commit febd4ab0e5304a129fb2757949b9a452e7cce162 Author: teor (Tim Wilson-Brown) teor2345@gmail.com Date: Thu Jul 7 16:04:26 2016 +1000
Client & HS make sure every hop in every non-HS path supports ntor
When a client connects to an intro point not in the client's consensus, or a hidden service connects to a rend point not in the hidden service's consensus, we are stuck with using TAP, because there is no ntor link specifier. --- src/or/circuitbuild.c | 116 ++++++++++++++++++++++++++++++++++---------------- src/or/circuitbuild.h | 1 + src/or/onion.c | 4 +- 3 files changed, 82 insertions(+), 39 deletions(-)
diff --git a/src/or/circuitbuild.c b/src/or/circuitbuild.c index d6c5c85..c309a8d 100644 --- a/src/or/circuitbuild.c +++ b/src/or/circuitbuild.c @@ -365,7 +365,7 @@ circuit_rep_hist_note_result(origin_circuit_t *circ) } while (hop!=circ->cpath); }
-/** Return 1 iff at least one node in circ's cpath supports ntor. */ +/** Return 1 iff every node in circ's cpath definitely supports ntor. */ static int circuit_cpath_supports_ntor(const origin_circuit_t *circ) { @@ -373,16 +373,19 @@ circuit_cpath_supports_ntor(const origin_circuit_t *circ)
cpath = head = circ->cpath; do { - if (cpath->extend_info && - !tor_mem_is_zero( - (const char*)cpath->extend_info->curve25519_onion_key.public_key, - CURVE25519_PUBKEY_LEN)) - return 1; + /* if the extend_info is missing, we can't tell if it supports ntor */ + if (!cpath->extend_info) { + return 0; + }
+ /* if the key is blank, it definitely doesn't support ntor */ + if (!extend_info_supports_ntor(cpath->extend_info)) { + return 0; + } cpath = cpath->next; } while (cpath != head);
- return 0; + return 1; }
/** Pick all the entries in our cpath. Stop and return 0 when we're @@ -390,41 +393,61 @@ circuit_cpath_supports_ntor(const origin_circuit_t *circ) static int onion_populate_cpath(origin_circuit_t *circ) { - int n_tries = 0; - const int using_ntor = circuits_can_use_ntor(); + int r = 0;
-#define MAX_POPULATE_ATTEMPTS 32 + /* onion_extend_cpath assumes these are non-NULL */ + tor_assert(circ); + tor_assert(circ->build_state);
- while (1) { - int r = onion_extend_cpath(circ); + while (r == 0) { + r = onion_extend_cpath(circ); if (r < 0) { log_info(LD_CIRC,"Generating cpath hop failed."); return -1; } - if (r == 1) { - /* This circuit doesn't need/shouldn't be forced to have an ntor hop */ - if (circ->build_state->desired_path_len <= 1 || ! using_ntor) - return 0; + }
- /* This circuit has an ntor hop. great! */ - if (circuit_cpath_supports_ntor(circ)) - return 0; + /* The path is complete */ + tor_assert(r == 1);
- /* No node in the circuit supports ntor. Have we already tried too many - * times? */ - if (++n_tries >= MAX_POPULATE_ATTEMPTS) - break; + /* Does every node in this path support ntor? */ + int path_supports_ntor = circuit_cpath_supports_ntor(circ); + + /* We would like every path to support ntor, but we have to allow for some + * edge cases. */ + tor_assert(circuit_get_cpath_len(circ)); + if (circuit_can_use_tap(circ)) { + /* Circuits from clients to intro points, and hidden services to + * rend points do not support ntor, because the hidden service protocol + * does not include ntor onion keys. This is also true for Tor2web clients + * and Single Onion Services. */ + return 0; + }
- /* Clear the path and retry */ - circuit_clear_cpath(circ); + if (circuit_get_cpath_len(circ) == 1) { + /* Allow for bootstrapping: when we're fetching directly from a fallback, + * authority, or bridge, we have no way of knowing its ntor onion key + * before we connect to it. So instead, we try connecting, and end up using + * CREATE_FAST. */ + tor_assert(circ->cpath); + tor_assert(circ->cpath->extend_info); + const node_t *node = node_get_by_id( + circ->cpath->extend_info->identity_digest); + /* If we don't know the node and its descriptor, we must be bootstrapping. + */ + if (!node || !node_has_descriptor(node)) { + return 0; } } - log_warn(LD_CIRC, "I tried for %d times, but I couldn't build a %d-hop " - "circuit with at least one node that supports ntor.", - MAX_POPULATE_ATTEMPTS, - circ->build_state->desired_path_len);
- return -1; + if (BUG(!path_supports_ntor)) { + /* If we're building a multi-hop path, and it's not one of the HS or + * bootstrapping exceptions, and it doesn't support ntor, something has + * gone wrong. */ + return -1; + } + + return 0; }
/** Create and return a new origin circuit. Initialize its purpose and @@ -806,9 +829,7 @@ circuit_pick_create_handshake(uint8_t *cell_type_out, const extend_info_t *ei) { /* XXXX029 Remove support for deciding to use TAP. */ - if (!tor_mem_is_zero((const char*)ei->curve25519_onion_key.public_key, - CURVE25519_PUBKEY_LEN) && - circuits_can_use_ntor()) { + if (extend_info_supports_ntor(ei) && circuits_can_use_ntor()) { *cell_type_out = CELL_CREATE2; *handshake_type_out = ONION_HANDSHAKE_TYPE_NTOR; return; @@ -2054,15 +2075,18 @@ count_acceptable_nodes(smartlist_t *nodes) if (! node->is_running) // log_debug(LD_CIRC,"Nope, the directory says %d is not running.",i); continue; + /* XXX This clause makes us count incorrectly: if AllowInvalidRouters + * allows this node in some places, then we're getting an inaccurate + * count. For now, be conservative and don't count it. But later we + * should try to be smarter. */ if (! node->is_valid) // log_debug(LD_CIRC,"Nope, the directory says %d is not valid.",i); continue; if (! node_has_descriptor(node)) continue; - /* XXX This clause makes us count incorrectly: if AllowInvalidRouters - * allows this node in some places, then we're getting an inaccurate - * count. For now, be conservative and don't count it. But later we - * should try to be smarter. */ + /* The node has a descriptor, so we can just check the ntor key directly */ + if (!node_has_curve25519_onion_key(node)) + continue; ++num; } SMARTLIST_FOREACH_END(node);
@@ -2351,6 +2375,14 @@ extend_info_from_node(const node_t *node, int for_direct_connect) log_warn(LD_CIRC, "Could not choose valid address for %s", node->ri ? node->ri->nickname : node->rs->nickname);
+ /* Every node we connect or extend to must support ntor */ + if (!node_has_curve25519_onion_key(node)) { + log_fn(LOG_PROTOCOL_WARN, LD_CIRC, + "Attempted to create extend_info for a node that does not support " + "ntor: %s", node_describe(node)); + return NULL; + } + if (valid_addr && node->ri) return extend_info_new(node->ri->nickname, node->identity, @@ -2436,3 +2468,13 @@ extend_info_addr_is_allowed(const tor_addr_t *addr) return 0; }
+/* Does ei have a valid ntor key? */ +int +extend_info_supports_ntor(const extend_info_t* ei) +{ + tor_assert(ei); + /* Valid ntor keys have at least one non-zero byte */ + return !tor_mem_is_zero( + (const char*)ei->curve25519_onion_key.public_key, + CURVE25519_PUBKEY_LEN); +} diff --git a/src/or/circuitbuild.h b/src/or/circuitbuild.h index 7f5fd51..73630b4 100644 --- a/src/or/circuitbuild.h +++ b/src/or/circuitbuild.h @@ -54,6 +54,7 @@ extend_info_t *extend_info_from_node(const node_t *r, int for_direct_connect); extend_info_t *extend_info_dup(extend_info_t *info); void extend_info_free(extend_info_t *info); int extend_info_addr_is_allowed(const tor_addr_t *addr); +int extend_info_supports_ntor(const extend_info_t* ei); const node_t *build_state_get_exit_node(cpath_build_state_t *state); const char *build_state_get_exit_nickname(cpath_build_state_t *state);
diff --git a/src/or/onion.c b/src/or/onion.c index 5495074..8a566af 100644 --- a/src/or/onion.c +++ b/src/or/onion.c @@ -11,6 +11,7 @@ **/
#include "or.h" +#include "circuitbuild.h" #include "circuitlist.h" #include "config.h" #include "cpuworker.h" @@ -438,8 +439,7 @@ onion_skin_create(int type, r = CREATE_FAST_LEN; break; case ONION_HANDSHAKE_TYPE_NTOR: - if (tor_mem_is_zero((const char*)node->curve25519_onion_key.public_key, - CURVE25519_PUBKEY_LEN)) + if (!extend_info_supports_ntor(node)) return -1; if (onion_skin_ntor_create((const uint8_t*)node->identity_digest, &node->curve25519_onion_key,