Manifest 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 key-value pairs (as well as more complicated table and array objects) in the TOML syntax. For the details of the TOML syntax, see the official documentation.

A typical string entry looks like this:

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

A typical integer entry looks similar to the above but without double quotes:

[Key][.Key][.Key] = [Value]

Comments can be inlined in a manifest by starting them with a hash sign (# comment...).

There is also a preprocessor available: graphene-manifest, which renders manifests from Jinja templates.

Common syntax

Log level

loader.log_level = "[none|error|warning|debug|trace|all]"
(Default: "error")

loader.log_file = "[PATH]"

This configures Graphene’s debug log. The log_level option specifies what messages to enable (e.g. loader.log_level = "debug" will enable all messages of type error, warning and debug). By default, the messages are printed to the standard error. If log_file is specified, the messages will be appended to that file.

Graphene outputs log messages of the following types:

  • error: A serious error preventing Graphene from operating properly (for example, error initializing one of the components).
  • warning: A non-fatal issue. Might mean that application is requesting something unsupported or poorly emulated.
  • debug: Detailed information about Graphene’s operation and internals.
  • trace: More detailed information, such as all system calls requested by the application. Might contain a lot of noise.

Warning

Only error log level is suitable for production. Other levels may leak sensitive data.

Preloaded libraries

loader.preload = "[URI][,URI]..."

This syntax specifies the libraries to be preloaded before loading the executable. The URIs of the libraries must be separated by commas. The libraries must be ELF binaries. This usually contains the LibOS library libsysdb.so.

Entrypoint

libos.entrypoint = "[PATH]"

This specifies the first executable which is to be started when spawning a Graphene instance from this manifest file. Needs to be a path inside Graphene pointing to a mounted file. Relative paths will be interpreted as starting from the current working directory (i.e. from / by default, or fs.start_dir if specified).

The recommended usage is to provide an absolute path, and mount the executable at that path. For example:

libos.entrypoint = "/usr/bin/python3.8"

fs.mount.python.type = "chroot"
fs.mount.python.path = "/usr/bin/python3.8"
fs.mount.python.uri = "file:/usr/bin/python3.8"
# Or, if using a binary from your local directory:
# fs.mount.python.uri = "file:python3.8"

Note

Earlier, libos.entrypoint was a PAL URI. If you used it with a relative path, it’s probably enough to remove file: prefix (convert "file:hello" to "hello").

Command-line arguments

loader.argv0_override = "[STRING]"

This syntax specifies an arbitrary string (typically the executable name) that will be passed as the first argument (argv[0]) to the executable.

If the string is not specified in the manifest, the application will get argv[0] from graphene-direct or graphene-sgx invocation.

loader.insecure__use_cmdline_argv = true

or

loader.argv_src_file = "file:file_with_serialized_argv"

If you want your application to use commandline arguments you need to either set loader.insecure__use_cmdline_argv (insecure in almost all cases) or point loader.argv_src_file to a file containing output of Tools/argv_serializer.

loader.argv_src_file is intended to point to either a trusted file or a protected file. The former allows to securely hardcode arguments (current manifest syntax doesn’t allow to include them inline), the latter allows the arguments to be provided at runtime from an external (trusted) source.

Note

Pointing to a protected file is currently not supported, due to the fact that PF wrap key provisioning currently happens after setting up arguments.

Environment variables

loader.insecure__use_host_env = [true|false]

By default, environment variables from the host will not be passed to the app. This can be overridden by the option above, but most applications and runtime libraries trust their environment variables and are completely insecure when these are attacker-controlled. For example, an attacker can execute an additional dynamic library by specifying LD_PRELOAD variable.

To securely set up the execution environment for an app you should use one or both of the following options:

loader.env.[ENVIRON] = "[VALUE]"
loader.env_src_file = "file:file_with_serialized_envs"

loader.env.[ENVIRON] adds/overwrites a single environment variable and can be used multiple times to specify more than one variable.

loader.env_src_file allows to specify a URI to a file containing serialized environment, which can be generated using Tools/argv_serializer. This option is intended to point to either a trusted file or a protected file. The former allows to securely hardcode environments (in a more flexible way than loader.env.[ENVIRON] option), the latter allows the environments to be provided at runtime from an external (trusted) source.

Note

Pointing to a protected file is currently not supported, due to the fact that PF wrap key provisioning currently happens after setting up environment variables.

If the same variable is set in both, then loader.env.[ENVIRON] takes precedence.

Disabling ASLR

loader.insecure__disable_aslr = [true|false]
(Default: false)

This specifies whether to disable Address Space Layout Randomization (ASLR). Since disabling ASLR worsens security of the application, ASLR is enabled by default.

Check invalid pointers

libos.check_invalid_pointers = [true|false]
(Default: true)

This specifies whether to enable checks of invalid pointers on syscall invocations. In particular, when this manifest option is set to true, Graphene’s LibOS will return an EFAULT error code if a user-supplied buffer points to an invalid memory region. Setting this manifest option to false may improve performance for certain workloads but may also generate SIGSEGV/SIGBUS exceptions for some applications that specifically use invalid pointers (though this is not expected for most real-world applications).

Graphene internal metadata size

loader.pal_internal_mem_size = "[SIZE]"
(default: "0")

This syntax specifies how much additional memory Graphene reserves for its internal use (e.g., metadata for trusted/protected files, internal handles, etc.). By default, Graphene pre-allocates 64MB of internal memory for this metadata, but for huge workloads this limit may be not enough. In this case, Graphene loudly fails with “out of PAL memory” error. To run huge workloads, increase this limit by setting this option to e.g. 64M (this would result in a total of 128MB used by Graphene for internal metadata). Note that this limit is included in sgx.enclave_size, so if your enclave size is e.g. 512MB and you specify loader.pal_internal_mem_size = "64M", then your application is left with 384MB of usable memory.

Stack size

sys.stack.size = "[SIZE]"
(default: "256K")

This specifies the stack size of each thread in each Graphene process. The default value is determined by the library OS. Units like K (KiB), M (MiB), and G (GiB) can be appended to the values for convenience. For example, sys.stack.size = "1M" indicates a 1 MiB stack size.

Program break (brk) size

sys.brk.max_size = "[SIZE]"
(default: "256K")

This specifies the maximal program break (brk) size in each Graphene process. The default value of the program break size is determined by the library OS. Units like K (KiB), M (MiB), and G (GiB) can be appended to the values for convenience. For example, sys.brk.max_size = "1M" indicates a 1 MiB brk size.

Allowing eventfd

sys.insecure__allow_eventfd = [true|false]
(Default: false)

This specifies whether to allow system calls eventfd() and eventfd2(). Since eventfd emulation currently relies on the host, these system calls are disallowed by default due to security concerns.

External SIGTERM injection

sys.enable_sigterm_injection = [true|false]
(Default: false)

This specifies whether to allow for a one-time injection of SIGTERM signal into Graphene. Could be useful to handle graceful shutdown. Be careful! In SGX environment, the untrusted host could inject that signal in an arbitrary moment. Examine what your application’s SIGTERM handler does and whether it poses any security threat.

Root FS mount point

fs.root.[identifier].type = "[chroot|...]"
fs.root.[identifier].path = "[PATH]"
fs.root.[identifier].uri  = "[URI]"

This syntax specifies the root file system to be mounted inside the library OS. If not specified, then Graphene mounts the current working directory as the root. There can be only one root FS mount point specified in the manifest.

FS mount points

fs.mount.[identifier].type = "[chroot|tmpfs]"
fs.mount.[identifier].path = "[PATH]"
fs.mount.[identifier].uri  = "[URI]"

This syntax specifies how file systems are mounted inside the library OS. For dynamically linked binaries, usually at least one chroot mount point is required in the manifest (the mount point of the Glibc library).

Graphene currently supports two types of mount points:

  • chroot: Host-backed files. All host files and sub-directories found under [URI] are forwarded to the Graphene instance and placed under [PATH]. For example, with a host-level path specified as fs.mount.lib.uri = "file:graphene/Runtime/" and forwarded to Graphene via fs.mount.lib.path = "/lib", a host-level file graphene/Runtime/libc.so.6 is visible to graphenized application as /lib/libc.so.6. This concept is similar to FreeBSD’s chroot and to Docker’s named volumes. Files under chroot mount points support mmap and fork/clone.
  • tmpfs: Temporary in-memory-only files. These files are not backed by host-level files. The tmpfs files are created under [PATH] (this path is empty on Graphene instance startup) and are destroyed when a Graphene instance terminates. The [URI] parameter is always ignored. tmpfs is especially useful in trusted environments (like Intel SGX) for securely storing temporary files. This concept is similar to Linux’s tmpfs. Files under tmpfs mount points currently do not support mmap and each process has its own, non-shared tmpfs (i.e. processes don’t see each other’s files).

Start (current working) directory

fs.start_dir = "[URI]"

This syntax specifies the start (current working) directory. If not specified, then Graphene sets the root directory as the start directory (see fs.root).

SGX syntax

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

Debug/production enclave

sgx.debug = [true|false]
(Default: true)

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

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.

Non-PIE binaries

sgx.nonpie_binary = [true|false]
(Default: false)

This setting tells Graphene whether to use a specially crafted memory layout, which is required to support non-relocatable binaries (non-PIE).

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.

Optional CPU features (AVX, AVX512, MPX, PKRU)

sgx.require_avx    = [true|false]
sgx.require_avx512 = [true|false]
sgx.require_mpx    = [true|false]
sgx.require_pkru   = [true|false]
(Default: false)

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 will fail. If the options are unset, enclave initialization will succeed even if these features are unavailable on the platform.

ISV Product ID and SVN

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

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

Allowed files

sgx.allowed_files = [
  "[URI]",
  "[URI]",
]

This syntax specifies the files that are allowed to be created or loaded into the enclave unconditionally. In other words, allowed files can be opened for reading/writing and can be created if they do not exist already. Allowed files are not cryptographically hashed and are thus not protected.

Warning

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

# entries can be strings
sgx.trusted_files = [
  "[URI]",
  "[URI]",
]

# entries can also be tables
[[sgx.trusted_files]]
uri = "[URI]"
sha256 = "[HASH]"

This syntax specifies the files to be cryptographically hashed at build time, and allowed to be accessed by the app in runtime only if their hashes match. This implies that trusted files can be only opened for reading (not for writing) and cannot be created if they do not exist already. The signer tool will automatically generate hashes of these files and add them to the SGX-specific manifest (.manifest.sgx). The manifest writer may also specify the hash for a file using the TOML-table syntax, in the field sha256; in this case, hashing of the file will be skipped by the signer tool and the value in sha256 field will be used instead.

Marking files as trusted 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 = [
  "[URI]",
  "[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).

URI can be a file or a directory. 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.

Warning

sgx.protected_files_key hard-codes the key in the manifest. This option is thus insecure and must not be used in production environments! Typically, you want to provision the protected files wrap key using SGX local/remote attestation, thus you should not specify the sgx.protected_files_key manifest option at all. Instead, use the Secret Provisioning interface (see Attestation and Secret Provisioning).

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. Effectively, this policy operates on all unknown files as if they were listed as allowed_files. (However, this policy still does not allow writing/creating files specified as trusted.) This policy is a convenient way to determine the set of files that the ported application uses.

Attestation and quotes

sgx.remote_attestation = [true|false]
(Default: false)

sgx.ra_client_linkable = [true|false]
sgx.ra_client_spid     = "[HEX]"

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

For EPID based attestation, ra_client_linkable and ra_client_spid must be filled with your registered Intel SGX EPID Attestation Service credentials (linkable/unlinkable mode and SPID of the client respectively).

For DCAP/ECDSA based attestation, ra_client_spid must be an empty string (this is a hint to Graphene to use DCAP instead of EPID) and ra_client_linkable is ignored.

Pre-heating enclave

sgx.preheat_enclave = [true|false]
(Default: false)

When enabled, this option instructs Graphene to pre-fault all heap pages during initialization. This has a negative impact on the total run time, but shifts the EPC page faults cost to the initialization phase, which can be useful in a scenario where a server starts and receives connections / work packages only after some time. It also makes the later run time and latency much more predictable.

Please note that using this option makes sense only when the EPC is large enough to hold the whole heap area.

Enabling per-thread and process-wide SGX stats

sgx.enable_stats = [true|false]
(Default: false)

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.
  3. Printing the SGX enclave loading time at startup. The enclave loading time includes creating the enclave, adding enclave pages, measuring them and initializing the enclave.

Warning

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

SGX profiling

sgx.profile.enable = ["none"|"main"|"all"]
(Default: "none")

This syntax specifies whether to enable SGX profiling. Graphene must be compiled with DEBUG=1 or DEBUGOPT=1 for this option to work (the latter is advised).

If this option is set to main, the main process will collect IP samples and save them as sgx-perf.data. If it is set to all, all processes will collect samples and save them to sgx-perf-<PID>.data.

The saved files can be viewed with the perf tool, e.g. perf report -i sgx-perf.data.

See SGX profiling for more information.

Warning

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

sgx.profile.mode = ["aex"|"ocall_inner"|"ocall_outer"]
(Default: "aex")

Specifies what events to record:

  • aex: Records enclave state during asynchronous enclave exit (AEX). Use this to check where the CPU time is spent in the enclave.
  • ocall_inner: Records enclave state during OCALL.
  • ocall_outer: Records the outer OCALL function, i.e. what OCALL handlers are going to be executed. Does not include stack information (cannot be used with sgx.profile.with_stack = true).

See also OCALL profiling for more detailed advice regarding the OCALL modes.

sgx.profile.with_stack = [true|false]
(Default: false)

This syntax specifies whether to include stack information with the profiling data. This will enable perf report to show call chains. However, it will make the output file much bigger, and slow down the process.

sgx.profile.frequency = [INTEGER]
(Default: 50)

This syntax specifies approximate frequency at which profiling samples are taken (in samples per second). Lower values will mean less accurate results, but also lower overhead.

Note that the accuracy is limited by how often the process is interrupted by Linux scheduler: the effective maximum is 250 samples per second.

Note

This option applies only to aex mode. In the ocall_* modes, currently all samples are taken.

Deprecated options

Allowed/Trusted/Protected Files (deprecated schema)

sgx.allowed_files.[identifier] = "[URI]"
sgx.trusted_files.[identifier] = "[URI]"
sgx.protected_files.[identifier] = "[URI]"

These manifest options used the TOML-table schema that had a bogus [identifier] key. This excessive TOML-table schema was replaced with a more appropriate TOML-array one.