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