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/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* lib/krb5/ccache/ccselect_k5identity.c - k5identity ccselect module */
/*
* Copyright (C) 2011 by the Massachusetts Institute of Technology.
* All rights reserved.
*
* Export of this software from the United States of America may
* require a specific license from the United States Government.
* It is the responsibility of any person or organization contemplating
* export to obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of M.I.T. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. Furthermore if you modify this software you must label
* your software as modified software and not distribute it in such a
* fashion that it might be confused with the original M.I.T. software.
* M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*/
#include "k5-int.h"
#include "cc-int.h"
#include <krb5/ccselect_plugin.h>
#include <ctype.h>
#ifndef _WIN32
#include <pwd.h>
static krb5_error_code
k5identity_init(krb5_context context, krb5_ccselect_moddata *data_out,
int *priority_out)
{
*data_out = NULL;
*priority_out = KRB5_CCSELECT_PRIORITY_AUTHORITATIVE;
return 0;
}
/* Match data (folded to lowercase if fold_case is set) against pattern. */
static krb5_boolean
fnmatch_data(const char *pattern, krb5_data *data, krb5_boolean fold_case)
{
krb5_error_code ret;
char *str, *p;
int res;
str = k5memdup0(data->data, data->length, &ret);
if (str == NULL)
return FALSE;
if (fold_case) {
for (p = str; *p != '\0'; p++) {
if (isupper((unsigned char)*p))
*p = tolower((unsigned char)*p);
}
}
res = fnmatch(pattern, str, 0);
free(str);
return (res == 0);
}
/* Return true if server satisfies the constraint given by name and value. */
static krb5_boolean
check_constraint(krb5_context context, const char *name, const char *value,
krb5_principal server)
{
if (strcmp(name, "realm") == 0) {
return fnmatch_data(value, &server->realm, FALSE);
} else if (strcmp(name, "service") == 0) {
return (server->type == KRB5_NT_SRV_HST && server->length >= 2 &&
fnmatch_data(value, &server->data[0], FALSE));
} else if (strcmp(name, "host") == 0) {
return (server->type == KRB5_NT_SRV_HST && server->length >= 2 &&
fnmatch_data(value, &server->data[1], TRUE));
}
/* Assume unrecognized constraints are critical. */
return FALSE;
}
/*
* If line begins with a valid principal and server matches the constraints
* listed afterwards, set *princ_out to the client principal described in line
* and return true. Otherwise return false. May destructively affect line.
*/
static krb5_boolean
parse_line(krb5_context context, char *line, krb5_principal server,
krb5_principal *princ_out)
{
const char *whitespace = " \t\r\n";
char *princ, *princ_end, *field, *field_end, *sep;
*princ_out = NULL;
/* Find the bounds of the principal. */
princ = line + strspn(line, whitespace);
if (*princ == '#')
return FALSE;
princ_end = princ + strcspn(princ, whitespace);
if (princ_end == princ)
return FALSE;
/* Check all constraints. */
field = princ_end + strspn(princ_end, whitespace);
while (*field != '\0') {
field_end = field + strcspn(field, whitespace);
if (*field_end != '\0')
*field_end++ = '\0';
sep = strchr(field, '=');
if (sep == NULL) /* Malformed line. */
return FALSE;
*sep = '\0';
if (!check_constraint(context, field, sep + 1, server))
return FALSE;
field = field_end + strspn(field_end, whitespace);
}
*princ_end = '\0';
return (krb5_parse_name(context, princ, princ_out) == 0);
}
/* Determine the current user's homedir. Allow HOME to override the result for
* non-secure profiles; otherwise, use the euid's homedir from passwd. */
static char *
get_homedir(krb5_context context)
{
const char *homedir = NULL;
char pwbuf[BUFSIZ];
struct passwd pwx, *pwd;
if (!context->profile_secure)
homedir = getenv("HOME");
if (homedir == NULL) {
if (k5_getpwuid_r(geteuid(), &pwx, pwbuf, sizeof(pwbuf), &pwd) != 0)
return NULL;
homedir = pwd->pw_dir;
}
return strdup(homedir);
}
static krb5_error_code
k5identity_choose(krb5_context context, krb5_ccselect_moddata data,
krb5_principal server, krb5_ccache *cache_out,
krb5_principal *princ_out)
{
krb5_error_code ret;
krb5_principal princ = NULL;
char *filename, *homedir;
FILE *fp;
char buf[256];
*cache_out = NULL;
*princ_out = NULL;
/* Open the .k5identity file. */
homedir = get_homedir(context);
if (homedir == NULL)
return KRB5_PLUGIN_NO_HANDLE;
ret = k5_path_join(homedir, ".k5identity", &filename);
free(homedir);
if (ret)
return ret;
fp = fopen(filename, "r");
free(filename);
if (fp == NULL)
return KRB5_PLUGIN_NO_HANDLE;
/* Look for a line with constraints matched by server. */
while (fgets(buf, sizeof(buf), fp) != NULL) {
if (parse_line(context, buf, server, &princ))
break;
}
fclose(fp);
if (princ == NULL)
return KRB5_PLUGIN_NO_HANDLE;
/* Look for a ccache with the appropriate client principal. If we don't
* find out, set *princ_out to indicate the desired client principal. */
ret = krb5_cc_cache_match(context, princ, cache_out);
if (ret == 0 || ret == KRB5_CC_NOTFOUND)
*princ_out = princ;
else
krb5_free_principal(context, princ);
return ret;
}
krb5_error_code
ccselect_k5identity_initvt(krb5_context context, int maj_ver, int min_ver,
krb5_plugin_vtable vtable)
{
krb5_ccselect_vtable vt;
if (maj_ver != 1)
return KRB5_PLUGIN_VER_NOTSUPP;
vt = (krb5_ccselect_vtable)vtable;
vt->name = "k5identity";
vt->init = k5identity_init;
vt->choose = k5identity_choose;
return 0;
}
#endif /* not _WIN32 */
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