1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright IBM Corp. 2022 4 * Author(s): Steffen Eiden <seiden@linux.ibm.com> 5 * 6 * This file provides a Linux misc device to give userspace access to some 7 * Ultravisor (UV) functions. The device only accepts IOCTLs and will only 8 * be present if the Ultravisor facility (158) is present. 9 * 10 * When userspace sends a valid IOCTL uvdevice will copy the input data to 11 * kernel space, do some basic validity checks to avoid kernel/system 12 * corruption. Any other check that the Ultravisor does will not be done by 13 * the uvdevice to keep changes minimal when adding new functionalities 14 * to existing UV-calls. 15 * After the checks uvdevice builds a corresponding 16 * Ultravisor Call Control Block, and sends the request to the Ultravisor. 17 * Then, it copies the response, including the return codes, back to userspace. 18 * It is the responsibility of the userspace to check for any error issued 19 * by UV and to interpret the UV response. The uvdevice acts as a communication 20 * channel for userspace to the Ultravisor. 21 */ 22 23 #include <linux/module.h> 24 #include <linux/kernel.h> 25 #include <linux/miscdevice.h> 26 #include <linux/types.h> 27 #include <linux/stddef.h> 28 #include <linux/vmalloc.h> 29 #include <linux/slab.h> 30 31 #include <asm/uvdevice.h> 32 #include <asm/uv.h> 33 34 static int uvio_build_uvcb_attest(struct uv_cb_attest *uvcb_attest, u8 *arcb, 35 u8 *meas, u8 *add_data, struct uvio_attest *uvio_attest) 36 { 37 void __user *user_buf_arcb = (void __user *)uvio_attest->arcb_addr; 38 39 if (copy_from_user(arcb, user_buf_arcb, uvio_attest->arcb_len)) 40 return -EFAULT; 41 42 uvcb_attest->header.len = sizeof(*uvcb_attest); 43 uvcb_attest->header.cmd = UVC_CMD_RETR_ATTEST; 44 uvcb_attest->arcb_addr = (u64)arcb; 45 uvcb_attest->cont_token = 0; 46 uvcb_attest->user_data_len = uvio_attest->user_data_len; 47 memcpy(uvcb_attest->user_data, uvio_attest->user_data, sizeof(uvcb_attest->user_data)); 48 uvcb_attest->meas_len = uvio_attest->meas_len; 49 uvcb_attest->meas_addr = (u64)meas; 50 uvcb_attest->add_data_len = uvio_attest->add_data_len; 51 uvcb_attest->add_data_addr = (u64)add_data; 52 53 return 0; 54 } 55 56 static int uvio_copy_attest_result_to_user(struct uv_cb_attest *uvcb_attest, 57 struct uvio_ioctl_cb *uv_ioctl, 58 u8 *measurement, u8 *add_data, 59 struct uvio_attest *uvio_attest) 60 { 61 struct uvio_attest __user *user_uvio_attest = (void __user *)uv_ioctl->argument_addr; 62 void __user *user_buf_add = (void __user *)uvio_attest->add_data_addr; 63 void __user *user_buf_meas = (void __user *)uvio_attest->meas_addr; 64 void __user *user_buf_uid = &user_uvio_attest->config_uid; 65 66 if (copy_to_user(user_buf_meas, measurement, uvio_attest->meas_len)) 67 return -EFAULT; 68 if (add_data && copy_to_user(user_buf_add, add_data, uvio_attest->add_data_len)) 69 return -EFAULT; 70 if (copy_to_user(user_buf_uid, uvcb_attest->config_uid, sizeof(uvcb_attest->config_uid))) 71 return -EFAULT; 72 return 0; 73 } 74 75 static int get_uvio_attest(struct uvio_ioctl_cb *uv_ioctl, struct uvio_attest *uvio_attest) 76 { 77 u8 __user *user_arg_buf = (u8 __user *)uv_ioctl->argument_addr; 78 79 if (copy_from_user(uvio_attest, user_arg_buf, sizeof(*uvio_attest))) 80 return -EFAULT; 81 82 if (uvio_attest->arcb_len > UVIO_ATT_ARCB_MAX_LEN) 83 return -EINVAL; 84 if (uvio_attest->arcb_len == 0) 85 return -EINVAL; 86 if (uvio_attest->meas_len > UVIO_ATT_MEASUREMENT_MAX_LEN) 87 return -EINVAL; 88 if (uvio_attest->meas_len == 0) 89 return -EINVAL; 90 if (uvio_attest->add_data_len > UVIO_ATT_ADDITIONAL_MAX_LEN) 91 return -EINVAL; 92 if (uvio_attest->reserved136) 93 return -EINVAL; 94 return 0; 95 } 96 97 /** 98 * uvio_attestation() - Perform a Retrieve Attestation Measurement UVC. 99 * 100 * @uv_ioctl: ioctl control block 101 * 102 * uvio_attestation() does a Retrieve Attestation Measurement Ultravisor Call. 103 * It verifies that the given userspace addresses are valid and request sizes 104 * are sane. Every other check is made by the Ultravisor (UV) and won't result 105 * in a negative return value. It copies the input to kernelspace, builds the 106 * request, sends the UV-call, and copies the result to userspace. 107 * 108 * The Attestation Request has two input and two outputs. 109 * ARCB and User Data are inputs for the UV generated by userspace. 110 * Measurement and Additional Data are outputs for userspace generated by UV. 111 * 112 * The Attestation Request Control Block (ARCB) is a cryptographically verified 113 * and secured request to UV and User Data is some plaintext data which is 114 * going to be included in the Attestation Measurement calculation. 115 * 116 * Measurement is a cryptographic measurement of the callers properties, 117 * optional data configured by the ARCB and the user data. If specified by the 118 * ARCB, UV will add some Additional Data to the measurement calculation. 119 * This Additional Data is then returned as well. 120 * 121 * If the Retrieve Attestation Measurement UV facility is not present, 122 * UV will return invalid command rc. This won't be fenced in the driver 123 * and does not result in a negative return value. 124 * 125 * Context: might sleep 126 * 127 * Return: 0 on success or a negative error code on error. 128 */ 129 static int uvio_attestation(struct uvio_ioctl_cb *uv_ioctl) 130 { 131 struct uv_cb_attest *uvcb_attest = NULL; 132 struct uvio_attest *uvio_attest = NULL; 133 u8 *measurement = NULL; 134 u8 *add_data = NULL; 135 u8 *arcb = NULL; 136 int ret; 137 138 ret = -EINVAL; 139 if (uv_ioctl->argument_len != sizeof(*uvio_attest)) 140 goto out; 141 142 ret = -ENOMEM; 143 uvio_attest = kzalloc(sizeof(*uvio_attest), GFP_KERNEL); 144 if (!uvio_attest) 145 goto out; 146 147 ret = get_uvio_attest(uv_ioctl, uvio_attest); 148 if (ret) 149 goto out; 150 151 ret = -ENOMEM; 152 arcb = kvzalloc(uvio_attest->arcb_len, GFP_KERNEL); 153 measurement = kvzalloc(uvio_attest->meas_len, GFP_KERNEL); 154 if (!arcb || !measurement) 155 goto out; 156 157 if (uvio_attest->add_data_len) { 158 add_data = kvzalloc(uvio_attest->add_data_len, GFP_KERNEL); 159 if (!add_data) 160 goto out; 161 } 162 163 uvcb_attest = kzalloc(sizeof(*uvcb_attest), GFP_KERNEL); 164 if (!uvcb_attest) 165 goto out; 166 167 ret = uvio_build_uvcb_attest(uvcb_attest, arcb, measurement, add_data, uvio_attest); 168 if (ret) 169 goto out; 170 171 uv_call_sched(0, (u64)uvcb_attest); 172 173 uv_ioctl->uv_rc = uvcb_attest->header.rc; 174 uv_ioctl->uv_rrc = uvcb_attest->header.rrc; 175 176 ret = uvio_copy_attest_result_to_user(uvcb_attest, uv_ioctl, measurement, add_data, 177 uvio_attest); 178 out: 179 kvfree(arcb); 180 kvfree(measurement); 181 kvfree(add_data); 182 kfree(uvio_attest); 183 kfree(uvcb_attest); 184 return ret; 185 } 186 187 static int uvio_copy_and_check_ioctl(struct uvio_ioctl_cb *ioctl, void __user *argp) 188 { 189 if (copy_from_user(ioctl, argp, sizeof(*ioctl))) 190 return -EFAULT; 191 if (ioctl->flags != 0) 192 return -EINVAL; 193 if (memchr_inv(ioctl->reserved14, 0, sizeof(ioctl->reserved14))) 194 return -EINVAL; 195 196 return 0; 197 } 198 199 /* 200 * IOCTL entry point for the Ultravisor device. 201 */ 202 static long uvio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 203 { 204 void __user *argp = (void __user *)arg; 205 struct uvio_ioctl_cb uv_ioctl = { }; 206 long ret; 207 208 switch (cmd) { 209 case UVIO_IOCTL_ATT: 210 ret = uvio_copy_and_check_ioctl(&uv_ioctl, argp); 211 if (ret) 212 return ret; 213 ret = uvio_attestation(&uv_ioctl); 214 break; 215 default: 216 ret = -ENOIOCTLCMD; 217 break; 218 } 219 if (ret) 220 return ret; 221 222 if (copy_to_user(argp, &uv_ioctl, sizeof(uv_ioctl))) 223 ret = -EFAULT; 224 225 return ret; 226 } 227 228 static const struct file_operations uvio_dev_fops = { 229 .owner = THIS_MODULE, 230 .unlocked_ioctl = uvio_ioctl, 231 .llseek = no_llseek, 232 }; 233 234 static struct miscdevice uvio_dev_miscdev = { 235 .minor = MISC_DYNAMIC_MINOR, 236 .name = UVIO_DEVICE_NAME, 237 .fops = &uvio_dev_fops, 238 }; 239 240 static void __exit uvio_dev_exit(void) 241 { 242 misc_deregister(&uvio_dev_miscdev); 243 } 244 245 static int __init uvio_dev_init(void) 246 { 247 if (!test_facility(158)) 248 return -ENXIO; 249 return misc_register(&uvio_dev_miscdev); 250 } 251 252 module_init(uvio_dev_init); 253 module_exit(uvio_dev_exit); 254 255 MODULE_AUTHOR("IBM Corporation"); 256 MODULE_LICENSE("GPL"); 257 MODULE_DESCRIPTION("Ultravisor UAPI driver"); 258