[tor-commits] [tor/master] Warn and ignore the MyFamily setting if BridgeRelay is also set

[nickm at torproject.org]

commit 281a5e4670bfd4d687f58cf9999666a4d097e35e
Author: Nick Mathewson <nickm at torproject.org>
Date:   Thu May 24 12:39:26 2012 -0400

    Warn and ignore the MyFamily setting if BridgeRelay is also set
    
    Roger explains at
      http://archives.seul.org/tor/talk/Nov-2011/msg00209.html :
    
      "If you list your bridge as part of your family in the relay
      descriptor, then everybody can learn your bridge fingerprint, and
      they can look up your bridge's descriptor (and thus location) at
      the bridge directory authority."
    
    Now, we can't stop relays from listing bridges, but we can warn when
    we notice a bridge listing anybody, which might help some.
    
    This fixes bug 4657; it's a fix on 0.2.0.3-alpha, where bridges were
    first introduced.
---
 changes/bug4657 |    4 ++++
 src/or/config.c |    6 ++++++
 src/or/router.c |    2 +-
 3 files changed, 11 insertions(+), 1 deletions(-)

diff --git a/changes/bug4657 b/changes/bug4657
new file mode 100644
index 0000000..4d9dd7d
--- /dev/null
+++ b/changes/bug4657
@@ -0,0 +1,4 @@
+  o Minor bugfixes:
+    - If the configuration tries to set MyFamily on a bridge, refuse to
+      do so, and warn about the security implications. Fix for bug 4657;
+      bugfix on 0.2.0.3-alpha.
diff --git a/src/or/config.c b/src/or/config.c
index 090aba1..58c76b4 100644
--- a/src/or/config.c
+++ b/src/or/config.c
@@ -3601,6 +3601,12 @@ options_validate(or_options_t *old_options, or_options_t *options,
   if (options->UseEntryGuards && ! options->NumEntryGuards)
     REJECT("Cannot enable UseEntryGuards with NumEntryGuards set to 0");
 
+  if (options->MyFamily && options->BridgeRelay) {
+    log_warn(LD_CONFIG, "Listing a family for a bridge relay is not "
+             "supported: it can reveal bridge fingerprints to censors. "
+             "You should also make sure you aren't listing this bridge's "
+             "fingerprint in any other MyFamily.");
+  }
   if (check_nickname_list(options->MyFamily, "MyFamily", msg))
     return -1;
   for (cl = options->NodeFamilies; cl; cl = cl->next) {
diff --git a/src/or/router.c b/src/or/router.c
index 365e888..1919448 100644
--- a/src/or/router.c
+++ b/src/or/router.c
@@ -1483,7 +1483,7 @@ router_rebuild_descriptor(int force)
   }
   if (authdir_mode(options))
     ri->is_valid = ri->is_named = 1; /* believe in yourself */
-  if (options->MyFamily) {
+  if (options->MyFamily && ! options->BridgeRelay) {
     smartlist_t *family;
     if (!warned_nonexistent_family)
       warned_nonexistent_family = smartlist_create();