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Diffstat (limited to 'net/vmw_vsock')
-rw-r--r--net/vmw_vsock/af_vsock.c57
1 files changed, 46 insertions, 11 deletions
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 2e7a3034e965..1053662725f8 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -407,6 +407,8 @@ EXPORT_SYMBOL_GPL(vsock_enqueue_accept);
static bool vsock_use_local_transport(unsigned int remote_cid)
{
+ lockdep_assert_held(&vsock_register_mutex);
+
if (!transport_local)
return false;
@@ -464,6 +466,8 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk)
remote_flags = vsk->remote_addr.svm_flags;
+ mutex_lock(&vsock_register_mutex);
+
switch (sk->sk_type) {
case SOCK_DGRAM:
new_transport = transport_dgram;
@@ -479,12 +483,15 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk)
new_transport = transport_h2g;
break;
default:
- return -ESOCKTNOSUPPORT;
+ ret = -ESOCKTNOSUPPORT;
+ goto err;
}
if (vsk->transport) {
- if (vsk->transport == new_transport)
- return 0;
+ if (vsk->transport == new_transport) {
+ ret = 0;
+ goto err;
+ }
/* transport->release() must be called with sock lock acquired.
* This path can only be taken during vsock_connect(), where we
@@ -508,8 +515,16 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk)
/* We increase the module refcnt to prevent the transport unloading
* while there are open sockets assigned to it.
*/
- if (!new_transport || !try_module_get(new_transport->module))
- return -ENODEV;
+ if (!new_transport || !try_module_get(new_transport->module)) {
+ ret = -ENODEV;
+ goto err;
+ }
+
+ /* It's safe to release the mutex after a successful try_module_get().
+ * Whichever transport `new_transport` points at, it won't go away until
+ * the last module_put() below or in vsock_deassign_transport().
+ */
+ mutex_unlock(&vsock_register_mutex);
if (sk->sk_type == SOCK_SEQPACKET) {
if (!new_transport->seqpacket_allow ||
@@ -528,12 +543,31 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk)
vsk->transport = new_transport;
return 0;
+err:
+ mutex_unlock(&vsock_register_mutex);
+ return ret;
}
EXPORT_SYMBOL_GPL(vsock_assign_transport);
+/*
+ * Provide safe access to static transport_{h2g,g2h,dgram,local} callbacks.
+ * Otherwise we may race with module removal. Do not use on `vsk->transport`.
+ */
+static u32 vsock_registered_transport_cid(const struct vsock_transport **transport)
+{
+ u32 cid = VMADDR_CID_ANY;
+
+ mutex_lock(&vsock_register_mutex);
+ if (*transport)
+ cid = (*transport)->get_local_cid();
+ mutex_unlock(&vsock_register_mutex);
+
+ return cid;
+}
+
bool vsock_find_cid(unsigned int cid)
{
- if (transport_g2h && cid == transport_g2h->get_local_cid())
+ if (cid == vsock_registered_transport_cid(&transport_g2h))
return true;
if (transport_h2g && cid == VMADDR_CID_HOST)
@@ -2536,18 +2570,19 @@ static long vsock_dev_do_ioctl(struct file *filp,
unsigned int cmd, void __user *ptr)
{
u32 __user *p = ptr;
- u32 cid = VMADDR_CID_ANY;
int retval = 0;
+ u32 cid;
switch (cmd) {
case IOCTL_VM_SOCKETS_GET_LOCAL_CID:
/* To be compatible with the VMCI behavior, we prioritize the
* guest CID instead of well-know host CID (VMADDR_CID_HOST).
*/
- if (transport_g2h)
- cid = transport_g2h->get_local_cid();
- else if (transport_h2g)
- cid = transport_h2g->get_local_cid();
+ cid = vsock_registered_transport_cid(&transport_g2h);
+ if (cid == VMADDR_CID_ANY)
+ cid = vsock_registered_transport_cid(&transport_h2g);
+ if (cid == VMADDR_CID_ANY)
+ cid = vsock_registered_transport_cid(&transport_local);
if (put_user(cid, p) != 0)
retval = -EFAULT;