diff options
Diffstat (limited to 'drivers/virt')
| -rw-r--r-- | drivers/virt/Kconfig | 2 | ||||
| -rw-r--r-- | drivers/virt/Makefile | 1 | ||||
| -rw-r--r-- | drivers/virt/coco/sev-guest/sev-guest.c | 84 | ||||
| -rw-r--r-- | drivers/virt/coco/tdx-guest/Kconfig | 10 | ||||
| -rw-r--r-- | drivers/virt/coco/tdx-guest/Makefile | 2 | ||||
| -rw-r--r-- | drivers/virt/coco/tdx-guest/tdx-guest.c | 102 |
6 files changed, 187 insertions, 14 deletions
diff --git a/drivers/virt/Kconfig b/drivers/virt/Kconfig index 87ef258cec64..f79ab13a5c28 100644 --- a/drivers/virt/Kconfig +++ b/drivers/virt/Kconfig @@ -52,4 +52,6 @@ source "drivers/virt/coco/efi_secret/Kconfig" source "drivers/virt/coco/sev-guest/Kconfig" +source "drivers/virt/coco/tdx-guest/Kconfig" + endif diff --git a/drivers/virt/Makefile b/drivers/virt/Makefile index 093674e05c40..e9aa6fc96fab 100644 --- a/drivers/virt/Makefile +++ b/drivers/virt/Makefile @@ -11,3 +11,4 @@ obj-$(CONFIG_NITRO_ENCLAVES) += nitro_enclaves/ obj-$(CONFIG_ACRN_HSM) += acrn/ obj-$(CONFIG_EFI_SECRET) += coco/efi_secret/ obj-$(CONFIG_SEV_GUEST) += coco/sev-guest/ +obj-$(CONFIG_INTEL_TDX_GUEST) += coco/tdx-guest/ diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c index f422f9c58ba7..1ea6d2e5b218 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -67,8 +67,27 @@ static bool is_vmpck_empty(struct snp_guest_dev *snp_dev) return true; } +/* + * If an error is received from the host or AMD Secure Processor (ASP) there + * are two options. Either retry the exact same encrypted request or discontinue + * using the VMPCK. + * + * This is because in the current encryption scheme GHCB v2 uses AES-GCM to + * encrypt the requests. The IV for this scheme is the sequence number. GCM + * cannot tolerate IV reuse. + * + * The ASP FW v1.51 only increments the sequence numbers on a successful + * guest<->ASP back and forth and only accepts messages at its exact sequence + * number. + * + * So if the sequence number were to be reused the encryption scheme is + * vulnerable. If the sequence number were incremented for a fresh IV the ASP + * will reject the request. + */ static void snp_disable_vmpck(struct snp_guest_dev *snp_dev) { + dev_alert(snp_dev->dev, "Disabling vmpck_id %d to prevent IV reuse.\n", + vmpck_id); memzero_explicit(snp_dev->vmpck, VMPCK_KEY_LEN); snp_dev->vmpck = NULL; } @@ -321,34 +340,71 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in if (rc) return rc; - /* Call firmware to process the request */ + /* + * Call firmware to process the request. In this function the encrypted + * message enters shared memory with the host. So after this call the + * sequence number must be incremented or the VMPCK must be deleted to + * prevent reuse of the IV. + */ rc = snp_issue_guest_request(exit_code, &snp_dev->input, &err); + + /* + * If the extended guest request fails due to having too small of a + * certificate data buffer, retry the same guest request without the + * extended data request in order to increment the sequence number + * and thus avoid IV reuse. + */ + if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST && + err == SNP_GUEST_REQ_INVALID_LEN) { + const unsigned int certs_npages = snp_dev->input.data_npages; + + exit_code = SVM_VMGEXIT_GUEST_REQUEST; + + /* + * If this call to the firmware succeeds, the sequence number can + * be incremented allowing for continued use of the VMPCK. If + * there is an error reflected in the return value, this value + * is checked further down and the result will be the deletion + * of the VMPCK and the error code being propagated back to the + * user as an ioctl() return code. + */ + rc = snp_issue_guest_request(exit_code, &snp_dev->input, &err); + + /* + * Override the error to inform callers the given extended + * request buffer size was too small and give the caller the + * required buffer size. + */ + err = SNP_GUEST_REQ_INVALID_LEN; + snp_dev->input.data_npages = certs_npages; + } + if (fw_err) *fw_err = err; - if (rc) - return rc; + if (rc) { + dev_alert(snp_dev->dev, + "Detected error from ASP request. rc: %d, fw_err: %llu\n", + rc, *fw_err); + goto disable_vmpck; + } - /* - * The verify_and_dec_payload() will fail only if the hypervisor is - * actively modifying the message header or corrupting the encrypted payload. - * This hints that hypervisor is acting in a bad faith. Disable the VMPCK so that - * the key cannot be used for any communication. The key is disabled to ensure - * that AES-GCM does not use the same IV while encrypting the request payload. - */ rc = verify_and_dec_payload(snp_dev, resp_buf, resp_sz); if (rc) { dev_alert(snp_dev->dev, - "Detected unexpected decode failure, disabling the vmpck_id %d\n", - vmpck_id); - snp_disable_vmpck(snp_dev); - return rc; + "Detected unexpected decode failure from ASP. rc: %d\n", + rc); + goto disable_vmpck; } /* Increment to new message sequence after payload decryption was successful. */ snp_inc_msg_seqno(snp_dev); return 0; + +disable_vmpck: + snp_disable_vmpck(snp_dev); + return rc; } static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg) diff --git a/drivers/virt/coco/tdx-guest/Kconfig b/drivers/virt/coco/tdx-guest/Kconfig new file mode 100644 index 000000000000..14246fc2fb02 --- /dev/null +++ b/drivers/virt/coco/tdx-guest/Kconfig @@ -0,0 +1,10 @@ +config TDX_GUEST_DRIVER + tristate "TDX Guest driver" + depends on INTEL_TDX_GUEST + help + The driver provides userspace interface to communicate with + the TDX module to request the TDX guest details like attestation + report. + + To compile this driver as module, choose M here. The module will + be called tdx-guest. diff --git a/drivers/virt/coco/tdx-guest/Makefile b/drivers/virt/coco/tdx-guest/Makefile new file mode 100644 index 000000000000..775cb463f9c8 --- /dev/null +++ b/drivers/virt/coco/tdx-guest/Makefile @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0 +obj-$(CONFIG_TDX_GUEST_DRIVER) += tdx-guest.o diff --git a/drivers/virt/coco/tdx-guest/tdx-guest.c b/drivers/virt/coco/tdx-guest/tdx-guest.c new file mode 100644 index 000000000000..5e44a0fa69bd --- /dev/null +++ b/drivers/virt/coco/tdx-guest/tdx-guest.c @@ -0,0 +1,102 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * TDX guest user interface driver + * + * Copyright (C) 2022 Intel Corporation + */ + +#include <linux/kernel.h> +#include <linux/miscdevice.h> +#include <linux/mm.h> +#include <linux/module.h> +#include <linux/mod_devicetable.h> +#include <linux/string.h> +#include <linux/uaccess.h> + +#include <uapi/linux/tdx-guest.h> + +#include <asm/cpu_device_id.h> +#include <asm/tdx.h> + +static long tdx_get_report0(struct tdx_report_req __user *req) +{ + u8 *reportdata, *tdreport; + long ret; + + reportdata = kmalloc(TDX_REPORTDATA_LEN, GFP_KERNEL); + if (!reportdata) + return -ENOMEM; + + tdreport = kzalloc(TDX_REPORT_LEN, GFP_KERNEL); + if (!tdreport) { + ret = -ENOMEM; + goto out; + } + + if (copy_from_user(reportdata, req->reportdata, TDX_REPORTDATA_LEN)) { + ret = -EFAULT; + goto out; + } + + /* Generate TDREPORT0 using "TDG.MR.REPORT" TDCALL */ + ret = tdx_mcall_get_report0(reportdata, tdreport); + if (ret) + goto out; + + if (copy_to_user(req->tdreport, tdreport, TDX_REPORT_LEN)) + ret = -EFAULT; + +out: + kfree(reportdata); + kfree(tdreport); + + return ret; +} + +static long tdx_guest_ioctl(struct file *file, unsigned int cmd, + unsigned long arg) +{ + switch (cmd) { + case TDX_CMD_GET_REPORT0: + return tdx_get_report0((struct tdx_report_req __user *)arg); + default: + return -ENOTTY; + } +} + +static const struct file_operations tdx_guest_fops = { + .owner = THIS_MODULE, + .unlocked_ioctl = tdx_guest_ioctl, + .llseek = no_llseek, +}; + +static struct miscdevice tdx_misc_dev = { + .name = KBUILD_MODNAME, + .minor = MISC_DYNAMIC_MINOR, + .fops = &tdx_guest_fops, +}; + +static const struct x86_cpu_id tdx_guest_ids[] = { + X86_MATCH_FEATURE(X86_FEATURE_TDX_GUEST, NULL), + {} +}; +MODULE_DEVICE_TABLE(x86cpu, tdx_guest_ids); + +static int __init tdx_guest_init(void) +{ + if (!x86_match_cpu(tdx_guest_ids)) + return -ENODEV; + + return misc_register(&tdx_misc_dev); +} +module_init(tdx_guest_init); + +static void __exit tdx_guest_exit(void) +{ + misc_deregister(&tdx_misc_dev); +} +module_exit(tdx_guest_exit); + +MODULE_AUTHOR("Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>"); +MODULE_DESCRIPTION("TDX Guest Driver"); +MODULE_LICENSE("GPL"); |