/*************************************************************************** * _ _ ____ _ * Project ___| | | | _ \| | * / __| | | | |_) | | * | (__| |_| | _ <| |___ * \___|\___/|_| \_\_____| * * Copyright (C) Steve Holme, . * Copyright (C) Daniel Stenberg, , 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.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. * * SPDX-License-Identifier: curl * * RFC4752 The Kerberos V5 ("GSSAPI") SASL Mechanism * ***************************************************************************/ #include "curl_setup.h" #if defined(HAVE_GSSAPI) && defined(USE_KERBEROS5) #include #include "vauth/vauth.h" #include "curl_sasl.h" #include "urldata.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 username. * passwdp [in] - The user's password. * service [in] - The service type such as http, smtp, pop or imap. * host [in[ - The hostname. * mutual_auth [in] - Flag specifying whether or not mutual authentication * is enabled. * chlg [in] - Optional challenge message. * krb5 [in/out] - The Kerberos 5 data struct being used and modified. * out [out] - The result storage. * * 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 struct bufref *chlg, struct kerberos5data *krb5, struct bufref *out) { CURLcode result = CURLE_OK; 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_AUTH_ERROR; } free(spn); } if(chlg) { if(!Curl_bufref_len(chlg)) { infof(data, "GSSAPI handshake failure (empty challenge message)"); return CURLE_BAD_CONTENT_ENCODING; } input_token.value = (void *) Curl_bufref_ptr(chlg); input_token.length = Curl_bufref_len(chlg); } 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); 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_AUTH_ERROR; } if(output_token.value && output_token.length) { result = Curl_bufref_memdup(out, output_token.value, output_token.length); gss_release_buffer(&unused_status, &output_token); } else Curl_bufref_set(out, mutual_auth? "": NULL, 0, NULL); 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. * authzid [in] - The authorization identity if some. * chlg [in] - Optional challenge message. * krb5 [in/out] - The Kerberos 5 data struct being used and modified. * out [out] - The result storage. * * Returns CURLE_OK on success. */ CURLcode Curl_auth_create_gssapi_security_message(struct Curl_easy *data, const char *authzid, const struct bufref *chlg, struct kerberos5data *krb5, struct bufref *out) { CURLcode result = CURLE_OK; size_t messagelen = 0; 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 char *indata; gss_qop_t qop = GSS_C_QOP_DEFAULT; unsigned int sec_layer = 0; unsigned int max_size = 0; /* Ensure we have a valid challenge message */ if(!Curl_bufref_len(chlg)) { infof(data, "GSSAPI handshake failure (empty security message)"); return CURLE_BAD_CONTENT_ENCODING; } /* Setup the challenge "input" security buffer */ input_token.value = (void *) Curl_bufref_ptr(chlg); input_token.length = Curl_bufref_len(chlg); /* 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); 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)"); return CURLE_BAD_CONTENT_ENCODING; } /* Extract the security layer and the maximum message size */ indata = output_token.value; sec_layer = indata[0]; max_size = ((unsigned int)indata[1] << 16) | ((unsigned int)indata[2] << 8) | indata[3]; /* Free the challenge as it is not required anymore */ gss_release_buffer(&unused_status, &output_token); /* Process the security layer */ if(!(sec_layer & GSSAUTH_P_NONE)) { infof(data, "GSSAPI handshake failure (invalid security layer)"); return CURLE_BAD_CONTENT_ENCODING; } sec_layer &= GSSAUTH_P_NONE; /* We do not support a security layer */ /* Process the maximum message size the server can receive */ if(max_size > 0) { /* The server has told us it supports a maximum receive buffer, however, as we do not require one unless we are encrypting data, we tell the server our receive buffer is zero. */ max_size = 0; } /* Allocate our message */ messagelen = 4; if(authzid) messagelen += strlen(authzid); message = malloc(messagelen); if(!message) return CURLE_OUT_OF_MEMORY; /* Populate the message with the security layer and client supported receive message size. */ message[0] = sec_layer & 0xFF; message[1] = (max_size >> 16) & 0xFF; message[2] = (max_size >> 8) & 0xFF; message[3] = max_size & 0xFF; /* If given, append the authorization identity. */ if(authzid && *authzid) memcpy(message + 4, authzid, messagelen - 4); /* 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_AUTH_ERROR; } /* Return the response. */ result = Curl_bufref_memdup(out, output_token.value, output_token.length); /* 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 */