source3/lib/username.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Username handling
   4    Copyright (C) Andrew Tridgell 1992-1998
   5    Copyright (C) Jeremy Allison 1997-2001.
   6    Copyright (C) Andrew Bartlett 2002
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "includes.h"
  23 #include "system/passwd.h"
  24 #include "../lib/util/memcache.h"
  25 #include "../lib/util/util_pw.h"
  26
  27 /* internal functions */
  28 static struct passwd *uname_string_combinations(char *s, TALLOC_CTX *mem_ctx,
  29                                                 struct passwd * (*fn) (TALLOC_CTX *mem_ctx, const char *),
  30                                                 int N);
  31 static struct passwd *uname_string_combinations2(char *s, TALLOC_CTX *mem_ctx, int offset,
  32                                                  struct passwd * (*fn) (TALLOC_CTX *mem_ctx, const char *),
  33                                                  int N);
  34
  35 static struct passwd *getpwnam_alloc_cached(TALLOC_CTX *mem_ctx, const char *name)
  36 {
  37         struct passwd *pw, *for_cache;
  38
  39         pw = (struct passwd *)memcache_lookup_talloc(
  40                 NULL, GETPWNAM_CACHE, data_blob_string_const_null(name));
  41         if (pw != NULL) {
  42                 return tcopy_passwd(mem_ctx, pw);
  43         }
  44
  45         pw = getpwnam(name);
  46         if (pw == NULL) {
  47                 return NULL;
  48         }
  49
  50         for_cache = tcopy_passwd(talloc_tos(), pw);
  51         if (for_cache == NULL) {
  52                 return NULL;
  53         }
  54
  55         memcache_add_talloc(NULL, GETPWNAM_CACHE,
  56                         data_blob_string_const_null(name), &for_cache);
  57
  58         return tcopy_passwd(mem_ctx, pw);
  59 }
  60
  61 /****************************************************************************
  62  Flush all cached passwd structs.
  63 ****************************************************************************/
  64
  65 void flush_pwnam_cache(void)
  66 {
  67         memcache_flush(NULL, GETPWNAM_CACHE);
  68 }
  69
  70 /****************************************************************************
  71  Get a users home directory.
  72 ****************************************************************************/
  73
  74 char *get_user_home_dir(TALLOC_CTX *mem_ctx, const char *user)
  75 {
  76         struct passwd *pass;
  77         char *result;
  78
  79         /* Ensure the user exists. */
  80
  81         pass = Get_Pwnam_alloc(mem_ctx, user);
  82
  83         if (!pass)
  84                 return(NULL);
  85
  86         /* Return home directory from struct passwd. */
  87
  88         result = talloc_move(mem_ctx, &pass->pw_dir);
  89
  90         TALLOC_FREE(pass);
  91         return result;
  92 }
  93
  94 /****************************************************************************
  95  * A wrapper for getpwnam().  The following variations are tried:
  96  *   - as transmitted
  97  *   - in all lower case if this differs from transmitted
  98  *   - in all upper case if this differs from transmitted
  99  *   - using lp_usernamelevel() for permutations.
 100 ****************************************************************************/
 101
 102 static struct passwd *Get_Pwnam_internals(TALLOC_CTX *mem_ctx,
 103                                           const char *user, char *user2)
 104 {
 105         struct passwd *ret = NULL;
 106
 107         if (!user2 || !(*user2))
 108                 return(NULL);
 109
 110         if (!user || !(*user))
 111                 return(NULL);
 112
 113         /* Try in all lower case first as this is the most
 114            common case on UNIX systems */
 115         if (!strlower_m(user2)) {
 116                 DEBUG(5,("strlower_m %s failed\n", user2));
 117                 goto done;
 118         }
 119
 120         DEBUG(5,("Trying _Get_Pwnam(), username as lowercase is %s\n",user2));
 121         ret = getpwnam_alloc_cached(mem_ctx, user2);
 122         if(ret)
 123                 goto done;
 124
 125         /* Try as given, if username wasn't originally lowercase */
 126         if(strcmp(user, user2) != 0) {
 127                 DEBUG(5,("Trying _Get_Pwnam(), username as given is %s\n",
 128                          user));
 129                 ret = getpwnam_alloc_cached(mem_ctx, user);
 130                 if(ret)
 131                         goto done;
 132         }
 133
 134         /* Try as uppercase, if username wasn't originally uppercase */
 135         if (!strupper_m(user2)) {
 136                 goto done;
 137         }
 138
 139         if(strcmp(user, user2) != 0) {
 140                 DEBUG(5,("Trying _Get_Pwnam(), username as uppercase is %s\n",
 141                          user2));
 142                 ret = getpwnam_alloc_cached(mem_ctx, user2);
 143                 if(ret)
 144                         goto done;
 145         }
 146
 147         /* Try all combinations up to usernamelevel */
 148         if (!strlower_m(user2)) {
 149                 DEBUG(5,("strlower_m %s failed\n", user2));
 150                 goto done;
 151         }
 152         DEBUG(5,("Checking combinations of %d uppercase letters in %s\n",
 153                  lp_usernamelevel(), user2));
 154         ret = uname_string_combinations(user2, mem_ctx, getpwnam_alloc_cached,
 155                                         lp_usernamelevel());
 156
 157 done:
 158         DEBUG(5,("Get_Pwnam_internals %s find user [%s]!\n",ret ?
 159                  "did":"didn't", user));
 160
 161         return ret;
 162 }
 163
 164 /****************************************************************************
 165  Get_Pwnam wrapper without modification.
 166   NOTE: This with NOT modify 'user'!
 167   This will return an allocated structure
 168 ****************************************************************************/
 169
 170 struct passwd *Get_Pwnam_alloc(TALLOC_CTX *mem_ctx, const char *user)
 171 {
 172         fstring user2;
 173
 174         if ( *user == '\0' ) {
 175                 DEBUG(10,("Get_Pwnam: empty username!\n"));
 176                 return NULL;
 177         }
 178
 179         fstrcpy(user2, user);
 180
 181         DEBUG(5,("Finding user %s\n", user));
 182
 183         return Get_Pwnam_internals(mem_ctx, user, user2);
 184 }
 185
 186 /* The functions below have been taken from password.c and slightly modified */
 187 /****************************************************************************
 188  Apply a function to upper/lower case combinations
 189  of a string and return true if one of them returns true.
 190  Try all combinations with N uppercase letters.
 191  offset is the first char to try and change (start with 0)
 192  it assumes the string starts lowercased
 193 ****************************************************************************/
 194
 195 static struct passwd *uname_string_combinations2(char *s, TALLOC_CTX *mem_ctx,
 196                                                  int offset,
 197                                                  struct passwd *(*fn)(TALLOC_CTX *mem_ctx, const char *),
 198                                                  int N)
 199 {
 200         ssize_t len = (ssize_t)strlen(s);
 201         int i;
 202         struct passwd *ret;
 203
 204         if (N <= 0 || offset >= len)
 205                 return(fn(mem_ctx, s));
 206
 207         for (i=offset;i<(len-(N-1));i++) {
 208                 char c = s[i];
 209                 if (!islower_m((int)c))
 210                         continue;
 211                 s[i] = toupper_m(c);
 212                 ret = uname_string_combinations2(s, mem_ctx, i+1, fn, N-1);
 213                 if(ret)
 214                         return(ret);
 215                 s[i] = c;
 216         }
 217         return(NULL);
 218 }
 219
 220 /****************************************************************************
 221  Apply a function to upper/lower case combinations
 222  of a string and return true if one of them returns true.
 223  Try all combinations with up to N uppercase letters.
 224  offset is the first char to try and change (start with 0)
 225  it assumes the string starts lowercased
 226 ****************************************************************************/
 227
 228 static struct passwd * uname_string_combinations(char *s, TALLOC_CTX *mem_ctx,
 229                                                  struct passwd * (*fn)(TALLOC_CTX *mem_ctx, const char *),
 230                                                  int N)
 231 {
 232         int n;
 233         struct passwd *ret;
 234
 235         for (n=1;n<=N;n++) {
 236                 ret = uname_string_combinations2(s,mem_ctx,0,fn,n);
 237                 if(ret)
 238                         return(ret);
 239         }
 240         return(NULL);
 241 }
 242