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[PATCH v4 15/20] fuzz: add fuzzer skeleton
From: |
Oleinik, Alexander |
Subject: |
[PATCH v4 15/20] fuzz: add fuzzer skeleton |
Date: |
Wed, 30 Oct 2019 14:50:00 +0000 |
From: Alexander Oleinik <address@hidden>
tests/fuzz/fuzz.c serves as the entry point for the virtual-device
fuzzer. Namely, libfuzzer invokes the LLVMFuzzerInitialize and
LLVMFuzzerTestOneInput functions, both of which are defined in this
file. This change adds a "FuzzTarget" struct, along with the
fuzz_add_target function, which should be used to define new fuzz
targets.
Signed-off-by: Alexander Oleinik <address@hidden>
---
tests/fuzz/Makefile.include | 4 +-
tests/fuzz/fuzz.c | 177 ++++++++++++++++++++++++++++++++++++
tests/fuzz/fuzz.h | 66 ++++++++++++++
3 files changed, 245 insertions(+), 2 deletions(-)
create mode 100644 tests/fuzz/fuzz.c
create mode 100644 tests/fuzz/fuzz.h
diff --git a/tests/fuzz/Makefile.include b/tests/fuzz/Makefile.include
index 324e6c1433..b415b056b0 100644
--- a/tests/fuzz/Makefile.include
+++ b/tests/fuzz/Makefile.include
@@ -1,4 +1,4 @@
-# QEMU_PROG_FUZZ=qemu-fuzz-$(TARGET_NAME)$(EXESUF)
+QEMU_PROG_FUZZ=qemu-fuzz-$(TARGET_NAME)$(EXESUF)
fuzz-obj-y = $(libqos-obj-y)
fuzz-obj-y += tests/libqtest.o
-
+fuzz-obj-y += tests/fuzz/fuzz.o
diff --git a/tests/fuzz/fuzz.c b/tests/fuzz/fuzz.c
new file mode 100644
index 0000000000..0e38f81c48
--- /dev/null
+++ b/tests/fuzz/fuzz.c
@@ -0,0 +1,177 @@
+/*
+ * fuzzing driver
+ *
+ * Copyright Red Hat Inc., 2019
+ *
+ * Authors:
+ * Alexander Bulekov <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu/osdep.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <wordexp.h>
+
+
+#include "tests/libqtest.h"
+#include "sysemu/qtest.h"
+#include "fuzz.h"
+#include "tests/libqos/qgraph.h"
+#include "sysemu/runstate.h"
+#include "sysemu/sysemu.h"
+#include "qemu/main-loop.h"
+
+typedef struct FuzzTargetState {
+ FuzzTarget *target;
+ QSLIST_ENTRY(FuzzTargetState) target_list;
+} FuzzTargetState;
+
+typedef QSLIST_HEAD(, FuzzTargetState) FuzzTargetList;
+
+static const char *fuzz_arch = TARGET_NAME;
+
+static FuzzTargetList *fuzz_target_list;
+static FuzzTarget *fuzz_target;
+static QTestState *fuzz_qts;
+
+
+
+void flush_events(QTestState *s)
+{
+ int i = 10;
+ while (g_main_context_pending(NULL) && i-- > 0) {
+ main_loop_wait(false);
+ }
+}
+
+static QTestState *qtest_setup(void)
+{
+ qtest_server_set_tx_handler(&qtest_client_inproc_recv, NULL);
+ return qtest_inproc_init(false, fuzz_arch, &qtest_server_inproc_recv);
+}
+
+void fuzz_add_target(FuzzTarget *target)
+{
+ FuzzTargetState *tmp;
+ FuzzTargetState *target_state;
+ if (!fuzz_target_list) {
+ fuzz_target_list = g_new0(FuzzTargetList, 1);
+ }
+
+ QSLIST_FOREACH(tmp, fuzz_target_list, target_list) {
+ if (g_strcmp0(tmp->target->name, target->name) == 0) {
+ fprintf(stderr, "Error: Fuzz target name %s already in use\n",
+ target->name);
+ abort();
+ }
+ }
+ target_state = g_new0(FuzzTargetState, 1);
+ target_state->target = g_new0(FuzzTarget, 1);
+ *(target_state->target) = *target;
+ QSLIST_INSERT_HEAD(fuzz_target_list, target_state, target_list);
+}
+
+
+
+static void usage(char *path)
+{
+ printf("Usage: %s --fuzz-target=FUZZ_TARGET [LIBFUZZER ARGUMENTS]\n",
path);
+ printf("where FUZZ_TARGET is one of:\n");
+ FuzzTargetState *tmp;
+ if (!fuzz_target_list) {
+ fprintf(stderr, "Fuzz target list not initialized\n");
+ abort();
+ }
+ QSLIST_FOREACH(tmp, fuzz_target_list, target_list) {
+ printf(" %s : %s\n", tmp->target->name,
+ tmp->target->description);
+ }
+ exit(0);
+}
+
+static FuzzTarget *fuzz_get_target(char* name)
+{
+ FuzzTargetState *tmp;
+ if (!fuzz_target_list) {
+ fprintf(stderr, "Fuzz target list not initialized\n");
+ abort();
+ }
+
+ QSLIST_FOREACH(tmp, fuzz_target_list, target_list) {
+ if (strcmp(tmp->target->name, name) == 0) {
+ return tmp->target;
+ }
+ }
+ return NULL;
+}
+
+
+/* Executed for each fuzzing-input */
+int LLVMFuzzerTestOneInput(const unsigned char *Data, size_t Size)
+{
+ if (fuzz_target->fuzz) {
+ fuzz_target->fuzz(fuzz_qts, Data, Size);
+ }
+ return 0;
+}
+
+/* Executed once, prior to fuzzing */
+int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp)
+{
+
+ char *target_name;
+
+ /* Initialize qgraph and modules */
+ qos_graph_init();
+ module_call_init(MODULE_INIT_FUZZ_TARGET);
+ module_call_init(MODULE_INIT_QOM);
+ module_call_init(MODULE_INIT_LIBQOS);
+
+ if (*argc <= 1) {
+ usage(**argv);
+ }
+
+ /* Identify the fuzz target */
+ target_name = (*argv)[1];
+ if (!strstr(target_name, "--fuzz-target=")) {
+ usage(**argv);
+ }
+
+ target_name += strlen("--fuzz-target=");
+
+ fuzz_target = fuzz_get_target(target_name);
+ if (!fuzz_target) {
+ usage(**argv);
+ }
+
+ fuzz_qts = qtest_setup();
+
+ if (!fuzz_target) {
+ fprintf(stderr, "Error: Fuzz fuzz_target name %s not found\n",
+ target_name);
+ usage(**argv);
+ }
+
+ if (fuzz_target->pre_vm_init) {
+ fuzz_target->pre_vm_init();
+ }
+
+ /* Run QEMU's softmmu main with the fuzz-target dependent arguments */
+ char *init_cmdline = fuzz_target->get_init_cmdline(fuzz_target);
+
+ wordexp_t result;
+ wordexp(init_cmdline, &result, 0);
+
+ qemu_init(result.we_wordc, result.we_wordv, NULL);
+
+ if (fuzz_target->pre_fuzz) {
+ fuzz_target->pre_fuzz(fuzz_qts);
+ }
+
+ return 0;
+}
diff --git a/tests/fuzz/fuzz.h b/tests/fuzz/fuzz.h
new file mode 100644
index 0000000000..b569b622d7
--- /dev/null
+++ b/tests/fuzz/fuzz.h
@@ -0,0 +1,66 @@
+/*
+ * fuzzing driver
+ *
+ * Copyright Red Hat Inc., 2019
+ *
+ * Authors:
+ * Alexander Bulekov <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef FUZZER_H_
+#define FUZZER_H_
+
+#include "qemu/osdep.h"
+#include "qemu/units.h"
+#include "qapi/error.h"
+#include "exec/memory.h"
+#include "tests/libqtest.h"
+
+
+typedef struct FuzzTarget {
+ const char *name; /* command-line option(FUZZ_TARGET) for the
target */
+ const char *description; /* help text */
+
+
+ /* returns the arg-list that is passed to qemu/softmmu init() */
+ char* (*get_init_cmdline)(struct FuzzTarget *);
+
+ /*
+ * will run once, prior to running qemu/softmmu init.
+ * eg: set up shared-memory for communication with the child-process
+ */
+ void(*pre_vm_init)(void);
+
+ /*
+ * will run once, prior to to the fuzz-loop.
+ * eg: detect the memory map
+ */
+ void(*pre_fuzz)(QTestState *);
+
+ /*
+ * accepts and executes an input from libfuzzer. this is repeatedly
+ * executed during the fuzzing loop. Its should handle setup, input
+ * execution and cleanup
+ */
+ void(*fuzz)(QTestState *, const unsigned char *, size_t);
+
+} FuzzTarget;
+
+void flush_events(QTestState *);
+void reboot(QTestState *);
+
+/*
+ * makes a copy of *target and adds it to the target-list.
+ * i.e. fine to set up target on the caller's stack
+ */
+void fuzz_add_target(FuzzTarget *target);
+
+int LLVMFuzzerTestOneInput(const unsigned char *Data, size_t Size);
+int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp);
+
+#endif
+
--
2.23.0
- [PATCH v4 11/20] libqtest: make qtest_bufwrite send "atomic", (continued)
- [PATCH v4 11/20] libqtest: make qtest_bufwrite send "atomic", Oleinik, Alexander, 2019/10/30
- [PATCH v4 09/20] libqos: split qos-test and libqos makefile vars, Oleinik, Alexander, 2019/10/30
- [PATCH v4 06/20] module: check module wasn't already initialized, Oleinik, Alexander, 2019/10/30
- [PATCH v4 05/20] libqtest: Add a layer of abstraciton to send/recv, Oleinik, Alexander, 2019/10/30
- [PATCH v4 07/20] qtest: add in-process incoming command handler, Oleinik, Alexander, 2019/10/30
- [PATCH v4 02/20] libqos: Rename i2c_send and i2c_recv, Oleinik, Alexander, 2019/10/30
- [PATCH v4 08/20] tests: provide test variables to other targets, Oleinik, Alexander, 2019/10/30
- [PATCH v4 13/20] fuzz: add configure flag --enable-fuzzing, Oleinik, Alexander, 2019/10/30
- [PATCH v4 12/20] libqtest: add in-process qtest.c tx/rx handlers, Oleinik, Alexander, 2019/10/30
- [PATCH v4 10/20] libqos: move useful qos-test funcs to qos_external, Oleinik, Alexander, 2019/10/30
- [PATCH v4 15/20] fuzz: add fuzzer skeleton,
Oleinik, Alexander <=
- [PATCH v4 16/20] fuzz: add support for fork-based fuzzing., Oleinik, Alexander, 2019/10/30
- [PATCH v4 14/20] fuzz: Add target/fuzz makefile rules, Oleinik, Alexander, 2019/10/30
- [PATCH v4 18/20] fuzz: add i440fx fuzz targets, Oleinik, Alexander, 2019/10/30
- [PATCH v4 17/20] fuzz: add support for qos-assisted fuzz targets, Oleinik, Alexander, 2019/10/30
- [PATCH v4 20/20] fuzz: add documentation to docs/devel/, Oleinik, Alexander, 2019/10/30
- [PATCH v4 19/20] fuzz: add virtio-net fuzz target, Oleinik, Alexander, 2019/10/30
- Re: [PATCH v4 00/20] Add virtual device fuzzing support, no-reply, 2019/10/30