Ubuntu Manpage: libzzuf - helper library for the zzuf multiple purpose fuzzer

NAME

       libzzuf - helper library for the zzuf multiple purpose fuzzer

DESCRIPTION

       libzzuf is a helper library automatically preloaded by zzuf when fuzzing applications, but it can also be
       used alone for debugging purposes or specific cases that cannot be covered by zzuf.

USAGE

       libzzuf must be preloaded using the operating system's default way of preloading libraries. For instance,
       on a typical Linux installation:

           LD_PRELOAD=/usr/lib/zzuf/libzzuf.so

ENVIRONMENT VARIABLES

libzzuf's initial setup is done through environment variables. After they are read, no further
information can be sent to the fuzzed process.

All environment variables are optional.

ZZUF_DEBUG
This environment variable is set to the debugging level. 0 means no debugging information is sent
to zzuf. 1 logs important information as well as all diverted functions. 2 logs fuzzing status and
all optional file stream information.

ZZUF_DEBUGFD
This environment variable is set to a file descriptor where libzzuf will send debugging
information. This is used to send data to the main zzuf controlling binary.

ZZUF_SEED
This variable is set to the initial random seed. Corresponding zzuf flag: --seed.

ZZUF_MINRATIO, ZZUF_MAXRATIO
These variables are set to the minimal and maximal fuzzing ratios. Corresponding zzuf flag:
--ratio.

ZZUF_AUTOINC
If this variable is set, the random seed is incremented each time a new file is opened.
Corresponding zzuf flag: --autoinc.

ZZUF_BYTES
This variable contains byte ranges to which fuzzing should be restricted. Corresponding zzuf
flag: --bytes.

ZZUF_LIST
This variable contains file descriptor ranges to which fuzzing should be restricted. Corresponding
zzuf flag: --list.

ZZUF_NETWORK
If this variable is set, network mode is activated. Corresponding zzuf flag: --network.

ZZUF_PORTS
This variable contains port ranges to which fuzzing should be restricted. Corresponding zzuf
flag: --port.

ZZUF_PROTECT, ZZUF_REFUSE
These variables contain character ranges to protect or refuse. Corresponding zzuf flags:
--protect, --refuse.

ZZUF_INCLUDE, ZZUF_EXCLUDE
These variables contain regular expressions to indicate which files should be included or excluded
from the list of fuzzed files. Corresponding zzuf flags: --include, --exclude.

ZZUF_SIGNAL
If this variable is set, the fuzzed process will be prevented from installing signal handlers that
usually cause coredumps. Corresponding zzuf flag: --signal.

ZZUF_MEMORY
This variable contains the maximum amount of memory that the fuzzed process is allowed to
allocate. Corresponding zzuf flag: --max-memory.

ZZUF_STDIN
If this variable is set, standard input will be fuzzed, too. Corresponding zzuf flag: --stdin.

NOTES

       In order to intercept file and network  operations,  signal  handlers  and  memory  allocations,  libzzuf
       diverts and reimplements the following functions, which can sometimes be private C library symbols, too:

       Unix file descriptor handling:
              open(),  dup(), dup2(), lseek(), read(), readv(), pread(), accept(), socket(), recv(), recvfrom(),
              recvmsg(), aio_read(), aio_return(), close()

       Standard IO streams:
              fopen(), freopen(), fseek(), fseeko(), rewind(), fread(),  getc(),  getchar(),  fgetc(),  fgets(),
              ungetc(), fclose()

       Memory management:
              mmap(), munmap(), malloc(), calloc(), valloc(), free(), memalign(), posix_memalign()

       Required on Linux:
              open64(),  lseek64(),  mmap64(), _IO_getc(), getline(), getdelim(), __getdelim(), getc_unlocked(),
              getchar_unlocked(), fgetc_unlocked(), fgets_unlocked(), fread_unlocked(), __uflow()

       Required on BSD systems:
              fgetln(), __srefill(), __srget()

       Required on Mac OS X:
              map_fd()

       Required on HP-UX:
              __open64(), __lseek64(), __filbuf()

       Required on OpenSolaris:
              freopen64(), fseeko64(), fsetpos64()

       Signal handling:
              signal(), sigaction()

       If an application manipulates file descriptors (reading data, seeking around) using  functions  that  are
       not in that list, libzzuf will not fuzz its input consistently and the results should not be trusted. You
       can use a tool such as ltrace(1) on Linux to know the missing functions.

       On  BSD  systems,  such  as FreeBSD or Mac OS X, __srefill() is enough to monitor all standard IO streams
       functions. On other systems, such as Linux, each function is reimplemented on a case by case  basis.  One
       important  unimplemented function is fscanf(), because of its complexity. Missing functions will be added
       upon user request.

AUTHOR