Change log (most important only):
- unify CPU context structures - now we have only one version -
`PAL_CONTEXT` - which is shared between LibOS and PALs and it should
depend only on the host architecture (not OS),
- syscalls emulation changed:
- dedicated LibOS stack is now used for syscalls emulation,
- removed one indirection level in syscalls table - now it stores
`shim_do_*` functions directly,
- signal handling - completely rewritten:
- all signal queues use proper locking schemes now,
- signals are handled *only* when returning to the user app from LibOS
or PAL,
- nested signals are now possible,
- the app is allowed to jump out of signal handler with the same
sematics as on normal Linux,
- signal altstack is now fully supported,
- syscall restarting is now supported,
- doing a backtrace from the signal handler works properly,
- disallow injecting host-level signals, with one exception, see
`sys.enable_sigterm_injection` manifest option for more details.
Commit "Introduce one, central manifest, zero-config children and
constant MRENCLAVE" broke GSC. This commit fixes GSC (mainly adjusts
it the single-manifest change in that commit). Also, significant
internal refactoring is done (no user-visible changes). Also, scripts
now explicitly use UTF-8 when reading/writing the manifest files because
they are written in TOML which forces UTF-8.
Seems that no one has used this feature since its deprecation 1.5 year
ago. Let's not clutter the main readme with it.
Also dropped a section from building instructions, as it was quite
useless.
Intel SGX driver was upstreamed in Linux version 5.11. There, the SGX
device is exposed as `/dev/sgx_enclave` instead of `/dev/sgx/enclave`.
This commit updates link-intel-driver.py to recognize this new name.
This commit also fixes `pseudo_name_ops::list_name()` function pointer
type: `size_t len` argument instead of `int len`. It also adds a
regression test to exercise the newly supported /sys pseudo filesystem.
Previously, LibOS always checked whether user-supplied buffers for
syscalls are invalid and generated EFAULT error codes if so. Since the
invalid-buffer check needed to touch memory/traverse VMAs, it could
affect performance of certain workloads. This commit adds a manifest
option that controls this behavior: most real-world applications never
supply invalid buffers in syscalls, so such checks can be disabled.
Instead of 'loader.debug_type', introduce 'loader.log_level'
and 'loader.log_file', along with a set of definitions for
logging at a chosen level.
For now, the call sites keep using the legacy macros (SGX_DBG and
debug()), because converting them all will conflict with other
big changes in the code base. The existing LibOS calls are
assumed to be at 'info' level.
- Use the same mechanism (debug_map) in Pal/Linux and Pal/Linux-SGX.
Previously, Pal/Linux emulated the _r_debug structure, normally
maintained by ld.so, but that cannot be done in SGX outer PAL,
because it's loaded by ld.so already.
- Maintain the debug maps outside of SGX enclave. This allows
initializing them before enclave start, and potentially makes
them easier to use.
- Initialize PAL debug map before enclave start. Previously, this
was done from inside the enclave, so you couldn't set a
breakpoint too early (e.g. in pal_linux_main).
- Store only load address, without list of sections. This is to
avoid parsing the list of sections just to report them to the
debugger. Unfortunately, the GDB version that we support still
needs these sections, but we can retrieve them in GDB plugin.
- Move Python GDB code related to debug maps to a common file.
Applications under native/ cannot be run after commit "Introduce one,
central manifest, zero-config children and constant MRENCLAVE". Instead
of fixing native/, this commit simply moves helloworld and all its
mentions under regression/.
This is the next part of the great loader rework, with a lot of breaking changes:
- Complete removal of the "trusted children" thing - now children
processes can be spawned arbitrarily and from arbitrary mountpoint
types, without any additional configuration needed.
- There's a new, required option in the manifest: `libos.entrypoint` - it
specifies the URI to the entry binary in the first process. There's no
need anymore to name the manifest and the first binary identically.
- On SGX, the main binary is not measured in MRENCLAVE anymore - only
PAL, LibOS and the manifest are measured. This is enough to bind
MRENCLAVE to a specific entrypoint user executable if wanted - it
just has to be mounted as a trusted file.
- All Graphene SGX enclaves have now exactly the same MRENCLAVE. This is
a hash of a "Graphene stub", which can "fork" into one of two states
in runtime: initial process or child. The initial process creates a
new "Graphene namespace" with a clean state, it can also be attested
remotely (contrary to child processes). The initial process can spawn
children processes by spawning a Graphene stub and directing it to
start in the child mode. It then attests it locally, and if
successful, establishes an encrypted pipe, "connects" to its own
namespace and treats as trusted (including sending protected files
key).
- Now, there's only one, central manifest describing the initial state
of a Graphene instance which can be spawned from it (previously, each
process required a separate manifest which could have different
configuration - which wasn't actually supported and didn't make sense
design-wise). One downside of central manifests is that all processes
require the same enclave configuration (e.g. size), but that was
already the case so far because of broken checkpointing code. Also,
this is only a temporary problem, which will cease to exist after the
introduction of EDMM.
- `sgx.static_address` was renamed to `sgx.nonpie_binary` and now has to
be inserted manually by users (`sgx_sign` tools doesn't know about the
binaries run inside, which can be even provided or generated in
runtime by the user's workload).
- Caveat: the memory gap for non-PIE executables was removed because it
requires adding a new option to the manifest to be cleanly
implemented. This is left for some future loader rework PR.
This function was empty and it is responsibility of the caller (Pal
level) of specific exception handling function (LibOS level) to return
from the exception.
The profiling system instruments the asynchronous enclave exit
(AEX). Depending on configuration, we either snapshot the IP
value, or dump registers and (portion of) stack. The 'perf report'
tool can be used to generate a report from the samples.
This is a major refactor of the way manifests are loaded and handled,
which will be followed by a complete rework of the loader code (which
will include e.g. centralized config).
Changes/fixes:
- Huge part of manifest handling was refactored and untangled.
- Starting without a manifest is now disallowed. This was actually
accidentally broken for some time and no one complained. It also makes
little sense in practice and in Graphene's overall design, e.g. it
conflicts with protected argv.
- Now we only allow starting by giving the executable, not manifest (the
magic resolution logic was removed).
- Now manifests are sent over pipes between parent and children, instead
of children finding and loading them on their own. This is a
preparation for the upcoming centralized manifests change.
- Previously manifests were parsed 2 times on Linux and 3 times on
Linux-SGX (by untrusted PAL, trusted PAL and LibOS). This is now
fixed.
- The common `pal_main()` now requires that the backend-specific PAL
loader loads the manifest before calling it. SGX code already has to
do it (for proper initialization), so let's unify this interface for
all PALs.
- Fix for a PAL crash when manifest size was divisible by page size
(sic!). NULL termination was missing, but most of the time the padding
to page size saved Graphene from crashing.
Instead of using S_I* flags, or hardcoded octal literals, use
helpers such as PERM_rwxrwxr_x. These are proposed in a Linux patch
by Ingo Molnar: https://lwn.net/Articles/696231/
Logging to file was broken, because the PAL file write operation
required the user to provide an absolute offset, and LibOS always
provided an offset of 0. This worked when logging to stdout, but
in case of a regular file, it kept overwriting the beginning of
file.
To fix that, we introduce a a special DkDebugLog call. This is a
better solution than tracking the file offset manually, because
the offset would need to be synchronized across different threads
and processes, and debug logs should be as simple as possible. At
the same time, we don't want PAL to provide a generic "append to
a file" mechanism, because it makes I/O less deterministic.
The manifest syntax stays exactly the same, including 0 and 1
integers to denote boolean values (this is done for ease of porting
and can be fixed in future commits). The only visible change is
surrounding strings in the manifest with quotes (requirement of
TOML). All manifests and Makefiles of our tests and example apps are
ported to the new TOML syntax. Documentation is updated.
Previously, Graphene assumed that if it was built with the DCAP
SGX driver or in-kernel SGX driver, then it should use DCAP/ECDSA
based attestation. In fact, the SGX driver has nothing to do with
the attestation scheme. This commit allows to use EPID based
attestation even when Graphene is built with the DCAP SGX driver.
Previously, it was possible to use Graphene without the main executable
(e.g. having only preloaded libraries). We aren't aware of anyone using
this weird option, but worse, it led to a very bad UX when the user made
mistakes - e.g. having a typo in the manifest or executable name could
lead to Graphene starting without errors, but doing nothing.
Supporting these options complicates the design of Graphene and loading
logic significantly, providing little useful functionality:
- loader.exec:
- the main user of it were our tests
- worked only for the first process spawned inside Graphene, as it
was a unidirectional manifest->binary mapping, so the child
process didn't know about the corresponding manifest.
- sgx.sigfile:
- probably all existing usages of it were completely redundant
- was resolved relatively to CWD instead of the executable location,
which made it mostly useless
From now on, the correct location of the files is:
- either place the manifest and sigfile next to the binary, with a
matching name, or
- create a symlink to the binary in the folder where manifests are
stored and launch it through this symlink
The manifest option "sgx.allow_file_creation" is useless (most
real-world apps will set it to "1" anyway). So this commit simply
removes this option and always allows to create files.
Previously, Graphene preallocated 64MB for PAL internal metadata
like trusted/protected files metadata, handles metadata, etc.
If this limit was depleted, Graphene loudly failed, and the user
had no option but to change constant in source code and rebuild
Graphene. This commit adds the manifest option
`loader.pal_internal_mem_size` to allow increasing this limit.
This commit removes some unused code from LibOS, the biggest part of
which being the support for "inline" binaries linked directly against
LibOS.
This allows us to remove e.g. POINTER_TYPE() macro, which was supposed
to check if a type is a pointer type, but implemented the check based
only on the first 2 characters of the type name (?!?).
Previous iterations of GSC always built the Graphene runtime as part of
the `gsc build` command. This commit adds an option to extract the
compilation of the Graphene runtime from the GSC build command into a
separate command called `gsc build-graphene`. Using `gsc build-graphene`,
one can prepare a Docker image that includes the required runtime files
for a `gsc build` command.
The purpose of this separation is to publish Graphene Docker images for
special environments such as cloud environments. This simplifies the
configuration parameters for the user, since they only have to specify
the Graphene Docker image name instead of the Graphene repository and
Driver details.
When building graphenized Docker image, some build-time variables
like http_proxy, https_proxy, no_proxy must be specified (for
private network behind proxy). This commit adds `--build-arg` via
GSC_BUILD_FLAGS.
Michał Kowalczyk