ok
Mini Shell
import contextlib
import ctypes
import platform
import ssl
import typing
from ctypes import (
CDLL,
POINTER,
c_bool,
c_char_p,
c_int32,
c_long,
c_uint32,
c_ulong,
c_void_p,
)
from ctypes.util import find_library
from ._ssl_constants import _set_ssl_context_verify_mode
_mac_version = platform.mac_ver()[0]
_mac_version_info = tuple(map(int, _mac_version.split(".")))
if _mac_version_info < (10, 8):
raise ImportError(
f"Only OS X 10.8 and newer are supported, not {_mac_version_info[0]}.{_mac_version_info[1]}"
)
def _load_cdll(name: str, macos10_16_path: str) -> CDLL:
"""Loads a CDLL by name, falling back to known path on 10.16+"""
try:
# Big Sur is technically 11 but we use 10.16 due to the Big Sur
# beta being labeled as 10.16.
path: str | None
if _mac_version_info >= (10, 16):
path = macos10_16_path
else:
path = find_library(name)
if not path:
raise OSError # Caught and reraised as 'ImportError'
return CDLL(path, use_errno=True)
except OSError:
raise ImportError(f"The library {name} failed to load") from None
Security = _load_cdll(
"Security", "/System/Library/Frameworks/Security.framework/Security"
)
CoreFoundation = _load_cdll(
"CoreFoundation",
"/System/Library/Frameworks/CoreFoundation.framework/CoreFoundation",
)
Boolean = c_bool
CFIndex = c_long
CFStringEncoding = c_uint32
CFData = c_void_p
CFString = c_void_p
CFArray = c_void_p
CFMutableArray = c_void_p
CFError = c_void_p
CFType = c_void_p
CFTypeID = c_ulong
CFTypeRef = POINTER(CFType)
CFAllocatorRef = c_void_p
OSStatus = c_int32
CFErrorRef = POINTER(CFError)
CFDataRef = POINTER(CFData)
CFStringRef = POINTER(CFString)
CFArrayRef = POINTER(CFArray)
CFMutableArrayRef = POINTER(CFMutableArray)
CFArrayCallBacks = c_void_p
CFOptionFlags = c_uint32
SecCertificateRef = POINTER(c_void_p)
SecPolicyRef = POINTER(c_void_p)
SecTrustRef = POINTER(c_void_p)
SecTrustResultType = c_uint32
SecTrustOptionFlags = c_uint32
try:
Security.SecCertificateCreateWithData.argtypes = [CFAllocatorRef, CFDataRef]
Security.SecCertificateCreateWithData.restype = SecCertificateRef
Security.SecCertificateCopyData.argtypes = [SecCertificateRef]
Security.SecCertificateCopyData.restype = CFDataRef
Security.SecCopyErrorMessageString.argtypes = [OSStatus, c_void_p]
Security.SecCopyErrorMessageString.restype = CFStringRef
Security.SecTrustSetAnchorCertificates.argtypes = [SecTrustRef, CFArrayRef]
Security.SecTrustSetAnchorCertificates.restype = OSStatus
Security.SecTrustSetAnchorCertificatesOnly.argtypes = [SecTrustRef, Boolean]
Security.SecTrustSetAnchorCertificatesOnly.restype = OSStatus
Security.SecTrustEvaluate.argtypes = [SecTrustRef, POINTER(SecTrustResultType)]
Security.SecTrustEvaluate.restype = OSStatus
Security.SecPolicyCreateRevocation.argtypes = [CFOptionFlags]
Security.SecPolicyCreateRevocation.restype = SecPolicyRef
Security.SecPolicyCreateSSL.argtypes = [Boolean, CFStringRef]
Security.SecPolicyCreateSSL.restype = SecPolicyRef
Security.SecTrustCreateWithCertificates.argtypes = [
CFTypeRef,
CFTypeRef,
POINTER(SecTrustRef),
]
Security.SecTrustCreateWithCertificates.restype = OSStatus
Security.SecTrustGetTrustResult.argtypes = [
SecTrustRef,
POINTER(SecTrustResultType),
]
Security.SecTrustGetTrustResult.restype = OSStatus
Security.SecTrustRef = SecTrustRef # type: ignore[attr-defined]
Security.SecTrustResultType = SecTrustResultType # type: ignore[attr-defined]
Security.OSStatus = OSStatus # type: ignore[attr-defined]
kSecRevocationUseAnyAvailableMethod = 3
kSecRevocationRequirePositiveResponse = 8
CoreFoundation.CFRelease.argtypes = [CFTypeRef]
CoreFoundation.CFRelease.restype = None
CoreFoundation.CFGetTypeID.argtypes = [CFTypeRef]
CoreFoundation.CFGetTypeID.restype = CFTypeID
CoreFoundation.CFStringCreateWithCString.argtypes = [
CFAllocatorRef,
c_char_p,
CFStringEncoding,
]
CoreFoundation.CFStringCreateWithCString.restype = CFStringRef
CoreFoundation.CFStringGetCStringPtr.argtypes = [CFStringRef, CFStringEncoding]
CoreFoundation.CFStringGetCStringPtr.restype = c_char_p
CoreFoundation.CFStringGetCString.argtypes = [
CFStringRef,
c_char_p,
CFIndex,
CFStringEncoding,
]
CoreFoundation.CFStringGetCString.restype = c_bool
CoreFoundation.CFDataCreate.argtypes = [CFAllocatorRef, c_char_p, CFIndex]
CoreFoundation.CFDataCreate.restype = CFDataRef
CoreFoundation.CFDataGetLength.argtypes = [CFDataRef]
CoreFoundation.CFDataGetLength.restype = CFIndex
CoreFoundation.CFDataGetBytePtr.argtypes = [CFDataRef]
CoreFoundation.CFDataGetBytePtr.restype = c_void_p
CoreFoundation.CFArrayCreate.argtypes = [
CFAllocatorRef,
POINTER(CFTypeRef),
CFIndex,
CFArrayCallBacks,
]
CoreFoundation.CFArrayCreate.restype = CFArrayRef
CoreFoundation.CFArrayCreateMutable.argtypes = [
CFAllocatorRef,
CFIndex,
CFArrayCallBacks,
]
CoreFoundation.CFArrayCreateMutable.restype = CFMutableArrayRef
CoreFoundation.CFArrayAppendValue.argtypes = [CFMutableArrayRef, c_void_p]
CoreFoundation.CFArrayAppendValue.restype = None
CoreFoundation.CFArrayGetCount.argtypes = [CFArrayRef]
CoreFoundation.CFArrayGetCount.restype = CFIndex
CoreFoundation.CFArrayGetValueAtIndex.argtypes = [CFArrayRef, CFIndex]
CoreFoundation.CFArrayGetValueAtIndex.restype = c_void_p
CoreFoundation.CFErrorGetCode.argtypes = [CFErrorRef]
CoreFoundation.CFErrorGetCode.restype = CFIndex
CoreFoundation.CFErrorCopyDescription.argtypes = [CFErrorRef]
CoreFoundation.CFErrorCopyDescription.restype = CFStringRef
CoreFoundation.kCFAllocatorDefault = CFAllocatorRef.in_dll( # type: ignore[attr-defined]
CoreFoundation, "kCFAllocatorDefault"
)
CoreFoundation.kCFTypeArrayCallBacks = c_void_p.in_dll( # type: ignore[attr-defined]
CoreFoundation, "kCFTypeArrayCallBacks"
)
CoreFoundation.CFTypeRef = CFTypeRef # type: ignore[attr-defined]
CoreFoundation.CFArrayRef = CFArrayRef # type: ignore[attr-defined]
CoreFoundation.CFStringRef = CFStringRef # type: ignore[attr-defined]
CoreFoundation.CFErrorRef = CFErrorRef # type: ignore[attr-defined]
except AttributeError:
raise ImportError("Error initializing ctypes") from None
def _handle_osstatus(result: OSStatus, _: typing.Any, args: typing.Any) -> typing.Any:
"""
Raises an error if the OSStatus value is non-zero.
"""
if int(result) == 0:
return args
# Returns a CFString which we need to transform
# into a UTF-8 Python string.
error_message_cfstring = None
try:
error_message_cfstring = Security.SecCopyErrorMessageString(result, None)
# First step is convert the CFString into a C string pointer.
# We try the fast no-copy way first.
error_message_cfstring_c_void_p = ctypes.cast(
error_message_cfstring, ctypes.POINTER(ctypes.c_void_p)
)
message = CoreFoundation.CFStringGetCStringPtr(
error_message_cfstring_c_void_p, CFConst.kCFStringEncodingUTF8
)
# Quoting the Apple dev docs:
#
# "A pointer to a C string or NULL if the internal
# storage of theString does not allow this to be
# returned efficiently."
#
# So we need to get our hands dirty.
if message is None:
buffer = ctypes.create_string_buffer(1024)
result = CoreFoundation.CFStringGetCString(
error_message_cfstring_c_void_p,
buffer,
1024,
CFConst.kCFStringEncodingUTF8,
)
if not result:
raise OSError("Error copying C string from CFStringRef")
message = buffer.value
finally:
if error_message_cfstring is not None:
CoreFoundation.CFRelease(error_message_cfstring)
# If no message can be found for this status we come
# up with a generic one that forwards the status code.
if message is None or message == "":
message = f"SecureTransport operation returned a non-zero OSStatus: {result}"
raise ssl.SSLError(message)
Security.SecTrustCreateWithCertificates.errcheck = _handle_osstatus # type: ignore[assignment]
Security.SecTrustSetAnchorCertificates.errcheck = _handle_osstatus # type: ignore[assignment]
Security.SecTrustGetTrustResult.errcheck = _handle_osstatus # type: ignore[assignment]
class CFConst:
"""CoreFoundation constants"""
kCFStringEncodingUTF8 = CFStringEncoding(0x08000100)
errSecIncompleteCertRevocationCheck = -67635
errSecHostNameMismatch = -67602
errSecCertificateExpired = -67818
errSecNotTrusted = -67843
def _bytes_to_cf_data_ref(value: bytes) -> CFDataRef: # type: ignore[valid-type]
return CoreFoundation.CFDataCreate( # type: ignore[no-any-return]
CoreFoundation.kCFAllocatorDefault, value, len(value)
)
def _bytes_to_cf_string(value: bytes) -> CFString:
"""
Given a Python binary data, create a CFString.
The string must be CFReleased by the caller.
"""
c_str = ctypes.c_char_p(value)
cf_str = CoreFoundation.CFStringCreateWithCString(
CoreFoundation.kCFAllocatorDefault,
c_str,
CFConst.kCFStringEncodingUTF8,
)
return cf_str # type: ignore[no-any-return]
def _cf_string_ref_to_str(cf_string_ref: CFStringRef) -> str | None: # type: ignore[valid-type]
"""
Creates a Unicode string from a CFString object. Used entirely for error
reporting.
Yes, it annoys me quite a lot that this function is this complex.
"""
string = CoreFoundation.CFStringGetCStringPtr(
cf_string_ref, CFConst.kCFStringEncodingUTF8
)
if string is None:
buffer = ctypes.create_string_buffer(1024)
result = CoreFoundation.CFStringGetCString(
cf_string_ref, buffer, 1024, CFConst.kCFStringEncodingUTF8
)
if not result:
raise OSError("Error copying C string from CFStringRef")
string = buffer.value
if string is not None:
string = string.decode("utf-8")
return string # type: ignore[no-any-return]
def _der_certs_to_cf_cert_array(certs: list[bytes]) -> CFMutableArrayRef: # type: ignore[valid-type]
"""Builds a CFArray of SecCertificateRefs from a list of DER-encoded certificates.
Responsibility of the caller to call CoreFoundation.CFRelease on the CFArray.
"""
cf_array = CoreFoundation.CFArrayCreateMutable(
CoreFoundation.kCFAllocatorDefault,
0,
ctypes.byref(CoreFoundation.kCFTypeArrayCallBacks),
)
if not cf_array:
raise MemoryError("Unable to allocate memory!")
for cert_data in certs:
cf_data = None
sec_cert_ref = None
try:
cf_data = _bytes_to_cf_data_ref(cert_data)
sec_cert_ref = Security.SecCertificateCreateWithData(
CoreFoundation.kCFAllocatorDefault, cf_data
)
CoreFoundation.CFArrayAppendValue(cf_array, sec_cert_ref)
finally:
if cf_data:
CoreFoundation.CFRelease(cf_data)
if sec_cert_ref:
CoreFoundation.CFRelease(sec_cert_ref)
return cf_array # type: ignore[no-any-return]
@contextlib.contextmanager
def _configure_context(ctx: ssl.SSLContext) -> typing.Iterator[None]:
check_hostname = ctx.check_hostname
verify_mode = ctx.verify_mode
ctx.check_hostname = False
_set_ssl_context_verify_mode(ctx, ssl.CERT_NONE)
try:
yield
finally:
ctx.check_hostname = check_hostname
_set_ssl_context_verify_mode(ctx, verify_mode)
def _verify_peercerts_impl(
ssl_context: ssl.SSLContext,
cert_chain: list[bytes],
server_hostname: str | None = None,
) -> None:
certs = None
policies = None
trust = None
cf_error = None
try:
if server_hostname is not None:
cf_str_hostname = None
try:
cf_str_hostname = _bytes_to_cf_string(server_hostname.encode("ascii"))
ssl_policy = Security.SecPolicyCreateSSL(True, cf_str_hostname)
finally:
if cf_str_hostname:
CoreFoundation.CFRelease(cf_str_hostname)
else:
ssl_policy = Security.SecPolicyCreateSSL(True, None)
policies = ssl_policy
if ssl_context.verify_flags & ssl.VERIFY_CRL_CHECK_CHAIN:
# Add explicit policy requiring positive revocation checks
policies = CoreFoundation.CFArrayCreateMutable(
CoreFoundation.kCFAllocatorDefault,
0,
ctypes.byref(CoreFoundation.kCFTypeArrayCallBacks),
)
CoreFoundation.CFArrayAppendValue(policies, ssl_policy)
CoreFoundation.CFRelease(ssl_policy)
revocation_policy = Security.SecPolicyCreateRevocation(
kSecRevocationUseAnyAvailableMethod
| kSecRevocationRequirePositiveResponse
)
CoreFoundation.CFArrayAppendValue(policies, revocation_policy)
CoreFoundation.CFRelease(revocation_policy)
elif ssl_context.verify_flags & ssl.VERIFY_CRL_CHECK_LEAF:
raise NotImplementedError("VERIFY_CRL_CHECK_LEAF not implemented for macOS")
certs = None
try:
certs = _der_certs_to_cf_cert_array(cert_chain)
# Now that we have certificates loaded and a SecPolicy
# we can finally create a SecTrust object!
trust = Security.SecTrustRef()
Security.SecTrustCreateWithCertificates(
certs, policies, ctypes.byref(trust)
)
finally:
# The certs are now being held by SecTrust so we can
# release our handles for the array.
if certs:
CoreFoundation.CFRelease(certs)
# If there are additional trust anchors to load we need to transform
# the list of DER-encoded certificates into a CFArray. Otherwise
# pass 'None' to signal that we only want system / fetched certificates.
ctx_ca_certs_der: list[bytes] | None = ssl_context.get_ca_certs(
binary_form=True
)
if ctx_ca_certs_der:
ctx_ca_certs = None
try:
ctx_ca_certs = _der_certs_to_cf_cert_array(cert_chain)
Security.SecTrustSetAnchorCertificates(trust, ctx_ca_certs)
finally:
if ctx_ca_certs:
CoreFoundation.CFRelease(ctx_ca_certs)
else:
Security.SecTrustSetAnchorCertificates(trust, None)
cf_error = CoreFoundation.CFErrorRef()
sec_trust_eval_result = Security.SecTrustEvaluateWithError(
trust, ctypes.byref(cf_error)
)
# sec_trust_eval_result is a bool (0 or 1)
# where 1 means that the certs are trusted.
if sec_trust_eval_result == 1:
is_trusted = True
elif sec_trust_eval_result == 0:
is_trusted = False
else:
raise ssl.SSLError(
f"Unknown result from Security.SecTrustEvaluateWithError: {sec_trust_eval_result!r}"
)
cf_error_code = 0
if not is_trusted:
cf_error_code = CoreFoundation.CFErrorGetCode(cf_error)
# If the error is a known failure that we're
# explicitly okay with from SSLContext configuration
# we can set is_trusted accordingly.
if ssl_context.verify_mode != ssl.CERT_REQUIRED and (
cf_error_code == CFConst.errSecNotTrusted
or cf_error_code == CFConst.errSecCertificateExpired
):
is_trusted = True
elif (
not ssl_context.check_hostname
and cf_error_code == CFConst.errSecHostNameMismatch
):
is_trusted = True
# If we're still not trusted then we start to
# construct and raise the SSLCertVerificationError.
if not is_trusted:
cf_error_string_ref = None
try:
cf_error_string_ref = CoreFoundation.CFErrorCopyDescription(cf_error)
# Can this ever return 'None' if there's a CFError?
cf_error_message = (
_cf_string_ref_to_str(cf_error_string_ref)
or "Certificate verification failed"
)
# TODO: Not sure if we need the SecTrustResultType for anything?
# We only care whether or not it's a success or failure for now.
sec_trust_result_type = Security.SecTrustResultType()
Security.SecTrustGetTrustResult(
trust, ctypes.byref(sec_trust_result_type)
)
err = ssl.SSLCertVerificationError(cf_error_message)
err.verify_message = cf_error_message
err.verify_code = cf_error_code
raise err
finally:
if cf_error_string_ref:
CoreFoundation.CFRelease(cf_error_string_ref)
finally:
if policies:
CoreFoundation.CFRelease(policies)
if trust:
CoreFoundation.CFRelease(trust)
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