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-rw-r--r--src/scepclient/scep.c598
1 files changed, 598 insertions, 0 deletions
diff --git a/src/scepclient/scep.c b/src/scepclient/scep.c
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+++ b/src/scepclient/scep.c
@@ -0,0 +1,598 @@
+/**
+ * @file scep.c
+ * @brief SCEP specific functions
+ *
+ * Contains functions to build SCEP request's and to parse SCEP reply's.
+ */
+
+/*
+ * Copyright (C) 2005 Jan Hutter, Martin Willi
+ * Hochschule fuer Technik Rapperswil
+ *
+ * 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 (at your
+ * option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * 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.
+ */
+
+#include <string.h>
+#include <stdlib.h>
+
+#include <freeswan.h>
+
+#ifdef LIBCURL
+#include <curl/curl.h>
+#endif
+
+#include "../pluto/constants.h"
+#include "../pluto/defs.h"
+#include "../pluto/rnd.h"
+#include "../pluto/oid.h"
+#include "../pluto/asn1.h"
+#include "../pluto/pkcs1.h"
+#include "../pluto/fetch.h"
+#include "../pluto/log.h"
+
+#include "scep.h"
+
+static char ASN1_messageType_oid_str[] = {
+ 0x06, 0x0A, 0x60, 0x86, 0x48, 0x01, 0x86, 0xF8, 0x45, 0x01, 0x09, 0x02
+};
+
+static char ASN1_senderNonce_oid_str[] = {
+ 0x06, 0x0A, 0x60, 0x86, 0x48, 0x01, 0x86, 0xF8, 0x45, 0x01, 0x09, 0x05
+};
+
+static char ASN1_transId_oid_str[] = {
+ 0x06, 0x0A, 0x60, 0x86, 0x48, 0x01, 0x86, 0xF8, 0x45, 0x01, 0x09, 0x07
+};
+
+static const chunk_t ASN1_messageType_oid =
+ strchunk(ASN1_messageType_oid_str);
+static const chunk_t ASN1_senderNonce_oid =
+ strchunk(ASN1_senderNonce_oid_str);
+static const chunk_t ASN1_transId_oid =
+ strchunk(ASN1_transId_oid_str);
+
+static const char *pkiStatus_values[] = { "0", "2", "3" };
+
+static const char *pkiStatus_names[] = {
+ "SUCCESS",
+ "FAILURE",
+ "PENDING",
+ "UNKNOWN"
+};
+
+static const char *msgType_values[] = { "3", "19", "20", "21", "22" };
+
+static const char *msgType_names[] = {
+ "CertRep",
+ "PKCSReq",
+ "GetCertInitial",
+ "GetCert",
+ "GetCRL",
+ "Unknown"
+};
+
+static const char *failInfo_reasons[] = {
+ "badAlg - unrecognized or unsupported algorithm identifier",
+ "badMessageCheck - integrity check failed",
+ "badRequest - transaction not permitted or supported",
+ "badTime - Message time field was not sufficiently close to the system time",
+ "badCertId - No certificate could be identified matching the provided criteria"
+};
+
+const scep_attributes_t empty_scep_attributes = {
+ SCEP_Unknown_MSG , /* msgType */
+ SCEP_UNKNOWN , /* pkiStatus */
+ SCEP_unknown_REASON, /* failInfo */
+ { NULL, 0 } , /* transID */
+ { NULL, 0 } , /* senderNonce */
+ { NULL, 0 } , /* recipientNonce */
+};
+
+/* ASN.1 definition of the X.501 atttribute type */
+
+static const asn1Object_t attributesObjects[] = {
+ { 0, "attributes", ASN1_SET, ASN1_LOOP }, /* 0 */
+ { 1, "attribute", ASN1_SEQUENCE, ASN1_NONE }, /* 1 */
+ { 2, "type", ASN1_OID, ASN1_BODY }, /* 2 */
+ { 2, "values", ASN1_SET, ASN1_LOOP }, /* 3 */
+ { 3, "value", ASN1_EOC, ASN1_RAW }, /* 4 */
+ { 2, "end loop", ASN1_EOC, ASN1_END }, /* 5 */
+ { 0, "end loop", ASN1_EOC, ASN1_END }, /* 6 */
+};
+
+#define ATTRIBUTE_OBJ_TYPE 2
+#define ATTRIBUTE_OBJ_VALUE 4
+#define ATTRIBUTE_OBJ_ROOF 7
+
+/*
+ * extract and store an attribute
+ */
+static bool
+extract_attribute(int oid, chunk_t object, u_int level
+, scep_attributes_t *attrs)
+{
+ asn1_t type = ASN1_EOC;
+ const char *name = "none";
+
+ switch (oid)
+ {
+ case OID_PKCS9_CONTENT_TYPE:
+ type = ASN1_OID;
+ name = "contentType";
+ break;
+ case OID_PKCS9_SIGNING_TIME:
+ type = ASN1_UTCTIME;
+ name = "signingTime";
+ break;
+ case OID_PKCS9_MESSAGE_DIGEST:
+ type = ASN1_OCTET_STRING;
+ name = "messageDigest";
+ break;
+ case OID_PKI_MESSAGE_TYPE:
+ type = ASN1_PRINTABLESTRING;
+ name = "messageType";
+ break;
+ case OID_PKI_STATUS:
+ type = ASN1_PRINTABLESTRING;
+ name = "pkiStatus";
+ break;
+ case OID_PKI_FAIL_INFO:
+ type = ASN1_PRINTABLESTRING;
+ name = "failInfo";
+ break;
+ case OID_PKI_SENDER_NONCE:
+ type = ASN1_OCTET_STRING;
+ name = "senderNonce";
+ break;
+ case OID_PKI_RECIPIENT_NONCE:
+ type = ASN1_OCTET_STRING;
+ name = "recipientNonce";
+ break;
+ case OID_PKI_TRANS_ID:
+ type = ASN1_PRINTABLESTRING;
+ name = "transID";
+ break;
+ default:
+ break;
+ }
+
+ if (type == ASN1_EOC)
+ return TRUE;
+
+ if (!parse_asn1_simple_object(&object, type, level+1, name))
+ return FALSE;
+
+ switch (oid)
+ {
+ case OID_PKCS9_CONTENT_TYPE:
+ break;
+ case OID_PKCS9_SIGNING_TIME:
+ break;
+ case OID_PKCS9_MESSAGE_DIGEST:
+ break;
+ case OID_PKI_MESSAGE_TYPE:
+ {
+ scep_msg_t m;
+
+ for (m = SCEP_CertRep_MSG; m < SCEP_Unknown_MSG; m++)
+ {
+ if (strncmp(msgType_values[m], object.ptr, object.len) == 0)
+ attrs->msgType = m;
+ }
+ DBG(DBG_CONTROL,
+ DBG_log("messageType: %s", msgType_names[attrs->msgType])
+ )
+ }
+ break;
+ case OID_PKI_STATUS:
+ {
+ pkiStatus_t s;
+
+ for (s = SCEP_SUCCESS; s < SCEP_UNKNOWN; s++)
+ {
+ if (strncmp(pkiStatus_values[s], object.ptr, object.len) == 0)
+ attrs->pkiStatus = s;
+ }
+ DBG(DBG_CONTROL,
+ DBG_log("pkiStatus: %s", pkiStatus_names[attrs->pkiStatus])
+ )
+ }
+ break;
+ case OID_PKI_FAIL_INFO:
+ if (object.len == 1
+ && *object.ptr >= '0' && *object.ptr <= '4')
+ {
+ attrs->failInfo = (failInfo_t)(*object.ptr - '0');
+ }
+ if (attrs->failInfo != SCEP_unknown_REASON)
+ plog("failInfo: %s", failInfo_reasons[attrs->failInfo]);
+ break;
+ case OID_PKI_SENDER_NONCE:
+ attrs->senderNonce = object;
+ break;
+ case OID_PKI_RECIPIENT_NONCE:
+ attrs->recipientNonce = object;
+ break;
+ case OID_PKI_TRANS_ID:
+ attrs->transID = object;
+ }
+ return TRUE;
+}
+
+/*
+ * parse X.501 attributes
+ */
+bool
+parse_attributes(chunk_t blob, scep_attributes_t *attrs)
+{
+ asn1_ctx_t ctx;
+ chunk_t object;
+ u_int level;
+ int oid = OID_UNKNOWN;
+ int objectID = 0;
+
+ asn1_init(&ctx, blob, 0, FALSE, DBG_RAW);
+
+ DBG(DBG_CONTROL | DBG_PARSING,
+ DBG_log("parsing attributes")
+ )
+ while (objectID < ATTRIBUTE_OBJ_ROOF)
+ {
+ if (!extract_object(attributesObjects, &objectID
+ , &object, &level, &ctx))
+ return FALSE;
+
+ switch (objectID)
+ {
+ case ATTRIBUTE_OBJ_TYPE:
+ oid = known_oid(object);
+ break;
+ case ATTRIBUTE_OBJ_VALUE:
+ if (!extract_attribute(oid, object, level, attrs))
+ return FALSE;
+ }
+ objectID++;
+ }
+ return TRUE;
+}
+
+/* generates a unique fingerprint of the pkcs10 request
+ * by computing an MD5 hash over it
+ */
+void
+scep_generate_pkcs10_fingerprint(chunk_t pkcs10, chunk_t *fingerprint)
+{
+ char buf[MD5_DIGEST_SIZE];
+ chunk_t digest = { buf, sizeof(buf) };
+
+ /* the fingerprint is the MD5 hash in hexadecimal format */
+ compute_digest(pkcs10, OID_MD5, &digest);
+ fingerprint->len = 2*digest.len;
+ fingerprint->ptr = alloc_bytes(fingerprint->len + 1, "fingerprint");
+ datatot(digest.ptr, digest.len, 16, fingerprint->ptr, fingerprint->len + 1);
+}
+
+/* generate a transaction id as the MD5 hash of an public key
+ * the transaction id is also used as a unique serial number
+ */
+void
+scep_generate_transaction_id(const RSA_public_key_t *rsak
+, chunk_t *transID, chunk_t *serialNumber)
+{
+ char buf[MD5_DIGEST_SIZE];
+
+ chunk_t digest = { buf, sizeof(buf) };
+ chunk_t public_key = pkcs1_build_publicKeyInfo(rsak);
+
+ bool msb_set;
+ u_char *pos;
+
+ compute_digest(public_key, OID_MD5, &digest);
+ pfree(public_key.ptr);
+
+ /* is the most significant bit of the digest set? */
+ msb_set = (*digest.ptr & 0x80) == 0x80;
+
+ /* allocate space for the serialNumber */
+ serialNumber->len = msb_set + digest.len;
+ serialNumber->ptr = alloc_bytes(serialNumber->len, "serialNumber");
+
+ /* the serial number as the two's complement of the digest */
+ pos = serialNumber->ptr;
+ if (msb_set)
+ {
+ *pos++ = 0x00;
+ }
+ memcpy(pos, digest.ptr, digest.len);
+
+ /* the transaction id is the serial number in hex format */
+ transID->len = 2*digest.len;
+ transID->ptr = alloc_bytes(transID->len + 1, "transID");
+ datatot(digest.ptr, digest.len, 16, transID->ptr, transID->len + 1);
+}
+
+/*
+ * builds a transId attribute
+ */
+chunk_t
+scep_transId_attribute(chunk_t transID)
+{
+ return asn1_wrap(ASN1_SEQUENCE, "cm"
+ , ASN1_transId_oid
+ , asn1_wrap(ASN1_SET, "m"
+ , asn1_simple_object(ASN1_PRINTABLESTRING, transID)
+ )
+ );
+}
+
+/*
+ * builds a messageType attribute
+ */
+chunk_t
+scep_messageType_attribute(scep_msg_t m)
+{
+ chunk_t msgType = {
+ msgType_values[m],
+ strlen(msgType_values[m])
+ };
+
+ return asn1_wrap(ASN1_SEQUENCE, "cm"
+ , ASN1_messageType_oid
+ , asn1_wrap(ASN1_SET, "m"
+ , asn1_simple_object(ASN1_PRINTABLESTRING, msgType)
+ )
+ );
+}
+
+/*
+ * builds a senderNonce attribute
+ */
+chunk_t
+scep_senderNonce_attribute(void)
+{
+ const size_t nonce_len = 16;
+ u_char nonce_buf[nonce_len];
+ chunk_t senderNonce = { nonce_buf, nonce_len };
+
+ get_rnd_bytes(nonce_buf, nonce_len);
+
+ return asn1_wrap(ASN1_SEQUENCE, "cm"
+ , ASN1_senderNonce_oid
+ , asn1_wrap(ASN1_SET, "m"
+ , asn1_simple_object(ASN1_OCTET_STRING, senderNonce)
+ )
+ );
+}
+
+/*
+ * builds a pkcs7 enveloped and signed scep request
+ */
+chunk_t
+scep_build_request(chunk_t data, chunk_t transID, scep_msg_t msg
+, const x509cert_t *enc_cert, int enc_alg
+, const x509cert_t *signer_cert, int digest_alg
+, const RSA_private_key_t *private_key)
+{
+ chunk_t envelopedData, attributes, request;
+
+ envelopedData = pkcs7_build_envelopedData(data, enc_cert, enc_alg);
+
+ attributes = asn1_wrap(ASN1_SET, "mmmmm"
+ , pkcs7_contentType_attribute()
+ , pkcs7_messageDigest_attribute(envelopedData
+ , digest_alg)
+ , scep_transId_attribute(transID)
+ , scep_messageType_attribute(msg)
+ , scep_senderNonce_attribute());
+
+ request = pkcs7_build_signedData(envelopedData, attributes
+ , signer_cert, digest_alg, private_key);
+ freeanychunk(envelopedData);
+ freeanychunk(attributes);
+ return request;
+}
+
+#ifdef LIBCURL
+/* converts a binary request to base64 with 64 characters per line
+ * newline and '+' characters are escaped by %0A and %2B, respectively
+ */
+static char*
+escape_http_request(chunk_t req)
+{
+ char *escaped_req = NULL;
+ char *p1, *p2;
+ int lines = 0;
+ int plus = 0;
+ int n = 0;
+
+ /* compute and allocate the size of the base64-encoded request */
+ int len = 1 + 4*((req.len + 2)/3);
+ char *encoded_req = alloc_bytes(len, "encoded request");
+
+ /* do the base64 conversion */
+ len = datatot(req.ptr, req.len, 64, encoded_req, len);
+
+ /* compute newline characters to be inserted every 64 characters */
+ lines = (len - 2) / 64;
+
+ /* count number of + characters to be escaped */
+ p1 = encoded_req;
+ while (*p1 != '\0')
+ {
+ if (*p1++ == '+')
+ plus++;
+ }
+
+ escaped_req = alloc_bytes(len + 3*(lines + plus), "escaped request");
+
+ /* escape special characters in the request */
+ p1 = encoded_req;
+ p2 = escaped_req;
+ while (*p1 != '\0')
+ {
+ if (n == 64)
+ {
+ memcpy(p2, "%0A", 3);
+ p2 += 3;
+ n = 0;
+ }
+ if (*p1 == '+')
+ {
+ memcpy(p2, "%2B", 3);
+ p2 += 3;
+ }
+ else
+ {
+ *p2++ = *p1;
+ }
+ p1++;
+ n++;
+ }
+ *p2 = '\0';
+ pfreeany(encoded_req);
+ return escaped_req;
+}
+#endif
+
+/*
+ * send a SCEP request via HTTP and wait for a response
+ */
+bool
+scep_http_request(const char *url, chunk_t pkcs7, scep_op_t op
+, fetch_request_t req_type, chunk_t *response)
+{
+#ifdef LIBCURL
+ char errorbuffer[CURL_ERROR_SIZE] = "";
+ char *complete_url = NULL;
+ struct curl_slist *headers = NULL;
+ CURL *curl;
+ CURLcode res;
+
+ /* initialize response */
+ *response = empty_chunk;
+
+ /* initialize curl context */
+ curl = curl_easy_init();
+ if (curl == NULL)
+ {
+ plog("could not initialize curl context");
+ return FALSE;
+ }
+
+ if (op == SCEP_PKI_OPERATION)
+ {
+ const char operation[] = "PKIOperation";
+
+ if (req_type == FETCH_GET)
+ {
+ char *escaped_req = escape_http_request(pkcs7);
+
+ /* form complete url */
+ int len = strlen(url) + 20 + strlen(operation) + strlen(escaped_req) + 1;
+
+ complete_url = alloc_bytes(len, "complete url");
+ snprintf(complete_url, len, "%s?operation=%s&message=%s"
+ , url, operation, escaped_req);
+ pfreeany(escaped_req);
+
+ curl_easy_setopt(curl, CURLOPT_HTTPGET, TRUE);
+ headers = curl_slist_append(headers, "Pragma:");
+ headers = curl_slist_append(headers, "Host:");
+ headers = curl_slist_append(headers, "Accept:");
+ curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
+ curl_easy_setopt(curl, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_0);
+ }
+ else /* HTTP_POST */
+ {
+ /* form complete url */
+ int len = strlen(url) + 11 + strlen(operation) + 1;
+
+ complete_url = alloc_bytes(len, "complete url");
+ snprintf(complete_url, len, "%s?operation=%s", url, operation);
+
+ curl_easy_setopt(curl, CURLOPT_HTTPGET, FALSE);
+ headers = curl_slist_append(headers, "Content-Type:");
+ headers = curl_slist_append(headers, "Expect:");
+ curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
+ curl_easy_setopt(curl, CURLOPT_POSTFIELDS, pkcs7.ptr);
+ curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, pkcs7.len);
+ }
+ }
+ else /* SCEP_GET_CA_CERT */
+ {
+ const char operation[] = "GetCACert";
+
+ /* form complete url */
+ int len = strlen(url) + 32 + strlen(operation) + 1;
+
+ complete_url = alloc_bytes(len, "complete url");
+ snprintf(complete_url, len, "%s?operation=%s&message=CAIdentifier"
+ , url, operation);
+
+ curl_easy_setopt(curl, CURLOPT_HTTPGET, TRUE);
+ }
+
+ curl_easy_setopt(curl, CURLOPT_URL, complete_url);
+ curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_buffer);
+ curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)response);
+ curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, errorbuffer);
+ curl_easy_setopt(curl, CURLOPT_FAILONERROR, TRUE);
+ curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, FETCH_CMD_TIMEOUT);
+
+ DBG(DBG_CONTROL,
+ DBG_log("sending scep request to '%s'", url)
+ )
+ res = curl_easy_perform(curl);
+
+ if (res == CURLE_OK)
+ {
+ DBG(DBG_CONTROL,
+ DBG_log("received scep response")
+ )
+ DBG(DBG_RAW,
+ DBG_dump_chunk("SCEP response:\n", *response)
+ )
+ }
+ else
+ {
+ plog("failed to fetch scep response from '%s': %s", url, errorbuffer);
+ }
+ curl_slist_free_all(headers);
+ curl_easy_cleanup(curl);
+ pfreeany(complete_url);
+
+ return (res == CURLE_OK);
+#else /* !LIBCURL */
+ plog("scep error: pluto wasn't compiled with libcurl support");
+ return FALSE;
+#endif /* !LIBCURL */
+}
+
+err_t
+scep_parse_response(chunk_t response, chunk_t transID, contentInfo_t *data
+, scep_attributes_t *attrs, x509cert_t *signer_cert)
+{
+ chunk_t attributes;
+
+ if (!pkcs7_parse_signedData(response, data, NULL, &attributes, signer_cert))
+ {
+ return "error parsing the scep response";
+ }
+ if (!parse_attributes(attributes, attrs))
+ {
+ return "error parsing the scep response attributes";
+ }
+ if (!same_chunk(transID, attrs->transID))
+ {
+ return "transaction ID of scep response does not match";
+ }
+ return NULL;
+}
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