--- /dev/null
+/*
+ * 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 */
git://git.exim.org / exim.git / blobdiff