commit f367453cb5a9ea5cb0d5664425256d7abbcbb407
parent 711160a46f5fbba7106c23c29f99bed75928a5a7
Author: Nick Mathewson <nickm@torproject.org>
Date: Tue, 27 Jun 2017 12:01:46 -0400
Mark descriptors as undownloadable when dirserv_add_() rejects them
As of ac2f6b608a18a8595f62384788196d7c3f2875fd in 0.2.1.19-alpha,
Sebastian fixed bug 888 by marking descriptors as "impossible" by
digest if they got rejected during the
router_load_routers_from_string() phase. This fix stopped clients
and relays from downloading the same thing over and over.
But we never made the same change for descriptors rejected during
dirserv_add_{descriptor,extrainfo}. Instead, we tried to notice in
advance that we'd reject them with dirserv_would_reject().
This notice-in-advance check stopped working once we added
key-pinning and didn't make a corresponding key-pinning change to
dirserv_would_reject() [since a routerstatus_t doesn't include an
ed25519 key].
So as a fix, let's make the dirserv_add_*() functions mark digests
as undownloadable when they are rejected.
Fixes bug 22349; I am calling this a fix on 0.2.1.19-alpha, though
you could also argue for it being a fix on 0.2.7.2-alpha.
Diffstat:
2 files changed, 53 insertions(+), 12 deletions(-)
diff --git a/changes/bug22349 b/changes/bug22349
@@ -0,0 +1,9 @@
+ o Minor bugfixes (directory authority):
+ - When a directory authority rejects a descriptor or extrainfo with
+ a given digest, mark that digest as undownloadable, so that we
+ do not attempt to download it again over and over. We previously
+ tried to avoid downloading such descriptors by other means, but
+ we didn't notice if we accidentally downloaded one anyway. This
+ behavior became problematic in 0.2.7.2-alpha, when authorities
+ began pinning Ed25519 keys. Fixes ticket
+ 22349; bugfix on 0.2.1.19-alpha.
diff --git a/src/or/dirserv.c b/src/or/dirserv.c
@@ -658,8 +658,8 @@ dirserv_add_descriptor(routerinfo_t *ri, const char **msg, const char *source)
control_event_or_authdir_new_descriptor("REJECTED",
ri->cache_info.signed_descriptor_body,
desclen, *msg);
- routerinfo_free(ri);
- return ROUTER_AUTHDIR_REJECTS;
+ r = ROUTER_AUTHDIR_REJECTS;
+ goto fail;
}
/* Check whether this descriptor is semantically identical to the last one
@@ -679,8 +679,8 @@ dirserv_add_descriptor(routerinfo_t *ri, const char **msg, const char *source)
control_event_or_authdir_new_descriptor("DROPPED",
ri->cache_info.signed_descriptor_body,
desclen, *msg);
- routerinfo_free(ri);
- return ROUTER_IS_ALREADY_KNOWN;
+ r = ROUTER_IS_ALREADY_KNOWN;
+ goto fail;
}
/* Do keypinning again ... this time, to add the pin if appropriate */
@@ -703,8 +703,8 @@ dirserv_add_descriptor(routerinfo_t *ri, const char **msg, const char *source)
"its key did not match an older RSA/Ed25519 keypair",
router_describe(ri), source);
*msg = "Looks like your keypair does not match its older value.";
- routerinfo_free(ri);
- return ROUTER_AUTHDIR_REJECTS;
+ r = ROUTER_AUTHDIR_REJECTS;
+ goto fail;
}
/* Make a copy of desc, since router_add_to_routerlist might free
@@ -742,6 +742,20 @@ dirserv_add_descriptor(routerinfo_t *ri, const char **msg, const char *source)
tor_free(desc);
tor_free(nickname);
return r;
+ fail:
+ {
+ const char *desc_digest = ri->cache_info.signed_descriptor_digest;
+ download_status_t *dls =
+ router_get_dl_status_by_descriptor_digest(desc_digest);
+ if (dls) {
+ log_info(LD_GENERAL, "Marking router with descriptor %s as rejected, "
+ "and therefore undownloadable",
+ hex_str(desc_digest, DIGEST_LEN));
+ download_status_mark_impossible(dls);
+ }
+ routerinfo_free(ri);
+ }
+ return r;
}
/** As dirserv_add_descriptor, but for an extrainfo_t <b>ei</b>. */
@@ -750,6 +764,7 @@ dirserv_add_extrainfo(extrainfo_t *ei, const char **msg)
{
routerinfo_t *ri;
int r;
+ was_router_added_t rv;
tor_assert(msg);
*msg = NULL;
@@ -758,8 +773,8 @@ dirserv_add_extrainfo(extrainfo_t *ei, const char **msg)
ri = router_get_mutable_by_digest(ei->cache_info.identity_digest);
if (!ri) {
*msg = "No corresponding router descriptor for extra-info descriptor";
- extrainfo_free(ei);
- return ROUTER_BAD_EI;
+ rv = ROUTER_BAD_EI;
+ goto fail;
}
/* If it's too big, refuse it now. Otherwise we'll cache it all over the
@@ -771,17 +786,34 @@ dirserv_add_extrainfo(extrainfo_t *ei, const char **msg)
(int)ei->cache_info.signed_descriptor_len,
MAX_EXTRAINFO_UPLOAD_SIZE);
*msg = "Extrainfo document was too large";
- extrainfo_free(ei);
- return ROUTER_BAD_EI;
+ rv = ROUTER_BAD_EI;
+ goto fail;
}
if ((r = routerinfo_incompatible_with_extrainfo(ri->identity_pkey, ei,
&ri->cache_info, msg))) {
- extrainfo_free(ei);
- return r < 0 ? ROUTER_IS_ALREADY_KNOWN : ROUTER_BAD_EI;
+ if (r<0) {
+ extrainfo_free(ei);
+ return ROUTER_IS_ALREADY_KNOWN;
+ }
+ rv = ROUTER_BAD_EI;
+ goto fail;
}
router_add_extrainfo_to_routerlist(ei, msg, 0, 0);
return ROUTER_ADDED_SUCCESSFULLY;
+ fail:
+ {
+ const char *d = ei->cache_info.signed_descriptor_digest;
+ signed_descriptor_t *sd = router_get_by_extrainfo_digest((char*)d);
+ if (sd) {
+ log_info(LD_GENERAL, "Marking extrainfo with descriptor %s as "
+ "rejected, and therefore undownloadable",
+ hex_str((char*)d,DIGEST_LEN));
+ download_status_mark_impossible(&sd->ei_dl_status);
+ }
+ extrainfo_free(ei);
+ }
+ return rv;
}
/** Remove all descriptors whose nicknames or fingerprints no longer
