source/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
  11 #include "includes.h"
  12
  13 #define FAIL            (-1)
  14
  15 #define ALLONES  ((uint32)0xFFFFFFFF)
  16
  17 /* masked_match - match address against netnumber/netmask */
  18 static int masked_match(char *tok, char *slash, char *s)
  19 {
  20         uint32 net;
  21         uint32 mask;
  22         uint32 addr;
  23
  24         if ((addr = interpret_addr(s)) == INADDR_NONE)
  25                 return (False);
  26         *slash = 0;
  27         net = interpret_addr(tok);
  28         *slash = '/';
  29
  30         if (strlen(slash + 1) > 2) {
  31                 mask = interpret_addr(slash + 1);
  32         } else {
  33                 mask = (uint32)((ALLONES << atoi(slash + 1)) ^ ALLONES);
  34         }
  35
  36         if (net == INADDR_NONE || mask == INADDR_NONE) {
  37                 DEBUG(0,("access: bad net/mask access control: %s\n", tok));
  38                 return (False);
  39         }
  40         return ((addr & mask) == net);
  41 }
  42
  43 /* string_match - match string against token */
  44 static int string_match(char *tok,char *s, char *invalid_char)
  45 {
  46         size_t     tok_len;
  47         size_t     str_len;
  48         char   *cut;
  49
  50         *invalid_char = '\0';
  51
  52         /* Return True if a token has the magic value "ALL". Return
  53          * FAIL if the token is "FAIL". If the token starts with a "."
  54          * (domain name), return True if it matches the last fields of
  55          * the string. If the token has the magic value "LOCAL",
  56          * return True if the string does not contain a "."
  57          * character. If the token ends on a "." (network number),
  58          * return True if it matches the first fields of the
  59          * string. If the token begins with a "@" (netgroup name),
  60          * return True if the string is a (host) member of the
  61          * netgroup. Return True if the token fully matches the
  62          * string. If the token is a netnumber/netmask pair, return
  63          * True if the address is a member of the specified subnet.
  64          */
  65
  66         if (tok[0] == '.') {                    /* domain: match last fields */
  67                 if ((str_len = strlen(s)) > (tok_len = strlen(tok))
  68                     && strcasecmp(tok, s + str_len - tok_len) == 0)
  69                         return (True);
  70         } else if (tok[0] == '@') { /* netgroup: look it up */
  71 #ifdef  HAVE_NETGROUP
  72                 static char *mydomain = NULL;
  73                 char *hostname = NULL;
  74                 BOOL netgroup_ok = False;
  75
  76                 if (!mydomain) yp_get_default_domain(&mydomain);
  77
  78                 if (!mydomain) {
  79                         DEBUG(0,("Unable to get default yp domain.\n"));
  80                         return False;
  81                 }
  82                 if (!(hostname = strdup(s))) {
  83                         DEBUG(1,("out of memory for strdup!\n"));
  84                         return False;
  85                 }
  86
  87                 netgroup_ok = innetgr(tok + 1, hostname, (char *) 0, mydomain);
  88
  89                 DEBUG(5,("looking for %s of domain %s in netgroup %s gave %s\n",
  90                          hostname,
  91                          mydomain,
  92                          tok+1,
  93                          BOOLSTR(netgroup_ok)));
  94
  95                 SAFE_FREE(hostname);
  96
  97                 if (netgroup_ok) return(True);
  98 #else
  99                 DEBUG(0,("access: netgroup support is not configured\n"));
 100                 return (False);
 101 #endif
 102         } else if (strcasecmp(tok, "ALL") == 0) {       /* all: match any */
 103                 return (True);
 104         } else if (strcasecmp(tok, "FAIL") == 0) {      /* fail: match any */
 105                 return (FAIL);
 106         } else if (strcasecmp(tok, "LOCAL") == 0) {     /* local: no dots */
 107                 if (strchr_m(s, '.') == 0 && strcasecmp(s, "unknown") != 0)
 108                         return (True);
 109         } else if (!strcasecmp(tok, s)) {   /* match host name or address */
 110                 return (True);
 111         } else if (tok[(tok_len = strlen(tok)) - 1] == '.') {   /* network */
 112                 if (strncmp(tok, s, tok_len) == 0)
 113                         return (True);
 114         } else if ((cut = strchr_m(tok, '/')) != 0) {   /* netnumber/netmask */
 115                 if (isdigit((int)s[0]) && masked_match(tok, cut, s))
 116                         return (True);
 117         } else if (strchr_m(tok, '*') != 0) {
 118                 *invalid_char = '*';
 119         } else if (strchr_m(tok, '?') != 0) {
 120                 *invalid_char = '?';
 121         }
 122         return (False);
 123 }
 124
 125
 126 /* client_match - match host name and address against token */
 127 static int client_match(char *tok,char *item)
 128 {
 129     char **client = (char **)item;
 130     int     match;
 131         char invalid_char = '\0';
 132
 133     /*
 134      * Try to match the address first. If that fails, try to match the host
 135      * name if available.
 136      */
 137
 138     if ((match = string_match(tok, client[1], &invalid_char)) == 0) {
 139                 if(invalid_char)
 140                         DEBUG(0,("client_match: address match failing due to invalid character '%c' found in \
 141 token '%s' in an allow/deny hosts line.\n", invalid_char, tok ));
 142
 143                 if (client[0][0] != 0)
 144                         match = string_match(tok, client[0], &invalid_char);
 145
 146                 if(invalid_char)
 147                         DEBUG(0,("client_match: address match failing due to invalid character '%c' found in \
 148 token '%s' in an allow/deny hosts line.\n", invalid_char, tok ));
 149         }
 150
 151     return (match);
 152 }
 153
 154 /* list_match - match an item against a list of tokens with exceptions */
 155 static int list_match(char **list,char *item, int (*match_fn)(char *, char *))
 156 {
 157     int     match = False;
 158
 159     if (!list) return False;
 160
 161     /*
 162      * Process tokens one at a time. We have exhausted all possible matches
 163      * when we reach an "EXCEPT" token or the end of the list. If we do find
 164      * a match, look for an "EXCEPT" list and recurse to determine whether
 165      * the match is affected by any exceptions.
 166      */
 167
 168     for (; *list ; list++) {
 169         if (strcasecmp(*list, "EXCEPT") == 0)   /* EXCEPT: give up */
 170             break;
 171         if ((match = (*match_fn) (*list, item)))        /* True or FAIL */
 172             break;
 173     }
 174     /* Process exceptions to True or FAIL matches. */
 175
 176     if (match != False) {
 177         while (*list  && strcasecmp(*list, "EXCEPT"))
 178                 list++;
 179
 180         for (; *list; list++) {
 181                 if ((*match_fn) (*list, item)) /* Exception Found */
 182                         return False;
 183         }
 184     }
 185
 186     return (match);
 187 }
 188
 189
 190 /* return true if access should be allowed */
 191 static BOOL allow_access_internal(char **deny_list,char **allow_list,
 192                   char *cname,char *caddr)
 193 {
 194         char *client[2];
 195
 196         client[0] = cname;
 197         client[1] = caddr;
 198
 199         /* if it is loopback then always allow unless specifically denied */
 200         if (strcmp(caddr, "127.0.0.1") == 0) {
 201                 /*
 202                  * If 127.0.0.1 matches both allow and deny then allow.
 203                  * Patch from Steve Langasek vorlon@netexpress.net.
 204                  */
 205                 if (deny_list &&
 206                         list_match(deny_list,(char *)client,client_match) &&
 207                                 (!allow_list ||
 208                                 !list_match(allow_list,(char *)client, client_match))) {
 209                         return False;
 210                 }
 211                 return True;
 212         }
 213
 214         /* if theres no deny list and no allow list then allow access */
 215         if ((!deny_list || *deny_list == 0) &&
 216             (!allow_list || *allow_list == 0)) {
 217                 return(True);
 218         }
 219
 220         /* if there is an allow list but no deny list then allow only hosts
 221            on the allow list */
 222         if (!deny_list || *deny_list == 0)
 223                 return(list_match(allow_list,(char *)client,client_match));
 224
 225         /* if theres a deny list but no allow list then allow
 226            all hosts not on the deny list */
 227         if (!allow_list || *allow_list == 0)
 228                 return(!list_match(deny_list,(char *)client,client_match));
 229
 230         /* if there are both types of list then allow all hosts on the
 231            allow list */
 232         if (list_match(allow_list,(char *)client,client_match))
 233                 return (True);
 234
 235         /* if there are both types of list and it's not on the allow then
 236            allow it if its not on the deny */
 237         if (list_match(deny_list,(char *)client,client_match))
 238                 return (False);
 239
 240         return (True);
 241 }
 242
 243 /* return true if access should be allowed */
 244 BOOL allow_access(char **deny_list,char **allow_list,
 245                   const char *cname, const char *caddr)
 246 {
 247         BOOL ret;
 248
 249         char *nc_cname = smb_xstrdup(cname);
 250         char *nc_caddr = smb_xstrdup(caddr);
 251
 252         ret = allow_access_internal(deny_list, allow_list, nc_cname, nc_caddr);
 253
 254         SAFE_FREE(nc_cname);
 255         SAFE_FREE(nc_caddr);
 256         return ret;
 257 }
 258
 259 /* return true if the char* contains ip addrs only.  Used to avoid
 260 gethostbyaddr() calls */
 261 static BOOL only_ipaddrs_in_list(char** list)
 262 {
 263         BOOL            only_ip = True;
 264
 265         if (!list) return True;
 266
 267         for (; *list ; list++)
 268         {
 269                 /* factor out the special strings */
 270                 if (!strcasecmp(*list, "ALL") || !strcasecmp(*list, "FAIL") ||
 271                     !strcasecmp(*list, "EXCEPT"))
 272                 {
 273                         continue;
 274                 }
 275
 276                 if (!is_ipaddress(*list))
 277                 {
 278                         char *p;
 279                         /*
 280                          * if we failed, make sure that it was not because the token
 281                          * was a network/netmask pair.  Only network/netmask pairs
 282                          * have a '/' in them
 283                          */
 284                         if ((p=strchr_m(*list, '/')) == NULL)
 285                         {
 286                                 only_ip = False;
 287                                 DEBUG(3,("only_ipaddrs_in_list: list has non-ip address (%s)\n", *list));
 288                                 break;
 289                         }
 290                 }
 291         }
 292
 293         return only_ip;
 294 }
 295
 296 /* return true if access should be allowed to a service for a socket */
 297 BOOL check_access(int sock, char **allow_list, char **deny_list)
 298 {
 299         BOOL ret = False;
 300         BOOL only_ip = False;
 301
 302         if ((!deny_list || *deny_list==0) && (!allow_list || *allow_list==0))
 303         {
 304                 ret = True;
 305         }
 306
 307         if (!ret)
 308         {
 309                 /* bypass gethostbyaddr() calls if the lists only contain IP addrs */
 310                 if (only_ipaddrs_in_list(allow_list) && only_ipaddrs_in_list(deny_list))
 311                 {
 312                         only_ip = True;
 313                         DEBUG (3, ("check_access: no hostnames in host allow/deny list.\n"));
 314                         ret = allow_access(deny_list,allow_list, "", get_socket_addr(sock));
 315                 }
 316                 else
 317                 {
 318                         DEBUG (3, ("check_access: hostnames in host allow/deny list.\n"));
 319                         ret = allow_access(deny_list,allow_list, get_socket_name(sock),
 320                                            get_socket_addr(sock));
 321                 }
 322
 323                 if (ret)
 324                 {
 325                         DEBUG(2,("Allowed connection from %s (%s)\n",
 326                                  only_ip ? "" : get_socket_name(sock),
 327                                  get_socket_addr(sock)));
 328                 }
 329                 else
 330                 {
 331                         DEBUG(0,("Denied connection from %s (%s)\n",
 332                                  only_ip ? "" : get_socket_name(sock),
 333                                  get_socket_addr(sock)));
 334                 }
 335         }
 336
 337         return(ret);
 338 }