From patchwork Fri Mar 29 22:58:34 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Roth X-Patchwork-Id: 784156 Received: from NAM02-DM3-obe.outbound.protection.outlook.com (mail-dm3nam02on2086.outbound.protection.outlook.com [40.107.95.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1559F13E408; Fri, 29 Mar 2024 23:06:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.107.95.86 ARC-Seal: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711753587; cv=fail; b=uVxzxBp9ua9ojUje7iOTm6ElFMdMHmdPYW0cUn6bjO7rF9rpTnSFzjBQNwx9spej1SZwD2d3ddUJSL7R2Behss3Yf5iVrst2nE0eE8Kf9rwbOVWN2G2Wo4zkjF8M1GkC3ISI2lp8VHqirYlYmhXAcrvJ0aWXLcJjioCaJ2gdSfo= ARC-Message-Signature: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711753587; c=relaxed/simple; bh=KalEbdqRGRxS5KjJYNiUkYknvhPkZuxd2fBb0cCgSeE=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=BOktB9YS73vaB1FyI/btKNHhjK+iudqpuFu8zlcHRObZnEOUWR6aTCQIvgQSBjZ5ifi/zYzsQla9sGYZzlKbXFWcfl/2AMUZeZb7bjFZR/d+d1/oa1Sur7wYqaGcpelZf1ezG2GCIarZyD2juMhQo2HIkLuvXaJvQDhjINv0lNo= ARC-Authentication-Results: i=2; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com; spf=fail smtp.mailfrom=amd.com; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b=EQB9OIea; arc=fail smtp.client-ip=40.107.95.86 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=amd.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b="EQB9OIea" ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=CFHIOL2v24wJaO2yisaKcXeiUV+EUvOpK9IZEbVfDGmni78YdT0lMZvfpeYqipud8yhZ4gHslAMcdAQuRzk7xciD9c1598D8uZ49rcSjondc9yXX8RRPFMtdylgd6HqoBsseYuRzulAUZ37Zap4H6hxM73NbuAGbOPlloxcddZtPSqnauMXbFezr+3Ef+E4FyYSzxbLkuR8lcNsckXvl6B/FSK28NgDvprWlY8C8e9jc5TSQrufwnBwlVZnEXN40saecPKgxuvpcmxoS//9XPnw1OWEwqx0KLvA+oD1DiQhvgTJdmWJjEsN2gPhhKfBV0SxUD3Yml5RkRt2ef4lrrw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=xP7eiDAex+6DfGwbSIMsn9LpYXQmn4Kn5QQfRgVRAv8=; b=ZvZnMU/ezwI47YqFGuq1hiunzr+cbZzvidUZhx+bqCC51581eV856EBTaw2ucSXMHjUU1fVSs08ZRxWyVUFU+/wF/uRF3k0Iix6KbiwZoY0YL5B3dlrL7oOsRCnqkL9AGsjIswEnCUoJQRUfeFtAVIXwhn/edhT3VN+ysHS188w6CWhK5PohJGWVw08l9Xox6RHmIBsgEiWCkMUKnHVeK2jJ4PAXzapHJz+ZZO0o4AoeC3uqTbbl4u1prerJUGbjuHsknwLjMpCEyTpCOFWaDk8hmEZmyCwnK9HDF7HGK0rLEgAVApg+HWWMbhRvvlLZu2ADZx9vo2DqA6wr0mZLDw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=vger.kernel.org smtp.mailfrom=amd.com; dmarc=pass (p=quarantine sp=quarantine pct=100) action=none header.from=amd.com; dkim=none (message not signed); arc=none (0) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=xP7eiDAex+6DfGwbSIMsn9LpYXQmn4Kn5QQfRgVRAv8=; b=EQB9OIeaxFjsOzOPKNd8cAEUq7aSSCsc1yGTlBbuIZbxYtxUCa2I+XTMLCPgKruQYscZzJF92fnmoACvtFHOjpstNXrXbQkb38Z1Kc0qn5MP4NGE+3/CUP4fiFbfGWpQnglJXfkKUuHWghjC56ZmuNe921Y5nuLVeUGWMqB3KLI= Received: from DM6PR01CA0015.prod.exchangelabs.com (2603:10b6:5:296::20) by DS7PR12MB8322.namprd12.prod.outlook.com (2603:10b6:8:ed::13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7409.32; Fri, 29 Mar 2024 23:06:21 +0000 Received: from DS1PEPF00017092.namprd03.prod.outlook.com (2603:10b6:5:296:cafe::60) by DM6PR01CA0015.outlook.office365.com (2603:10b6:5:296::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7409.40 via Frontend Transport; Fri, 29 Mar 2024 23:06:21 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 165.204.84.17) smtp.mailfrom=amd.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=amd.com; Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C Received: from SATLEXMB04.amd.com (165.204.84.17) by DS1PEPF00017092.mail.protection.outlook.com (10.167.17.135) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.7409.10 via Frontend Transport; Fri, 29 Mar 2024 23:06:21 +0000 Received: from localhost (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.35; Fri, 29 Mar 2024 18:06:20 -0500 From: Michael Roth To: CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: [PATCH v12 28/29] crypto: ccp: Add the SNP_{PAUSE, RESUME}_ATTESTATION commands Date: Fri, 29 Mar 2024 17:58:34 -0500 Message-ID: <20240329225835.400662-29-michael.roth@amd.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240329225835.400662-1-michael.roth@amd.com> References: <20240329225835.400662-1-michael.roth@amd.com> Precedence: bulk X-Mailing-List: linux-crypto@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: SATLEXMB03.amd.com (10.181.40.144) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS1PEPF00017092:EE_|DS7PR12MB8322:EE_ X-MS-Office365-Filtering-Correlation-Id: cc6f20e1-32a1-4880-c374-08dc5044d987 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:165.204.84.17; CTRY:US; LANG:en; SCL:1; SRV:; IPV:CAL; SFV:NSPM; H:SATLEXMB04.amd.com; PTR:InfoDomainNonexistent; CAT:NONE; SFS:(13230031)(36860700004)(1800799015)(82310400014)(376005)(7416005); DIR:OUT; SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Mar 2024 23:06:21.6538 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: cc6f20e1-32a1-4880-c374-08dc5044d987 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d; Ip=[165.204.84.17]; Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: DS1PEPF00017092.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR12MB8322 These commands can be used to pause servicing of guest attestation requests. This useful when updating the reported TCB or signing key with commands such as SNP_SET_CONFIG/SNP_COMMIT/SNP_VLEK_LOAD, since they may in turn require updates to userspace-supplied certificates, and if an attestation request happens to be in-flight at the time those updates are occurring there is potential for a guest to receive a certificate blob that is out of sync with the effective signing key for the attestation report. These interfaces also provide some versatility with how similar firmware/certificate update activities can be handled in the future. Signed-off-by: Michael Roth Reviewed-by: Tom Lendacky --- Documentation/virt/coco/sev-guest.rst | 50 +++++++++++++++++++++++++-- arch/x86/include/asm/sev.h | 4 +++ arch/x86/virt/svm/sev.c | 43 +++++++++++++++++++++++ drivers/crypto/ccp/sev-dev.c | 47 +++++++++++++++++++++++++ include/uapi/linux/psp-sev.h | 12 +++++++ 5 files changed, 154 insertions(+), 2 deletions(-) diff --git a/Documentation/virt/coco/sev-guest.rst b/Documentation/virt/coco/sev-guest.rst index e1eaf6a830ce..dd5cf2098afd 100644 --- a/Documentation/virt/coco/sev-guest.rst +++ b/Documentation/virt/coco/sev-guest.rst @@ -128,8 +128,6 @@ the SEV-SNP specification for further details. The SNP_GET_EXT_REPORT ioctl is similar to the SNP_GET_REPORT. The difference is related to the additional certificate data that is returned with the report. -The certificate data returned is being provided by the hypervisor through the -SNP_SET_EXT_CONFIG. The ioctl uses the SNP_GUEST_REQUEST (MSG_REPORT_REQ) command provided by the SEV-SNP firmware to get the attestation report. @@ -176,6 +174,54 @@ to SNP_CONFIG command defined in the SEV-SNP spec. The current values of the firmware parameters affected by this command can be queried via SNP_PLATFORM_STATUS. +2.7 SNP_PAUSE_ATTESTATION / SNP_RESUME_ATTESTATION +-------------------------------------------------- +:Technology: sev-snp +:Type: hypervisor ioctl cmd +:Parameters (out): struct sev_user_data_snp_pause_transaction +:Returns (out): 0 on success, -negative on error + +When requesting attestation reports, SNP guests have the option of issuing +an extended guest request which allows host userspace to supply additional +certificate data that can be used to validate the signature used to sign +the attestation report. This signature is generated using a key that is +derived from the reported TCB that can be set via the SNP_SET_CONFIG and +SNP_COMMIT ioctls, so the accompanying certificate data needs to be kept in +sync with the changes made to the reported TCB via these ioctls. + +Similarly, interfaces like SNP_LOAD_VLEK can modify the key used to sign +the attestation reports, which may in turn require updating the certificate +data provided to guests via extended guest requests. + +To allow for updating the reported TCB, endorsement key, and any certificate +data in a manner that is atomic to guests, the SNP_PAUSE_ATTESTATION and +SNP_RESUME_ATTESTATION commands are provided. + +After SNP_PAUSE_ATTESTATION is issued, any attestation report requests via +extended guest requests that are in-progress, or received after +SNP_PAUSE_ATTESTATION is issued, will result in the guest receiving a +GHCB-defined error message instructing it to retry the request. Once all +the desired reported TCB, endorsement keys, or certificate data updates +are completed on the host, the SNP_RESUME_ATTESTATION command must be +issued to allow guest attestation requests to proceed. + +In general, hosts should serialize updates of this sort and never have more +than 1 outstanding transaction in flight that could result in the +interleaving of multiple SNP_PAUSE_ATTESTATION/SNP_RESUME_ATTESTATION pairs. +To guard against this, SNP_PAUSE_ATTESTATION will fail if another process +has already paused attestation requests. + +However, there may be occassions where a transaction needs to be aborted due +to unexpected activity in userspace such as timeouts, crashes, etc., so +SNP_RESUME_ATTESTATION will always succeed. Nonetheless, this could +potentially lead to SNP_RESUME_ATTESTATION being called out of sequence, so +to allow for callers of SNP_{PAUSE,RESUME}_ATTESTATION to detect such +occurrences, each ioctl will return a transaction ID in the response so the +caller can monitor whether the start/end ID both match. If they don't, the +caller should assume that attestation has been paused/resumed unexpectedly, +and take whatever measures it deems necessary such as logging, reporting, +auditing the sequence of events. + 3. SEV-SNP CPUID Enforcement ============================ diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index 234a998e2d2d..975e92005438 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -272,6 +272,8 @@ int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, u32 asid, bool immut int rmp_make_shared(u64 pfn, enum pg_level level); void snp_leak_pages(u64 pfn, unsigned int npages); void kdump_sev_callback(void); +int snp_pause_attestation(u64 *transaction_id); +void snp_resume_attestation(u64 *transaction_id); #else static inline bool snp_probe_rmptable_info(void) { return false; } static inline int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level) { return -ENODEV; } @@ -285,6 +287,8 @@ static inline int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, u32 as static inline int rmp_make_shared(u64 pfn, enum pg_level level) { return -ENODEV; } static inline void snp_leak_pages(u64 pfn, unsigned int npages) {} static inline void kdump_sev_callback(void) { } +static inline int snp_pause_attestation(u64 *transaction_id) { return 0; } +static inline void snp_resume_attestation(u64 *transaction_id) {} #endif #endif diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c index ab0e8448bb6e..09d62870306b 100644 --- a/arch/x86/virt/svm/sev.c +++ b/arch/x86/virt/svm/sev.c @@ -70,6 +70,11 @@ static DEFINE_SPINLOCK(snp_leaked_pages_list_lock); static unsigned long snp_nr_leaked_pages; +/* For synchronizing TCB/certificate updates with extended guest requests */ +static DEFINE_MUTEX(snp_pause_attestation_lock); +static u64 snp_transaction_id; +static bool snp_attestation_paused; + #undef pr_fmt #define pr_fmt(fmt) "SEV-SNP: " fmt @@ -568,3 +573,41 @@ void kdump_sev_callback(void) if (cc_platform_has(CC_ATTR_HOST_SEV_SNP)) wbinvd(); } + +int snp_pause_attestation(u64 *transaction_id) +{ + mutex_lock(&snp_pause_attestation_lock); + + if (snp_attestation_paused) { + mutex_unlock(&snp_pause_attestation_lock); + return -EBUSY; + } + + /* + * The actual transaction ID update will happen when + * snp_resume_attestation() is called, so return + * the *anticipated* transaction ID that will be + * returned by snp_resume_attestation(). This is + * to ensure that unbalanced/aborted transactions will + * be noticeable when the caller that started the + * transaction calls snp_resume_attestation(). + */ + *transaction_id = snp_transaction_id + 1; + snp_attestation_paused = true; + + mutex_unlock(&snp_pause_attestation_lock); + + return 0; +} +EXPORT_SYMBOL_GPL(snp_pause_attestation); + +void snp_resume_attestation(u64 *transaction_id) +{ + mutex_lock(&snp_pause_attestation_lock); + + snp_attestation_paused = false; + *transaction_id = ++snp_transaction_id; + + mutex_unlock(&snp_pause_attestation_lock); +} +EXPORT_SYMBOL_GPL(snp_resume_attestation); diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c index 97a7959406ee..7eb18a273731 100644 --- a/drivers/crypto/ccp/sev-dev.c +++ b/drivers/crypto/ccp/sev-dev.c @@ -2060,6 +2060,47 @@ static int sev_ioctl_do_snp_vlek_load(struct sev_issue_cmd *argp, bool writable) return ret; } +static int sev_ioctl_do_snp_pause_attestation(struct sev_issue_cmd *argp, bool writable) +{ + struct sev_user_data_snp_pause_attestation transaction = {0}; + struct sev_device *sev = psp_master->sev_data; + int ret; + + if (!sev->snp_initialized || !argp->data) + return -EINVAL; + + if (!writable) + return -EPERM; + + ret = snp_pause_attestation(&transaction.id); + if (ret) + return ret; + + if (copy_to_user((void __user *)argp->data, &transaction, sizeof(transaction))) + return -EFAULT; + + return 0; +} + +static int sev_ioctl_do_snp_resume_attestation(struct sev_issue_cmd *argp, bool writable) +{ + struct sev_user_data_snp_pause_attestation transaction = {0}; + struct sev_device *sev = psp_master->sev_data; + + if (!sev->snp_initialized || !argp->data) + return -EINVAL; + + if (!writable) + return -EPERM; + + snp_resume_attestation(&transaction.id); + + if (copy_to_user((void __user *)argp->data, &transaction, sizeof(transaction))) + return -EFAULT; + + return 0; +} + static long sev_ioctl(struct file *file, unsigned int ioctl, unsigned long arg) { void __user *argp = (void __user *)arg; @@ -2123,6 +2164,12 @@ static long sev_ioctl(struct file *file, unsigned int ioctl, unsigned long arg) case SNP_VLEK_LOAD: ret = sev_ioctl_do_snp_vlek_load(&input, writable); break; + case SNP_PAUSE_ATTESTATION: + ret = sev_ioctl_do_snp_pause_attestation(&input, writable); + break; + case SNP_RESUME_ATTESTATION: + ret = sev_ioctl_do_snp_resume_attestation(&input, writable); + break; default: ret = -EINVAL; goto out; diff --git a/include/uapi/linux/psp-sev.h b/include/uapi/linux/psp-sev.h index 2289b7c76c59..7b35b2814a99 100644 --- a/include/uapi/linux/psp-sev.h +++ b/include/uapi/linux/psp-sev.h @@ -32,6 +32,8 @@ enum { SNP_COMMIT, SNP_SET_CONFIG, SNP_VLEK_LOAD, + SNP_PAUSE_ATTESTATION, + SNP_RESUME_ATTESTATION, SEV_MAX, }; @@ -241,6 +243,16 @@ struct sev_user_data_snp_wrapped_vlek_hashstick { __u8 data[432]; /* In */ } __packed; +/** + * struct sev_user_data_snp_pause_attestation - metadata for pausing attestation + * + * @id: the ID of the transaction started/ended by a call to SNP_PAUSE_ATTESTATION + * or SNP_RESUME_ATTESTATION, respectively. + */ +struct sev_user_data_snp_pause_attestation { + __u64 id; /* Out */ +} __packed; + /** * struct sev_issue_cmd - SEV ioctl parameters *