diff options
Diffstat (limited to 'app-emulation/qemu/files/qemu-2.9.0-CVE-2017-9524-2.patch')
| -rw-r--r-- | app-emulation/qemu/files/qemu-2.9.0-CVE-2017-9524-2.patch | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/app-emulation/qemu/files/qemu-2.9.0-CVE-2017-9524-2.patch b/app-emulation/qemu/files/qemu-2.9.0-CVE-2017-9524-2.patch new file mode 100644 index 000000000000..e6934b379a26 --- /dev/null +++ b/app-emulation/qemu/files/qemu-2.9.0-CVE-2017-9524-2.patch @@ -0,0 +1,197 @@ +From 0c9390d978cbf61e8f16c9f580fa96b305c43568 Mon Sep 17 00:00:00 2001 +From: Eric Blake <eblake@redhat.com> +Date: Thu, 8 Jun 2017 17:26:17 -0500 +Subject: [PATCH] nbd: Fix regression on resiliency to port scan + +Back in qemu 2.5, qemu-nbd was immune to port probes (a transient +server would not quit, regardless of how many probe connections +came and went, until a connection actually negotiated). But we +broke that in commit ee7d7aa when removing the return value to +nbd_client_new(), although that patch also introduced a bug causing +an assertion failure on a client that fails negotiation. We then +made it worse during refactoring in commit 1a6245a (a segfault +before we could even assert); the (masked) assertion was cleaned +up in d3780c2 (still in 2.6), and just recently we finally fixed +the segfault ("nbd: Fully intialize client in case of failed +negotiation"). But that still means that ever since we added +TLS support to qemu-nbd, we have been vulnerable to an ill-timed +port-scan being able to cause a denial of service by taking down +qemu-nbd before a real client has a chance to connect. + +Since negotiation is now handled asynchronously via coroutines, +we no longer have a synchronous point of return by re-adding a +return value to nbd_client_new(). So this patch instead wires +things up to pass the negotiation status through the close_fn +callback function. + +Simple test across two terminals: +$ qemu-nbd -f raw -p 30001 file +$ nmap 127.0.0.1 -p 30001 && \ + qemu-io -c 'r 0 512' -f raw nbd://localhost:30001 + +Note that this patch does not change what constitutes successful +negotiation (thus, a client must enter transmission phase before +that client can be considered as a reason to terminate the server +when the connection ends). Perhaps we may want to tweak things +in a later patch to also treat a client that uses NBD_OPT_ABORT +as being a 'successful' negotiation (the client correctly talked +the NBD protocol, and informed us it was not going to use our +export after all), but that's a discussion for another day. + +Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1451614 + +Signed-off-by: Eric Blake <eblake@redhat.com> +Message-Id: <20170608222617.20376-1-eblake@redhat.com> +Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> +--- + blockdev-nbd.c | 6 +++++- + include/block/nbd.h | 2 +- + nbd/server.c | 24 +++++++++++++++--------- + qemu-nbd.c | 4 ++-- + 4 files changed, 23 insertions(+), 13 deletions(-) + +diff --git a/blockdev-nbd.c b/blockdev-nbd.c +index dd0860f4a6..28f551a7b0 100644 +--- a/blockdev-nbd.c ++++ b/blockdev-nbd.c +@@ -27,6 +27,10 @@ typedef struct NBDServerData { + + static NBDServerData *nbd_server; + ++static void nbd_blockdev_client_closed(NBDClient *client, bool ignored) ++{ ++ nbd_client_put(client); ++} + + static gboolean nbd_accept(QIOChannel *ioc, GIOCondition condition, + gpointer opaque) +@@ -46,7 +50,7 @@ static gboolean nbd_accept(QIOChannel *ioc, GIOCondition condition, + qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server"); + nbd_client_new(NULL, cioc, + nbd_server->tlscreds, NULL, +- nbd_client_put); ++ nbd_blockdev_client_closed); + object_unref(OBJECT(cioc)); + return TRUE; + } +diff --git a/include/block/nbd.h b/include/block/nbd.h +index 416257abca..8fa5ce51f3 100644 +--- a/include/block/nbd.h ++++ b/include/block/nbd.h +@@ -162,7 +162,7 @@ void nbd_client_new(NBDExport *exp, + QIOChannelSocket *sioc, + QCryptoTLSCreds *tlscreds, + const char *tlsaclname, +- void (*close)(NBDClient *)); ++ void (*close_fn)(NBDClient *, bool)); + void nbd_client_get(NBDClient *client); + void nbd_client_put(NBDClient *client); + +diff --git a/nbd/server.c b/nbd/server.c +index 49b55f6ede..f2b1aa47ce 100644 +--- a/nbd/server.c ++++ b/nbd/server.c +@@ -81,7 +81,7 @@ static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports); + + struct NBDClient { + int refcount; +- void (*close)(NBDClient *client); ++ void (*close_fn)(NBDClient *client, bool negotiated); + + bool no_zeroes; + NBDExport *exp; +@@ -778,7 +778,7 @@ void nbd_client_put(NBDClient *client) + } + } + +-static void client_close(NBDClient *client) ++static void client_close(NBDClient *client, bool negotiated) + { + if (client->closing) { + return; +@@ -793,8 +793,8 @@ static void client_close(NBDClient *client) + NULL); + + /* Also tell the client, so that they release their reference. */ +- if (client->close) { +- client->close(client); ++ if (client->close_fn) { ++ client->close_fn(client, negotiated); + } + } + +@@ -975,7 +975,7 @@ void nbd_export_close(NBDExport *exp) + + nbd_export_get(exp); + QTAILQ_FOREACH_SAFE(client, &exp->clients, next, next) { +- client_close(client); ++ client_close(client, true); + } + nbd_export_set_name(exp, NULL); + nbd_export_set_description(exp, NULL); +@@ -1337,7 +1337,7 @@ done: + + out: + nbd_request_put(req); +- client_close(client); ++ client_close(client, true); + nbd_client_put(client); + } + +@@ -1363,7 +1363,7 @@ static coroutine_fn void nbd_co_client_start(void *opaque) + qemu_co_mutex_init(&client->send_lock); + + if (nbd_negotiate(data)) { +- client_close(client); ++ client_close(client, false); + goto out; + } + +@@ -1373,11 +1373,17 @@ out: + g_free(data); + } + ++/* ++ * Create a new client listener on the given export @exp, using the ++ * given channel @sioc. Begin servicing it in a coroutine. When the ++ * connection closes, call @close_fn with an indication of whether the ++ * client completed negotiation. ++ */ + void nbd_client_new(NBDExport *exp, + QIOChannelSocket *sioc, + QCryptoTLSCreds *tlscreds, + const char *tlsaclname, +- void (*close_fn)(NBDClient *)) ++ void (*close_fn)(NBDClient *, bool)) + { + NBDClient *client; + NBDClientNewData *data = g_new(NBDClientNewData, 1); +@@ -1394,7 +1400,7 @@ void nbd_client_new(NBDExport *exp, + object_ref(OBJECT(client->sioc)); + client->ioc = QIO_CHANNEL(sioc); + object_ref(OBJECT(client->ioc)); +- client->close = close_fn; ++ client->close_fn = close_fn; + + data->client = client; + data->co = qemu_coroutine_create(nbd_co_client_start, data); +diff --git a/qemu-nbd.c b/qemu-nbd.c +index 651f85ecc1..9464a0461c 100644 +--- a/qemu-nbd.c ++++ b/qemu-nbd.c +@@ -336,10 +336,10 @@ static void nbd_export_closed(NBDExport *exp) + + static void nbd_update_server_watch(void); + +-static void nbd_client_closed(NBDClient *client) ++static void nbd_client_closed(NBDClient *client, bool negotiated) + { + nb_fds--; +- if (nb_fds == 0 && !persistent && state == RUNNING) { ++ if (negotiated && nb_fds == 0 && !persistent && state == RUNNING) { + state = TERMINATE; + } + nbd_update_server_watch(); +-- +2.13.0 + |