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-bugs@samba.anu.edu.au
   9 */
  10
  11 #include "includes.h"
  12
  13 #define ALLOW_PURE_ADDRESSES
  14
  15 extern int DEBUGLEVEL;
  16
  17 #ifndef INADDR_NONE
  18 #define INADDR_NONE     ((uint32)~0)
  19 #endif
  20
  21
  22 #define Good True
  23 #define Bad False
  24
  25 #define CLIENT_MATCH client_match
  26
  27 /* Delimiters for lists of daemons or clients. */
  28
  29 static char sep[] = ", \t";
  30
  31 /* Constants to be used in assignments only, not in comparisons... */
  32
  33 #define YES             1
  34 #define NO              0
  35 #define FAIL            (-1)
  36
  37 /* Forward declarations. */
  38 static int list_match(char *list,char *item, int (*match_fn)());
  39 static int client_match(char *tok,char *item);
  40 static int string_match(char *tok,char *s);
  41 static int masked_match(char *tok, char *slash, char *s);
  42
  43 /* Size of logical line buffer. */
  44 #define BUFLEN 2048
  45
  46 /* return true if access should be allowed to a service*/
  47 BOOL check_access(int snum)
  48 {
  49   char *denyl,*allowl;
  50   BOOL ret = False;
  51
  52   denyl = lp_hostsdeny(snum);
  53   if (denyl) denyl = strdup(denyl);
  54
  55   allowl = lp_hostsallow(snum);
  56   if (allowl) allowl = strdup(allowl);
  57
  58   if ((!denyl || *denyl==0) && (!allowl || *allowl==0))
  59     ret = True;
  60
  61   if (!ret)
  62     {
  63       if (allow_access(denyl,allowl,client_name(),client_addr()))
  64         {
  65           if (snum >= 0)
  66             DEBUG(2,("Allowed connection from %s (%s) to %s\n",
  67                      client_name(),client_addr(),
  68                      lp_servicename(snum)));
  69           ret = True;
  70         }
  71       else
  72         if (snum >= 0)
  73           DEBUG(0,("Denied connection from %s (%s) to %s\n",
  74                    client_name(),client_addr(),
  75                    lp_servicename(snum)));
  76     }
  77
  78   if (denyl) free(denyl);
  79   if (allowl) free(allowl);
  80   return(ret);
  81 }
  82
  83
  84 /* return true if access should be allowed */
  85 BOOL allow_access(char *deny_list,char *allow_list,char *cname,char *caddr)
  86 {
  87   char *client[2];
  88
  89   client[0] = cname;
  90   client[1] = caddr;
  91
  92   /* if theres no deny list and no allow list then allow access */
  93   if ((!deny_list || *deny_list == 0) && (!allow_list || *allow_list == 0))
  94     return(True);
  95
  96   /* if there is an allow list but no deny list then allow only hosts
  97      on the allow list */
  98   if (!deny_list || *deny_list == 0)
  99     return(list_match(allow_list,(char *)client,CLIENT_MATCH));
 100
 101   /* if theres a deny list but no allow list then allow
 102      all hosts not on the deny list */
 103   if (!allow_list || *allow_list == 0)
 104     return(!list_match(deny_list,(char *)client,CLIENT_MATCH));
 105
 106   /* if there are both type of list then allow all hosts on the allow list */
 107   if (list_match(allow_list,(char *)client,CLIENT_MATCH))
 108     return (True);
 109
 110   /* if there are both type of list and it's not on the allow then
 111      allow it if its not on the deny */
 112   if (list_match(deny_list,(char *)client,CLIENT_MATCH))
 113     return (False);
 114
 115   return (True);
 116 }
 117
 118 /* list_match - match an item against a list of tokens with exceptions */
 119 /* (All modifications are marked with the initials "jkf") */
 120 static int list_match(char *list,char *item, int (*match_fn)())
 121 {
 122     char   *tok;
 123     char   *listcopy;           /* jkf */
 124     int     match = NO;
 125
 126     /*
 127      * jkf@soton.ac.uk -- 31 August 1994 -- Stop list_match()
 128      * overwriting the list given as its first parameter.
 129      */
 130
 131     /* jkf -- can get called recursively with NULL list */
 132     listcopy = (list == 0) ? (char *)0 : strdup(list);
 133
 134     /*
 135      * Process tokens one at a time. We have exhausted all possible matches
 136      * when we reach an "EXCEPT" token or the end of the list. If we do find
 137      * a match, look for an "EXCEPT" list and recurse to determine whether
 138      * the match is affected by any exceptions.
 139      */
 140
 141     for (tok = strtok(listcopy, sep); tok ; tok = strtok(NULL, sep)) {
 142         if (strcasecmp(tok, "EXCEPT") == 0)     /* EXCEPT: give up */
 143             break;
 144         if ((match = (*match_fn) (tok, item)))  /* YES or FAIL */
 145             break;
 146     }
 147     /* Process exceptions to YES or FAIL matches. */
 148
 149     if (match != NO) {
 150         while ((tok = strtok((char *) 0, sep)) && strcasecmp(tok, "EXCEPT"))
 151              /* VOID */ ;
 152         if (tok == 0 || list_match((char *) 0, item, match_fn) == NO) {
 153             if (listcopy != 0) free(listcopy); /* jkf */
 154             return (match);
 155         }
 156     }
 157
 158     if (listcopy != 0) free(listcopy); /* jkf */
 159     return (NO);
 160 }
 161
 162
 163 /* client_match - match host name and address against token */
 164 static int client_match(char *tok,char *item)
 165 {
 166     char **client = (char **)item;
 167     int     match;
 168
 169     /*
 170      * Try to match the address first. If that fails, try to match the host
 171      * name if available.
 172      */
 173
 174     if ((match = string_match(tok, client[1])) == 0)
 175         if (client[0][0] != 0)
 176             match = string_match(tok, client[0]);
 177     return (match);
 178 }
 179
 180 /* string_match - match string against token */
 181 static int string_match(char *tok,char *s)
 182 {
 183     int     tok_len;
 184     int     str_len;
 185     char   *cut;
 186
 187     /*
 188      * Return YES if a token has the magic value "ALL". Return FAIL if the
 189      * token is "FAIL". If the token starts with a "." (domain name), return
 190      * YES if it matches the last fields of the string. If the token has the
 191      * magic value "LOCAL", return YES if the string does not contain a "."
 192      * character. If the token ends on a "." (network number), return YES if
 193      * it matches the first fields of the string. If the token begins with a
 194      * "@" (netgroup name), return YES if the string is a (host) member of
 195      * the netgroup. Return YES if the token fully matches the string. If the
 196      * token is a netnumber/netmask pair, return YES if the address is a
 197      * member of the specified subnet.
 198      */
 199
 200     if (tok[0] == '.') {                        /* domain: match last fields */
 201         if ((str_len = strlen(s)) > (tok_len = strlen(tok))
 202             && strcasecmp(tok, s + str_len - tok_len) == 0)
 203             return (YES);
 204     } else if (tok[0] == '@') {                 /* netgroup: look it up */
 205 #ifdef  NETGROUP
 206       static char *mydomain = NULL;
 207       char *hostname = NULL;
 208       BOOL netgroup_ok = False;
 209
 210       if (!mydomain) yp_get_default_domain(&mydomain);
 211
 212       if (!mydomain) {
 213         DEBUG(0,("Unable to get default yp domain.\n"));
 214         return NO;
 215       }
 216       if (!(hostname = strdup(s))) {
 217         DEBUG(1,("out of memory for strdup!\n"));
 218         return NO;
 219       }
 220
 221       netgroup_ok = innetgr(tok + 1, hostname, (char *) 0, mydomain);
 222
 223       DEBUG(5,("looking for %s of domain %s in netgroup %s gave %s\n",
 224                hostname,
 225                mydomain,
 226                tok+1,
 227                BOOLSTR(netgroup_ok)));
 228
 229 #ifdef NETGROUP_INSECURE
 230       /* if you really want netgroups that match non qualified names
 231          then define NETGROUP_INSECURE. It can, however, be a big
 232          security hole */
 233       {
 234         char        *clnt_domain;
 235         if (!netgroup_ok && (clnt_domain=strchr(hostname,'.'))) {
 236           *clnt_domain++ = '\0';
 237           netgroup_ok = innetgr(tok + 1, hostname, (char *) 0, mydomain);
 238         }
 239       }
 240 #endif
 241
 242       free(hostname);
 243
 244       if (netgroup_ok) return(YES);
 245 #else
 246       DEBUG(0,("access: netgroup support is not configured\n"));
 247       return (NO);
 248 #endif
 249     } else if (strcasecmp(tok, "ALL") == 0) {   /* all: match any */
 250         return (YES);
 251     } else if (strcasecmp(tok, "FAIL") == 0) {  /* fail: match any */
 252         return (FAIL);
 253     } else if (strcasecmp(tok, "LOCAL") == 0) { /* local: no dots */
 254         if (strchr(s, '.') == 0 && strcasecmp(s, "unknown") != 0)
 255             return (YES);
 256     } else if (!strcasecmp(tok, s)) {   /* match host name or address */
 257         return (YES);
 258     } else if (tok[(tok_len = strlen(tok)) - 1] == '.') {       /* network */
 259         if (strncmp(tok, s, tok_len) == 0)
 260             return (YES);
 261     } else if ((cut = strchr(tok, '/')) != 0) { /* netnumber/netmask */
 262         if (isdigit(s[0]) && masked_match(tok, cut, s))
 263             return (YES);
 264     }
 265     return (NO);
 266 }
 267
 268 /* masked_match - match address against netnumber/netmask */
 269 static int masked_match(char *tok, char *slash, char *s)
 270 {
 271   uint32 net;
 272   uint32 mask;
 273   uint32 addr;
 274
 275   if ((addr = interpret_addr(s)) == INADDR_NONE)
 276     return (NO);
 277   *slash = 0;
 278   net = interpret_addr(tok);
 279   *slash = '/';
 280   if (net == INADDR_NONE || (mask = interpret_addr(slash + 1)) == INADDR_NONE) {
 281     DEBUG(0,("access: bad net/mask access control: %s", tok));
 282     return (NO);
 283   }
 284   return ((addr & mask) == net);
 285 }
 286
 287
 288
 289