From: Dan Williams <dan.j.williams@intel.com>
To: linux-coco@lists.linux.dev
Cc: Borislav Petkov <bp@alien8.de>,
Tom Lendacky <thomas.lendacky@amd.com>,
Dionna Glaze <dionnaglaze@google.com>,
Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>,
Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@linux.intel.com>,
Alexey Kardashevskiy <aik@amd.com>,
Tom Lendacky <thomas.lendacky@amd.com>,
peterz@infradead.org, dave.hansen@linux.intel.com,
x86@kernel.org
Subject: [PATCH v7 6/7] virt: sevguest: Add TSM_REPORTS support for SNP_GET_EXT_REPORT
Date: Thu, 19 Oct 2023 18:17:00 -0700 [thread overview]
Message-ID: <169776461997.1705513.12624327821043619904.stgit@dwillia2-xfh.jf.intel.com> (raw)
In-Reply-To: <169776458564.1705513.13069337506739791098.stgit@dwillia2-xfh.jf.intel.com>
The sevguest driver was a first mover in the confidential computing
space. As a first mover that afforded some leeway to build the driver
without concern for common infrastructure.
Now that sevguest is no longer a singleton [1] the common operation of
building and transmitting attestation report blobs can / should be made
common. In this model the so called "TSM-provider" implementations can
share a common envelope ABI even if the contents of that envelope remain
vendor-specific. When / if the industry agrees on an attestation record
format, that definition can also fit in the same ABI. In the meantime
the kernel's maintenance burden is reduced and collaboration on the
commons is increased.
Convert sevguest to use CONFIG_TSM_REPORTS to retrieve the data that
the SNP_GET_EXT_REPORT ioctl produces. An example flow follows for
retrieving the report blob via the TSM interface utility,
assuming no nonce and VMPL==2:
report=/sys/kernel/config/tsm/report/report0
mkdir $report
echo 2 > $report/privlevel
dd if=/dev/urandom bs=64 count=1 > $report/inblob
hexdump -C $report/outblob # SNP report
hexdump -C $report/auxblob # cert_table
rmdir $report
Given that the platform implementation is free to return empty
certificate data if none is available it lets configfs-tsm be simplified
as it only needs to worry about wrapping SNP_GET_EXT_REPORT, and leave
SNP_GET_REPORT alone.
The old ioctls can be lazily deprecated, the main motivation of this
effort is to stop the proliferation of new ioctls, and to increase
cross-vendor collaboration.
Link: http://lore.kernel.org/r/64961c3baf8ce_142af829436@dwillia2-xfh.jf.intel.com.notmuch [1]
Cc: Borislav Petkov <bp@alien8.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Dionna Glaze <dionnaglaze@google.com>
Cc: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Tested-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Tested-by: Alexey Kardashevskiy <aik@amd.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
drivers/virt/coco/sev-guest/Kconfig | 1
drivers/virt/coco/sev-guest/sev-guest.c | 135 +++++++++++++++++++++++++++++++
include/uapi/linux/psp-sev.h | 1
include/uapi/linux/sev-guest.h | 4 +
4 files changed, 140 insertions(+), 1 deletion(-)
diff --git a/drivers/virt/coco/sev-guest/Kconfig b/drivers/virt/coco/sev-guest/Kconfig
index da2d7ca531f0..1cffc72c41cb 100644
--- a/drivers/virt/coco/sev-guest/Kconfig
+++ b/drivers/virt/coco/sev-guest/Kconfig
@@ -5,6 +5,7 @@ config SEV_GUEST
select CRYPTO
select CRYPTO_AEAD2
select CRYPTO_GCM
+ select TSM_REPORTS
help
SEV-SNP firmware provides the guest a mechanism to communicate with
the PSP without risk from a malicious hypervisor who wishes to read,
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index e5f8f115f4af..bc564adcf499 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -16,10 +16,13 @@
#include <linux/miscdevice.h>
#include <linux/set_memory.h>
#include <linux/fs.h>
+#include <linux/tsm.h>
#include <crypto/aead.h>
#include <linux/scatterlist.h>
#include <linux/psp-sev.h>
#include <linux/sockptr.h>
+#include <linux/cleanup.h>
+#include <linux/uuid.h>
#include <uapi/linux/sev-guest.h>
#include <uapi/linux/psp-sev.h>
@@ -768,6 +771,130 @@ static u8 *get_vmpck(int id, struct snp_secrets_page_layout *layout, u32 **seqno
return key;
}
+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_report_new(struct tsm_report *report, void *data)
+{
+ struct snp_msg_cert_entry *cert_table;
+ struct tsm_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;
+
+ void *buf __free(kvfree) = kvzalloc(size, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ guard(mutex)(&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");
+ return -ENOTTY;
+ }
+
+ 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 const struct tsm_ops sev_tsm_ops = {
+ .name = KBUILD_MODNAME,
+ .report_new = sev_report_new,
+};
+
+static void unregister_sev_tsm(void *data)
+{
+ tsm_unregister(&sev_tsm_ops);
+}
+
static int __init sev_guest_probe(struct platform_device *pdev)
{
struct snp_secrets_page_layout *layout;
@@ -841,6 +968,14 @@ static int __init sev_guest_probe(struct platform_device *pdev)
snp_dev->input.resp_gpa = __pa(snp_dev->response);
snp_dev->input.data_gpa = __pa(snp_dev->certs_data);
+ ret = tsm_register(&sev_tsm_ops, snp_dev, &tsm_report_extra_type);
+ if (ret)
+ goto e_free_cert_data;
+
+ ret = devm_add_action_or_reset(&pdev->dev, unregister_sev_tsm, NULL);
+ if (ret)
+ goto e_free_cert_data;
+
ret = misc_register(misc);
if (ret)
goto e_free_cert_data;
diff --git a/include/uapi/linux/psp-sev.h b/include/uapi/linux/psp-sev.h
index 1c9da485318f..b44ba7dcdefc 100644
--- a/include/uapi/linux/psp-sev.h
+++ b/include/uapi/linux/psp-sev.h
@@ -68,6 +68,7 @@ typedef enum {
SEV_RET_INVALID_PARAM,
SEV_RET_RESOURCE_LIMIT,
SEV_RET_SECURE_DATA_INVALID,
+ SEV_RET_INVALID_KEY = 0x27,
SEV_RET_MAX,
} sev_ret_code;
diff --git a/include/uapi/linux/sev-guest.h b/include/uapi/linux/sev-guest.h
index 2aa39112cf8d..154a87a1eca9 100644
--- a/include/uapi/linux/sev-guest.h
+++ b/include/uapi/linux/sev-guest.h
@@ -14,9 +14,11 @@
#include <linux/types.h>
+#define SNP_REPORT_USER_DATA_SIZE 64
+
struct snp_report_req {
/* user data that should be included in the report */
- __u8 user_data[64];
+ __u8 user_data[SNP_REPORT_USER_DATA_SIZE];
/* The vmpl level to be included in the report */
__u32 vmpl;
next prev parent reply other threads:[~2023-10-20 1:17 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-20 1:16 [PATCH v7 0/7] configfs-tsm: Attestation Report ABI Dan Williams
2023-10-20 1:16 ` [PATCH v7 1/7] virt: sevguest: Fix passing a stack buffer as a scatterlist target Dan Williams
2023-10-20 1:16 ` [PATCH v7 2/7] virt: coco: Add a coco/Makefile and coco/Kconfig Dan Williams
2023-10-20 1:16 ` [PATCH v7 3/7] configfs-tsm: Introduce a shared ABI for attestation reports Dan Williams
2023-10-25 4:14 ` Qinkun Bao
2023-10-25 20:06 ` Dan Williams
2023-10-27 1:30 ` Chong Cai
2023-10-20 1:16 ` [PATCH v7 4/7] virt: sevguest: Prep for kernel internal get_ext_report() Dan Williams
2023-10-20 1:16 ` [PATCH v7 5/7] mm/slab: Add __free() support for kvfree Dan Williams
2023-10-20 1:17 ` Dan Williams [this message]
2023-10-20 3:25 ` [PATCH v7 6/7] virt: sevguest: Add TSM_REPORTS support for SNP_GET_EXT_REPORT Alexey Kardashevskiy
2023-10-20 1:17 ` [PATCH v7 7/7] virt: tdx-guest: Add Quote generation support using TSM_REPORTS Dan Williams
2023-10-24 17:08 ` Dan Williams
2023-12-21 1:50 ` Xiaoyao Li
2024-01-08 2:55 ` Kuppuswamy Sathyanarayanan
2024-01-09 2:13 ` Xiaoyao Li
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=169776461997.1705513.12624327821043619904.stgit@dwillia2-xfh.jf.intel.com \
--to=dan.j.williams@intel.com \
--cc=aik@amd.com \
--cc=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=dionnaglaze@google.com \
--cc=jpiotrowski@linux.microsoft.com \
--cc=linux-coco@lists.linux.dev \
--cc=peterz@infradead.org \
--cc=sathyanarayanan.kuppuswamy@linux.intel.com \
--cc=thomas.lendacky@amd.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.