X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/d4095f83496094d7d8649cc412536f69d1cfcb6a..a85c067ba6c6940512cf57ec213277a370d87e70:/src/src/dnsbl.c

diff --git a/src/src/dnsbl.c b/src/src/dnsbl.c
index d3afd5cf8..af80f6be1 100644
--- a/src/src/dnsbl.c
+++ b/src/src/dnsbl.c
@@ -2,9 +2,10 @@
 *     Exim - an Internet mail transport agent    *
 *************************************************/
 
+/* Copyright (c) The Exim Maintainers 2020 - 2022 */
 /* Copyright (c) University of Cambridge 1995 - 2018 */
-/* Copyright (c) The Exim Maintainers 2020 */
 /* See the file NOTICE for conditions of use and distribution. */
+/* SPDX-License-Identifier: GPL-2.0-only */
 
 /* Functions concerned with dnsbls */
 
@@ -74,7 +75,7 @@ tree_node *t;
 dnsbl_cache_block *cb;
 int old_pool = store_pool;
 uschar * query;
-int qlen;
+int qlen, yield;
 
 /* Construct the specific query domainname */
 
@@ -83,7 +84,8 @@ if ((qlen = Ustrlen(query)) >= 256)
   {
   log_write(0, LOG_MAIN|LOG_PANIC, "dnslist query is too long "
     "(ignored): %s...", query);
-  return FAIL;
+  yield = FAIL;
+  goto out;
   }
 
 /* Look for this query in the cache. */
@@ -114,9 +116,9 @@ else
 
   else
     {	/* Set up a tree entry to cache the lookup */
-    t = store_get(sizeof(tree_node) + qlen + 1 + 1, is_tainted(query));
+    t = store_get(sizeof(tree_node) + qlen + 1 + 1, query);
     Ustrcpy(t->name, query);
-    t->data.ptr = cb = store_get(sizeof(dnsbl_cache_block), FALSE);
+    t->data.ptr = cb = store_get(sizeof(dnsbl_cache_block), GET_UNTAINTED);
     (void)tree_insertnode(&dnsbl_cache, t);
     }
 
@@ -247,7 +249,15 @@ if (cb->rc == DNS_SUCCEED)
         ignore IPv6 addresses. The default mask is 0, which always matches.
         We change this only for IPv4 addresses in the list. */
 
-        if (host_aton(da->address, address) == 1) mask = address[0];
+        if (host_aton(da->address, address) == 1)
+	  if ((address[0] & 0xff000000) != 0x7f000000)    /* 127.0.0.0/8 */
+	    log_write(0, LOG_MAIN,
+	      "DNS list lookup for %s at %s returned %s;"
+	      " not in 127.0/8 and discarded",
+	      keydomain, domain, da->address);
+
+	  else
+	    mask = address[0];
 
         /* Scan the returned addresses, skipping any that are IPv6 */
 
@@ -297,7 +307,35 @@ if (cb->rc == DNS_SUCCEED)
           match_type & MT_ALL ? "=" : "",
           bitmask ? '&' : '=', iplist);
         }
-      return FAIL;
+      yield = FAIL;
+      goto out;
+      }
+    }
+
+  /* No address list check; discard any illegal returns and give up if
+  none remain. */
+
+  else
+    {
+    BOOL ok = FALSE;
+    for (da = cb->rhs; da; da = da->next)
+      {
+      int address[4];
+
+      if (  host_aton(da->address, address) == 1		/* ipv4 */
+	 && (address[0] & 0xff000000) == 0x7f000000	/* 127.0.0.0/8 */
+	 )
+	ok = TRUE;
+      else
+	log_write(0, LOG_MAIN,
+	    "DNS list lookup for %s at %s returned %s;"
+	    " not in 127.0/8 and discarded",
+	    keydomain, domain, da->address);
+      }
+    if (!ok)
+      {
+      yield = FAIL;
+      goto out;
       }
     }
 
@@ -308,8 +346,11 @@ if (cb->rc == DNS_SUCCEED)
   there is indeed an A record at the alternate domain. */
 
   if (domain_txt != domain)
-    return one_check_dnsbl(domain_txt, domain_txt, keydomain, prepend, NULL,
+    {
+    yield = one_check_dnsbl(domain_txt, domain_txt, keydomain, prepend, NULL,
       FALSE, match_type, defer_return);
+    goto out;
+    }
 
   /* If there is no alternate domain, look up a TXT record in the main domain
   if it has not previously been cached. */
@@ -325,7 +366,7 @@ if (cb->rc == DNS_SUCCEED)
 	  int len = (rr->data)[0];
 	  if (len > 511) len = 127;
 	  store_pool = POOL_PERM;
-	  cb->text = string_sprintf("%.*s", len, CUS (rr->data+1));
+	  cb->text = string_copyn_taint(CUS (rr->data+1), len, GET_TAINTED);
 	  store_pool = old_pool;
 	  break;
 	  }
@@ -333,7 +374,8 @@ if (cb->rc == DNS_SUCCEED)
 
   dnslist_value = addlist;
   dnslist_text = cb->text;
-  return OK;
+  yield = OK;
+  goto out;
   }
 
 /* There was a problem with the DNS lookup */
@@ -345,7 +387,8 @@ if (cb->rc != DNS_NOMATCH && cb->rc != DNS_NODATA)
     defer_return == OK ?   US"assumed in list" :
     defer_return == FAIL ? US"assumed not in list" :
                             US"returned DEFER");
-  return defer_return;
+  yield = defer_return;
+  goto out;
   }
 
 /* No entry was found in the DNS; continue for next domain */
@@ -357,7 +400,12 @@ HDEBUG(D_dnsbl)
      keydomain, domain);
   }
 
-return FAIL;
+yield = FAIL;
+
+out:
+
+store_free_dns_answer(dnsa);
+return yield;
 }