Merge branch '13605_reduced_exit_squashed'

changes/ticket13605

@@ -0,0 +1,5 @@
+  o Major features (relay):
+    - Implement an option, ReducedExitPolicy, to allow an Tor exit relay
+      operator to use a more reasonable ("reduced") exit policy, rather 
+      than the default one. Closes ticket 13605.  Patch from Neel Chauhan.
+      

doc/tor.1.txt

@@ -1770,7 +1770,13 @@ is non-zero):
        reject *:6346-6429
        reject *:6699
        reject *:6881-6999
-       accept *:*
+       accept *:* +
+ +
+    If you want to use a reduced exit policy rather than the default exit
+    policy, set "ReducedExitPolicy 1". If you want to _replace_ the default
+    exit policy with your custom exit policy, end your exit policy with either
+    a reject *:* or an accept *:*. Otherwise, you’re _augmenting_ (prepending
+    to) the default or reduced exit policy.
 
 [[ExitPolicyDefault]]::
     Since the default exit policy uses accept/reject *, it applies to both
@@ -1794,6 +1800,99 @@ is non-zero):
     to disclose.
     (Default: 0)
 
+[[ReducedExitPolicy] **ReducedExitPolicy** **0**|**1**::
+    If set, use a reduced exit policy rather than the default one. +
+ +
+    The reduced exit policy is an alternative to the default exit policy. It
+    allows as many Internet services as possible while still blocking the
+    majority of TCP ports. Currently, the policy allows approximately 65 ports.
+    This reduces the odds that your node will be used for peer-to-peer
+    applications. +
+ +
+    The reduced exit policy is:
+
+        accept *:20-21
+        accept *:22
+        accept *:23
+        accept *:43
+        accept *:53
+        accept *:79
+        accept *:80-81
+        accept *:88
+        accept *:110
+        accept *:143
+        accept *:194
+        accept *:220
+        accept *:389
+        accept *:443
+        accept *:464
+        accept *:465
+        accept *:531
+        accept *:543-544
+        accept *:554
+        accept *:563
+        accept *:587
+        accept *:636
+        accept *:706
+        accept *:749
+        accept *:873
+        accept *:902-904
+        accept *:981
+        accept *:989-990
+        accept *:991
+        accept *:992
+        accept *:993
+        accept *:994
+        accept *:995
+        accept *:1194
+        accept *:1220
+        accept *:1293
+        accept *:1500
+        accept *:1533
+        accept *:1677
+        accept *:1723
+        accept *:1755
+        accept *:1863
+        accept *:2082
+        accept *:2083
+        accept *:2086-2087
+        accept *:2095-2096
+        accept *:2102-2104
+        accept *:3128
+        accept *:3389
+        accept *:3690
+        accept *:4321
+        accept *:4643
+        accept *:5050
+        accept *:5190
+        accept *:5222-5223
+        accept *:5228
+        accept *:5900
+        accept *:6660-6669
+        accept *:6679
+        accept *:6697
+        accept *:8000
+        accept *:8008
+        accept *:8074
+        accept *:8080
+        accept *:8082
+        accept *:8087-8088
+        accept *:8232-8233
+        accept *:8332-8333
+        accept *:8443
+        accept *:8888
+        accept *:9418
+        accept *:9999
+        accept *:10000
+        accept *:11371
+        accept *:19294
+        accept *:19638
+        accept *:50002
+        accept *:64738
+        reject *:* +
+ +
+    (Default: 0)
+
 [[IPv6Exit]] **IPv6Exit** **0**|**1**::
     If set, and we are an exit node, allow clients to use us for IPv6
     traffic. (Default: 0)

src/or/config.c

@@ -485,6 +485,7 @@ static config_var_t option_vars_[] = {
   V(RendPostPeriod,              INTERVAL, "1 hour"),
   V(RephistTrackTime,            INTERVAL, "24 hours"),
   V(RunAsDaemon,                 BOOL,     "0"),
+  V(ReducedExitPolicy,           BOOL,     "0"),
   OBSOLETE("RunTesting"), // currently unused
   V(Sandbox,                     BOOL,     "0"),
   V(SafeLogging,                 STRING,   "1"),

src/or/or.h

@@ -3674,6 +3674,7 @@ typedef struct {
                                         * interface addresses?
                                         * Includes OutboundBindAddresses and
                                         * configured ports. */
+  int ReducedExitPolicy; /**<Should we use the Reduced Exit Policy? */
   config_line_t *SocksPolicy; /**< Lists of socks policy components */
   config_line_t *DirPolicy; /**< Lists of dir policy components */
   /** Local address to bind outbound sockets */

src/or/policies.c

@@ -81,7 +81,8 @@ static int policies_parse_exit_policy_internal(
                                       const smartlist_t *configured_addresses,
                                       int reject_interface_addresses,
                                       int reject_configured_port_addresses,
-                                      int add_default_policy);
+                                      int add_default_policy,
+                                      int add_reduced_policy);
 
 /** Replace all "private" entries in *<b>policy</b> with their expanded
  * equivalents. */
@@ -1144,7 +1145,7 @@ validate_addr_policies(const or_options_t *options, char **msg)
              "to 1 to disable this warning, and for forward compatibility.",
              options->ExitPolicy == NULL ?
                  " with the default exit policy" : "");
-    if (options->ExitPolicy == NULL) {
+    if (options->ExitPolicy == NULL && options->ReducedExitPolicy == 0) {
       log_warn(LD_CONFIG,
                "In a future version of Tor, ExitRelay 0 may become the "
                "default when no ExitPolicy is given.");
@@ -1877,6 +1878,24 @@ policies_log_first_redundant_entry(const smartlist_t *policy)
   "reject *:563,reject *:1214,reject *:4661-4666,"                  \
   "reject *:6346-6429,reject *:6699,reject *:6881-6999,accept *:*"
 
+#define REDUCED_EXIT_POLICY                                                   \
+  "accept *:20-23,accept *:43,accept *:53,accept *:79-81,accept *:88,"        \
+  "accept *:110,accept *:143,accept *:194,accept *:220,accept *:389,"         \
+  "accept *:443,accept *:464,accept *:465,accept *:531,accept *:543-544,"     \
+  "accept *:554,accept *:563,accept *:587,accept *:636,accept *:706,"         \
+  "accept *:749,accept *:873,accept *:902-904,accept *:981,accept *:989-995," \
+  "accept *:1194,accept *:1220,accept *:1293,accept *:1500,accept *:1533,"    \
+  "accept *:1677,accept *:1723,accept *:1755,accept *:1863,"                  \
+  "accept *:2082-2083,accept *:2086-2087,accept *:2095-2096,"                 \
+  "accept *:2102-2104,accept *:3128,accept *:3389,accept *:3690,"             \
+  "accept *:4321,accept *:4643,accept *:5050,accept *:5190,"                  \
+  "accept *:5222-5223,accept *:5228,accept *:5900,accept *:6660-6669,"        \
+  "accept *:6679,accept *:6697,accept *:8000,accept *:8008,accept *:8074,"    \
+  "accept *:8080,accept *:8082,accept *:8087-8088,accept *:8232-8233,"        \
+  "accept *:8332-8333,accept *:8443,accept *:8888,accept *:9418,"             \
+  "accept *:9999,accept *:10000,accept *:11371,accept *:19294,"               \
+  "accept *:19638,accept *:50002,accept *:64738,reject *:*"
+
 /** Parse the exit policy <b>cfg</b> into the linked list *<b>dest</b>.
  *
  * If <b>ipv6_exit</b> is false, prepend "reject *6:*" to the policy.
@@ -1912,7 +1931,8 @@ policies_parse_exit_policy_internal(config_line_t *cfg,
                                     const smartlist_t *configured_addresses,
                                     int reject_interface_addresses,
                                     int reject_configured_port_addresses,
-                                    int add_default_policy)
+                                    int add_default_policy,
+                                    int add_reduced_policy)
 {
   if (!ipv6_exit) {
     append_exit_policy_string(dest, "reject *6:*");
@@ -1938,7 +1958,9 @@ policies_parse_exit_policy_internal(config_line_t *cfg,
    * effect, and are most likely an error. */
   policies_log_first_redundant_entry(*dest);
 
-  if (add_default_policy) {
+  if (add_reduced_policy) {
+    append_exit_policy_string(dest, REDUCED_EXIT_POLICY);
+  } else if (add_default_policy) {
     append_exit_policy_string(dest, DEFAULT_EXIT_POLICY);
   } else {
     append_exit_policy_string(dest, "reject *4:*");
@@ -1979,13 +2001,15 @@ policies_parse_exit_policy(config_line_t *cfg, smartlist_t **dest,
   int add_default = (options & EXIT_POLICY_ADD_DEFAULT) ? 1 : 0;
   int reject_local_interfaces = (options &
                                  EXIT_POLICY_REJECT_LOCAL_INTERFACES) ? 1 : 0;
+  int add_reduced = (options & EXIT_POLICY_ADD_REDUCED) ? 1 : 0;
 
   return policies_parse_exit_policy_internal(cfg,dest,ipv6_enabled,
                                              reject_private,
                                              configured_addresses,
                                              reject_local_interfaces,
                                              reject_local_interfaces,
-                                             add_default);
+                                             add_default,
+                                             add_reduced);
 }
 
 /** Helper function that adds a copy of addr to a smartlist as long as it is
@@ -2095,7 +2119,10 @@ policies_parse_exit_policy_from_options(const or_options_t *or_options,
   }
 
   if (!or_options->BridgeRelay) {
-    parser_cfg |= EXIT_POLICY_ADD_DEFAULT;
+    if (or_options->ReducedExitPolicy)
+      parser_cfg |= EXIT_POLICY_ADD_REDUCED;
+    else
+      parser_cfg |= EXIT_POLICY_ADD_DEFAULT;
   }
 
   if (or_options->ExitPolicyRejectLocalInterfaces) {

src/or/policies.h

@@ -22,7 +22,8 @@
 #define EXIT_POLICY_REJECT_PRIVATE           (1 << 1)
 #define EXIT_POLICY_ADD_DEFAULT              (1 << 2)
 #define EXIT_POLICY_REJECT_LOCAL_INTERFACES  (1 << 3)
-#define EXIT_POLICY_OPTION_MAX             EXIT_POLICY_REJECT_LOCAL_INTERFACES
+#define EXIT_POLICY_ADD_REDUCED              (1 << 4)
+#define EXIT_POLICY_OPTION_MAX             EXIT_POLICY_ADD_REDUCED
 /* All options set: used for unit testing */
 #define EXIT_POLICY_OPTION_ALL             ((EXIT_POLICY_OPTION_MAX << 1) - 1)