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 "memcache.h"
  24 #include "../lib/util/util_pw.h"
  25
  26 /* internal functions */
  27 static struct passwd *uname_string_combinations(char *s, TALLOC_CTX *mem_ctx,
  28                                                 struct passwd * (*fn) (TALLOC_CTX *mem_ctx, const char *),
  29                                                 int N);
  30 static struct passwd *uname_string_combinations2(char *s, TALLOC_CTX *mem_ctx, int offset,
  31                                                  struct passwd * (*fn) (TALLOC_CTX *mem_ctx, const char *),
  32                                                  int N);
  33
  34 static struct passwd *getpwnam_alloc_cached(TALLOC_CTX *mem_ctx, const char *name)
  35 {
  36         struct passwd *pw, *for_cache;
  37
  38         pw = (struct passwd *)memcache_lookup_talloc(
  39                 NULL, GETPWNAM_CACHE, data_blob_string_const_null(name));
  40         if (pw != NULL) {
  41                 return tcopy_passwd(mem_ctx, pw);
  42         }
  43
  44         pw = sys_getpwnam(name);
  45         if (pw == NULL) {
  46                 return NULL;
  47         }
  48
  49         for_cache = tcopy_passwd(talloc_tos(), pw);
  50         if (for_cache == NULL) {
  51                 return NULL;
  52         }
  53
  54         memcache_add_talloc(NULL, GETPWNAM_CACHE,
  55                         data_blob_string_const_null(name), &for_cache);
  56
  57         return tcopy_passwd(mem_ctx, pw);
  58 }
  59
  60 /****************************************************************************
  61  Flush all cached passwd structs.
  62 ****************************************************************************/
  63
  64 void flush_pwnam_cache(void)
  65 {
  66         memcache_flush(NULL, GETPWNAM_CACHE);
  67 }
  68
  69 /****************************************************************************
  70  Get a users home directory.
  71 ****************************************************************************/
  72
  73 char *get_user_home_dir(TALLOC_CTX *mem_ctx, const char *user)
  74 {
  75         struct passwd *pass;
  76         char *result;
  77
  78         /* Ensure the user exists. */
  79
  80         pass = Get_Pwnam_alloc(mem_ctx, user);
  81
  82         if (!pass)
  83                 return(NULL);
  84
  85         /* Return home directory from struct passwd. */
  86
  87         result = talloc_move(mem_ctx, &pass->pw_dir);
  88
  89         TALLOC_FREE(pass);
  90         return result;
  91 }
  92
  93 /****************************************************************************
  94  * A wrapper for sys_getpwnam().  The following variations are tried:
  95  *   - as transmitted
  96  *   - in all lower case if this differs from transmitted
  97  *   - in all upper case if this differs from transmitted
  98  *   - using lp_usernamelevel() for permutations.
  99 ****************************************************************************/
 100
 101 static struct passwd *Get_Pwnam_internals(TALLOC_CTX *mem_ctx,
 102                                           const char *user, char *user2)
 103 {
 104         struct passwd *ret = NULL;
 105
 106         if (!user2 || !(*user2))
 107                 return(NULL);
 108
 109         if (!user || !(*user))
 110                 return(NULL);
 111
 112         /* Try in all lower case first as this is the most
 113            common case on UNIX systems */
 114         strlower_m(user2);
 115         DEBUG(5,("Trying _Get_Pwnam(), username as lowercase is %s\n",user2));
 116         ret = getpwnam_alloc_cached(mem_ctx, user2);
 117         if(ret)
 118                 goto done;
 119
 120         /* Try as given, if username wasn't originally lowercase */
 121         if(strcmp(user, user2) != 0) {
 122                 DEBUG(5,("Trying _Get_Pwnam(), username as given is %s\n",
 123                          user));
 124                 ret = getpwnam_alloc_cached(mem_ctx, user);
 125                 if(ret)
 126                         goto done;
 127         }
 128
 129         /* Try as uppercase, if username wasn't originally uppercase */
 130         strupper_m(user2);
 131         if(strcmp(user, user2) != 0) {
 132                 DEBUG(5,("Trying _Get_Pwnam(), username as uppercase is %s\n",
 133                          user2));
 134                 ret = getpwnam_alloc_cached(mem_ctx, user2);
 135                 if(ret)
 136                         goto done;
 137         }
 138
 139         /* Try all combinations up to usernamelevel */
 140         strlower_m(user2);
 141         DEBUG(5,("Checking combinations of %d uppercase letters in %s\n",
 142                  lp_usernamelevel(), user2));
 143         ret = uname_string_combinations(user2, mem_ctx, getpwnam_alloc_cached,
 144                                         lp_usernamelevel());
 145
 146 done:
 147         DEBUG(5,("Get_Pwnam_internals %s find user [%s]!\n",ret ?
 148                  "did":"didn't", user));
 149
 150         return ret;
 151 }
 152
 153 /****************************************************************************
 154  Get_Pwnam wrapper without modification.
 155   NOTE: This with NOT modify 'user'!
 156   This will return an allocated structure
 157 ****************************************************************************/
 158
 159 struct passwd *Get_Pwnam_alloc(TALLOC_CTX *mem_ctx, const char *user)
 160 {
 161         fstring user2;
 162
 163         if ( *user == '\0' ) {
 164                 DEBUG(10,("Get_Pwnam: empty username!\n"));
 165                 return NULL;
 166         }
 167
 168         fstrcpy(user2, user);
 169
 170         DEBUG(5,("Finding user %s\n", user));
 171
 172         return Get_Pwnam_internals(mem_ctx, user, user2);
 173 }
 174
 175 /* The functions below have been taken from password.c and slightly modified */
 176 /****************************************************************************
 177  Apply a function to upper/lower case combinations
 178  of a string and return true if one of them returns true.
 179  Try all combinations with N uppercase letters.
 180  offset is the first char to try and change (start with 0)
 181  it assumes the string starts lowercased
 182 ****************************************************************************/
 183
 184 static struct passwd *uname_string_combinations2(char *s, TALLOC_CTX *mem_ctx,
 185                                                  int offset,
 186                                                  struct passwd *(*fn)(TALLOC_CTX *mem_ctx, const char *),
 187                                                  int N)
 188 {
 189         ssize_t len = (ssize_t)strlen(s);
 190         int i;
 191         struct passwd *ret;
 192
 193         if (N <= 0 || offset >= len)
 194                 return(fn(mem_ctx, s));
 195
 196         for (i=offset;i<(len-(N-1));i++) {
 197                 char c = s[i];
 198                 if (!islower_ascii((int)c))
 199                         continue;
 200                 s[i] = toupper_ascii(c);
 201                 ret = uname_string_combinations2(s, mem_ctx, i+1, fn, N-1);
 202                 if(ret)
 203                         return(ret);
 204                 s[i] = c;
 205         }
 206         return(NULL);
 207 }
 208
 209 /****************************************************************************
 210  Apply a function to upper/lower case combinations
 211  of a string and return true if one of them returns true.
 212  Try all combinations with up to N uppercase letters.
 213  offset is the first char to try and change (start with 0)
 214  it assumes the string starts lowercased
 215 ****************************************************************************/
 216
 217 static struct passwd * uname_string_combinations(char *s, TALLOC_CTX *mem_ctx,
 218                                                  struct passwd * (*fn)(TALLOC_CTX *mem_ctx, const char *),
 219                                                  int N)
 220 {
 221         int n;
 222         struct passwd *ret;
 223
 224         for (n=1;n<=N;n++) {
 225                 ret = uname_string_combinations2(s,mem_ctx,0,fn,n);
 226                 if(ret)
 227                         return(ret);
 228         }
 229         return(NULL);
 230 }
 231