Add "untrusted" sections for environment variables defined in Occlum.json. Environment
variable defined in "default" will be shown in libos directly. Environment variable
defined in "untrusted" can be passed from occlum run or PAL layer and can override
the value in "default" and thus is considered "untrusted".
In this commit, we add eight signal-related syscalls
* kill
* tkill
* tgkill
* rt_sigaction
* rt_sigreturn
* rt_sigprocmask
* rt_sigpending
* exit_group
We implement the following major features for signals:
* Generate, mask, and deliver signals
* Support user-defined signal handlers
* Support nested invocation of signal handlers
* Support passing arguments: signum, sigaction, and ucontext
* Support both process-directed and thread-directed signals
* Capture hardware exceptions and convert them to signals
* Deliver fatal signals (like SIGKILL) to kill processes gracefully
But we still have gaps, including but not limited to the points below:
* Convert #PF (page fault) and #GP (general protection) exceptions to signals
* Force delivery of signals via interrupt
* Support simulation mode
1. All generated, build files are now in a separate build directory;
2. The CLI tool supports three sub-commands: init, build, and run;
3. Refactor tests to use the new tool.
* Add patch to Rust SGX SDK to enable integrity-only SgxFile
* Upgrade to the new SEFS extended with the integrity-only mode
* Use integrity-only SEFS for /bin and /lib in test
* Add the MAC of integrity-only SEFS to Occlum.json in test
* Mount multiple FS according to Occlum.json
* Check the MACs of integrity-only SEFS images
The old system call mechanism works by relocating the symbol __occlum_syscall
provided by libocclum_stub.so to the real entry point of the LibOS. This symbol
relocation is done by the program loader. Now, the new system call mechanism is
based on passing the entry point via the auxiliary vector. This new mechanism
is simpler and is more compatible with the upcoming support for ld.so.
Changes:
1. Fix a bug in serializing auxiliary vector in the stack of a user program;
2. Passing syscall entry via auxiliary vector;
3. Remove relocating for the __occlum_syscall symbol;
4. Remove the dependency on libocclum_stub.so in tests.
