Merge #17787: scripts: add MACHO PIE check to security-check.py

7c9e821 scripts: add MACHO NOUNDEFS check to security-check.py (fanquake)
4ca92dc scripts: add MACHO PIE check to security-check.py (fanquake)

Pull request description:

  This uses `otool -vh` to print the mach header and look for the `PIE` flag:
  ```bash
  otool -vh src/bitcoind
  Mach header
        magic cputype cpusubtype  caps    filetype ncmds sizeofcmds      flags
  MH_MAGIC_64  X86_64        ALL LIB64     EXECUTE    24       2544   NOUNDEFS DYLDLINK TWOLEVEL WEAK_DEFINES BINDS_TO_WEAK PIE
  ```

  From [`mach-o/loader.h`](https://opensource.apple.com/source/cctools/cctools-927.0.2/include/mach-o/loader.h.auto.html):
  ```c
  #define	MH_PIE 0x200000			/* When this bit is set, the OS will
  					   load the main executable at a
  					   random address.  Only used in
  					   MH_EXECUTE filetypes. */
  ```

ACKs for top commit:
  laanwj:
    code review ACK 7c9e821

Tree-SHA512: 5ba2f60440d0e31c70371a355c91ca4f723d80f7287d04e2098bf5b11892cc74216ff8f1454603c4db9675d4f7983614843b992b8dcfca0309aadf2aa7ab2e4b

Author: laanwj

contrib/devtools/README.md

@@ -98,7 +98,7 @@ repository (requires pngcrush).
 security-check.py and test-security-check.py
 ============================================
 
-Perform basic ELF security checks on a series of executables.
+Perform basic security checks on a series of executables.
 
 symbol-check.py
 ===============

contrib/devtools/security-check.py

@@ -3,17 +3,18 @@
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 '''
-Perform basic ELF security checks on a series of executables.
+Perform basic security checks on a series of executables.
 Exit status will be 0 if successful, and the program will be silent.
 Otherwise the exit status will be 1 and it will log which executables failed which checks.
-Needs `readelf` (for ELF) and `objdump` (for PE).
+Needs `readelf` (for ELF), `objdump` (for PE) and `otool` (for MACHO).
 '''
 import subprocess
 import sys
 import os
 
 READELF_CMD = os.getenv('READELF', '/usr/bin/readelf')
 OBJDUMP_CMD = os.getenv('OBJDUMP', '/usr/bin/objdump')
+OTOOL_CMD = os.getenv('OTOOL', '/usr/bin/otool')
 NONFATAL = {} # checks which are non-fatal for now but only generate a warning
 
 def check_ELF_PIE(executable):
@@ -162,6 +163,40 @@ def check_PE_NX(executable):
     (arch,bits) = get_PE_dll_characteristics(executable)
     return (bits & IMAGE_DLL_CHARACTERISTICS_NX_COMPAT) == IMAGE_DLL_CHARACTERISTICS_NX_COMPAT
 
+def get_MACHO_executable_flags(executable):
+    p = subprocess.Popen([OTOOL_CMD, '-vh', executable], stdout=subprocess.PIPE, stderr=subprocess.PIPE, stdin=subprocess.PIPE, universal_newlines=True)
+    (stdout, stderr) = p.communicate()
+    if p.returncode:
+        raise IOError('Error opening file')
+
+    flags = []
+    for line in stdout.splitlines():
+        tokens = line.split()
+        # filter first two header lines
+        if 'magic' in tokens or 'Mach' in tokens:
+            continue
+        # filter ncmds and sizeofcmds values
+        flags += [t for t in tokens if not t.isdigit()]
+    return flags
+
+def check_MACHO_PIE(executable) -> bool:
+    '''
+    Check for position independent executable (PIE), allowing for address space randomization.
+    '''
+    flags = get_MACHO_executable_flags(executable)
+    if 'PIE' in flags:
+        return True
+    return False
+
+def check_MACHO_NOUNDEFS(executable) -> bool:
+    '''
+    Check for no undefined references.
+    '''
+    flags = get_MACHO_executable_flags(executable)
+    if 'NOUNDEFS' in flags:
+        return True
+    return False
+
 CHECKS = {
 'ELF': [
     ('PIE', check_ELF_PIE),
@@ -173,6 +208,10 @@ def check_PE_NX(executable):
     ('DYNAMIC_BASE', check_PE_DYNAMIC_BASE),
     ('HIGH_ENTROPY_VA', check_PE_HIGH_ENTROPY_VA),
     ('NX', check_PE_NX)
+],
+'MACHO': [
+    ('PIE', check_MACHO_PIE),
+    ('NOUNDEFS', check_MACHO_NOUNDEFS),
 ]
 }
 
@@ -183,6 +222,8 @@ def identify_executable(executable):
         return 'PE'
     elif magic.startswith(b'\x7fELF'):
         return 'ELF'
+    elif magic.startswith(b'\xcf\xfa'):
+        return 'MACHO'
     return None
 
 if __name__ == '__main__':

contrib/gitian-descriptors/gitian-osx.yml

@@ -137,6 +137,7 @@ script: |
 
     CONFIG_SITE=${BASEPREFIX}/${i}/share/config.site ./configure --prefix=/ --disable-ccache --disable-maintainer-mode --disable-dependency-tracking ${CONFIGFLAGS}
     make ${MAKEOPTS}
+    make ${MAKEOPTS} -C src check-security
     make install-strip DESTDIR=${INSTALLPATH}
 
     make osx_volname

src/Makefile.am

@@ -710,7 +710,7 @@ endif
 check-security: $(bin_PROGRAMS)
 if HARDEN
 	@echo "Checking binary security..."
-	$(AM_V_at) READELF=$(READELF) OBJDUMP=$(OBJDUMP) $(PYTHON) $(top_srcdir)/contrib/devtools/security-check.py < $(bin_PROGRAMS)
+	$(AM_V_at) READELF=$(READELF) OBJDUMP=$(OBJDUMP) OTOOL=$(OTOOL) $(PYTHON) $(top_srcdir)/contrib/devtools/security-check.py < $(bin_PROGRAMS)
 endif
 
 if EMBEDDED_LEVELDB