fcd2d5a612
Previously, the API version limit was indicated with a numeric version
number. This was "natural" in the pre-3.0.0 because the version was
this simple number.
With 3.0.0, the version is divided into three separate numbers, and
it's only the major number that counts, but we still need to be able
to support pre-3.0.0 version limits.
Therefore, we allow OPENSSL_API_COMPAT to be defined with a pre-3.0.0
style numeric version number or with a simple major number, i.e. can
be defined like this for any application:
-D OPENSSL_API_COMPAT=0x10100000L
-D OPENSSL_API_COMPAT=3
Since the pre-3.0.0 numerical version numbers are high, it's easy to
distinguish between a simple major number and a pre-3.0.0 numerical
version number and to thereby support both forms at the same time.
Internally, we define the following macros depending on the value of
OPENSSL_API_COMPAT:
OPENSSL_API_0_9_8
OPENSSL_API_1_0_0
OPENSSL_API_1_1_0
OPENSSL_API_3
They indicate that functions marked for deprecation in the
corresponding major release shall not be built if defined.
Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7724)
|
||
|---|---|---|
| .. | ||
| corpora | ||
| asn1.c | ||
| asn1parse.c | ||
| bignum.c | ||
| bndiv.c | ||
| build.info | ||
| client.c | ||
| cms.c | ||
| conf.c | ||
| crl.c | ||
| ct.c | ||
| driver.c | ||
| fuzzer.h | ||
| helper.py | ||
| mkfuzzoids.pl | ||
| oids.txt | ||
| rand.inc | ||
| README.md | ||
| server.c | ||
| test-corpus.c | ||
| x509.c | ||
I Can Haz Fuzz?
LibFuzzer
Or, how to fuzz OpenSSL with libfuzzer.
Starting from a vanilla+OpenSSH server Ubuntu install.
Use Chrome's handy recent build of clang. Older versions may also work.
$ sudo apt-get install git
$ mkdir git-work
$ git clone https://chromium.googlesource.com/chromium/src/tools/clang
$ clang/scripts/update.py
You may want to git pull and re-run the update from time to time.
Update your path:
$ PATH=~/third_party/llvm-build/Release+Asserts/bin/:$PATH
Get and build libFuzzer (there is a git mirror at https://github.com/llvm-mirror/llvm/tree/master/lib/Fuzzer if you prefer):
$ cd
$ sudo apt-get install subversion
$ mkdir svn-work
$ cd svn-work
$ svn co https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer Fuzzer
$ cd Fuzzer
$ clang++ -c -g -O2 -std=c++11 *.cpp
$ ar r libFuzzer.a *.o
$ ranlib libFuzzer.a
Configure for fuzzing:
$ CC=clang ./config enable-fuzz-libfuzzer \
--with-fuzzer-include=../../svn-work/Fuzzer \
--with-fuzzer-lib=../../svn-work/Fuzzer/libFuzzer.a \
-DPEDANTIC enable-asan enable-ubsan no-shared \
-DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION \
-fsanitize-coverage=trace-pc-guard,indirect-calls,trace-cmp \
enable-ec_nistp_64_gcc_128 -fno-sanitize=alignment enable-tls1_3 \
enable-weak-ssl-ciphers enable-rc5 enable-md2 \
enable-ssl3 enable-ssl3-method enable-nextprotoneg \
--debug
$ sudo apt-get install make
$ LDCMD=clang++ make -j
$ fuzz/helper.py $FUZZER
Where $FUZZER is one of the executables in fuzz/.
If you get a crash, you should find a corresponding input file in
fuzz/corpora/$FUZZER-crash/.
AFL
Configure for fuzzing:
$ sudo apt-get install afl-clang
$ CC=afl-clang-fast ./config enable-fuzz-afl no-shared -DPEDANTIC \
enable-tls1_3 enable-weak-ssl-ciphers enable-rc5 enable-md2 \
enable-ssl3 enable-ssl3-method enable-nextprotoneg \
enable-ec_nistp_64_gcc_128 -fno-sanitize=alignment \
--debug
$ make
The following options can also be enabled: enable-asan, enable-ubsan, enable-msan
Run one of the fuzzers:
$ afl-fuzz -i fuzz/corpora/$FUZZER -o fuzz/corpora/$FUZZER/out fuzz/$FUZZER
Where $FUZZER is one of the executables in fuzz/.
Reproducing issues
If a fuzzer generates a reproducible error, you can reproduce the problem using the fuzz/-test binaries and the file generated by the fuzzer. They binaries don't need to be build for fuzzing, there is no need to set CC or the call config with enable-fuzz- or -fsanitize-coverage, but some of the other options above might be needed. For instance the enable-asan or enable-ubsan option might be useful to show you when the problem happens. For the client and server fuzzer it might be needed to use -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION to reproduce the generated random numbers.
To reproduce the crash you can run:
$ fuzz/$FUZZER-test $file
Random numbers
The client and server fuzzer normally generate random numbers as part of the TLS connection setup. This results in the coverage of the fuzzing corpus changing depending on the random numbers. This also has an effect for coverage of the rest of the test suite and you see the coverage change for each commit even when no code has been modified.
Since we want to maximize the coverage of the fuzzing corpus, the client and server fuzzer will use predictable numbers instead of the random numbers. This is controlled by the FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION define.
The coverage depends on the way the numbers are generated. We don't disable any check of hashes, but the corpus has the correct hash in it for the random numbers that were generated. For instance the client fuzzer will always generate the same client hello with the same random number in it, and so the server, as emulated by the file, can be generated for that client hello.
Coverage changes
Since the corpus depends on the default behaviour of the client and the server, changes in what they send by default will have an impact on the coverage. The corpus will need to be updated in that case.
Updating the corpus
The client and server corpus is generated with multiple config options:
- The options as documented above
- Without enable-ec_nistp_64_gcc_128 and without --debug
- With no-asm
- Using 32 bit
- A default config, plus options needed to generate the fuzzer.
The libfuzzer merge option is used to add the additional coverage from each config to the minimal set.