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.
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 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.
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.
Applications tend to use `/proc/cpuinfo` to get the `cpu cores`
and `physical id` for computing number of physical cores in a
socket. Currently `cpu cores` field is incorrectly implemented as
it is set to number of logical processors online and `physical id`
isn't implemented. This patch addresses both of these issues.
Plenty of bugfixes for Linux kernel later than 3.5 and Ubuntu later than 10.10.
More organized code to improve portability.
Regression tests for Pal to test completeness of implementation.
borysp