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

   1 /*      $NetBSD: kuserok.c,v 1.1.1.2 2014/04/24 12:45:50 pettai Exp $   */
   2
   3 /*
   4  * Copyright (c) 1997 - 2005 Kungliga Tekniska Högskolan
   5  * (Royal Institute of Technology, Stockholm, Sweden).
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  *
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * 3. Neither the name of the Institute nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  */
  35
  36 #include "krb5_locl.h"
  37 #include <dirent.h>
  38
  39 #ifndef _WIN32
  40
  41 /* see if principal is mentioned in the filename access file, return
  42    TRUE (in result) if so, FALSE otherwise */
  43
  44 static krb5_error_code
  45 check_one_file(krb5_context context,
  46                const char *filename,
  47                struct passwd *pwd,
  48                krb5_principal principal,
  49                krb5_boolean *result)
  50 {
  51     FILE *f;
  52     char buf[BUFSIZ];
  53     krb5_error_code ret;
  54     struct stat st;
  55
  56     *result = FALSE;
  57
  58     f = fopen (filename, "r");
  59     if (f == NULL)
  60         return errno;
  61     rk_cloexec_file(f);
  62
  63     /* check type and mode of file */
  64     if (fstat(fileno(f), &st) != 0) {
  65         fclose (f);
  66         return errno;
  67     }
  68     if (S_ISDIR(st.st_mode)) {
  69         fclose (f);
  70         return EISDIR;
  71     }
  72     if (st.st_uid != pwd->pw_uid && st.st_uid != 0) {
  73         fclose (f);
  74         return EACCES;
  75     }
  76     if ((st.st_mode & (S_IWGRP | S_IWOTH)) != 0) {
  77         fclose (f);
  78         return EACCES;
  79     }
  80
  81     while (fgets (buf, sizeof(buf), f) != NULL) {
  82         krb5_principal tmp;
  83         char *newline = buf + strcspn(buf, "\n");
  84
  85         if(*newline != '\n') {
  86             int c;
  87             c = fgetc(f);
  88             if(c != EOF) {
  89                 while(c != EOF && c != '\n')
  90                     c = fgetc(f);
  91                 /* line was too long, so ignore it */
  92                 continue;
  93             }
  94         }
  95         *newline = '\0';
  96         ret = krb5_parse_name (context, buf, &tmp);
  97         if (ret)
  98             continue;
  99         *result = krb5_principal_compare (context, principal, tmp);
 100         krb5_free_principal (context, tmp);
 101         if (*result) {
 102             fclose (f);
 103             return 0;
 104         }
 105     }
 106     fclose (f);
 107     return 0;
 108 }
 109
 110 static krb5_error_code
 111 check_directory(krb5_context context,
 112                 const char *dirname,
 113                 struct passwd *pwd,
 114                 krb5_principal principal,
 115                 krb5_boolean *result)
 116 {
 117     DIR *d;
 118     struct dirent *dent;
 119     char filename[MAXPATHLEN];
 120     krb5_error_code ret = 0;
 121     struct stat st;
 122
 123     *result = FALSE;
 124
 125     if(lstat(dirname, &st) < 0)
 126         return errno;
 127
 128     if (!S_ISDIR(st.st_mode))
 129         return ENOTDIR;
 130
 131     if (st.st_uid != pwd->pw_uid && st.st_uid != 0)
 132         return EACCES;
 133     if ((st.st_mode & (S_IWGRP | S_IWOTH)) != 0)
 134         return EACCES;
 135
 136     if((d = opendir(dirname)) == NULL)
 137         return errno;
 138
 139     {
 140         int fd;
 141         struct stat st2;
 142
 143         fd = dirfd(d);
 144         if(fstat(fd, &st2) < 0) {
 145             closedir(d);
 146             return errno;
 147         }
 148         if(st.st_dev != st2.st_dev || st.st_ino != st2.st_ino) {
 149             closedir(d);
 150             return EACCES;
 151         }
 152     }
 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 #endif  /* !_WIN32 */
 171
 172 static krb5_boolean
 173 match_local_principals(krb5_context context,
 174                        krb5_principal principal,
 175                        const char *luser)
 176 {
 177     krb5_error_code ret;
 178     krb5_realm *realms, *r;
 179     krb5_boolean result = FALSE;
 180
 181     /* multi-component principals can never match */
 182     if(krb5_principal_get_comp_string(context, principal, 1) != NULL)
 183         return FALSE;
 184
 185     ret = krb5_get_default_realms (context, &realms);
 186     if (ret)
 187         return FALSE;
 188
 189     for (r = realms; *r != NULL; ++r) {
 190         if(strcmp(krb5_principal_get_realm(context, principal),
 191                   *r) != 0)
 192             continue;
 193         if(strcmp(krb5_principal_get_comp_string(context, principal, 0),
 194                   luser) == 0) {
 195             result = TRUE;
 196             break;
 197         }
 198     }
 199     krb5_free_host_realm (context, realms);
 200     return result;
 201 }
 202
 203 /**
 204  * This function takes the name of a local user and checks if
 205  * principal is allowed to log in as that user.
 206  *
 207  * The user may have a ~/.k5login file listing principals that are
 208  * allowed to login as that user. If that file does not exist, all
 209  * principals with a first component identical to the username, and a
 210  * realm considered local, are allowed access.
 211  *
 212  * The .k5login file must contain one principal per line, be owned by
 213  * user and not be writable by group or other (but must be readable by
 214  * anyone).
 215  *
 216  * Note that if the file exists, no implicit access rights are given
 217  * to user@@LOCALREALM.
 218  *
 219  * Optionally, a set of files may be put in ~/.k5login.d (a
 220  * directory), in which case they will all be checked in the same
 221  * manner as .k5login.  The files may be called anything, but files
 222  * starting with a hash (#) , or ending with a tilde (~) are
 223  * ignored. Subdirectories are not traversed. Note that this directory
 224  * may not be checked by other Kerberos implementations.
 225  *
 226  * If no configuration file exists, match user against local domains,
 227  * ie luser@@LOCAL-REALMS-IN-CONFIGURATION-FILES.
 228  *
 229  * @param context Kerberos 5 context.
 230  * @param principal principal to check if allowed to login
 231  * @param luser local user id
 232  *
 233  * @return returns TRUE if access should be granted, FALSE otherwise.
 234  *
 235  * @ingroup krb5_support
 236  */
 237
 238 KRB5_LIB_FUNCTION krb5_boolean KRB5_LIB_CALL
 239 krb5_kuserok (krb5_context context,
 240               krb5_principal principal,
 241               const char *luser)
 242 {
 243 #ifndef _WIN32
 244     char *buf;
 245     size_t buflen;
 246     struct passwd *pwd = NULL;
 247     char *profile_dir = NULL;
 248     krb5_error_code ret;
 249     krb5_boolean result = FALSE;
 250
 251     krb5_boolean found_file = FALSE;
 252
 253 #ifdef POSIX_GETPWNAM_R
 254     char pwbuf[2048];
 255     struct passwd pw;
 256
 257     if(getpwnam_r(luser, &pw, pwbuf, sizeof(pwbuf), &pwd) != 0)
 258         return FALSE;
 259 #else
 260     pwd = getpwnam (luser);
 261 #endif
 262     if (pwd == NULL)
 263         return FALSE;
 264     profile_dir = pwd->pw_dir;
 265
 266 #define KLOGIN "/.k5login"
 267     buflen = strlen(profile_dir) + sizeof(KLOGIN) + 2; /* 2 for .d */
 268     buf = malloc(buflen);
 269     if(buf == NULL)
 270         return FALSE;
 271     /* check user's ~/.k5login */
 272     strlcpy(buf, profile_dir, buflen);
 273     strlcat(buf, KLOGIN, buflen);
 274     ret = check_one_file(context, buf, pwd, principal, &result);
 275
 276     if(ret == 0 && result == TRUE) {
 277         free(buf);
 278         return TRUE;
 279     }
 280
 281     if(ret != ENOENT)
 282         found_file = TRUE;
 283
 284     strlcat(buf, ".d", buflen);
 285     ret = check_directory(context, buf, pwd, principal, &result);
 286     free(buf);
 287     if(ret == 0 && result == TRUE)
 288         return TRUE;
 289
 290     if(ret != ENOENT && ret != ENOTDIR)
 291         found_file = TRUE;
 292
 293     /* finally if no files exist, allow all principals matching
 294        <localuser>@<LOCALREALM> */
 295     if(found_file == FALSE)
 296         return match_local_principals(context, principal, luser);
 297
 298     return FALSE;
 299 #else
 300     /* The .k5login file may be on a remote profile and we don't have
 301        access to the profile until we have a token handle for the
 302        user's credentials. */
 303     return match_local_principals(context, principal, luser);
 304 #endif
 305 }