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curl/lib/curl_sasl.c
Steve Holme e655ae0c80 curl_sasl: Fixed potential null pointer utilisation 
Although this should never happen due to the relationship between the
'mech' and 'resp' variables, and the way they are allocated together,
it does cause problems for code analysis tools:

V595 The 'mech' pointer was utilized before it was verified against
     nullptr. Check lines: 376, 381. curl_sasl.c 376

Bug: https://github.com/curl/curl/issues/745
Reported-by: Alexis La Goutte
2016-04-03 17:55:17 +01:00

609 lines
19 KiB
C
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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 2012 - 2016, 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.
*
* RFC2195 CRAM-MD5 authentication
* RFC2617 Basic and Digest Access Authentication
* RFC2831 DIGEST-MD5 authentication
* RFC4422 Simple Authentication and Security Layer (SASL)
* RFC4616 PLAIN authentication
* RFC6749 OAuth 2.0 Authorization Framework
* RFC7628 A Set of SASL Mechanisms for OAuth
* Draft LOGIN SASL Mechanism <draft-murchison-sasl-login-00.txt>
*
***************************************************************************/
#include "curl_setup.h"
#include <curl/curl.h>
#include "urldata.h"
#include "curl_base64.h"
#include "curl_md5.h"
#include "vauth/vauth.h"
#include "vtls/vtls.h"
#include "curl_hmac.h"
#include "curl_sasl.h"
#include "warnless.h"
#include "strtok.h"
#include "strequal.h"
#include "rawstr.h"
#include "sendf.h"
#include "non-ascii.h" /* included for Curl_convert_... prototypes */
#include "curl_printf.h"
/* The last #include files should be: */
#include "curl_memory.h"
#include "memdebug.h"
/* Supported mechanisms */
const struct {
const char *name; /* Name */
size_t len; /* Name length */
unsigned int bit; /* Flag bit */
} mechtable[] = {
{ "LOGIN", 5, SASL_MECH_LOGIN },
{ "PLAIN", 5, SASL_MECH_PLAIN },
{ "CRAM-MD5", 8, SASL_MECH_CRAM_MD5 },
{ "DIGEST-MD5", 10, SASL_MECH_DIGEST_MD5 },
{ "GSSAPI", 6, SASL_MECH_GSSAPI },
{ "EXTERNAL", 8, SASL_MECH_EXTERNAL },
{ "NTLM", 4, SASL_MECH_NTLM },
{ "XOAUTH2", 7, SASL_MECH_XOAUTH2 },
{ "OAUTHBEARER", 11, SASL_MECH_OAUTHBEARER },
{ ZERO_NULL, 0, 0 }
};
/*
* Curl_sasl_cleanup()
*
* This is used to cleanup any libraries or curl modules used by the sasl
* functions.
*
* Parameters:
*
* conn [in] - The connection data.
* authused [in] - The authentication mechanism used.
*/
void Curl_sasl_cleanup(struct connectdata *conn, unsigned int authused)
{
#if defined(USE_KERBEROS5)
/* Cleanup the gssapi structure */
if(authused == SASL_MECH_GSSAPI) {
Curl_auth_gssapi_cleanup(&conn->krb5);
}
#endif
#if defined(USE_NTLM)
/* Cleanup the NTLM structure */
if(authused == SASL_MECH_NTLM) {
Curl_auth_ntlm_cleanup(&conn->ntlm);
}
#endif
#if !defined(USE_KERBEROS5) && !defined(USE_NTLM)
/* Reserved for future use */
(void)conn;
(void)authused;
#endif
}
/*
* Curl_sasl_decode_mech()
*
* Convert a SASL mechanism name into a token.
*
* Parameters:
*
* ptr [in] - The mechanism string.
* maxlen [in] - Maximum mechanism string length.
* len [out] - If not NULL, effective name length.
*
* Returns the SASL mechanism token or 0 if no match.
*/
unsigned int Curl_sasl_decode_mech(const char *ptr, size_t maxlen, size_t *len)
{
unsigned int i;
char c;
for(i = 0; mechtable[i].name; i++) {
if(maxlen >= mechtable[i].len &&
!memcmp(ptr, mechtable[i].name, mechtable[i].len)) {
if(len)
*len = mechtable[i].len;
if(maxlen == mechtable[i].len)
return mechtable[i].bit;
c = ptr[mechtable[i].len];
if(!ISUPPER(c) && !ISDIGIT(c) && c != '-' && c != '_')
return mechtable[i].bit;
}
}
return 0;
}
/*
* Curl_sasl_parse_url_auth_option()
*
* Parse the URL login options.
*/
CURLcode Curl_sasl_parse_url_auth_option(struct SASL *sasl,
const char *value, size_t len)
{
CURLcode result = CURLE_OK;
unsigned int mechbit;
size_t mechlen;
if(!len)
return CURLE_URL_MALFORMAT;
if(sasl->resetprefs) {
sasl->resetprefs = FALSE;
sasl->prefmech = SASL_AUTH_NONE;
}
if(strnequal(value, "*", len))
sasl->prefmech = SASL_AUTH_DEFAULT;
else {
mechbit = Curl_sasl_decode_mech(value, len, &mechlen);
if(mechbit && mechlen == len)
sasl->prefmech |= mechbit;
else
result = CURLE_URL_MALFORMAT;
}
return result;
}
/*
* Curl_sasl_init()
*
* Initializes the SASL structure.
*/
void Curl_sasl_init(struct SASL *sasl, const struct SASLproto *params)
{
sasl->params = params; /* Set protocol dependent parameters */
sasl->state = SASL_STOP; /* Not yet running */
sasl->authmechs = SASL_AUTH_NONE; /* No known authentication mechanism yet */
sasl->prefmech = SASL_AUTH_DEFAULT; /* Prefer all mechanisms */
sasl->authused = SASL_AUTH_NONE; /* No the authentication mechanism used */
sasl->resetprefs = TRUE; /* Reset prefmech upon AUTH parsing. */
sasl->mutual_auth = FALSE; /* No mutual authentication (GSSAPI only) */
sasl->force_ir = FALSE; /* Respect external option */
}
/*
* state()
*
* This is the ONLY way to change SASL state!
*/
static void state(struct SASL *sasl, struct connectdata *conn,
saslstate newstate)
{
#if defined(DEBUGBUILD) && !defined(CURL_DISABLE_VERBOSE_STRINGS)
/* for debug purposes */
static const char * const names[]={
"STOP",
"PLAIN",
"LOGIN",
"LOGIN_PASSWD",
"EXTERNAL",
"CRAMMD5",
"DIGESTMD5",
"DIGESTMD5_RESP",
"NTLM",
"NTLM_TYPE2MSG",
"GSSAPI",
"GSSAPI_TOKEN",
"GSSAPI_NO_DATA",
"OAUTH2",
"OAUTH2_RESP",
"CANCEL",
"FINAL",
/* LAST */
};
if(sasl->state != newstate)
infof(conn->data, "SASL %p state change from %s to %s\n",
(void *)sasl, names[sasl->state], names[newstate]);
#else
(void) conn;
#endif
sasl->state = newstate;
}
/*
* Curl_sasl_can_authenticate()
*
* Check if we have enough auth data and capabilities to authenticate.
*/
bool Curl_sasl_can_authenticate(struct SASL *sasl, struct connectdata *conn)
{
/* Have credentials been provided? */
if(conn->bits.user_passwd)
return TRUE;
/* EXTERNAL can authenticate without a user name and/or password */
if(sasl->authmechs & sasl->prefmech & SASL_MECH_EXTERNAL)
return TRUE;
return FALSE;
}
/*
* Curl_sasl_start()
*
* Calculate the required login details for SASL authentication.
*/
CURLcode Curl_sasl_start(struct SASL *sasl, struct connectdata *conn,
bool force_ir, saslprogress *progress)
{
CURLcode result = CURLE_OK;
struct SessionHandle *data = conn->data;
unsigned int enabledmechs;
const char *mech = NULL;
char *resp = NULL;
size_t len = 0;
saslstate state1 = SASL_STOP;
saslstate state2 = SASL_FINAL;
sasl->force_ir = force_ir; /* Latch for future use */
sasl->authused = 0; /* No mechanism used yet */
enabledmechs = sasl->authmechs & sasl->prefmech;
*progress = SASL_IDLE;
/* Calculate the supported authentication mechanism, by decreasing order of
security, as well as the initial response where appropriate */
if((enabledmechs & SASL_MECH_EXTERNAL) && !conn->passwd[0]) {
mech = SASL_MECH_STRING_EXTERNAL;
state1 = SASL_EXTERNAL;
sasl->authused = SASL_MECH_EXTERNAL;
if(force_ir || data->set.sasl_ir)
result = Curl_auth_create_external_message(data, conn->user, &resp,
&len);
}
else if(conn->bits.user_passwd) {
#if defined(USE_KERBEROS5)
if(enabledmechs & SASL_MECH_GSSAPI) {
sasl->mutual_auth = FALSE; /* TODO: Calculate mutual authentication */
mech = SASL_MECH_STRING_GSSAPI;
state1 = SASL_GSSAPI;
state2 = SASL_GSSAPI_TOKEN;
sasl->authused = SASL_MECH_GSSAPI;
if(force_ir || data->set.sasl_ir)
result = Curl_auth_create_gssapi_user_message(data, conn->user,
conn->passwd,
sasl->params->service,
data->easy_conn->
host.name,
sasl->mutual_auth,
NULL, &conn->krb5,
&resp, &len);
}
else
#endif
#ifndef CURL_DISABLE_CRYPTO_AUTH
if(enabledmechs & SASL_MECH_DIGEST_MD5) {
mech = SASL_MECH_STRING_DIGEST_MD5;
state1 = SASL_DIGESTMD5;
sasl->authused = SASL_MECH_DIGEST_MD5;
}
else if(enabledmechs & SASL_MECH_CRAM_MD5) {
mech = SASL_MECH_STRING_CRAM_MD5;
state1 = SASL_CRAMMD5;
sasl->authused = SASL_MECH_CRAM_MD5;
}
else
#endif
#ifdef USE_NTLM
if(enabledmechs & SASL_MECH_NTLM) {
mech = SASL_MECH_STRING_NTLM;
state1 = SASL_NTLM;
state2 = SASL_NTLM_TYPE2MSG;
sasl->authused = SASL_MECH_NTLM;
if(force_ir || data->set.sasl_ir)
result = Curl_auth_create_ntlm_type1_message(conn->user, conn->passwd,
&conn->ntlm, &resp, &len);
}
else
#endif
if((enabledmechs & SASL_MECH_OAUTHBEARER) && conn->oauth_bearer) {
mech = SASL_MECH_STRING_OAUTHBEARER;
state1 = SASL_OAUTH2;
state2 = SASL_OAUTH2_RESP;
sasl->authused = SASL_MECH_OAUTHBEARER;
if(force_ir || data->set.sasl_ir)
result = Curl_auth_create_oauth_bearer_message(data, conn->user,
conn->host.name,
conn->port,
conn->oauth_bearer,
&resp, &len);
}
else if((enabledmechs & SASL_MECH_XOAUTH2) && conn->oauth_bearer) {
mech = SASL_MECH_STRING_XOAUTH2;
state1 = SASL_OAUTH2;
sasl->authused = SASL_MECH_XOAUTH2;
if(force_ir || data->set.sasl_ir)
result = Curl_auth_create_oauth_bearer_message(data, conn->user,
NULL, 0,
conn->oauth_bearer,
&resp, &len);
}
else if(enabledmechs & SASL_MECH_LOGIN) {
mech = SASL_MECH_STRING_LOGIN;
state1 = SASL_LOGIN;
state2 = SASL_LOGIN_PASSWD;
sasl->authused = SASL_MECH_LOGIN;
if(force_ir || data->set.sasl_ir)
result = Curl_auth_create_login_message(data, conn->user, &resp, &len);
}
else if(enabledmechs & SASL_MECH_PLAIN) {
mech = SASL_MECH_STRING_PLAIN;
state1 = SASL_PLAIN;
sasl->authused = SASL_MECH_PLAIN;
if(force_ir || data->set.sasl_ir)
result = Curl_auth_create_plain_message(data, conn->user, conn->passwd,
&resp, &len);
}
}
if(!result && mech) {
if(resp && sasl->params->maxirlen &&
strlen(mech) + len > sasl->params->maxirlen) {
free(resp);
resp = NULL;
}
result = sasl->params->sendauth(conn, mech, resp);
if(!result) {
*progress = SASL_INPROGRESS;
state(sasl, conn, resp ? state2 : state1);
}
}
free(resp);
return result;
}
/*
* Curl_sasl_continue()
*
* Continue the authentication.
*/
CURLcode Curl_sasl_continue(struct SASL *sasl, struct connectdata *conn,
int code, saslprogress *progress)
{
CURLcode result = CURLE_OK;
struct SessionHandle *data = conn->data;
saslstate newstate = SASL_FINAL;
char *resp = NULL;
#if !defined(CURL_DISABLE_CRYPTO_AUTH)
char *serverdata;
char *chlg = NULL;
size_t chlglen = 0;
#endif
size_t len = 0;
*progress = SASL_INPROGRESS;
if(sasl->state == SASL_FINAL) {
if(code != sasl->params->finalcode)
result = CURLE_LOGIN_DENIED;
*progress = SASL_DONE;
state(sasl, conn, SASL_STOP);
return result;
}
if(sasl->state != SASL_CANCEL && sasl->state != SASL_OAUTH2_RESP &&
code != sasl->params->contcode) {
*progress = SASL_DONE;
state(sasl, conn, SASL_STOP);
return CURLE_LOGIN_DENIED;
}
switch(sasl->state) {
case SASL_STOP:
*progress = SASL_DONE;
return result;
case SASL_PLAIN:
result = Curl_auth_create_plain_message(data, conn->user, conn->passwd,
&resp,
&len);
break;
case SASL_LOGIN:
result = Curl_auth_create_login_message(data, conn->user, &resp, &len);
newstate = SASL_LOGIN_PASSWD;
break;
case SASL_LOGIN_PASSWD:
result = Curl_auth_create_login_message(data, conn->passwd, &resp, &len);
break;
case SASL_EXTERNAL:
result = Curl_auth_create_external_message(data, conn->user, &resp, &len);
break;
#ifndef CURL_DISABLE_CRYPTO_AUTH
case SASL_CRAMMD5:
sasl->params->getmessage(data->state.buffer, &serverdata);
result = Curl_auth_decode_cram_md5_message(serverdata, &chlg, &chlglen);
if(!result)
result = Curl_auth_create_cram_md5_message(data, chlg, conn->user,
conn->passwd, &resp, &len);
free(chlg);
break;
case SASL_DIGESTMD5:
sasl->params->getmessage(data->state.buffer, &serverdata);
result = Curl_auth_create_digest_md5_message(data, serverdata,
conn->user, conn->passwd,
sasl->params->service,
&resp, &len);
newstate = SASL_DIGESTMD5_RESP;
break;
case SASL_DIGESTMD5_RESP:
resp = strdup("");
if(!resp)
result = CURLE_OUT_OF_MEMORY;
break;
#endif
#ifdef USE_NTLM
case SASL_NTLM:
/* Create the type-1 message */
result = Curl_auth_create_ntlm_type1_message(conn->user, conn->passwd,
&conn->ntlm, &resp, &len);
newstate = SASL_NTLM_TYPE2MSG;
break;
case SASL_NTLM_TYPE2MSG:
/* Decode the type-2 message */
sasl->params->getmessage(data->state.buffer, &serverdata);
result = Curl_auth_decode_ntlm_type2_message(data, serverdata,
&conn->ntlm);
if(!result)
result = Curl_auth_create_ntlm_type3_message(data, conn->user,
conn->passwd, &conn->ntlm,
&resp, &len);
break;
#endif
#if defined(USE_KERBEROS5)
case SASL_GSSAPI:
result = Curl_auth_create_gssapi_user_message(data, conn->user,
conn->passwd,
sasl->params->service,
data->easy_conn->host.name,
sasl->mutual_auth, NULL,
&conn->krb5,
&resp, &len);
newstate = SASL_GSSAPI_TOKEN;
break;
case SASL_GSSAPI_TOKEN:
sasl->params->getmessage(data->state.buffer, &serverdata);
if(sasl->mutual_auth) {
/* Decode the user token challenge and create the optional response
message */
result = Curl_auth_create_gssapi_user_message(data, NULL, NULL,
NULL, NULL,
sasl->mutual_auth,
serverdata, &conn->krb5,
&resp, &len);
newstate = SASL_GSSAPI_NO_DATA;
}
else
/* Decode the security challenge and create the response message */
result = Curl_auth_create_gssapi_security_message(data, serverdata,
&conn->krb5,
&resp, &len);
break;
case SASL_GSSAPI_NO_DATA:
sasl->params->getmessage(data->state.buffer, &serverdata);
/* Decode the security challenge and create the response message */
result = Curl_auth_create_gssapi_security_message(data, serverdata,
&conn->krb5,
&resp, &len);
break;
#endif
case SASL_OAUTH2:
/* Create the authorisation message */
if(sasl->authused == SASL_MECH_OAUTHBEARER) {
result = Curl_auth_create_oauth_bearer_message(data, conn->user,
conn->host.name,
conn->port,
conn->oauth_bearer,
&resp, &len);
/* Failures maybe sent by the server as continuations for OAUTHBEARER */
newstate = SASL_OAUTH2_RESP;
}
else
result = Curl_auth_create_oauth_bearer_message(data, conn->user,
NULL, 0,
conn->oauth_bearer,
&resp, &len);
break;
case SASL_OAUTH2_RESP:
/* The continuation is optional so check the response code */
if(code == sasl->params->finalcode) {
/* Final response was received so we are done */
*progress = SASL_DONE;
state(sasl, conn, SASL_STOP);
return result;
}
else if(code == sasl->params->contcode) {
/* Acknowledge the continuation by sending a 0x01 response base64
encoded */
resp = strdup("AQ==");
if(!resp)
result = CURLE_OUT_OF_MEMORY;
break;
}
else {
*progress = SASL_DONE;
state(sasl, conn, SASL_STOP);
return CURLE_LOGIN_DENIED;
}
case SASL_CANCEL:
/* Remove the offending mechanism from the supported list */
sasl->authmechs ^= sasl->authused;
/* Start an alternative SASL authentication */
result = Curl_sasl_start(sasl, conn, sasl->force_ir, progress);
newstate = sasl->state; /* Use state from Curl_sasl_start() */
break;
default:
failf(data, "Unsupported SASL authentication mechanism");
result = CURLE_UNSUPPORTED_PROTOCOL; /* Should not happen */
break;
}
switch(result) {
case CURLE_BAD_CONTENT_ENCODING:
/* Cancel dialog */
result = sasl->params->sendcont(conn, "*");
newstate = SASL_CANCEL;
break;
case CURLE_OK:
if(resp)
result = sasl->params->sendcont(conn, resp);
break;
default:
newstate = SASL_STOP; /* Stop on error */
*progress = SASL_DONE;
break;
}
free(resp);
state(sasl, conn, newstate);
return result;
}
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