source3/lib/access.c

   1 /*
   2    This module is an adaption of code from the tcpd-1.4 package written
   3    by Wietse Venema, Eindhoven University of Technology, The Netherlands.
   4
   5    The code is used here with permission.
   6
   7    The code has been considerably changed from the original. Bug reports
   8    should be sent to samba-technical@lists.samba.org
   9
  10    Updated for IPv6 by Jeremy Allison (C) 2007.
  11 */
  12
  13 #include "includes.h"
  14 #include "../lib/util/memcache.h"
  15 #include "lib/socket/interfaces.h"
  16
  17 #define NAME_INDEX 0
  18 #define ADDR_INDEX 1
  19
  20 /* masked_match - match address against netnumber/netmask */
  21 static bool masked_match(const char *tok, const char *slash, const char *s)
  22 {
  23         struct sockaddr_storage ss_mask;
  24         struct sockaddr_storage ss_tok;
  25         struct sockaddr_storage ss_host;
  26         char *tok_copy = NULL;
  27
  28         if (!interpret_string_addr(&ss_host, s, 0)) {
  29                 return false;
  30         }
  31
  32         if (*tok == '[') {
  33                 /* IPv6 address - remove braces. */
  34                 tok_copy = SMB_STRDUP(tok+1);
  35                 if (!tok_copy) {
  36                         return false;
  37                 }
  38                 /* Remove the terminating ']' */
  39                 tok_copy[PTR_DIFF(slash,tok)-1] = '\0';
  40         } else {
  41                 tok_copy = SMB_STRDUP(tok);
  42                 if (!tok_copy) {
  43                         return false;
  44                 }
  45                 /* Remove the terminating '/' */
  46                 tok_copy[PTR_DIFF(slash,tok)] = '\0';
  47         }
  48
  49         if (!interpret_string_addr(&ss_tok, tok_copy, 0)) {
  50                 SAFE_FREE(tok_copy);
  51                 return false;
  52         }
  53
  54         SAFE_FREE(tok_copy);
  55
  56         if (strlen(slash + 1) > 2) {
  57                 if (!interpret_string_addr(&ss_mask, slash+1, 0)) {
  58                         return false;
  59                 }
  60         } else {
  61                 char *endp = NULL;
  62                 unsigned long val = strtoul(slash+1, &endp, 0);
  63                 if (slash+1 == endp || (endp && *endp != '\0')) {
  64                         return false;
  65                 }
  66                 if (!make_netmask(&ss_mask, &ss_tok, val)) {
  67                         return false;
  68                 }
  69         }
  70
  71         return same_net((struct sockaddr *)(void *)&ss_host,
  72                         (struct sockaddr *)(void *)&ss_tok,
  73                         (struct sockaddr *)(void *)&ss_mask);
  74 }
  75
  76 /* string_match - match string s against token tok */
  77 static bool string_match(const char *tok,const char *s)
  78 {
  79         size_t     tok_len;
  80         size_t     str_len;
  81         const char   *cut;
  82
  83         /* Return true if a token has the magic value "ALL". Return
  84          * true if the token is "FAIL". If the token starts with a "."
  85          * (domain name), return true if it matches the last fields of
  86          * the string. If the token has the magic value "LOCAL",
  87          * return true if the string does not contain a "."
  88          * character. If the token ends on a "." (network number),
  89          * return true if it matches the first fields of the
  90          * string. If the token begins with a "@" (netgroup name),
  91          * return true if the string is a (host) member of the
  92          * netgroup. Return true if the token fully matches the
  93          * string. If the token is a netnumber/netmask pair, return
  94          * true if the address is a member of the specified subnet.
  95          */
  96
  97         if (tok[0] == '.') {                    /* domain: match last fields */
  98                 if ((str_len = strlen(s)) > (tok_len = strlen(tok))
  99                     && strequal(tok, s + str_len - tok_len)) {
 100                         return true;
 101                 }
 102         } else if (tok[0] == '@') { /* netgroup: look it up */
 103 #ifdef  HAVE_NETGROUP
 104                 DATA_BLOB tmp;
 105                 char *mydomain = NULL;
 106                 char *hostname = NULL;
 107                 bool netgroup_ok = false;
 108
 109                 if (memcache_lookup(
 110                             NULL, SINGLETON_CACHE,
 111                             data_blob_string_const_null("yp_default_domain"),
 112                             &tmp)) {
 113
 114                         SMB_ASSERT(tmp.length > 0);
 115                         mydomain = (tmp.data[0] == '\0')
 116                                 ? NULL : (char *)tmp.data;
 117                 }
 118                 else {
 119                         yp_get_default_domain(&mydomain);
 120
 121                         memcache_add(
 122                                 NULL, SINGLETON_CACHE,
 123                                 data_blob_string_const_null("yp_default_domain"),
 124                                 data_blob_string_const_null(mydomain?mydomain:""));
 125                 }
 126
 127                 if (!mydomain) {
 128                         DEBUG(0,("Unable to get default yp domain. "
 129                                 "Try without it.\n"));
 130                 }
 131                 if (!(hostname = SMB_STRDUP(s))) {
 132                         DEBUG(1,("out of memory for strdup!\n"));
 133                         return false;
 134                 }
 135
 136                 netgroup_ok = innetgr(tok + 1, hostname, (char *) 0, mydomain);
 137
 138                 DEBUG(5,("looking for %s of domain %s in netgroup %s gave %s\n",
 139                          hostname,
 140                          mydomain?mydomain:"(ANY)",
 141                          tok+1,
 142                          BOOLSTR(netgroup_ok)));
 143
 144                 SAFE_FREE(hostname);
 145
 146                 if (netgroup_ok)
 147                         return true;
 148 #else
 149                 DEBUG(0,("access: netgroup support is not configured\n"));
 150                 return false;
 151 #endif
 152         } else if (strequal(tok, "ALL")) {      /* all: match any */
 153                 return true;
 154         } else if (strequal(tok, "FAIL")) {     /* fail: match any */
 155                 return true;
 156         } else if (strequal(tok, "LOCAL")) {    /* local: no dots */
 157                 if (strchr_m(s, '.') == 0 && !strequal(s, "unknown")) {
 158                         return true;
 159                 }
 160         } else if (strequal(tok, s)) {   /* match host name or address */
 161                 return true;
 162         } else if (tok[(tok_len = strlen(tok)) - 1] == '.') {   /* network */
 163                 if (strncmp(tok, s, tok_len) == 0) {
 164                         return true;
 165                 }
 166         } else if ((cut = strchr_m(tok, '/')) != 0) {   /* netnumber/netmask */
 167                 if ((isdigit(s[0]) && strchr_m(tok, '.') != NULL) ||
 168                         (tok[0] == '[' && cut > tok && cut[-1] == ']') ||
 169                         ((isxdigit(s[0]) || s[0] == ':') &&
 170                                 strchr_m(tok, ':') != NULL)) {
 171                         /* IPv4/netmask or
 172                          * [IPv6:addr]/netmask or IPv6:addr/netmask */
 173                         return masked_match(tok, cut, s);
 174                 }
 175         } else if (strchr_m(tok, '*') != 0 || strchr_m(tok, '?')) {
 176                 return unix_wild_match(tok, s);
 177         }
 178         return false;
 179 }
 180
 181 /* client_match - match host name and address against token */
 182 bool client_match(const char *tok, const void *item)
 183 {
 184         const char **client = discard_const_p(const char *, item);
 185         const char *tok_addr = tok;
 186         const char *cli_addr = client[ADDR_INDEX];
 187
 188         /*
 189          * tok and client[ADDR_INDEX] can be an IPv4 mapped to IPv6,
 190          * we try and match the IPv4 part of address only.
 191          * Bug #5311 and #7383.
 192          */
 193
 194         if (strnequal(tok_addr, "::ffff:",7)) {
 195                 tok_addr += 7;
 196         }
 197
 198         if (strnequal(cli_addr,"::ffff:",7)) {
 199                 cli_addr += 7;
 200         }
 201
 202         /*
 203          * Try to match the address first. If that fails, try to match the host
 204          * name if available.
 205          */
 206
 207         if (string_match(tok_addr, cli_addr)) {
 208                 return true;
 209         }
 210
 211         if (client[NAME_INDEX][0] != 0) {
 212                 if (string_match(tok, client[NAME_INDEX])) {
 213                         return true;
 214                 }
 215         }
 216
 217         return false;
 218 }
 219
 220 /* list_match - match an item against a list of tokens with exceptions */
 221 bool list_match(const char **list,const void *item,
 222                 bool (*match_fn)(const char *, const void *))
 223 {
 224         bool match = false;
 225
 226         if (!list) {
 227                 return false;
 228         }
 229
 230         /*
 231          * Process tokens one at a time. We have exhausted all possible matches
 232          * when we reach an "EXCEPT" token or the end of the list. If we do find
 233          * a match, look for an "EXCEPT" list and recurse to determine whether
 234          * the match is affected by any exceptions.
 235          */
 236
 237         for (; *list ; list++) {
 238                 if (strequal(*list, "EXCEPT")) {
 239                         /* EXCEPT: give up */
 240                         break;
 241                 }
 242                 if ((match = (*match_fn) (*list, item))) {
 243                         /* true or FAIL */
 244                         break;
 245                 }
 246         }
 247         /* Process exceptions to true or FAIL matches. */
 248
 249         if (match != false) {
 250                 while (*list  && !strequal(*list, "EXCEPT")) {
 251                         list++;
 252                 }
 253
 254                 for (; *list; list++) {
 255                         if ((*match_fn) (*list, item)) {
 256                                 /* Exception Found */
 257                                 return false;
 258                         }
 259                 }
 260         }
 261
 262         return match;
 263 }
 264
 265 /* return true if access should be allowed */
 266 static bool allow_access_internal(const char **deny_list,
 267                                 const char **allow_list,
 268                                 const char *cname,
 269                                 const char *caddr)
 270 {
 271         const char *client[2];
 272
 273         client[NAME_INDEX] = cname;
 274         client[ADDR_INDEX] = caddr;
 275
 276         /* if it is loopback then always allow unless specifically denied */
 277         if (strcmp(caddr, "127.0.0.1") == 0 || strcmp(caddr, "::1") == 0) {
 278                 /*
 279                  * If 127.0.0.1 matches both allow and deny then allow.
 280                  * Patch from Steve Langasek vorlon@netexpress.net.
 281                  */
 282                 if (deny_list &&
 283                         list_match(deny_list,client,client_match) &&
 284                                 (!allow_list ||
 285                                 !list_match(allow_list,client, client_match))) {
 286                         return false;
 287                 }
 288                 return true;
 289         }
 290
 291         /* if theres no deny list and no allow list then allow access */
 292         if ((!deny_list || *deny_list == 0) &&
 293             (!allow_list || *allow_list == 0)) {
 294                 return true;
 295         }
 296
 297         /* if there is an allow list but no deny list then allow only hosts
 298            on the allow list */
 299         if (!deny_list || *deny_list == 0) {
 300                 return(list_match(allow_list,client,client_match));
 301         }
 302
 303         /* if theres a deny list but no allow list then allow
 304            all hosts not on the deny list */
 305         if (!allow_list || *allow_list == 0) {
 306                 return(!list_match(deny_list,client,client_match));
 307         }
 308
 309         /* if there are both types of list then allow all hosts on the
 310            allow list */
 311         if (list_match(allow_list,(const char *)client,client_match)) {
 312                 return true;
 313         }
 314
 315         /* if there are both types of list and it's not on the allow then
 316            allow it if its not on the deny */
 317         if (list_match(deny_list,(const char *)client,client_match)) {
 318                 return false;
 319         }
 320
 321         return true;
 322 }
 323
 324 /* return true if access should be allowed */
 325 bool allow_access(const char **deny_list,
 326                 const char **allow_list,
 327                 const char *cname,
 328                 const char *caddr)
 329 {
 330         bool ret;
 331         char *nc_cname = smb_xstrdup(cname);
 332         char *nc_caddr = smb_xstrdup(caddr);
 333
 334         ret = allow_access_internal(deny_list, allow_list, nc_cname, nc_caddr);
 335
 336         DEBUG(ret ? 3 : 0,
 337               ("%s connection from %s (%s)\n",
 338                ret ? "Allowed" : "Denied", nc_cname, nc_caddr));
 339
 340         SAFE_FREE(nc_cname);
 341         SAFE_FREE(nc_caddr);
 342         return ret;
 343 }