commit 51839f47650463f59bd2cc84da05d5bc535d699d Author: David Goulet dgoulet@torproject.org Date: Fri Feb 2 10:15:28 2018 -0500

geoip: Hook the client history cache into the OOM handler

If the cache is using 20% of our maximum allowed memory, clean 10% of it. Same behavior as the HS descriptor cache.

Closes #25122

Signed-off-by: David Goulet dgoulet@torproject.org --- changes/ticket25122 | 4 +++ src/or/geoip.c | 91 +++++++++++++++++++++++++++++++++++++++++++++++++++++ src/or/geoip.h | 2 ++ src/or/relay.c | 16 ++++++++-- src/test/test.c | 18 +++++++++++ 5 files changed, 128 insertions(+), 3 deletions(-)

diff --git a/changes/ticket25122 b/changes/ticket25122 new file mode 100644 index 000000000..2921811b2 --- /dev/null +++ b/changes/ticket25122 @@ -0,0 +1,4 @@ + o Minor feature (geoip cache): + - Make our OOM handler aware of the geoip client history cache so it + doesn't fill up the memory which is especially important for IPv6 and + our DoS mitigation subsystem. Closes ticket 25122. diff --git a/src/or/geoip.c b/src/or/geoip.c index 00c055bbe..c5e8cdab9 100644 --- a/src/or/geoip.c +++ b/src/or/geoip.c @@ -72,6 +72,10 @@ static smartlist_t *geoip_ipv4_entries = NULL, *geoip_ipv6_entries = NULL; static char geoip_digest[DIGEST_LEN]; static char geoip6_digest[DIGEST_LEN];

+/* Total size in bytes of the geoip client history cache. Used by the OOM + * handler. */ +static size_t geoip_client_history_cache_size; + /** Return the index of the <b>country</b>'s entry in the GeoIP * country list if it is a valid 2-letter country code, otherwise * return -1. */ @@ -526,6 +530,15 @@ HT_PROTOTYPE(clientmap, clientmap_entry_t, node, clientmap_entry_hash, HT_GENERATE2(clientmap, clientmap_entry_t, node, clientmap_entry_hash, clientmap_entries_eq, 0.6, tor_reallocarray_, tor_free_)

+/** Return the size of a client map entry. */ +static inline size_t +clientmap_entry_size(const clientmap_entry_t *ent) +{ + tor_assert(ent); + return (sizeof(clientmap_entry_t) + + (ent->transport_name ? strlen(ent->transport_name) : 0)); +} + /** Free all storage held by <b>ent</b>. */ static void clientmap_entry_free(clientmap_entry_t *ent) @@ -533,6 +546,8 @@ clientmap_entry_free(clientmap_entry_t *ent) if (!ent) return;

+ geoip_client_history_cache_size -= clientmap_entry_size(ent); + tor_free(ent->transport_name); tor_free(ent); } @@ -595,6 +610,7 @@ geoip_note_client_seen(geoip_client_action_t action, ent->transport_name = tor_strdup(transport_name); ent->action = (int)action; HT_INSERT(clientmap, &client_history, ent); + geoip_client_history_cache_size += clientmap_entry_size(ent); } if (now / 60 <= (int)MAX_LAST_SEEN_IN_MINUTES && now >= 0) ent->last_seen_in_minutes = (unsigned)(now/60); @@ -635,6 +651,81 @@ geoip_remove_old_clients(time_t cutoff) &cutoff); }

+/* Cleanup client entries older than the cutoff. Used for the OOM. Return the + * number of bytes freed. If 0 is returned, nothing was freed. */ +static size_t +oom_clean_client_entries(time_t cutoff) +{ + size_t bytes = 0; + clientmap_entry_t **ent, **ent_next; + + for (ent = HT_START(clientmap, &client_history); ent; ent = ent_next) { + clientmap_entry_t *entry = *ent; + if (entry->last_seen_in_minutes < (cutoff / 60)) { + ent_next = HT_NEXT_RMV(clientmap, &client_history, ent); + bytes += clientmap_entry_size(entry); + clientmap_entry_free(entry); + } else { + ent_next = HT_NEXT(clientmap, &client_history, ent); + } + } + return bytes; +} + +/* Below this minimum lifetime, the OOM won't cleanup any entries. */ +#define GEOIP_CLIENT_CACHE_OOM_MIN_CUTOFF (4 * 60 * 60) +/* The OOM moves the cutoff by that much every run. */ +#define GEOIP_CLIENT_CACHE_OOM_STEP (15 * 50) + +/* Cleanup the geoip client history cache called from the OOM handler. Return + * the amount of bytes removed. This can return a value below or above + * min_remove_bytes but will stop as oon as the min_remove_bytes has been + * reached. */ +size_t +geoip_client_cache_handle_oom(time_t now, size_t min_remove_bytes) +{ + time_t k; + size_t bytes_removed = 0; + + /* Our OOM handler called with 0 bytes to remove is a code flow error. */ + tor_assert(min_remove_bytes != 0); + + /* Set k to the initial cutoff of an entry. We then going to move it by step + * to try to remove as much as we can. */ + k = WRITE_STATS_INTERVAL; + + do { + time_t cutoff; + + /* If k has reached the minimum lifetime, we have to stop else we might + * remove every single entries which would be pretty bad for the DoS + * mitigation subsystem if by just filling the geoip cache, it was enough + * to trigger the OOM and clean every single entries. */ + if (k <= GEOIP_CLIENT_CACHE_OOM_MIN_CUTOFF) { + break; + } + + cutoff = now - k; + bytes_removed += oom_clean_client_entries(cutoff); + k -= GEOIP_CLIENT_CACHE_OOM_STEP; + } while (bytes_removed < min_remove_bytes); + + return bytes_removed; +} + +/* Return the total size in bytes of the client history cache. */ +size_t +geoip_client_cache_total_allocation(void) +{ + size_t bytes = 0; + clientmap_entry_t **ent; + + HT_FOREACH(ent, clientmap, &client_history) { + bytes += clientmap_entry_size(*ent); + } + return bytes; +} + /** How many responses are we giving to clients requesting v3 network * statuses? */ static uint32_t ns_v3_responses[GEOIP_NS_RESPONSE_NUM]; diff --git a/src/or/geoip.h b/src/or/geoip.h index 070296dd0..42d0c1cfd 100644 --- a/src/or/geoip.h +++ b/src/or/geoip.h @@ -33,6 +33,8 @@ void geoip_note_client_seen(geoip_client_action_t action, const tor_addr_t *addr, const char *transport_name, time_t now); void geoip_remove_old_clients(time_t cutoff); +size_t geoip_client_cache_total_allocation(void); +size_t geoip_client_cache_handle_oom(time_t now, size_t min_remove_bytes);

void geoip_note_ns_response(geoip_ns_response_t response); char *geoip_get_transport_history(void); diff --git a/src/or/relay.c b/src/or/relay.c index 29f34ca03..22ce76752 100644 --- a/src/or/relay.c +++ b/src/or/relay.c @@ -2469,24 +2469,34 @@ static time_t last_time_under_memory_pressure = 0; STATIC int cell_queues_check_size(void) { + time_t now = time(NULL); size_t alloc = cell_queues_get_total_allocation(); alloc += buf_get_total_allocation(); alloc += tor_zlib_get_total_allocation(); const size_t rend_cache_total = rend_cache_get_total_allocation(); alloc += rend_cache_total; + const size_t geoip_client_cache_total = + geoip_client_cache_total_allocation(); + alloc += geoip_client_cache_total; if (alloc >= get_options()->MaxMemInQueues_low_threshold) { last_time_under_memory_pressure = approx_time(); if (alloc >= get_options()->MaxMemInQueues) { /* If we're spending over 20% of the memory limit on hidden service - * descriptors, free them until we're down to 10%. - */ + * descriptors, free them until we're down to 10%. Do the same for geoip + * client cache. */ if (rend_cache_total > get_options()->MaxMemInQueues / 5) { const size_t bytes_to_remove = rend_cache_total - (size_t)(get_options()->MaxMemInQueues / 10); - rend_cache_clean_v2_descs_as_dir(time(NULL), bytes_to_remove); + rend_cache_clean_v2_descs_as_dir(now, bytes_to_remove); alloc -= rend_cache_total; alloc += rend_cache_get_total_allocation(); } + if (geoip_client_cache_total > get_options()->MaxMemInQueues / 5) { + const size_t bytes_to_remove = + geoip_client_cache_total - + (size_t)(get_options()->MaxMemInQueues / 10); + alloc -= geoip_client_cache_handle_oom(now, bytes_to_remove); + } circuits_handle_oom(alloc); return 1; } diff --git a/src/test/test.c b/src/test/test.c index 9a41b976b..e2fbfd21b 100644 --- a/src/test/test.c +++ b/src/test/test.c @@ -912,6 +912,24 @@ test_geoip(void *arg) tt_str_op(entry_stats_2,OP_EQ, s); tor_free(s);

+ /* Test the OOM handler. Add a client, run the OOM. */ + geoip_entry_stats_init(now); + SET_TEST_ADDRESS(100); + geoip_note_client_seen(GEOIP_CLIENT_CONNECT, &addr, NULL, + now - (12 * 60 * 60)); + /* We've seen this 12 hours ago. Run the OOM, it should clean the entry + * because it is above the minimum cutoff of 4 hours. */ + size_t bytes_removed = geoip_client_cache_handle_oom(now, 1000); + tt_size_op(bytes_removed, OP_GT, 0); + + /* Do it again but this time with an entry with a lower cutoff. */ + geoip_entry_stats_init(now); + SET_TEST_ADDRESS(100); + geoip_note_client_seen(GEOIP_CLIENT_CONNECT, &addr, NULL, + now - (3 * 60 * 60)); + bytes_removed = geoip_client_cache_handle_oom(now, 1000); + tt_size_op(bytes_removed, OP_EQ, 0); + /* Stop collecting entry statistics. */ geoip_entry_stats_term(); get_options_mutable()->EntryStatistics = 0;