OpenBSD-4.6/kerberosV/src/lib/krb5/kuserok.c
/*
* Copyright (c) 1997 - 2005 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.
*/
#include "krb5_locl.h"
#include <dirent.h>
RCSID("$KTH: kuserok.c,v 1.13.2.1 2005/09/09 10:47:46 lha Exp $");
/* see if principal is mentioned in the filename access file, return
TRUE (in result) if so, FALSE otherwise */
static krb5_error_code
check_one_file(krb5_context context,
const char *filename,
struct passwd *pwd,
krb5_principal principal,
krb5_boolean *result)
{
FILE *f;
char buf[BUFSIZ];
krb5_error_code ret;
struct stat st;
*result = FALSE;
f = fopen (filename, "r");
if (f == NULL)
return errno;
/* check type and mode of file */
if (fstat(fileno(f), &st) != 0) {
fclose (f);
return errno;
}
if (S_ISDIR(st.st_mode)) {
fclose (f);
return EISDIR;
}
if (st.st_uid != pwd->pw_uid && st.st_uid != 0) {
fclose (f);
return EACCES;
}
if ((st.st_mode & (S_IWGRP | S_IWOTH)) != 0) {
fclose (f);
return EACCES;
}
while (fgets (buf, sizeof(buf), f) != NULL) {
krb5_principal tmp;
char *newline = buf + strcspn(buf, "\n");
if(*newline != '\n') {
int c;
c = fgetc(f);
if(c != EOF) {
while(c != EOF && c != '\n')
c = fgetc(f);
/* line was too long, so ignore it */
continue;
}
}
*newline = '\0';
ret = krb5_parse_name (context, buf, &tmp);
if (ret)
continue;
*result = krb5_principal_compare (context, principal, tmp);
krb5_free_principal (context, tmp);
if (*result) {
fclose (f);
return 0;
}
}
fclose (f);
return 0;
}
static krb5_error_code
check_directory(krb5_context context,
const char *dirname,
struct passwd *pwd,
krb5_principal principal,
krb5_boolean *result)
{
DIR *d;
struct dirent *dent;
char filename[MAXPATHLEN];
krb5_error_code ret = 0;
struct stat st;
*result = FALSE;
if(lstat(dirname, &st) < 0)
return errno;
if (!S_ISDIR(st.st_mode))
return ENOTDIR;
if (st.st_uid != pwd->pw_uid && st.st_uid != 0)
return EACCES;
if ((st.st_mode & (S_IWGRP | S_IWOTH)) != 0)
return EACCES;
if((d = opendir(dirname)) == NULL)
return errno;
#ifdef HAVE_DIRFD
{
int fd;
struct stat st2;
fd = dirfd(d);
if(fstat(fd, &st2) < 0) {
closedir(d);
return errno;
}
if(st.st_dev != st2.st_dev || st.st_ino != st2.st_ino) {
closedir(d);
return EACCES;
}
}
#endif
while((dent = readdir(d)) != NULL) {
if(strcmp(dent->d_name, ".") == 0 ||
strcmp(dent->d_name, "..") == 0 ||
dent->d_name[0] == '#' || /* emacs autosave */
dent->d_name[strlen(dent->d_name) - 1] == '~') /* emacs backup */
continue;
snprintf(filename, sizeof(filename), "%s/%s", dirname, dent->d_name);
ret = check_one_file(context, filename, pwd, principal, result);
if(ret == 0 && *result == TRUE)
break;
ret = 0; /* don't propagate errors upstream */
}
closedir(d);
return ret;
}
static krb5_boolean
match_local_principals(krb5_context context,
krb5_principal principal,
const char *luser)
{
krb5_error_code ret;
krb5_realm *realms, *r;
krb5_boolean result = FALSE;
/* multi-component principals can never match */
if(krb5_principal_get_comp_string(context, principal, 1) != NULL)
return FALSE;
ret = krb5_get_default_realms (context, &realms);
if (ret)
return FALSE;
for (r = realms; *r != NULL; ++r) {
if(strcmp(krb5_principal_get_realm(context, principal),
*r) != 0)
continue;
if(strcmp(krb5_principal_get_comp_string(context, principal, 0),
luser) == 0) {
result = TRUE;
break;
}
}
krb5_free_host_realm (context, realms);
return result;
}
/**
* Return TRUE iff `principal' is allowed to login as `luser'.
*/
krb5_boolean KRB5_LIB_FUNCTION
krb5_kuserok (krb5_context context,
krb5_principal principal,
const char *luser)
{
char *buf;
size_t buflen;
struct passwd *pwd;
krb5_error_code ret;
krb5_boolean result = FALSE;
krb5_boolean found_file = FALSE;
#ifdef POSIX_GETPWNAM_R
char pwbuf[2048];
struct passwd pw;
if(getpwnam_r(luser, &pw, pwbuf, sizeof(pwbuf), &pwd) != 0)
return FALSE;
#else
pwd = getpwnam (luser);
#endif
if (pwd == NULL)
return FALSE;
#define KLOGIN "/.k5login"
buflen = strlen(pwd->pw_dir) + sizeof(KLOGIN) + 2; /* 2 for .d */
buf = malloc(buflen);
if(buf == NULL)
return FALSE;
/* check user's ~/.k5login */
strlcpy(buf, pwd->pw_dir, buflen);
strlcat(buf, KLOGIN, buflen);
ret = check_one_file(context, buf, pwd, principal, &result);
if(ret == 0 && result == TRUE) {
free(buf);
return TRUE;
}
if(ret != ENOENT)
found_file = TRUE;
strlcat(buf, ".d", buflen);
ret = check_directory(context, buf, pwd, principal, &result);
free(buf);
if(ret == 0 && result == TRUE)
return TRUE;
if(ret != ENOENT && ret != ENOTDIR)
found_file = TRUE;
/* finally if no files exist, allow all principals matching
<localuser>@<LOCALREALM> */
if(found_file == FALSE)
return match_local_principals(context, principal, luser);
return FALSE;
}