X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/939c3e349db9662100c7cafa8bc1298dfd8d3798..2592e6c0eda522da0f6a33f4d32e33598288eb6e:/src/src/pdkim/rsa.c diff --git a/src/src/pdkim/rsa.c b/src/src/pdkim/rsa.c new file mode 100644 index 000000000..c5d4c2efa --- /dev/null +++ b/src/src/pdkim/rsa.c @@ -0,0 +1,679 @@ +/* + * PDKIM - a RFC4871 (DKIM) implementation + * + * Copyright (C) 2016 Exim maintainers + * + * RSA signing/verification interface + */ + +#include "../exim.h" + +#ifndef DISABLE_DKIM /* entire file */ + +#ifndef SUPPORT_TLS +# error Need SUPPORT_TLS for DKIM +#endif + +#include "crypt_ver.h" +#include "rsa.h" + + +/******************************************************************************/ +#ifdef RSA_GNUTLS + +void +exim_rsa_init(void) +{ +} + + +/* accumulate data (gnutls-only). String to be appended must be nul-terminated. */ +blob * +exim_rsa_data_append(blob * b, int * alloc, uschar * s) +{ +int len = b->len; +b->data = string_append(b->data, alloc, &len, 1, s); +b->len = len; +return b; +} + + + +/* import private key from PEM string in memory. +Return: NULL for success, or an error string */ + +const uschar * +exim_rsa_signing_init(uschar * privkey_pem, es_ctx * sign_ctx) +{ +gnutls_datum_t k; +int rc; + +k.data = privkey_pem; +k.size = strlen(privkey_pem); + +if ( (rc = gnutls_x509_privkey_init(&sign_ctx->rsa)) != GNUTLS_E_SUCCESS + /*|| (rc = gnutls_x509_privkey_import(sign_ctx->rsa, &k, + GNUTLS_X509_FMT_PEM)) != GNUTLS_E_SUCCESS */ + ) + return gnutls_strerror(rc); + +if ( /* (rc = gnutls_x509_privkey_init(&sign_ctx->rsa)) != GNUTLS_E_SUCCESS + ||*/ (rc = gnutls_x509_privkey_import(sign_ctx->rsa, &k, + GNUTLS_X509_FMT_PEM)) != GNUTLS_E_SUCCESS + ) + return gnutls_strerror(rc); + +return NULL; +} + + + +/* allocate mem for signature (when signing) */ +/* sign data (gnutls_only) +OR +sign hash. + +Return: NULL for success, or an error string */ + +const uschar * +exim_rsa_sign(es_ctx * sign_ctx, BOOL is_sha1, blob * data, blob * sig) +{ +gnutls_datum_t k; +size_t sigsize = 0; +int rc; +const uschar * ret = NULL; + +/* Allocate mem for signature */ +k.data = data->data; +k.size = data->len; +(void) gnutls_x509_privkey_sign_data(sign_ctx->rsa, + is_sha1 ? GNUTLS_DIG_SHA1 : GNUTLS_DIG_SHA256, + 0, &k, NULL, &sigsize); + +sig->data = store_get(sigsize); +sig->len = sigsize; + +/* Do signing */ +if ((rc = gnutls_x509_privkey_sign_data(sign_ctx->rsa, + is_sha1 ? GNUTLS_DIG_SHA1 : GNUTLS_DIG_SHA256, + 0, &k, sig->data, &sigsize)) != GNUTLS_E_SUCCESS + ) + ret = gnutls_strerror(rc); + +gnutls_x509_privkey_deinit(sign_ctx->rsa); +return ret; +} + + + +/* import public key (from DER in memory) +Return: NULL for success, or an error string */ + +const uschar * +exim_rsa_verify_init(blob * pubkey_der, ev_ctx * verify_ctx) +{ +gnutls_datum_t k; +int rc; +const uschar * ret = NULL; + +gnutls_pubkey_init(&verify_ctx->rsa); + +k.data = pubkey_der->data; +k.size = pubkey_der->len; + +if ((rc = gnutls_pubkey_import(verify_ctx->rsa, &k, GNUTLS_X509_FMT_DER)) + != GNUTLS_E_SUCCESS) + ret = gnutls_strerror(rc); +return ret; +} + + +/* verify signature (of hash) (given pubkey & alleged sig) +Return: NULL for success, or an error string */ + +const uschar * +exim_rsa_verify(ev_ctx * verify_ctx, BOOL is_sha1, blob * data_hash, blob * sig) +{ +gnutls_datum_t k, s; +int rc; +const uschar * ret = NULL; + +k.data = data_hash->data; +k.size = data_hash->len; +s.data = sig->data; +s.size = sig->len; +if ((rc = gnutls_pubkey_verify_hash2(verify_ctx->rsa, + is_sha1 ? GNUTLS_SIGN_RSA_SHA1 : GNUTLS_SIGN_RSA_SHA256, + 0, &k, &s)) < 0) + ret = gnutls_strerror(rc); + +gnutls_pubkey_deinit(verify_ctx->rsa); +return ret; +} + + + + +#elif defined(RSA_GCRYPT) +/******************************************************************************/ + + +/* Internal service routine: +Read and move past an asn.1 header, checking class & tag, +optionally returning the data-length */ + +static int +as_tag(blob * der, uschar req_cls, long req_tag, long * alen) +{ +int rc; +uschar tag_class; +int taglen; +long tag, len; + +/* debug_printf("as_tag: %02x %02x %02x %02x\n", + der->data[0], der->data[1], der->data[2], der->data[3]); */ + +if ((rc = asn1_get_tag_der(der->data++, der->len--, &tag_class, &taglen, &tag)) + != ASN1_SUCCESS) + return rc; + +if (tag_class != req_cls || tag != req_tag) return ASN1_ELEMENT_NOT_FOUND; + +if ((len = asn1_get_length_der(der->data, der->len, &taglen)) < 0) + return ASN1_DER_ERROR; +if (alen) *alen = len; + +/* debug_printf("as_tag: tlen %d dlen %d\n", taglen, (int)len); */ + +der->data += taglen; +der->len -= taglen; +return rc; +} + +/* Internal service routine: +Read and move over an asn.1 integer, setting an MPI to the value +*/ + +static uschar * +as_mpi(blob * der, gcry_mpi_t * mpi) +{ +long alen; +int rc; +gcry_error_t gerr; + +/* integer; move past the header */ +if ((rc = as_tag(der, 0, ASN1_TAG_INTEGER, &alen)) != ASN1_SUCCESS) + return US asn1_strerror(rc); + +/* read to an MPI */ +if ((gerr = gcry_mpi_scan(mpi, GCRYMPI_FMT_STD, der->data, alen, NULL))) + return US gcry_strerror(gerr); + +/* move over the data */ +der->data += alen; der->len -= alen; +return NULL; +} + + + +void +exim_rsa_init(void) +{ +/* Version check should be the very first call because it +makes sure that important subsystems are initialized. */ +if (!gcry_check_version (GCRYPT_VERSION)) + { + fputs ("libgcrypt version mismatch\n", stderr); + exit (2); + } + +/* We don't want to see any warnings, e.g. because we have not yet +parsed program options which might be used to suppress such +warnings. */ +gcry_control (GCRYCTL_SUSPEND_SECMEM_WARN); + +/* ... If required, other initialization goes here. Note that the +process might still be running with increased privileges and that +the secure memory has not been initialized. */ + +/* Allocate a pool of 16k secure memory. This make the secure memory +available and also drops privileges where needed. */ +gcry_control (GCRYCTL_INIT_SECMEM, 16384, 0); + +/* It is now okay to let Libgcrypt complain when there was/is +a problem with the secure memory. */ +gcry_control (GCRYCTL_RESUME_SECMEM_WARN); + +/* ... If required, other initialization goes here. */ + +/* Tell Libgcrypt that initialization has completed. */ +gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0); + +return; +} + + + + +/* Accumulate data (gnutls-only). +String to be appended must be nul-terminated. */ + +blob * +exim_rsa_data_append(blob * b, int * alloc, uschar * s) +{ +return b; /*dummy*/ +} + + + +/* import private key from PEM string in memory. +Return: NULL for success, or an error string */ + +const uschar * +exim_rsa_signing_init(uschar * privkey_pem, es_ctx * sign_ctx) +{ +uschar * s1, * s2; +blob der; +long alen; +int rc; + +/* + * RSAPrivateKey ::= SEQUENCE + * version Version, + * modulus INTEGER, -- n + * publicExponent INTEGER, -- e + * privateExponent INTEGER, -- d + * prime1 INTEGER, -- p + * prime2 INTEGER, -- q + * exponent1 INTEGER, -- d mod (p-1) + * exponent2 INTEGER, -- d mod (q-1) + * coefficient INTEGER, -- (inverse of q) mod p + * otherPrimeInfos OtherPrimeInfos OPTIONAL + */ + +if ( !(s1 = Ustrstr(CS privkey_pem, "-----BEGIN RSA PRIVATE KEY-----")) + || !(s2 = Ustrstr(CS (s1+=31), "-----END RSA PRIVATE KEY-----" )) + ) + return US"Bad PEM wrapper"; + +*s2 = '\0'; + +if ((der.len = b64decode(s1, &der.data)) < 0) + return US"Bad PEM-DER b64 decode"; + +/* untangle asn.1 */ + +/* sequence; just move past the header */ +if ((rc = as_tag(&der, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL)) + != ASN1_SUCCESS) goto asn_err; + +/* integer version; move past the header, check is zero */ +if ((rc = as_tag(&der, 0, ASN1_TAG_INTEGER, &alen)) != ASN1_SUCCESS) + goto asn_err; +if (alen != 1 || *der.data != 0) + return US"Bad version number"; +der.data++; der.len--; + +if ( (s1 = as_mpi(&der, &sign_ctx->n)) + || (s1 = as_mpi(&der, &sign_ctx->e)) + || (s1 = as_mpi(&der, &sign_ctx->d)) + || (s1 = as_mpi(&der, &sign_ctx->p)) + || (s1 = as_mpi(&der, &sign_ctx->q)) + || (s1 = as_mpi(&der, &sign_ctx->dp)) + || (s1 = as_mpi(&der, &sign_ctx->dq)) + || (s1 = as_mpi(&der, &sign_ctx->qp)) + ) + return s1; + +DEBUG(D_acl) debug_printf("rsa_signing_init:\n"); + { + uschar * s; + gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->n); + debug_printf(" N : %s\n", s); + gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->e); + debug_printf(" E : %s\n", s); + gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->d); + debug_printf(" D : %s\n", s); + gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->p); + debug_printf(" P : %s\n", s); + gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->q); + debug_printf(" Q : %s\n", s); + gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->dp); + debug_printf(" DP: %s\n", s); + gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->dq); + debug_printf(" DQ: %s\n", s); + gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->qp); + debug_printf(" QP: %s\n", s); + } +return NULL; + +asn_err: return US asn1_strerror(rc); +} + + + +/* allocate mem for signature (when signing) */ +/* sign data (gnutls_only) +OR +sign hash. + +Return: NULL for success, or an error string */ + +const uschar * +exim_rsa_sign(es_ctx * sign_ctx, BOOL is_sha1, blob * data, blob * sig) +{ +gcry_sexp_t s_hash = NULL, s_key = NULL, s_sig = NULL; +gcry_mpi_t m_sig; +uschar * errstr; +gcry_error_t gerr; + +#define SIGSPACE 128 +sig->data = store_get(SIGSPACE); + +if (gcry_mpi_cmp (sign_ctx->p, sign_ctx->q) > 0) + { + gcry_mpi_swap (sign_ctx->p, sign_ctx->q); + gcry_mpi_invm (sign_ctx->qp, sign_ctx->p, sign_ctx->q); + } + +if ( (gerr = gcry_sexp_build (&s_key, NULL, + "(private-key (rsa (n%m)(e%m)(d%m)(p%m)(q%m)(u%m)))", + sign_ctx->n, sign_ctx->e, + sign_ctx->d, sign_ctx->p, + sign_ctx->q, sign_ctx->qp)) + || (gerr = gcry_sexp_build (&s_hash, NULL, + is_sha1 + ? "(data(flags pkcs1)(hash sha1 %b))" + : "(data(flags pkcs1)(hash sha256 %b))", + (int) data->len, CS data->data)) + || (gerr = gcry_pk_sign (&s_sig, s_hash, s_key)) + ) + return US gcry_strerror(gerr); + +/* gcry_sexp_dump(s_sig); */ + +if ( !(s_sig = gcry_sexp_find_token(s_sig, "s", 0)) + ) + return US"no sig result"; + +m_sig = gcry_sexp_nth_mpi(s_sig, 1, GCRYMPI_FMT_USG); + +DEBUG(D_acl) + { + uschar * s; + gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, m_sig); + debug_printf(" SG: %s\n", s); + } + +gerr = gcry_mpi_print(GCRYMPI_FMT_USG, sig->data, SIGSPACE, &sig->len, m_sig); +if (gerr) + { + debug_printf("signature conversion from MPI to buffer failed\n"); + return US gcry_strerror(gerr); + } +#undef SIGSPACE + +return NULL; +} + + +/* import public key (from DER in memory) +Return: NULL for success, or an error string */ + +const uschar * +exim_rsa_verify_init(blob * pubkey_der, ev_ctx * verify_ctx) +{ +/* +in code sequence per b81207d2bfa92 rsa_parse_public_key() and asn1_get_mpi() +*/ +uschar tag_class; +int taglen; +long alen; +int rc; +uschar * errstr; +gcry_error_t gerr; +uschar * stage = US"S1"; + +/* +sequence + sequence + OBJECT:rsaEncryption + NULL + BIT STRING:RSAPublicKey + sequence + INTEGER:Public modulus + INTEGER:Public exponent + +openssl rsa -in aux-fixed/dkim/dkim.private -pubout -outform DER | od -t x1 | head; +openssl rsa -in aux-fixed/dkim/dkim.private -pubout | openssl asn1parse -dump; +openssl rsa -in aux-fixed/dkim/dkim.private -pubout | openssl asn1parse -dump -offset 22; +*/ + +/* sequence; just move past the header */ +if ((rc = as_tag(pubkey_der, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL)) + != ASN1_SUCCESS) goto asn_err; + +/* sequence; skip the entire thing */ +DEBUG(D_acl) stage = US"S2"; +if ((rc = as_tag(pubkey_der, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, &alen)) + != ASN1_SUCCESS) goto asn_err; +pubkey_der->data += alen; pubkey_der->len -= alen; + + +/* bitstring: limit range to size of bitstring; +move over header + content wrapper */ +DEBUG(D_acl) stage = US"BS"; +if ((rc = as_tag(pubkey_der, 0, ASN1_TAG_BIT_STRING, &alen)) != ASN1_SUCCESS) + goto asn_err; +pubkey_der->len = alen; +pubkey_der->data++; pubkey_der->len--; + +/* sequence; just move past the header */ +DEBUG(D_acl) stage = US"S3"; +if ((rc = as_tag(pubkey_der, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL)) + != ASN1_SUCCESS) goto asn_err; + +/* read two integers */ +DEBUG(D_acl) stage = US"MPI"; +if ( (errstr = as_mpi(pubkey_der, &verify_ctx->n)) + || (errstr = as_mpi(pubkey_der, &verify_ctx->e)) + ) + return errstr; + +DEBUG(D_acl) debug_printf("rsa_verify_init:\n"); + { + uschar * s; + gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, verify_ctx->n); + debug_printf(" N : %s\n", s); + gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, verify_ctx->e); + debug_printf(" E : %s\n", s); + } + +return NULL; + +asn_err: +DEBUG(D_acl) return string_sprintf("%s: %s", stage, asn1_strerror(rc)); + return US asn1_strerror(rc); +} + + +/* verify signature (of hash) (given pubkey & alleged sig) +Return: NULL for success, or an error string */ + +const uschar * +exim_rsa_verify(ev_ctx * verify_ctx, BOOL is_sha1, blob * data_hash, blob * sig) +{ +/* +cf. libgnutls 2.8.5 _wrap_gcry_pk_verify() +*/ +gcry_mpi_t m_sig; +gcry_sexp_t s_sig = NULL, s_hash = NULL, s_pkey = NULL; +gcry_error_t gerr; +uschar * stage; + +if ( (stage = US"pkey sexp build", + gerr = gcry_sexp_build (&s_pkey, NULL, "(public-key(rsa(n%m)(e%m)))", + verify_ctx->n, verify_ctx->e)) + || (stage = US"data sexp build", + gerr = gcry_sexp_build (&s_hash, NULL, + is_sha1 + ? "(data(flags pkcs1)(hash sha1 %b))" + : "(data(flags pkcs1)(hash sha256 %b))", + (int) data_hash->len, CS data_hash->data)) + || (stage = US"sig mpi scan", + gerr = gcry_mpi_scan(&m_sig, GCRYMPI_FMT_USG, sig->data, sig->len, NULL)) + || (stage = US"sig sexp build", + gerr = gcry_sexp_build (&s_sig, NULL, "(sig-val(rsa(s%m)))", m_sig)) + || (stage = US"verify", + gerr = gcry_pk_verify (s_sig, s_hash, s_pkey)) + ) + { + DEBUG(D_acl) debug_printf("verify: error in stage '%s'\n", stage); + return US gcry_strerror(gerr); + } + +if (s_sig) gcry_sexp_release (s_sig); +if (s_hash) gcry_sexp_release (s_hash); +if (s_pkey) gcry_sexp_release (s_pkey); +gcry_mpi_release (m_sig); +gcry_mpi_release (verify_ctx->n); +gcry_mpi_release (verify_ctx->e); + +return NULL; +} + + + + +#elif defined(RSA_OPENSSL) +/******************************************************************************/ + +void +exim_rsa_init(void) +{ +} + + +/* accumulate data (gnutls-only) */ +blob * +exim_rsa_data_append(blob * b, int * alloc, uschar * s) +{ +return b; /*dummy*/ +} + + +/* import private key from PEM string in memory. +Return: NULL for success, or an error string */ + +const uschar * +exim_rsa_signing_init(uschar * privkey_pem, es_ctx * sign_ctx) +{ +uschar * p, * q; +int len; + +/* Convert PEM to DER */ +if ( !(p = Ustrstr(privkey_pem, "-----BEGIN RSA PRIVATE KEY-----")) + || !(q = Ustrstr(p+=31, "-----END RSA PRIVATE KEY-----")) + ) + return US"Bad PEM wrapping"; + +*q = '\0'; +if ((len = b64decode(p, &p)) < 0) + return US"b64decode failed"; + +if (!(sign_ctx->rsa = d2i_RSAPrivateKey(NULL, CUSS &p, len))) + { + char ssl_errstring[256]; + ERR_load_crypto_strings(); /*XXX move to a startup routine */ + ERR_error_string(ERR_get_error(), ssl_errstring); + return string_copy(ssl_errstring); + } + +return NULL; +} + + + +/* allocate mem for signature (when signing) */ +/* sign data (gnutls_only) +OR +sign hash. + +Return: NULL for success, or an error string */ + +const uschar * +exim_rsa_sign(es_ctx * sign_ctx, BOOL is_sha1, blob * data, blob * sig) +{ +uint len; +const uschar * ret = NULL; + +/* Allocate mem for signature */ +len = RSA_size(sign_ctx->rsa); +sig->data = store_get(len); +sig->len = len; + +/* Do signing */ +if (RSA_sign(is_sha1 ? NID_sha1 : NID_sha256, + CUS data->data, data->len, + US sig->data, &len, sign_ctx->rsa) != 1) + { + char ssl_errstring[256]; + ERR_load_crypto_strings(); /*XXX move to a startup routine */ + ERR_error_string(ERR_get_error(), ssl_errstring); + ret = string_copy(ssl_errstring); + } + +RSA_free(sign_ctx->rsa); +return ret;; +} + + + +/* import public key (from DER in memory) +Return: nULL for success, or an error string */ + +const uschar * +exim_rsa_verify_init(blob * pubkey_der, ev_ctx * verify_ctx) +{ +const uschar * p = CUS pubkey_der->data; +const uschar * ret = NULL; + +if (!(verify_ctx->rsa = d2i_RSA_PUBKEY(NULL, &p, (long) pubkey_der->len))) + { + char ssl_errstring[256]; + ERR_load_crypto_strings(); /*XXX move to a startup routine */ + ERR_error_string(ERR_get_error(), ssl_errstring); + ret = string_copy(ssl_errstring); + } +return ret; +} + + + + +/* verify signature (of hash) (given pubkey & alleged sig) +Return: NULL for success, or an error string */ + +const uschar * +exim_rsa_verify(ev_ctx * verify_ctx, BOOL is_sha1, blob * data_hash, blob * sig) +{ +const uschar * ret = NULL; + +if (RSA_verify(is_sha1 ? NID_sha1 : NID_sha256, + CUS data_hash->data, data_hash->len, + US sig->data, (uint) sig->len, verify_ctx->rsa) != 1) + { + char ssl_errstring[256]; + ERR_load_crypto_strings(); /*XXX move to a startup routine */ + ERR_error_string(ERR_get_error(), ssl_errstring); + ret = string_copy(ssl_errstring); + } +return ret; +} + + +#endif +/******************************************************************************/ + +#endif /*DISABLE_DKIM*/ +/* End of File */