/*************************************************************************** * _ _ ____ _ * Project ___| | | | _ \| | * / __| | | | |_) | | * | (__| |_| | _ <| |___ * \___|\___/|_| \_\_____| * * Copyright (C) 2014 - 2019, Steve Holme, <steve_holme@hotmail.com>. * Copyright (C) 2015, Daniel Stenberg, <daniel@haxx.se>, et al. * * This software is licensed as described in the file COPYING, which * you should have received as part of this distribution. The terms * are also available at https://curl.haxx.se/docs/copyright.html. * * You may opt to use, copy, modify, merge, publish, distribute and/or sell * copies of the Software, and permit persons to whom the Software is * furnished to do so, under the terms of the COPYING file. * * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY * KIND, either express or implied. * * RFC4752 The Kerberos V5 ("GSSAPI") SASL Mechanism * ***************************************************************************/ #include "curl_setup.h" #if defined(HAVE_GSSAPI) && defined(USE_KERBEROS5) #include <curl/curl.h> #include "vauth/vauth.h" #include "curl_sasl.h" #include "urldata.h" #include "curl_base64.h" #include "curl_gssapi.h" #include "sendf.h" #include "curl_printf.h" /* The last #include files should be: */ #include "curl_memory.h" #include "memdebug.h" /* * Curl_auth_is_gssapi_supported() * * This is used to evaluate if GSSAPI (Kerberos V5) is supported. * * Parameters: None * * Returns TRUE if Kerberos V5 is supported by the GSS-API library. */ bool Curl_auth_is_gssapi_supported(void) { return TRUE; } /* * Curl_auth_create_gssapi_user_message() * * This is used to generate an already encoded GSSAPI (Kerberos V5) user token * message ready for sending to the recipient. * * Parameters: * * data [in] - The session handle. * userp [in] - The user name. * passwdp [in] - The user's password. * service [in] - The service type such as http, smtp, pop or imap. * host [in[ - The host name. * mutual_auth [in] - Flag specifying whether or not mutual authentication * is enabled. * chlg64 [in] - Pointer to the optional base64 encoded challenge * message. * krb5 [in/out] - The Kerberos 5 data struct being used and modified. * outptr [in/out] - The address where a pointer to newly allocated memory * holding the result will be stored upon completion. * outlen [out] - The length of the output message. * * Returns CURLE_OK on success. */ CURLcode Curl_auth_create_gssapi_user_message(struct Curl_easy *data, const char *userp, const char *passwdp, const char *service, const char *host, const bool mutual_auth, const char *chlg64, struct kerberos5data *krb5, char **outptr, size_t *outlen) { CURLcode result = CURLE_OK; size_t chlglen = 0; unsigned char *chlg = NULL; OM_uint32 major_status; OM_uint32 minor_status; OM_uint32 unused_status; gss_buffer_desc spn_token = GSS_C_EMPTY_BUFFER; gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER; gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER; (void) userp; (void) passwdp; if(!krb5->spn) { /* Generate our SPN */ char *spn = Curl_auth_build_spn(service, NULL, host); if(!spn) return CURLE_OUT_OF_MEMORY; /* Populate the SPN structure */ spn_token.value = spn; spn_token.length = strlen(spn); /* Import the SPN */ major_status = gss_import_name(&minor_status, &spn_token, GSS_C_NT_HOSTBASED_SERVICE, &krb5->spn); if(GSS_ERROR(major_status)) { Curl_gss_log_error(data, "gss_import_name() failed: ", major_status, minor_status); free(spn); return CURLE_OUT_OF_MEMORY; } free(spn); } if(chlg64 && *chlg64) { /* Decode the base-64 encoded challenge message */ if(*chlg64 != '=') { result = Curl_base64_decode(chlg64, &chlg, &chlglen); if(result) return result; } /* Ensure we have a valid challenge message */ if(!chlg) { infof(data, "GSSAPI handshake failure (empty challenge message)\n"); return CURLE_BAD_CONTENT_ENCODING; } /* Setup the challenge "input" security buffer */ input_token.value = chlg; input_token.length = chlglen; } major_status = Curl_gss_init_sec_context(data, &minor_status, &krb5->context, krb5->spn, &Curl_krb5_mech_oid, GSS_C_NO_CHANNEL_BINDINGS, &input_token, &output_token, mutual_auth, NULL); /* Free the decoded challenge as it is not required anymore */ free(input_token.value); if(GSS_ERROR(major_status)) { if(output_token.value) gss_release_buffer(&unused_status, &output_token); Curl_gss_log_error(data, "gss_init_sec_context() failed: ", major_status, minor_status); return CURLE_RECV_ERROR; } if(output_token.value && output_token.length) { /* Base64 encode the response */ result = Curl_base64_encode(data, (char *) output_token.value, output_token.length, outptr, outlen); gss_release_buffer(&unused_status, &output_token); } else if(mutual_auth) { *outptr = strdup(""); if(!*outptr) result = CURLE_OUT_OF_MEMORY; } return result; } /* * Curl_auth_create_gssapi_security_message() * * This is used to generate an already encoded GSSAPI (Kerberos V5) security * token message ready for sending to the recipient. * * Parameters: * * data [in] - The session handle. * chlg64 [in] - Pointer to the optional base64 encoded challenge message. * krb5 [in/out] - The Kerberos 5 data struct being used and modified. * outptr [in/out] - The address where a pointer to newly allocated memory * holding the result will be stored upon completion. * outlen [out] - The length of the output message. * * Returns CURLE_OK on success. */ CURLcode Curl_auth_create_gssapi_security_message(struct Curl_easy *data, const char *chlg64, struct kerberos5data *krb5, char **outptr, size_t *outlen) { CURLcode result = CURLE_OK; size_t chlglen = 0; size_t messagelen = 0; unsigned char *chlg = NULL; unsigned char *message = NULL; OM_uint32 major_status; OM_uint32 minor_status; OM_uint32 unused_status; gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER; gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER; unsigned int indata = 0; unsigned int outdata = 0; gss_qop_t qop = GSS_C_QOP_DEFAULT; unsigned int sec_layer = 0; unsigned int max_size = 0; gss_name_t username = GSS_C_NO_NAME; gss_buffer_desc username_token; /* Decode the base-64 encoded input message */ if(strlen(chlg64) && *chlg64 != '=') { result = Curl_base64_decode(chlg64, &chlg, &chlglen); if(result) return result; } /* Ensure we have a valid challenge message */ if(!chlg) { infof(data, "GSSAPI handshake failure (empty security message)\n"); return CURLE_BAD_CONTENT_ENCODING; } /* Get the fully qualified username back from the context */ major_status = gss_inquire_context(&minor_status, krb5->context, &username, NULL, NULL, NULL, NULL, NULL, NULL); if(GSS_ERROR(major_status)) { Curl_gss_log_error(data, "gss_inquire_context() failed: ", major_status, minor_status); free(chlg); return CURLE_OUT_OF_MEMORY; } /* Convert the username from internal format to a displayable token */ major_status = gss_display_name(&minor_status, username, &username_token, NULL); if(GSS_ERROR(major_status)) { Curl_gss_log_error(data, "gss_display_name() failed: ", major_status, minor_status); free(chlg); return CURLE_OUT_OF_MEMORY; } /* Setup the challenge "input" security buffer */ input_token.value = chlg; input_token.length = chlglen; /* Decrypt the inbound challenge and obtain the qop */ major_status = gss_unwrap(&minor_status, krb5->context, &input_token, &output_token, NULL, &qop); if(GSS_ERROR(major_status)) { Curl_gss_log_error(data, "gss_unwrap() failed: ", major_status, minor_status); gss_release_buffer(&unused_status, &username_token); free(chlg); return CURLE_BAD_CONTENT_ENCODING; } /* Not 4 octets long so fail as per RFC4752 Section 3.1 */ if(output_token.length != 4) { infof(data, "GSSAPI handshake failure (invalid security data)\n"); gss_release_buffer(&unused_status, &username_token); free(chlg); return CURLE_BAD_CONTENT_ENCODING; } /* Copy the data out and free the challenge as it is not required anymore */ memcpy(&indata, output_token.value, 4); gss_release_buffer(&unused_status, &output_token); free(chlg); /* Extract the security layer */ sec_layer = indata & 0x000000FF; if(!(sec_layer & GSSAUTH_P_NONE)) { infof(data, "GSSAPI handshake failure (invalid security layer)\n"); gss_release_buffer(&unused_status, &username_token); return CURLE_BAD_CONTENT_ENCODING; } /* Extract the maximum message size the server can receive */ max_size = ntohl(indata & 0xFFFFFF00); if(max_size > 0) { /* The server has told us it supports a maximum receive buffer, however, as we don't require one unless we are encrypting data, we tell the server our receive buffer is zero. */ max_size = 0; } /* Allocate our message */ messagelen = sizeof(outdata) + username_token.length + 1; message = malloc(messagelen); if(!message) { gss_release_buffer(&unused_status, &username_token); return CURLE_OUT_OF_MEMORY; } /* Populate the message with the security layer, client supported receive message size and authorization identity including the 0x00 based terminator. Note: Despite RFC4752 Section 3.1 stating "The authorization identity is not terminated with the zero-valued (%x00) octet." it seems necessary to include it. */ outdata = htonl(max_size) | sec_layer; memcpy(message, &outdata, sizeof(outdata)); memcpy(message + sizeof(outdata), username_token.value, username_token.length); message[messagelen - 1] = '\0'; /* Free the username token as it is not required anymore */ gss_release_buffer(&unused_status, &username_token); /* Setup the "authentication data" security buffer */ input_token.value = message; input_token.length = messagelen; /* Encrypt the data */ major_status = gss_wrap(&minor_status, krb5->context, 0, GSS_C_QOP_DEFAULT, &input_token, NULL, &output_token); if(GSS_ERROR(major_status)) { Curl_gss_log_error(data, "gss_wrap() failed: ", major_status, minor_status); free(message); return CURLE_OUT_OF_MEMORY; } /* Base64 encode the response */ result = Curl_base64_encode(data, (char *) output_token.value, output_token.length, outptr, outlen); /* Free the output buffer */ gss_release_buffer(&unused_status, &output_token); /* Free the message buffer */ free(message); return result; } /* * Curl_auth_cleanup_gssapi() * * This is used to clean up the GSSAPI (Kerberos V5) specific data. * * Parameters: * * krb5 [in/out] - The Kerberos 5 data struct being cleaned up. * */ void Curl_auth_cleanup_gssapi(struct kerberos5data *krb5) { OM_uint32 minor_status; /* Free our security context */ if(krb5->context != GSS_C_NO_CONTEXT) { gss_delete_sec_context(&minor_status, &krb5->context, GSS_C_NO_BUFFER); krb5->context = GSS_C_NO_CONTEXT; } /* Free the SPN */ if(krb5->spn != GSS_C_NO_NAME) { gss_release_name(&minor_status, &krb5->spn); krb5->spn = GSS_C_NO_NAME; } } #endif /* HAVE_GSSAPI && USE_KERBEROS5 */