Merge branch 'map-storage-signature'

Conflicts:
	NEWS.md

4 files changed, 106 insertions, 31 deletions

diff --git a/NEWS.md b/NEWS.md
index 9551b4f..52d2017 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,4 +1,13 @@
-# Changes in catlfish 0.10.1-dev
+# Changes in catlfish 1.0.1-alpha-dev
+
+## Features
+
+- New configuration option 'storage-sign-quorum-size' determines the
+  minimum number of storage nodes successfully storing an entry in
+  order for signing nodes to generate an SCT for it. This prevents a
+  rouge frontend node from sending out an SCT for an entry that will
+  never be merged. An effect of this is that the SCT cache is now
+  mandatory and can not be disabled.
 
 ## Bug fixes
 
diff --git a/doc/system.md b/doc/system.md
new file mode 100644
index 0000000..d5670d5
--- /dev/null
+++ b/doc/system.md
@@ -0,0 +1,41 @@
+# This document
+
+This document contains system documentation of catlfish and plop.
+
+Note that this document is far from complete. Don't draw any
+conclusions from missing topics.
+
+## A certificate chain is being submitted to a frontend node
+
+External HTTP endpoint ct/v1/add-chain [RFC6962 sect 4.1] has one
+input element "chain" which is an array of base64-encoded
+certificates.
+
+The certificate chain is verified and normalised and a "duplicate
+check" is done using plop:get() with a hash over the whole chain. If
+the entry isn't already present in the database or if a matching SCT
+signature is not found in the SCT cache,
+
+- the entry is added -- plop:add()
+- an SCT signature is retrieved from a signing node -- plop:spt\_sig()
+- the SCT signature is added to the SCT cache -- plop:add\_spt\_sig()
+
+If the entry wasn't already present in the database, the entry is
+"committed" by calling plop:commit() which calls internal API
+storage/entrycommitted on all storage nodes.
+
+Internal API storage/entrycommitted passes contents of the
+"timestamp\_signature" header to plop:add\_spt() which
+
+- adds the leafhash to the entryhash key-value store, for retrieval of
+  leafhash given an entry (used in the duplicate check)
+- adds the SPT signature to the SPT cache, i.e. the SCT cache for
+  catlfish
+
+Internal API storage/sendentry returns a "sig" header with
+<KeyName>:<Signature>. The signature is returned by plop:add() to
+catlfish for later use in call to plop:commit().
+
+Internal API signing/sct verifies the signatures in the "signatures"
+header, counts proper signatures against configured storage sign
+quorum and calls its own gen\_server for an SCT signature.
diff --git a/src/catlfish.erl b/src/catlfish.erl
index 4bf1cdf..6d8d430 100644
--- a/src/catlfish.erl
+++ b/src/catlfish.erl
@@ -5,7 +5,7 @@
 -export([add_chain/3, entries/2, entry_and_proof/2]).
 -export([known_roots/0, update_known_roots/0]).
 -export([init_cache_table/0]).
--export([entryhash_from_entry/1, verify_entry/1, verify_entry/2]).
+-export([entryhash_from_entry/1, verify_entry/1, verify_entry/2, spt_data/1]).
 -include_lib("eunit/include/eunit.hrl").
 
 -define(PROTOCOL_VERSION, 0).
@@ -92,28 +92,22 @@ deserialise_entry_type(<<1:16>>) ->
 serialise_signature_type(certificate_timestamp) ->
     <<0:8>>.
 
-calc_sct(TimestampedEntry) ->
+spt_data(DBEntry) ->
+    {_Type, MTLText, _Cert, _Chain} = unpack_entry(DBEntry),
+    MTL = deserialise_mtl(MTLText),
+    TSE = MTL#mtl.entry,
+    sct_data(TSE).
+
+sct_data(TimestampedEntry) ->
+    list_to_binary([<<?PROTOCOL_VERSION:8>>,
+                    serialise_signature_type(certificate_timestamp),
+                    serialise(TimestampedEntry)]).
+
+calc_sct_sig(TimestampedEntry, Signatures) ->
     plop:serialise(
-      plop:spt(list_to_binary([<<?PROTOCOL_VERSION:8>>,
-                               serialise_signature_type(certificate_timestamp),
-                               serialise(TimestampedEntry)]))).
-
-get_sct(Hash, TimestampedEntry) ->
-    case application:get_env(catlfish, sctcache_root_path) of
-        {ok, RootPath} ->
-            case perm:readfile(RootPath, Hash) of
-                Contents when is_binary(Contents) ->
-                    Contents;
-                noentry ->
-                    SCT = calc_sct(TimestampedEntry),
-                    ok = perm:ensurefile_nosync(RootPath, Hash, SCT),
-                    SCT
-            end;
-        _ ->
-            calc_sct(TimestampedEntry)
-    end.
+      plop:spt_sig(sct_data(TimestampedEntry), Signatures)).
 
-add_to_db(Type, LeafCert, CertChain, EntryHash) ->
+create_logentry(Type, LeafCert, CertChain) ->
     EntryType = case Type of
                     normal -> x509_entry;
                     precert -> precert_entry
@@ -125,21 +119,39 @@ add_to_db(Type, LeafCert, CertChain, EntryHash) ->
                              entry = TSE}),
     MTLHash = ht:leaf_hash(MTLText),
     LogEntry = pack_entry(Type, MTLText, LeafCert, CertChain),
-    ok = plop:add(LogEntry, MTLHash, EntryHash),
-    {TSE, MTLHash}.
+    {TSE, MTLHash, LogEntry}.
 
 get_ratelimit_token(Type) ->
     ratelimit:get_token(Type).
 
+
+maybe_add_to_db(Hash, LogEntry, TimestampedEntry, HasEntry) ->
+    CachedSCTSig = plop:get_spt_sig(Hash),
+    HasSig = is_binary(CachedSCTSig),
+
+    case {HasEntry, HasSig} of
+        {true, true} ->
+            %% Entry is present in the database and a signature was
+            %% found in the SCT cache.
+            CachedSCTSig;
+        _ ->
+            %% We don't have the entry or we don't have the SCT in the
+            %% cache.
+            {ok, Signatures} = plop:add(LogEntry, Hash),
+            SCT_sig = calc_sct_sig(TimestampedEntry, Signatures),
+            ok = plop:add_spt_sig(Hash, SCT_sig),
+            SCT_sig
+    end.
+
 -spec add_chain(binary(), [binary()], normal|precert) -> {[{_,_},...]}.
 add_chain(LeafCert, CertChain, Type) ->
     EntryHash = crypto:hash(sha256, [LeafCert | CertChain]),
-    {TimestampedEntry, Hash} =
+    {{TimestampedEntry, Hash, LogEntry}, HasEntry} =
         case plop:get(EntryHash) of
             notfound ->
                 case get_ratelimit_token(add_chain) of
                     ok ->
-                        add_to_db(Type, LeafCert, CertChain, EntryHash);
+                        {create_logentry(Type, LeafCert, CertChain), false};
                     _ ->
                         exit({internalerror, "Rate limiting"})
                 end;
@@ -147,10 +159,18 @@ add_chain(LeafCert, CertChain, Type) ->
                 {_Type, MTLText, _Cert, _Chain} = unpack_entry(DBEntry),
                 MTL = deserialise_mtl(MTLText),
                 MTLText = serialise(MTL),       % verify FIXME: remove
-                {MTL#mtl.entry, MTLHash}
+                {{MTL#mtl.entry, MTLHash, DBEntry}, true}
         end,
 
-    SCT_sig = get_sct(Hash, TimestampedEntry),
+    SCT_sig = maybe_add_to_db(Hash, LogEntry, TimestampedEntry, HasEntry),
+
+    case HasEntry of
+        false ->
+            plop:commit(Hash, EntryHash, SCT_sig);
+        _ ->
+            none
+    end,
+
     {[{sct_version, ?PROTOCOL_VERSION},
       {id, base64:encode(plop:get_logid())},
       {timestamp, TimestampedEntry#timestamped_entry.timestamp},
diff --git a/tools/compileconfig.py b/tools/compileconfig.py
index fd77b90..9973a95 100755
--- a/tools/compileconfig.py
+++ b/tools/compileconfig.py
@@ -257,8 +257,7 @@ def gen_config(nodename, config, localconfig):
     if nodetype & set(["frontendnodes", "mergenodes"]):
         catlfishconfig.append((Symbol("known_roots_path"), localconfig["paths"]["knownroots"]))
     if "frontendnodes" in nodetype:
-        if "sctcaching" in options:
-            catlfishconfig.append((Symbol("sctcache_root_path"), paths["db"] + "sctcache/"))
+        plopconfig.append((Symbol("sptcache_root_path"), paths["db"] + "sctcache"))
         if "ratelimits" in localconfig:
             ratelimits = map(parse_ratelimit, localconfig["ratelimits"].items())
             catlfishconfig.append((Symbol("ratelimits"), ratelimits))
@@ -312,6 +311,8 @@ def gen_config(nodename, config, localconfig):
             (Symbol("sendsth_verified_path"), paths["db"] + "sendsth-verified"),
             (Symbol("entryhash_from_entry"),
              (Symbol("catlfish"), Symbol("entryhash_from_entry"))),
+            (Symbol("spt_data"),
+             (Symbol("catlfish"), Symbol("spt_data"))),
         ]
     if "storagenodes" in nodetype:
         plopconfig += [
@@ -340,12 +341,14 @@ def gen_config(nodename, config, localconfig):
 
     allowed_clients = []
     allowed_servers = []
+    storagenodenames = [node["name"] for node in config["storagenodes"]]
     services = set()
+    storage_sign_quorum = config.get("storage-sign-quorum-size", 0)
 
     if "frontendnodes" in nodetype:
-        storagenodenames = [node["name"] for node in config["storagenodes"]]
         reloadableplopconfig.append((Symbol("storage_nodes"), storagenodeaddresses))
         reloadableplopconfig.append((Symbol("storage_nodes_quorum"), config["storage-quorum-size"]))
+        reloadableplopconfig.append((Symbol("storage_sign_quorum"), storage_sign_quorum))
         services.add(Symbol("ht"))
         allowed_clients += allowed_clients_frontend(mergenodenames, primarymergenodename)
         allowed_clients += allowed_clients_public()
@@ -353,6 +356,7 @@ def gen_config(nodename, config, localconfig):
     if "storagenodes" in nodetype:
         allowed_clients += allowed_clients_storage(frontendnodenames, mergenodenames)
     if "signingnodes" in nodetype:
+        reloadableplopconfig.append((Symbol("storage_sign_quorum"), storage_sign_quorum))
         allowed_clients += allowed_clients_signing(frontendnodenames, primarymergenodename)
         services = [Symbol("sign")]
     if "mergenodes" in nodetype:
@@ -409,6 +413,7 @@ def gen_config(nodename, config, localconfig):
     reloadableplopconfig += [
         (Symbol("allowed_clients"), list(allowed_clients)),
         (Symbol("allowed_servers"), list(allowed_servers)),
+        (Symbol("storage_node_names"), list(storagenodenames)),
         (Symbol("apikeys"), apikeys),
         (Symbol("version"), config["version"]),
     ]