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vhost: fix possible denial of service by leaking FDs
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A malicious Vhost-user master could send in loop hand-crafted
vhost-user messages containing more file descriptors the
vhost-user slave expects. Doing so causes the application using
the vhost-user library to run out of FDs.

This issue has been assigned CVE-2019-14818

Fixes: 8f97231 ("vhost: support vhost-user")

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
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@mcoquelin @david-marchand
mcoquelin authored and david-marchand committed Nov 12, 2019
1 parent 612e17c commit bf47225
Showing 1 changed file with 115 additions and 4 deletions.
119 changes: 115 additions & 4 deletions lib/librte_vhost/vhost_user.c
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Original file line number Diff line number Diff line change
Expand Up @@ -92,6 +92,36 @@ static const char *vhost_message_str[VHOST_USER_MAX] = {
static int send_vhost_reply(int sockfd, struct VhostUserMsg *msg);
static int read_vhost_message(int sockfd, struct VhostUserMsg *msg);

static void
close_msg_fds(struct VhostUserMsg *msg)
{
int i;

for (i = 0; i < msg->fd_num; i++)
close(msg->fds[i]);
}

/*
* Ensure the expected number of FDs is received,
* close all FDs and return an error if this is not the case.
*/
static int
validate_msg_fds(struct VhostUserMsg *msg, int expected_fds)
{
if (msg->fd_num == expected_fds)
return 0;

RTE_LOG(ERR, VHOST_CONFIG,
" Expect %d FDs for request %s, received %d\n",
expected_fds,
vhost_message_str[msg->request.master],
msg->fd_num);

close_msg_fds(msg);

return -1;
}

static uint64_t
get_blk_size(int fd)
{
Expand Down Expand Up @@ -204,18 +234,25 @@ vhost_backend_cleanup(struct virtio_net *dev)
*/
static int
vhost_user_set_owner(struct virtio_net **pdev __rte_unused,
struct VhostUserMsg *msg __rte_unused,
struct VhostUserMsg *msg,
int main_fd __rte_unused)
{
if (validate_msg_fds(msg, 0) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

return RTE_VHOST_MSG_RESULT_OK;
}

static int
vhost_user_reset_owner(struct virtio_net **pdev,
struct VhostUserMsg *msg __rte_unused,
struct VhostUserMsg *msg,
int main_fd __rte_unused)
{
struct virtio_net *dev = *pdev;

if (validate_msg_fds(msg, 0) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

vhost_destroy_device_notify(dev);

cleanup_device(dev, 0);
Expand All @@ -233,6 +270,9 @@ vhost_user_get_features(struct virtio_net **pdev, struct VhostUserMsg *msg,
struct virtio_net *dev = *pdev;
uint64_t features = 0;

if (validate_msg_fds(msg, 0) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

rte_vhost_driver_get_features(dev->ifname, &features);

msg->payload.u64 = features;
Expand All @@ -252,6 +292,9 @@ vhost_user_get_queue_num(struct virtio_net **pdev, struct VhostUserMsg *msg,
struct virtio_net *dev = *pdev;
uint32_t queue_num = 0;

if (validate_msg_fds(msg, 0) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

rte_vhost_driver_get_queue_num(dev->ifname, &queue_num);

msg->payload.u64 = (uint64_t)queue_num;
Expand All @@ -274,6 +317,9 @@ vhost_user_set_features(struct virtio_net **pdev, struct VhostUserMsg *msg,
struct rte_vdpa_device *vdpa_dev;
int did = -1;

if (validate_msg_fds(msg, 0) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

rte_vhost_driver_get_features(dev->ifname, &vhost_features);
if (features & ~vhost_features) {
RTE_LOG(ERR, VHOST_CONFIG,
Expand Down Expand Up @@ -357,6 +403,9 @@ vhost_user_set_vring_num(struct virtio_net **pdev,
struct virtio_net *dev = *pdev;
struct vhost_virtqueue *vq = dev->virtqueue[msg->payload.state.index];

if (validate_msg_fds(msg, 0) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

vq->size = msg->payload.state.num;

/* VIRTIO 1.0, 2.4 Virtqueues says:
Expand Down Expand Up @@ -798,6 +847,9 @@ vhost_user_set_vring_addr(struct virtio_net **pdev, struct VhostUserMsg *msg,
struct vhost_vring_addr *addr = &msg->payload.addr;
bool access_ok;

if (validate_msg_fds(msg, 0) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

if (dev->mem == NULL)
return RTE_VHOST_MSG_RESULT_ERR;

Expand Down Expand Up @@ -839,6 +891,9 @@ vhost_user_set_vring_base(struct virtio_net **pdev,
struct vhost_virtqueue *vq = dev->virtqueue[msg->payload.state.index];
uint64_t val = msg->payload.state.num;

if (validate_msg_fds(msg, 0) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

if (vq_is_packed(dev)) {
/*
* Bit[0:14]: avail index
Expand Down Expand Up @@ -1000,6 +1055,9 @@ vhost_user_set_mem_table(struct virtio_net **pdev, struct VhostUserMsg *msg,
int populate;
int fd;

if (validate_msg_fds(msg, memory->nregions) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

if (memory->nregions > VHOST_MEMORY_MAX_NREGIONS) {
RTE_LOG(ERR, VHOST_CONFIG,
"too many memory regions (%u)\n", memory->nregions);
Expand All @@ -1010,8 +1068,7 @@ vhost_user_set_mem_table(struct virtio_net **pdev, struct VhostUserMsg *msg,
RTE_LOG(INFO, VHOST_CONFIG,
"(%d) memory regions not changed\n", dev->vid);

for (i = 0; i < memory->nregions; i++)
close(msg->fds[i]);
close_msg_fds(msg);

return RTE_VHOST_MSG_RESULT_OK;
}
Expand Down Expand Up @@ -1154,6 +1211,10 @@ vhost_user_set_mem_table(struct virtio_net **pdev, struct VhostUserMsg *msg,
"Failed to read qemu ack on postcopy set-mem-table\n");
goto err_mmap;
}

if (validate_msg_fds(&ack_msg, 0) != 0)
goto err_mmap;

if (ack_msg.request.master != VHOST_USER_SET_MEM_TABLE) {
RTE_LOG(ERR, VHOST_CONFIG,
"Bad qemu ack on postcopy set-mem-table (%d)\n",
Expand Down Expand Up @@ -1503,6 +1564,9 @@ vhost_user_set_vring_call(struct virtio_net **pdev, struct VhostUserMsg *msg,
struct vhost_vring_file file;
struct vhost_virtqueue *vq;

if (validate_msg_fds(msg, 1) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

file.index = msg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
if (msg->payload.u64 & VHOST_USER_VRING_NOFD_MASK)
file.fd = VIRTIO_INVALID_EVENTFD;
Expand All @@ -1524,6 +1588,9 @@ static int vhost_user_set_vring_err(struct virtio_net **pdev __rte_unused,
struct VhostUserMsg *msg,
int main_fd __rte_unused)
{
if (validate_msg_fds(msg, 1) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

if (!(msg->payload.u64 & VHOST_USER_VRING_NOFD_MASK))
close(msg->fds[0]);
RTE_LOG(INFO, VHOST_CONFIG, "not implemented\n");
Expand Down Expand Up @@ -1724,6 +1791,9 @@ vhost_user_set_vring_kick(struct virtio_net **pdev, struct VhostUserMsg *msg,
struct vhost_vring_file file;
struct vhost_virtqueue *vq;

if (validate_msg_fds(msg, 1) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

file.index = msg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
if (msg->payload.u64 & VHOST_USER_VRING_NOFD_MASK)
file.fd = VIRTIO_INVALID_EVENTFD;
Expand Down Expand Up @@ -1794,6 +1864,9 @@ vhost_user_get_vring_base(struct virtio_net **pdev,
struct vhost_virtqueue *vq = dev->virtqueue[msg->payload.state.index];
uint64_t val;

if (validate_msg_fds(msg, 0) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

/* We have to stop the queue (virtio) if it is running. */
vhost_destroy_device_notify(dev);

Expand Down Expand Up @@ -1869,6 +1942,9 @@ vhost_user_set_vring_enable(struct virtio_net **pdev,
struct rte_vdpa_device *vdpa_dev;
int did = -1;

if (validate_msg_fds(msg, 0) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

RTE_LOG(INFO, VHOST_CONFIG,
"set queue enable: %d to qp idx: %d\n",
enable, index);
Expand Down Expand Up @@ -1899,6 +1975,9 @@ vhost_user_get_protocol_features(struct virtio_net **pdev,
struct virtio_net *dev = *pdev;
uint64_t features, protocol_features;

if (validate_msg_fds(msg, 0) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

rte_vhost_driver_get_features(dev->ifname, &features);
rte_vhost_driver_get_protocol_features(dev->ifname, &protocol_features);

Expand Down Expand Up @@ -1927,6 +2006,9 @@ vhost_user_set_protocol_features(struct virtio_net **pdev,
uint64_t protocol_features = msg->payload.u64;
uint64_t slave_protocol_features = 0;

if (validate_msg_fds(msg, 0) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

rte_vhost_driver_get_protocol_features(dev->ifname,
&slave_protocol_features);
if (protocol_features & ~slave_protocol_features) {
Expand All @@ -1953,6 +2035,9 @@ vhost_user_set_log_base(struct virtio_net **pdev, struct VhostUserMsg *msg,
uint64_t size, off;
void *addr;

if (validate_msg_fds(msg, 1) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

if (fd < 0) {
RTE_LOG(ERR, VHOST_CONFIG, "invalid log fd: %d\n", fd);
return RTE_VHOST_MSG_RESULT_ERR;
Expand Down Expand Up @@ -2016,6 +2101,9 @@ static int vhost_user_set_log_fd(struct virtio_net **pdev __rte_unused,
struct VhostUserMsg *msg,
int main_fd __rte_unused)
{
if (validate_msg_fds(msg, 1) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

close(msg->fds[0]);
RTE_LOG(INFO, VHOST_CONFIG, "not implemented.\n");

Expand All @@ -2039,6 +2127,9 @@ vhost_user_send_rarp(struct virtio_net **pdev, struct VhostUserMsg *msg,
struct rte_vdpa_device *vdpa_dev;
int did = -1;

if (validate_msg_fds(msg, 0) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

RTE_LOG(DEBUG, VHOST_CONFIG,
":: mac: %02x:%02x:%02x:%02x:%02x:%02x\n",
mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
Expand Down Expand Up @@ -2066,6 +2157,10 @@ vhost_user_net_set_mtu(struct virtio_net **pdev, struct VhostUserMsg *msg,
int main_fd __rte_unused)
{
struct virtio_net *dev = *pdev;

if (validate_msg_fds(msg, 0) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

if (msg->payload.u64 < VIRTIO_MIN_MTU ||
msg->payload.u64 > VIRTIO_MAX_MTU) {
RTE_LOG(ERR, VHOST_CONFIG, "Invalid MTU size (%"PRIu64")\n",
Expand All @@ -2086,6 +2181,9 @@ vhost_user_set_req_fd(struct virtio_net **pdev, struct VhostUserMsg *msg,
struct virtio_net *dev = *pdev;
int fd = msg->fds[0];

if (validate_msg_fds(msg, 1) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

if (fd < 0) {
RTE_LOG(ERR, VHOST_CONFIG,
"Invalid file descriptor for slave channel (%d)\n",
Expand Down Expand Up @@ -2171,6 +2269,9 @@ vhost_user_iotlb_msg(struct virtio_net **pdev, struct VhostUserMsg *msg,
uint16_t i;
uint64_t vva, len;

if (validate_msg_fds(msg, 0) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

switch (imsg->type) {
case VHOST_IOTLB_UPDATE:
len = imsg->size;
Expand Down Expand Up @@ -2217,6 +2318,9 @@ vhost_user_set_postcopy_advise(struct virtio_net **pdev,
#ifdef RTE_LIBRTE_VHOST_POSTCOPY
struct uffdio_api api_struct;

if (validate_msg_fds(msg, 0) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

dev->postcopy_ufd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);

if (dev->postcopy_ufd == -1) {
Expand Down Expand Up @@ -2252,6 +2356,9 @@ vhost_user_set_postcopy_listen(struct virtio_net **pdev,
{
struct virtio_net *dev = *pdev;

if (validate_msg_fds(msg, 0) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

if (dev->mem && dev->mem->nregions) {
RTE_LOG(ERR, VHOST_CONFIG,
"Regions already registered at postcopy-listen\n");
Expand All @@ -2268,6 +2375,9 @@ vhost_user_postcopy_end(struct virtio_net **pdev, struct VhostUserMsg *msg,
{
struct virtio_net *dev = *pdev;

if (validate_msg_fds(msg, 0) != 0)
return RTE_VHOST_MSG_RESULT_ERR;

dev->postcopy_listening = 0;
if (dev->postcopy_ufd >= 0) {
close(dev->postcopy_ufd);
Expand Down Expand Up @@ -2621,6 +2731,7 @@ vhost_user_msg_handler(int vid, int fd)
if (!handled) {
RTE_LOG(ERR, VHOST_CONFIG,
"vhost message (req: %d) was not handled.\n", request);
close_msg_fds(&msg);
ret = RTE_VHOST_MSG_RESULT_ERR;
}

Expand Down

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