openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 126 insertions, 0 deletions

diff --git a/drivers/virt/acrn/vm.c b/drivers/virt/acrn/vm.c
new file mode 100644
index 000000000..3753b27c5
--- /dev/null
+++ b/drivers/virt/acrn/vm.c
@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ACRN_HSM: Virtual Machine management
+ *
+ * Copyright (C) 2020 Intel Corporation. All rights reserved.
+ *
+ * Authors:
+ *	Jason Chen CJ <jason.cj.chen@intel.com>
+ *	Yakui Zhao <yakui.zhao@intel.com>
+ */
+#include <linux/io.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+
+#include "acrn_drv.h"
+
+/* List of VMs */
+LIST_HEAD(acrn_vm_list);
+/*
+ * acrn_vm_list is read in a worker thread which dispatch I/O requests and
+ * is wrote in VM creation ioctl. Use the rwlock mechanism to protect it.
+ */
+DEFINE_RWLOCK(acrn_vm_list_lock);
+
+struct acrn_vm *acrn_vm_create(struct acrn_vm *vm,
+			       struct acrn_vm_creation *vm_param)
+{
+	int ret;
+
+	ret = hcall_create_vm(virt_to_phys(vm_param));
+	if (ret < 0 || vm_param->vmid == ACRN_INVALID_VMID) {
+		dev_err(acrn_dev.this_device,
+			"Failed to create VM! Error: %d\n", ret);
+		return NULL;
+	}
+
+	mutex_init(&vm->regions_mapping_lock);
+	INIT_LIST_HEAD(&vm->ioreq_clients);
+	spin_lock_init(&vm->ioreq_clients_lock);
+	vm->vmid = vm_param->vmid;
+	vm->vcpu_num = vm_param->vcpu_num;
+
+	if (acrn_ioreq_init(vm, vm_param->ioreq_buf) < 0) {
+		hcall_destroy_vm(vm_param->vmid);
+		vm->vmid = ACRN_INVALID_VMID;
+		return NULL;
+	}
+
+	write_lock_bh(&acrn_vm_list_lock);
+	list_add(&vm->list, &acrn_vm_list);
+	write_unlock_bh(&acrn_vm_list_lock);
+
+	acrn_ioeventfd_init(vm);
+	acrn_irqfd_init(vm);
+	dev_dbg(acrn_dev.this_device, "VM %u created.\n", vm->vmid);
+	return vm;
+}
+
+int acrn_vm_destroy(struct acrn_vm *vm)
+{
+	int ret;
+
+	if (vm->vmid == ACRN_INVALID_VMID ||
+	    test_and_set_bit(ACRN_VM_FLAG_DESTROYED, &vm->flags))
+		return 0;
+
+	ret = hcall_destroy_vm(vm->vmid);
+	if (ret < 0) {
+		dev_err(acrn_dev.this_device,
+			"Failed to destroy VM %u\n", vm->vmid);
+		clear_bit(ACRN_VM_FLAG_DESTROYED, &vm->flags);
+		return ret;
+	}
+
+	/* Remove from global VM list */
+	write_lock_bh(&acrn_vm_list_lock);
+	list_del_init(&vm->list);
+	write_unlock_bh(&acrn_vm_list_lock);
+
+	acrn_ioeventfd_deinit(vm);
+	acrn_irqfd_deinit(vm);
+	acrn_ioreq_deinit(vm);
+
+	if (vm->monitor_page) {
+		put_page(vm->monitor_page);
+		vm->monitor_page = NULL;
+	}
+
+	acrn_vm_all_ram_unmap(vm);
+
+	dev_dbg(acrn_dev.this_device, "VM %u destroyed.\n", vm->vmid);
+	vm->vmid = ACRN_INVALID_VMID;
+	return 0;
+}
+
+/**
+ * acrn_msi_inject() - Inject a MSI interrupt into a User VM
+ * @vm:		User VM
+ * @msi_addr:	The MSI address
+ * @msi_data:	The MSI data
+ *
+ * Return: 0 on success, <0 on error
+ */
+int acrn_msi_inject(struct acrn_vm *vm, u64 msi_addr, u64 msi_data)
+{
+	struct acrn_msi_entry *msi;
+	int ret;
+
+	/* might be used in interrupt context, so use GFP_ATOMIC */
+	msi = kzalloc_obj(*msi, GFP_ATOMIC);
+	if (!msi)
+		return -ENOMEM;
+
+	/*
+	 * msi_addr: addr[19:12] with dest vcpu id
+	 * msi_data: data[7:0] with vector
+	 */
+	msi->msi_addr = msi_addr;
+	msi->msi_data = msi_data;
+	ret = hcall_inject_msi(vm->vmid, virt_to_phys(msi));
+	if (ret < 0)
+		dev_err(acrn_dev.this_device,
+			"Failed to inject MSI to VM %u!\n", vm->vmid);
+	kfree(msi);
+	return ret;
+}