From ee23b82cc9174c96ea73252e2986cf822999494b Mon Sep 17 00:00:00 2001

From: Jon Maloy <jmaloy@redhat.com>

Date: Tue, 29 Jun 2021 03:42:39 -0400

Subject: [PATCH 1/9] net: introduce qemu_receive_packet()

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RH-Author: Jon Maloy <jmaloy@redhat.com>

Message-id: <20210629034247.3286477-2-jmaloy@redhat.com>

Patchwork-id: 101785

O-Subject: [RHEL-8.4.0.z qemu-kvm PATCH v2 1/9] net: introduce qemu_receive_packet()

Bugzilla: 1932917

RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Thomas Huth <thuth@redhat.com>

From: Jason Wang <jasowang@redhat.com>

Some NIC supports loopback mode and this is done by calling

nc->info->receive() directly which in fact suppresses the effort of

reentrancy check that is done in qemu_net_queue_send().

Unfortunately we can't use qemu_net_queue_send() here since for

loopback there's no sender as peer, so this patch introduce a

qemu_receive_packet() which is used for implementing loopback mode

for a NIC with this check.

NIC that supports loopback mode will be converted to this helper.

This is intended to address CVE-2021-3416.

Cc: Prasad J Pandit <ppandit@redhat.com>

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

Cc: qemu-stable@nongnu.org

Signed-off-by: Jason Wang <jasowang@redhat.com>

(cherry picked from commit 705df5466c98f3efdd2b68d3b31dad86858acad7)

Signed-off-by: Jon Maloy <jmaloy@redhat.com>

Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>

---

 include/net/net.h   |  5 +++++

 include/net/queue.h |  8 ++++++++

 net/net.c           | 38 +++++++++++++++++++++++++++++++-------

 net/queue.c         | 22 ++++++++++++++++++++++

 4 files changed, 66 insertions(+), 7 deletions(-)

diff --git a/include/net/net.h b/include/net/net.h

index e175ba9677..1b32a8aaec 100644

--- a/include/net/net.h

+++ b/include/net/net.h

@@ -142,12 +142,17 @@ void *qemu_get_nic_opaque(NetClientState *nc);

 void qemu_del_net_client(NetClientState *nc);

 typedef void (*qemu_nic_foreach)(NICState *nic, void *opaque);

 void qemu_foreach_nic(qemu_nic_foreach func, void *opaque);

+int qemu_can_receive_packet(NetClientState *nc);

 int qemu_can_send_packet(NetClientState *nc);

 ssize_t qemu_sendv_packet(NetClientState *nc, const struct iovec *iov,

                           int iovcnt);

 ssize_t qemu_sendv_packet_async(NetClientState *nc, const struct iovec *iov,

                                 int iovcnt, NetPacketSent *sent_cb);

 ssize_t qemu_send_packet(NetClientState *nc, const uint8_t *buf, int size);

+ssize_t qemu_receive_packet(NetClientState *nc, const uint8_t *buf, int size);

+ssize_t qemu_receive_packet_iov(NetClientState *nc,

+                                const struct iovec *iov,

+                                int iovcnt);

 ssize_t qemu_send_packet_raw(NetClientState *nc, const uint8_t *buf, int size);

 ssize_t qemu_send_packet_async(NetClientState *nc, const uint8_t *buf,

                                int size, NetPacketSent *sent_cb);

diff --git a/include/net/queue.h b/include/net/queue.h

index c0269bb1dc..9f2f289d77 100644

--- a/include/net/queue.h

+++ b/include/net/queue.h

@@ -55,6 +55,14 @@ void qemu_net_queue_append_iov(NetQueue *queue,

 void qemu_del_net_queue(NetQueue *queue);

+ssize_t qemu_net_queue_receive(NetQueue *queue,

+                               const uint8_t *data,

+                               size_t size);

+

+ssize_t qemu_net_queue_receive_iov(NetQueue *queue,

+                                   const struct iovec *iov,

+                                   int iovcnt);

+

 ssize_t qemu_net_queue_send(NetQueue *queue,

                             NetClientState *sender,

                             unsigned flags,

diff --git a/net/net.c b/net/net.c

index 84aa6d8d00..d0b651ca95 100644

--- a/net/net.c

+++ b/net/net.c

@@ -516,6 +516,17 @@ int qemu_set_vnet_be(NetClientState *nc, bool is_be)

 #endif

 }

+int qemu_can_receive_packet(NetClientState *nc)

+{

+    if (nc->receive_disabled) {

+        return 0;

+    } else if (nc->info->can_receive &&

+               !nc->info->can_receive(nc)) {

+        return 0;

+    }

+    return 1;

+}

+

 int qemu_can_send_packet(NetClientState *sender)

 {

     int vm_running = runstate_is_running();

@@ -528,13 +539,7 @@ int qemu_can_send_packet(NetClientState *sender)

         return 1;

     }

-    if (sender->peer->receive_disabled) {

-        return 0;

-    } else if (sender->peer->info->can_receive &&

-               !sender->peer->info->can_receive(sender->peer)) {

-        return 0;

-    }

-    return 1;

+    return qemu_can_receive_packet(sender->peer);

 }

 static ssize_t filter_receive_iov(NetClientState *nc,

@@ -667,6 +672,25 @@ ssize_t qemu_send_packet(NetClientState *nc, const uint8_t *buf, int size)

     return qemu_send_packet_async(nc, buf, size, NULL);

 }

+ssize_t qemu_receive_packet(NetClientState *nc, const uint8_t *buf, int size)

+{

+    if (!qemu_can_receive_packet(nc)) {

+        return 0;

+    }

+

+    return qemu_net_queue_receive(nc->incoming_queue, buf, size);

+}

+

+ssize_t qemu_receive_packet_iov(NetClientState *nc, const struct iovec *iov,

+                                int iovcnt)

+{

+    if (!qemu_can_receive_packet(nc)) {

+        return 0;

+    }

+

+    return qemu_net_queue_receive_iov(nc->incoming_queue, iov, iovcnt);

+}

+

 ssize_t qemu_send_packet_raw(NetClientState *nc, const uint8_t *buf, int size)

 {

     return qemu_send_packet_async_with_flags(nc, QEMU_NET_PACKET_FLAG_RAW,

diff --git a/net/queue.c b/net/queue.c

index 61276ca4be..7c0b72c8ef 100644

--- a/net/queue.c

+++ b/net/queue.c

@@ -182,6 +182,28 @@ static ssize_t qemu_net_queue_deliver_iov(NetQueue *queue,

     return ret;

 }

+ssize_t qemu_net_queue_receive(NetQueue *queue,

+                               const uint8_t *data,

+                               size_t size)

+{

+    if (queue->delivering) {

+        return 0;

+    }

+

+    return qemu_net_queue_deliver(queue, NULL, 0, data, size);

+}

+

+ssize_t qemu_net_queue_receive_iov(NetQueue *queue,

+                                   const struct iovec *iov,

+                                   int iovcnt)

+{

+    if (queue->delivering) {

+        return 0;

+    }

+

+    return qemu_net_queue_deliver_iov(queue, NULL, 0, iov, iovcnt);

+}

+

 ssize_t qemu_net_queue_send(NetQueue *queue,

                             NetClientState *sender,

                             unsigned flags,

-- 

2.27.0