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 #include "lib/util/string_wrappers.h"
  27
  28 /* internal functions */
  29 static struct passwd *uname_string_combinations(char *s, TALLOC_CTX *mem_ctx,
  30                                                 struct passwd * (*fn) (TALLOC_CTX *mem_ctx, const char *),
  31                                                 int N);
  32 static struct passwd *uname_string_combinations2(char *s, TALLOC_CTX *mem_ctx, int offset,
  33                                                  struct passwd * (*fn) (TALLOC_CTX *mem_ctx, const char *),
  34                                                  int N);
  35
  36 static struct passwd *getpwnam_alloc_cached(TALLOC_CTX *mem_ctx, const char *name)
  37 {
  38         struct passwd *pw, *for_cache;
  39
  40         pw = (struct passwd *)memcache_lookup_talloc(
  41                 NULL, GETPWNAM_CACHE, data_blob_string_const_null(name));
  42         if (pw != NULL) {
  43                 return tcopy_passwd(mem_ctx, pw);
  44         }
  45
  46         pw = getpwnam(name);
  47         if (pw == NULL) {
  48                 return NULL;
  49         }
  50
  51         for_cache = tcopy_passwd(talloc_tos(), pw);
  52         if (for_cache == NULL) {
  53                 return NULL;
  54         }
  55
  56         memcache_add_talloc(NULL, GETPWNAM_CACHE,
  57                         data_blob_string_const_null(name), &for_cache);
  58
  59         return tcopy_passwd(mem_ctx, pw);
  60 }
  61
  62 /****************************************************************************
  63  Flush all cached passwd structs.
  64 ****************************************************************************/
  65
  66 void flush_pwnam_cache(void)
  67 {
  68         memcache_flush(NULL, GETPWNAM_CACHE);
  69 }
  70
  71 /****************************************************************************
  72  Get a users home directory.
  73 ****************************************************************************/
  74
  75 char *get_user_home_dir(TALLOC_CTX *mem_ctx, const char *user)
  76 {
  77         struct passwd *pass;
  78         char *result;
  79
  80         /* Ensure the user exists. */
  81
  82         pass = Get_Pwnam_alloc(mem_ctx, user);
  83
  84         if (!pass)
  85                 return(NULL);
  86
  87         /* Return home directory from struct passwd. */
  88
  89         result = talloc_move(mem_ctx, &pass->pw_dir);
  90
  91         TALLOC_FREE(pass);
  92         return result;
  93 }
  94
  95 /****************************************************************************
  96  * A wrapper for getpwnam().  The following variations are tried:
  97  *   - as transmitted
  98  *   - in all lower case if this differs from transmitted
  99  *   - in all upper case if this differs from transmitted
 100  *   - using lp_username_level() for permutations.
 101 ****************************************************************************/
 102
 103 static struct passwd *Get_Pwnam_internals(TALLOC_CTX *mem_ctx,
 104                                           const char *user, char *user2)
 105 {
 106         struct passwd *ret = NULL;
 107
 108         if (!user2 || !(*user2))
 109                 return(NULL);
 110
 111         if (!user || !(*user))
 112                 return(NULL);
 113
 114         /* Try in all lower case first as this is the most
 115            common case on UNIX systems */
 116         if (!strlower_m(user2)) {
 117                 DEBUG(5,("strlower_m %s failed\n", user2));
 118                 goto done;
 119         }
 120
 121         DEBUG(5,("Trying _Get_Pwnam(), username as lowercase is %s\n",user2));
 122         ret = getpwnam_alloc_cached(mem_ctx, user2);
 123         if(ret)
 124                 goto done;
 125
 126         /* Try as given, if username wasn't originally lowercase */
 127         if(strcmp(user, user2) != 0) {
 128                 DEBUG(5,("Trying _Get_Pwnam(), username as given is %s\n",
 129                          user));
 130                 ret = getpwnam_alloc_cached(mem_ctx, user);
 131                 if(ret)
 132                         goto done;
 133         }
 134
 135         /* Try as uppercase, if username wasn't originally uppercase */
 136         if (!strupper_m(user2)) {
 137                 goto done;
 138         }
 139
 140         if(strcmp(user, user2) != 0) {
 141                 DEBUG(5,("Trying _Get_Pwnam(), username as uppercase is %s\n",
 142                          user2));
 143                 ret = getpwnam_alloc_cached(mem_ctx, user2);
 144                 if(ret)
 145                         goto done;
 146         }
 147
 148         /* Try all combinations up to usernamelevel */
 149         if (!strlower_m(user2)) {
 150                 DEBUG(5,("strlower_m %s failed\n", user2));
 151                 goto done;
 152         }
 153         DEBUG(5,("Checking combinations of %d uppercase letters in %s\n",
 154                  lp_username_level(), user2));
 155         ret = uname_string_combinations(user2, mem_ctx, getpwnam_alloc_cached,
 156                                         lp_username_level());
 157
 158 done:
 159         DEBUG(5,("Get_Pwnam_internals %s find user [%s]!\n",ret ?
 160                  "did":"didn't", user));
 161
 162         return ret;
 163 }
 164
 165 /****************************************************************************
 166  Get_Pwnam wrapper without modification.
 167   NOTE: This with NOT modify 'user'!
 168   This will return an allocated structure
 169 ****************************************************************************/
 170
 171 struct passwd *Get_Pwnam_alloc(TALLOC_CTX *mem_ctx, const char *user)
 172 {
 173         fstring user2;
 174
 175         if ( *user == '\0' ) {
 176                 DEBUG(10,("Get_Pwnam: empty username!\n"));
 177                 return NULL;
 178         }
 179
 180         fstrcpy(user2, user);
 181
 182         DEBUG(5,("Finding user %s\n", user));
 183
 184         return Get_Pwnam_internals(mem_ctx, user, user2);
 185 }
 186
 187 /* The functions below have been taken from password.c and slightly modified */
 188 /****************************************************************************
 189  Apply a function to upper/lower case combinations
 190  of a string and return true if one of them returns true.
 191  Try all combinations with N uppercase letters.
 192  offset is the first char to try and change (start with 0)
 193  it assumes the string starts lowercased
 194 ****************************************************************************/
 195
 196 static struct passwd *uname_string_combinations2(char *s, TALLOC_CTX *mem_ctx,
 197                                                  int offset,
 198                                                  struct passwd *(*fn)(TALLOC_CTX *mem_ctx, const char *),
 199                                                  int N)
 200 {
 201         ssize_t len = (ssize_t)strlen(s);
 202         int i;
 203         struct passwd *ret;
 204
 205         if (N <= 0 || offset >= len)
 206                 return(fn(mem_ctx, s));
 207
 208         for (i=offset;i<(len-(N-1));i++) {
 209                 char c = s[i];
 210                 if (!islower_m((int)c))
 211                         continue;
 212                 s[i] = toupper_m(c);
 213                 ret = uname_string_combinations2(s, mem_ctx, i+1, fn, N-1);
 214                 if(ret)
 215                         return(ret);
 216                 s[i] = c;
 217         }
 218         return(NULL);
 219 }
 220
 221 /****************************************************************************
 222  Apply a function to upper/lower case combinations
 223  of a string and return true if one of them returns true.
 224  Try all combinations with up to N uppercase letters.
 225  offset is the first char to try and change (start with 0)
 226  it assumes the string starts lowercased
 227 ****************************************************************************/
 228
 229 static struct passwd * uname_string_combinations(char *s, TALLOC_CTX *mem_ctx,
 230                                                  struct passwd * (*fn)(TALLOC_CTX *mem_ctx, const char *),
 231                                                  int N)
 232 {
 233         int n;
 234         struct passwd *ret;
 235
 236         for (n=1;n<=N;n++) {
 237                 ret = uname_string_combinations2(s,mem_ctx,0,fn,n);
 238                 if(ret)
 239                         return(ret);
 240         }
 241         return(NULL);
 242 }
 243