263 lines
6.6 KiB
C
263 lines
6.6 KiB
C
/*
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* Copyright (c) 1997 - 2005 Kungliga Tekniska Högskolan
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* (Royal Institute of Technology, Stockholm, Sweden).
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include "krb5_locl.h"
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#include <dirent.h>
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RCSID("$Id: kuserok.c 16048 2005-09-09 10:33:33Z lha $");
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/* see if principal is mentioned in the filename access file, return
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TRUE (in result) if so, FALSE otherwise */
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static krb5_error_code
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check_one_file(krb5_context context,
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const char *filename,
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struct passwd *pwd,
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krb5_principal principal,
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krb5_boolean *result)
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{
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FILE *f;
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char buf[BUFSIZ];
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krb5_error_code ret;
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struct stat st;
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*result = FALSE;
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f = fopen (filename, "r");
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if (f == NULL)
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return errno;
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/* check type and mode of file */
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if (fstat(fileno(f), &st) != 0) {
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fclose (f);
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return errno;
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}
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if (S_ISDIR(st.st_mode)) {
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fclose (f);
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return EISDIR;
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}
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if (st.st_uid != pwd->pw_uid && st.st_uid != 0) {
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fclose (f);
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return EACCES;
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}
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if ((st.st_mode & (S_IWGRP | S_IWOTH)) != 0) {
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fclose (f);
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return EACCES;
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}
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while (fgets (buf, sizeof(buf), f) != NULL) {
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krb5_principal tmp;
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char *newline = buf + strcspn(buf, "\n");
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if(*newline != '\n') {
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int c;
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c = fgetc(f);
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if(c != EOF) {
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while(c != EOF && c != '\n')
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c = fgetc(f);
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/* line was too long, so ignore it */
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continue;
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}
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}
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*newline = '\0';
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ret = krb5_parse_name (context, buf, &tmp);
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if (ret)
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continue;
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*result = krb5_principal_compare (context, principal, tmp);
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krb5_free_principal (context, tmp);
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if (*result) {
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fclose (f);
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return 0;
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}
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}
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fclose (f);
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return 0;
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}
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static krb5_error_code
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check_directory(krb5_context context,
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const char *dirname,
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struct passwd *pwd,
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krb5_principal principal,
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krb5_boolean *result)
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{
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DIR *d;
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struct dirent *dent;
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char filename[MAXPATHLEN];
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krb5_error_code ret = 0;
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struct stat st;
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*result = FALSE;
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if(lstat(dirname, &st) < 0)
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return errno;
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if (!S_ISDIR(st.st_mode))
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return ENOTDIR;
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if (st.st_uid != pwd->pw_uid && st.st_uid != 0)
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return EACCES;
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if ((st.st_mode & (S_IWGRP | S_IWOTH)) != 0)
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return EACCES;
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if((d = opendir(dirname)) == NULL)
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return errno;
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#ifdef HAVE_DIRFD
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{
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int fd;
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struct stat st2;
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fd = dirfd(d);
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if(fstat(fd, &st2) < 0) {
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closedir(d);
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return errno;
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}
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if(st.st_dev != st2.st_dev || st.st_ino != st2.st_ino) {
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closedir(d);
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return EACCES;
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}
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}
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#endif
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while((dent = readdir(d)) != NULL) {
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if(strcmp(dent->d_name, ".") == 0 ||
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strcmp(dent->d_name, "..") == 0 ||
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dent->d_name[0] == '#' || /* emacs autosave */
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dent->d_name[strlen(dent->d_name) - 1] == '~') /* emacs backup */
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continue;
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snprintf(filename, sizeof(filename), "%s/%s", dirname, dent->d_name);
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ret = check_one_file(context, filename, pwd, principal, result);
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if(ret == 0 && *result == TRUE)
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break;
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ret = 0; /* don't propagate errors upstream */
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}
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closedir(d);
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return ret;
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}
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static krb5_boolean
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match_local_principals(krb5_context context,
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krb5_principal principal,
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const char *luser)
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{
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krb5_error_code ret;
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krb5_realm *realms, *r;
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krb5_boolean result = FALSE;
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/* multi-component principals can never match */
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if(krb5_principal_get_comp_string(context, principal, 1) != NULL)
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return FALSE;
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ret = krb5_get_default_realms (context, &realms);
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if (ret)
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return FALSE;
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for (r = realms; *r != NULL; ++r) {
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if(strcmp(krb5_principal_get_realm(context, principal),
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*r) != 0)
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continue;
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if(strcmp(krb5_principal_get_comp_string(context, principal, 0),
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luser) == 0) {
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result = TRUE;
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break;
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}
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}
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krb5_free_host_realm (context, realms);
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return result;
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}
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/**
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* Return TRUE iff `principal' is allowed to login as `luser'.
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*/
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krb5_boolean KRB5_LIB_FUNCTION
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krb5_kuserok (krb5_context context,
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krb5_principal principal,
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const char *luser)
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{
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char *buf;
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size_t buflen;
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struct passwd *pwd;
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krb5_error_code ret;
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krb5_boolean result = FALSE;
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krb5_boolean found_file = FALSE;
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#ifdef POSIX_GETPWNAM_R
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char pwbuf[2048];
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struct passwd pw;
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if(getpwnam_r(luser, &pw, pwbuf, sizeof(pwbuf), &pwd) != 0)
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return FALSE;
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#else
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pwd = getpwnam (luser);
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#endif
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if (pwd == NULL)
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return FALSE;
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#define KLOGIN "/.k5login"
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buflen = strlen(pwd->pw_dir) + sizeof(KLOGIN) + 2; /* 2 for .d */
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buf = malloc(buflen);
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if(buf == NULL)
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return FALSE;
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/* check user's ~/.k5login */
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strlcpy(buf, pwd->pw_dir, buflen);
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strlcat(buf, KLOGIN, buflen);
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ret = check_one_file(context, buf, pwd, principal, &result);
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if(ret == 0 && result == TRUE) {
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free(buf);
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return TRUE;
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}
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if(ret != ENOENT)
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found_file = TRUE;
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strlcat(buf, ".d", buflen);
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ret = check_directory(context, buf, pwd, principal, &result);
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free(buf);
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if(ret == 0 && result == TRUE)
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return TRUE;
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if(ret != ENOENT && ret != ENOTDIR)
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found_file = TRUE;
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/* finally if no files exist, allow all principals matching
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<localuser>@<LOCALREALM> */
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if(found_file == FALSE)
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return match_local_principals(context, principal, luser);
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return FALSE;
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}
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