Graphene Manifest Syntax

Basic Syntax

A manifest file is an application-specific configuration text file that specifies the environment and resources for running an application inside Graphene. A manifest file contains entries separated by line breaks. Each configuration entry consists of a key and a value. Whitespaces before/after the key and before/after the value are ignored. The value can be written in quotes, indicating that the value should be assigned to this string verbatim. (The quotes syntax is useful for values with leading/trailing whitespaces, e.g. " SPACES! ".) Each entry must be in the following format:

[Key][.Key][.Key] = [Value]  or  [Key][.Key][.Key] = "[Value]"

Comments can be inlined in a manifest by starting them with a hash sign (# comment...). Any text after a hash sign will be considered part of a comment and discarded while loading the manifest file.

SGX syntax

If Graphene is not running with SGX, the SGX-specific syntax is ignored. All keys in the SGX-specific syntax are optional.

Enclave Size

sgx.enclave_size=[SIZE]
(default: 256M)

This syntax specifies the size of the enclave set during enclave creation time (recall that SGX v1 requires a predetermined maximum size of the enclave). The PAL and library OS code/data count towards this size value, as well as the application memory itself: application’s code, stack, heap, loaded application libraries, etc. The application cannot allocate memory that exceeds this limit.

Number of Threads

sgx.thread_num=[NUM]
(Default: 4)

This syntax specifies the maximum number of threads that can be created inside the enclave (recall that SGX v1 requires a predetermined maximum number of thread slots). The application cannot have more threads than this limit at a time (however, it is possible to create new threads after old threads are destroyed).

Number of RPC Threads (Exitless Feature)

sgx.rpc_thread_num=[NUM]
(Default: 0)

This syntax specifies the number of RPC threads that are created outside of the enclave. RPC threads are helper threads that run in untrusted mode alongside enclave threads. RPC threads issue system calls on behalf of enclave threads. This allows “exitless” design when application threads never leave the enclave (except for a few syscalls where there is no benefit, e.g., nanosleep()).

If user specifies 0 or omits this directive, then no RPC threads are created and all system calls perform an enclave exit (“normal” execution).

Note that the number of created RPC threads must match the maximum number of simultaneous enclave threads. If there are more RPC threads, then CPU time is wasted. If there are less RPC threads, some enclave threads may starve, especially if there are many blocking system calls by other enclave threads.

The Exitless feature may be detrimental for performance. It trades slow OCALLs/ECALLs for fast shared-memory communication at the cost of occupying more CPU cores and burning more CPU cycles. For example, a single-threaded Redis instance on Linux becomes 5-threaded on Graphene with Exitless. Thus, Exitless may negatively impact throughput but may improve latency.

Debug/Production Enclave

sgx.debug=[1|0]
(Default: 1)

This syntax specifies whether the enclave can be debugged. Set it to 1 for a debug enclave and to 0 for a production enclave.

Optional CPU features (AVX, AVX512, MPX)

sgx.require_avx=[1|0]
sgx.require_avx512=[1|0]
sgx.require_mpx=[1|0]
(Default: 0)

This syntax ensures that the CPU features are available and enabled for the enclave. If the options are set in the manifest but the features are unavailable on the platform, enclave initialization should fail. If the options are unset, enclave initialization should succeed even if these features are unavailable on the platform.

ISV Product ID and SVN

sgx.isvprodid=[NUM]
sgx.isnsvn=[NUM]
(Default: 0)

This syntax specifies the ISV Product ID and SVN to be added to the enclave signature.

Allowed Files

sgx.allowed_files.[identifier]=[URI]

This syntax specifies the files that are allowed to be loaded into the enclave unconditionally. These files are not cryptographically hashed and are thus not protected. It is insecure to allow files containing code or critical information; developers must not allow files blindly! Instead, use trusted or protected files.

Trusted Files

sgx.trusted_files.[identifier]=[URI]

This syntax specifies the files to be cryptographically hashed, and thus allowed to be loaded into the enclave. The signer tool will automatically generate hashes of these files and add them into the SGX-specific manifest (.manifest.sgx). This is especially useful for shared libraries: a trusted library cannot be silently replaced by a malicious host because the hash verification will fail.

Protected Files

sgx.protected_files_key=[16-byte hex value]
sgx.protected_files.[identifier]=[URI]

This syntax specifies the files that are encrypted on disk and transparently decrypted when accessed by Graphene or by application running inside Graphene. Protected files guarantee data confidentiality and integrity (tamper resistance), as well as file swap protection (a protected file can only be accessed when in a specific path).

URIs can be files or directories. If a directory is specified, all existing files/directories within it are registered as protected recursively (and are expected to be encrypted in the PF format). New files created in a protected directory are automatically treated as protected.

Note that path size of a protected file is limited to 512 bytes and filename size is limited to 260 bytes.

sgx.protected_files_key specifies the wrap (master) encryption key and must be used only for debugging purposes. In production environments, this key must be provisioned to the enclave using local/remote attestation.

Allowing File Creation

sgx.allow_file_creation=[1|0]
(Default: 0)

This syntax specifies whether file creation is allowed from within the enclave. Set it to 1 to allow enclaves to create files and to 0 otherwise. Files created during enclave execution do not need to be marked as allowed_files or trusted_files.

Trusted Child Processes

sgx.trusted_children.[identifier]=[URI of signature (.sig)]

This syntax specifies the signatures of allowed child processes of the current application. Upon process creation, the enclave in the current (parent) process will attest the enclave in the child process, by comparing to the signatures of the trusted children. If the child process is not trusted, the enclave will refuse to communicate with it.

File Check Policy

sgx.file_check_policy=[strict|allow_all_but_log]
(Default: strict)

This syntax specifies the file check policy, determining the behavior of authentication when opening files. By default, only files explicitly listed as _trusted_files_ or _allowed_files_ declared in the manifest are allowed for access. If the file check policy is allow_all_but_log, all files other than trusted and allowed are allowed for access, and Graphene-SGX emits a warning message for every such file. This is a convenient way to determine the set of files that the ported application uses.

Attestation and Quotes

sgx.remote_attestation=[1|0]
(Default: 0)
sgx.ra_client_linkable=[1|0]
(Default: 0)
sgx.ra_client_spid=[HEX]

This syntax specifies the parameters for remote attestation. To enable it, remote_attestation must be set to 1.

For ECDSA/DCAP based attestation, no additional parameters are required. For EPID based attestation, ra_client_linkable and ra_client_spid must be additionally specified (linkable/unlinkable mode and SPID of the client respectively).

Enabling per-thread and process-wide SGX stats

sgx.enable_stats=[1|0]
(Default: 0)

This syntax specifies whether to enable SGX enclave-specific statistics:

  1. TCS.FLAGS.DBGOPTIN flag. This flag is set in all enclave threads and enables certain debug and profiling features with enclaves, including breakpoints, performance counters, Intel PT, etc.

  2. Printing the stats on SGX-specific events. Currently supported stats are: number of EENTERs (corresponds to ECALLs plus returns from OCALLs), number of EEXITs (corresponds to OCALLs plus returns from ECALLs) and number of AEXs (corresponds to interrupts/exceptions/signals during enclave execution). Prints per-thread and per-process stats.

Note: this option is insecure and cannot be used with production enclaves (sgx.debug = 0). If the production enclave is started with this option set, Graphene will fail initialization of the enclave.