commit b8bef61a8f7d9b24064be8f2b6a0c6fca58c042d Author: AltF4 altf4@phx2600.org Date: Wed Feb 9 22:03:53 2011 -0700

Fix time skew values from untrusted sources

Now when we receive a large time skew from a source which isn't a trusted dir, we go contact a trusted dir to trigger a NETINFO cell. --- src/or/command.c | 32 ++++++++++++++++++++++++++++---- 1 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/src/or/command.c b/src/or/command.c index 00d9af3..abe755e 100644 --- a/src/or/command.c +++ b/src/or/command.c @@ -44,6 +44,8 @@ uint64_t stats_n_destroy_cells_processed = 0; uint64_t stats_n_versions_cells_processed = 0; /** How many CELL_NETINFO cells have we received, ever? */ uint64_t stats_n_netinfo_cells_processed = 0; +/** Have we received skew info from a NETINFO cell from a trusted dir, ever? */ +static int received_skew_from_trusted_dir = 0;

/* These are the main functions for processing cells */ static void command_process_create_cell(cell_t *cell, or_connection_t *conn); @@ -617,15 +619,19 @@ command_process_netinfo_cell(cell_t *cell, or_connection_t *conn) }

/* Act on apparent skew. */ - /** Warn when we get a netinfo skew with at least this value. */ + /** Warn when we get a netinfo skew with at least this value. + Ignore if we've already recieved skew info from a trusted dir */ #define NETINFO_NOTICE_SKEW 3600 if (labs(apparent_skew) > NETINFO_NOTICE_SKEW && - router_get_by_digest(conn->identity_digest)) { + router_get_by_digest(conn->identity_digest) && + !received_skew_from_trusted_dir) { char dbuf[64]; int severity; /*XXXX be smarter about when everybody says we are skewed. */ - if (router_digest_is_trusted_dir(conn->identity_digest)) + if (router_digest_is_trusted_dir(conn->identity_digest)) { severity = LOG_WARN; + received_skew_from_trusted_dir = 1; + } else severity = LOG_INFO; format_time_interval(dbuf, sizeof(dbuf), apparent_skew); @@ -636,11 +642,29 @@ command_process_netinfo_cell(cell_t *cell, or_connection_t *conn) conn->_base.address, (int)conn->_base.port, apparent_skew>0 ? "ahead" : "behind", dbuf, apparent_skew>0 ? "behind" : "ahead"); - if (severity == LOG_WARN) /* only tell the controller if an authority */ + if (severity == LOG_WARN) { /* only tell the controller if an authority */ control_event_general_status(LOG_WARN, "CLOCK_SKEW SKEW=%ld SOURCE=OR:%s:%d", apparent_skew, conn->_base.address, conn->_base.port); + } + else { /* Connect to a trusted dir to trigger a NETINFO cell*/ + routerstatus_t *any_trusted_dir = + router_pick_trusteddirserver(NO_AUTHORITY, 0); + const tor_addr_t trusted_dir_addr; + tor_addr_from_ipv4n(&trusted_dir_addr, any_trusted_dir->addr); + connection_or_connect(&trusted_dir_addr, + any_trusted_dir->or_port, + any_trusted_dir->descriptor_digest); + + } + } + + /* Mark a flag if we get a good skew from a trusted dir */ + if (labs(apparent_skew) < NETINFO_NOTICE_SKEW && + router_digest_is_trusted_dir(conn->identity_digest) && + !received_skew_from_trusted_dir) { + received_skew_from_trusted_dir = 1; }

/* XXX maybe act on my_apparent_addr, if the source is sufficiently