diff options
Diffstat (limited to 'drivers/s390/char/uvdevice.c')
| -rw-r--r-- | drivers/s390/char/uvdevice.c | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/drivers/s390/char/uvdevice.c b/drivers/s390/char/uvdevice.c new file mode 100644 index 000000000..1d40457c7 --- /dev/null +++ b/drivers/s390/char/uvdevice.c @@ -0,0 +1,256 @@ +// 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 <linux/cpufeature.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) +{ + return misc_register(&uvio_dev_miscdev); +} + +module_cpu_feature_match(S390_CPU_FEATURE_UV, uvio_dev_init); +module_exit(uvio_dev_exit); + +MODULE_AUTHOR("IBM Corporation"); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Ultravisor UAPI driver"); |