[LTP] [PATCH v2] Wrapper for Syzkaller reproducers
Richard Palethorpe
rpalethorpe@suse.de
Wed Feb 19 09:27:51 CET 2020
Hello Dmitry,
Dmitry Vyukov via ltp <ltp@lists.linux.it> writes:
> On Wed, Dec 4, 2019 at 11:31 AM Richard Palethorpe <rpalethorpe@suse.com> wrote:
>>
>> Allows one to run the Syzkaller reproducers as part of the LTP.
>>
>> Signed-off-by: Richard Palethorpe <rpalethorpe@suse.com>
>> ---
>>
>> V2:
>>
>> * Will now refuse to compile on anything other than x86_64, because I haven't
>> tested them on anything else.
>>
>> * Hopefully fixed problem with submodule not being found because I didn't
>> include a commit reference.
>>
>> * Added explicity 'no' value if --with-syzkaller-repros is not present
>>
>> * Reduced the default timeout in the test to 20 seconds. I found this allows
>> me to complete testing in reasonable time.
>
> What's the status of this? This wasn't merged yet, right?
> I don't see this here:
> https://github.com/linux-test-project/ltp/tree/master/testcases/kernel
Yeah, it fell to one side due to the LTP release, SUSE Hackweek and lack
of feedback. Hopefully we can get it merged soon however.
>
> People are asking how these tests can be run:
> https://github.com/dvyukov/syzkaller-repros/pull/1#issuecomment-583996369
I responded with some links for using it.
>
>
>> .gitmodules | 4 +
>> configure.ac | 12 ++
>> include/mk/features.mk.in | 2 +
>> runtest/.gitignore | 1 +
>> testcases/kernel/Makefile | 1 +
>> testcases/kernel/syzkaller-repros/.gitignore | 1 +
>> testcases/kernel/syzkaller-repros/Makefile | 105 +++++++++++++++
>> testcases/kernel/syzkaller-repros/README.md | 45 +++++++
>> testcases/kernel/syzkaller-repros/syzwrap.c | 134 +++++++++++++++++++
>> testcases/linux-arts | 1 +
>> 10 files changed, 306 insertions(+)
>> create mode 100644 runtest/.gitignore
>> create mode 100644 testcases/kernel/syzkaller-repros/.gitignore
>> create mode 100644 testcases/kernel/syzkaller-repros/Makefile
>> create mode 100644 testcases/kernel/syzkaller-repros/README.md
>> create mode 100644 testcases/kernel/syzkaller-repros/syzwrap.c
>> create mode 160000 testcases/linux-arts
>>
>> diff --git a/.gitmodules b/.gitmodules
>> index 1c9e9c38a..2b9e836e6 100644
>> --- a/.gitmodules
>> +++ b/.gitmodules
>> @@ -1,3 +1,7 @@
>> [submodule "testcases/kernel/mce-test"]
>> path = testcases/kernel/mce-test
>> url = git://git.kernel.org/pub/scm/linux/kernel/git/gong.chen/mce-test.git
>> +[submodule "testcases/linux-arts"]
>> + path = testcases/linux-arts
>> + url = https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-arts.git
>> + shallow = true
>> diff --git a/configure.ac b/configure.ac
>> index 50d14967d..c8ae42121 100644
>> --- a/configure.ac
>> +++ b/configure.ac
>> @@ -187,6 +187,18 @@ else
>> AC_SUBST([WITH_OPEN_POSIX_TESTSUITE],["no"])
>> fi
>>
>> +AC_ARG_WITH([syzkaller-repros],
>> + [AC_HELP_STRING([--with-syzkaller-repros],
>> + [compile and install Syzkaller reproducers (default=no)])],
>> + [with_syzkaller_repros=$withval]
>> + [with_syzkaller_repros=no]
>> +)
>> +if test "x$with_syzkaller_repros" = xyes; then
>> + AC_SUBST([WITH_SYZKALLER_REPROS],["yes"])
>> +else
>> + AC_SUBST([WITH_SYZKALLER_REPROS],["no"])
>> +fi
>> +
>> # TODO: testcases/realtime requires bash and python.
>> AC_ARG_WITH([realtime-testsuite],
>> [AC_HELP_STRING([--with-realtime-testsuite],
>> diff --git a/include/mk/features.mk.in b/include/mk/features.mk.in
>> index 8e561b738..3ab7f4721 100644
>> --- a/include/mk/features.mk.in
>> +++ b/include/mk/features.mk.in
>> @@ -47,3 +47,5 @@ WITH_REALTIME_TESTSUITE := no
>> else
>> WITH_REALTIME_TESTSUITE := @WITH_REALTIME_TESTSUITE@
>> endif
>> +
>> +WITH_SYZKALLER_REPROS := @WITH_SYZKALLER_REPROS@
>> diff --git a/runtest/.gitignore b/runtest/.gitignore
>> new file mode 100644
>> index 000000000..2ae05bfac
>> --- /dev/null
>> +++ b/runtest/.gitignore
>> @@ -0,0 +1 @@
>> +syzkaller*
>> diff --git a/testcases/kernel/Makefile b/testcases/kernel/Makefile
>> index 3319b3163..0150cfb4f 100644
>> --- a/testcases/kernel/Makefile
>> +++ b/testcases/kernel/Makefile
>> @@ -53,6 +53,7 @@ SUBDIRS += connectors \
>> sched \
>> security \
>> sound \
>> + syzkaller-repros \
>> tracing \
>> uevents \
>>
>> diff --git a/testcases/kernel/syzkaller-repros/.gitignore b/testcases/kernel/syzkaller-repros/.gitignore
>> new file mode 100644
>> index 000000000..dbda1c71f
>> --- /dev/null
>> +++ b/testcases/kernel/syzkaller-repros/.gitignore
>> @@ -0,0 +1 @@
>> +syzwrap
>> diff --git a/testcases/kernel/syzkaller-repros/Makefile b/testcases/kernel/syzkaller-repros/Makefile
>> new file mode 100644
>> index 000000000..a3acf9647
>> --- /dev/null
>> +++ b/testcases/kernel/syzkaller-repros/Makefile
>> @@ -0,0 +1,105 @@
>> +# SPDX-License-Identifier: GPL-2.0-or-later
>> +# Copyright (c) 2019 Linux Test Project
>> +
>> +top_srcdir ?= ../../..
>> +
>> +include $(top_srcdir)/include/mk/testcases.mk
>> +
>> +CFLAGS += -D_GNU_SOURCE
>> +
>> +ifeq ($(WITH_SYZKALLER_REPROS),yes)
>> +
>> +# This is mainly due to the -m32 flag, but there could be other problems.
>> +ifneq ($(HOST_CPU), x86_64))
>> +$(error "We currently only support building the Syzkaller reproducers on x86_64")
>> +endif
>> +
>> +# The number of reproducers in each runtest file
>> +SYZKALLER_RUNFILES_SIZE ?= 100
>> +
>> +# Extra arguments to pass to syzwrap. Uncomment the below to add some
>> +# sandboxing.
>> +# SYZWRAP_ARGS ?= -s
>> +
>> +# Location where reproducers are installed
>> +SYZKALLER_INSTALL_DIR ?= $(abspath $(DESTDIR)/$(prefix)/testcases/bin)
>> +
>> +# If the reproducers directory is missing then we automatically clone the repo.
>> +# We then have to call make recursively to revaluate the targets
>> +SYZKALLER_REPROS_DIR ?= $(abs_top_srcdir)/testcases/linux-arts/syzkaller-repros/linux
>> +$(SYZKALLER_REPROS_DIR):
>> + git submodule update --init $(abs_top_srcdir)/testcases/linux-arts
>> + $(MAKE) syzkaller_runfiles
>> +
>> +SYZKALLER_REPROS_SRCS = $(wildcard $(SYZKALLER_REPROS_DIR)/*.c)
>> +
>> +# Some useful compiler flags for the LTP will cause problems with the
>> +# syzkaller repros so the repros have seperate flags
>> +SYZKALLER_CFLAGS ?= -pthread
>> +SYZKALLER_REPROS = $(subst $(abs_top_srcdir),$(abs_top_builddir),$(SYZKALLER_REPROS_SRCS:.c=))
>> +$(SYZKALLER_REPROS): %: %.c
>> + -@if grep -q "__NR_mmap2" $^; then \
>> + M32="-m32"; \
>> + fi; \
>> + $(CC) $(SYZKALLER_CFLAGS) $$M32 $(SYZKALLER_LDFLAGS) $^ -o $@; \
>> + echo $(CC) $(SYZKALLER_CFLAGS) $$M32 $(SYZKALLER_LDFLAGS) $^ -o $@;
>> +
>> +# Generate the names of the runtest files. This uses Shell arithmetic to
>> +# calculate how many runtest files there will be.
>> +define SYZKALLER_RUNFILES !=
>> + n=$(words $(SYZKALLER_REPROS));
>> + m=$(SYZKALLER_RUNFILES_SIZE);
>> + i=$$(( $$n / $$m + ($$n % $$m > 0) ));
>> + while test $$i -gt 0;
>> + do
>> + echo $(top_srcdir)/runtest/syzkaller$$i;
>> + i=$$(($$i - 1));
>> + done
>> +endef
>> +
>> +# Get the index part of a runtest files name
>> +syz_n = $(subst $(top_srcdir)/runtest/syzkaller,,$(1))
>> +syz_m = $(SYZKALLER_RUNFILES_SIZE)
>> +# Gives the index of the first reproducer in a runtest file
>> +syz_i = $(shell echo $$((($(call syz_n,$(1)) - 1) * $(2) + 1)))
>> +# Gives the index of the last reproducer in a runtest file
>> +syz_j = $(shell echo $$(( $(call syz_i,$(1),$(2)) + $(2) - 1 )))
>> +# Gvien a runtest file name, get the reproducers it should contain
>> +syz_wordlist = $(wordlist $(call syz_i,$(1),$(syz_m)),$(call syz_j,$(1),$(syz_m)),$(SYZKALLER_REPROS))
>> +
>> +define syz_runfile_line
>> +$(notdir $(exe)) syzwrap $(SYZWRAP_ARGS) -d $(SYZKALLER_INSTALL_DIR) -n $(notdir $(exe))
>> +
>> +endef
>> +
>> +# Generate the runtest files based on the reproducer names and batch size.
>> +$(SYZKALLER_RUNFILES): $(SYZKALLER_REPROS)
>> + @echo "Writing $@"
>> + $(file >$@)
>> + $(foreach exe,$(call syz_wordlist,$@),$(file >>$@,$(syz_runfile_line)))
>> +
>> +.PHONY: syzkaller_runfiles
>> +syzkaller_runfiles: $(SYZKALLER_RUNFILES) | $(SYZKALLER_REPROS_DIR)
>> +
>> +all: $(SYZKALLER_RUNFILES) | $(SYZKALLER_REPROS_DIR)
>> +
>> +# There are too many reproducers to pass all at once to rm, so we just pass
>> +# one at a time
>> +syzkaller_clean:
>> + $(foreach f, $(SYZKALLER_REPROS), $(RM) $(f))
>> +CLEAN_DEPS += syzkaller_clean
>> +CLEAN_TARGETS += $(SYZKALLER_RUNFILES)
>> +
>> +INSTALL_MODE ?= 0775
>> +
>> +# For some reason part of the path is missing if we just try to install these
>> +# by adding them to INSTALL_FILES
>> +SYZKALLER_REPROS_INSTALLED := $(subst $(SYZKALLER_REPROS_DIR),$(SYZKALLER_INSTALL_DIR),$(SYZKALLER_REPROS))
>> +$(SYZKALLER_REPROS_INSTALLED): $(SYZKALLER_INSTALL_DIR)/%: $(SYZKALLER_REPROS_DIR)/%
>> + install -m $(INSTALL_MODE) -T $< $@
>> +
>> +install: $(SYZKALLER_REPROS_INSTALLED)
>> +
>> +endif
>> +
>> +include $(top_srcdir)/include/mk/generic_leaf_target.mk
>> diff --git a/testcases/kernel/syzkaller-repros/README.md b/testcases/kernel/syzkaller-repros/README.md
>> new file mode 100644
>> index 000000000..2c88efd01
>> --- /dev/null
>> +++ b/testcases/kernel/syzkaller-repros/README.md
>> @@ -0,0 +1,45 @@
>> +# LTP wrapper for Syzkaller reproducers
>> +
>> +This allows you to run the autogenerated C bug reproducers from the Syzkaller
>> +fuzzer within the LTP framework. Meaning that you may use an existing test
>> +runner compatible with the LTP (with some constraints, see below).
>> +
>> +## Instructions
>> +
>> +1. Run `ltp/configure` with `--with-syzkaller-repros`.
>> +2. Build and install the LTP as normal.
>> +3. Run one or more of syzkallerN runtest files where N is a number.
>> +
>> +Make will automatically download the reproducers into `testcases/linux-arts`
>> +using git-submodule if necessary.
>> +
>> +By default each runtest file contains 100 reproducers. You may change this by
>> +overriding `SYZKALLER_RUNFILES_SIZE`.
>> +
>> +Extra parameters can be sent to syzwrap using `SYZWRAP_ARGS`. See `syzwrap
>> +-h`.
>> +
>> +## Kernel Requirements
>> +
>> +It is strongly recommended that you use KASAN and other debugging kernel
>> +features. See the Syzkaller documentation for the configuration you should
>> +use.
>> +
>> +## Test Runner Requirements
>> +
>> +Unlike most LTP tests these reproducers can leave your system in a broken
>> +state even if no bug is triggered.
>> +
>> +You will need to:
>> +
>> +A) Reboot the SUT
>> +B) Reset at least the root filesystem to a known good state
>> +
>> +Every time syzwrap fails.
>> +
>> +If syzwrap fails with TBROK or fails to run at all, then you probably need to
>> +reset the system and rerun that test. If a test fails with TFAIL, you may also
>> +want to run it once again with a clean state.
>> +
>> +It might be the case that some reproducers write to random devices or do other
>> +things which can effect the outside world.
>> diff --git a/testcases/kernel/syzkaller-repros/syzwrap.c b/testcases/kernel/syzkaller-repros/syzwrap.c
>> new file mode 100644
>> index 000000000..c8c95e750
>> --- /dev/null
>> +++ b/testcases/kernel/syzkaller-repros/syzwrap.c
>> @@ -0,0 +1,134 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later
>> +/*
>> + * Copyright (c) 2019 Richard Palethorpe <rpalethorpe@suse.com>
>> + *
>> + * Run a single reproducer generated by the Syzkaller fuzzer.
>> + */
>> +
>> +#include <sys/types.h>
>> +#include <sys/wait.h>
>> +#include <sys/prctl.h>
>> +#include <sched.h>
>> +#include <signal.h>
>> +#include <stdio.h>
>> +#include <pwd.h>
>> +
>> +#include "tst_test.h"
>> +#include "tst_taint.h"
>> +#include "tst_safe_stdio.h"
>> +
>> +#define SANDBOX_HELP "\n"\
>> + "-s\t Add some sandboxing around the reproducer. This will prevent some\n"\
>> + "\t reproducers from creating network devices and thus prevent them from\n"\
>> + "\t working. However it will also prevent some reproducers from trashing\n"\
>> + "\t the system using root privileges. Note that you may generate the\n"\
>> + "\t reproducers with various types of sandboxing built in using\n"\
>> + "\t syz-reprolist"
>> +
>> +static char *dir;
>> +static char *name;
>> +static char *path;
>> +
>> +static char *sandbox;
>> +
>> +static struct tst_option options[] = {
>> + {"d:", &dir, "\n-d PATH\t Mandatory directory containing reproducers"},
>> + {"n:", &name, "-n NAME\t Mandatory executable name of reproducer"},
>> + {"s", &sandbox, SANDBOX_HELP},
>> + {NULL, NULL, NULL}
>> +};
>> +
>> +static void become_nobody(void)
>> +{
>> + struct passwd *pw;
>> + int gid, uid;
>> +
>> + setgroups(0, NULL);
>> +
>> + pw = getpwnam("nobody");
>> + if (pw) {
>> + gid = pw->pw_gid;
>> + uid = pw->pw_uid;
>> + } else {
>> + gid = 65534;
>> + uid = 65534;
>> + }
>> +
>> + SAFE_SETREGID(gid, gid);
>> + SAFE_SETREUID(uid, uid);
>> +}
>> +
>> +static void setup(void)
>> +{
>> + tst_taint_init(TST_TAINT_W | TST_TAINT_D | TST_TAINT_L);
>> +
>> + if (!dir)
>> + tst_brk(TBROK, "No reproducer directory specified");
>> +
>> + if (!name)
>> + tst_brk(TBROK, "No reproducer name specified");
>> +
>> + tst_res(TINFO, "https://syzkaller.appspot.com/bug?id=%s", name);
>> +
>> + SAFE_ASPRINTF(&path, "%s/%s", dir, name);
>> + tst_res(TINFO, "%s", path);
>> +}
>> +
>> +static void run(void)
>> +{
>> + unsigned int backoff = 100;
>> + int rem, status, sent_kill = 0;
>> + float exec_time_start = (float)tst_timeout_remaining();
>> + int pid;
>> +
>> + if (sandbox)
>> + SAFE_UNSHARE(CLONE_NEWPID);
>> +
>> + pid = SAFE_FORK();
>> + if (!pid) {
>> + if (sandbox) {
>> + SAFE_UNSHARE(CLONE_NEWNET);
>> + become_nobody();
>> + }
>> +
>> + if (prctl(PR_SET_DUMPABLE, 1, 0, 0, 0)) {
>> + tst_res(TWARN | TERRNO,
>> + "Failed to set dumpable; won't be able to open /proc/self/*");
>> + }
>> +
>> + execl(path, name, NULL);
>> + tst_brk(TBROK | TERRNO, "Failed to exec reproducer");
>> + }
>> +
>> + while (!waitpid(pid, &status, WNOHANG)) {
>> + rem = tst_timeout_remaining();
>> +
>> + if (!sent_kill && rem / exec_time_start < 0.5) {
>> + tst_res(TINFO, "Timeout; killing reproducer");
>> +
>> + TEST(kill(pid, SIGKILL));
>> + if (TST_RET == -1)
>> + tst_res(TWARN | TTERRNO, "kill() failed");
>> + else
>> + sent_kill = 1;
>> + }
>> +
>> + usleep(backoff);
>> + backoff = MIN(2 * backoff, 1000000);
>> + }
>> +
>> + if (tst_taint_check()) {
>> + tst_res(TFAIL, "Kernel is tainted");
>> + } else {
>> + tst_res(TPASS, "Kernel is not tainted");
>> + }
>> +}
>> +
>> +static struct tst_test test = {
>> + .setup = setup,
>> + .test_all = run,
>> + .options = options,
>> + .needs_tmpdir = 1,
>> + .forks_child = 1,
>> + .timeout = 20
>> +};
>> diff --git a/testcases/linux-arts b/testcases/linux-arts
>> new file mode 160000
>> index 000000000..07759b820
>> --- /dev/null
>> +++ b/testcases/linux-arts
>> @@ -0,0 +1 @@
>> +Subproject commit 07759b820a9cbf01333d861d8eb2613b20d1ede4
>> --
>> 2.23.0
>>
>> --
>> You received this message because you are subscribed to the Google Groups "syzkaller" group.
>> To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller+unsubscribe@googlegroups.com.
>> To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller/20191204103120.29440-1-rpalethorpe%40suse.com.
--
Thank you,
Richard.
More information about the ltp
mailing list