commit f26950fa7a077de4b6a9329af397fce74182b1e5 Author: David Goulet dgoulet@torproject.org Date: Wed Jan 27 21:49:56 2021 -0500
relay: Add bloomfiter of relay address + {OR|Dir}Port
In order to deny re-entry in the network, we now keep a bloomfilter of relay ORPort + address and authorities ORPort + address and DirPort + address combinations.
So when an Exit stream is handled, we deny anything connecting back into the network on the ORPorts for relays and on the ORPort+DirPort for the authorities.
Related to #2667
Signed-off-by: David Goulet dgoulet@torproject.org --- src/core/or/address_set.c | 74 +++++++++++++++++++++++++++++++++++ src/core/or/address_set.h | 20 +++++++++- src/feature/nodelist/dirlist.c | 36 +++++++++++++++++ src/feature/nodelist/dirlist.h | 2 + src/feature/nodelist/nodelist.c | 87 +++++++++++++++++++++++++++++++++++------ src/feature/nodelist/nodelist.h | 4 ++ 6 files changed, 209 insertions(+), 14 deletions(-)
diff --git a/src/core/or/address_set.c b/src/core/or/address_set.c index 758fba4aac..c2daf89dde 100644 --- a/src/core/or/address_set.c +++ b/src/core/or/address_set.c @@ -69,3 +69,77 @@ address_set_probably_contains(const address_set_t *set, { return bloomfilt_probably_contains(set, addr); } + +/* Length of the item is an address (IPv4 or IPv6) and a 2 byte port. We use + * 16 bytes for the address here (IPv6) since we do not know which family + * the given address in the item thus in the case of IPv4, the extra bytes + * are simply zeroes to accomodate. */ +#define BLOOMFILT_ADDR_PORT_ITEM_LEN (16 + sizeof(uint16_t)) + +/** Build an item for the bloomfilter consisting of an address and port pair. + * + * If the given address is _not_ AF_INET or AF_INET6, then the item is an + * array of 0s. + * + * Return a pointer to a static buffer containing the item. Next call to this + * function invalidates its previous content. */ +static const uint8_t * +build_addr_port_item(const tor_addr_t *addr, const uint16_t port) +{ + static uint8_t data[BLOOMFILT_ADDR_PORT_ITEM_LEN]; + + memset(data, 0, sizeof(data)); + switch (tor_addr_family(addr)) { + case AF_INET: + memcpy(data, &addr->addr.in_addr.s_addr, 4); + break; + case AF_INET6: + memcpy(data, &addr->addr.in6_addr.s6_addr, 16); + break; + case AF_UNSPEC: + /* Leave the 0. */ + break; + default: + /* LCOV_EXCL_START */ + tor_fragile_assert(); + /* LCOV_EXCL_STOP */ + } + + memcpy(data + 16, &port, sizeof(port)); + return data; +} + +/** Return a hash value for the given item that the bloomfilter will use. */ +static uint64_t +bloomfilt_addr_port_hash(const struct sipkey *key, + const void *item) +{ + return siphash24(item, BLOOMFILT_ADDR_PORT_ITEM_LEN, key); +} + +/** Allocate and return an addr_port_set_t, suitable for holding up to + * max_address_guess distinct values. */ +addr_port_set_t * +addr_port_set_new(int max_addresses_guess) +{ + uint8_t k[BLOOMFILT_KEY_LEN]; + crypto_rand((void*)k, sizeof(k)); + return bloomfilt_new(max_addresses_guess, bloomfilt_addr_port_hash, k); +} + +/** Add an address and port pair to the given set. */ +void +addr_port_set_add(addr_port_set_t *set, const tor_addr_t *addr, uint16_t port) +{ + bloomfilt_add(set, build_addr_port_item(addr, port)); +} + +/** Return true if the given address and port pair are in the set. Of course, + * this is a bloomfilter and thus in rare occasion, a false positive happens + * thus the "probably". */ +bool +addr_port_set_probably_contains(const addr_port_set_t *set, + const tor_addr_t *addr, uint16_t port) +{ + return !!bloomfilt_probably_contains(set, build_addr_port_item(addr, port)); +} diff --git a/src/core/or/address_set.h b/src/core/or/address_set.h index 7a9e71628e..a7b7cb3f78 100644 --- a/src/core/or/address_set.h +++ b/src/core/or/address_set.h @@ -13,13 +13,14 @@ #include "lib/cc/torint.h" #include "lib/container/bloomfilt.h"
+struct tor_addr_t; + /** * An address_set_t represents a set of tor_addr_t values. The implementation * is probabilistic: false negatives cannot occur but false positives are * possible. */ typedef struct bloomfilt_t address_set_t; -struct tor_addr_t;
address_set_t *address_set_new(int max_addresses_guess); #define address_set_free(set) bloomfilt_free(set) @@ -28,4 +29,19 @@ void address_set_add_ipv4h(address_set_t *set, uint32_t addr); int address_set_probably_contains(const address_set_t *set, const struct tor_addr_t *addr);
-#endif +/** + * An addr_port_set_t represents a set of tor_addr_t values with a uint16_t + * port value. The implementation is probabilistic: false negatives cannot + * occur but false positives are possible. + */ +typedef struct bloomfilt_t addr_port_set_t; + +addr_port_set_t *addr_port_set_new(int max_addresses_guess); +#define addr_port_set_free(s) bloomfilt_free(s) +void addr_port_set_add(addr_port_set_t *set, + const struct tor_addr_t *addr, uint16_t port); +bool addr_port_set_probably_contains(const addr_port_set_t *set, + const struct tor_addr_t *addr, + uint16_t port); + +#endif /* !defined(TOR_ADDRESS_SET_H) */ diff --git a/src/feature/nodelist/dirlist.c b/src/feature/nodelist/dirlist.c index 93baa6e4e0..25f769dd5a 100644 --- a/src/feature/nodelist/dirlist.c +++ b/src/feature/nodelist/dirlist.c @@ -49,6 +49,42 @@ static smartlist_t *trusted_dir_servers = NULL; * and all fallback directory servers. */ static smartlist_t *fallback_dir_servers = NULL;
+/** Helper: From a given trusted directory entry, add the v4 or/and v6 address + * to the nodelist address set. */ +static void +add_trusted_dir_to_nodelist_addr_set(const dir_server_t *dir) +{ + tor_addr_t tmp_addr; + + tor_assert(dir); + tor_assert(dir->is_authority); + + /* Add IPv4 and then IPv6 if applicable. For authorities, we add the ORPort + * and DirPort so re-entry into the network back to them is not possible. */ + tor_addr_from_ipv4h(&tmp_addr, dir->addr); + nodelist_add_addr_to_address_set(&tmp_addr, dir->or_port, dir->dir_port); + if (!tor_addr_is_null(&dir->ipv6_addr)) { + /* IPv6 DirPort is not a thing yet for authorities. */ + nodelist_add_addr_to_address_set(&dir->ipv6_addr, dir->ipv6_orport, 0); + } +} + +/** Go over the trusted directory server list and add their address(es) to the + * nodelist address set. This is called every time a new consensus is set. */ +void +dirlist_add_trusted_dir_addresses(void) +{ + if (!trusted_dir_servers) { + return; + } + + SMARTLIST_FOREACH_BEGIN(trusted_dir_servers, const dir_server_t *, ent) { + if (ent->is_authority) { + add_trusted_dir_to_nodelist_addr_set(ent); + } + } SMARTLIST_FOREACH_END(ent); +} + /** Return the number of directory authorities whose type matches some bit set * in <b>type</b> */ int diff --git a/src/feature/nodelist/dirlist.h b/src/feature/nodelist/dirlist.h index 9fabd0a44a..9354769bcf 100644 --- a/src/feature/nodelist/dirlist.h +++ b/src/feature/nodelist/dirlist.h @@ -44,4 +44,6 @@ void dir_server_add(dir_server_t *ent); void clear_dir_servers(void); void dirlist_free_all(void);
+void dirlist_add_trusted_dir_addresses(void); + #endif diff --git a/src/feature/nodelist/nodelist.c b/src/feature/nodelist/nodelist.c index 8974d95db6..9d553ce1f5 100644 --- a/src/feature/nodelist/nodelist.c +++ b/src/feature/nodelist/nodelist.c @@ -134,6 +134,10 @@ typedef struct nodelist_t { /* Set of addresses that belong to nodes we believe in. */ address_set_t *node_addrs;
+ /* Set of addresses + port that belong to nodes we know and that we don't + * allow network re-entry towards them. */ + addr_port_set_t *reentry_set; + /* The valid-after time of the last live consensus that initialized the * nodelist. We use this to detect outdated nodelists that need to be * rebuilt using a newer consensus. */ @@ -446,27 +450,61 @@ node_addrs_changed(node_t *node) static void node_add_to_address_set(const node_t *node) { - if (!the_nodelist || !the_nodelist->node_addrs) + tor_addr_t tmp_addr; + + if (!the_nodelist || + !the_nodelist->node_addrs || !the_nodelist->reentry_set) return;
- /* These various address sources can be redundant, but it's likely faster - * to add them all than to compare them all for equality. */ + /* These various address sources can be redundant, but it's likely faster to + * add them all than to compare them all for equality. + * + * For relays, we only add the ORPort in the addr+port set since we want to + * allow re-entry into the network to the DirPort so the self reachability + * test succeeds and thus the 0 value for the DirPort. */
if (node->rs) { - if (node->rs->addr) - address_set_add_ipv4h(the_nodelist->node_addrs, node->rs->addr); + if (node->rs->addr) { + tor_addr_from_ipv4h(&tmp_addr, node->rs->addr); + nodelist_add_addr_to_address_set(&tmp_addr, node->rs->or_port, 0); + } if (!tor_addr_is_null(&node->rs->ipv6_addr)) - address_set_add(the_nodelist->node_addrs, &node->rs->ipv6_addr); + nodelist_add_addr_to_address_set(&node->rs->ipv6_addr, + node->rs->ipv6_orport, 0); } if (node->ri) { - if (node->ri->addr) - address_set_add_ipv4h(the_nodelist->node_addrs, node->ri->addr); + if (node->ri->addr) { + tor_addr_from_ipv4h(&tmp_addr, node->ri->addr); + nodelist_add_addr_to_address_set(&tmp_addr, node->ri->or_port, 0); + } if (!tor_addr_is_null(&node->ri->ipv6_addr)) - address_set_add(the_nodelist->node_addrs, &node->ri->ipv6_addr); + nodelist_add_addr_to_address_set(&node->ri->ipv6_addr, + node->ri->ipv6_orport, 0); } if (node->md) { if (!tor_addr_is_null(&node->md->ipv6_addr)) - address_set_add(the_nodelist->node_addrs, &node->md->ipv6_addr); + nodelist_add_addr_to_address_set(&node->md->ipv6_addr, + node->md->ipv6_orport, 0); + } +} + +/** Add the given address into the nodelist address set. */ +void +nodelist_add_addr_to_address_set(const tor_addr_t *addr, + uint16_t or_port, uint16_t dir_port) +{ + if (BUG(!addr) || tor_addr_is_null(addr) || + (!tor_addr_is_v4(addr) && tor_addr_family(addr) != AF_INET6) || + !the_nodelist || !the_nodelist->node_addrs || + !the_nodelist->reentry_set) { + return; + } + address_set_add(the_nodelist->node_addrs, addr); + if (or_port != 0) { + addr_port_set_add(the_nodelist->reentry_set, addr, or_port); + } + if (dir_port != 0) { + addr_port_set_add(the_nodelist->reentry_set, addr, dir_port); } }
@@ -484,6 +522,21 @@ nodelist_probably_contains_address(const tor_addr_t *addr) return address_set_probably_contains(the_nodelist->node_addrs, addr); }
+/** Return true if <b>addr</b> is the address of some node in the nodelist and + * corresponds also to the given port. If not, probably return false. */ +bool +nodelist_reentry_probably_contains(const tor_addr_t *addr, uint16_t port) +{ + if (BUG(!addr) || BUG(!port)) + return false; + + if (!the_nodelist || !the_nodelist->reentry_set) + return false; + + return addr_port_set_probably_contains(the_nodelist->reentry_set, + addr, port); +} + /** Add <b>ri</b> to an appropriate node in the nodelist. If we replace an * old routerinfo, and <b>ri_old_out</b> is not NULL, set *<b>ri_old_out</b> * to the previous routerinfo. @@ -612,10 +665,15 @@ nodelist_set_consensus(networkstatus_t *ns) node->rs = NULL);
/* Conservatively estimate that every node will have 2 addresses. */ - const int estimated_addresses = smartlist_len(ns->routerstatus_list) * - get_estimated_address_per_node(); + int estimated_addresses = smartlist_len(ns->routerstatus_list) * + get_estimated_address_per_node(); + estimated_addresses += (get_n_authorities(V3_DIRINFO | BRIDGE_DIRINFO) * + get_estimated_address_per_node()); address_set_free(the_nodelist->node_addrs); + addr_port_set_free(the_nodelist->reentry_set); the_nodelist->node_addrs = address_set_new(estimated_addresses); + /* Times two here is for both the ORPort and DirPort. */ + the_nodelist->reentry_set = addr_port_set_new(estimated_addresses * 2);
SMARTLIST_FOREACH_BEGIN(ns->routerstatus_list, routerstatus_t *, rs) { node_t *node = node_get_or_create(rs->identity_digest); @@ -664,6 +722,9 @@ nodelist_set_consensus(networkstatus_t *ns) SMARTLIST_FOREACH_BEGIN(the_nodelist->nodes, node_t *, node) { node_add_to_address_set(node); } SMARTLIST_FOREACH_END(node); + /* Then, add all trusted configured directories. Some might not be in the + * consensus so make sure we know them. */ + dirlist_add_trusted_dir_addresses();
if (! authdir) { SMARTLIST_FOREACH_BEGIN(the_nodelist->nodes, node_t *, node) { @@ -839,6 +900,8 @@ nodelist_free_all(void)
address_set_free(the_nodelist->node_addrs); the_nodelist->node_addrs = NULL; + addr_port_set_free(the_nodelist->reentry_set); + the_nodelist->reentry_set = NULL;
tor_free(the_nodelist); } diff --git a/src/feature/nodelist/nodelist.h b/src/feature/nodelist/nodelist.h index c430f497d5..4c4ee6fe83 100644 --- a/src/feature/nodelist/nodelist.h +++ b/src/feature/nodelist/nodelist.h @@ -35,6 +35,10 @@ node_t *nodelist_add_microdesc(microdesc_t *md); void nodelist_set_consensus(networkstatus_t *ns); void nodelist_ensure_freshness(networkstatus_t *ns); int nodelist_probably_contains_address(const tor_addr_t *addr); +bool nodelist_reentry_probably_contains(const tor_addr_t *addr, + uint16_t port); +void nodelist_add_addr_to_address_set(const tor_addr_t *addr, + uint16_t or_port, uint16_t dir_port);
void nodelist_remove_microdesc(const char *identity_digest, microdesc_t *md); void nodelist_remove_routerinfo(routerinfo_t *ri);