Instead of the ever-messier text parsing of the output of the readelf
tool (which is clearly meant for human consumption not to be machine
parseable), parse the ELF binaries directly.
Add a small dependency-less ELF parser specific to the checks.
This is slightly more secure, too, because it removes potential
ambiguity due to misparsing and changes in the output format of `elfread`. It
also allows for stricter and more specific ELF format checks in the future.
This removes the build-time dependency for `readelf`.
It passes the test-security-check for me locally, though I haven't
checked on all platforms.
Debian 8 (Jessie) has:
- g++ version 4.9.2
- libc version 2.19
Ubuntu 16.04.4 (Xenial) has:
- g++ version 5.3.1
- libc version 2.23.0
CentOS 7 has:
- g++ version 4.8.5
- libc version 2.17
Taking the minimum of these as our target.
According to the GNU ABI document this corresponds to:
- GCC 4.8.5: GCC_4.8.0
- (glibc) GLIBC_2_17
Co-Authored-By: fanquake <fanquake@gmail.com>
Flagged by flake8 v3.6.0, as W605, plus a few others identified
incidentally, e.g. 59ffecf66cf4d08c4b431e457b083878d66a3fd6.
Note that r"\n" matches to "\n" under re.match/search.
Ubuntu 16.04 "xenial xerus" does not come with Python 2.x by default.
It is possible to install a python-2.7 package, but this has its own
problem: no `python` or `python2` symlink (see #7717).
This fixes the following scripts to work with python 3:
- `make check` (bctest,py, bitcoin-util-test.py)
- `make translate` (extract_strings_qt.py)
- `make symbols-check` (symbol-check.py)
- `make security-check` (security-check.py)
Explicitly call the python commands using $(PYTHON) instead
of relying on the interpreter line at the top of the scripts.
Perform the following ELF security checks:
- PIE: Check for position independent executable (PIE), allowing for address space randomization
- NX: Check that no sections are writable and executable (including the stack)
- RELRO: Check for read-only relocations, binding at startup
- Canary: Check for use of stack canary
Also add a check to symbol-check.py that checks that only the subset of
allowed libraries is imported (to avoid incompatibilities).
Add a script to check that the (Linux) executables produced by gitian
only contain allowed gcc, glibc and libstdc++ version symbols. This
makes sure they are still compatible with the minimum supported Linux
distribution versions.
Wladimir J. van der Laan