Prop#329 Pool: Avoid sharing Guards and Middles between circuits.

Conflux must not use the same Guard for each leg; nor the same middle for each
leg.
This commit is contained in:
Mike Perry 2023-02-03 02:11:10 +00:00
parent 336a24754d
commit 46e473f43e
6 changed files with 193 additions and 18 deletions

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@ -45,6 +45,7 @@
#include "core/or/command.h"
#include "core/or/connection_edge.h"
#include "core/or/connection_or.h"
#include "core/or/conflux_pool.h"
#include "core/or/extendinfo.h"
#include "core/or/onion.h"
#include "core/or/ocirc_event.h"
@ -89,7 +90,8 @@ static int circuit_send_first_onion_skin(origin_circuit_t *circ);
static int circuit_build_no_more_hops(origin_circuit_t *circ);
static int circuit_send_intermediate_onion_skin(origin_circuit_t *circ,
crypt_path_t *hop);
static const node_t *choose_good_middle_server(uint8_t purpose,
static const node_t *choose_good_middle_server(const origin_circuit_t *,
uint8_t purpose,
cpath_build_state_t *state,
crypt_path_t *head,
int cur_len);
@ -2313,7 +2315,8 @@ build_vanguard_middle_exclude_list(uint8_t purpose,
* hop, based on already chosen nodes.
*/
static smartlist_t *
build_middle_exclude_list(uint8_t purpose,
build_middle_exclude_list(const origin_circuit_t *circ,
uint8_t purpose,
cpath_build_state_t *state,
crypt_path_t *head,
int cur_len)
@ -2330,6 +2333,9 @@ build_middle_exclude_list(uint8_t purpose,
excluded = smartlist_new();
// Exclude other middles on pending and built conflux circs
conflux_add_middles_to_exclude_list(circ, excluded);
/* For non-vanguard circuits, add the exit and its family to the exclude list
* (note that the exit/last hop is always chosen first in
* circuit_establish_circuit()). */
@ -2423,7 +2429,8 @@ pick_vanguard_middle_node(const or_options_t *options,
* family, and make sure we don't duplicate any previous nodes or their
* families. */
static const node_t *
choose_good_middle_server(uint8_t purpose,
choose_good_middle_server(const origin_circuit_t * circ,
uint8_t purpose,
cpath_build_state_t *state,
crypt_path_t *head,
int cur_len)
@ -2438,7 +2445,7 @@ choose_good_middle_server(uint8_t purpose,
log_debug(LD_CIRC, "Contemplating intermediate hop #%d: random choice.",
cur_len+1);
excluded = build_middle_exclude_list(purpose, state, head, cur_len);
excluded = build_middle_exclude_list(circ, purpose, state, head, cur_len);
flags |= cpath_build_state_to_crn_flags(state);
flags |= cpath_build_state_to_crn_ipv6_extend_flag(state, cur_len);
@ -2483,7 +2490,8 @@ choose_good_middle_server(uint8_t purpose,
* guard worked or not.
*/
const node_t *
choose_good_entry_server(uint8_t purpose, cpath_build_state_t *state,
choose_good_entry_server(const origin_circuit_t *circ,
uint8_t purpose, cpath_build_state_t *state,
circuit_guard_state_t **guard_state_out)
{
const node_t *choice;
@ -2505,7 +2513,7 @@ choose_good_entry_server(uint8_t purpose, cpath_build_state_t *state,
/* This request is for an entry server to use for a regular circuit,
* and we use entry guard nodes. Just return one of the guard nodes. */
tor_assert(guard_state_out);
return guards_choose_guard(state, purpose, guard_state_out);
return guards_choose_guard(circ, state, purpose, guard_state_out);
}
excluded = smartlist_new();
@ -2551,7 +2559,7 @@ onion_extend_cpath(origin_circuit_t *circ)
if (cur_len == state->desired_path_len - 1) { /* Picking last node */
info = extend_info_dup(state->chosen_exit);
} else if (cur_len == 0) { /* picking first node */
const node_t *r = choose_good_entry_server(purpose, state,
const node_t *r = choose_good_entry_server(circ, purpose, state,
&circ->guard_state);
if (r) {
/* If we're a client, use the preferred address rather than the
@ -2564,7 +2572,7 @@ onion_extend_cpath(origin_circuit_t *circ)
}
} else {
const node_t *r =
choose_good_middle_server(purpose, state, circ->cpath, cur_len);
choose_good_middle_server(circ, purpose, state, circ->cpath, cur_len);
if (r) {
info = extend_info_from_node(r, 0, false);
}

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@ -57,7 +57,8 @@ const char *build_state_get_exit_nickname(cpath_build_state_t *state);
struct circuit_guard_state_t;
const node_t *choose_good_entry_server(uint8_t purpose,
const node_t *choose_good_entry_server(const origin_circuit_t *circ,
uint8_t purpose,
cpath_build_state_t *state,
struct circuit_guard_state_t **guard_state_out);
void circuit_upgrade_circuits_from_guard_wait(void);

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@ -31,6 +31,8 @@
#include "core/or/crypt_path_st.h"
#include "core/or/or_circuit_st.h"
#include "core/or/origin_circuit_st.h"
#include "core/or/extend_info_st.h"
#include "core/or/conflux_st.h"
#include "feature/nodelist/nodelist.h"
@ -1092,6 +1094,127 @@ conflux_launch_leg(const uint8_t *nonce)
return false;
}
/**
* Add the identity digest of the guard nodes of all legs of the conflux
* circuit.
*
* This function checks both pending and linked conflux circuits.
*/
void
conflux_add_guards_to_exclude_list(const origin_circuit_t *orig_circ,
smartlist_t *excluded)
{
tor_assert(orig_circ);
tor_assert(excluded);
/* Ease our lives. */
const circuit_t *circ = TO_CIRCUIT(orig_circ);
/* Ignore if this is not conflux related. */
if (!CIRCUIT_IS_CONFLUX(circ)) {
return;
}
/* When building a circuit, we should not have a conflux object
* ourselves (though one may exist elsewhere). */
tor_assert(!circ->conflux);
/* Getting here without a nonce is a code flow issue. */
if (BUG(!circ->conflux_pending_nonce)) {
return;
}
/* A linked set exists, use it. */
const conflux_t *cfx = linked_pool_get(circ->conflux_pending_nonce, true);
if (cfx) {
CONFLUX_FOR_EACH_LEG_BEGIN(cfx, leg) {
const origin_circuit_t *ocirc = CONST_TO_ORIGIN_CIRCUIT(leg->circ);
smartlist_add(excluded,
tor_memdup(ocirc->cpath->extend_info->identity_digest,
DIGEST_LEN));
} CONFLUX_FOR_EACH_LEG_END(leg);
}
/* An unlinked set might exist for this nonce, if so, add the second hop of
* the existing legs to the exclusion list. */
unlinked_circuits_t *unlinked =
unlinked_pool_get(circ->conflux_pending_nonce, true);
if (unlinked) {
tor_assert(unlinked->is_client);
SMARTLIST_FOREACH_BEGIN(unlinked->legs, leg_t *, leg) {
/* Convert to origin circ and get cpath */
const origin_circuit_t *ocirc = CONST_TO_ORIGIN_CIRCUIT(leg->circ);
smartlist_add(excluded,
tor_memdup(ocirc->cpath->extend_info->identity_digest,
DIGEST_LEN));
} SMARTLIST_FOREACH_END(leg);
}
}
/**
* Add the identity digest of the middle nodes of all legs of the conflux
* circuit.
*
* This function checks both pending and linked conflux circuits.
*
* XXX: The add guard and middle could be merged since it is the exact same
* code except for the cpath position and the identity digest vs node_t in
* the list. We could use an extra param indicating guard or middle. */
void
conflux_add_middles_to_exclude_list(const origin_circuit_t *orig_circ,
smartlist_t *excluded)
{
tor_assert(orig_circ);
tor_assert(excluded);
/* Ease our lives. */
const circuit_t *circ = TO_CIRCUIT(orig_circ);
/* Ignore if this is not conflux related. */
if (!CIRCUIT_IS_CONFLUX(circ)) {
return;
}
/* When building a circuit, we should not have a conflux object
* ourselves (though one may exist elsewhere). */
tor_assert(!circ->conflux);
/* Getting here without a nonce is a code flow issue. */
if (BUG(!circ->conflux_pending_nonce)) {
return;
}
/* A linked set exists, use it. */
const conflux_t *cfx = linked_pool_get(circ->conflux_pending_nonce, true);
if (cfx) {
CONFLUX_FOR_EACH_LEG_BEGIN(cfx, leg) {
const origin_circuit_t *ocirc = CONST_TO_ORIGIN_CIRCUIT(leg->circ);
node_t *node = node_get_mutable_by_id(
ocirc->cpath->next->extend_info->identity_digest);
if (node) {
smartlist_add(excluded, node);
}
} CONFLUX_FOR_EACH_LEG_END(leg);
}
/* An unlinked set might exist for this nonce, if so, add the second hop of
* the existing legs to the exclusion list. */
unlinked_circuits_t *unlinked =
unlinked_pool_get(circ->conflux_pending_nonce, true);
if (unlinked) {
tor_assert(unlinked->is_client);
SMARTLIST_FOREACH_BEGIN(unlinked->legs, leg_t *, leg) {
/* Convert to origin circ and get cpath */
const origin_circuit_t *ocirc = CONST_TO_ORIGIN_CIRCUIT(leg->circ);
node_t *node = node_get_mutable_by_id(
ocirc->cpath->next->extend_info->identity_digest);
if (node) {
smartlist_add(excluded, node);
}
} SMARTLIST_FOREACH_END(leg);
}
}
/** The given circuit is conflux pending and has closed. This deletes the leg
* from the set, attempt to finalize it and relaunch a new leg. If the set is
* empty after removing this leg, it is deleted. */

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@ -21,6 +21,11 @@ void conflux_predict_new(time_t now);
bool conflux_launch_leg(const uint8_t *nonce);
void conflux_add_guards_to_exclude_list(const origin_circuit_t *circ,
smartlist_t *excluded);
void conflux_add_middles_to_exclude_list(const origin_circuit_t *circ,
smartlist_t *excluded);
void conflux_circuit_has_closed(circuit_t *circ);
void conflux_circuit_has_opened(origin_circuit_t *orig_circ);
void conflux_circuit_about_to_free(circuit_t *circ);

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@ -126,6 +126,7 @@
#include "core/or/circuitlist.h"
#include "core/or/circuitstats.h"
#include "core/or/circuituse.h"
#include "core/or/conflux_pool.h"
#include "core/or/policies.h"
#include "feature/client/bridges.h"
#include "feature/client/circpathbias.h"
@ -151,6 +152,8 @@
#include "core/or/origin_circuit_st.h"
#include "app/config/or_state_st.h"
#include "core/or/conflux_util.h"
/** A list of existing guard selection contexts. */
static smartlist_t *guard_contexts = NULL;
/** The currently enabled guard selection context. */
@ -1588,6 +1591,19 @@ guard_create_exit_restriction(const uint8_t *exit_id)
return rst;
}
/* Allocate and return a new exit guard restriction that excludes all current
* and pending conflux guards */
STATIC entry_guard_restriction_t *
guard_create_conflux_restriction(const origin_circuit_t *circ)
{
entry_guard_restriction_t *rst = NULL;
rst = tor_malloc_zero(sizeof(entry_guard_restriction_t));
rst->type = RST_EXCL_LIST;
rst->excluded = smartlist_new();
conflux_add_guards_to_exclude_list(circ, rst->excluded);
return rst;
}
/** If we have fewer than this many possible usable guards, don't set
* MD-availability-based restrictions: we might denylist all of them. */
#define MIN_GUARDS_FOR_MD_RESTRICTION 10
@ -1680,6 +1696,8 @@ entry_guard_obeys_restriction(const entry_guard_t *guard,
return guard_obeys_exit_restriction(guard, rst);
} else if (rst->type == RST_OUTDATED_MD_DIRSERVER) {
return guard_obeys_md_dirserver_restriction(guard);
} else if (rst->type == RST_EXCL_LIST) {
return !smartlist_contains_digest(rst->excluded, guard->identity);
}
tor_assert_nonfatal_unreached();
@ -2427,6 +2445,11 @@ entry_guard_has_higher_priority(entry_guard_t *a, entry_guard_t *b)
STATIC void
entry_guard_restriction_free_(entry_guard_restriction_t *rst)
{
if (rst && rst->excluded) {
SMARTLIST_FOREACH(rst->excluded, void *, g,
tor_free(g));
smartlist_free(rst->excluded);
}
tor_free(rst);
}
@ -3780,7 +3803,8 @@ guards_update_all(void)
/** Helper: pick a guard for a circuit, with whatever algorithm is
used. */
const node_t *
guards_choose_guard(cpath_build_state_t *state,
guards_choose_guard(const origin_circuit_t *circ,
cpath_build_state_t *state,
uint8_t purpose,
circuit_guard_state_t **guard_state_out)
{
@ -3788,14 +3812,18 @@ guards_choose_guard(cpath_build_state_t *state,
const uint8_t *exit_id = NULL;
entry_guard_restriction_t *rst = NULL;
/* Only apply restrictions if we have a specific exit node in mind, and only
* if we are not doing vanguard circuits: we don't want to apply guard
* restrictions to vanguard circuits. */
if (state && !circuit_should_use_vanguards(purpose) &&
/* If we this is a conflux circuit, build an exclusion list for it. */
if (CIRCUIT_IS_CONFLUX(TO_CIRCUIT(circ))) {
rst = guard_create_conflux_restriction(circ);
/* Don't allow connecting back to the exit if there is one */
if (state && (exit_id = build_state_get_exit_rsa_id(state))) {
/* add the exit_id to the excluded list */
smartlist_add(rst->excluded, tor_memdup(exit_id, DIGEST_LEN));
}
} else if (state && !circuit_should_use_vanguards(purpose) &&
(exit_id = build_state_get_exit_rsa_id(state))) {
/* We're building to a targeted exit node, so that node can't be
* chosen as our guard for this circuit. Remember that fact in a
* restriction. */
* chosen as our guard for this circuit, unless we're vanguards. */
rst = guard_create_exit_restriction(exit_id);
tor_assert(rst);
}

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@ -294,7 +294,9 @@ typedef enum guard_restriction_type_t {
/* Don't pick the same guard node as our exit node (or its family) */
RST_EXIT_NODE = 0,
/* Don't pick dirguards that have previously shown to be outdated */
RST_OUTDATED_MD_DIRSERVER = 1
RST_OUTDATED_MD_DIRSERVER = 1,
/* Don't pick guards if they are in the exclusion list */
RST_EXCL_LIST = 2,
} guard_restriction_type_t;
/**
@ -312,6 +314,10 @@ struct entry_guard_restriction_t {
* digest must not equal this; and it must not be in the same family as any
* node with this digest. */
uint8_t exclude_id[DIGEST_LEN];
/* In the case of RST_EXCL_LIST, any identity digests in this list
* must not be used. */
smartlist_t *excluded;
};
/**
@ -337,7 +343,8 @@ struct circuit_guard_state_t {
/* Common entry points for old and new guard code */
int guards_update_all(void);
const node_t *guards_choose_guard(cpath_build_state_t *state,
const node_t *guards_choose_guard(const origin_circuit_t *circ,
cpath_build_state_t *state,
uint8_t purpose,
circuit_guard_state_t **guard_state_out);
const node_t *guards_choose_dirguard(uint8_t dir_purpose,
@ -597,6 +604,9 @@ STATIC entry_guard_restriction_t *guard_create_exit_restriction(
STATIC entry_guard_restriction_t *guard_create_dirserver_md_restriction(void);
STATIC entry_guard_restriction_t * guard_create_conflux_restriction(
const origin_circuit_t *circ);
STATIC void entry_guard_restriction_free_(entry_guard_restriction_t *rst);
#define entry_guard_restriction_free(rst) \
FREE_AND_NULL(entry_guard_restriction_t, \