| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Copyright IBM Corp. 2022 |
| * Author(s): Steffen Eiden <seiden@linux.ibm.com> |
| * |
| * This file provides a Linux misc device to give userspace access to some |
| * Ultravisor (UV) functions. The device only accepts IOCTLs and will only |
| * be present if the Ultravisor facility (158) is present. |
| * |
| * When userspace sends a valid IOCTL uvdevice will copy the input data to |
| * kernel space, do some basic validity checks to avoid kernel/system |
| * corruption. Any other check that the Ultravisor does will not be done by |
| * the uvdevice to keep changes minimal when adding new functionalities |
| * to existing UV-calls. |
| * After the checks uvdevice builds a corresponding |
| * Ultravisor Call Control Block, and sends the request to the Ultravisor. |
| * Then, it copies the response, including the return codes, back to userspace. |
| * It is the responsibility of the userspace to check for any error issued |
| * by UV and to interpret the UV response. The uvdevice acts as a communication |
| * channel for userspace to the Ultravisor. |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/kernel.h> |
| #include <linux/miscdevice.h> |
| #include <linux/types.h> |
| #include <linux/stddef.h> |
| #include <linux/vmalloc.h> |
| #include <linux/slab.h> |
| |
| #include <asm/uvdevice.h> |
| #include <asm/uv.h> |
| |
| static int uvio_build_uvcb_attest(struct uv_cb_attest *uvcb_attest, u8 *arcb, |
| u8 *meas, u8 *add_data, struct uvio_attest *uvio_attest) |
| { |
| void __user *user_buf_arcb = (void __user *)uvio_attest->arcb_addr; |
| |
| if (copy_from_user(arcb, user_buf_arcb, uvio_attest->arcb_len)) |
| return -EFAULT; |
| |
| uvcb_attest->header.len = sizeof(*uvcb_attest); |
| uvcb_attest->header.cmd = UVC_CMD_RETR_ATTEST; |
| uvcb_attest->arcb_addr = (u64)arcb; |
| uvcb_attest->cont_token = 0; |
| uvcb_attest->user_data_len = uvio_attest->user_data_len; |
| memcpy(uvcb_attest->user_data, uvio_attest->user_data, sizeof(uvcb_attest->user_data)); |
| uvcb_attest->meas_len = uvio_attest->meas_len; |
| uvcb_attest->meas_addr = (u64)meas; |
| uvcb_attest->add_data_len = uvio_attest->add_data_len; |
| uvcb_attest->add_data_addr = (u64)add_data; |
| |
| return 0; |
| } |
| |
| static int uvio_copy_attest_result_to_user(struct uv_cb_attest *uvcb_attest, |
| struct uvio_ioctl_cb *uv_ioctl, |
| u8 *measurement, u8 *add_data, |
| struct uvio_attest *uvio_attest) |
| { |
| struct uvio_attest __user *user_uvio_attest = (void __user *)uv_ioctl->argument_addr; |
| void __user *user_buf_add = (void __user *)uvio_attest->add_data_addr; |
| void __user *user_buf_meas = (void __user *)uvio_attest->meas_addr; |
| void __user *user_buf_uid = &user_uvio_attest->config_uid; |
| |
| if (copy_to_user(user_buf_meas, measurement, uvio_attest->meas_len)) |
| return -EFAULT; |
| if (add_data && copy_to_user(user_buf_add, add_data, uvio_attest->add_data_len)) |
| return -EFAULT; |
| if (copy_to_user(user_buf_uid, uvcb_attest->config_uid, sizeof(uvcb_attest->config_uid))) |
| return -EFAULT; |
| return 0; |
| } |
| |
| static int get_uvio_attest(struct uvio_ioctl_cb *uv_ioctl, struct uvio_attest *uvio_attest) |
| { |
| u8 __user *user_arg_buf = (u8 __user *)uv_ioctl->argument_addr; |
| |
| if (copy_from_user(uvio_attest, user_arg_buf, sizeof(*uvio_attest))) |
| return -EFAULT; |
| |
| if (uvio_attest->arcb_len > UVIO_ATT_ARCB_MAX_LEN) |
| return -EINVAL; |
| if (uvio_attest->arcb_len == 0) |
| return -EINVAL; |
| if (uvio_attest->meas_len > UVIO_ATT_MEASUREMENT_MAX_LEN) |
| return -EINVAL; |
| if (uvio_attest->meas_len == 0) |
| return -EINVAL; |
| if (uvio_attest->add_data_len > UVIO_ATT_ADDITIONAL_MAX_LEN) |
| return -EINVAL; |
| if (uvio_attest->reserved136) |
| return -EINVAL; |
| return 0; |
| } |
| |
| /** |
| * uvio_attestation() - Perform a Retrieve Attestation Measurement UVC. |
| * |
| * @uv_ioctl: ioctl control block |
| * |
| * uvio_attestation() does a Retrieve Attestation Measurement Ultravisor Call. |
| * It verifies that the given userspace addresses are valid and request sizes |
| * are sane. Every other check is made by the Ultravisor (UV) and won't result |
| * in a negative return value. It copies the input to kernelspace, builds the |
| * request, sends the UV-call, and copies the result to userspace. |
| * |
| * The Attestation Request has two input and two outputs. |
| * ARCB and User Data are inputs for the UV generated by userspace. |
| * Measurement and Additional Data are outputs for userspace generated by UV. |
| * |
| * The Attestation Request Control Block (ARCB) is a cryptographically verified |
| * and secured request to UV and User Data is some plaintext data which is |
| * going to be included in the Attestation Measurement calculation. |
| * |
| * Measurement is a cryptographic measurement of the callers properties, |
| * optional data configured by the ARCB and the user data. If specified by the |
| * ARCB, UV will add some Additional Data to the measurement calculation. |
| * This Additional Data is then returned as well. |
| * |
| * If the Retrieve Attestation Measurement UV facility is not present, |
| * UV will return invalid command rc. This won't be fenced in the driver |
| * and does not result in a negative return value. |
| * |
| * Context: might sleep |
| * |
| * Return: 0 on success or a negative error code on error. |
| */ |
| static int uvio_attestation(struct uvio_ioctl_cb *uv_ioctl) |
| { |
| struct uv_cb_attest *uvcb_attest = NULL; |
| struct uvio_attest *uvio_attest = NULL; |
| u8 *measurement = NULL; |
| u8 *add_data = NULL; |
| u8 *arcb = NULL; |
| int ret; |
| |
| ret = -EINVAL; |
| if (uv_ioctl->argument_len != sizeof(*uvio_attest)) |
| goto out; |
| |
| ret = -ENOMEM; |
| uvio_attest = kzalloc(sizeof(*uvio_attest), GFP_KERNEL); |
| if (!uvio_attest) |
| goto out; |
| |
| ret = get_uvio_attest(uv_ioctl, uvio_attest); |
| if (ret) |
| goto out; |
| |
| ret = -ENOMEM; |
| arcb = kvzalloc(uvio_attest->arcb_len, GFP_KERNEL); |
| measurement = kvzalloc(uvio_attest->meas_len, GFP_KERNEL); |
| if (!arcb || !measurement) |
| goto out; |
| |
| if (uvio_attest->add_data_len) { |
| add_data = kvzalloc(uvio_attest->add_data_len, GFP_KERNEL); |
| if (!add_data) |
| goto out; |
| } |
| |
| uvcb_attest = kzalloc(sizeof(*uvcb_attest), GFP_KERNEL); |
| if (!uvcb_attest) |
| goto out; |
| |
| ret = uvio_build_uvcb_attest(uvcb_attest, arcb, measurement, add_data, uvio_attest); |
| if (ret) |
| goto out; |
| |
| uv_call_sched(0, (u64)uvcb_attest); |
| |
| uv_ioctl->uv_rc = uvcb_attest->header.rc; |
| uv_ioctl->uv_rrc = uvcb_attest->header.rrc; |
| |
| ret = uvio_copy_attest_result_to_user(uvcb_attest, uv_ioctl, measurement, add_data, |
| uvio_attest); |
| out: |
| kvfree(arcb); |
| kvfree(measurement); |
| kvfree(add_data); |
| kfree(uvio_attest); |
| kfree(uvcb_attest); |
| return ret; |
| } |
| |
| static int uvio_copy_and_check_ioctl(struct uvio_ioctl_cb *ioctl, void __user *argp) |
| { |
| if (copy_from_user(ioctl, argp, sizeof(*ioctl))) |
| return -EFAULT; |
| if (ioctl->flags != 0) |
| return -EINVAL; |
| if (memchr_inv(ioctl->reserved14, 0, sizeof(ioctl->reserved14))) |
| return -EINVAL; |
| |
| return 0; |
| } |
| |
| /* |
| * IOCTL entry point for the Ultravisor device. |
| */ |
| static long uvio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) |
| { |
| void __user *argp = (void __user *)arg; |
| struct uvio_ioctl_cb uv_ioctl = { }; |
| long ret; |
| |
| switch (cmd) { |
| case UVIO_IOCTL_ATT: |
| ret = uvio_copy_and_check_ioctl(&uv_ioctl, argp); |
| if (ret) |
| return ret; |
| ret = uvio_attestation(&uv_ioctl); |
| break; |
| default: |
| ret = -ENOIOCTLCMD; |
| break; |
| } |
| if (ret) |
| return ret; |
| |
| if (copy_to_user(argp, &uv_ioctl, sizeof(uv_ioctl))) |
| ret = -EFAULT; |
| |
| return ret; |
| } |
| |
| static const struct file_operations uvio_dev_fops = { |
| .owner = THIS_MODULE, |
| .unlocked_ioctl = uvio_ioctl, |
| .llseek = no_llseek, |
| }; |
| |
| static struct miscdevice uvio_dev_miscdev = { |
| .minor = MISC_DYNAMIC_MINOR, |
| .name = UVIO_DEVICE_NAME, |
| .fops = &uvio_dev_fops, |
| }; |
| |
| static void __exit uvio_dev_exit(void) |
| { |
| misc_deregister(&uvio_dev_miscdev); |
| } |
| |
| static int __init uvio_dev_init(void) |
| { |
| if (!test_facility(158)) |
| return -ENXIO; |
| return misc_register(&uvio_dev_miscdev); |
| } |
| |
| module_init(uvio_dev_init); |
| module_exit(uvio_dev_exit); |
| |
| MODULE_AUTHOR("IBM Corporation"); |
| MODULE_LICENSE("GPL"); |
| MODULE_DESCRIPTION("Ultravisor UAPI driver"); |