[Automated-testing] [PATCH 1/2] Wrapper for Syzkaller reproducers
Dmitry Vyukov
dvyukov at google.com
Thu Nov 7 07:43:31 PST 2019
On Thu, Nov 7, 2019 at 4:35 PM Richard Palethorpe <rpalethorpe at suse.com> wrote:
>
> Allows one to run the Syzkaller reproducers as part of the LTP.
>
> Signed-off-by: Richard Palethorpe <rpalethorpe at suse.com>
> ---
> .gitmodules | 5 +
> configure.ac | 11 ++
> include/mk/features.mk.default | 2 +
> include/mk/features.mk.in | 2 +
> runtest/.gitignore | 1 +
> testcases/kernel/Makefile | 1 +
> testcases/kernel/syzkaller-repros/.gitignore | 1 +
> testcases/kernel/syzkaller-repros/Makefile | 100 ++++++++++++++
> testcases/kernel/syzkaller-repros/README.md | 45 +++++++
> testcases/kernel/syzkaller-repros/syzwrap.c | 133 +++++++++++++++++++
> 10 files changed, 301 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
>
> diff --git a/.gitmodules b/.gitmodules
> index 1c9e9c38a..6a2d31f51 100644
> --- a/.gitmodules
> +++ b/.gitmodules
> @@ -1,3 +1,8 @@
> [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
> + ignore = all
> diff --git a/configure.ac b/configure.ac
> index 3785dff63..ec4cae483 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -184,6 +184,17 @@ 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=$withval]
> +)
> +if test "x$with_syzkaller_repros" = xyes; then
> + AC_SUBST([WITH_SYZKALLER_REPROS],["yes"])
> +else
> + AC_SUBST([WITH_SYZKALLER_REPROS],["no"])
> +fi
> +
> # testcases/realtime requires bash and python.
> if test "x$with_bash" = xyes && test "x$with_python" = xyes; then
> AC_ARG_WITH([realtime-testsuite],
> diff --git a/include/mk/features.mk.default b/include/mk/features.mk.default
> index 3a6cc5176..71fb48c60 100644
> --- a/include/mk/features.mk.default
> +++ b/include/mk/features.mk.default
> @@ -47,3 +47,5 @@ WITH_REALTIME_TESTSUITE := no
> else
> WITH_REALTIME_TESTSUITE := no
> endif
> +
> +WITH_SYZKALLER_REPROS := no
> 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..d40d61ac1
> --- /dev/null
> +++ b/testcases/kernel/syzkaller-repros/Makefile
> @@ -0,0 +1,100 @@
> +# 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)
> +
> +# 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
> + - at 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..9f5d16078
> --- /dev/null
> +++ b/testcases/kernel/syzkaller-repros/syzwrap.c
> @@ -0,0 +1,133 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2019 Richard Palethorpe <rpalethorpe at 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
> +};
> --
> 2.23.0
>
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