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-rw-r--r--source/lib/access.c389
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diff --git a/source/lib/access.c b/source/lib/access.c
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+/*
+This module is an adaption of code from the tcpd-1.4 package written
+by Wietse Venema, Eindhoven University of Technology, The Netherlands.
+
+The code is used here with permission.
+
+The code has been considerably changed from the original. Bug reports
+should be sent to Andrew.Tridgell@anu.edu.au
+*/
+
+#include "includes.h"
+#include "loadparm.h"
+
+#define ALLOW_PURE_ADDRESSES
+
+extern int DEBUGLEVEL;
+
+#ifndef INADDR_NONE
+#define INADDR_NONE ((unsigned long)~0)
+#endif
+
+
+#define FROM_ADDRLEN (4*3+3+1)
+#define Good True
+#define Bad False
+
+#define CLIENT_MATCH client_match
+
+/* Delimiters for lists of daemons or clients. */
+
+static char sep[] = ", \t";
+
+/* Constants to be used in assignments only, not in comparisons... */
+
+#define YES 1
+#define NO 0
+#define FAIL (-1)
+
+/* Forward declarations. */
+BOOL allow_access(char *deny_list,char *allow_list,struct from_host *client);
+static int list_match(char *list,char *item, int (*match_fn)());
+static int client_match(char *tok,char *item);
+static int string_match(char *tok,char *s);
+static int masked_match(char *tok, char *slash, char *s);
+static int matchname(char *remotehost,struct in_addr addr);
+BOOL fromhost(int sock,struct from_host *f);
+
+
+/* Size of logical line buffer. */
+#define BUFLEN 2048
+
+
+/* return true if access should be allowed to a service*/
+BOOL check_access(int snum)
+{
+ extern int Client;
+ extern struct from_host Client_info;
+ char *denyl,*allowl;
+ BOOL ret = False;
+
+ denyl = lp_hostsdeny(snum);
+ if (denyl) denyl = strdup(denyl);
+
+ allowl = lp_hostsallow(snum);
+ if (allowl) allowl = strdup(allowl);
+
+
+ fromhost(Client,&Client_info);
+
+ if ((!denyl || *denyl==0) && (!allowl || *allowl==0))
+ ret = True;
+
+ if (!ret)
+ {
+ if (!fromhost(Client,&Client_info))
+ DEBUG(0,("ERROR: Can't get from_host info\n"));
+ else
+ {
+ if (allow_access(denyl,allowl,&Client_info))
+ {
+ if (snum >= 0)
+ DEBUG(2,("Allowed connection from %s (%s) to %s\n",
+ Client_info.name,Client_info.addr,
+ lp_servicename(snum)));
+ ret = True;
+ }
+ else
+ if (snum >= 0)
+ DEBUG(0,("Denied connection from %s (%s) to %s\n",
+ Client_info.name,Client_info.addr,
+ lp_servicename(snum)));
+ }
+ }
+
+ if (denyl) free(denyl);
+ if (allowl) free(allowl);
+ return(ret);
+}
+
+
+/* return true if access should be allowed */
+BOOL allow_access(char *deny_list,char *allow_list,struct from_host *client)
+{
+ /* if theres no deny list and no allow list then allow access */
+ if ((!deny_list || *deny_list == 0) && (!allow_list || *allow_list == 0))
+ return(True);
+
+ /* if there is an allow list but no deny list then allow only hosts
+ on the allow list */
+ if (!deny_list || *deny_list == 0)
+ return(list_match(allow_list,(char *)client,CLIENT_MATCH));
+
+ /* if theres a deny list but no allow list then allow
+ all hosts not on the deny list */
+ if (!allow_list || *allow_list == 0)
+ return(!list_match(deny_list,(char *)client,CLIENT_MATCH));
+
+ /* if there are both type of list then allow all hosts on the allow list */
+ if (list_match(allow_list,(char *)client,CLIENT_MATCH))
+ return (True);
+
+ /* if there are both type of list and it's not on the allow then
+ allow it if its not on the deny */
+ if (list_match(deny_list,(char *)client,CLIENT_MATCH))
+ return (False);
+
+ return (True);
+}
+
+/* list_match - match an item against a list of tokens with exceptions */
+/* (All modifications are marked with the initials "jkf") */
+static int list_match(char *list,char *item, int (*match_fn)())
+{
+ char *tok;
+ char *listcopy; /* jkf */
+ int match = NO;
+
+ /*
+ * jkf@soton.ac.uk -- 31 August 1994 -- Stop list_match()
+ * overwriting the list given as its first parameter.
+ */
+
+ /* jkf -- can get called recursively with NULL list */
+ listcopy = (list == 0) ? (char *)0 : strdup(list);
+
+ /*
+ * Process tokens one at a time. We have exhausted all possible matches
+ * when we reach an "EXCEPT" token or the end of the list. If we do find
+ * a match, look for an "EXCEPT" list and recurse to determine whether
+ * the match is affected by any exceptions.
+ */
+
+ for (tok = strtok(listcopy, sep); tok ; tok = strtok(NULL, sep)) {
+ if (strcasecmp(tok, "EXCEPT") == 0) /* EXCEPT: give up */
+ break;
+ if ((match = (*match_fn) (tok, item))) /* YES or FAIL */
+ break;
+ }
+ /* Process exceptions to YES or FAIL matches. */
+
+ if (match != NO) {
+ while ((tok = strtok((char *) 0, sep)) && strcasecmp(tok, "EXCEPT"))
+ /* VOID */ ;
+ if (tok == 0 || list_match((char *) 0, item, match_fn) == NO) {
+ if (listcopy != 0) free(listcopy); /* jkf */
+ return (match);
+ }
+ }
+
+ if (listcopy != 0) free(listcopy); /* jkf */
+ return (NO);
+}
+
+
+/* client_match - match host name and address against token */
+static int client_match(char *tok,char *item)
+{
+ struct from_host *client = (struct from_host *) item;
+ int match;
+
+ /*
+ * Try to match the address first. If that fails, try to match the host
+ * name if available.
+ */
+
+ if ((match = string_match(tok, client->addr)) == 0)
+ if (client->name[0] != 0)
+ match = string_match(tok, client->name);
+ return (match);
+}
+
+/* string_match - match string against token */
+static int string_match(char *tok,char *s)
+{
+ int tok_len;
+ int str_len;
+ char *cut;
+
+ /*
+ * Return YES if a token has the magic value "ALL". Return FAIL if the
+ * token is "FAIL". If the token starts with a "." (domain name), return
+ * YES if it matches the last fields of the string. If the token has the
+ * magic value "LOCAL", return YES if the string does not contain a "."
+ * character. If the token ends on a "." (network number), return YES if
+ * it matches the first fields of the string. If the token begins with a
+ * "@" (netgroup name), return YES if the string is a (host) member of
+ * the netgroup. Return YES if the token fully matches the string. If the
+ * token is a netnumber/netmask pair, return YES if the address is a
+ * member of the specified subnet.
+ */
+
+ if (tok[0] == '.') { /* domain: match last fields */
+ if ((str_len = strlen(s)) > (tok_len = strlen(tok))
+ && strcasecmp(tok, s + str_len - tok_len) == 0)
+ return (YES);
+ } else if (tok[0] == '@') { /* netgroup: look it up */
+#ifdef NETGROUP
+ static char *mydomain = NULL;
+ char *hostname = NULL;
+ BOOL netgroup_ok = False;
+
+ if (!mydomain) yp_get_default_domain(&mydomain);
+
+ if (!(hostname = strdup(s))) {
+ DEBUG(1,("out of memory for strdup!\n"));
+ return NO;
+ }
+
+ netgroup_ok = innetgr(tok + 1, hostname, (char *) 0, mydomain);
+
+ DEBUG(5,("looking for %s of domain %s in netgroup %s gave %s\n",
+ hostname,
+ mydomain,
+ tok+1,
+ BOOLSTR(netgroup_ok)));
+
+#ifdef NETGROUP_INSECURE
+ /* if you really want netgroups that match non qualified names
+ then define NETGROUP_INSECURE. It can, however, be a big
+ security hole */
+ {
+ char *clnt_domain;
+ if (!netgroup_ok && (clnt_domain=strchr(hostname,'.'))) {
+ *clnt_domain++ = '\0';
+ netgroup_ok = innetgr(tok + 1, hostname, (char *) 0, mydomain);
+ }
+ }
+#endif
+
+ free(hostname);
+
+ if (netgroup_ok) return(YES);
+#else
+ DEBUG(0,("access: netgroup support is not configured"));
+ return (NO);
+#endif
+ } else if (strcasecmp(tok, "ALL") == 0) { /* all: match any */
+ return (YES);
+ } else if (strcasecmp(tok, "FAIL") == 0) { /* fail: match any */
+ return (FAIL);
+ } else if (strcasecmp(tok, "LOCAL") == 0) { /* local: no dots */
+ if (strchr(s, '.') == 0 && strcasecmp(s, "unknown") != 0)
+ return (YES);
+ } else if (!strcasecmp(tok, s)) { /* match host name or address */
+ return (YES);
+ } else if (tok[(tok_len = strlen(tok)) - 1] == '.') { /* network */
+ if (strncmp(tok, s, tok_len) == 0)
+ return (YES);
+ } else if ((cut = strchr(tok, '/')) != 0) { /* netnumber/netmask */
+ if (isdigit(s[0]) && masked_match(tok, cut, s))
+ return (YES);
+ }
+ return (NO);
+}
+
+/* masked_match - match address against netnumber/netmask */
+static int masked_match(char *tok, char *slash, char *s)
+{
+ unsigned long net;
+ unsigned long mask;
+ unsigned long addr;
+
+ if ((addr = interpret_addr(s)) == INADDR_NONE)
+ return (NO);
+ *slash = 0;
+ net = interpret_addr(tok);
+ *slash = '/';
+ if (net == INADDR_NONE || (mask = interpret_addr(slash + 1)) == INADDR_NONE) {
+ DEBUG(0,("access: bad net/mask access control: %s", tok));
+ return (NO);
+ }
+ return ((addr & mask) == net);
+}
+
+
+/* fromhost - find out what is at the other end of a socket */
+BOOL fromhost(int sock,struct from_host *f)
+{
+ static struct sockaddr sa;
+ struct sockaddr_in *sockin = (struct sockaddr_in *) (&sa);
+ struct hostent *hp;
+ int length = sizeof(sa);
+ static char addr_buf[FROM_ADDRLEN];
+ static char name_buf[MAXHOSTNAMELEN];
+ BOOL takeAddressAsHostname = False;
+
+ if (getpeername(sock, &sa, &length) < 0)
+ {
+ DEBUG(0,("getpeername failed\n"));
+ return(False);
+ }
+
+ f->sin = sockin;
+ f->addr = strcpy(addr_buf,(char *)inet_ntoa(sockin->sin_addr));
+
+ /* Look up the remote host name. */
+ if ((hp = gethostbyaddr((char *) &sockin->sin_addr,
+ sizeof(sockin->sin_addr),
+ AF_INET)) == 0) {
+ DEBUG(1,("Gethostbyaddr failed for %s\n",addr_buf));
+#ifdef ALLOW_PURE_ADDRESSES
+ takeAddressAsHostname = True;
+#else
+ return(False);
+#endif
+ }
+
+ /* Save the host name. A later gethostbyxxx() call may clobber it. */
+ f->name = StrnCpy(name_buf,
+ takeAddressAsHostname? f->addr : hp->h_name,
+ sizeof(name_buf) - 1);
+
+ /*
+ * Verify that the host name does not belong to someone else. If host
+ * name verification fails, pretend that the host name lookup failed.
+ */
+ if (!takeAddressAsHostname && !matchname(f->name, sockin->sin_addr))
+ {
+ DEBUG(0,("Matchname failed\n"));
+ return(False);
+ }
+
+ return(True);
+}
+
+/* matchname - determine if host name matches IP address */
+static int matchname(char *remotehost,struct in_addr addr)
+{
+ struct hostent *hp;
+ int i;
+
+ if ((hp = Get_Hostbyname(remotehost)) == 0) {
+ DEBUG(0,("Get_Hostbyname(%s): lookup failure", remotehost));
+ return (Bad);
+ }
+
+ /*
+ * Make sure that gethostbyname() returns the "correct" host name.
+ * Unfortunately, gethostbyname("localhost") sometimes yields
+ * "localhost.domain". Since the latter host name comes from the
+ * local DNS, we just have to trust it (all bets are off if the local
+ * DNS is perverted). We always check the address list, though.
+ */
+
+ if (strcasecmp(remotehost, hp->h_name)
+ && strcasecmp(remotehost, "localhost")) {
+ DEBUG(0,("host name/name mismatch: %s != %s",
+ remotehost, hp->h_name));
+ return (Bad);
+ }
+
+ /* Look up the host address in the address list we just got. */
+ for (i = 0; hp->h_addr_list[i]; i++) {
+ if (memcmp(hp->h_addr_list[i], (caddr_t) & addr, sizeof(addr)) == 0)
+ return (Good);
+ }
+
+ /*
+ * The host name does not map to the original host address. Perhaps
+ * someone has compromised a name server. More likely someone botched
+ * it, but that could be dangerous, too.
+ */
+
+ DEBUG(0,("host name/address mismatch: %s != %s",
+ inet_ntoa(addr), hp->h_name));
+ return (Bad);
+}
+
+
generated by cgit (git 2.34.1) at 2024-06-08 22:16:57 +0000