Re: [PATCH v2] peflags: add support for IMAGE_DLLCHARACTERISTICS_GUARD_CF

[Christoph Reiter via Cygwin-apps]

On Tue, Apr 18, 2023 at 9:44 AM Corinna Vinschen
 wrote:
> Pash pushed.  I new rebase 4.6.3 release with your patch is just
> building.

Thanks!

[PATCH v2] peflags: add support for IMAGE_DLLCHARACTERISTICS_GUARD_CF

[Christoph Reiter via Cygwin-apps]

This allows for setting, clearing, and displaying the value of the
"control flow guard" dll characteristics flag.

The flag for MSVC is called "/guard:cf" and the macro ends with "GUARD_CF".
To keep things consistent, it would make sense to name the option "guard-cf".
However, there's already "-c"/"control-flow-guard" in genpeimg for this flag,
and genpeimg shares all other options with peflags so far.
So, follow genpeimg and go with "-c" and "--control-flow-guard".

This is motivated by mingw-w64 and llvm v16 gaining support for
CFG (Control Flow Guard).
---
Renamed the option from -g/--guard-cf to -c/--control-flow-guard

 peflags.c | 12 ++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/peflags.c b/peflags.c
index b1cd7a8..93eaa0b 100644
--- a/peflags.c
+++ b/peflags.c
@@ -121,7 +121,7 @@ static const symbolic_flags_t pe_symbolic_flags[] = {
   CF(0x0800, no-bind),
 /*CF(0x1000, reserved_0x1000),*/
   CF(0x2000, wdmdriver),
-/*CF(0x4000, reserved_0x4000),*/
+  CF(0x4000, control-flow-guard),
   CF(0x8000, tsaware),
   {0, 0, 0}
 };
@@ -182,6 +182,7 @@ sizeof_values_t sizeof_vals[5] = {
 static struct option long_options[] = {
   {"dynamicbase",  optional_argument, NULL, 'd'},
   {"high-entropy-va", optional_argument, NULL, 'e'},
+  {"control-flow-guard", optional_argument, NULL, 'c'},
   {"forceinteg",   optional_argument, NULL, 'f'},
   {"nxcompat", optional_argument, NULL, 'n'},
   {"no-isolation", optional_argument, NULL, 'i'},
@@ -204,7 +205,7 @@ static struct option long_options[] = {
   {NULL, no_argument, NULL, 0}
 };
 static const char *short_options
-   = "d::e::f::n::i::s::b::W::t::w::l::S::x::X::y::Y::z::T:vhV";
+   = "d::e::c::f::n::i::s::b::W::t::w::l::S::x::X::y::Y::z::T:vhV";
 
 static void short_usage (FILE *f);
 static void help (FILE *f);
@@ -706,6 +707,11 @@ parse_args (int argc, char *argv[])
 optarg,
 IMAGE_DLLCHARACTERISTICS_HIGH_ENTROPY_VA);
  break;
+   case 'c':
+ handle_pe_flag_option (long_options[option_index].name,
+optarg,
+IMAGE_DLLCHARACTERISTICS_GUARD_CF);
+ break;
case 'n':
  handle_pe_flag_option (long_options[option_index].name,
 optarg,
@@ -1079,6 +1085,8 @@ help (FILE *f)
 "  -e,\n"
 "  --high-entropy-va  [BOOL]   Image is compatible with 64-bit address space\n"
 "  layout randomization (ASLR).\n"
+"  -c,\n"
+"  --control-flow-guard [BOOL] Image supports Control Flow Guard.\n"
 "  -f, --forceinteg   [BOOL]   Code integrity checks are enforced.\n"
 "  -n, --nxcompat [BOOL]   Image is compatible with data execution\n"
 "  prevention (DEP).\n"
-- 
2.40.0

Re: [PATCH] peflags: add support for IMAGE_DLLCHARACTERISTICS_GUARD_CF

[Christoph Reiter via Cygwin-apps]

Jeremy noted that an option already exists in genpeimage [0] but with
a different name, which I wasn't aware of: -c/control-flow-guard,
instead of -g/guard-cf which I used here. I'm open to making them
match.

[0] 
https://github.com/mingw-w64/mingw-w64/blob/70ec1e0de44f3cbed2064c08e1620ff0a7916cd1/mingw-w64-tools/genpeimg/src/genpeimg.c#L84

[PATCH] peflags: add support for IMAGE_DLLCHARACTERISTICS_GUARD_CF

[Christoph Reiter via Cygwin-apps]

This allows for setting, clearing, and displaying the value of the
"control flow guard" dll characteristics flag.

For the option naming something like cfguard would probably be
easier to understand, but the MSVC flag is "/guard:cf" and the macro
contains GUARD_CF, so use "guard-cf" for consistency.

This is motivated by mingw-w64 and llvm v16 gaining support for
CFG (Control Flow Guard).
---
 peflags.c | 11 +--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/peflags.c b/peflags.c
index b1cd7a8..83ce48e 100644
--- a/peflags.c
+++ b/peflags.c
@@ -121,7 +121,7 @@ static const symbolic_flags_t pe_symbolic_flags[] = {
   CF(0x0800, no-bind),
 /*CF(0x1000, reserved_0x1000),*/
   CF(0x2000, wdmdriver),
-/*CF(0x4000, reserved_0x4000),*/
+  CF(0x4000, guard-cf),
   CF(0x8000, tsaware),
   {0, 0, 0}
 };
@@ -182,6 +182,7 @@ sizeof_values_t sizeof_vals[5] = {
 static struct option long_options[] = {
   {"dynamicbase",  optional_argument, NULL, 'd'},
   {"high-entropy-va", optional_argument, NULL, 'e'},
+  {"guard-cf", optional_argument, NULL, 'g'},
   {"forceinteg",   optional_argument, NULL, 'f'},
   {"nxcompat", optional_argument, NULL, 'n'},
   {"no-isolation", optional_argument, NULL, 'i'},
@@ -204,7 +205,7 @@ static struct option long_options[] = {
   {NULL, no_argument, NULL, 0}
 };
 static const char *short_options
-   = "d::e::f::n::i::s::b::W::t::w::l::S::x::X::y::Y::z::T:vhV";
+   = "d::e::g::f::n::i::s::b::W::t::w::l::S::x::X::y::Y::z::T:vhV";
 
 static void short_usage (FILE *f);
 static void help (FILE *f);
@@ -706,6 +707,11 @@ parse_args (int argc, char *argv[])
 optarg,
 IMAGE_DLLCHARACTERISTICS_HIGH_ENTROPY_VA);
  break;
+   case 'g':
+ handle_pe_flag_option (long_options[option_index].name,
+optarg,
+IMAGE_DLLCHARACTERISTICS_GUARD_CF);
+ break;
case 'n':
  handle_pe_flag_option (long_options[option_index].name,
 optarg,
@@ -1079,6 +1085,7 @@ help (FILE *f)
 "  -e,\n"
 "  --high-entropy-va  [BOOL]   Image is compatible with 64-bit address space\n"
 "  layout randomization (ASLR).\n"
+"  -g, --guard-cf [BOOL]   Image supports Control Flow Guard.\n"
 "  -f, --forceinteg   [BOOL]   Code integrity checks are enforced.\n"
 "  -n, --nxcompat [BOOL]   Image is compatible with data execution\n"
 "  prevention (DEP).\n"
-- 
2.40.0