->participants, list ) { list_del ( &part->list ); x509_chain_put ( part->chain ); free ( part ); } x509_chain_put ( cms->certificates ); free ( cms->raw ); free ( cms ); } /** * Create CMS message * * @v image Image * @ret sig CMS message * @ret rc Return status code * * On success, the caller holds a reference to the CMS message, and * is responsible for ultimately calling cms_put(). */ int cms_message ( struct image *image, struct cms_message **cms ) { int next; int rc; /* Allocate and initialise message */ *cms = zalloc ( sizeof ( **cms ) ); if ( ! *cms ) { rc = -ENOMEM; goto err_alloc; } ref_init ( &(*cms)->refcnt, cms_free ); INIT_LIST_HEAD ( &(*cms)->participants ); (*cms)->cipher = &cipher_null; /* Get raw message data */ next = image_asn1 ( image, 0, &(*cms)->raw ); if ( next < 0 ) { rc = next; DBGC ( *cms, "CMS %p could not get raw ASN.1 data: %s\n", *cms, strerror ( rc ) ); goto err_asn1; } /* Use only first message in image */ asn1_shrink_any ( (*cms)->raw ); /* Parse message */ if ( ( rc = cms_parse ( *cms ) ) != 0 ) goto err_parse; return 0; err_parse: err_asn1: cms_put ( *cms ); err_alloc: return rc; } /** * Calculate digest of CMS-signed data * * @v cms CMS message * @v part Participant information * @v data Signed data * @v len Length of signed data * @v out Digest output */ static void cms_digest ( struct cms_message *cms, struct cms_participant *part, const void *data, size_t len, void *out ) { struct digest_algorithm *digest = part->digest; uint8_t ctx[ digest->ctxsize ]; /* Calculate digest */ digest_init ( digest, ctx ); digest_update ( digest, ctx, data, len ); digest_final ( digest, ctx, out ); DBGC ( cms, "CMS %p/%p digest value:\n", cms, part ); DBGC_HDA ( cms, 0, out, digest->digestsize ); } /** * Verify digest of CMS-signed data * * @v cms CMS message * @v part Participant information * @v cert Corresponding certificate * @v data Signed data * @v len Length of signed data * @ret rc Return status code */ static int cms_verify_digest ( struct cms_message *cms, struct cms_participant *part, struct x509_certificate *cert, const void *data, size_t len ) { struct digest_algorithm *digest = part->digest; struct pubkey_algorithm *pubkey = part->pubkey; const struct asn1_cursor *key = &cert->subject.public_key.raw; const struct asn1_cursor *value = &part->value; uint8_t digest_out[ digest->digestsize ]; int rc; /* Generate digest */ cms_digest ( cms, part, data, len, digest_out ); /* Verify digest */ if ( ( rc = pubkey_verify ( pubkey, key, digest, digest_out, value ) ) != 0 ) { DBGC ( cms, "CMS %p/%p signature verification failed: %s\n", cms, part, strerror ( rc ) ); return rc; } return 0; } /** * Verify CMS message signer * * @v cms CMS message * @v part Participant information * @v data Signed data * @v len Length of signed data * @v time Time at which to validate certificates * @v store Certificate store, or NULL to use default * @v root Root certificate list, or NULL to use default * @ret rc Return status code */ static int cms_verify_signer ( struct cms_message *cms, struct cms_participant *part, const void *data, size_t len, time_t time, struct x509_chain *store, struct x509_root *root ) { struct x509_certificate *cert; int rc; /* Validate certificate chain */ if ( ( rc = x509_validate_chain ( part->chain, time, store, root ) ) != 0 ) { DBGC ( cms, "CMS %p/%p could not validate chain: %s\n", cms, part, strerror ( rc ) ); return rc; } /* Extract code-signing certificate */ cert = x509_first ( part->chain ); assert ( cert != NULL ); /* Check that certificate can create digital signatures */ if ( ! ( cert->extensions.usage.bits & X509_DIGITAL_SIGNATURE ) ) { DBGC ( cms, "CMS %p/%p certificate cannot create signatures\n", cms, part ); return -EACCES_NON_SIGNING; } /* Check that certificate can sign code */ if ( ! ( cert->extensions.ext_usage.bits & X509_CODE_SIGNING ) ) { DBGC ( cms, "CMS %p/%p certificate is not code-signing\n", cms, part ); return -EACCES_NON_CODE_SIGNING; } /* Verify digest */ if ( ( rc = cms_verify_digest ( cms, part, cert, data, len ) ) != 0 ) return rc; return 0; } /** * Verify CMS signature * * @v cms CMS message * @v image Signed image * @v name Required common name, or NULL to check all signatures * @v time Time at which to validate certificates * @v store Certificate store, or NULL to use default * @v root Root certificate list, or NULL to use default * @ret rc Return status code */ int cms_verify ( struct cms_message *cms, struct image *image, const char *name, time_t time, struct x509_chain *store, struct x509_root *root ) { struct cms_participant *part; struct x509_certificate *cert; int count = 0; int rc; /* Mark image as untrusted */ image_untrust ( image ); /* Sanity check */ if ( ! cms_is_signature ( cms ) ) return -ENOTTY; /* Verify using all signers */ list_for_each_entry ( part, &cms->participants, list ) { cert = x509_first ( part->chain ); if ( name && ( x509_check_name ( cert, name ) != 0 ) ) continue; if ( ( rc = cms_verify_signer ( cms, part, image->data, image->len, time, store, root ) ) != 0 ) return rc; count++; } /* Check that we have verified at least one signature */ if ( count == 0 ) { if ( name ) { DBGC ( cms, "CMS %p had no signatures matching name " "%s\n", cms, name ); return -EACCES_WRONG_NAME; } else { DBGC ( cms, "CMS %p had no signatures\n", cms ); return -EACCES_NO_SIGNATURES; } } /* Mark image as trusted */ image_trust ( image ); return 0; } /** * Identify CMS recipient corresponding to private key * * @v cms CMS message * @v private_key Private key * @ret part Participant information, or NULL if not found */ static struct cms_participant * cms_recipient ( struct cms_message *cms, struct private_key *private_key ) { struct cms_participant *part; struct x509_certificate *cert; /* Identify certificate (if any) for which we have a private key */ cert = x509_find_key ( NULL, private_key ); if ( ! cert ) return NULL; /* Identify corresponding recipient, if any */ list_for_each_entry ( part, &cms->participants, list ) { if ( cert == x509_first ( part->chain ) ) return part; } return NULL; } /** * Set CMS cipher key * * @v cms CMS message * @v part Participant information * @v private_key Private key * @v ctx Cipher context * @ret rc Return status code */ static int cms_cipher_key ( struct cms_message *cms, struct cms_participant *part, struct private_key *private_key, void *ctx ) { struct cipher_algorithm *cipher = cms->cipher; struct pubkey_algorithm *pubkey = part->pubkey; const struct asn1_cursor *key = privkey_cursor ( private_key ); const struct asn1_cursor *value = &part->value; struct asn1_builder cipher_key = { NULL, 0 }; int rc; /* Decrypt cipher key */ if ( ( rc = pubkey_decrypt ( pubkey, key, value, &cipher_key ) ) != 0 ) { DBGC ( cms, "CMS %p/%p could not decrypt cipher key: %s\n", cms, part, strerror ( rc ) ); DBGC_HDA ( cms, 0, value->data, value->len ); goto err_decrypt; } DBGC ( cms, "CMS %p/%p cipher key:\n", cms, part ); DBGC_HDA ( cms, 0, cipher_key.data, cipher_key.len ); /* Set cipher key */ if ( ( rc = cipher_setkey ( cipher, ctx, cipher_key.data, cipher_key.len ) ) != 0 ) { DBGC ( cms, "CMS %p could not set cipher key: %s\n", cms, strerror ( rc ) ); goto err_setkey; } /* Set cipher initialization vector */ if ( ( rc = cipher_setiv ( cipher, ctx, cms->iv.data, cms->iv.len ) ) != 0 ) { DBGC ( cms, "CMS %p could not set cipher IV: %s\n", cms, strerror ( rc ) ); goto err_setiv; } if ( cms->iv.len ) { DBGC ( cms, "CMS %p cipher IV:\n", cms ); DBGC_HDA ( cms, 0, cms->iv.data, cms->iv.len ); } err_setiv: err_setkey: err_decrypt: zfree ( cipher_key.data ); return rc; } /** * Initialise cipher for CMS decryption * * @v cms CMS message * @v private_key Private key * @v ctx Cipher context * @ret rc Return status code */ static int cms_cipher ( struct cms_message *cms, struct private_key *private_key, void *ctx ) { struct cms_participant *part; int rc; /* Identify a usable recipient */ part = cms_recipient ( cms, private_key ); if ( ! part ) { DBGC ( cms, "CMS %p had no usable recipients\n", cms ); return -EACCES_NO_RECIPIENTS; } /* Decrypt and set cipher key */ if ( ( rc = cms_cipher_key ( cms, part, private_key, ctx ) ) != 0 ) return rc; return 0; } /** * Check CMS padding * * @v cms CMS message * @v data Final block * @v len Final block length * @ret len Padding length, or negative error */ static int cms_verify_padding ( struct cms_message *cms, const void *data, size_t len ) { struct cipher_algorithm *cipher = cms->cipher; const uint8_t *pad; size_t pad_len; unsigned int i; /* Non-block ciphers do not use padding */ if ( ! is_block_cipher ( cipher ) ) return 0; /* Block padding can never produce an empty file */ if ( len == 0 ) { DBGC ( cms, "CMS %p invalid empty padding\n", cms ); return -EACCES_PAD; } /* Sanity check */ assert ( len >= cipher->blocksize ); /* Extract and verify padding */ pad = ( data + len - 1 ); pad_len = *pad; if ( ( pad_len == 0 ) || ( pad_len > len ) ) { DBGC ( cms, "CMS %p invalid padding length %zd\n", cms, pad_len ); return -EACCES_PAD; } for ( i = 0 ; i < pad_len ; i++ ) { if ( *(pad--) != pad_len ) { DBGC ( cms, "CMS %p invalid padding\n", cms ); DBGC_HDA ( cms, 0, ( data + len - pad_len ), pad_len ); return -EACCES_PAD; } } return pad_len; } /** * Decrypt CMS message * * @v cms CMS message * @v image Image to decrypt * @v name Decrypted image name, or NULL to use default * @v private_key Private key * @ret rc Return status code */ int cms_decrypt ( struct cms_message *cms, struct image *image, const char *name, struct private_key *private_key ) { struct cipher_algorithm *cipher = cms->cipher; const unsigned int original_flags = image->flags; uint8_t ctx[ cipher->ctxsize ]; uint8_t ctxdup[ cipher->ctxsize ]; uint8_t auth[ cipher->authsize ]; uint8_t final[ cipher->blocksize ]; size_t final_len; size_t bulk_len; int pad_len; int rc; /* Check block size */ if ( ( image->len & ( cipher->blocksize - 1 ) ) != 0 ) { DBGC ( cms, "CMS %p invalid length %zd\n", cms, image->len ); rc = -EACCES_LEN; goto err_blocksize; } /* Initialise cipher */ if ( ( rc = cms_cipher ( cms, private_key, ctx ) ) != 0 ) goto err_cipher; /* Duplicate cipher context for potential reencryption on error */ memcpy ( ctxdup, ctx, cipher->ctxsize ); /* Clear trusted flag before modifying image */ image_untrust ( image ); /* Temporarily unregister image, if applicable */ if ( original_flags & IMAGE_REGISTERED ) { image_get ( image ); unregister_image ( image ); } /* Decrypt all but the final block */ final_len = ( ( image->len && is_block_cipher ( cipher ) ) ? cipher->blocksize : 0 ); bulk_len = ( image->len - final_len ); cipher_decrypt ( cipher, ctx, image->data, image->rwdata, bulk_len ); /* Decrypt final block */ cipher_decrypt ( cipher, ctx, ( image->data + bulk_len ), final, final_len ); /* Check authentication tag, if applicable */ cipher_auth ( cipher, ctx, auth ); if ( ( cms->mac.len != cipher->authsize ) || ( memcmp ( cms->mac.data, auth, cipher->authsize ) != 0 ) ) { DBGC ( cms, "CMS %p invalid authentication tag\n", cms ); DBGC_HDA ( cms, 0, auth, cipher->authsize ); rc = -EACCES_MAC; goto err_auth; } /* Check block padding, if applicable */ if ( ( pad_len = cms_verify_padding ( cms, final, final_len ) ) < 0 ) { rc = pad_len; goto err_pad; } /* Update image name. Do this as the last possible failure, so * that we do not have to include any error-handling code path * to restore the original image name (which may itself fail). */ if ( name ) { if ( ( rc = image_set_name ( image, name ) ) != 0 ) goto err_set_name; } else { image_strip_suffix ( image ); } /* Overwrite final fragment and strip block padding. Do this * only once no further failure paths exist, so that we do not * have to include include any error-handling code path to * reconstruct the block padding. */ memcpy ( ( image->rwdata + bulk_len ), final, final_len ); image->len -= pad_len; /* Clear image type and re-register image, if applicable */ image->type = NULL; if ( original_flags & IMAGE_REGISTERED ) { register_image ( image ); image_put ( image ); } return 0; err_set_name: err_pad: err_auth: /* Reencrypt all overwritten portions. This can be done since * we have deliberately not overwritten the final block * containing the potentially invalid (and therefore * unreproducible) block padding. */ cipher_encrypt ( cipher, ctxdup, image->data, image->rwdata, bulk_len ); if ( original_flags & IMAGE_REGISTERED ) { register_image ( image ); /* Cannot fail on re-registration */ image_put ( image ); } image->flags = original_flags; err_cipher: err_blocksize: return rc; }