Run thread hooks for KVM mode (#84)

* Run thread hooks for KVM mode

* Unify qemu init function symbol for systemmode and usermode

* get tid from caller instead of callee

Author: rmalmain

accel/kvm/kvm-accel-ops.c

@@ -26,6 +26,12 @@
 #include <linux/kvm.h>
 #include "kvm-cpus.h"
 
+//// --- Begin LibAFL code ---
+
+#include "libafl/hooks/thread.h"
+
+//// --- End LibAFL code ---
+
 static void *kvm_vcpu_thread_fn(void *arg)
 {
     CPUState *cpu = arg;
@@ -41,6 +47,12 @@ static void *kvm_vcpu_thread_fn(void *arg)
     r = kvm_init_vcpu(cpu, &error_fatal);
     kvm_init_cpu_signals(cpu);
 
+//// --- Begin LibAFL code ---
+
+    libafl_hook_new_thread_run(cpu_env(cpu), cpu->thread_id);
+
+//// --- End LibAFL code ---
+
     /* signal CPU creation */
     cpu_thread_signal_created(cpu);
     qemu_guest_random_seed_thread_part2(cpu->random_seed);

include/libafl/hooks/thread.h

@@ -28,4 +28,4 @@ size_t libafl_add_new_thread_hook(bool (*callback)(uint64_t data,
                                   uint64_t data);
 int libafl_qemu_remove_new_thread_hook(size_t num);
 
-bool libafl_hook_new_thread_run(CPUArchState* env);
+bool libafl_hook_new_thread_run(CPUArchState* env, uint32_t tid);

include/libafl/system.h

@@ -0,0 +1,3 @@
+#pragma once
+
+void libafl_qemu_init(int argc, char** argv);

include/libafl/user.h

@@ -30,3 +30,9 @@ struct image_info* libafl_get_image_info(void);
 
 uint64_t libafl_get_brk(void);
 uint64_t libafl_set_brk(uint64_t new_brk);
+
+int _libafl_qemu_user_init(int argc, char** argv, char** envp);
+
+#ifdef AS_LIB
+void libafl_qemu_init(int argc, char** argv);
+#endif

libafl/hooks/thread.c

@@ -24,13 +24,14 @@ size_t libafl_add_new_thread_hook(bool (*callback)(uint64_t data,
     return hook->num;
 }
 
-bool libafl_hook_new_thread_run(CPUArchState* env)
+bool libafl_hook_new_thread_run(CPUArchState* env, uint32_t tid)
 {
+#ifdef CONFIG_USER_ONLY
     libafl_set_qemu_env(env);
+#endif
 
     if (libafl_new_thread_hooks) {
         bool continue_execution = true;
-        int tid = gettid();
 
         struct libafl_new_thread_hook* h = libafl_new_thread_hooks;
         while (h) {

libafl/meson.build

@@ -16,9 +16,11 @@ specific_ss.add(files(
 
                     # General hooks
                     'hooks/cpu_run.c',
+                    'hooks/thread.c',
                 ))
 
 specific_ss.add(when : 'CONFIG_SOFTMMU', if_true : [files(
+                                                        'system.c',
                                                         'qemu_snapshot.c',
                                                         'syx-snapshot/device-save.c',
                                                         'syx-snapshot/syx-snapshot.c',
@@ -29,6 +31,5 @@ specific_ss.add(when : 'CONFIG_SOFTMMU', if_true : [files(
 specific_ss.add(when : 'CONFIG_USER_ONLY', if_true : [files(
                                                           'user.c',
                                                           'hooks/syscall.c',
-                                                          'hooks/thread.c',
                                                     )])
 

libafl/system.c

@@ -0,0 +1,6 @@
+#include "qemu/osdep.h"
+#include "sysemu/sysemu.h"
+
+#include "libafl/system.h"
+
+void libafl_qemu_init(int argc, char** argv) { qemu_init(argc, argv); }

libafl/user.c

@@ -35,3 +35,11 @@ uint64_t libafl_set_brk(uint64_t new_brk)
     target_brk = (abi_ulong)new_brk;
     return old_brk;
 }
+
+#ifdef AS_LIB
+void libafl_qemu_init(int argc, char** argv)
+{
+    // main function in usermode has an env parameter but is unused in practice.
+    _libafl_qemu_user_init(argc, argv, NULL);
+}
+#endif

linux-user/main.c

@@ -693,8 +693,7 @@ static int parse_args(int argc, char **argv)
 struct linux_binprm bprm;
 
 #ifdef AS_LIB
-int qemu_user_init(int argc, char **argv, char **envp);
-int qemu_user_init(int argc, char **argv, char **envp)
+int _libafl_qemu_user_init(int argc, char **argv, char **envp)
 #else
 //// --- End LibAFL code ---
 int main(int argc, char **argv, char **envp)

linux-user/syscall.c

@@ -6556,7 +6556,7 @@ static void *clone_func(void *arg)
 
     //// --- Begin LibAFL code ---
 
-    if (libafl_hook_new_thread_run(env)) {
+    if (libafl_hook_new_thread_run(env, info->tid)) {
         cpu_loop(env);
     }