diff options
Diffstat (limited to 'drivers/virt/coco/sev-guest/sev-guest.c')
| -rw-r--r-- | drivers/virt/coco/sev-guest/sev-guest.c | 715 |
1 files changed, 715 insertions, 0 deletions
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c new file mode 100644 index 000000000000..b01ec99106cd --- /dev/null +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -0,0 +1,715 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * AMD Secure Encrypted Virtualization (SEV) guest driver interface + * + * Copyright (C) 2021-2024 Advanced Micro Devices, Inc. + * + * Author: Brijesh Singh <brijesh.singh@amd.com> + */ + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/types.h> +#include <linux/mutex.h> +#include <linux/io.h> +#include <linux/platform_device.h> +#include <linux/miscdevice.h> +#include <linux/set_memory.h> +#include <linux/fs.h> +#include <linux/tsm.h> +#include <crypto/gcm.h> +#include <linux/psp-sev.h> +#include <linux/sockptr.h> +#include <linux/cleanup.h> +#include <linux/uuid.h> +#include <linux/configfs.h> +#include <linux/mm.h> +#include <uapi/linux/sev-guest.h> +#include <uapi/linux/psp-sev.h> + +#include <asm/svm.h> +#include <asm/sev.h> + +#define DEVICE_NAME "sev-guest" + +#define SVSM_MAX_RETRIES 3 + +struct snp_guest_dev { + struct device *dev; + struct miscdevice misc; + + struct snp_msg_desc *msg_desc; +}; + +/* + * The VMPCK ID represents the key used by the SNP guest to communicate with the + * SEV firmware in the AMD Secure Processor (ASP, aka PSP). By default, the key + * used will be the key associated with the VMPL at which the guest is running. + * Should the default key be wiped (see snp_disable_vmpck()), this parameter + * allows for using one of the remaining VMPCKs. + */ +static int vmpck_id = -1; +module_param(vmpck_id, int, 0444); +MODULE_PARM_DESC(vmpck_id, "The VMPCK ID to use when communicating with the PSP."); + +static inline struct snp_guest_dev *to_snp_dev(struct file *file) +{ + struct miscdevice *dev = file->private_data; + + return container_of(dev, struct snp_guest_dev, misc); +} + +struct snp_req_resp { + sockptr_t req_data; + sockptr_t resp_data; +}; + +static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg) +{ + struct snp_report_req *report_req __free(kfree) = NULL; + struct snp_msg_desc *mdesc = snp_dev->msg_desc; + struct snp_report_resp *report_resp; + struct snp_guest_req req = {}; + int rc, resp_len; + + if (!arg->req_data || !arg->resp_data) + return -EINVAL; + + report_req = kzalloc(sizeof(*report_req), GFP_KERNEL_ACCOUNT); + if (!report_req) + return -ENOMEM; + + if (copy_from_user(report_req, (void __user *)arg->req_data, sizeof(*report_req))) + return -EFAULT; + + /* + * The intermediate response buffer is used while decrypting the + * response payload. Make sure that it has enough space to cover the + * authtag. + */ + resp_len = sizeof(report_resp->data) + mdesc->ctx->authsize; + report_resp = kzalloc(resp_len, GFP_KERNEL_ACCOUNT); + if (!report_resp) + return -ENOMEM; + + req.msg_version = arg->msg_version; + req.msg_type = SNP_MSG_REPORT_REQ; + req.vmpck_id = mdesc->vmpck_id; + req.req_buf = report_req; + req.req_sz = sizeof(*report_req); + req.resp_buf = report_resp->data; + req.resp_sz = resp_len; + req.exit_code = SVM_VMGEXIT_GUEST_REQUEST; + + rc = snp_send_guest_request(mdesc, &req); + arg->exitinfo2 = req.exitinfo2; + if (rc) + goto e_free; + + if (copy_to_user((void __user *)arg->resp_data, report_resp, sizeof(*report_resp))) + rc = -EFAULT; + +e_free: + kfree(report_resp); + return rc; +} + +static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg) +{ + struct snp_derived_key_resp *derived_key_resp __free(kfree) = NULL; + struct snp_derived_key_req *derived_key_req __free(kfree) = NULL; + struct snp_msg_desc *mdesc = snp_dev->msg_desc; + struct snp_guest_req req = {}; + int rc, resp_len; + + if (!arg->req_data || !arg->resp_data) + return -EINVAL; + + /* + * The intermediate response buffer is used while decrypting the + * response payload. Make sure that it has enough space to cover the + * authtag. + */ + resp_len = sizeof(derived_key_resp->data) + mdesc->ctx->authsize; + derived_key_resp = kzalloc(resp_len, GFP_KERNEL_ACCOUNT); + if (!derived_key_resp) + return -ENOMEM; + + derived_key_req = kzalloc(sizeof(*derived_key_req), GFP_KERNEL_ACCOUNT); + if (!derived_key_req) + return -ENOMEM; + + if (copy_from_user(derived_key_req, (void __user *)arg->req_data, + sizeof(*derived_key_req))) + return -EFAULT; + + req.msg_version = arg->msg_version; + req.msg_type = SNP_MSG_KEY_REQ; + req.vmpck_id = mdesc->vmpck_id; + req.req_buf = derived_key_req; + req.req_sz = sizeof(*derived_key_req); + req.resp_buf = derived_key_resp; + req.resp_sz = resp_len; + req.exit_code = SVM_VMGEXIT_GUEST_REQUEST; + + rc = snp_send_guest_request(mdesc, &req); + arg->exitinfo2 = req.exitinfo2; + if (!rc) { + if (copy_to_user((void __user *)arg->resp_data, derived_key_resp, + sizeof(derived_key_resp->data))) + rc = -EFAULT; + } + + /* The response buffer contains the sensitive data, explicitly clear it. */ + memzero_explicit(derived_key_resp, sizeof(*derived_key_resp)); + + return rc; +} + +static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg, + struct snp_req_resp *io) + +{ + struct snp_ext_report_req *report_req __free(kfree) = NULL; + struct snp_msg_desc *mdesc = snp_dev->msg_desc; + struct snp_report_resp *report_resp; + struct snp_guest_req req = {}; + int ret, npages = 0, resp_len; + sockptr_t certs_address; + struct page *page; + + if (sockptr_is_null(io->req_data) || sockptr_is_null(io->resp_data)) + return -EINVAL; + + report_req = kzalloc(sizeof(*report_req), GFP_KERNEL_ACCOUNT); + if (!report_req) + return -ENOMEM; + + if (copy_from_sockptr(report_req, io->req_data, sizeof(*report_req))) + return -EFAULT; + + /* caller does not want certificate data */ + if (!report_req->certs_len || !report_req->certs_address) + goto cmd; + + if (report_req->certs_len > SEV_FW_BLOB_MAX_SIZE || + !IS_ALIGNED(report_req->certs_len, PAGE_SIZE)) + return -EINVAL; + + if (sockptr_is_kernel(io->resp_data)) { + certs_address = KERNEL_SOCKPTR((void *)report_req->certs_address); + } else { + certs_address = USER_SOCKPTR((void __user *)report_req->certs_address); + if (!access_ok(certs_address.user, report_req->certs_len)) + return -EFAULT; + } + + /* + * Initialize the intermediate buffer with all zeros. This buffer + * is used in the guest request message to get the certs blob from + * the host. If host does not supply any certs in it, then copy + * zeros to indicate that certificate data was not provided. + */ + npages = report_req->certs_len >> PAGE_SHIFT; + page = alloc_pages(GFP_KERNEL_ACCOUNT | __GFP_ZERO, + get_order(report_req->certs_len)); + if (!page) + return -ENOMEM; + + req.certs_data = page_address(page); + ret = set_memory_decrypted((unsigned long)req.certs_data, npages); + if (ret) { + pr_err("failed to mark page shared, ret=%d\n", ret); + __free_pages(page, get_order(report_req->certs_len)); + return -EFAULT; + } + +cmd: + /* + * The intermediate response buffer is used while decrypting the + * response payload. Make sure that it has enough space to cover the + * authtag. + */ + resp_len = sizeof(report_resp->data) + mdesc->ctx->authsize; + report_resp = kzalloc(resp_len, GFP_KERNEL_ACCOUNT); + if (!report_resp) { + ret = -ENOMEM; + goto e_free_data; + } + + req.input.data_npages = npages; + + req.msg_version = arg->msg_version; + req.msg_type = SNP_MSG_REPORT_REQ; + req.vmpck_id = mdesc->vmpck_id; + req.req_buf = &report_req->data; + req.req_sz = sizeof(report_req->data); + req.resp_buf = report_resp->data; + req.resp_sz = resp_len; + req.exit_code = SVM_VMGEXIT_EXT_GUEST_REQUEST; + + ret = snp_send_guest_request(mdesc, &req); + arg->exitinfo2 = req.exitinfo2; + + /* If certs length is invalid then copy the returned length */ + if (arg->vmm_error == SNP_GUEST_VMM_ERR_INVALID_LEN) { + report_req->certs_len = req.input.data_npages << PAGE_SHIFT; + + if (copy_to_sockptr(io->req_data, report_req, sizeof(*report_req))) + ret = -EFAULT; + } + + if (ret) + goto e_free; + + if (npages && copy_to_sockptr(certs_address, req.certs_data, report_req->certs_len)) { + ret = -EFAULT; + goto e_free; + } + + if (copy_to_sockptr(io->resp_data, report_resp, sizeof(*report_resp))) + ret = -EFAULT; + +e_free: + kfree(report_resp); +e_free_data: + if (npages) { + if (set_memory_encrypted((unsigned long)req.certs_data, npages)) + WARN_ONCE(ret, "failed to restore encryption mask (leak it)\n"); + else + __free_pages(page, get_order(report_req->certs_len)); + } + return ret; +} + +static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long arg) +{ + struct snp_guest_dev *snp_dev = to_snp_dev(file); + void __user *argp = (void __user *)arg; + struct snp_guest_request_ioctl input; + struct snp_req_resp io; + int ret = -ENOTTY; + + if (copy_from_user(&input, argp, sizeof(input))) + return -EFAULT; + + input.exitinfo2 = 0xff; + + /* Message version must be non-zero */ + if (!input.msg_version) + return -EINVAL; + + switch (ioctl) { + case SNP_GET_REPORT: + ret = get_report(snp_dev, &input); + break; + case SNP_GET_DERIVED_KEY: + ret = get_derived_key(snp_dev, &input); + break; + case SNP_GET_EXT_REPORT: + /* + * As get_ext_report() may be called from the ioctl() path and a + * kernel internal path (configfs-tsm), decorate the passed + * buffers as user pointers. + */ + io.req_data = USER_SOCKPTR((void __user *)input.req_data); + io.resp_data = USER_SOCKPTR((void __user *)input.resp_data); + ret = get_ext_report(snp_dev, &input, &io); + break; + default: + break; + } + + if (input.exitinfo2 && copy_to_user(argp, &input, sizeof(input))) + return -EFAULT; + + return ret; +} + +static const struct file_operations snp_guest_fops = { + .owner = THIS_MODULE, + .unlocked_ioctl = snp_guest_ioctl, +}; + +struct snp_msg_report_resp_hdr { + u32 status; + u32 report_size; + u8 rsvd[24]; +}; + +struct snp_msg_cert_entry { + guid_t guid; + u32 offset; + u32 length; +}; + +static int sev_svsm_report_new(struct tsm_report *report, void *data) +{ + unsigned int rep_len, man_len, certs_len; + struct tsm_report_desc *desc = &report->desc; + struct svsm_attest_call ac = {}; + unsigned int retry_count; + void *rep, *man, *certs; + struct svsm_call call; + unsigned int size; + bool try_again; + void *buffer; + u64 call_id; + int ret; + + /* + * Allocate pages for the request: + * - Report blob (4K) + * - Manifest blob (4K) + * - Certificate blob (16K) + * + * Above addresses must be 4K aligned + */ + rep_len = SZ_4K; + man_len = SZ_4K; + certs_len = SEV_FW_BLOB_MAX_SIZE; + + if (guid_is_null(&desc->service_guid)) { + call_id = SVSM_ATTEST_CALL(SVSM_ATTEST_SERVICES); + } else { + export_guid(ac.service_guid, &desc->service_guid); + ac.service_manifest_ver = desc->service_manifest_version; + + call_id = SVSM_ATTEST_CALL(SVSM_ATTEST_SINGLE_SERVICE); + } + + retry_count = 0; + +retry: + memset(&call, 0, sizeof(call)); + + size = rep_len + man_len + certs_len; + buffer = alloc_pages_exact(size, __GFP_ZERO); + if (!buffer) + return -ENOMEM; + + rep = buffer; + ac.report_buf.pa = __pa(rep); + ac.report_buf.len = rep_len; + + man = rep + rep_len; + ac.manifest_buf.pa = __pa(man); + ac.manifest_buf.len = man_len; + + certs = man + man_len; + ac.certificates_buf.pa = __pa(certs); + ac.certificates_buf.len = certs_len; + + ac.nonce.pa = __pa(desc->inblob); + ac.nonce.len = desc->inblob_len; + + ret = snp_issue_svsm_attest_req(call_id, &call, &ac); + if (ret) { + free_pages_exact(buffer, size); + + switch (call.rax_out) { + case SVSM_ERR_INVALID_PARAMETER: + try_again = false; + + if (ac.report_buf.len > rep_len) { + rep_len = PAGE_ALIGN(ac.report_buf.len); + try_again = true; + } + + if (ac.manifest_buf.len > man_len) { + man_len = PAGE_ALIGN(ac.manifest_buf.len); + try_again = true; + } + + if (ac.certificates_buf.len > certs_len) { + certs_len = PAGE_ALIGN(ac.certificates_buf.len); + try_again = true; + } + + /* If one of the buffers wasn't large enough, retry the request */ + if (try_again && retry_count < SVSM_MAX_RETRIES) { + retry_count++; + goto retry; + } + + return -EINVAL; + default: + pr_err_ratelimited("SVSM attestation request failed (%d / 0x%llx)\n", + ret, call.rax_out); + return -EINVAL; + } + } + + /* + * Allocate all the blob memory buffers at once so that the cleanup is + * done for errors that occur after the first allocation (i.e. before + * using no_free_ptr()). + */ + rep_len = ac.report_buf.len; + void *rbuf __free(kvfree) = kvzalloc(rep_len, GFP_KERNEL); + + man_len = ac.manifest_buf.len; + void *mbuf __free(kvfree) = kvzalloc(man_len, GFP_KERNEL); + + certs_len = ac.certificates_buf.len; + void *cbuf __free(kvfree) = certs_len ? kvzalloc(certs_len, GFP_KERNEL) : NULL; + + if (!rbuf || !mbuf || (certs_len && !cbuf)) { + free_pages_exact(buffer, size); + return -ENOMEM; + } + + memcpy(rbuf, rep, rep_len); + report->outblob = no_free_ptr(rbuf); + report->outblob_len = rep_len; + + memcpy(mbuf, man, man_len); + report->manifestblob = no_free_ptr(mbuf); + report->manifestblob_len = man_len; + + if (certs_len) { + memcpy(cbuf, certs, certs_len); + report->auxblob = no_free_ptr(cbuf); + report->auxblob_len = certs_len; + } + + free_pages_exact(buffer, size); + + return 0; +} + +static int sev_report_new(struct tsm_report *report, void *data) +{ + struct snp_msg_cert_entry *cert_table; + struct tsm_report_desc *desc = &report->desc; + struct snp_guest_dev *snp_dev = data; + struct snp_msg_report_resp_hdr hdr; + const u32 report_size = SZ_4K; + const u32 ext_size = SEV_FW_BLOB_MAX_SIZE; + u32 certs_size, i, size = report_size + ext_size; + int ret; + + if (desc->inblob_len != SNP_REPORT_USER_DATA_SIZE) + return -EINVAL; + + if (desc->service_provider) { + if (strcmp(desc->service_provider, "svsm")) + return -EINVAL; + + return sev_svsm_report_new(report, data); + } + + void *buf __free(kvfree) = kvzalloc(size, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + cert_table = buf + report_size; + struct snp_ext_report_req ext_req = { + .data = { .vmpl = desc->privlevel }, + .certs_address = (__u64)cert_table, + .certs_len = ext_size, + }; + memcpy(&ext_req.data.user_data, desc->inblob, desc->inblob_len); + + struct snp_guest_request_ioctl input = { + .msg_version = 1, + .req_data = (__u64)&ext_req, + .resp_data = (__u64)buf, + .exitinfo2 = 0xff, + }; + struct snp_req_resp io = { + .req_data = KERNEL_SOCKPTR(&ext_req), + .resp_data = KERNEL_SOCKPTR(buf), + }; + + ret = get_ext_report(snp_dev, &input, &io); + if (ret) + return ret; + + memcpy(&hdr, buf, sizeof(hdr)); + if (hdr.status == SEV_RET_INVALID_PARAM) + return -EINVAL; + if (hdr.status == SEV_RET_INVALID_KEY) + return -EINVAL; + if (hdr.status) + return -ENXIO; + if ((hdr.report_size + sizeof(hdr)) > report_size) + return -ENOMEM; + + void *rbuf __free(kvfree) = kvzalloc(hdr.report_size, GFP_KERNEL); + if (!rbuf) + return -ENOMEM; + + memcpy(rbuf, buf + sizeof(hdr), hdr.report_size); + report->outblob = no_free_ptr(rbuf); + report->outblob_len = hdr.report_size; + + certs_size = 0; + for (i = 0; i < ext_size / sizeof(struct snp_msg_cert_entry); i++) { + struct snp_msg_cert_entry *ent = &cert_table[i]; + + if (guid_is_null(&ent->guid) && !ent->offset && !ent->length) + break; + certs_size = max(certs_size, ent->offset + ent->length); + } + + /* Suspicious that the response populated entries without populating size */ + if (!certs_size && i) + dev_warn_ratelimited(snp_dev->dev, "certificate slots conveyed without size\n"); + + /* No certs to report */ + if (!certs_size) + return 0; + + /* Suspicious that the certificate blob size contract was violated + */ + if (certs_size > ext_size) { + dev_warn_ratelimited(snp_dev->dev, "certificate data truncated\n"); + certs_size = ext_size; + } + + void *cbuf __free(kvfree) = kvzalloc(certs_size, GFP_KERNEL); + if (!cbuf) + return -ENOMEM; + + memcpy(cbuf, cert_table, certs_size); + report->auxblob = no_free_ptr(cbuf); + report->auxblob_len = certs_size; + + return 0; +} + +static bool sev_report_attr_visible(int n) +{ + switch (n) { + case TSM_REPORT_GENERATION: + case TSM_REPORT_PROVIDER: + case TSM_REPORT_PRIVLEVEL: + case TSM_REPORT_PRIVLEVEL_FLOOR: + return true; + case TSM_REPORT_SERVICE_PROVIDER: + case TSM_REPORT_SERVICE_GUID: + case TSM_REPORT_SERVICE_MANIFEST_VER: + return snp_vmpl; + } + + return false; +} + +static bool sev_report_bin_attr_visible(int n) +{ + switch (n) { + case TSM_REPORT_INBLOB: + case TSM_REPORT_OUTBLOB: + case TSM_REPORT_AUXBLOB: + return true; + case TSM_REPORT_MANIFESTBLOB: + return snp_vmpl; + } + + return false; +} + +static struct tsm_report_ops sev_tsm_report_ops = { + .name = KBUILD_MODNAME, + .report_new = sev_report_new, + .report_attr_visible = sev_report_attr_visible, + .report_bin_attr_visible = sev_report_bin_attr_visible, +}; + +static void unregister_sev_tsm(void *data) +{ + tsm_report_unregister(&sev_tsm_report_ops); +} + +static int __init sev_guest_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct snp_guest_dev *snp_dev; + struct snp_msg_desc *mdesc; + struct miscdevice *misc; + int ret; + + BUILD_BUG_ON(sizeof(struct snp_guest_msg) > PAGE_SIZE); + + if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) + return -ENODEV; + + snp_dev = devm_kzalloc(&pdev->dev, sizeof(struct snp_guest_dev), GFP_KERNEL); + if (!snp_dev) + return -ENOMEM; + + mdesc = snp_msg_alloc(); + if (IS_ERR_OR_NULL(mdesc)) + return -ENOMEM; + + ret = snp_msg_init(mdesc, vmpck_id); + if (ret) + goto e_msg_init; + + platform_set_drvdata(pdev, snp_dev); + snp_dev->dev = dev; + + misc = &snp_dev->misc; + misc->minor = MISC_DYNAMIC_MINOR; + misc->name = DEVICE_NAME; + misc->fops = &snp_guest_fops; + + /* Set the privlevel_floor attribute based on the vmpck_id */ + sev_tsm_report_ops.privlevel_floor = mdesc->vmpck_id; + + ret = tsm_report_register(&sev_tsm_report_ops, snp_dev); + if (ret) + goto e_msg_init; + + ret = devm_add_action_or_reset(&pdev->dev, unregister_sev_tsm, NULL); + if (ret) + goto e_msg_init; + + ret = misc_register(misc); + if (ret) + goto e_msg_init; + + snp_dev->msg_desc = mdesc; + dev_info(dev, "Initialized SEV guest driver (using VMPCK%d communication key)\n", + mdesc->vmpck_id); + return 0; + +e_msg_init: + snp_msg_free(mdesc); + + return ret; +} + +static void __exit sev_guest_remove(struct platform_device *pdev) +{ + struct snp_guest_dev *snp_dev = platform_get_drvdata(pdev); + + snp_msg_free(snp_dev->msg_desc); + misc_deregister(&snp_dev->misc); +} + +/* + * This driver is meant to be a common SEV guest interface driver and to + * support any SEV guest API. As such, even though it has been introduced + * with the SEV-SNP support, it is named "sev-guest". + * + * sev_guest_remove() lives in .exit.text. For drivers registered via + * module_platform_driver_probe() this is ok because they cannot get unbound + * at runtime. So mark the driver struct with __refdata to prevent modpost + * triggering a section mismatch warning. + */ +static struct platform_driver sev_guest_driver __refdata = { + .remove = __exit_p(sev_guest_remove), + .driver = { + .name = "sev-guest", + }, +}; + +module_platform_driver_probe(sev_guest_driver, sev_guest_probe); + +MODULE_AUTHOR("Brijesh Singh <brijesh.singh@amd.com>"); +MODULE_LICENSE("GPL"); +MODULE_VERSION("1.0.0"); +MODULE_DESCRIPTION("AMD SEV Guest Driver"); +MODULE_ALIAS("platform:sev-guest"); |