This function is fine to use in other languages Reviewed-by: Ján Tomko <jtomko(a)redhat.com&gt; Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; --- build-aux/syntax-check.mk | 1 + 1 file changed, 1 insertion(+) diff --git a/build-aux/syntax-check.mk b/build-aux/syntax-check.mk index 68cd9dff5f..e1d80bd536 100644 --- a/build-aux/syntax-check.mk +++ b/build-aux/syntax-check.mk @@ -203,6 +203,7 @@ sc_prohibit_readlink: sc_prohibit_gethostname: @prohibit='gethostname *\(' \ + in_vc_files='\.[ch]$$' \ halt='use virGetHostname, not gethostname' \ $(_sc_search_regexp) -- 2.37.3

Accept information about a connection to libvirt and a guest on the command line. Talk to libvirt to obtain the running guest state and automatically detect as much configuration as possible. It will refuse to use a libvirt connection that is thought to be local to the current machine, as running this tool on the hypervisor itself is not considered secure. This can be overridden using the --insecure flag. When querying the guest, it will also analyse the XML configuration in an attempt to detect any options that are liable to be mistakes. For example the NVRAM being measured should not have a persistent varstore. Reviewed-by: Ján Tomko <jtomko(a)redhat.com&gt; Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; --- docs/manpages/virt-qemu-sev-validate.rst | 111 +++++++++++- tools/virt-qemu-sev-validate | 207 +++++++++++++++++++++-- 2 files changed, 304 insertions(+), 14 deletions(-) diff --git a/docs/manpages/virt-qemu-sev-validate.rst b/docs/manpages/virt-qemu-sev-validate.rst index 0f6c64ba90..e2c4672a05 100644 --- a/docs/manpages/virt-qemu-sev-validate.rst +++ b/docs/manpages/virt-qemu-sev-validate.rst @@ -37,6 +37,12 @@ another virtual machine protected by AMD SEV that has already had its launch measurement validated. Running this program on the virtualization host will not produce an answer that can be trusted. +If told to connect to libvirt, it will refuse to use a libvirt connection that +is local to the machine, since that cannot be trusted. For the sake of testing +or demonstration purposes, however, it can be forced to run in this scenario +using the ``--insecure`` flag. The result will, of course, still not be +trustworthy. + OPTIONS ======= @@ -115,6 +121,43 @@ size, with the first 16 bytes containing the TEK and the last 16 bytes containing the TIK. This is mutually exclusive with the ``--tik`` and ``--tek`` arguments. +Libvirt options +--------------- + +These options are used when connecting to libvirt to automatically obtain +state and configuration information about the domain to be attested. + +``-c``, ``--connect URI`` + +Libvirt connection URI. For the validation to be trustworthy this must be a URI +resolving to a remote virtualization host. This requirement can be overridden +using the ``--insecure`` argument. + +``-o``, ``--domain ID|NAME|UUID`` + +Domain ID, or domain name or domain UUID. Used to identify which libvirt domain +is to have its launch measured. The domain must be running, and would usually +have been started in a paused state, to allow validation to be performed before +guest CPUs begin execution. + +``-i``, ``--insecure`` + +Proceed even if usage scenario is known to be insecure. This allows the program +to connect to a local libvirt hypervisor and rely on file content from the +virtualization host. It also allows the validation to proceed even if the +virtual machine CPUs are not in the initial paused state. The result of the +validation must not be trusted. + +``-g``, ``--ignore-config`` + +Do not attempt to sanity check the domain config. The default behaviour is to +print out errors if identifying configuration elements in the guest XML that +would invalidate the launch measurement. This can help the guest owner to +understand any configuration mistakes that have been made. If the +``--ignore-config`` argument is given, this sanity checking of configuration +will be skipped. The result is that the validation will likely be reported as +failed. + EXAMPLES ======== @@ -139,6 +182,46 @@ Validate the measurement of a SEV guest booting from disk: --build-id 13 \ --policy 3 +Fetch from remote libvirt +------------------------- + +This scenario allows fetching certain data from a remote hypervisor via a +connection to libvirt. It will aid in debugging by analysing the guest +configuration and reporting anything that could invalidate the measurement +of the guest. This usage model is considered secure, because the limited +information obtained from the untrusted hypervisor cannot be used to change +the result. + +Validate the measurement of a SEV guest booting from disk: + +:: + + # virt-qemu-sev-validate \ + --connect qemu+ssh://root@some.remote.host/system \ + --firmware OVMF.sev.fd \ + --tk this-guest-tk.bin \ + --domain fedora34x86_64 + +Fetch from local libvirt +------------------------ + +This scenario allows fetching all data from the local hypervisor via a +connection to libvirt. It is only to be used for the purpose of testing, +debugging, or demonstrations, because running on the local hypervisor is not +a secure scenario. To enable this usage, the ``--insecure`` flag must be +specified. Given a pointer to the libvirt guest to validate, all information +needed to perform a validation, except the TIK/TEK pair can be acquired +automatically. + +Validate the measurement of a SEV guest booting from disk: + +:: + + # virt-qemu-sev-validate \ + --insecure \ + --tk this-guest-tk.bin \ + --domain fedora34x86_64 + EXIT STATUS =========== @@ -158,7 +241,33 @@ be set: The way in which this program has been invoked prevent it from being able to validate the launch measurement. -* **3** - *unexpected error occurred in the code* +* **3** - *Usage scenario is not secure* + + The way in which this program has been invoked means that the result of any + launch measurement validation will not be secure. + + The program can be reinvoked with ``--insecure`` argument to force a + validation, however, the results of this should not be trusted. This should + only be used for testing, debugging or demonstration purposes, never in a + production deployment. + +* **4** - *Domain has incorrect configuration to be measured* + + The way in which the guest has been configured prevent this program from being + able to validate the launch measurement. Note that in general the guest + configuration reported by the hypervisor is not trustworthy, so it is + possible this error could be a false positive designed to cause a denial of + service. + + This program can be reinvoked with the ``--ignore-config`` argument to skip + the sanity checks on the domain XML. This will likely result in it failing + with an exit code of **1** indicating the measurement is invalid + +* **5** - *Domain is in incorrect state to be measured* + + The domain has to be running in order to validate a launch measurement. + +* **6** - *unexpected error occurred in the code* A logic flaw in this program means it is unable to complete the validation of the measurement. This is a bug which should be reported to the maintainers. diff --git a/tools/virt-qemu-sev-validate b/tools/virt-qemu-sev-validate index 7ff54e7623..31c739c10f 100755 --- a/tools/virt-qemu-sev-validate +++ b/tools/virt-qemu-sev-validate @@ -39,9 +39,14 @@ from base64 import b64decode from hashlib import sha256 import hmac import logging +import re +import socket import sys import traceback +from lxml import etree +import libvirt + log = logging.getLogger() @@ -53,6 +58,18 @@ class UnsupportedUsageException(Exception): pass +class InsecureUsageException(Exception): + pass + + +class IncorrectConfigException(Exception): + pass + + +class InvalidStateException(Exception): + pass + + class ConfidentialVM(object): def __init__(self, @@ -159,6 +176,108 @@ class ConfidentialVM(object): "Measurement does not match, VM is not trustworthy") +class LibvirtConfidentialVM(ConfidentialVM): + def __init__(self, **kwargs): + super().__init__(**kwargs) + + self.conn = None + self.dom = None + + def check_domain(self, doc, secure): + ls = doc.xpath("/domain/launchSecurity[@type='sev']") + if len(ls) != 1: + raise IncorrectConfigException( + "Domain is not configured with SEV launch security") + + dh = doc.xpath("/domain/launchSecurity[@type='sev']/dhCert") + if len(dh) != 1: + raise IncorrectConfigException( + "Domain must have SEV owner cert to validate measurement") + + session = doc.xpath("/domain/launchSecurity[@type='sev']/session") + if len(session) != 1: + raise IncorrectConfigException( + "Domain must have SEV session data to validate measurement") + + nvramnodes = doc.xpath("/domain/os/nvram") + if len(nvramnodes) != 0 and secure: + raise InsecureUsageException( + "Domain firmware with NVRAM cannot be securely measured") + + loadernodes = doc.xpath("/domain/os/loader") + if len(loadernodes) != 1: + raise IncorrectConfigException( + "Domain must have one firmware path") + + def load_domain(self, uri, id_name_uuid, secure, ignore_config): + self.conn = libvirt.open(uri) + + remote = socket.gethostname() != self.conn.getHostname() + if not remote and secure: + raise InsecureUsageException( + "running locally on the hypervisor host is not secure") + + if re.match(r'^\d+$', id_name_uuid): + self.dom = self.conn.lookupByID(int(id_name_uuid)) + elif re.match(r'^[-a-f0-9]+$', id_name_uuid): + self.dom = self.conn.lookupByUUIDString(id_name_uuid) + else: + self.dom = self.conn.lookupByName(id_name_uuid) + + log.debug("VM: id=%d name=%s uuid=%s", + self.dom.ID(), self.dom.name(), self.dom.UUIDString()) + + if not self.dom.isActive(): + raise InvalidStateException( + "Domain must be running to validate measurement") + + state = self.dom.info()[0] + if state != libvirt.VIR_DOMAIN_PAUSED and secure: + raise InvalidStateException( + "Domain must be paused to validate measurement") + + xml = self.dom.XMLDesc() + + doc = etree.fromstring(xml) + if not ignore_config: + self.check_domain(doc, secure) + + # See comments at top of file wrt why we are OK to trust the + # sev-api-major, sev-api-minor, sev-build-id and sev-policy data + # reported by the host + sevinfo = self.dom.launchSecurityInfo() + + if "sev-api-major" not in sevinfo: + raise UnsupportedUsageException( + "'api-major' not reported in domain launch security info") + + if self.measurement is None: + self.measurement = sevinfo["sev-measurement"] + if self.api_major is None: + self.api_major = sevinfo["sev-api-major"] + if self.api_minor is None: + self.api_minor = sevinfo["sev-api-minor"] + if self.build_id is None: + self.build_id = sevinfo["sev-build-id"] + if self.policy is None: + self.policy = sevinfo["sev-policy"] + + if self.firmware is None: + if remote: + raise UnsupportedUsageException( + "Cannot access firmware path remotely") + if secure: + raise InsecureUsageException( + "Using firmware path from XML is not secure") + + loadernodes = doc.xpath("/domain/os/loader") + if len(loadernodes) == 0: + raise UnsupportedUsageException( + "--firmware not specified and no firmware path found") + + self.load_firmware(loadernodes[0].text) + + def parse_command_line(): parser = argparse.ArgumentParser( description='Validate guest AMD SEV launch measurement') @@ -169,20 +288,20 @@ def parse_command_line(): # Arguments related to the state of the launched guest vmstate = parser.add_argument_group("Virtual machine launch state") - vmstate.add_argument('--measurement', '-m', required=True, + vmstate.add_argument('--measurement', '-m', help='Measurement for the running domain') - vmstate.add_argument('--api-major', type=int, required=True, + vmstate.add_argument('--api-major', type=int, help='SEV API major version for the running domain') - vmstate.add_argument('--api-minor', type=int, required=True, + vmstate.add_argument('--api-minor', type=int, help='SEV API minor version for the running domain') - vmstate.add_argument('--build-id', type=int, required=True, + vmstate.add_argument('--build-id', type=int, help='SEV build ID for the running domain') - vmstate.add_argument('--policy', type=int, required=True, + vmstate.add_argument('--policy', type=int, help='SEV policy for the running domain') # Arguments related to calculation of the expected launch measurement vmconfig = parser.add_argument_group("Virtual machine config") - vmconfig.add_argument('--firmware', '-f', required=True, + vmconfig.add_argument('--firmware', '-f', help='Path to the firmware binary') vmconfig.add_argument('--tik', help='TIK file for domain') @@ -191,6 +310,17 @@ def parse_command_line(): vmconfig.add_argument('--tk', help='TEK/TIK combined file for domain') + # Arguments related to the connection to libvirt + vmconn = parser.add_argument_group("Libvirt guest connection") + vmconn.add_argument('--connect', '-c', default="qemu:///system", + help='libvirt connection URI') + vmconn.add_argument('--domain', '-o', + help='domain ID / Name / UUID') + vmconn.add_argument('--insecure', '-i', action='store_true', + help='Proceed even if usage scenario is insecure') + vmconn.add_argument('--ignore-config', '-g', action='store_true', + help='Do not attempt to sanity check the guest config') + return parser.parse_args() @@ -206,21 +336,60 @@ def check_usage(args): raise UnsupportedUsageException( "Either --tk or both of --tek/--tik are required") + if args.domain is None: + if args.measurement is None: + raise UnsupportedUsageException( + "Either --measurement or --domain is required") + + if args.api_major is None: + raise UnsupportedUsageException( + "Either --api-major or --domain is required") + + if args.api_minor is None: + raise UnsupportedUsageException( + "Either --api-minor or --domain is required") + + if args.build_id is None: + raise UnsupportedUsageException( + "Either --build-id or --domain is required") + + if args.policy is None: + raise UnsupportedUsageException( + "Either --policy or --domain is required") + + if args.firmware is None: + raise UnsupportedUsageException( + "Either --firmware or --domain is required") + def attest(args): - cvm = ConfidentialVM(measurement=args.measurement, - api_major=args.api_major, - api_minor=args.api_minor, - build_id=args.build_id, - policy=args.policy) + if args.domain is None: + cvm = ConfidentialVM(measurement=args.measurement, + api_major=args.api_major, + api_minor=args.api_minor, + build_id=args.build_id, + policy=args.policy) + else: + cvm = LibvirtConfidentialVM(measurement=args.measurement, + api_major=args.api_major, + api_minor=args.api_minor, + build_id=args.build_id, + policy=args.policy) - cvm.load_firmware(args.firmware) + if args.firmware is not None: + cvm.load_firmware(args.firmware) if args.tk is not None: cvm.load_tk(args.tk) else: cvm.load_tik_tek(args.tik, args.tek) + if args.domain is not None: + cvm.load_domain(args.connect, + args.domain, + not args.insecure, + args.ignore_config) + cvm.attest() if not args.quiet: @@ -252,12 +421,24 @@ def main(): if not args.quiet: print("ERROR: %s" % e, file=sys.stderr) sys.exit(2) + except InsecureUsageException as e: + if not args.quiet: + print("ERROR: %s" % e, file=sys.stderr) + sys.exit(3) + except IncorrectConfigException as e: + if not args.quiet: + print("ERROR: %s" % e, file=sys.stderr) + sys.exit(4) + except InvalidStateException as e: + if not args.quiet: + print("ERROR: %s" % e, file=sys.stderr) + sys.exit(5) except Exception as e: if args.debug: traceback.print_tb(e.__traceback__) if not args.quiet: print("ERROR: %s" % e, file=sys.stderr) - sys.exit(3) + sys.exit(6) if __name__ == "__main__": main() -- 2.37.3

When connected to libvirt we can validate that the guest configuration has the kernel hashes property enabled, otherwise including the kernel GUID table in our expected measurements is not likely to match the actual measurement. When running locally we can also automatically detect the kernel/initrd paths, along with the cmdline string from the XML. Reviewed-by: Ján Tomko <jtomko(a)redhat.com&gt; Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; --- docs/manpages/virt-qemu-sev-validate.rst | 9 ++++ tools/virt-qemu-sev-validate | 59 ++++++++++++++++++++++++ 2 files changed, 68 insertions(+) diff --git a/docs/manpages/virt-qemu-sev-validate.rst b/docs/manpages/virt-qemu-sev-validate.rst index e8a868f5a8..e374fecec0 100644 --- a/docs/manpages/virt-qemu-sev-validate.rst +++ b/docs/manpages/virt-qemu-sev-validate.rst @@ -265,6 +265,15 @@ Validate the measurement of a SEV guest booting from disk: --tk this-guest-tk.bin \ --domain fedora34x86_64 +Validate the measurement of a SEV guest with direct kernel boot: + +:: + + # virt-dom-sev-validate \ + --insecure \ + --tk this-guest-tk.bin \ + --domain fedora34x86_64 + EXIT STATUS =========== diff --git a/tools/virt-qemu-sev-validate b/tools/virt-qemu-sev-validate index b978c3eb3d..301660ba8e 100755 --- a/tools/virt-qemu-sev-validate +++ b/tools/virt-qemu-sev-validate @@ -300,6 +300,35 @@ class LibvirtConfidentialVM(ConfidentialVM): raise IncorrectConfigException( "Domain must have one firmware path") + measure_kernel_nodes = doc.xpath( + "/domain/launchSecurity[@type='sev']/@kernelHashes") + measure_kernel = False + if len(measure_kernel_nodes) == 1: + if measure_kernel_nodes[0] == "yes": + measure_kernel = True + + xp_kernel = "/domain/os/kernel" + xp_initrd = "/domain/os/initrd" + xp_cmdline = "/domain/os/cmdline" + kern_nodes = (doc.xpath(xp_kernel) + + doc.xpath(xp_initrd) + + doc.xpath(xp_cmdline)) + if not measure_kernel: + if len(self.kernel_table.entries()) != 0: + raise UnsupportedUsageException( + "kernel/initrd/cmdline provided but kernel " + "measurement not enabled") + + # Check for an insecure scenario + if len(kern_nodes) != 0 and secure: + raise InsecureUsageException( + "direct kernel boot present without measurement") + else: + if len(kern_nodes) == 0: + raise IncorrectConfigException( + "kernel/initrd/cmdline not provided but kernel " + "measurement is enabled") + def load_domain(self, uri, id_name_uuid, secure, ignore_config): self.conn = libvirt.open(uri) @@ -368,6 +397,36 @@ class LibvirtConfidentialVM(ConfidentialVM): self.load_firmware(loadernodes[0].text) + if self.kernel_table.kernel is None: + kernelnodes = doc.xpath("/domain/os/kernel") + if len(kernelnodes) != 0: + if remote: + raise UnsupportedUsageException( + "Cannot access kernel path remotely") + if secure: + raise InsecureUsageException( + "Using kernel path from XML is not secure") + self.kernel_table.load_kernel(kernelnodes[0].text) + + if self.kernel_table.initrd is None: + initrdnodes = doc.xpath("/domain/os/initrd") + if len(initrdnodes) != 0: + if remote: + raise UnsupportedUsageException( + "Cannot access initrd path remotely") + if secure: + raise InsecureUsageException( + "Using initrd path from XML is not secure") + self.kernel_table.load_initrd(initrdnodes[0].text) + + if self.kernel_table.cmdline is None: + cmdlinenodes = doc.xpath("/domain/os/cmdline") + if len(cmdlinenodes) != 0: + if secure: + raise InsecureUsageException( + "Using cmdline string from XML is not secure") + self.kernel_table.load_cmdline(cmdlinenodes[0].text) + def parse_command_line(): parser = argparse.ArgumentParser( -- 2.37.3

The VMSA files contain the expected CPU register state for the VM. Their content varies based on a few pieces of the stack - AMD CPU architectural initial state - KVM hypervisor VM CPU initialization - QEMU userspace VM CPU initialization - AMD CPU SKU (family/model/stepping) The first three pieces of information we can obtain through code inspection. The last piece of information we can take on the command line. This allows a user to validate a SEV-ES guest merely by providing the CPU SKU information, using --cpu-family, --cpu-model, --cpu-stepping. This avoids the need to obtain or construct VMSA files directly. Reviewed-by: Ján Tomko <jtomko(a)redhat.com&gt; Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; --- docs/manpages/virt-qemu-sev-validate.rst | 45 +++ tools/virt-qemu-sev-validate | 467 +++++++++++++++++++++++ 2 files changed, 512 insertions(+) diff --git a/docs/manpages/virt-qemu-sev-validate.rst b/docs/manpages/virt-qemu-sev-validate.rst index d51969d0b2..34ef328fe8 100644 --- a/docs/manpages/virt-qemu-sev-validate.rst +++ b/docs/manpages/virt-qemu-sev-validate.rst @@ -245,6 +245,24 @@ Validate the measurement of a SEV-ES SMP guest booting from disk: --build-id 13 \ --policy 7 +Validate the measurement of a SEV-ES SMP guest booting from disk, with +automatically constructed VMSA: + +:: + + # virt-dom-sev-validate \ + --firmware OVMF.sev.fd \ + --num-cpus 2 \ + --cpu-family 23 \ + --cpu-model 49 \ + --cpu-stepping 0 \ + --tk this-guest-tk.bin \ + --measurement Zs2pf19ubFSafpZ2WKkwquXvACx9Wt/BV+eJwQ/taO8jhyIj/F8swFrybR1fZ2ID \ + --api-major 0 \ + --api-minor 24 \ + --build-id 13 \ + --policy 7 + Fetch from remote libvirt ------------------------- @@ -291,6 +309,20 @@ Validate the measurement of a SEV-ES SMP guest booting from disk: --tk this-guest-tk.bin \ --domain fedora34x86_64 +Validate the measurement of a SEV-ES SMP guest booting from disk, with +automatically constructed VMSA: + +:: + + # virt-dom-sev-validate \ + --connect qemu+ssh://root@some.remote.host/system \ + --firmware OVMF.sev.fd \ + --cpu-family 23 \ + --cpu-model 49 \ + --cpu-stepping 0 \ + --tk this-guest-tk.bin \ + --domain fedora34x86_64 + Fetch from local libvirt ------------------------ @@ -332,6 +364,19 @@ Validate the measurement of a SEV-ES SMP guest booting from disk: --tk this-guest-tk.bin \ --domain fedora34x86_64 +Validate the measurement of a SEV-ES SMP guest booting from disk, with +automatically constructed VMSA: + +:: + + # virt-dom-sev-validate \ + --insecure \ + --cpu-family 23 \ + --cpu-model 49 \ + --cpu-stepping 0 \ + --tk this-guest-tk.bin \ + --domain fedora34x86_64 + EXIT STATUS =========== diff --git a/tools/virt-qemu-sev-validate b/tools/virt-qemu-sev-validate index 6003ba2929..ef8fa6fa27 100755 --- a/tools/virt-qemu-sev-validate +++ b/tools/virt-qemu-sev-validate @@ -42,6 +42,7 @@ import hmac import logging import re import socket +from struct import pack import sys import traceback from uuid import UUID @@ -72,6 +73,427 @@ class InvalidStateException(Exception): pass +class Field(object): + U8 = 0 + U16 = 2 + U32 = 4 + U64 = 8 + + SCALAR = 0 + BITMASK = 1 + ARRAY = 2 + + def __init__(self, name, size, fmt, value, order): + self.name = name + self.size = size + self.value = value + self.fmt = fmt + self.order = order + + +class Struct(object): + def __init__(self, size): + self._fields = {} + self.size = size + + def register_field(self, name, size, fmt=Field.SCALAR, defvalue=0): + self._fields[name] = Field(name, size, fmt, + defvalue, len(self.fields)) + + @property + def fields(self): + return sorted(self._fields.values(), key=lambda f: f.order) + + def __getattr__(self, name): + return self._fields[name] + + def __setattr__(self, name, value): + if name in ["_fields", "size"]: + super().__setattr__(name, value) + else: + self._fields[name].value = value + + def binary_format(self): + fmt = ["<"] + datalen = 0 + for field in self.fields: + if field.size == Field.U8: + if field.fmt == Field.ARRAY: + datalen += len(field.value) + fmt += ["%dB" % len(field.value)] + else: + datalen += 1 + fmt += ["B"] + elif field.size == Field.U16: + datalen += 2 + fmt += ["H"] + elif field.size == Field.U32: + datalen += 4 + fmt += ["L"] + elif field.size == Field.U64: + datalen += 8 + fmt += ["Q"] + + pad = self.size - datalen + assert self.size >= 1 + fmt += ["%dB" % pad] + + return "".join(fmt), pad + + def pack(self): + fmt, pad = self.binary_format() + + values = [] + for field in self.fields: + if field.size == Field.U8 and field.fmt == Field.ARRAY: + for _, k in enumerate(field.value): + values.append(k) + else: + values.append(field.value) + values.extend([0] * pad) + + return pack(fmt, *values) + + +class VMSA(Struct): + ATTR_G_SHIFT = 23 + ATTR_G_MASK = (1 << ATTR_G_SHIFT) + ATTR_B_SHIFT = 22 + ATTR_B_MASK = (1 << ATTR_B_SHIFT) + ATTR_L_SHIFT = 21 + ATTR_L_MASK = (1 << ATTR_L_SHIFT) + ATTR_AVL_SHIFT = 20 + ATTR_AVL_MASK = (1 << ATTR_AVL_SHIFT) + ATTR_P_SHIFT = 15 + ATTR_P_MASK = (1 << ATTR_P_SHIFT) + ATTR_DPL_SHIFT = 13 + ATTR_DPL_MASK = (3 << ATTR_DPL_SHIFT) + ATTR_S_SHIFT = 12 + ATTR_S_MASK = (1 << ATTR_S_SHIFT) + ATTR_TYPE_SHIFT = 8 + ATTR_TYPE_MASK = (15 << ATTR_TYPE_SHIFT) + ATTR_A_MASK = (1 << 8) + + ATTR_CS_MASK = (1 << 11) + ATTR_C_MASK = (1 << 10) + ATTR_R_MASK = (1 << 9) + + ATTR_E_MASK = (1 << 10) + ATTR_W_MASK = (1 << 9) + + def __init__(self): + super().__init__(4096) + + # From Linux arch/x86/include/asm/svm.h, we're unpacking the + # struct vmcb_save_area + + self.register_field("es_selector", Field.U16) + self.register_field("es_attrib", Field.U16, Field.BITMASK) + self.register_field("es_limit", Field.U32) + self.register_field("es_base", Field.U64) + + self.register_field("cs_selector", Field.U16) + self.register_field("cs_attrib", Field.U16, Field.BITMASK) + self.register_field("cs_limit", Field.U32) + self.register_field("cs_base", Field.U64) + + self.register_field("ss_selector", Field.U16) + self.register_field("ss_attrib", Field.U16, Field.BITMASK) + self.register_field("ss_limit", Field.U32) + self.register_field("ss_base", Field.U64) + + self.register_field("ds_selector", Field.U16) + self.register_field("ds_attrib", Field.U16, Field.BITMASK) + self.register_field("ds_limit", Field.U32) + self.register_field("ds_base", Field.U64) + + self.register_field("fs_selector", Field.U16) + self.register_field("fs_attrib", Field.U16, Field.BITMASK) + self.register_field("fs_limit", Field.U32) + self.register_field("fs_base", Field.U64) + + self.register_field("gs_selector", Field.U16) + self.register_field("gs_attrib", Field.U16, Field.BITMASK) + self.register_field("gs_limit", Field.U32) + self.register_field("gs_base", Field.U64) + + self.register_field("gdtr_selector", Field.U16) + self.register_field("gdtr_attrib", Field.U16, Field.BITMASK) + self.register_field("gdtr_limit", Field.U32) + self.register_field("gdtr_base", Field.U64) + + self.register_field("ldtr_selector", Field.U16) + self.register_field("ldtr_attrib", Field.U16, Field.BITMASK) + self.register_field("ldtr_limit", Field.U32) + self.register_field("ldtr_base", Field.U64) + + self.register_field("idtr_selector", Field.U16) + self.register_field("idtr_attrib", Field.U16, Field.BITMASK) + self.register_field("idtr_limit", Field.U32) + self.register_field("idtr_base", Field.U64) + + self.register_field("tr_selector", Field.U16) + self.register_field("tr_attrib", Field.U16, Field.BITMASK) + self.register_field("tr_limit", Field.U32) + self.register_field("tr_base", Field.U64) + + self.register_field("reserved_1", + Field.U8, Field.ARRAY, bytearray([0] * 43)) + + self.register_field("cpl", Field.U8) + + self.register_field("reserved_2", + Field.U8, Field.ARRAY, bytearray([0] * 4)) + + self.register_field("efer", Field.U64) + + self.register_field("reserved_3", + Field.U8, Field.ARRAY, bytearray([0] * 104)) + + self.register_field("xss", Field.U64) + self.register_field("cr4", Field.U64) + self.register_field("cr3", Field.U64) + self.register_field("cr0", Field.U64) + self.register_field("dr7", Field.U64) + self.register_field("dr6", Field.U64) + self.register_field("rflags", Field.U64) + self.register_field("rip", Field.U64) + + self.register_field("reserved_4", + Field.U8, Field.ARRAY, bytearray([0] * 88)) + + self.register_field("rsp", Field.U64) + + self.register_field("reserved_5", + Field.U8, Field.ARRAY, bytearray([0] * 24)) + + self.register_field("rax", Field.U64) + self.register_field("star", Field.U64) + self.register_field("lstar", Field.U64) + self.register_field("cstar", Field.U64) + self.register_field("sfmask", Field.U64) + self.register_field("kernel_gs_base", Field.U64) + self.register_field("sysenter_cs", Field.U64) + self.register_field("sysenter_esp", Field.U64) + self.register_field("sysenter_eip", Field.U64) + self.register_field("cr2", Field.U64) + + self.register_field("reserved_6", + Field.U8, Field.ARRAY, bytearray([0] * 32)) + + self.register_field("g_pat", Field.U64) + self.register_field("dbgctl", Field.U64) + self.register_field("br_from", Field.U64) + self.register_field("br_to", Field.U64) + self.register_field("last_excp_from", Field.U64) + self.register_field("last_excp_to", Field.U64) + + self.register_field("reserved_7", + Field.U8, Field.ARRAY, bytearray([0] * 72)) + + self.register_field("spec_ctrl", Field.U32) + + self.register_field("reserved_7b", + Field.U8, Field.ARRAY, bytearray([0] * 4)) + + self.register_field("pkru", Field.U32) + + self.register_field("reserved_7a", + Field.U8, Field.ARRAY, bytearray([0] * 20)) + + self.register_field("reserved_8", Field.U64) # rax duplicate + + self.register_field("rcx", Field.U64) + self.register_field("rdx", Field.U64, Field.BITMASK) + self.register_field("rbx", Field.U64) + + self.register_field("reserved_9", Field.U64) # rsp duplicate + + self.register_field("rbp", Field.U64) + self.register_field("rsi", Field.U64) + self.register_field("rdi", Field.U64) + self.register_field("r8", Field.U64) + self.register_field("r9", Field.U64) + self.register_field("r10", Field.U64) + self.register_field("r11", Field.U64) + self.register_field("r12", Field.U64) + self.register_field("r13", Field.U64) + self.register_field("r14", Field.U64) + self.register_field("r15", Field.U64) + + self.register_field("reserved_10", + Field.U8, Field.ARRAY, bytearray([0] * 16)) + + self.register_field("sw_exit_code", Field.U64) + self.register_field("sw_exit_info_1", Field.U64) + self.register_field("sw_exit_info_2", Field.U64) + self.register_field("sw_scratch", Field.U64) + + self.register_field("reserved_11", + Field.U8, Field.ARRAY, bytearray([0] * 56)) + + self.register_field("xcr0", Field.U64) + self.register_field("valid_bitmap", + Field.U8, Field.ARRAY, bytearray([0] * 16)) + self.register_field("x87_state_gpa", + Field.U64) + + def amd64_cpu_init(self): + # AMD64 Architecture Programmer’s Manual + # Volume 2: System Programming. + # + # 14.1.3 Processor Initialization State + # + # Values after INIT + + self.cr0 = (1 << 4) + self.rip = 0xfff0 + + self.cs_selector = 0xf000 + self.cs_base = 0xffff0000 + self.cs_limit = 0xffff + + self.ds_limit = 0xffff + + self.es_limit = 0xffff + self.fs_limit = 0xffff + self.gs_limit = 0xffff + self.ss_limit = 0xffff + + self.gdtr_limit = 0xffff + self.idtr_limit = 0xffff + + self.ldtr_limit = 0xffff + self.tr_limit = 0xffff + + self.dr6 = 0xffff0ff0 + self.dr7 = 0x0400 + self.rflags = 0x2 + self.xcr0 = 0x1 + + def kvm_cpu_init(self): + # svm_set_cr4() sets guest X86_CR4_MCE bit if host + # has X86_CR4_MCE enabled + self.cr4 = 0x40 + + # svm_set_efer sets guest EFER_SVME (Secure Virtual Machine enable) + self.efer = 0x1000 + + # init_vmcb + init_sys_seg() sets + # SVM_SELECTOR_P_MASK | SEG_TYPE_LDT + self.ldtr_attrib = 0x0082 + + # init_vmcb + init_sys_seg() sets + # SVM_SELECTOR_P_MASK | SEG_TYPE_BUSY_TSS16 + self.tr_attrib = 0x0083 + + # kvm_arch_vcpu_create() in arch/x86/kvm/x86.c + self.g_pat = 0x0007040600070406 + + def qemu_cpu_init(self): + # Based on logic in x86_cpu_reset() + # + # file target/i386/cpu.c + + def attr(mask): + return (mask >> VMSA.ATTR_TYPE_SHIFT) + + self.ldtr_attrib = attr(VMSA.ATTR_P_MASK | + (2 << VMSA.ATTR_TYPE_SHIFT)) + self.tr_attrib = attr(VMSA.ATTR_P_MASK | + (11 << VMSA.ATTR_TYPE_SHIFT)) + self.cs_attrib = attr(VMSA.ATTR_P_MASK | + VMSA.ATTR_S_MASK | + VMSA.ATTR_CS_MASK | + VMSA.ATTR_R_MASK | + VMSA.ATTR_A_MASK) + self.ds_attrib = attr(VMSA.ATTR_P_MASK | + VMSA.ATTR_S_MASK | + VMSA.ATTR_W_MASK | + VMSA.ATTR_A_MASK) + self.es_attrib = attr(VMSA.ATTR_P_MASK | + VMSA.ATTR_S_MASK | + VMSA.ATTR_W_MASK | + VMSA.ATTR_A_MASK) + self.ss_attrib = attr(VMSA.ATTR_P_MASK | + VMSA.ATTR_S_MASK | + VMSA.ATTR_W_MASK | + VMSA.ATTR_A_MASK) + self.fs_attrib = attr(VMSA.ATTR_P_MASK | + VMSA.ATTR_S_MASK | + VMSA.ATTR_W_MASK | + VMSA.ATTR_A_MASK) + self.gs_attrib = attr(VMSA.ATTR_P_MASK | + VMSA.ATTR_S_MASK | + VMSA.ATTR_W_MASK | + VMSA.ATTR_A_MASK) + + self.g_pat = 0x0007040600070406 + + def cpu_sku(self, family, model, stepping): + stepping &= 0xf + model &= 0xff + family &= 0xfff + + self.rdx.value = stepping + + if family > 0xf: + self.rdx.value |= 0xf00 | ((family - 0x0f) << 20) + else: + self.rdx.value |= family << 8 + + self.rdx.value |= ((model & 0xf) << 4) | ((model >> 4) << 16) + + def reset_addr(self, reset_addr): + reset_cs = reset_addr & 0xffff0000 + reset_ip = reset_addr & 0x0000ffff + + self.rip.value = reset_ip + self.cs_base.value = reset_cs + + +class OVMF(object): + + OVMF_TABLE_FOOTER_GUID = UUID("96b582de-1fb2-45f7-baea-a366c55a082d") + SEV_INFO_BLOCK_GUID = UUID("00f771de-1a7e-4fcb-890e-68c77e2fb44e") + + def __init__(self): + self.entries = {} + + def load(self, content): + expect = OVMF.OVMF_TABLE_FOOTER_GUID.bytes_le + actual = content[-48:-32] + if expect != actual: + raise Exception("OVMF footer GUID not found") + + tablelen = int.from_bytes(content[-50:-48], byteorder='little') + + if tablelen == 0: + raise Exception("OVMF tables zero length") + + table = content[-(32 + tablelen):-50] + + self.parse_table(table) + + def parse_table(self, data): + while len(data) > 0: + entryuuid = UUID(bytes_le=data[-16:]) + entrylen = int.from_bytes(data[-18:-16], byteorder='little') + entrydata = data[-entrylen:-18] + + self.entries[str(entryuuid)] = entrydata + + data = data[0:-entrylen] + + def reset_addr(self): + if str(OVMF.SEV_INFO_BLOCK_GUID) not in self.entries: + raise Exception("SEV info block GUID not found") + + reset_addr = int.from_bytes( + self.entries[str(OVMF.SEV_INFO_BLOCK_GUID)], "little") + return reset_addr + + class GUIDTable(abc.ABC): GUID_LEN = 16 @@ -242,6 +664,26 @@ class ConfidentialVM(object): log.debug("VMSA CPU 1(sha256): %s", sha256(self.vmsa_cpu1).hexdigest()) + def build_vmsas(self, family, model, stepping): + ovmf = OVMF() + ovmf.load(self.firmware) + + vmsa = VMSA() + vmsa.amd64_cpu_init() + vmsa.kvm_cpu_init() + vmsa.qemu_cpu_init() + + vmsa.cpu_sku(family, model, stepping) + + self.vmsa_cpu0 = vmsa.pack() + log.debug("VMSA CPU 0(sha256): %s", + sha256(self.vmsa_cpu0).hexdigest()) + + vmsa.reset_addr(ovmf.reset_addr()) + self.vmsa_cpu1 = vmsa.pack() + log.debug("VMSA CPU 1(sha256): %s", + sha256(self.vmsa_cpu1).hexdigest()) + def get_cpu_state(self): if self.num_cpus is None: raise UnsupportedUsageException( @@ -514,6 +956,12 @@ def parse_command_line(): help='VMSA state for the boot CPU') vmconfig.add_argument('--vmsa-cpu1', '-1', help='VMSA state for the additional CPUs') + vmconfig.add_argument('--cpu-family', type=int, + help='Hypervisor host CPU family number') + vmconfig.add_argument('--cpu-model', type=int, + help='Hypervisor host CPU model number') + vmconfig.add_argument('--cpu-stepping', type=int, + help='Hypervisor host CPU stepping number') vmconfig.add_argument('--tik', help='TIK file for domain') vmconfig.add_argument('--tek', @@ -577,6 +1025,20 @@ def check_usage(args): raise UnsupportedUsageException( "--initrd/--cmdline require --kernel") + sku = [args.cpu_family, args.cpu_model, args.cpu_stepping] + if sku.count(None) == len(sku): + if args.vmsa_cpu1 is not None and args.vmsa_cpu0 is None: + raise UnsupportedUsageException( + "VMSA for additional CPU also requires VMSA for boot CPU") + else: + if args.vmsa_cpu0 is not None or args.vmsa_cpu1 is not None: + raise UnsupportedUsageException( + "VMSA files are mutually exclusive with CPU SKU") + + if sku.count(None) != 0: + raise UnsupportedUsageException( + "CPU SKU needs family, model and stepping for SEV-ES domain") + def attest(args): if args.domain is None: @@ -617,6 +1079,11 @@ def attest(args): if args.vmsa_cpu1 is not None: cvm.load_vmsa_cpu1(args.vmsa_cpu1) + if args.cpu_family is not None: + cvm.build_vmsas(args.cpu_family, + args.cpu_model, + args.cpu_stepping) + if args.domain is not None: cvm.load_domain(args.connect, args.domain, -- 2.37.3

It is possible to build OVMF for SEV with an embedded Grub that can fetch LUKS disk secrets. This adds support for injecting secrets in the required format. Reviewed-by: Ján Tomko <jtomko(a)redhat.com&gt; Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; --- docs/manpages/virt-qemu-sev-validate.rst | 83 ++++++++++ tools/virt-qemu-sev-validate | 183 +++++++++++++++++++++-- 2 files changed, 257 insertions(+), 9 deletions(-) diff --git a/docs/manpages/virt-qemu-sev-validate.rst b/docs/manpages/virt-qemu-sev-validate.rst index eef8a0281c..24cdbb6d92 100644 --- a/docs/manpages/virt-qemu-sev-validate.rst +++ b/docs/manpages/virt-qemu-sev-validate.rst @@ -189,6 +189,46 @@ understand any configuration mistakes that have been made. If the will be skipped. The result is that the validation will likely be reported as failed. +Secret injection options +------------------------ + +These options provide a way to inject a secret if validation of the +launch measurement passes. + +``--inject-secret ALIAS-OR-GUID:PATH`` + +Path to a file containing a secret to inject into the guest OS. Typical +usage would be to supply a password for unlocking the root filesystem +full disk encryption. ``ALIAS`` can be one of the well known secrets: + +* ``luks-key`` - bytes to use as a key for unlocking a LUKS key slot. + GUID of ``736869e5-84f0-4973-92ec-06879ce3da0b``. + +Alternatively ``GUID`` refers to an arbitrary UUID of the callers +choosing. The contents of ``PATH`` are defined by the requirements +of the associated GUID, and will used as-is without modification. +In particular be aware: + + * Avoid unwanted trailing newline characters in ``PATH`` unless + mandated by the ``GUID``. + * Any trailing ``NUL`` byte must be explicitly included in ``PATH`` + if mandated by the ``GUID``. + +This argument can be repeated multiple times, provided a different +``GUID`` is given for each instance. + +``--secret-header PATH`` + +Path to a file in which the injected secret header will be written in base64 +format and later injected into the domain. This is required if there is no +connection to libvirt, otherwise the secret will be directly injected. + +``--secret-payload PATH`` + +Path to a file in which the injected secret payload will be written in base64 +format and later injected into the domain. This is required if there is no +connection to libvirt, otherwise the secret will be directly injected. + EXAMPLES ======== @@ -263,6 +303,26 @@ automatically constructed VMSA: --build-id 13 \ --policy 7 +Validate the measurement of a SEV guest booting from disk and +inject a disk password on success: + +:: + + # virt-dom-sev-validate \ + --loader OVMF.sev.fd \ + --tk this-guest-tk.bin \ + --measurement Zs2pf19ubFSafpZ2WKkwquXvACx9Wt/BV+eJwQ/taO8jhyIj/F8swFrybR1fZ2ID \ + --api-major 0 \ + --api-minor 24 \ + --build-id 13 \ + --policy 3 \ + --disk-password passwd.txt \ + --secret-header secret-header.b64 \ + --secret-payload secret-payload.b64 + +The ``secret-header.b64`` and ``secret-payload.b64`` files can now be sent to +the virtualization host for injection. + Fetch from remote libvirt ------------------------- @@ -323,6 +383,18 @@ automatically constructed VMSA: --tk this-guest-tk.bin \ --domain fedora34x86_64 +Validate the measurement of a SEV guest booting from disk and +inject a disk password on success: + +:: + + # virt-dom-sev-validate \ + --connect qemu+ssh://root@some.remote.host/system \ + --loader OVMF.sev.fd \ + --tk this-guest-tk.bin \ + --domain fedora34x86_64 \ + --disk-password passwd.txt + Fetch from local libvirt ------------------------ @@ -373,6 +445,17 @@ automatically constructed VMSA: --tk this-guest-tk.bin \ --domain fedora34x86_64 +Validate the measurement of a SEV guest booting from disk and +inject a disk password on success: + +:: + + # virt-dom-sev-validate \ + --insecure \ + --tk this-guest-tk.bin \ + --domain fedora34x86_64 \ + --disk-password passwd.txt + EXIT STATUS =========== diff --git a/tools/virt-qemu-sev-validate b/tools/virt-qemu-sev-validate index 37f6f65bac..712a4e4593 100755 --- a/tools/virt-qemu-sev-validate +++ b/tools/virt-qemu-sev-validate @@ -36,16 +36,19 @@ import abc import argparse -from base64 import b64decode +from base64 import b64decode, b64encode from hashlib import sha256 import hmac import logging +import os import re import socket from struct import pack import sys import traceback from uuid import UUID +from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes + from lxml import etree import libvirt @@ -579,7 +582,46 @@ class KernelTable(GUIDTable): return entries -class ConfidentialVM(object): +class SecretsTable(GUIDTable): + + TABLE_GUID = UUID('{1e74f542-71dd-4d66-963e-ef4287ff173b}').bytes_le + + GUID_ALIASES = { + "luks-key": UUID('{736869e5-84f0-4973-92ec-06879ce3da0b}') + } + + def __init__(self): + super().__init__(guid=self.TABLE_GUID, + lenlen=4) + self.secrets = {} + + def load_secret(self, alias_or_guid, path): + guid = None + if re.match(r"^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}$", + alias_or_guid): + guid = UUID(alias_or_guid) + else: + if alias_or_guid not in self.GUID_ALIASES: + raise UnsupportedUsageException( + "Secret alias '%s' is not known" % alias_or_guid) + + guid = self.GUID_ALIASES[alias_or_guid] + + if guid in self.secrets: + raise UnsupportedUsageException( + "Secret for GUID %s already loaded" % guid) + + with open(path, 'rb') as fh: + self.secrets[guid] = fh.read() + + def entries(self): + entries = bytes([]) + for guid, value in self.secrets.items(): + entries += self.build_entry(guid.bytes_le, value, 4) + return entries + + +class ConfidentialVM(abc.ABC): POLICY_BIT_SEV_ES = 2 POLICY_VAL_SEV_ES = (1 << POLICY_BIT_SEV_ES) @@ -605,6 +647,7 @@ class ConfidentialVM(object): self.vmsa_cpu1 = None self.kernel_table = KernelTable() + self.secrets_table = SecretsTable() def is_sev_es(self): return self.policy & self.POLICY_VAL_SEV_ES @@ -757,6 +800,82 @@ class ConfidentialVM(object): raise AttestationFailedException( "Measurement does not match, VM is not trustworthy") + def build_secrets(self): + measurement, _ = self.get_measurements() + + iv = os.urandom(16) + + secret_table = self.secrets_table.build() + + cipher = Cipher(algorithms.AES(self.tek), modes.CTR(iv)) + enc = cipher.encryptor() + secret_table_ciphertext = (enc.update(secret_table) + + enc.finalize()) + + flags = 0 + + ## + # Table 55. LAUNCH_SECRET Packet Header Buffer + ## + header = ( + flags.to_bytes(4, byteorder='little') + + iv + ) + + # AMD Secure Encrypted Virtualization API , section 6.6 + # + # hdrmac = HMAC(0x01 || FLAGS || IV || GUEST_LENGTH || + # TRANS_LENGTH || DATA || + # MEASURE; GCTX.TIK) + # + msg = ( + bytes([0x01]) + + flags.to_bytes(4, byteorder='little') + + iv + + len(secret_table).to_bytes(4, byteorder='little') + + len(secret_table).to_bytes(4, byteorder='little') + + secret_table_ciphertext + + measurement + ) + + h = hmac.new(self.tik, msg, 'sha256') + header = ( + flags.to_bytes(4, byteorder='little') + + iv + + h.digest() + ) + + header64 = b64encode(header).decode('utf8') + secret64 = b64encode(secret_table_ciphertext).decode('utf8') + log.debug("Header: %s (%d bytes)", header64, len(header)) + log.debug("Secret: %s (%d bytes)", + secret64, len(secret_table_ciphertext)) + + return header64, secret64 + + @abc.abstractmethod + def inject_secrets(self): + pass + + +class OfflineConfidentialVM(ConfidentialVM): + def __init__(self, + secret_header=None, + secret_payload=None, + **kwargs): + super().__init__(**kwargs) + + self.secret_header = secret_header + self.secret_payload = secret_payload + + def inject_secrets(self): + header64, secret64 = self.build_secrets() + + with open(self.secret_header, "wb") as fh: + fh.write(header64.encode('utf8')) + with open(self.secret_payload, "wb") as fh: + fh.write(secret64.encode('utf8')) + class LibvirtConfidentialVM(ConfidentialVM): def __init__(self, **kwargs): @@ -944,6 +1063,14 @@ class LibvirtConfidentialVM(ConfidentialVM): cpu_stepping = int(sig[0].get("stepping")) self.build_vmsas(cpu_family, cpu_model, cpu_stepping) + def inject_secrets(self): + header64, secret64 = self.build_secrets() + + params = {"sev-secret": secret64, + "sev-secret-header": header64} + self.dom.setLaunchSecurityState(params, 0) + self.dom.resume() + def parse_command_line(): parser = argparse.ArgumentParser( @@ -1006,6 +1133,15 @@ def parse_command_line(): vmconn.add_argument('--ignore-config', '-g', action='store_true', help='Do not attempt to sanity check the guest config') + # Arguments related to secret injection + inject = parser.add_argument_group("Secret injection parameters") + inject.add_argument('--inject-secret', '-s', action='append', default=[], + help='ALIAS-OR-GUID:PATH file containing secret to inject') + inject.add_argument('--secret-payload', + help='Path to file to write secret data payload to') + inject.add_argument('--secret-header', + help='Path to file to write secret data header to') + return parser.parse_args() @@ -1046,6 +1182,15 @@ def check_usage(args): raise UnsupportedUsageException( "Either --firmware or --domain is required") + if len(args.inject_secret) > 0: + if args.secret_header is None: + raise UnsupportedUsageException( + "Either --secret-header or --domain is required") + + if args.secret_payload is None: + raise UnsupportedUsageException( + "Either --secret-payload or --domain is required") + if args.kernel is None: if args.initrd is not None or args.cmdline is not None: raise UnsupportedUsageException( @@ -1065,15 +1210,22 @@ def check_usage(args): raise UnsupportedUsageException( "CPU SKU needs family, model and stepping for SEV-ES domain") + secret = [args.secret_payload, args.secret_header] + if secret.count(None) > 0 and secret.count(None) != len(secret): + raise UnsupportedUsageException( + "Both --secret-payload and --secret-header are required") + def attest(args): if args.domain is None: - cvm = ConfidentialVM(measurement=args.measurement, - api_major=args.api_major, - api_minor=args.api_minor, - build_id=args.build_id, - policy=args.policy, - num_cpus=args.num_cpus) + cvm = OfflineConfidentialVM(measurement=args.measurement, + api_major=args.api_major, + api_minor=args.api_minor, + build_id=args.build_id, + policy=args.policy, + num_cpus=args.num_cpus, + secret_header=args.secret_header, + secret_payload=args.secret_payload) else: cvm = LibvirtConfidentialVM(measurement=args.measurement, api_major=args.api_major, @@ -1117,10 +1269,23 @@ def attest(args): args.ignore_config) cvm.attest() - if not args.quiet: print("OK: Looks good to me") + for secret in args.inject_secret: + bits = secret.split(":") + if len(bits) != 2: + raise UnsupportedUsageException( + "Expecting ALIAS-OR-GUID:PATH for injected secret") + + cvm.secrets_table.load_secret(bits[0], bits[1]) + + if len(args.inject_secret) > 0: + cvm.inject_secrets() + if not args.quiet: + print("OK: Injected %d secrets" % len(args.inject_secret)) + + def main(): args = parse_command_line() if args.debug: -- 2.37.3

In general we expect to be able to construct a SEV-ES VMSA blob from knowledge about the AMD achitectural CPU register defaults, KVM setup and QEMU setup. If any of this unexpectedly changes, figuring out what's wrong could be horrible. This systemtap script demonstrates how to capture the real VMSA that is used for a SEV-ES as it is booted. The captured data can be fed into the 'sevctl vmsa show' command in order to produce formatted info with named registers, allowing a 'diff' to be performed. This script will need updating for any kernel version that is not 6.0, to set the correct line numbers. Reviewed-by: Ján Tomko <jtomko(a)redhat.com&gt; Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; --- examples/systemtap/amd-sev-es-vmsa.stp | 48 ++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 examples/systemtap/amd-sev-es-vmsa.stp diff --git a/examples/systemtap/amd-sev-es-vmsa.stp b/examples/systemtap/amd-sev-es-vmsa.stp new file mode 100644 index 0000000000..551ed739b7 --- /dev/null +++ b/examples/systemtap/amd-sev-es-vmsa.stp @@ -0,0 +1,48 @@ +#!/usr/bin/stap +# +# Copyright (C) 2022 Red Hat, Inc. +# +# This library is free software; you can redistribute it and/or +# modify it under the terms of the GNU Lesser General Public +# License as published by the Free Software Foundation; either +# version 2.1 of the License, or (at your option) any later version. +# +# This library is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +# Lesser General Public License for more details. +# +# You should have received a copy of the GNU Lesser General Public +# License along with this library. If not, see +# <http://www.gnu.org/licenses/>;. +# +# A script that captures the VMSA blob for the boot vCPU and +# first additional vCPU, when a KVM guest is booted with SEV-ES +# +# The captured VMSA will be printed to the console in hex format, +# and can be converted to the required binary format by feeding +# it through +# +# perl -e 'while (<>) { print pack("C64", map { hex($_) } ( $_ =~ m/../g )); }' > vmsa.bin +# + +probe begin { + printf("Running\n") +} + +function dump_vmsa(addr:long) { + printf("VMSA\n") + for (i = 0; i < 4096 ; i+= 64) { + printf("%.64M\n", addr + i); + } +} + +# This line number will need to be updated for the specific kernel +# version that is being probed. The line that needs to be targetted +# is the one beween the call to clflush_cache_range(...) and the +# call to sev_issue_cmd(kvm, SEV_CMD_LAUNCH_UPDATE...). +# +# Line 632 is correct for Linux v6.0 +probe module("kvm_amd").statement("__sev_launch_update_vmsa@arch/x86/kvm/svm/sev.c:632") { + dump_vmsa($svm->vmsa) +} -- 2.37.3