NAME¶

Trinity - Linux system call fuzzer

DESCRIPTION¶

"After the initial euphoria of witnessing the explosion had passed, test director Kenneth Bainbridge commented to Los Alamos director J. Robert Oppenheimer, "Now we are all sons of bitches." Oppenheimer later stated that while watching the test he was reminded of a line from the Hindu scripture the Bhagavad Gita:

Now I am become Death, the destroyer of worlds."

SYNOPSIS¶

System call fuzzers aren't a particularly new idea. As far back as 1991, people have written apps that bomb syscall inputs with garbage data, that have had a variety of success in crashing assorted operating systems.

After fixing the obvious dumb bugs however, a majority of the time these calls will just by rejected by the kernel very near the beginning of their function entry point as basic parameter validation is performed.

Trinity is a system call fuzzer which employs some techniques to pass semi-intelligent arguments to the syscalls being called.

The intelligence features include:

- If a system call expects a certain datatype as an argument
(for example a file descriptor) it gets passed one.
This is the reason for the slow initial startup, as it generates a
list of fd's of files it can read from /sys, /proc and /dev
and then supplements this with fd's for various network protocol sockets.
(Information on which protocols succeed/fail is cached on the first run,
greatly increasing the speed of subsequent runs).

- If a system call only accepts certain values as an argument,
(for example a 'flags' field), trinity has a list of all the valid
flags that may be passed.
Just to throw a spanner in the works, occasionally, it will bitflip
one of the flags, just to make things more interesting.

- If a system call only takes a range of values, the random value
passed is biased to usually fit within that range.

Trinity logs it's output to a files (1 for each child process), and fsync's the files before it actually makes the system call. This way, should you trigger something which panics the kernel, you should be able to find out exactly what happened by examining the log.

There are several test harnesses provided (test-*.sh), which run trinity in various modes and takes care of things like cpu affinity, and makes sure it runs from the tmp directory. (Handy for cleaning up any garbage named files; just rm -rf tmp afterwards)

OPTIONS¶

--arch -a

Selects syscalls for the specified architecture (32 or 64). Both by default.

--bdev -b <node>

Add dev node to list of block devices to use for destructive tests.

--children -C

Specify number of child processes

--debug -D

Enable debug

--dropprivs -X

If run as root, switch to nobody [EXPERIMENTAL]

--exclude -x

Don't call a specific syscall

--enable-fds or --disable-fds

Options are: sockets, pipes, perf, epoll, eventfd, pseudo, timerfd, testfile, memfd and drm

--group -g = {vfs,vm}

Only run syscalls from a certain group.

--ioctls -I

List all ioctls.

--kernel_taint -T

Controls which kernel taint flags should be considered.

--list -L

List all syscalls known on this architecture.

--logging -l

off=disable logging. <dirname> specify a directory where logfiles will be placed.

--domain -P

Specify specific network domain for sockets.

--no_domain -E

Specify network domains to be excluded from testing.

--quiet -q

Less output.

--random -r#

Pick N syscalls at random and just fuzz those

--syslog -S

Log important info to syslog. Useful if syslog is remote.

--verbose -v

Increase output verbosity.

--victims -V

Path to victim files.

-c# @

Target specific syscall, takes syscall name as parameter and optionally 32 or 64 as bit-width. Default is both.

-N#

Do # syscalls then exit.

-p

Pause after syscall.

-s#

use # as random seed.

EXAMPLES¶

trinity -c splice

Stress test the splice syscall

trinity -x splice

Call every syscall except for splice.

trinity -qq -l off -C16

Turn off logging, and suppress most output to run as fast as possible. Use 16 child processes

AUTHOR¶

Trinity is written by Dave Jones <davej@codemonkey.org.uk>