Add a libfuzz[1] based fuzzer testing the reading and parsing of binary policy
files. This fuzzer will be run within the OSS-Fuzz service.
Handle and reject a variety of edge cases causing crashes or resource leaks.
The fifth patch ("libsepol/fuzz: limit element sizes for fuzzing") needs some
discussion: To avoid oom reports from the fuzzer, caused by huge memory
allocations, all identifiers are limited to a length of 2^16 for the fuzzer
build only. Probably there should be a limit for the release build too.
Is there a specification for the binary policy format saying something about
the maximum length of identifiers?
After a quick look at the kernel sources (most interesting is str_read()) I
could not find any limits either.
[1]: https://llvm.org/docs/LibFuzzer.html
Christian Göttsche (35):
cifuzz: enable report-unreproducible-crashes
cifuzz: use the default runtime of 600 seconds
libsepol/fuzz: silence secilc-fuzzer
libsepol: add libfuzz based fuzzer for reading binary policies
libsepol/fuzz: limit element sizes for fuzzing
libsepol: use logging framework in conditional.c
libsepol: use logging framework in ebitmap.c
libsepol: use mallocarray wrapper to avoid overflows
libsepol: use reallocarray wrapper to avoid overflows
libsepol: add checks for read sizes
libsepol: enforce avtab item limit
libsepol: clean memory on conditional read failure
libsepol: validate MLS levels
libsepol: reject invalid fsuse types
libsepol: reject invalid default targets
libsepol: validate expanded user range and level
libsepol: validate types
libsepol: use size_t for indexes in strs helpers
libsepol: reject abnormal huge sid ids
libsepol: do not crash on class gaps
libsepol: do not crash on user gaps
libsepol: validate permission count of classes
libsepol: resolve log message mismatch
libsepol: zero member before potential dereference
libsepol: validate avtab types
libsepol: validate constraint expression operators and attributes
libsepol: validate type of avtab type rules
libsepol: validate ocontexts
libsepol: validate genfs contexts
libsepol: validate permissive types
libsepol: validate policy properties
libsepol: do not underflow on short format arguments
libsepol: validate categories
libsepol: use correct size for initial string list
libsepol: do not create a string list with initial size zero
.github/workflows/cifuzz.yml | 3 +-
libsepol/fuzz/binpolicy-fuzzer.c | 63 +++++++
libsepol/fuzz/policy.bin | Bin 0 -> 1552 bytes
libsepol/fuzz/secilc-fuzzer.c | 5 +
libsepol/src/Makefile | 6 +
libsepol/src/avtab.c | 6 +
libsepol/src/conditional.c | 36 ++--
libsepol/src/ebitmap.c | 27 ++-
libsepol/src/expand.c | 4 +-
libsepol/src/hashtab.c | 4 +-
libsepol/src/kernel_to_cil.c | 10 ++
libsepol/src/kernel_to_common.c | 23 ++-
libsepol/src/kernel_to_common.h | 4 +-
libsepol/src/kernel_to_conf.c | 13 +-
libsepol/src/link.c | 3 +-
libsepol/src/module.c | 4 +-
libsepol/src/module_to_cil.c | 13 +-
libsepol/src/optimize.c | 11 +-
libsepol/src/policydb.c | 68 +++++++-
libsepol/src/policydb_validate.c | 274 +++++++++++++++++++++++++++++--
libsepol/src/private.h | 27 ++-
libsepol/src/services.c | 12 +-
libsepol/src/sidtab.c | 3 +-
libsepol/src/user_record.c | 8 +-
libsepol/src/users.c | 12 +-
libsepol/src/util.c | 11 +-
libsepol/src/write.c | 2 +-
scripts/oss-fuzz.sh | 19 ++-
28 files changed, 556 insertions(+), 115 deletions(-)
create mode 100644 libsepol/fuzz/binpolicy-fuzzer.c
create mode 100644 libsepol/fuzz/policy.bin
--
2.33.0
