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-rw-r--r--drivers/s390/char/uvdevice.c256
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");