From 4b9efdc986616b6b7b70d7c188b267f95237931e Mon Sep 17 00:00:00 2001
From: bulaza <bulaza@users.noreply.github.com>
Date: Sat, 13 May 2017 13:16:17 -0400
Subject: [PATCH] Adding INSN hook checks for x86 (#833)

* adding INSN hook checking for x86

* tabs to spaces

* need to return bool not uc_err

* fixed conditional after switching to bool
---
 include/uc_priv.h          |  5 +++++
 qemu/target-i386/unicorn.c | 14 +++++++++++++-
 uc.c                       |  7 +++++++
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/include/uc_priv.h b/include/uc_priv.h
index 9b15bbfe..5c47fb91 100644
--- a/include/uc_priv.h
+++ b/include/uc_priv.h
@@ -78,6 +78,9 @@ typedef bool (*uc_args_int_t)(int intno);
 // some architecture redirect virtual memory to physical memory like Mips
 typedef uint64_t (*uc_mem_redirect_t)(uint64_t address);
 
+// validate if Unicorn supports hooking a given instruction
+typedef bool(*uc_insn_hook_validate)(uint32_t insn_enum);
+
 struct hook {
     int type;            // UC_HOOK_*
     int insn;            // instruction for HOOK_INSN
@@ -169,6 +172,8 @@ struct uc_struct {
     // TODO: remove current_cpu, as it's a flag for something else ("cpu running"?)
     CPUState *cpu, *current_cpu;
 
+    uc_insn_hook_validate insn_hook_validate;
+
     MemoryRegion *system_memory;    // qemu/exec.c
     MemoryRegion io_mem_rom;    // qemu/exec.c
     MemoryRegion io_mem_notdirty;   // qemu/exec.c
diff --git a/qemu/target-i386/unicorn.c b/qemu/target-i386/unicorn.c
index 08ea9a11..8fc8c410 100644
--- a/qemu/target-i386/unicorn.c
+++ b/qemu/target-i386/unicorn.c
@@ -171,7 +171,7 @@ static int x86_msr_read(struct uc_struct *uc, uc_x86_msr *msr)
     helper_rdmsr(env);
 
     msr->value = ((uint32_t)env->regs[R_EAX]) |
-    	((uint64_t)((uint32_t)env->regs[R_EDX]) << 32);
+        ((uint64_t)((uint32_t)env->regs[R_EDX]) << 32);
 
     env->regs[R_EAX] = eax;
     env->regs[R_ECX] = ecx;
@@ -1335,6 +1335,17 @@ static bool x86_stop_interrupt(int intno)
 
 void pc_machine_init(struct uc_struct *uc);
 
+static bool x86_insn_hook_validate(uint32_t insn_enum)
+{
+    //for x86 we can only hook IN, OUT, and SYSCALL
+    if (insn_enum != UC_X86_INS_IN
+        &&  insn_enum != UC_X86_INS_OUT
+        &&  insn_enum != UC_X86_INS_SYSCALL) {
+        return false;
+    }
+    return true;
+}
+
 DEFAULT_VISIBILITY
 void x86_uc_init(struct uc_struct* uc)
 {
@@ -1350,6 +1361,7 @@ void x86_uc_init(struct uc_struct* uc)
     uc->release = x86_release;
     uc->set_pc = x86_set_pc;
     uc->stop_interrupt = x86_stop_interrupt;
+    uc->insn_hook_validate = x86_insn_hook_validate;
     uc_common_init(uc);
 }
 
diff --git a/uc.c b/uc.c
index 370f7b95..192b67d0 100644
--- a/uc.c
+++ b/uc.c
@@ -1036,6 +1036,13 @@ uc_err uc_hook_add(uc_engine *uc, uc_hook *hh, int type, void *callback,
         hook->insn = va_arg(valist, int);
         va_end(valist);
 
+        if (uc->insn_hook_validate) {
+            if (! uc->insn_hook_validate(hook->insn)) {
+                free(hook);
+                return UC_ERR_HOOK;
+            }
+        }
+
         if (list_append(&uc->hook[UC_HOOK_INSN_IDX], hook) == NULL) {
             free(hook);
             return UC_ERR_NOMEM;