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 "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         strlower_m(user2);
 116         DEBUG(5,("Trying _Get_Pwnam(), username as lowercase is %s\n",user2));
 117         ret = getpwnam_alloc_cached(mem_ctx, user2);
 118         if(ret)
 119                 goto done;
 120
 121         /* Try as given, if username wasn't originally lowercase */
 122         if(strcmp(user, user2) != 0) {
 123                 DEBUG(5,("Trying _Get_Pwnam(), username as given is %s\n",
 124                          user));
 125                 ret = getpwnam_alloc_cached(mem_ctx, user);
 126                 if(ret)
 127                         goto done;
 128         }
 129
 130         /* Try as uppercase, if username wasn't originally uppercase */
 131         strupper_m(user2);
 132         if(strcmp(user, user2) != 0) {
 133                 DEBUG(5,("Trying _Get_Pwnam(), username as uppercase is %s\n",
 134                          user2));
 135                 ret = getpwnam_alloc_cached(mem_ctx, user2);
 136                 if(ret)
 137                         goto done;
 138         }
 139
 140         /* Try all combinations up to usernamelevel */
 141         strlower_m(user2);
 142         DEBUG(5,("Checking combinations of %d uppercase letters in %s\n",
 143                  lp_usernamelevel(), user2));
 144         ret = uname_string_combinations(user2, mem_ctx, getpwnam_alloc_cached,
 145                                         lp_usernamelevel());
 146
 147 done:
 148         DEBUG(5,("Get_Pwnam_internals %s find user [%s]!\n",ret ?
 149                  "did":"didn't", user));
 150
 151         return ret;
 152 }
 153
 154 /****************************************************************************
 155  Get_Pwnam wrapper without modification.
 156   NOTE: This with NOT modify 'user'!
 157   This will return an allocated structure
 158 ****************************************************************************/
 159
 160 struct passwd *Get_Pwnam_alloc(TALLOC_CTX *mem_ctx, const char *user)
 161 {
 162         fstring user2;
 163
 164         if ( *user == '\0' ) {
 165                 DEBUG(10,("Get_Pwnam: empty username!\n"));
 166                 return NULL;
 167         }
 168
 169         fstrcpy(user2, user);
 170
 171         DEBUG(5,("Finding user %s\n", user));
 172
 173         return Get_Pwnam_internals(mem_ctx, user, user2);
 174 }
 175
 176 /* The functions below have been taken from password.c and slightly modified */
 177 /****************************************************************************
 178  Apply a function to upper/lower case combinations
 179  of a string and return true if one of them returns true.
 180  Try all combinations with N uppercase letters.
 181  offset is the first char to try and change (start with 0)
 182  it assumes the string starts lowercased
 183 ****************************************************************************/
 184
 185 static struct passwd *uname_string_combinations2(char *s, TALLOC_CTX *mem_ctx,
 186                                                  int offset,
 187                                                  struct passwd *(*fn)(TALLOC_CTX *mem_ctx, const char *),
 188                                                  int N)
 189 {
 190         ssize_t len = (ssize_t)strlen(s);
 191         int i;
 192         struct passwd *ret;
 193
 194         if (N <= 0 || offset >= len)
 195                 return(fn(mem_ctx, s));
 196
 197         for (i=offset;i<(len-(N-1));i++) {
 198                 char c = s[i];
 199                 if (!islower_m((int)c))
 200                         continue;
 201                 s[i] = toupper_m(c);
 202                 ret = uname_string_combinations2(s, mem_ctx, i+1, fn, N-1);
 203                 if(ret)
 204                         return(ret);
 205                 s[i] = c;
 206         }
 207         return(NULL);
 208 }
 209
 210 /****************************************************************************
 211  Apply a function to upper/lower case combinations
 212  of a string and return true if one of them returns true.
 213  Try all combinations with up to N uppercase letters.
 214  offset is the first char to try and change (start with 0)
 215  it assumes the string starts lowercased
 216 ****************************************************************************/
 217
 218 static struct passwd * uname_string_combinations(char *s, TALLOC_CTX *mem_ctx,
 219                                                  struct passwd * (*fn)(TALLOC_CTX *mem_ctx, const char *),
 220                                                  int N)
 221 {
 222         int n;
 223         struct passwd *ret;
 224
 225         for (n=1;n<=N;n++) {
 226                 ret = uname_string_combinations2(s,mem_ctx,0,fn,n);
 227                 if(ret)
 228                         return(ret);
 229         }
 230         return(NULL);
 231 }
 232