crypto/dist/heimdal/lib/krb5/kuserok.c

   1 /*
   2  * Copyright (c) 1997 - 2005 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include "krb5_locl.h"
  35 #include <dirent.h>
  36
  37 __RCSID("$Heimdal: kuserok.c 16048 2005-09-09 10:33:33Z lha $"
  38         "$NetBSD$");
  39
  40 /* see if principal is mentioned in the filename access file, return
  41    TRUE (in result) if so, FALSE otherwise */
  42
  43 static krb5_error_code
  44 check_one_file(krb5_context context,
  45                const char *filename,
  46                struct passwd *pwd,
  47                krb5_principal principal,
  48                krb5_boolean *result)
  49 {
  50     FILE *f;
  51     char buf[BUFSIZ];
  52     krb5_error_code ret;
  53     struct stat st;
  54
  55     *result = FALSE;
  56
  57     f = fopen (filename, "r");
  58     if (f == NULL)
  59         return errno;
  60
  61     /* check type and mode of file */
  62     if (fstat(fileno(f), &st) != 0) {
  63         fclose (f);
  64         return errno;
  65     }
  66     if (S_ISDIR(st.st_mode)) {
  67         fclose (f);
  68         return EISDIR;
  69     }
  70     if (st.st_uid != pwd->pw_uid && st.st_uid != 0) {
  71         fclose (f);
  72         return EACCES;
  73     }
  74     if ((st.st_mode & (S_IWGRP | S_IWOTH)) != 0) {
  75         fclose (f);
  76         return EACCES;
  77     }
  78
  79     while (fgets (buf, sizeof(buf), f) != NULL) {
  80         krb5_principal tmp;
  81         char *newline = buf + strcspn(buf, "\n");
  82
  83         if(*newline != '\n') {
  84             int c;
  85             c = fgetc(f);
  86             if(c != EOF) {
  87                 while(c != EOF && c != '\n')
  88                     c = fgetc(f);
  89                 /* line was too long, so ignore it */
  90                 continue;
  91             }
  92         }
  93         *newline = '\0';
  94         ret = krb5_parse_name (context, buf, &tmp);
  95         if (ret)
  96             continue;
  97         *result = krb5_principal_compare (context, principal, tmp);
  98         krb5_free_principal (context, tmp);
  99         if (*result) {
 100             fclose (f);
 101             return 0;
 102         }
 103     }
 104     fclose (f);
 105     return 0;
 106 }
 107
 108 static krb5_error_code
 109 check_directory(krb5_context context,
 110                 const char *dirname,
 111                 struct passwd *pwd,
 112                 krb5_principal principal,
 113                 krb5_boolean *result)
 114 {
 115     DIR *d;
 116     struct dirent *dent;
 117     char filename[MAXPATHLEN];
 118     krb5_error_code ret = 0;
 119     struct stat st;
 120
 121     *result = FALSE;
 122
 123     if(lstat(dirname, &st) < 0)
 124         return errno;
 125
 126     if (!S_ISDIR(st.st_mode))
 127         return ENOTDIR;
 128
 129     if (st.st_uid != pwd->pw_uid && st.st_uid != 0)
 130         return EACCES;
 131     if ((st.st_mode & (S_IWGRP | S_IWOTH)) != 0)
 132         return EACCES;
 133
 134     if((d = opendir(dirname)) == NULL)
 135         return errno;
 136
 137 #ifdef HAVE_DIRFD
 138     {
 139         int fd;
 140         struct stat st2;
 141
 142         fd = dirfd(d);
 143         if(fstat(fd, &st2) < 0) {
 144             closedir(d);
 145             return errno;
 146         }
 147         if(st.st_dev != st2.st_dev || st.st_ino != st2.st_ino) {
 148             closedir(d);
 149             return EACCES;
 150         }
 151     }
 152 #endif
 153
 154     while((dent = readdir(d)) != NULL) {
 155         if(strcmp(dent->d_name, ".") == 0 ||
 156            strcmp(dent->d_name, "..") == 0 ||
 157            dent->d_name[0] == '#' ||                      /* emacs autosave */
 158            dent->d_name[strlen(dent->d_name) - 1] == '~') /* emacs backup */
 159             continue;
 160         snprintf(filename, sizeof(filename), "%s/%s", dirname, dent->d_name);
 161         ret = check_one_file(context, filename, pwd, principal, result);
 162         if(ret == 0 && *result == TRUE)
 163             break;
 164         ret = 0; /* don't propagate errors upstream */
 165     }
 166     closedir(d);
 167     return ret;
 168 }
 169
 170 static krb5_boolean
 171 match_local_principals(krb5_context context,
 172                        krb5_principal principal,
 173                        const char *luser)
 174 {
 175     krb5_error_code ret;
 176     krb5_realm *realms, *r;
 177     krb5_boolean result = FALSE;
 178
 179     /* multi-component principals can never match */
 180     if(krb5_principal_get_comp_string(context, principal, 1) != NULL)
 181         return FALSE;
 182
 183     ret = krb5_get_default_realms (context, &realms);
 184     if (ret)
 185         return FALSE;
 186
 187     for (r = realms; *r != NULL; ++r) {
 188         if(strcmp(krb5_principal_get_realm(context, principal),
 189                   *r) != 0)
 190             continue;
 191         if(strcmp(krb5_principal_get_comp_string(context, principal, 0),
 192                   luser) == 0) {
 193             result = TRUE;
 194             break;
 195         }
 196     }
 197     krb5_free_host_realm (context, realms);
 198     return result;
 199 }
 200
 201 /**
 202  * Return TRUE iff `principal' is allowed to login as `luser'.
 203  */
 204
 205 krb5_boolean KRB5_LIB_FUNCTION
 206 krb5_kuserok (krb5_context context,
 207               krb5_principal principal,
 208               const char *luser)
 209 {
 210     char *buf;
 211     size_t buflen;
 212     struct passwd *pwd;
 213     krb5_error_code ret;
 214     krb5_boolean result = FALSE;
 215
 216     krb5_boolean found_file = FALSE;
 217
 218 #ifdef POSIX_GETPWNAM_R
 219     char pwbuf[2048];
 220     struct passwd pw;
 221
 222     if(getpwnam_r(luser, &pw, pwbuf, sizeof(pwbuf), &pwd) != 0)
 223         return FALSE;
 224 #else
 225     pwd = getpwnam (luser);
 226 #endif
 227     if (pwd == NULL)
 228         return FALSE;
 229
 230 #define KLOGIN "/.k5login"
 231     buflen = strlen(pwd->pw_dir) + sizeof(KLOGIN) + 2; /* 2 for .d */
 232     buf = malloc(buflen);
 233     if(buf == NULL)
 234         return FALSE;
 235     /* check user's ~/.k5login */
 236     strlcpy(buf, pwd->pw_dir, buflen);
 237     strlcat(buf, KLOGIN, buflen);
 238     ret = check_one_file(context, buf, pwd, principal, &result);
 239
 240     if(ret == 0 && result == TRUE) {
 241         free(buf);
 242         return TRUE;
 243     }
 244
 245     if(ret != ENOENT)
 246         found_file = TRUE;
 247
 248     strlcat(buf, ".d", buflen);
 249     ret = check_directory(context, buf, pwd, principal, &result);
 250     free(buf);
 251     if(ret == 0 && result == TRUE)
 252         return TRUE;
 253
 254     if(ret != ENOENT && ret != ENOTDIR)
 255         found_file = TRUE;
 256
 257     /* finally if no files exist, allow all principals matching
 258        <localuser>@<LOCALREALM> */
 259     if(found_file == FALSE)
 260         return match_local_principals(context, principal, luser);
 261
 262     return FALSE;
 263 }