| Message ID | 20201003045059.665934-16-jarkko.sakkinen@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Intel SGX foundations | expand |
> int __init sgx_drv_init(void) > { > unsigned int eax, ebx, ecx, edx; > @@ -181,5 +192,12 @@ int __init sgx_drv_init(void) > return ret; > } > > + ret = misc_register(&sgx_dev_provision); > + if (ret) { > + pr_err("Creating /dev/sgx/provision failed with %d.\n", ret); > + misc_deregister(&sgx_dev_enclave); > + return ret; > + } > + Isn't it a *bit* too specific to say that a device file failed to be created? Do other misc devices use this kind of message?
On 10/2/20 9:50 PM, Jarkko Sakkinen wrote: > + * Failure to explicitly request access to a restricted attribute will cause > + * sgx_ioc_enclave_init() to fail. Currently, the only restricted attribute > + * is access to the PROVISION_KEY. Could we also justify why access is restricted, please? Maybe: Access is restricted because PROVISION_KEY is burned uniquely into each each processor, making it a perfect unique identifier with privacy and fingerprinting implications. Are there any other reasons for doing it this way?
On Tue, Oct 20, 2020 at 08:48:54AM -0700, Dave Hansen wrote: > > int __init sgx_drv_init(void) > > { > > unsigned int eax, ebx, ecx, edx; > > @@ -181,5 +192,12 @@ int __init sgx_drv_init(void) > > return ret; > > } > > > > + ret = misc_register(&sgx_dev_provision); > > + if (ret) { > > + pr_err("Creating /dev/sgx/provision failed with %d.\n", ret); > > + misc_deregister(&sgx_dev_enclave); > > + return ret; > > + } > > + > > Isn't it a *bit* too specific to say that a device file failed to be > created? Do other misc devices use this kind of message? Before seeing this I had already removed it. It is incosistent at least and quite useless error really. We have tracing tools for this. /Jarkko
On Tue, Oct 20, 2020 at 02:19:26PM -0700, Dave Hansen wrote: > On 10/2/20 9:50 PM, Jarkko Sakkinen wrote: > > + * Failure to explicitly request access to a restricted attribute will cause > > + * sgx_ioc_enclave_init() to fail. Currently, the only restricted attribute > > + * is access to the PROVISION_KEY. > > Could we also justify why access is restricted, please? Maybe: > > Access is restricted because PROVISION_KEY is burned uniquely > into each each processor, making it a perfect unique identifier > with privacy and fingerprinting implications. > > Are there any other reasons for doing it this way? AFAIK, if I interperet the SDM correctl, PROVISION_KEY and PROVISION_SEALING_KEY also have random salt added, i.e. they change every boot cycle. There is "RAND = yes" on those keys in Table 40-64 of Intel SDM volume 3D :-) /Jarkko
On 10/23/20 3:17 AM, Jarkko Sakkinen wrote: > On Tue, Oct 20, 2020 at 02:19:26PM -0700, Dave Hansen wrote: >> On 10/2/20 9:50 PM, Jarkko Sakkinen wrote: >>> + * Failure to explicitly request access to a restricted attribute will cause >>> + * sgx_ioc_enclave_init() to fail. Currently, the only restricted attribute >>> + * is access to the PROVISION_KEY. >> Could we also justify why access is restricted, please? Maybe: >> >> Access is restricted because PROVISION_KEY is burned uniquely >> into each each processor, making it a perfect unique identifier >> with privacy and fingerprinting implications. >> >> Are there any other reasons for doing it this way? > AFAIK, if I interperet the SDM correctl, PROVISION_KEY and > PROVISION_SEALING_KEY also have random salt added, i.e. they change > every boot cycle. > > There is "RAND = yes" on those keys in Table 40-64 of Intel SDM volume > 3D :-) Does that mean there are no privacy implications from access to the provisioning keys? If that's true, why do we need a separate permission framework for creating provisioning enclaves?
On 2020-10-23 12:17, Jarkko Sakkinen wrote: > On Tue, Oct 20, 2020 at 02:19:26PM -0700, Dave Hansen wrote: >> On 10/2/20 9:50 PM, Jarkko Sakkinen wrote: >>> + * Failure to explicitly request access to a restricted attribute will cause >>> + * sgx_ioc_enclave_init() to fail. Currently, the only restricted attribute >>> + * is access to the PROVISION_KEY. >> >> Could we also justify why access is restricted, please? Maybe: >> >> Access is restricted because PROVISION_KEY is burned uniquely >> into each each processor, making it a perfect unique identifier >> with privacy and fingerprinting implications. >> >> Are there any other reasons for doing it this way? > > AFAIK, if I interperet the SDM correctl, PROVISION_KEY and > PROVISION_SEALING_KEY also have random salt added, i.e. they change > every boot cycle. > > There is "RAND = yes" on those keys in Table 40-64 of Intel SDM volume > 3D :-) > This is nonsense. The whole point of sealing keys is that they don't change every boot. If did they they'd have no value over enclave memory. RAND means that the KEYID field from the KEYREQUEST is included in the derivation (as noted in the source row of the table you looked at). -- Jethro Beekman | Fortanix
On Fri, Oct 23, 2020 at 07:19:05AM -0700, Dave Hansen wrote: > On 10/23/20 3:17 AM, Jarkko Sakkinen wrote: > > On Tue, Oct 20, 2020 at 02:19:26PM -0700, Dave Hansen wrote: > >> On 10/2/20 9:50 PM, Jarkko Sakkinen wrote: > >>> + * Failure to explicitly request access to a restricted attribute will cause > >>> + * sgx_ioc_enclave_init() to fail. Currently, the only restricted attribute > >>> + * is access to the PROVISION_KEY. > >> Could we also justify why access is restricted, please? Maybe: > >> > >> Access is restricted because PROVISION_KEY is burned uniquely > >> into each each processor, making it a perfect unique identifier > >> with privacy and fingerprinting implications. > >> > >> Are there any other reasons for doing it this way? > > AFAIK, if I interperet the SDM correctl, PROVISION_KEY and > > PROVISION_SEALING_KEY also have random salt added, i.e. they change > > every boot cycle. > > > > There is "RAND = yes" on those keys in Table 40-64 of Intel SDM volume > > 3D :-) > > Does that mean there are no privacy implications from access to the > provisioning keys? If that's true, why do we need a separate permission > framework for creating provisioning enclaves? As I've understood it, the key material for those keys is not even required in the current SGX architecture, it was used in the legacy EPID scheme, but the attribute itself is useful. Let's assume that we have some sort of quoting enclave Q, which guards a public key pair, which signs quotes of other enclaves. Let's assume we have an attestation server A, which will enable some capabilities [*], if it receives a quote signed with that public key pair. 1. E gets the report key with EGETKEY. 2. E constructs REPORTDATA (37.16) and TARGETINFO (37.17) structures. The former describes the enclaves contents and attributes and latter the target, i.e. Q in this artitificial example. 3. E calls EREPORT to generate a structure called REPORT MAC'd with the *targets* report key. It knows, which key to usue from REPORTDATA. 4. The runtime will then pass this to Q. 5. Q will check if ATTRIBUTE.PROVISION_KEY is set. If it is, Q will know that the enclave is allowed to get attested. Then it will sign the report with the guarded public key pair and send it to the attestation server. The example is artificial, e.g. there could be something more complex, but the idea is essentially this. [*] With TPM and measured boot this could be to open network for a data center node. Quote is just the term used for a signed measurement in remote attestation schemes generally. /Jarkko
On Fri, Oct 23, 2020 at 04:23:55PM +0200, Jethro Beekman wrote: > On 2020-10-23 12:17, Jarkko Sakkinen wrote: > > On Tue, Oct 20, 2020 at 02:19:26PM -0700, Dave Hansen wrote: > >> On 10/2/20 9:50 PM, Jarkko Sakkinen wrote: > >>> + * Failure to explicitly request access to a restricted attribute will cause > >>> + * sgx_ioc_enclave_init() to fail. Currently, the only restricted attribute > >>> + * is access to the PROVISION_KEY. > >> > >> Could we also justify why access is restricted, please? Maybe: > >> > >> Access is restricted because PROVISION_KEY is burned uniquely > >> into each each processor, making it a perfect unique identifier > >> with privacy and fingerprinting implications. > >> > >> Are there any other reasons for doing it this way? > > > > AFAIK, if I interperet the SDM correctl, PROVISION_KEY and > > PROVISION_SEALING_KEY also have random salt added, i.e. they change > > every boot cycle. > > > > There is "RAND = yes" on those keys in Table 40-64 of Intel SDM volume > > 3D :-) > > > > This is nonsense. The whole point of sealing keys is that they don't > change every boot. If did they they'd have no value over enclave > memory. RAND means that the KEYID field from the KEYREQUEST is > included in the derivation (as noted in the source row of the table > you looked at). I just looked that the column name is RAND, the row is called "Provision key" and the cell has "Yes" in it. > -- > Jethro Beekman | Fortanix /Jarkko
On Sat, Oct 24, 2020 at 4:34 AM Jarkko Sakkinen <kernel.org@kernel.org> wrote: > > On Fri, Oct 23, 2020 at 07:19:05AM -0700, Dave Hansen wrote: > > On 10/23/20 3:17 AM, Jarkko Sakkinen wrote: > > > On Tue, Oct 20, 2020 at 02:19:26PM -0700, Dave Hansen wrote: > > >> On 10/2/20 9:50 PM, Jarkko Sakkinen wrote: > > >>> + * Failure to explicitly request access to a restricted attribute will cause > > >>> + * sgx_ioc_enclave_init() to fail. Currently, the only restricted attribute > > >>> + * is access to the PROVISION_KEY. > > >> Could we also justify why access is restricted, please? Maybe: > > >> > > >> Access is restricted because PROVISION_KEY is burned uniquely > > >> into each each processor, making it a perfect unique identifier > > >> with privacy and fingerprinting implications. > > >> > > >> Are there any other reasons for doing it this way? > > > AFAIK, if I interperet the SDM correctl, PROVISION_KEY and > > > PROVISION_SEALING_KEY also have random salt added, i.e. they change > > > every boot cycle. > > > > > > There is "RAND = yes" on those keys in Table 40-64 of Intel SDM volume > > > 3D :-) > > > > Does that mean there are no privacy implications from access to the > > provisioning keys? If that's true, why do we need a separate permission > > framework for creating provisioning enclaves? > > As I've understood it, the key material for those keys is not even > required in the current SGX architecture, it was used in the legacy EPID > scheme, but the attribute itself is useful. > > Let's assume that we have some sort of quoting enclave Q, which guards a > public key pair, which signs quotes of other enclaves. Let's assume we > have an attestation server A, which will enable some capabilities [*], > if it receives a quote signed with that public key pair. > > 1. E gets the report key with EGETKEY. > 2. E constructs REPORTDATA (37.16) and TARGETINFO (37.17) structures. > The former describes the enclaves contents and attributes and latter > the target, i.e. Q in this artitificial example. > 3. E calls EREPORT to generate a structure called REPORT MAC'd with the > *targets* report key. It knows, which key to usue from REPORTDATA. > 4. The runtime will then pass this to Q. > 5. Q will check if ATTRIBUTE.PROVISION_KEY is set. If it is, Q will > know that the enclave is allowed to get attested. Then it will > sign the report with the guarded public key pair and send it to > the attestation server. I think you have this a little bit off. AIUI E won't have ATTRIBUTE.PROVISION_KEY set -- Q will. Q uses the provisioning key to convince an Intel server that it's running on a genuine Intel CPU, and the Intel server will return a signed certificate that Q can chain off of to generate attestations for E. Dave, I would rephrase what you're saying a bit. The PROVISION_KEY attribute allows enclaves to access keys that are unique to a processor and unchangeable. Unlike other SGX keys, these keys are not affected by OWNER_EPOCH changes and therefore cannot be reset. --Andy
On Sat, Oct 24, 2020 at 08:47:28AM -0700, Andy Lutomirski wrote: > On Sat, Oct 24, 2020 at 4:34 AM Jarkko Sakkinen <kernel.org@kernel.org> wrote: > > > > On Fri, Oct 23, 2020 at 07:19:05AM -0700, Dave Hansen wrote: > > > On 10/23/20 3:17 AM, Jarkko Sakkinen wrote: > > > > On Tue, Oct 20, 2020 at 02:19:26PM -0700, Dave Hansen wrote: > > > >> On 10/2/20 9:50 PM, Jarkko Sakkinen wrote: > > > >>> + * Failure to explicitly request access to a restricted attribute will cause > > > >>> + * sgx_ioc_enclave_init() to fail. Currently, the only restricted attribute > > > >>> + * is access to the PROVISION_KEY. > > > >> Could we also justify why access is restricted, please? Maybe: > > > >> > > > >> Access is restricted because PROVISION_KEY is burned uniquely > > > >> into each each processor, making it a perfect unique identifier > > > >> with privacy and fingerprinting implications. > > > >> > > > >> Are there any other reasons for doing it this way? > > > > AFAIK, if I interperet the SDM correctl, PROVISION_KEY and > > > > PROVISION_SEALING_KEY also have random salt added, i.e. they change > > > > every boot cycle. > > > > > > > > There is "RAND = yes" on those keys in Table 40-64 of Intel SDM volume > > > > 3D :-) > > > > > > Does that mean there are no privacy implications from access to the > > > provisioning keys? If that's true, why do we need a separate permission > > > framework for creating provisioning enclaves? > > > > As I've understood it, the key material for those keys is not even > > required in the current SGX architecture, it was used in the legacy EPID > > scheme, but the attribute itself is useful. > > > > Let's assume that we have some sort of quoting enclave Q, which guards a > > public key pair, which signs quotes of other enclaves. Let's assume we > > have an attestation server A, which will enable some capabilities [*], > > if it receives a quote signed with that public key pair. > > > > 1. E gets the report key with EGETKEY. > > 2. E constructs REPORTDATA (37.16) and TARGETINFO (37.17) structures. > > The former describes the enclaves contents and attributes and latter > > the target, i.e. Q in this artitificial example. > > 3. E calls EREPORT to generate a structure called REPORT MAC'd with the > > *targets* report key. It knows, which key to usue from REPORTDATA. > > 4. The runtime will then pass this to Q. > > 5. Q will check if ATTRIBUTE.PROVISION_KEY is set. If it is, Q will > > know that the enclave is allowed to get attested. Then it will > > sign the report with the guarded public key pair and send it to > > the attestation server. > > I think you have this a little bit off. AIUI E won't have > ATTRIBUTE.PROVISION_KEY set -- Q will. Q uses the provisioning key to > convince an Intel server that it's running on a genuine Intel CPU, and > the Intel server will return a signed certificate that Q can chain off > of to generate attestations for E. Right, I was confused by that RAND column, until Jethro corrected me. Actually, quoting enclave (QE) authorizes itself with a provisioning certification enclave (PCE), which holds certificates and revocation lists for provisioning secrets unique to a CPU. And the sequence that I described happens between PCE and QE. It accepts requests from enclaves with ATTRIBUTES.PROVISION key bits set to 1 according to: https://software.intel.com/content/dam/develop/external/us/en/documents/intel-sgx-support-for-third-party-attestation-801017.pdf The source code for the reference is available here: https://github.com/intel/SGXDataCenterAttestationPrimitives And binaries are here: https://01.org/intel-softwareguard-extensions/downloads/intel-sgx-dcap-1.6-release They are provided for the inevitable reason that, it is the way bind to the hardware, i.e. proof that you are running on a genuine CPU. The network part is that PCE and QE can certify to an application, if an enclave running in a different computer is an enclave. > Dave, I would rephrase what you're saying a bit. The PROVISION_KEY > attribute allows enclaves to access keys that are unique to a > processor and unchangeable. Unlike other SGX keys, these keys are not > affected by OWNER_EPOCH changes and therefore cannot be reset. /Jarkko
On Sat, Oct 24, 2020 at 11:23:11PM +0300, Jarkko Sakkinen wrote: Good morning, I hope the day is starting well for everyone. > On Sat, Oct 24, 2020 at 08:47:28AM -0700, Andy Lutomirski wrote: > > On Sat, Oct 24, 2020 at 4:34 AM Jarkko Sakkinen <kernel.org@kernel.org> wrote: > > > > > > On Fri, Oct 23, 2020 at 07:19:05AM -0700, Dave Hansen wrote: > > > > On 10/23/20 3:17 AM, Jarkko Sakkinen wrote: > > > > > On Tue, Oct 20, 2020 at 02:19:26PM -0700, Dave Hansen wrote: > > > > >> On 10/2/20 9:50 PM, Jarkko Sakkinen wrote: > > > > >>> + * Failure to explicitly request access to a restricted attribute will cause > > > > >>> + * sgx_ioc_enclave_init() to fail. Currently, the only restricted attribute > > > > >>> + * is access to the PROVISION_KEY. > > > > >> Could we also justify why access is restricted, please? Maybe: > > > > >> > > > > >> Access is restricted because PROVISION_KEY is burned uniquely > > > > >> into each each processor, making it a perfect unique identifier > > > > >> with privacy and fingerprinting implications. > > > > >> > > > > >> Are there any other reasons for doing it this way? > > > > > AFAIK, if I interperet the SDM correctl, PROVISION_KEY and > > > > > PROVISION_SEALING_KEY also have random salt added, i.e. they change > > > > > every boot cycle. > > > > > > > > > > There is "RAND = yes" on those keys in Table 40-64 of Intel SDM volume > > > > > 3D :-) > > > > > > > > Does that mean there are no privacy implications from access to the > > > > provisioning keys? If that's true, why do we need a separate permission > > > > framework for creating provisioning enclaves? > > > > > > As I've understood it, the key material for those keys is not even > > > required in the current SGX architecture, it was used in the legacy EPID > > > scheme, but the attribute itself is useful. > > > > > > Let's assume that we have some sort of quoting enclave Q, which guards a > > > public key pair, which signs quotes of other enclaves. Let's assume we > > > have an attestation server A, which will enable some capabilities [*], > > > if it receives a quote signed with that public key pair. > > > > > > 1. E gets the report key with EGETKEY. > > > 2. E constructs REPORTDATA (37.16) and TARGETINFO (37.17) structures. > > > The former describes the enclaves contents and attributes and latter > > > the target, i.e. Q in this artitificial example. > > > 3. E calls EREPORT to generate a structure called REPORT MAC'd with the > > > *targets* report key. It knows, which key to usue from REPORTDATA. > > > 4. The runtime will then pass this to Q. > > > 5. Q will check if ATTRIBUTE.PROVISION_KEY is set. If it is, Q will > > > know that the enclave is allowed to get attested. Then it will > > > sign the report with the guarded public key pair and send it to > > > the attestation server. > > > > I think you have this a little bit off. AIUI E won't have > > ATTRIBUTE.PROVISION_KEY set -- Q will. Q uses the provisioning key to > > convince an Intel server that it's running on a genuine Intel CPU, and > > the Intel server will return a signed certificate that Q can chain off > > of to generate attestations for E. > Right, I was confused by that RAND column, until Jethro corrected me. The RAND column is probably misnamed, it doesn't really imply random in the common sense of the meaning. It implies that a 256 bit nonce (keyid) can be supplied to the ENCLU[EGETKEY] instruction to perturb the key derivation process. The value is actually available in plaintext form as part of the metadata for sealed data. If it was really a random value, attestation wouldn't work. > Actually, quoting enclave (QE) authorizes itself with a provisioning > certification enclave (PCE), which holds certificates and revocation > lists for provisioning secrets unique to a CPU. And the sequence that I > described happens between PCE and QE. It accepts requests from enclaves > with ATTRIBUTES.PROVISION key bits set to 1 according to: > > https://software.intel.com/content/dam/develop/external/us/en/documents/intel-sgx-support-for-third-party-attestation-801017.pdf > > The source code for the reference is available here: > > https://github.com/intel/SGXDataCenterAttestationPrimitives > > And binaries are here: > > https://01.org/intel-softwareguard-extensions/downloads/intel-sgx-dcap-1.6-release > > They are provided for the inevitable reason that, it is the way bind > to the hardware, i.e. proof that you are running on a genuine CPU. > > The network part is that PCE and QE can certify to an application, > if an enclave running in a different computer is an enclave. All of this discussion has lacked a certain amount of precision, as a result the original issue with respect to Dave's concern regarding the privacy implications of an enclave posessing the PROVISION_KEY attribute has been lost. First of all, it is important to note that two types of attestation are available, EPID and DCAP/ECDSA. They differ in their implementation with respect to which enclaves need to have access to derivation of the PROVISION_KEY. What does remain constant is the role that the PROVISION_KEY plays in all this. The Platform Certification Enclave (PCE) has two roles: 1.) Generate a Platform Provisioning IDentifier (PPID). 2.) Certification of the fact that an enclave, other then the PCE, is running on the same platform at a particular Trusted Computing Base (TCB) level. Being able to generate a PPID is the most privacy sensitive operation that an enclave can peform, hence the recommendation to restrict access to the attribute bit that allows an enclave to create a derivation of the root provisioning key. The PPID is a 256 bit symmetric key that is generated with the keyid and security version values all set to null values. As a result, any enclave with a given MRSIGNER value will generate the same key value. That value is used by Intel, and potentially others, to uniquely identify the platform as long as it exists. The PPID can be admixed with other information, such as the platform security version of an enclave, to create a unique identifier for the TCB state of enclave based software running on a particular platform. This is role 2 of the PCE that I noted above. In DCAP attestation, which is what Jarkko is referring to, both the Quoting Enclave (QE) and PCE have access to PROVISION_KEY derivation. In EPID attestation the PCE and the Provisioning Enclave (PVE) have access to PROVISION_KEY derivation. I guess it is up to community consensus as to whether or not this is a privacy/security sensitive issue. It provides precise enough identification that Intel uses it to determine whether or not a platform should be allowed or denied the ability to participate in EPID attestation. I believe that this is being used to to force the cloud based platforms to use DCAP rather then EPID based attestation. The provision keys for these SKU's are not included in the Intel Attestation Service (IAS) database so they cannot identify themselves for provisioning of an EPID private key. Since Intel has access to the root provisioning keys it can identify a platform a-priori. Other entities can use this infrastructure for uniquely identifying platforms but it has to be done via an enrollment process for a given signing key. > /Jarkko Hopefully the above clarifications are helpful. Have a good day. Dr. Greg As always, Dr. Greg Wettstein, Ph.D, Worker Autonomously self-defensive Enjellic Systems Development, LLC IOT platforms and edge devices. 4206 N. 19th Ave. Fargo, ND 58102 PH: 701-281-1686 EMAIL: greg@enjellic.com ------------------------------------------------------------------------------ "I suppose that could could happen but he wouldn't know a Galois Field if it kicked him in the nuts." -- Anonymous mathematician Resurrection.
diff --git a/arch/x86/include/uapi/asm/sgx.h b/arch/x86/include/uapi/asm/sgx.h index e401fa72eaab..b6ba036a9b82 100644 --- a/arch/x86/include/uapi/asm/sgx.h +++ b/arch/x86/include/uapi/asm/sgx.h @@ -25,6 +25,8 @@ enum sgx_page_flags { _IOWR(SGX_MAGIC, 0x01, struct sgx_enclave_add_pages) #define SGX_IOC_ENCLAVE_INIT \ _IOW(SGX_MAGIC, 0x02, struct sgx_enclave_init) +#define SGX_IOC_ENCLAVE_PROVISION \ + _IOW(SGX_MAGIC, 0x03, struct sgx_enclave_provision) /** * struct sgx_enclave_create - parameter structure for the @@ -63,4 +65,13 @@ struct sgx_enclave_init { __u64 sigstruct; }; +/** + * struct sgx_enclave_provision - parameter structure for the + * %SGX_IOC_ENCLAVE_PROVISION ioctl + * @attribute_fd: file handle of the attribute file in the securityfs + */ +struct sgx_enclave_provision { + __u64 attribute_fd; +}; + #endif /* _UAPI_ASM_X86_SGX_H */ diff --git a/arch/x86/kernel/cpu/sgx/driver.c b/arch/x86/kernel/cpu/sgx/driver.c index 7bdb49dfcca6..d01b28f7ce4a 100644 --- a/arch/x86/kernel/cpu/sgx/driver.c +++ b/arch/x86/kernel/cpu/sgx/driver.c @@ -134,6 +134,10 @@ static const struct file_operations sgx_encl_fops = { .get_unmapped_area = sgx_get_unmapped_area, }; +const struct file_operations sgx_provision_fops = { + .owner = THIS_MODULE, +}; + static struct miscdevice sgx_dev_enclave = { .minor = MISC_DYNAMIC_MINOR, .name = "enclave", @@ -141,6 +145,13 @@ static struct miscdevice sgx_dev_enclave = { .fops = &sgx_encl_fops, }; +static struct miscdevice sgx_dev_provision = { + .minor = MISC_DYNAMIC_MINOR, + .name = "provision", + .nodename = "sgx/provision", + .fops = &sgx_provision_fops, +}; + int __init sgx_drv_init(void) { unsigned int eax, ebx, ecx, edx; @@ -181,5 +192,12 @@ int __init sgx_drv_init(void) return ret; } + ret = misc_register(&sgx_dev_provision); + if (ret) { + pr_err("Creating /dev/sgx/provision failed with %d.\n", ret); + misc_deregister(&sgx_dev_enclave); + return ret; + } + return 0; } diff --git a/arch/x86/kernel/cpu/sgx/driver.h b/arch/x86/kernel/cpu/sgx/driver.h index e4063923115b..72747d01c046 100644 --- a/arch/x86/kernel/cpu/sgx/driver.h +++ b/arch/x86/kernel/cpu/sgx/driver.h @@ -23,6 +23,8 @@ extern u64 sgx_attributes_reserved_mask; extern u64 sgx_xfrm_reserved_mask; extern u32 sgx_xsave_size_tbl[64]; +extern const struct file_operations sgx_provision_fops; + long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg); int sgx_drv_init(void); diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c index cf5a43d6daa2..3c04798e83e5 100644 --- a/arch/x86/kernel/cpu/sgx/ioctl.c +++ b/arch/x86/kernel/cpu/sgx/ioctl.c @@ -679,6 +679,49 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg) return ret; } +/** + * sgx_ioc_enclave_provision - handler for %SGX_IOC_ENCLAVE_PROVISION + * @enclave: an enclave pointer + * @arg: userspace pointer to a struct sgx_enclave_provision instance + * + * Mark the enclave as being allowed to access a restricted attribute bit. + * The requested attribute is specified via the attribute_fd field in the + * provided struct sgx_enclave_provision. The attribute_fd must be a + * handle to an SGX attribute file, e.g. "/dev/sgx/provision". + * + * Failure to explicitly request access to a restricted attribute will cause + * sgx_ioc_enclave_init() to fail. Currently, the only restricted attribute + * is access to the PROVISION_KEY. + * + * Note, access to the EINITTOKEN_KEY is disallowed entirely. + * + * Return: 0 on success, -errno otherwise + */ +static long sgx_ioc_enclave_provision(struct sgx_encl *encl, void __user *arg) +{ + struct sgx_enclave_provision params; + struct file *attribute_file; + int ret; + + if (copy_from_user(¶ms, arg, sizeof(params))) + return -EFAULT; + + attribute_file = fget(params.attribute_fd); + if (!attribute_file) + return -EINVAL; + + if (attribute_file->f_op != &sgx_provision_fops) { + ret = -EINVAL; + goto out; + } + + encl->attributes_mask |= SGX_ATTR_PROVISIONKEY; + ret = 0; + +out: + fput(attribute_file); + return ret; +} long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) { @@ -704,6 +747,9 @@ long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) case SGX_IOC_ENCLAVE_INIT: ret = sgx_ioc_enclave_init(encl, (void __user *)arg); break; + case SGX_IOC_ENCLAVE_PROVISION: + ret = sgx_ioc_enclave_provision(encl, (void __user *)arg); + break; default: ret = -ENOIOCTLCMD; break;