pe: add dll characteristic linker options

Add PE linker switches to set and clear DYNAMIC_BASE, NX_COMPAT,
HIGH_ENTROPY_VA and TERMINAL_SERVER_AWARE without changing x86/x64
defaults. HIGH_ENTROPY_VA is limited to 64-bit PE targets and implies
DYNAMIC_BASE; clearing DYNAMIC_BASE also clears HIGH_ENTROPY_VA.

When DYNAMIC_BASE is requested for an executable, emit base relocations
and clear RELOCS_STRIPPED so Windows ASLR can relocate the image. Keep
the existing ARM64 default hardening flags.

libtcc.c

@@ -1406,6 +1406,20 @@ succ:
 
 static void args_parser_add_file(TCCState *s, const char* filename, int filetype);
 
+#ifdef TCC_TARGET_PE
+static void tcc_pe_set_dll_characteristics(TCCState *s, unsigned flags)
+{
+    s->pe_dll_characteristics |= flags;
+    s->pe_dll_characteristics_clear &= ~flags;
+}
+
+static void tcc_pe_clear_dll_characteristics(TCCState *s, unsigned flags)
+{
+    s->pe_dll_characteristics &= ~flags;
+    s->pe_dll_characteristics_clear |= flags;
+}
+#endif
+
 /* set linker options */
 static int tcc_set_linker(TCCState *s, const char *optarg)
 {
@@ -1475,7 +1489,31 @@ static int tcc_set_linker(TCCState *s, const char *optarg)
             s->znodelete = 1;
 #ifdef TCC_TARGET_PE
         } else if (link_option(&o, "large-address-aware")) {
-            s->pe_characteristics |= 0x20;
+            s->pe_characteristics |= PE_IMAGE_FILE_LARGE_ADDRESS_AWARE;
+        } else if (link_option(&o, "dynamicbase")) {
+            tcc_pe_set_dll_characteristics(s, PE_DLLCHARACTERISTICS_DYNAMIC_BASE);
+        } else if (link_option(&o, "disable-dynamicbase|no-dynamicbase")) {
+            tcc_pe_clear_dll_characteristics(s,
+                PE_DLLCHARACTERISTICS_DYNAMIC_BASE |
+                PE_DLLCHARACTERISTICS_HIGH_ENTROPY_VA);
+        } else if (link_option(&o, "nxcompat")) {
+            tcc_pe_set_dll_characteristics(s, PE_DLLCHARACTERISTICS_NX_COMPAT);
+        } else if (link_option(&o, "disable-nxcompat|no-nxcompat")) {
+            tcc_pe_clear_dll_characteristics(s, PE_DLLCHARACTERISTICS_NX_COMPAT);
+        } else if (link_option(&o, "high-entropy-va")) {
+# if defined(TCC_TARGET_X86_64) || defined(TCC_TARGET_ARM64)
+            tcc_pe_set_dll_characteristics(s,
+                PE_DLLCHARACTERISTICS_HIGH_ENTROPY_VA |
+                PE_DLLCHARACTERISTICS_DYNAMIC_BASE);
+# else
+            goto err;
+# endif
+        } else if (link_option(&o, "disable-high-entropy-va|no-high-entropy-va")) {
+            tcc_pe_clear_dll_characteristics(s, PE_DLLCHARACTERISTICS_HIGH_ENTROPY_VA);
+        } else if (link_option(&o, "tsaware")) {
+            tcc_pe_set_dll_characteristics(s, PE_DLLCHARACTERISTICS_TERMINAL_SERVER_AWARE);
+        } else if (link_option(&o, "disable-tsaware|no-tsaware")) {
+            tcc_pe_clear_dll_characteristics(s, PE_DLLCHARACTERISTICS_TERMINAL_SERVER_AWARE);
         } else if (link_option(&o, "file-alignment=")) {
             s->pe_file_align = strtoul(o.arg, &end, 16);
         } else if (link_option(&o, "stack=")) {

tcc-doc.texi

@@ -386,6 +386,15 @@ Set type for PE (Windows) executables.
 @item -Wl,-[Ttext=# | section-alignment=# | file-alignment=# | image-base=# | stack=#]
 Modify executable layout.
 
+@item -Wl,-[dynamicbase | nxcompat | high-entropy-va | tsaware]
+@item -Wl,-[no-dynamicbase | no-nxcompat | no-high-entropy-va | no-tsaware]
+@item -Wl,-[disable-dynamicbase | disable-nxcompat | disable-high-entropy-va | disable-tsaware]
+Set or clear PE (Windows) executable header hardening flags.  The
+@option{-Wl,-high-entropy-va} option is supported on x86-64 and ARM64 PE
+targets and implies @option{-Wl,-dynamicbase}.  Clearing dynamicbase also
+clears high-entropy-va.  When @option{-Wl,-dynamicbase} is used for an
+executable, TCC also enables base relocation emission for Windows ASLR.
+
 @item -Wl,-Bsymbolic
 Set DT_SYMBOLIC tag.
 

tcc.h

@@ -727,6 +727,15 @@ struct sym_attr {
 #endif
 };
 
+#ifdef TCC_TARGET_PE
+#define PE_IMAGE_FILE_RELOCS_STRIPPED            0x0001
+#define PE_IMAGE_FILE_LARGE_ADDRESS_AWARE        0x0020
+#define PE_DLLCHARACTERISTICS_HIGH_ENTROPY_VA    0x0020
+#define PE_DLLCHARACTERISTICS_DYNAMIC_BASE       0x0040
+#define PE_DLLCHARACTERISTICS_NX_COMPAT          0x0100
+#define PE_DLLCHARACTERISTICS_TERMINAL_SERVER_AWARE 0x8000
+#endif
+
 struct TCCState {
     unsigned char verbose; /* if true, display some information during compilation */
     unsigned char nostdinc; /* if true, no standard headers are added */
@@ -939,6 +948,8 @@ struct TCCState {
     /* PE info */
     int pe_subsystem;
     unsigned pe_characteristics;
+    unsigned pe_dll_characteristics;
+    unsigned pe_dll_characteristics_clear;
     unsigned pe_file_align;
     unsigned pe_stack_size;
     addr_t pe_imagebase;

tccpe.c

@@ -238,16 +238,16 @@ typedef struct _IMAGE_BASE_RELOCATION {
 #define IMAGE_SIZEOF_BASE_RELOCATION     8
 
 #ifndef IMAGE_DLLCHARACTERISTICS_HIGH_ENTROPY_VA
-#define IMAGE_DLLCHARACTERISTICS_HIGH_ENTROPY_VA 0x0020
+#define IMAGE_DLLCHARACTERISTICS_HIGH_ENTROPY_VA PE_DLLCHARACTERISTICS_HIGH_ENTROPY_VA
 #endif
 #ifndef IMAGE_DLLCHARACTERISTICS_DYNAMIC_BASE
-#define IMAGE_DLLCHARACTERISTICS_DYNAMIC_BASE 0x0040
+#define IMAGE_DLLCHARACTERISTICS_DYNAMIC_BASE PE_DLLCHARACTERISTICS_DYNAMIC_BASE
 #endif
 #ifndef IMAGE_DLLCHARACTERISTICS_NX_COMPAT
-#define IMAGE_DLLCHARACTERISTICS_NX_COMPAT 0x0100
+#define IMAGE_DLLCHARACTERISTICS_NX_COMPAT PE_DLLCHARACTERISTICS_NX_COMPAT
 #endif
 #ifndef IMAGE_DLLCHARACTERISTICS_TERMINAL_SERVER_AWARE
-#define IMAGE_DLLCHARACTERISTICS_TERMINAL_SERVER_AWARE 0x8000
+#define IMAGE_DLLCHARACTERISTICS_TERMINAL_SERVER_AWARE PE_DLLCHARACTERISTICS_TERMINAL_SERVER_AWARE
 #endif
 
 #define IMAGE_REL_BASED_ABSOLUTE         0
@@ -275,6 +275,21 @@ typedef struct _IMAGE_BASE_RELOCATION {
 #endif /* ndef IMAGE_NT_SIGNATURE */
 /* ----------------------------------------------------------- */
 
+static WORD pe_get_dll_characteristics(TCCState *s1)
+{
+    unsigned v = 0;
+
+#ifdef TCC_TARGET_ARM64
+    v = PE_DLLCHARACTERISTICS_HIGH_ENTROPY_VA |
+        PE_DLLCHARACTERISTICS_DYNAMIC_BASE |
+        PE_DLLCHARACTERISTICS_NX_COMPAT |
+        PE_DLLCHARACTERISTICS_TERMINAL_SERVER_AWARE;
+#endif
+    v |= s1->pe_dll_characteristics;
+    v &= ~s1->pe_dll_characteristics_clear;
+    return v;
+}
+
 #ifndef IMAGE_FILE_MACHINE_ARM64
 #define IMAGE_FILE_MACHINE_ARM64 0xAA64
 #endif
@@ -725,14 +740,7 @@ static int pe_write(struct pe_info *pe)
     0x00000200, /*DWORD   SizeOfHeaders; */
     0x00000000, /*DWORD   CheckSum; */
     0x0002, /*WORD    Subsystem; */
-#if defined(TCC_TARGET_ARM64)
-    IMAGE_DLLCHARACTERISTICS_HIGH_ENTROPY_VA |
-    IMAGE_DLLCHARACTERISTICS_DYNAMIC_BASE |
-    IMAGE_DLLCHARACTERISTICS_NX_COMPAT |
-    IMAGE_DLLCHARACTERISTICS_TERMINAL_SERVER_AWARE,
-#else
     0x0000, /*WORD    DllCharacteristics; */
-#endif
     0x00100000, /*DWORD   SizeOfStackReserve; */
     0x00001000, /*DWORD   SizeOfStackCommit; */
     0x00100000, /*DWORD   SizeOfHeapReserve; */
@@ -853,11 +861,14 @@ static int pe_write(struct pe_info *pe)
     pe_header.opthdr.SizeOfHeaders = pe->sizeofheaders;
     pe_header.opthdr.ImageBase = pe->imagebase;
     pe_header.opthdr.Subsystem = pe->subsystem;
+    pe_header.opthdr.DllCharacteristics = pe_get_dll_characteristics(s1);
     if (s1->pe_stack_size)
         pe_header.opthdr.SizeOfStackReserve = s1->pe_stack_size;
     if (PE_DLL == pe->type)
         pe_header.filehdr.Characteristics = CHARACTERISTICS_DLL;
     pe_header.filehdr.Characteristics |= s1->pe_characteristics;
+    if (pe->reloc)
+        pe_header.filehdr.Characteristics &= ~PE_IMAGE_FILE_RELOCS_STRIPPED;
 
     if (pe->coffsym) {
         pe_add_coffsym(pe);
@@ -1280,11 +1291,8 @@ static int pe_assign_addresses (struct pe_info *pe)
     Section *s;
     TCCState *s1 = pe->s1;
 
-    if (PE_DLL == pe->type
+    if (PE_DLL == pe->type ||
-#ifdef TCC_TARGET_ARM64
+        (pe_get_dll_characteristics(s1) & PE_DLLCHARACTERISTICS_DYNAMIC_BASE))
-        || PE_EXE == pe->type || PE_GUI == pe->type
-#endif
-        )
         pe->reloc = new_section(s1, ".reloc", SHT_PROGBITS, 0);
     //pe->thunk = new_section(s1, ".iedat", SHT_PROGBITS, SHF_ALLOC);