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