From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 77839C433EF for ; Tue, 1 Feb 2022 20:33:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239455AbiBAUdj (ORCPT ); Tue, 1 Feb 2022 15:33:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53882 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238807AbiBAUd1 (ORCPT ); Tue, 1 Feb 2022 15:33:27 -0500 Received: from mail-lf1-x12a.google.com (mail-lf1-x12a.google.com [IPv6:2a00:1450:4864:20::12a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 999F7C06173D for ; Tue, 1 Feb 2022 12:33:26 -0800 (PST) Received: by mail-lf1-x12a.google.com with SMTP id o12so36245488lfg.12 for ; Tue, 01 Feb 2022 12:33:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=3vFKytq2CuTSlrmUntYNdQNU4NhqwMxbQ1d5TU8TF1s=; b=YMg4ZVS55tBLdTBWzrQ+SyoEJ2i+XcFVNhI3f/F3keEpHw7roVNpNLsgUADOV/J7Df 9XKhgW5C5lEHVyMacM4zzkckOlSHF7ditHU2YlH85nNmdjPpEH8UQCNjCprgH8ggiQ1F Y/HVBo2OnUJA1QWPxFd65ikX4jeVD4WItNU9120rQ35wMaYIE8mu5Tqi5g4L2jZJhp7a ftEVGrjBX9qSUQYHxJeVJeZ+Y6ZIrNnX/ND9m1errj2TGRfANL9PMB5fi4QGea3/RWui PAOy7sjoMT8zv6tZFGzAYjpmwojCTjNrOTLk4N4TOzys+Wmab6CefwABiQtwtidRpa0T NGXQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=3vFKytq2CuTSlrmUntYNdQNU4NhqwMxbQ1d5TU8TF1s=; b=B4my7cYIx84MPWQolebTkHghakMjk5f5DfAJ6dKjto5TmRqrBeMmR/C/zWAAfWDgoU 9gEK2QLwh/bFPIYbD4JsQs8m+UCD5P0HcBRZG57oPbT6sKAhLYC1XIXfzIoRyVw8LUnH rO1wNe5uyLl/WHeE0Zur20Ha+s7/2X9LOOJ+NvZA9Qar+OFpwPxqlZ7TiMl9RLYnmb2q 0Fi9PRaa7an8fZt6NAodR2+SrLldgAK5WGu9bLgy3XGj9vEscAN1Fy3bwtGcJ7/kAkuP 0CiM24GxuPQ4IVaHNdqJEwXluH5zpKHb6wGtStxUTvVS/at4s3ClDGPvBx0Iey78dURC PUkw== X-Gm-Message-State: AOAM533Qg+bbEXBIvYJfl6cKtGqXMU6SZE5CZZxJxMKew3bFOyMNgw+x pcCETKXzThZMp/5iA5rhr2Wfbb7//kbb//tMXrIYrg== X-Google-Smtp-Source: ABdhPJwMhdFfsRTfnRYT3B4NYPyV1JOkJ3NzQUetI3xWMmYjxT6SyI2UY0VUB2fsmjMO9etlifa4Gbd0nKOaGsqBGPk= X-Received: by 2002:a19:9219:: with SMTP id u25mr20412893lfd.685.1643747604421; Tue, 01 Feb 2022 12:33:24 -0800 (PST) MIME-Version: 1.0 References: <20220128171804.569796-1-brijesh.singh@amd.com> <20220128171804.569796-42-brijesh.singh@amd.com> In-Reply-To: <20220128171804.569796-42-brijesh.singh@amd.com> From: Peter Gonda Date: Tue, 1 Feb 2022 13:33:12 -0700 Message-ID: Subject: Re: [PATCH v9 41/43] virt: Add SEV-SNP guest driver To: Brijesh Singh Cc: "the arch/x86 maintainers" , LKML , kvm list , linux-efi@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, Thomas Gleixner , Ingo Molnar , Joerg Roedel , Tom Lendacky , "H. Peter Anvin" , Ard Biesheuvel , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Jim Mattson , Andy Lutomirski , Dave Hansen , Sergio Lopez , Peter Zijlstra , Srinivas Pandruvada , David Rientjes , Dov Murik , Tobin Feldman-Fitzthum , Borislav Petkov , Michael Roth , Vlastimil Babka , "Kirill A . Shutemov" , Andi Kleen , "Dr . David Alan Gilbert" , brijesh.ksingh@gmail.com, Tony Luck , Marc Orr , Sathyanarayanan Kuppuswamy Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 28, 2022 at 10:19 AM Brijesh Singh wrote: > > SEV-SNP specification provides the guest a mechanism to communicate with > the PSP without risk from a malicious hypervisor who wishes to read, alter, > drop or replay the messages sent. The driver uses snp_issue_guest_request() > to issue GHCB SNP_GUEST_REQUEST or SNP_EXT_GUEST_REQUEST NAE events to > submit the request to PSP. > > The PSP requires that all communication should be encrypted using key > specified through the platform_data. > > The userspace can use SNP_GET_REPORT ioctl() to query the guest > attestation report. > > See SEV-SNP spec section Guest Messages for more details. > > Signed-off-by: Brijesh Singh Reviewed-by: Peter Gonda I'll try and do some basic functionality testing done with this later. > --- > Documentation/virt/coco/sevguest.rst | 81 ++++ > drivers/virt/Kconfig | 3 + > drivers/virt/Makefile | 1 + > drivers/virt/coco/sevguest/Kconfig | 12 + > drivers/virt/coco/sevguest/Makefile | 2 + > drivers/virt/coco/sevguest/sevguest.c | 605 ++++++++++++++++++++++++++ > drivers/virt/coco/sevguest/sevguest.h | 98 +++++ > include/uapi/linux/sev-guest.h | 50 +++ > 8 files changed, 852 insertions(+) > create mode 100644 Documentation/virt/coco/sevguest.rst > create mode 100644 drivers/virt/coco/sevguest/Kconfig > create mode 100644 drivers/virt/coco/sevguest/Makefile > create mode 100644 drivers/virt/coco/sevguest/sevguest.c > create mode 100644 drivers/virt/coco/sevguest/sevguest.h > create mode 100644 include/uapi/linux/sev-guest.h > > diff --git a/Documentation/virt/coco/sevguest.rst b/Documentation/virt/coco/sevguest.rst > new file mode 100644 > index 000000000000..47ef3b0821d5 > --- /dev/null > +++ b/Documentation/virt/coco/sevguest.rst > @@ -0,0 +1,81 @@ > +.. SPDX-License-Identifier: GPL-2.0 > + > +=================================================================== > +The Definitive SEV Guest API Documentation > +=================================================================== > + > +1. General description > +====================== > + > +The SEV API is a set of ioctls that are used by the guest or hypervisor > +to get or set certain aspect of the SEV virtual machine. The ioctls belong > +to the following classes: > + > + - Hypervisor ioctls: These query and set global attributes which affect the > + whole SEV firmware. These ioctl are used by platform provision tools. > + > + - Guest ioctls: These query and set attributes of the SEV virtual machine. > + > +2. API description > +================== > + > +This section describes ioctls that can be used to query or set SEV guests. > +For each ioctl, the following information is provided along with a > +description: > + > + Technology: > + which SEV technology provides this ioctl. sev, sev-es, sev-snp or all. > + > + Type: > + hypervisor or guest. The ioctl can be used inside the guest or the > + hypervisor. > + > + Parameters: > + what parameters are accepted by the ioctl. > + > + Returns: > + the return value. General error numbers (ENOMEM, EINVAL) > + are not detailed, but errors with specific meanings are. > + > +The guest ioctl should be issued on a file descriptor of the /dev/sev-guest device. > +The ioctl accepts struct snp_user_guest_request. The input and output structure is > +specified through the req_data and resp_data field respectively. If the ioctl fails > +to execute due to a firmware error, then fw_err code will be set otherwise the > +fw_err will be set to 0xff. > + > +:: > + struct snp_guest_request_ioctl { > + /* Message version number */ > + __u32 msg_version; > + > + /* Request and response structure address */ > + __u64 req_data; > + __u64 resp_data; > + > + /* firmware error code on failure (see psp-sev.h) */ > + __u64 fw_err; > + }; > + > +2.1 SNP_GET_REPORT > +------------------ > + > +:Technology: sev-snp > +:Type: guest ioctl > +:Parameters (in): struct snp_report_req > +:Returns (out): struct snp_report_resp on success, -negative on error > + > +The SNP_GET_REPORT ioctl can be used to query the attestation report from the > +SEV-SNP firmware. The ioctl uses the SNP_GUEST_REQUEST (MSG_REPORT_REQ) command > +provided by the SEV-SNP firmware to query the attestation report. > + > +On success, the snp_report_resp.data will contains the report. The report > +contain the format described in the SEV-SNP specification. See the SEV-SNP > +specification for further details. > + > + > +Reference > +--------- > + > +SEV-SNP and GHCB specification: developer.amd.com/sev > + > +The driver is based on SEV-SNP firmware spec 0.9 and GHCB spec version 2.0. > diff --git a/drivers/virt/Kconfig b/drivers/virt/Kconfig > index 8061e8ef449f..e457e47610d3 100644 > --- a/drivers/virt/Kconfig > +++ b/drivers/virt/Kconfig > @@ -36,4 +36,7 @@ source "drivers/virt/vboxguest/Kconfig" > source "drivers/virt/nitro_enclaves/Kconfig" > > source "drivers/virt/acrn/Kconfig" > + > +source "drivers/virt/coco/sevguest/Kconfig" > + > endif > diff --git a/drivers/virt/Makefile b/drivers/virt/Makefile > index 3e272ea60cd9..9c704a6fdcda 100644 > --- a/drivers/virt/Makefile > +++ b/drivers/virt/Makefile > @@ -8,3 +8,4 @@ obj-y += vboxguest/ > > obj-$(CONFIG_NITRO_ENCLAVES) += nitro_enclaves/ > obj-$(CONFIG_ACRN_HSM) += acrn/ > +obj-$(CONFIG_SEV_GUEST) += coco/sevguest/ > diff --git a/drivers/virt/coco/sevguest/Kconfig b/drivers/virt/coco/sevguest/Kconfig > new file mode 100644 > index 000000000000..07ab9ec6471c > --- /dev/null > +++ b/drivers/virt/coco/sevguest/Kconfig > @@ -0,0 +1,12 @@ > +config SEV_GUEST > + tristate "AMD SEV Guest driver" > + default y > + depends on AMD_MEM_ENCRYPT && CRYPTO_AEAD2 > + help > + SEV-SNP firmware provides the guest a mechanism to communicate with > + the PSP without risk from a malicious hypervisor who wishes to read, > + alter, drop or replay the messages sent. The driver provides > + userspace interface to communicate with the PSP to request the > + attestation report and more. > + > + If you choose 'M' here, this module will be called sevguest. > diff --git a/drivers/virt/coco/sevguest/Makefile b/drivers/virt/coco/sevguest/Makefile > new file mode 100644 > index 000000000000..b1ffb2b4177b > --- /dev/null > +++ b/drivers/virt/coco/sevguest/Makefile > @@ -0,0 +1,2 @@ > +# SPDX-License-Identifier: GPL-2.0-only > +obj-$(CONFIG_SEV_GUEST) += sevguest.o > diff --git a/drivers/virt/coco/sevguest/sevguest.c b/drivers/virt/coco/sevguest/sevguest.c > new file mode 100644 > index 000000000000..6dc0785ddd4b > --- /dev/null > +++ b/drivers/virt/coco/sevguest/sevguest.c > @@ -0,0 +1,605 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * AMD Secure Encrypted Virtualization Nested Paging (SEV-SNP) guest request interface > + * > + * Copyright (C) 2021 Advanced Micro Devices, Inc. > + * > + * Author: Brijesh Singh > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#include > +#include > + > +#include "sevguest.h" > + > +#define DEVICE_NAME "sev-guest" > +#define AAD_LEN 48 > +#define MSG_HDR_VER 1 > + > +struct snp_guest_crypto { > + struct crypto_aead *tfm; > + u8 *iv, *authtag; > + int iv_len, a_len; > +}; > + > +struct snp_guest_dev { > + struct device *dev; > + struct miscdevice misc; > + > + struct snp_guest_crypto *crypto; > + struct snp_guest_msg *request, *response; > + struct snp_secrets_page_layout *layout; > + struct snp_req_data input; > + u32 *os_area_msg_seqno; > + u8 *vmpck; > +}; > + > +static u32 vmpck_id; > +module_param(vmpck_id, uint, 0444); > +MODULE_PARM_DESC(vmpck_id, "The VMPCK ID to use when communicating with the PSP."); > + > +static DEFINE_MUTEX(snp_cmd_mutex); > + > +static bool is_vmpck_empty(struct snp_guest_dev *snp_dev) > +{ > + char zero_key[VMPCK_KEY_LEN] = {0}; > + > + if (snp_dev->vmpck) > + return memcmp(snp_dev->vmpck, zero_key, VMPCK_KEY_LEN) == 0; > + > + return true; > +} > + > +static void snp_disable_vmpck(struct snp_guest_dev *snp_dev) > +{ > + memzero_explicit(snp_dev->vmpck, VMPCK_KEY_LEN); > + snp_dev->vmpck = NULL; > +} > + > +static inline u64 __snp_get_msg_seqno(struct snp_guest_dev *snp_dev) > +{ > + u64 count; > + > + lockdep_assert_held(&snp_cmd_mutex); > + > + /* Read the current message sequence counter from secrets pages */ > + count = *snp_dev->os_area_msg_seqno; > + > + return count + 1; > +} > + > +/* Return a non-zero on success */ > +static u64 snp_get_msg_seqno(struct snp_guest_dev *snp_dev) > +{ > + u64 count = __snp_get_msg_seqno(snp_dev); > + > + /* > + * The message sequence counter for the SNP guest request is a 64-bit > + * value but the version 2 of GHCB specification defines a 32-bit storage > + * for it. If the counter exceeds the 32-bit value then return zero. > + * The caller should check the return value, but if the caller happens to > + * not check the value and use it, then the firmware treats zero as an > + * invalid number and will fail the message request. > + */ > + if (count >= UINT_MAX) { > + pr_err_ratelimited("SNP guest request message sequence counter overflow\n"); > + return 0; > + } > + > + return count; > +} > + > +static void snp_inc_msg_seqno(struct snp_guest_dev *snp_dev) > +{ > + /* > + * The counter is also incremented by the PSP, so increment it by 2 > + * and save in secrets page. > + */ > + *snp_dev->os_area_msg_seqno += 2; > +} > + > +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); > +} > + > +static struct snp_guest_crypto *init_crypto(struct snp_guest_dev *snp_dev, u8 *key, size_t keylen) > +{ > + struct snp_guest_crypto *crypto; > + > + crypto = kzalloc(sizeof(*crypto), GFP_KERNEL_ACCOUNT); > + if (!crypto) > + return NULL; > + > + crypto->tfm = crypto_alloc_aead("gcm(aes)", 0, 0); > + if (IS_ERR(crypto->tfm)) > + goto e_free; > + > + if (crypto_aead_setkey(crypto->tfm, key, keylen)) > + goto e_free_crypto; > + > + crypto->iv_len = crypto_aead_ivsize(crypto->tfm); > + if (crypto->iv_len < 12) { > + dev_err(snp_dev->dev, "IV length is less than 12.\n"); > + goto e_free_crypto; > + } > + > + crypto->iv = kmalloc(crypto->iv_len, GFP_KERNEL_ACCOUNT); > + if (!crypto->iv) > + goto e_free_crypto; > + > + if (crypto_aead_authsize(crypto->tfm) > MAX_AUTHTAG_LEN) { > + if (crypto_aead_setauthsize(crypto->tfm, MAX_AUTHTAG_LEN)) { > + dev_err(snp_dev->dev, "failed to set authsize to %d\n", MAX_AUTHTAG_LEN); > + goto e_free_crypto; > + } > + } > + > + crypto->a_len = crypto_aead_authsize(crypto->tfm); > + crypto->authtag = kmalloc(crypto->a_len, GFP_KERNEL_ACCOUNT); > + if (!crypto->authtag) > + goto e_free_crypto; > + > + return crypto; > + > +e_free_crypto: > + crypto_free_aead(crypto->tfm); > +e_free: > + kfree(crypto->iv); > + kfree(crypto->authtag); > + kfree(crypto); > + > + return NULL; > +} > + > +static void deinit_crypto(struct snp_guest_crypto *crypto) > +{ > + crypto_free_aead(crypto->tfm); > + kfree(crypto->iv); > + kfree(crypto->authtag); > + kfree(crypto); > +} > + > +static int enc_dec_message(struct snp_guest_crypto *crypto, struct snp_guest_msg *msg, > + u8 *src_buf, u8 *dst_buf, size_t len, bool enc) > +{ > + struct snp_guest_msg_hdr *hdr = &msg->hdr; > + struct scatterlist src[3], dst[3]; > + DECLARE_CRYPTO_WAIT(wait); > + struct aead_request *req; > + int ret; > + > + req = aead_request_alloc(crypto->tfm, GFP_KERNEL); > + if (!req) > + return -ENOMEM; > + > + /* > + * AEAD memory operations: > + * +------ AAD -------+------- DATA -----+---- AUTHTAG----+ > + * | msg header | plaintext | hdr->authtag | > + * | bytes 30h - 5Fh | or | | > + * | | cipher | | > + * +------------------+------------------+----------------+ > + */ > + sg_init_table(src, 3); > + sg_set_buf(&src[0], &hdr->algo, AAD_LEN); > + sg_set_buf(&src[1], src_buf, hdr->msg_sz); > + sg_set_buf(&src[2], hdr->authtag, crypto->a_len); > + > + sg_init_table(dst, 3); > + sg_set_buf(&dst[0], &hdr->algo, AAD_LEN); > + sg_set_buf(&dst[1], dst_buf, hdr->msg_sz); > + sg_set_buf(&dst[2], hdr->authtag, crypto->a_len); > + > + aead_request_set_ad(req, AAD_LEN); > + aead_request_set_tfm(req, crypto->tfm); > + aead_request_set_callback(req, 0, crypto_req_done, &wait); > + > + aead_request_set_crypt(req, src, dst, len, crypto->iv); > + ret = crypto_wait_req(enc ? crypto_aead_encrypt(req) : crypto_aead_decrypt(req), &wait); > + > + aead_request_free(req); > + return ret; > +} > + > +static int __enc_payload(struct snp_guest_dev *snp_dev, struct snp_guest_msg *msg, > + void *plaintext, size_t len) > +{ > + struct snp_guest_crypto *crypto = snp_dev->crypto; > + struct snp_guest_msg_hdr *hdr = &msg->hdr; > + > + memset(crypto->iv, 0, crypto->iv_len); > + memcpy(crypto->iv, &hdr->msg_seqno, sizeof(hdr->msg_seqno)); > + > + return enc_dec_message(crypto, msg, plaintext, msg->payload, len, true); > +} > + > +static int dec_payload(struct snp_guest_dev *snp_dev, struct snp_guest_msg *msg, > + void *plaintext, size_t len) > +{ > + struct snp_guest_crypto *crypto = snp_dev->crypto; > + struct snp_guest_msg_hdr *hdr = &msg->hdr; > + > + /* Build IV with response buffer sequence number */ > + memset(crypto->iv, 0, crypto->iv_len); > + memcpy(crypto->iv, &hdr->msg_seqno, sizeof(hdr->msg_seqno)); > + > + return enc_dec_message(crypto, msg, msg->payload, plaintext, len, false); > +} > + > +static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, void *payload, u32 sz) > +{ > + struct snp_guest_crypto *crypto = snp_dev->crypto; > + struct snp_guest_msg *resp = snp_dev->response; > + struct snp_guest_msg *req = snp_dev->request; > + struct snp_guest_msg_hdr *req_hdr = &req->hdr; > + struct snp_guest_msg_hdr *resp_hdr = &resp->hdr; > + > + dev_dbg(snp_dev->dev, "response [seqno %lld type %d version %d sz %d]\n", > + resp_hdr->msg_seqno, resp_hdr->msg_type, resp_hdr->msg_version, resp_hdr->msg_sz); > + > + /* Verify that the sequence counter is incremented by 1 */ > + if (unlikely(resp_hdr->msg_seqno != (req_hdr->msg_seqno + 1))) > + return -EBADMSG; > + > + /* Verify response message type and version number. */ > + if (resp_hdr->msg_type != (req_hdr->msg_type + 1) || > + resp_hdr->msg_version != req_hdr->msg_version) > + return -EBADMSG; > + > + /* > + * If the message size is greater than our buffer length then return > + * an error. > + */ > + if (unlikely((resp_hdr->msg_sz + crypto->a_len) > sz)) > + return -EBADMSG; > + > + /* Decrypt the payload */ > + return dec_payload(snp_dev, resp, payload, resp_hdr->msg_sz + crypto->a_len); > +} > + > +static bool enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8 type, > + void *payload, size_t sz) > +{ > + struct snp_guest_msg *req = snp_dev->request; > + struct snp_guest_msg_hdr *hdr = &req->hdr; > + > + memset(req, 0, sizeof(*req)); > + > + hdr->algo = SNP_AEAD_AES_256_GCM; > + hdr->hdr_version = MSG_HDR_VER; > + hdr->hdr_sz = sizeof(*hdr); > + hdr->msg_type = type; > + hdr->msg_version = version; > + hdr->msg_seqno = seqno; > + hdr->msg_vmpck = vmpck_id; > + hdr->msg_sz = sz; > + > + /* Verify the sequence number is non-zero */ > + if (!hdr->msg_seqno) > + return -ENOSR; > + > + dev_dbg(snp_dev->dev, "request [seqno %lld type %d version %d sz %d]\n", > + hdr->msg_seqno, hdr->msg_type, hdr->msg_version, hdr->msg_sz); > + > + return __enc_payload(snp_dev, req, payload, sz); > +} > + > +static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, int msg_ver, > + u8 type, void *req_buf, size_t req_sz, void *resp_buf, > + u32 resp_sz, __u64 *fw_err) > +{ > + unsigned long err; > + u64 seqno; > + int rc; > + > + /* Get message sequence and verify that its a non-zero */ > + seqno = snp_get_msg_seqno(snp_dev); > + if (!seqno) > + return -EIO; > + > + memset(snp_dev->response, 0, sizeof(*snp_dev->response)); > + > + /* Encrypt the userspace provided payload */ > + rc = enc_payload(snp_dev, seqno, msg_ver, type, req_buf, req_sz); > + if (rc) > + return rc; > + > + /* Call firmware to process the request */ > + rc = snp_issue_guest_request(exit_code, &snp_dev->input, &err); > + if (fw_err) > + *fw_err = err; All the other pointers are required. Why not require this one to make it simpler? > + > + if (rc) > + return rc; > + > + rc = verify_and_dec_payload(snp_dev, resp_buf, resp_sz); > + if (rc) { > + /* > + * 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. > + */ > + dev_alert(snp_dev->dev, > + "Detected unexpected decode failure, disabling the vmpck_id %d\n", > + vmpck_id); > + snp_disable_vmpck(snp_dev); > + return rc; > + } > + > + /* Increment to new message sequence after payload decryption was successful. */ > + snp_inc_msg_seqno(snp_dev); > + > + return 0; > +} > + > +static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg) > +{ > + struct snp_guest_crypto *crypto = snp_dev->crypto; > + struct snp_report_req req = {0}; > + struct snp_report_resp *resp; > + int rc, resp_len; > + > + if (!arg->req_data || !arg->resp_data) > + return -EINVAL; > + > + /* Copy the request payload from userspace */ > + if (copy_from_user(&req, (void __user *)arg->req_data, sizeof(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(resp->data) + crypto->a_len; > + resp = kzalloc(resp_len, GFP_KERNEL_ACCOUNT); > + if (!resp) > + return -ENOMEM; > + > + /* Issue the command to get the attestation report */ > + rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg->msg_version, > + SNP_MSG_REPORT_REQ, &req, sizeof(req), resp->data, > + resp_len, &arg->fw_err); > + if (rc) > + goto e_free; > + > + /* Copy the response payload to userspace */ > + if (copy_to_user((void __user *)arg->resp_data, resp, sizeof(*resp))) > + rc = -EFAULT; > + > +e_free: > + kfree(resp); > + return rc; > +} > + > +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; > + int ret = -ENOTTY; > + > + if (copy_from_user(&input, argp, sizeof(input))) > + return -EFAULT; > + > + input.fw_err = 0xff; > + > + /* Message version must be non-zero */ > + if (!input.msg_version) > + return -EINVAL; > + > + mutex_lock(&snp_cmd_mutex); > + > + /* Check if the VMPCK is not empty */ > + if (is_vmpck_empty(snp_dev)) { > + dev_err_ratelimited(snp_dev->dev, "VMPCK is disabled\n"); > + mutex_unlock(&snp_cmd_mutex); > + return -ENOTTY; > + } > + > + switch (ioctl) { > + case SNP_GET_REPORT: > + ret = get_report(snp_dev, &input); > + break; > + default: > + break; > + } > + > + mutex_unlock(&snp_cmd_mutex); > + > + if (input.fw_err && copy_to_user(argp, &input, sizeof(input))) > + return -EFAULT; > + > + return ret; > +} > + > +static void free_shared_pages(void *buf, size_t sz) > +{ > + unsigned int npages = PAGE_ALIGN(sz) >> PAGE_SHIFT; > + > + if (!buf) > + return; > + > + /* If fail to restore the encryption mask then leak it. */ > + if (WARN_ONCE(set_memory_encrypted((unsigned long)buf, npages), > + "Failed to restore encryption mask (leak it)\n")) > + return; > + > + __free_pages(virt_to_page(buf), get_order(sz)); > +} > + > +static void *alloc_shared_pages(size_t sz) > +{ > + unsigned int npages = PAGE_ALIGN(sz) >> PAGE_SHIFT; > + struct page *page; > + int ret; > + > + page = alloc_pages(GFP_KERNEL_ACCOUNT, get_order(sz)); > + if (IS_ERR(page)) > + return NULL; > + > + ret = set_memory_decrypted((unsigned long)page_address(page), npages); > + if (ret) { > + pr_err("SEV-SNP: failed to mark page shared, ret=%d\n", ret); > + __free_pages(page, get_order(sz)); > + return NULL; > + } > + > + return page_address(page); > +} > + > +static const struct file_operations snp_guest_fops = { > + .owner = THIS_MODULE, > + .unlocked_ioctl = snp_guest_ioctl, > +}; > + > +static u8 *get_vmpck(int id, struct snp_secrets_page_layout *layout, u32 **seqno) > +{ > + u8 *key = NULL; > + > + switch (id) { > + case 0: > + *seqno = &layout->os_area.msg_seqno_0; > + key = layout->vmpck0; > + break; > + case 1: > + *seqno = &layout->os_area.msg_seqno_1; > + key = layout->vmpck1; > + break; > + case 2: > + *seqno = &layout->os_area.msg_seqno_2; > + key = layout->vmpck2; > + break; > + case 3: > + *seqno = &layout->os_area.msg_seqno_3; > + key = layout->vmpck3; > + break; > + default: > + break; > + } > + > + return key; > +} > + > +static int __init snp_guest_probe(struct platform_device *pdev) > +{ > + struct snp_secrets_page_layout *layout; > + struct snp_guest_platform_data *data; > + struct device *dev = &pdev->dev; > + struct snp_guest_dev *snp_dev; > + struct miscdevice *misc; > + int ret; > + > + if (!dev->platform_data) > + return -ENODEV; > + > + data = (struct snp_guest_platform_data *)dev->platform_data; > + layout = (__force void *)ioremap_encrypted(data->secrets_gpa, PAGE_SIZE); > + if (!layout) > + return -ENODEV; > + > + ret = -ENOMEM; > + snp_dev = devm_kzalloc(&pdev->dev, sizeof(struct snp_guest_dev), GFP_KERNEL); > + if (!snp_dev) > + goto e_fail; > + > + ret = -EINVAL; > + snp_dev->vmpck = get_vmpck(vmpck_id, layout, &snp_dev->os_area_msg_seqno); > + if (!snp_dev->vmpck) { > + dev_err(dev, "invalid vmpck id %d\n", vmpck_id); > + goto e_fail; > + } > + > + /* Verify that VMPCK is not zero. */ > + if (is_vmpck_empty(snp_dev)) { > + dev_err(dev, "vmpck id %d is null\n", vmpck_id); > + goto e_fail; > + } > + > + platform_set_drvdata(pdev, snp_dev); > + snp_dev->dev = dev; > + snp_dev->layout = layout; > + > + /* Allocate the shared page used for the request and response message. */ > + snp_dev->request = alloc_shared_pages(sizeof(struct snp_guest_msg)); > + if (!snp_dev->request) > + goto e_fail; > + > + snp_dev->response = alloc_shared_pages(sizeof(struct snp_guest_msg)); > + if (!snp_dev->response) > + goto e_fail; > + > + ret = -EIO; > + snp_dev->crypto = init_crypto(snp_dev, snp_dev->vmpck, VMPCK_KEY_LEN); > + if (!snp_dev->crypto) > + goto e_fail; > + > + misc = &snp_dev->misc; > + misc->minor = MISC_DYNAMIC_MINOR; > + misc->name = DEVICE_NAME; > + misc->fops = &snp_guest_fops; > + > + /* initial the input address for guest request */ > + snp_dev->input.req_gpa = __pa(snp_dev->request); > + snp_dev->input.resp_gpa = __pa(snp_dev->response); > + > + ret = misc_register(misc); > + if (ret) > + goto e_fail; > + > + dev_info(dev, "Initialized SEV-SNP guest driver (using vmpck_id %d)\n", vmpck_id); > + return 0; > + > +e_fail: > + iounmap(layout); > + free_shared_pages(snp_dev->request, sizeof(struct snp_guest_msg)); > + free_shared_pages(snp_dev->response, sizeof(struct snp_guest_msg)); > + > + return ret; > +} > + > +static int __exit snp_guest_remove(struct platform_device *pdev) > +{ > + struct snp_guest_dev *snp_dev = platform_get_drvdata(pdev); > + > + free_shared_pages(snp_dev->request, sizeof(struct snp_guest_msg)); > + free_shared_pages(snp_dev->response, sizeof(struct snp_guest_msg)); > + deinit_crypto(snp_dev->crypto); > + misc_deregister(&snp_dev->misc); > + > + return 0; > +} > + > +static struct platform_driver snp_guest_driver = { > + .remove = __exit_p(snp_guest_remove), > + .driver = { > + .name = "snp-guest", > + }, > +}; > + > +module_platform_driver_probe(snp_guest_driver, snp_guest_probe); > + > +MODULE_AUTHOR("Brijesh Singh "); > +MODULE_LICENSE("GPL"); > +MODULE_VERSION("1.0.0"); > +MODULE_DESCRIPTION("AMD SNP Guest Driver"); > diff --git a/drivers/virt/coco/sevguest/sevguest.h b/drivers/virt/coco/sevguest/sevguest.h > new file mode 100644 > index 000000000000..cfa76cf8a21a > --- /dev/null > +++ b/drivers/virt/coco/sevguest/sevguest.h > @@ -0,0 +1,98 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > +/* > + * Copyright (C) 2021 Advanced Micro Devices, Inc. > + * > + * Author: Brijesh Singh > + * > + * SEV-SNP API spec is available at https://developer.amd.com/sev > + */ > + > +#ifndef __LINUX_SEVGUEST_H_ > +#define __LINUX_SEVGUEST_H_ > + > +#include > + > +#define MAX_AUTHTAG_LEN 32 > + > +/* See SNP spec SNP_GUEST_REQUEST section for the structure */ > +enum msg_type { > + SNP_MSG_TYPE_INVALID = 0, > + SNP_MSG_CPUID_REQ, > + SNP_MSG_CPUID_RSP, > + SNP_MSG_KEY_REQ, > + SNP_MSG_KEY_RSP, > + SNP_MSG_REPORT_REQ, > + SNP_MSG_REPORT_RSP, > + SNP_MSG_EXPORT_REQ, > + SNP_MSG_EXPORT_RSP, > + SNP_MSG_IMPORT_REQ, > + SNP_MSG_IMPORT_RSP, > + SNP_MSG_ABSORB_REQ, > + SNP_MSG_ABSORB_RSP, > + SNP_MSG_VMRK_REQ, > + SNP_MSG_VMRK_RSP, > + > + SNP_MSG_TYPE_MAX > +}; > + > +enum aead_algo { > + SNP_AEAD_INVALID, > + SNP_AEAD_AES_256_GCM, > +}; > + > +struct snp_guest_msg_hdr { > + u8 authtag[MAX_AUTHTAG_LEN]; > + u64 msg_seqno; > + u8 rsvd1[8]; > + u8 algo; > + u8 hdr_version; > + u16 hdr_sz; > + u8 msg_type; > + u8 msg_version; > + u16 msg_sz; > + u32 rsvd2; > + u8 msg_vmpck; > + u8 rsvd3[35]; > +} __packed; > + > +struct snp_guest_msg { > + struct snp_guest_msg_hdr hdr; > + u8 payload[4000]; > +} __packed; > + > +/* > + * The secrets page contains 96-bytes of reserved field that can be used by > + * the guest OS. The guest OS uses the area to save the message sequence > + * number for each VMPCK. > + * > + * See the GHCB spec section Secret page layout for the format for this area. > + */ > +struct secrets_os_area { > + u32 msg_seqno_0; > + u32 msg_seqno_1; > + u32 msg_seqno_2; > + u32 msg_seqno_3; > + u64 ap_jump_table_pa; > + u8 rsvd[40]; > + u8 guest_usage[32]; > +} __packed; > + > +#define VMPCK_KEY_LEN 32 > + > +/* See the SNP spec version 0.9 for secrets page format */ > +struct snp_secrets_page_layout { > + u32 version; > + u32 imien : 1, > + rsvd1 : 31; > + u32 fms; > + u32 rsvd2; > + u8 gosvw[16]; > + u8 vmpck0[VMPCK_KEY_LEN]; > + u8 vmpck1[VMPCK_KEY_LEN]; > + u8 vmpck2[VMPCK_KEY_LEN]; > + u8 vmpck3[VMPCK_KEY_LEN]; > + struct secrets_os_area os_area; > + u8 rsvd3[3840]; > +} __packed; > + > +#endif /* __LINUX_SNP_GUEST_H__ */ > diff --git a/include/uapi/linux/sev-guest.h b/include/uapi/linux/sev-guest.h > new file mode 100644 > index 000000000000..081d314a6279 > --- /dev/null > +++ b/include/uapi/linux/sev-guest.h > @@ -0,0 +1,50 @@ > +/* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note */ > +/* > + * Userspace interface for AMD SEV and SEV-SNP guest driver. > + * > + * Copyright (C) 2021 Advanced Micro Devices, Inc. > + * > + * Author: Brijesh Singh > + * > + * SEV API specification is available at: https://developer.amd.com/sev/ > + */ > + > +#ifndef __UAPI_LINUX_SEV_GUEST_H_ > +#define __UAPI_LINUX_SEV_GUEST_H_ > + > +#include > + > +struct snp_report_req { > + /* user data that should be included in the report */ > + __u8 user_data[64]; > + > + /* The vmpl level to be included in the report */ > + __u32 vmpl; > + > + /* Must be zero filled */ > + __u8 rsvd[28]; > +}; > + > +struct snp_report_resp { > + /* response data, see SEV-SNP spec for the format */ > + __u8 data[4000]; > +}; > + > +struct snp_guest_request_ioctl { > + /* message version number (must be non-zero) */ > + __u8 msg_version; > + > + /* Request and response structure address */ > + __u64 req_data; > + __u64 resp_data; > + > + /* firmware error code on failure (see psp-sev.h) */ > + __u64 fw_err; > +}; > + > +#define SNP_GUEST_REQ_IOC_TYPE 'S' > + > +/* Get SNP attestation report */ > +#define SNP_GET_REPORT _IOWR(SNP_GUEST_REQ_IOC_TYPE, 0x0, struct snp_guest_request_ioctl) > + > +#endif /* __UAPI_LINUX_SEV_GUEST_H_ */ > -- > 2.25.1 >