344 lines
8.8 KiB
C
344 lines
8.8 KiB
C
/*
|
|
* Copyright (c) 2019 Kungliga Tekniska Högskolan
|
|
* (Royal Institute of Technology, Stockholm, Sweden).
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
*
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
*
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
*
|
|
* 3. Neither the name of the Institute nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*/
|
|
|
|
/*
|
|
* This plugin authorizes requested certificate SANs and EKUs by checking for
|
|
* existence of files of the form:
|
|
*
|
|
*
|
|
* /<path>/<princ>/<ext>-<value>
|
|
*
|
|
* where <path> is the value of:
|
|
*
|
|
* [kdc] simple_csr_authorizer_directory = PATH
|
|
*
|
|
* <princ> is a requesting client principal name with all characters other than
|
|
* alphanumeric, '-', '_', and non-leading '.' URL-encoded.
|
|
*
|
|
* <ext> is one of:
|
|
*
|
|
* - pkinit (SAN)
|
|
* - xmpp (SAN)
|
|
* - email (SAN)
|
|
* - ms-upn (SAN)
|
|
* - dnsname (SAN)
|
|
* - eku (EKU OID)
|
|
*
|
|
* and <value> is a display form of the SAN or EKU OID, with SANs URL-encoded
|
|
* just like principal names (see above).
|
|
*
|
|
* OIDs are of the form "1.2.3.4.5".
|
|
*
|
|
* Only digitalSignature and nonRepudiation key usage values are permitted.
|
|
*/
|
|
#define _GNU_SOURCE 1
|
|
|
|
#include <sys/types.h>
|
|
#include <sys/stat.h>
|
|
#include <ctype.h>
|
|
#include <errno.h>
|
|
#include <stdlib.h>
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include <unistd.h>
|
|
|
|
#include <roken.h>
|
|
#include <krb5.h>
|
|
#include <hx509.h>
|
|
#include <kdc.h>
|
|
#include <common_plugin.h>
|
|
#include <csr_authorizer_plugin.h>
|
|
|
|
/*
|
|
* string_encode_sz() and string_encode() encode a string to be safe for use as
|
|
* a file name. They function very much like URL encoders, but '~' also gets
|
|
* encoded, and '@', '-', '_', and non-leading '.' do not.
|
|
*
|
|
* A corresponding decoder is not needed.
|
|
*/
|
|
static size_t
|
|
string_encode_sz(const char *in)
|
|
{
|
|
size_t sz = strlen(in);
|
|
int first = 1;
|
|
|
|
while (*in) {
|
|
char c = *(in++);
|
|
|
|
switch (c) {
|
|
case '@':
|
|
case '-':
|
|
case '_':
|
|
break;
|
|
case '.':
|
|
if (first)
|
|
sz += 2;
|
|
break;
|
|
default:
|
|
if (!isalnum(c))
|
|
sz += 2;
|
|
}
|
|
first = 0;
|
|
}
|
|
return sz;
|
|
}
|
|
|
|
static char *
|
|
string_encode(const char *in)
|
|
{
|
|
size_t len = strlen(in);
|
|
size_t sz = string_encode_sz(in);
|
|
size_t i, k;
|
|
char *s;
|
|
int first = 1;
|
|
|
|
if ((s = malloc(sz + 1)) == NULL)
|
|
return NULL;
|
|
s[sz] = '\0';
|
|
|
|
for (i = k = 0; i < len; i++, first = 0) {
|
|
unsigned char c = ((const unsigned char *)in)[i];
|
|
|
|
switch (c) {
|
|
case '@':
|
|
case '-':
|
|
case '_':
|
|
s[k++] = c;
|
|
break;
|
|
case '.':
|
|
if (first) {
|
|
s[k++] = '%';
|
|
s[k++] = "0123456789abcdef"[(c&0xff)>>4];
|
|
s[k++] = "0123456789abcdef"[(c&0x0f)];
|
|
} else {
|
|
s[k++] = c;
|
|
}
|
|
break;
|
|
default:
|
|
if (isalnum(c)) {
|
|
s[k++] = c;
|
|
} else {
|
|
s[k++] = '%';
|
|
s[k++] = "0123456789abcdef"[(c&0xff)>>4];
|
|
s[k++] = "0123456789abcdef"[(c&0x0f)];
|
|
}
|
|
}
|
|
}
|
|
return s;
|
|
}
|
|
|
|
static void
|
|
frees(char **s)
|
|
{
|
|
free(*s);
|
|
*s = NULL;
|
|
}
|
|
|
|
static KRB5_LIB_CALL krb5_error_code
|
|
authorize(void *ctx,
|
|
krb5_context context,
|
|
const char *app,
|
|
hx509_request csr,
|
|
krb5_const_principal client,
|
|
krb5_boolean *result)
|
|
{
|
|
krb5_error_code ret;
|
|
hx509_context hx509ctx = NULL;
|
|
KeyUsage ku;
|
|
const char *d;
|
|
size_t i;
|
|
char *princ = NULL;
|
|
char *s = NULL;
|
|
|
|
if ((d = krb5_config_get_string(context, NULL, app ? app : "kdc",
|
|
"simple_csr_authorizer_directory",
|
|
NULL)) == NULL)
|
|
return KRB5_PLUGIN_NO_HANDLE;
|
|
|
|
if ((ret = hx509_context_init(&hx509ctx)))
|
|
return ret;
|
|
|
|
if ((ret = krb5_unparse_name(context, client, &princ)))
|
|
goto out;
|
|
|
|
s = string_encode(princ);
|
|
free(princ);
|
|
princ = NULL;
|
|
if (s == NULL)
|
|
goto enomem;
|
|
|
|
princ = s;
|
|
s = NULL;
|
|
|
|
for (i = 0; ret == 0; i++) {
|
|
hx509_san_type san_type;
|
|
struct stat st;
|
|
const char *prefix;
|
|
char *san;
|
|
char *p;
|
|
|
|
ret = hx509_request_get_san(csr, i, &san_type, &s);
|
|
if (ret)
|
|
break;
|
|
switch (san_type) {
|
|
case HX509_SAN_TYPE_EMAIL:
|
|
prefix = "email";
|
|
break;
|
|
case HX509_SAN_TYPE_DNSNAME:
|
|
prefix = "dnsname";
|
|
break;
|
|
case HX509_SAN_TYPE_XMPP:
|
|
prefix = "xmpp";
|
|
break;
|
|
case HX509_SAN_TYPE_PKINIT:
|
|
prefix = "pkinit";
|
|
break;
|
|
case HX509_SAN_TYPE_MS_UPN:
|
|
prefix = "ms-upn";
|
|
break;
|
|
default:
|
|
ret = ENOTSUP;
|
|
break;
|
|
}
|
|
if (ret)
|
|
break;
|
|
|
|
if ((san = string_encode(s)) == NULL ||
|
|
asprintf(&p, "%s/%s/%s-%s", d, princ, prefix, san) == -1 ||
|
|
p == NULL) {
|
|
free(san);
|
|
goto enomem;
|
|
}
|
|
ret = stat(p, &st) == -1 ? errno : 0;
|
|
free(san);
|
|
free(p);
|
|
frees(&s);
|
|
if (ret)
|
|
goto skip;
|
|
ret = hx509_request_authorize_san(csr, i);
|
|
}
|
|
frees(&s);
|
|
if (ret == HX509_NO_ITEM)
|
|
ret = 0;
|
|
if (ret)
|
|
goto out;
|
|
|
|
for (i = 0; ret == 0; i++) {
|
|
struct stat st;
|
|
char *p;
|
|
|
|
ret = hx509_request_get_eku(csr, i, &s);
|
|
if (ret)
|
|
break;
|
|
if (asprintf(&p, "%s/%s/eku-%s", d, princ, s) == -1 || p == NULL)
|
|
goto enomem;
|
|
ret = stat(p, &st) == -1 ? errno : 0;
|
|
free(p);
|
|
frees(&s);
|
|
if (ret)
|
|
goto skip;
|
|
ret = hx509_request_authorize_eku(csr, i);
|
|
}
|
|
if (ret == HX509_NO_ITEM)
|
|
ret = 0;
|
|
if (ret)
|
|
goto out;
|
|
|
|
ku = int2KeyUsage(0);
|
|
ku.digitalSignature = 1;
|
|
ku.nonRepudiation = 1;
|
|
hx509_request_authorize_ku(csr, ku);
|
|
|
|
*result = TRUE;
|
|
ret = 0;
|
|
goto out;
|
|
|
|
skip:
|
|
/* Allow another plugin to get a crack at this */
|
|
ret = KRB5_PLUGIN_NO_HANDLE;
|
|
goto out;
|
|
|
|
enomem:
|
|
ret = krb5_enomem(context);
|
|
goto out;
|
|
|
|
out:
|
|
hx509_context_free(&hx509ctx);
|
|
free(princ);
|
|
free(s);
|
|
return ret;
|
|
}
|
|
|
|
static KRB5_LIB_CALL krb5_error_code
|
|
simple_csr_authorizer_init(krb5_context context, void **c)
|
|
{
|
|
*c = NULL;
|
|
return 0;
|
|
}
|
|
|
|
static KRB5_LIB_CALL void
|
|
simple_csr_authorizer_fini(void *c)
|
|
{
|
|
}
|
|
|
|
static krb5plugin_csr_authorizer_ftable plug_desc =
|
|
{ 1, simple_csr_authorizer_init, simple_csr_authorizer_fini, authorize };
|
|
|
|
static krb5plugin_csr_authorizer_ftable *plugs[] = { &plug_desc };
|
|
|
|
static uintptr_t
|
|
simple_csr_authorizer_get_instance(const char *libname)
|
|
{
|
|
if (strcmp(libname, "krb5") == 0)
|
|
return krb5_get_instance(libname);
|
|
if (strcmp(libname, "kdc") == 0)
|
|
return kdc_get_instance(libname);
|
|
if (strcmp(libname, "hx509") == 0)
|
|
return hx509_get_instance(libname);
|
|
return 0;
|
|
}
|
|
|
|
krb5_plugin_load_ft kdc_csr_authorizer_plugin_load;
|
|
|
|
krb5_error_code KRB5_CALLCONV
|
|
kdc_csr_authorizer_plugin_load(heim_pcontext context,
|
|
krb5_get_instance_func_t *get_instance,
|
|
size_t *num_plugins,
|
|
krb5_plugin_common_ftable_cp **plugins)
|
|
{
|
|
*get_instance = simple_csr_authorizer_get_instance;
|
|
*num_plugins = sizeof(plugs) / sizeof(plugs[0]);
|
|
*plugins = (krb5_plugin_common_ftable_cp *)plugs;
|
|
return 0;
|
|
}
|