[Qemu-devel] [RFC PATCH v2 12/17] fuzz: Add fuzzer skeleton

["Oleinik, Alexander" <alxndr@bu.edu>]

The code defines the lifecycle of the fuzzer, and provides rebooting,
vmload and device_load as means of resetting state between fuzz runs

Signed-off-by: Alexander Oleinik <alxndr@bu.edu>
---
 tests/fuzz/fuzz.c | 245 ++++++++++++++++++++++++++++++++++++++++++++++
 tests/fuzz/fuzz.h |  70 +++++++++++++
 2 files changed, 315 insertions(+)
 create mode 100644 tests/fuzz/fuzz.c
 create mode 100644 tests/fuzz/fuzz.h

diff --git a/tests/fuzz/fuzz.c b/tests/fuzz/fuzz.c
new file mode 100644
index 0000000000..9e03e15d7b
--- /dev/null
+++ b/tests/fuzz/fuzz.c
@@ -0,0 +1,245 @@
+#include "qemu/osdep.h"
+#include "qemu-common.h"
+#include "qemu/iov.h"
+#include "exec/memory.h"
+#include "exec/address-spaces.h"
+#include "migration/qemu-file.h"
+
+#include "migration/qemu-file.h"
+#include "migration/global_state.h"
+#include "migration/savevm.h"
+#include "tests/libqtest.h"
+#include "migration/migration.h"
+#include "fuzz.h"
+#include "tests/libqos/qgraph.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <linux/userfaultfd.h>
+#include <poll.h>
+#include <pthread.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <sys/ioctl.h>
+
+QTestState *s;
+
+QEMUFile *ramfile;
+QEMUFile *writefile;
+ram_disk *rd;
+
+
+typedef struct FuzzTargetState {
+        FuzzTarget *target;
+        QSLIST_ENTRY(FuzzTargetState) target_list;
+} FuzzTargetState;
+
+typedef QSLIST_HEAD(, FuzzTargetState) FuzzTargetList;
+
+FuzzTargetList *fuzz_target_list;
+
+/* Save just the VMStateDescriptors */
+void save_device_state(void)
+{
+    writefile = qemu_fopen_ram(&rd);
+    global_state_store();
+    qemu_save_device_state(writefile);
+    qemu_fflush(writefile);
+    ramfile = qemu_fopen_ro_ram(rd);
+}
+
+/* Save the entire vm state including RAM */
+void save_vm_state(void)
+{
+    writefile = qemu_fopen_ram(&rd);
+    vm_stop(RUN_STATE_SAVE_VM);
+    global_state_store();
+    qemu_savevm_state(writefile, NULL);
+    qemu_fflush(writefile);
+    ramfile = qemu_fopen_ro_ram(rd);
+}
+
+/* Reset state by rebooting */
+void reboot()
+{
+    qemu_system_reset(SHUTDOWN_CAUSE_NONE);
+}
+
+/* Restore device state */
+void load_device_state()
+{
+    qemu_freopen_ro_ram(ramfile);
+
+    int ret = qemu_load_device_state(ramfile);
+    if (ret < 0) {
+        printf("reset error\n");
+        exit(-1);
+    }
+}
+
+/* Restore full vm state */
+void load_vm_state()
+{
+    qemu_freopen_ro_ram(ramfile);
+
+    vm_stop(RUN_STATE_RESTORE_VM);
+
+    int ret = qemu_loadvm_state(ramfile);
+    if (ret < 0) {
+        printf("reset error\n");
+        exit(-1);
+    }
+    migration_incoming_state_destroy();
+    vm_start();
+}
+
+void qtest_setup()
+{
+    s = qtest_fuzz_init(NULL, NULL);
+    global_qtest = s;
+}
+
+void fuzz_add_target(const char *name, const char *description,
+        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->str, name) == 0) {
+            fprintf(stderr, "Error: Fuzz target name %s already in use\n",
+                    name);
+            abort();
+        }
+    }
+    target_state = g_new0(FuzzTargetState, 1);
+    target_state->target = g_new0(FuzzTarget, 1);
+    *(target_state->target) = *target;
+    target_state->target->name = g_string_new(name);
+    target_state->target->description = g_string_new(description);
+    QSLIST_INSERT_HEAD(fuzz_target_list, target_state, target_list);
+}
+
+
+static FuzzTarget *fuzz_get_target(char* name)
+{
+    FuzzTargetState *tmp;
+    if (!fuzz_target_list) {
+        fprintf(stderr, "Fuzz target list not initialized");
+        abort();
+    }
+
+    QSLIST_FOREACH(tmp, fuzz_target_list, target_list) {
+        if (g_strcmp0(tmp->target->name->str, name) == 0) {
+            break;
+        }
+    }
+    return tmp->target;
+}
+
+FuzzTarget *fuzz_target;
+
+
+
+static void usage(void)
+{
+    printf("Usage: ./fuzz --FUZZ_TARGET [LIBFUZZER ARGUMENTS]\n");
+    printf("where --FUZZ_TARGET is one of:\n");
+    FuzzTargetState *tmp;
+    if (!fuzz_target_list) {
+        fprintf(stderr, "Fuzz target list not initialized");
+        abort();
+    }
+    QSLIST_FOREACH(tmp, fuzz_target_list, target_list) {
+        printf(" --%s  : %s\n", tmp->target->name->str,
+                tmp->target->description->str);
+    }
+    exit(0);
+}
+
+static void enum_memory(void)
+{
+    /* TODO: Enumerate interesting memory using memory_region_is_ram */
+    return;
+}
+
+/* Executed for each fuzzing-input */
+int LLVMFuzzerTestOneInput(const unsigned char *Data, size_t Size)
+{
+    /* e.g. Device bootstrapping */
+    if (fuzz_target->pre_fuzz) {
+        fuzz_target->pre_fuzz();
+    }
+
+    if (fuzz_target->fuzz) {
+        fuzz_target->fuzz(Data, Size);
+    }
+
+    /* e.g. Copy counter bitmap to shm*/
+    if (fuzz_target->post_fuzz) {
+        fuzz_target->post_fuzz();
+    }
+
+    /* e.g. Reboot the machine or vmload */
+    if (fuzz_target->reset) {
+        fuzz_target->reset();
+    }
+
+    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();
+    }
+
+
+    /* Identify the fuzz target */
+    target_name = (*argv)[1];
+    target_name += 2;
+    fuzz_target = fuzz_get_target(target_name);
+
+    if (!fuzz_target) {
+        fprintf(stderr, "Error: Fuzz fuzz_target name %s not found\n",
+                target_name);
+        usage();
+    }
+
+    if (fuzz_target->pre_main) {
+        fuzz_target->pre_main();
+    }
+
+    /* Run QEMU's regular vl.c:main */
+    qemu_init(*(fuzz_target->main_argc), *(fuzz_target->main_argv), NULL);
+
+
+    /* Enumerate memory to identify mapped MMIO and I/O regions */
+    enum_memory();
+
+    /* Good place to do any one-time device initialization (such as QOS init) */
+    if (fuzz_target->pre_save_state) {
+        fuzz_target->pre_save_state();
+    }
+
+    /* If configured, this is where we save vm or device state to ramdisk */
+    if (fuzz_target->save_state) {
+        fuzz_target->save_state();
+    }
+
+    return 0;
+}
diff --git a/tests/fuzz/fuzz.h b/tests/fuzz/fuzz.h
new file mode 100644
index 0000000000..46ec38d4ea
--- /dev/null
+++ b/tests/fuzz/fuzz.h
@@ -0,0 +1,70 @@
+#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"
+#include "migration/qemu-file.h"
+
+#include <linux/userfaultfd.h>
+
+
+extern QTestState *s;
+extern QEMUFile *writefile;
+extern QEMUFile *ramfile;
+extern ram_disk *rd;
+
+typedef struct FuzzTarget {
+    GString *name;
+    GString *description;
+    void(*pre_main)(void);
+    void(*pre_save_state)(void);
+    void(*save_state)(void);
+    void(*reset)(void);
+    void(*pre_fuzz)(void);
+    void(*fuzz)(const unsigned char*, size_t);
+    void(*post_fuzz)(void);
+    int *main_argc;
+    char ***main_argv;
+} FuzzTarget;
+
+
+void save_device_state(void);
+void save_vm_state(void);
+void reboot(void);
+
+void load_device_state(void);
+void load_vm_state(void);
+
+
+void save_device_state(void);
+void qtest_setup(void);
+void fuzz_register_mr(const MemoryRegion *mr);
+
+extern FuzzTarget *fuzz_target;
+
+typedef struct fuzz_memory_region {
+    bool io;
+    uint64_t start;
+    uint64_t length;
+    struct fuzz_memory_region *next;
+} fuzz_memory_region;
+
+extern fuzz_memory_region *fuzz_memory_region_head;
+extern fuzz_memory_region *fuzz_memory_region_tail;
+
+extern uint64_t total_io_mem;
+extern uint64_t total_ram_mem;
+
+
+
+void fuzz_add_target(const char *name, const char *description, FuzzTarget
+        *target);
+
+int LLVMFuzzerTestOneInput(const unsigned char *Data, size_t Size);
+int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp);
+
+#endif
+
-- 
2.20.1