From: Dov Murik <dovmurik@linux.ibm.com>
To: Brijesh Singh <brijesh.singh@amd.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org, linux-efi@vger.kernel.org,
platform-driver-x86@vger.kernel.org, linux-coco@lists.linux.dev,
linux-mm@kvack.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Joerg Roedel <jroedel@suse.de>,
Tom Lendacky <thomas.lendacky@amd.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Ard Biesheuvel <ardb@kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>,
Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Sergio Lopez <slp@redhat.com>, Peter Gonda <pgonda@google.com>,
Peter Zijlstra <peterz@infradead.org>,
Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
David Rientjes <rientjes@google.com>,
Tobin Feldman-Fitzthum <tobin@ibm.com>,
Borislav Petkov <bp@alien8.de>,
Michael Roth <michael.roth@amd.com>,
Vlastimil Babka <vbabka@suse.cz>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
Andi Kleen <ak@linux.intel.com>,
tony.luck@intel.com, marcorr@google.com,
sathyanarayanan.kuppuswamy@linux.intel.com,
Dov Murik <dovmurik@linux.ibm.com>
Subject: Re: [PATCH Part1 v5 37/38] virt: sevguest: Add support to derive key
Date: Tue, 31 Aug 2021 21:59:55 +0300 [thread overview]
Message-ID: <a6841be9-a2ca-8d92-3346-af8513b528fc@linux.ibm.com> (raw)
In-Reply-To: <20210820151933.22401-38-brijesh.singh@amd.com>
Hi Brijesh,
On 20/08/2021 18:19, Brijesh Singh wrote:
> The SNP_GET_DERIVED_KEY ioctl interface can be used by the SNP guest to
> ask the firmware to provide a key derived from a root key. The derived
> key may be used by the guest for any purposes it choose, such as a
> sealing key or communicating with the external entities.
>
> See SEV-SNP firmware spec for more information.
>
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> ---
> Documentation/virt/coco/sevguest.rst | 18 ++++++++++
> drivers/virt/coco/sevguest/sevguest.c | 48 +++++++++++++++++++++++++++
> include/uapi/linux/sev-guest.h | 24 ++++++++++++++
> 3 files changed, 90 insertions(+)
>
> diff --git a/Documentation/virt/coco/sevguest.rst b/Documentation/virt/coco/sevguest.rst
> index 52d5915037ef..25446670d816 100644
> --- a/Documentation/virt/coco/sevguest.rst
> +++ b/Documentation/virt/coco/sevguest.rst
> @@ -67,3 +67,21 @@ provided by the SEV-SNP firmware to query the attestation report.
> On success, the snp_report_resp.data will contains the report. The report
> format is described in the SEV-SNP specification. See the SEV-SNP specification
> for further details.
> +
> +2.2 SNP_GET_DERIVED_KEY
> +-----------------------
> +:Technology: sev-snp
> +:Type: guest ioctl
> +:Parameters (in): struct snp_derived_key_req
> +:Returns (out): struct snp_derived_key_req on success, -negative on error
> +
> +The SNP_GET_DERIVED_KEY ioctl can be used to get a key derive from a root key.
> +The derived key can be used by the guest for any purpose, such as sealing keys
> +or communicating with external entities.
> +
> +The ioctl uses the SNP_GUEST_REQUEST (MSG_KEY_REQ) command provided by the
> +SEV-SNP firmware to derive the key. See SEV-SNP specification for further details
> +on the various fileds passed in the key derivation request.
> +
> +On success, the snp_derived_key_resp.data will contains the derived key
> +value.
> diff --git a/drivers/virt/coco/sevguest/sevguest.c b/drivers/virt/coco/sevguest/sevguest.c
> index d029a98ad088..621b1c5a9cfc 100644
> --- a/drivers/virt/coco/sevguest/sevguest.c
> +++ b/drivers/virt/coco/sevguest/sevguest.c
> @@ -303,6 +303,50 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_user_guest_reque
> return rc;
> }
>
> +static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_user_guest_request *arg)
> +{
> + struct snp_guest_crypto *crypto = snp_dev->crypto;
> + struct snp_derived_key_resp *resp;
> + struct snp_derived_key_req req;
> + int rc, resp_len;
> +
> + if (!arg->req_data || !arg->resp_data)
> + return -EINVAL;
> +
> + /* Copy the request payload from the userspace */
> + if (copy_from_user(&req, (void __user *)arg->req_data, sizeof(req)))
> + return -EFAULT;
> +
> + /* Message version must be non-zero */
> + if (!req.msg_version)
> + 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(resp->data) + crypto->a_len;
> + resp = kzalloc(resp_len, GFP_KERNEL_ACCOUNT);
The length of resp->data is 64 bytes; I assume crypto->a_len is not a
lot more (and probably known in advance for AES GCM). Maybe use a
buffer on the stack instead of allocating and freeing?
> + if (!resp)
> + return -ENOMEM;
> +
> + /* Issue the command to get the attestation report */
> + rc = handle_guest_request(snp_dev, req.msg_version, SNP_MSG_KEY_REQ,
> + &req.data, sizeof(req.data), 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);
Since resp contains key material, I think you should explicit_memzero()
it before freeing, so the key bytes don't linger around in unused
memory. I'm not sure if any copies are made inside the
handle_guest_request call above; maybe zero these as well.
-Dov
> + 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);
> @@ -320,6 +364,10 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long
> ret = get_report(snp_dev, &input);
> break;
> }
> + case SNP_GET_DERIVED_KEY: {
> + ret = get_derived_key(snp_dev, &input);
> + break;
> + }
> default:
> break;
> }
> diff --git a/include/uapi/linux/sev-guest.h b/include/uapi/linux/sev-guest.h
> index e8cfd15133f3..621a9167df7a 100644
> --- a/include/uapi/linux/sev-guest.h
> +++ b/include/uapi/linux/sev-guest.h
> @@ -36,9 +36,33 @@ struct snp_user_guest_request {
> __u64 fw_err;
> };
>
> +struct __snp_derived_key_req {
> + __u32 root_key_select;
> + __u32 rsvd;
> + __u64 guest_field_select;
> + __u32 vmpl;
> + __u32 guest_svn;
> + __u64 tcb_version;
> +};
> +
> +struct snp_derived_key_req {
> + /* message version number (must be non-zero) */
> + __u8 msg_version;
> +
> + struct __snp_derived_key_req data;
> +};
> +
> +struct snp_derived_key_resp {
> + /* response data, see SEV-SNP spec for the format */
> + __u8 data[64];
> +};
> +
> #define SNP_GUEST_REQ_IOC_TYPE 'S'
>
> /* Get SNP attestation report */
> #define SNP_GET_REPORT _IOWR(SNP_GUEST_REQ_IOC_TYPE, 0x0, struct snp_user_guest_request)
>
> +/* Get a derived key from the root */
> +#define SNP_GET_DERIVED_KEY _IOWR(SNP_GUEST_REQ_IOC_TYPE, 0x1, struct snp_user_guest_request)
> +
> #endif /* __UAPI_LINUX_SEV_GUEST_H_ */
>
next prev parent reply other threads:[~2021-08-31 19:01 UTC|newest]
Thread overview: 123+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-20 15:18 [PATCH Part1 v5 00/38] Add AMD Secure Nested Paging (SEV-SNP) Guest Support Brijesh Singh
2021-08-20 15:18 ` [PATCH Part1 v5 01/38] x86/mm: Add sev_feature_enabled() helper Brijesh Singh
2021-08-20 15:18 ` [PATCH Part1 v5 02/38] x86/sev: Shorten GHCB terminate macro names Brijesh Singh
2021-08-20 15:18 ` [PATCH Part1 v5 03/38] x86/sev: Get rid of excessive use of defines Brijesh Singh
2021-08-20 15:18 ` [PATCH Part1 v5 04/38] x86/head64: Carve out the guest encryption postprocessing into a helper Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 05/38] x86/sev: Define the Linux specific guest termination reasons Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 06/38] x86/sev: Save the negotiated GHCB version Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 07/38] x86/sev: Add support for hypervisor feature VMGEXIT Brijesh Singh
2021-08-23 9:47 ` Borislav Petkov
2021-08-23 18:25 ` Brijesh Singh
2021-08-23 18:34 ` Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 08/38] x86/sev: Check SEV-SNP features support Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 09/38] x86/sev: Add a helper for the PVALIDATE instruction Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 10/38] x86/sev: Check the vmpl level Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 11/38] x86/compressed: Add helper for validating pages in the decompression stage Brijesh Singh
2021-08-23 14:16 ` Borislav Petkov
2021-08-23 18:55 ` Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 12/38] x86/compressed: Register GHCB memory when SEV-SNP is active Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 13/38] x86/sev: " Brijesh Singh
2021-08-23 17:35 ` Borislav Petkov
2021-08-23 18:56 ` Brijesh Singh
2021-08-23 19:45 ` [PATCH] x86/sev: Remove do_early_exception() forward declarations Borislav Petkov
2021-08-23 20:06 ` Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 14/38] x86/sev: Add helper for validating pages in early enc attribute changes Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 15/38] x86/kernel: Make the bss.decrypted section shared in RMP table Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 16/38] x86/kernel: Validate rom memory before accessing when SEV-SNP is active Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 17/38] x86/mm: Add support to validate memory when changing C-bit Brijesh Singh
2021-08-25 11:06 ` Borislav Petkov
2021-08-25 13:54 ` Brijesh Singh
2021-08-25 14:00 ` Borislav Petkov
2021-08-27 17:09 ` Borislav Petkov
2021-08-20 15:19 ` [PATCH Part1 v5 18/38] KVM: SVM: Define sev_features and vmpl field in the VMSA Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 19/38] KVM: SVM: Create a separate mapping for the SEV-ES save area Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 20/38] KVM: SVM: Create a separate mapping for the GHCB " Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 21/38] KVM: SVM: Update the SEV-ES save area mapping Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 22/38] x86/sev: Use SEV-SNP AP creation to start secondary CPUs Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 23/38] x86/head/64: set up a startup %gs for stack protector Brijesh Singh
2021-08-25 14:29 ` Borislav Petkov
2021-08-25 15:18 ` Michael Roth
2021-08-25 16:29 ` Borislav Petkov
2021-08-27 13:38 ` Michael Roth
2021-08-31 8:03 ` Borislav Petkov
2021-08-31 23:30 ` Michael Roth
2021-08-25 15:07 ` Joerg Roedel
2021-08-25 17:07 ` Michael Roth
2021-08-20 15:19 ` [PATCH Part1 v5 24/38] x86/sev: move MSR-based VMGEXITs for CPUID to helper Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 25/38] KVM: x86: move lookup of indexed CPUID leafs " Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 26/38] x86/compressed/acpi: move EFI config table access to common code Brijesh Singh
2021-08-25 15:18 ` Borislav Petkov
2021-08-25 17:14 ` Michael Roth
2021-08-20 15:19 ` [PATCH Part1 v5 27/38] x86/boot: Add Confidential Computing type to setup_data Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 28/38] x86/compressed/64: enable SEV-SNP-validated CPUID in #VC handler Brijesh Singh
2021-08-25 19:19 ` Borislav Petkov
2021-08-27 16:46 ` Michael Roth
2021-08-31 10:04 ` Borislav Petkov
2021-09-01 1:03 ` Michael Roth
2021-09-02 10:53 ` Borislav Petkov
2021-08-20 15:19 ` [PATCH Part1 v5 29/38] x86/boot: add a pointer to Confidential Computing blob in bootparams Brijesh Singh
2021-08-27 13:51 ` Borislav Petkov
2021-08-27 18:48 ` Michael Roth
2021-08-20 15:19 ` [PATCH Part1 v5 30/38] x86/compressed/64: store Confidential Computing blob address " Brijesh Singh
2021-08-27 14:15 ` Borislav Petkov
2021-08-27 19:09 ` Michael Roth
2021-08-31 10:26 ` Borislav Petkov
2021-08-20 15:19 ` [PATCH Part1 v5 31/38] x86/compressed/64: add identity mapping for Confidential Computing blob Brijesh Singh
2021-08-27 14:43 ` Borislav Petkov
2021-08-20 15:19 ` [PATCH Part1 v5 32/38] x86/sev: enable SEV-SNP-validated CPUID in #VC handlers Brijesh Singh
2021-08-27 15:18 ` Borislav Petkov
2021-08-27 15:47 ` Brijesh Singh
2021-08-27 16:56 ` Borislav Petkov
2021-08-27 18:39 ` Michael Roth
2021-08-27 18:32 ` Michael Roth
2021-08-30 16:03 ` Michael Roth
2021-08-31 16:22 ` Borislav Petkov
2021-09-01 1:16 ` Michael Roth
2021-09-02 11:05 ` Borislav Petkov
2021-08-20 15:19 ` [PATCH Part1 v5 33/38] x86/sev: Provide support for SNP guest request NAEs Brijesh Singh
2021-08-27 17:44 ` Borislav Petkov
2021-08-27 18:07 ` Brijesh Singh
2021-08-27 18:13 ` Borislav Petkov
2021-08-27 18:27 ` Brijesh Singh
2021-08-27 18:38 ` Borislav Petkov
2021-08-27 19:57 ` Tom Lendacky
2021-08-27 20:17 ` Borislav Petkov
2021-08-27 20:31 ` Tom Lendacky
2021-08-20 15:19 ` [PATCH Part1 v5 34/38] x86/sev: Add snp_msg_seqno() helper Brijesh Singh
2021-08-27 18:41 ` Borislav Petkov
2021-08-30 15:07 ` Brijesh Singh
2021-09-02 11:26 ` Borislav Petkov
2021-09-02 15:27 ` Brijesh Singh
2021-08-31 20:46 ` Dov Murik
2021-08-31 21:13 ` Brijesh Singh
2021-09-09 14:54 ` Peter Gonda
2021-09-09 15:26 ` Brijesh Singh
2021-09-09 15:43 ` Peter Gonda
2021-09-09 16:17 ` Brijesh Singh
2021-09-09 16:21 ` Peter Gonda
2021-09-09 19:26 ` Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 35/38] x86/sev: Register SNP guest request platform device Brijesh Singh
2021-08-31 11:37 ` Dov Murik
2021-08-31 16:03 ` Brijesh Singh
2021-09-02 16:40 ` Borislav Petkov
2021-09-02 19:58 ` Brijesh Singh
2021-09-03 8:15 ` Dov Murik
2021-09-03 12:08 ` Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 36/38] virt: Add SEV-SNP guest driver Brijesh Singh
2021-09-06 17:38 ` Borislav Petkov
2021-09-07 13:35 ` Brijesh Singh
2021-09-08 13:44 ` Borislav Petkov
2021-08-20 15:19 ` [PATCH Part1 v5 37/38] virt: sevguest: Add support to derive key Brijesh Singh
2021-08-31 18:59 ` Dov Murik [this message]
2021-08-31 21:04 ` Brijesh Singh
2021-09-01 5:33 ` Dov Murik
2021-09-08 14:00 ` Borislav Petkov
2021-09-08 21:44 ` Brijesh Singh
2021-08-20 15:19 ` [PATCH Part1 v5 38/38] virt: sevguest: Add support to get extended report Brijesh Singh
2021-08-31 20:22 ` Dov Murik
2021-08-31 21:11 ` Brijesh Singh
2021-09-01 8:32 ` Dov Murik
2021-09-08 17:53 ` Borislav Petkov
2021-09-15 11:46 ` Brijesh Singh
2021-09-15 10:02 ` Dr. David Alan Gilbert
2021-09-15 11:53 ` Brijesh Singh
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