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2023-06-09virt: sevguest: Add CONFIG_CRYPTO dependencyArnd Bergmann1-0/+1
This driver fails to link when CRYPTO is disabled, or in a loadable module: WARNING: unmet direct dependencies detected for CRYPTO_GCM WARNING: unmet direct dependencies detected for CRYPTO_AEAD2 Depends on [m]: CRYPTO [=m] Selected by [y]: - SEV_GUEST [=y] && VIRT_DRIVERS [=y] && AMD_MEM_ENCRYPT [=y] x86_64-linux-ld: crypto/aead.o: in function `crypto_register_aeads': Fixes: fce96cf04430 ("virt: Add SEV-SNP guest driver") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20230117171416.2715125-1-arnd@kernel.org
2023-03-21x86/sev: Change snp_guest_issue_request()'s fw_err argumentDionna Glaze1-33/+39
The GHCB specification declares that the firmware error value for a guest request will be stored in the lower 32 bits of EXIT_INFO_2. The upper 32 bits are for the VMM's own error code. The fw_err argument to snp_guest_issue_request() is thus a misnomer, and callers will need access to all 64 bits. The type of unsigned long also causes problems, since sw_exit_info2 is u64 (unsigned long long) vs the argument's unsigned long*. Change this type for issuing the guest request. Pass the ioctl command struct's error field directly instead of in a local variable, since an incomplete guest request may not set the error code, and uninitialized stack memory would be written back to user space. The firmware might not even be called, so bookend the call with the no firmware call error and clear the error. Since the "fw_err" field is really exitinfo2 split into the upper bits' vmm error code and lower bits' firmware error code, convert the 64 bit value to a union. [ bp: - Massage commit message - adjust code - Fix a build issue as Reported-by: kernel test robot <lkp@intel.com> Link: https://lore.kernel.org/oe-kbuild-all/202303070609.vX6wp2Af-lkp@intel.com - print exitinfo2 in hex Tom: - Correct -EIO exit case. ] Signed-off-by: Dionna Glaze <dionnaglaze@google.com> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20230214164638.1189804-5-dionnaglaze@google.com Link: https://lore.kernel.org/r/20230307192449.24732-12-bp@alien8.de
2023-03-21virt/coco/sev-guest: Double-buffer messagesDionna Glaze1-4/+23
The encryption algorithms read and write directly to shared unencrypted memory, which may leak information as well as permit the host to tamper with the message integrity. Instead, copy whole messages in or out as needed before doing any computation on them. Fixes: d5af44dde546 ("x86/sev: Provide support for SNP guest request NAEs") Signed-off-by: Dionna Glaze <dionnaglaze@google.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20230214164638.1189804-3-dionnaglaze@google.com
2023-03-13virt/coco/sev-guest: Add throttling awarenessDionna Glaze1-1/+18
A potentially malicious SEV guest can constantly hammer the hypervisor using this driver to send down requests and thus prevent or at least considerably hinder other guests from issuing requests to the secure processor which is a shared platform resource. Therefore, the host is permitted and encouraged to throttle such guest requests. Add the capability to handle the case when the hypervisor throttles excessive numbers of requests issued by the guest. Otherwise, the VM platform communication key will be disabled, preventing the guest from attesting itself. Realistically speaking, a well-behaved guest should not even care about throttling. During its lifetime, it would end up issuing a handful of requests which the hardware can easily handle. This is more to address the case of a malicious guest. Such guest should get throttled and if its VMPCK gets disabled, then that's its own wrongdoing and perhaps that guest even deserves it. To the implementation: the hypervisor signals with SNP_GUEST_REQ_ERR_BUSY that the guest requests should be throttled. That error code is returned in the upper 32-bit half of exitinfo2 and this is part of the GHCB spec v2. So the guest is given a throttling period of 1 minute in which it retries the request every 2 seconds. This is a good default but if it turns out to not pan out in practice, it can be tweaked later. For safety, since the encryption algorithm in GHCBv2 is AES_GCM, control must remain in the kernel to complete the request with the current sequence number. Returning without finishing the request allows the guest to make another request but with different message contents. This is IV reuse, and breaks cryptographic protections. [ bp: - Rewrite commit message and do a simplified version. - The stable tags are supposed to denote that a cleanup should go upfront before backporting this so that any future fixes to this can preserve the sanity of the backporter(s). ] Fixes: d5af44dde546 ("x86/sev: Provide support for SNP guest request NAEs") Signed-off-by: Dionna Glaze <dionnaglaze@google.com> Co-developed-by: Borislav Petkov (AMD) <bp@alien8.de> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Cc: <stable@kernel.org> # d6fd48eff750 ("virt/coco/sev-guest: Check SEV_SNP attribute at probe time") Cc: <stable@kernel.org> # 970ab823743f (" virt/coco/sev-guest: Simplify extended guest request handling") Cc: <stable@kernel.org> # c5a338274bdb ("virt/coco/sev-guest: Remove the disable_vmpck label in handle_guest_request()") Cc: <stable@kernel.org> # 0fdb6cc7c89c ("virt/coco/sev-guest: Carve out the request issuing logic into a helper") Cc: <stable@kernel.org> # d25bae7dc7b0 ("virt/coco/sev-guest: Do some code style cleanups") Cc: <stable@kernel.org> # fa4ae42cc60a ("virt/coco/sev-guest: Convert the sw_exit_info_2 checking to a switch-case") Link: https://lore.kernel.org/r/20230214164638.1189804-2-dionnaglaze@google.com
2023-03-13virt/coco/sev-guest: Do some code style cleanupsBorislav Petkov (AMD)1-6/+2
Remove unnecessary linebreaks, make the code more compact. No functional changes. Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Link: https://lore.kernel.org/r/20230307192449.24732-7-bp@alien8.de
2023-03-13virt/coco/sev-guest: Carve out the request issuing logic into a helperBorislav Petkov (AMD)1-17/+27
This makes the code flow a lot easier to follow. No functional changes. [ Tom: touchups. ] Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20230307192449.24732-6-bp@alien8.de
2023-03-13virt/coco/sev-guest: Remove the disable_vmpck label in handle_guest_request()Borislav Petkov (AMD)1-6/+4
Call the function directly instead. No functional changes. Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Link: https://lore.kernel.org/r/20230307192449.24732-5-bp@alien8.de
2023-03-13virt/coco/sev-guest: Simplify extended guest request handlingBorislav Petkov (AMD)1-22/+26
Return a specific error code - -ENOSPC - to signal the too small cert data buffer instead of checking exit code and exitinfo2. While at it, hoist the *fw_err assignment in snp_issue_guest_request() so that a proper error value is returned to the callers. [ Tom: check override_err instead of err. ] Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20230307192449.24732-4-bp@alien8.de
2023-03-13virt/coco/sev-guest: Check SEV_SNP attribute at probe timeBorislav Petkov (AMD)1-0/+3
No need to check it on every ioctl. And yes, this is a common SEV driver but it does only SNP-specific operations currently. This can be revisited later, when more use cases appear. No functional changes. Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Link: https://lore.kernel.org/r/20230307192449.24732-3-bp@alien8.de
2023-03-01virt/sev-guest: Return -EIO if certificate buffer is not large enoughTom Lendacky1-3/+17
Commit 47894e0fa6a5 ("virt/sev-guest: Prevent IV reuse in the SNP guest driver") changed the behavior associated with the return value when the caller does not supply a large enough certificate buffer. Prior to the commit a value of -EIO was returned. Now, 0 is returned. This breaks the established ABI with the user. Change the code to detect the buffer size error and return -EIO. Fixes: 47894e0fa6a5 ("virt/sev-guest: Prevent IV reuse in the SNP guest driver") Reported-by: Larry Dewey <larry.dewey@amd.com> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Tested-by: Larry Dewey <larry.dewey@amd.com> Cc: <stable@kernel.org> Link: https://lore.kernel.org/r/2afbcae6daf13f7ad5a4296692e0a0fe1bc1e4ee.1677083979.git.thomas.lendacky@amd.com
2022-12-14Merge tag 'x86_sev_for_v6.2' of ↵Linus Torvalds1-3/+2
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 sev updates from Borislav Petkov: - Two minor fixes to the sev-guest driver * tag 'x86_sev_for_v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: virt/sev-guest: Add a MODULE_ALIAS virt/sev-guest: Remove unnecessary free in init_crypto()
2022-12-13Merge tag 'x86_tdx_for_6.2' of ↵Linus Torvalds3-0/+114
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 tdx updates from Dave Hansen: "This includes a single chunk of new functionality for TDX guests which allows them to talk to the trusted TDX module software and obtain an attestation report. This report can then be used to prove the trustworthiness of the guest to a third party and get access to things like storage encryption keys" * tag 'x86_tdx_for_6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: selftests/tdx: Test TDX attestation GetReport support virt: Add TDX guest driver x86/tdx: Add a wrapper to get TDREPORT0 from the TDX Module
2022-11-21virt/sev-guest: Prevent IV reuse in the SNP guest driverPeter Gonda1-14/+70
The AMD Secure Processor (ASP) and an SNP guest use a series of AES-GCM keys called VMPCKs to communicate securely with each other. The IV to this scheme is a sequence number that both the ASP and the guest track. Currently, this sequence number in a guest request must exactly match the sequence number tracked by the ASP. This means that if the guest sees an error from the host during a request it can only retry that exact request or disable the VMPCK to prevent an IV reuse. AES-GCM cannot tolerate IV reuse, see: "Authentication Failures in NIST version of GCM" - Antoine Joux et al. In order to address this, make handle_guest_request() delete the VMPCK on any non successful return. To allow userspace querying the cert_data length make handle_guest_request() save the number of pages required by the host, then have handle_guest_request() retry the request without requesting the extended data, then return the number of pages required back to userspace. [ bp: Massage, incorporate Tom's review comments. ] Fixes: fce96cf044308 ("virt: Add SEV-SNP guest driver") Reported-by: Peter Gonda <pgonda@google.com> Signed-off-by: Peter Gonda <pgonda@google.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Cc: stable@kernel.org Link: https://lore.kernel.org/r/20221116175558.2373112-1-pgonda@google.com
2022-11-17virt: Add TDX guest driverKuppuswamy Sathyanarayanan3-0/+114
TDX guest driver exposes IOCTL interfaces to service TDX guest user-specific requests. Currently, it is only used to allow the user to get the TDREPORT to support TDX attestation. Details about the TDX attestation process are documented in Documentation/x86/tdx.rst, and the IOCTL details are documented in Documentation/virt/coco/tdx-guest.rst. Operations like getting TDREPORT involves sending a blob of data as input and getting another blob of data as output. It was considered to use a sysfs interface for this, but it doesn't fit well into the standard sysfs model for configuring values. It would be possible to do read/write on files, but it would need multiple file descriptors, which would be somewhat messy. IOCTLs seem to be the best fitting and simplest model for this use case. The AMD sev-guest driver also uses the IOCTL interface to support attestation. [Bagas Sanjaya: Ack is for documentation portion] Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com> Reviewed-by: Tony Luck <tony.luck@intel.com> Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com> Acked-by: Kai Huang <kai.huang@intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Wander Lairson Costa <wander@redhat.com> Link: https://lore.kernel.org/all/20221116223820.819090-3-sathyanarayanan.kuppuswamy%40linux.intel.com
2022-11-08virt/sev-guest: Add a MODULE_ALIASCole Robinson1-0/+1
Autoload the driver when, for example, SNP init code creates the corresponding platform device. [ bp: Rewrite commit message. ] Fixes: fce96cf04430 ("virt: Add SEV-SNP guest driver") Signed-off-by: Cole Robinson <crobinso@redhat.com> Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Tom Lendacky <thomas.lendacky@amd.com> Link: https://lore.kernel.org/r/ff480c5e688eb0a72a4db0a29c7b1bb54c45bfd4.1667594253.git.crobinso@redhat.com
2022-10-27virt/sev-guest: Remove unnecessary free in init_crypto()Rafael Mendonca1-3/+1
If the memory allocation for the auth tag fails, then there is no need to free it. Fixes: fce96cf04430 ("virt: Add SEV-SNP guest driver") Signed-off-by: Rafael Mendonca <rafaelmendsr@gmail.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20221018015425.887891-1-rafaelmendsr@gmail.com
2022-07-19virt: sev-guest: Pass the appropriate argument type to iounmap()Tom Lendacky1-3/+6
Fix a sparse warning in sev_guest_probe() where the wrong argument type is provided to iounmap(). Fixes: fce96cf04430 ("virt: Add SEV-SNP guest driver") Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/202207150617.jqwQ0Rpz-lkp@intel.com
2022-05-24Merge tag 'x86_sev_for_v5.19_rc1' of ↵Linus Torvalds4-0/+822
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull AMD SEV-SNP support from Borislav Petkov: "The third AMD confidential computing feature called Secure Nested Paging. Add to confidential guests the necessary memory integrity protection against malicious hypervisor-based attacks like data replay, memory remapping and others, thus achieving a stronger isolation from the hypervisor. At the core of the functionality is a new structure called a reverse map table (RMP) with which the guest has a say in which pages get assigned to it and gets notified when a page which it owns, gets accessed/modified under the covers so that the guest can take an appropriate action. In addition, add support for the whole machinery needed to launch a SNP guest, details of which is properly explained in each patch. And last but not least, the series refactors and improves parts of the previous SEV support so that the new code is accomodated properly and not just bolted on" * tag 'x86_sev_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits) x86/entry: Fixup objtool/ibt validation x86/sev: Mark the code returning to user space as syscall gap x86/sev: Annotate stack change in the #VC handler x86/sev: Remove duplicated assignment to variable info x86/sev: Fix address space sparse warning x86/sev: Get the AP jump table address from secrets page x86/sev: Add missing __init annotations to SEV init routines virt: sevguest: Rename the sevguest dir and files to sev-guest virt: sevguest: Change driver name to reflect generic SEV support x86/boot: Put globals that are accessed early into the .data section x86/boot: Add an efi.h header for the decompressor virt: sevguest: Fix bool function returning negative value virt: sevguest: Fix return value check in alloc_shared_pages() x86/sev-es: Replace open-coded hlt-loop with sev_es_terminate() virt: sevguest: Add documentation for SEV-SNP CPUID Enforcement virt: sevguest: Add support to get extended report virt: sevguest: Add support to derive key virt: Add SEV-SNP guest driver x86/sev: Register SEV-SNP guest request platform device x86/sev: Provide support for SNP guest request NAEs ...
2022-04-27x86/sev: Get the AP jump table address from secrets pageBrijesh Singh1-35/+0
The GHCB specification section 2.7 states that when SEV-SNP is enabled, a guest should not rely on the hypervisor to provide the address of the AP jump table. Instead, if a guest BIOS wants to provide an AP jump table, it should record the address in the SNP secrets page so the guest operating system can obtain it directly from there. Fix this on the guest kernel side by having SNP guests use the AP jump table address published in the secrets page rather than issuing a GHCB request to get it. [ mroth: - Improve error handling when ioremap()/memremap() return NULL - Don't mix function calls with declarations - Add missing __init - Tweak commit message ] Fixes: 0afb6b660a6b ("x86/sev: Use SEV-SNP AP creation to start secondary CPUs") Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> Signed-off-by: Michael Roth <michael.roth@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20220422135624.114172-3-michael.roth@amd.com
2022-04-27virt: sevguest: Rename the sevguest dir and files to sev-guestTom Lendacky4-6/+6
Rename the drivers/virt/coco/sevguest directory and files to sev-guest so as to match the driver name. [ bp: Rename Documentation/virt/coco/sevguest.rst too, as reported by sfr: https://lore.kernel.org/r/20220427101059.3bf55262@canb.auug.org.au ] Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/2f5c9cb16e3a67599c8e3170f6c72c8712c47d53.1650464054.git.thomas.lendacky@amd.com
2022-04-21virt: sevguest: Change driver name to reflect generic SEV supportTom Lendacky1-18/+21
During patch review, it was decided the SNP guest driver name should not be SEV-SNP specific, but should be generic for use with anything SEV. However, this feedback was missed and the driver name, and many of the driver functions and structures, are SEV-SNP name specific. Rename the driver to "sev-guest" (to match the misc device that is created) and update some of the function and structure names, too. While in the file, adjust the one pr_err() message to be a dev_err() message so that the message, if issued, uses the driver name. Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/307710bb5515c9088a19fd0b930268c7300479b2.1650464054.git.thomas.lendacky@amd.com
2022-04-14virt: sevguest: Fix bool function returning negative valueHaowen Bai1-1/+1
The function enc_payload() is wrongly declared bool but returns an integer value. Correct it. [ bp: Massage commit message. ] Fixes: fce96cf04430 ("virt: Add SEV-SNP guest driver") Signed-off-by: Haowen Bai <baihaowen@meizu.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/1649930657-10837-1-git-send-email-baihaowen@meizu.com
2022-04-13virt: Add efi_secret module to expose confidential computing secretsDov Murik3-0/+367
The new efi_secret module exposes the confidential computing (coco) EFI secret area via securityfs interface. When the module is loaded (and securityfs is mounted, typically under /sys/kernel/security), a "secrets/coco" directory is created in securityfs. In it, a file is created for each secret entry. The name of each such file is the GUID of the secret entry, and its content is the secret data. This allows applications running in a confidential computing setting to read secrets provided by the guest owner via a secure secret injection mechanism (such as AMD SEV's LAUNCH_SECRET command). Removing (unlinking) files in the "secrets/coco" directory will zero out the secret in memory, and remove the filesystem entry. If the module is removed and loaded again, that secret will not appear in the filesystem. Signed-off-by: Dov Murik <dovmurik@linux.ibm.com> Reviewed-by: Gerd Hoffmann <kraxel@redhat.com> Link: https://lore.kernel.org/r/20220412212127.154182-3-dovmurik@linux.ibm.com Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2022-04-11virt: sevguest: Fix return value check in alloc_shared_pages()Yang Yingliang1-1/+1
If alloc_pages() fails, it returns a NULL pointer. Replace the wrong IS_ERR() check with the proper NULL pointer check. Fixes: fce96cf04430 ("virt: Add SEV-SNP guest driver") Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com> Link: https://lore.kernel.org/r/20220411111213.1477853-1-yangyingliang@huawei.com
2022-04-07virt: sevguest: Add support to get extended reportBrijesh Singh1-2/+90
Version 2 of GHCB specification defines Non-Automatic-Exit (NAE) to get extended guest report which is similar to the SNP_GET_REPORT ioctl. The main difference is related to the additional data that will be returned. That additional data returned is a certificate blob that can be used by the SNP guest user. The certificate blob layout is defined in the GHCB specification. The driver simply treats the blob as a opaque data and copies it to userspace. [ bp: Massage commit message, cast 1st arg of access_ok() ] Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20220307213356.2797205-46-brijesh.singh@amd.com
2022-04-07virt: sevguest: Add support to derive keyBrijesh Singh1-0/+45
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 chooses, such as a sealing key or communicating with the external entities. See SEV-SNP firmware spec for more information. [ bp: No need to memset "req" - it will get overwritten. ] Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Liam Merwick <liam.merwick@oracle.com> Link: https://lore.kernel.org/r/20220307213356.2797205-45-brijesh.singh@amd.com
2022-04-07virt: Add SEV-SNP guest driverBrijesh Singh4-0/+721
The 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 a struct snp_guest_platform_data descriptor. Userspace can use SNP_GET_REPORT ioctl() to query the guest attestation report. See SEV-SNP spec section Guest Messages for more details. [ bp: Remove the "what" from the commit message, massage. ] Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20220307213356.2797205-44-brijesh.singh@amd.com