darling-xnu/libkern/ptrauth_utils.c
2023-05-16 21:41:14 -07:00

120 lines
3.7 KiB
C

/*
* Copyright (c) 2020 Apple Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. The rights granted to you under the License
* may not be used to create, or enable the creation or redistribution of,
* unlawful or unlicensed copies of an Apple operating system, or to
* circumvent, violate, or enable the circumvention or violation of, any
* terms of an Apple operating system software license agreement.
*
* Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*/
#include <IOKit/IOLib.h>
#include <kern/debug.h> // for panic()
#include <libkern/ptrauth_utils.h>
#if __has_feature(ptrauth_calls)
/*
* ptrauth_utils_sign_blob_generic
*
* Sign a blob of data with the GA key
*
*/
__attribute__((noinline))
ptrauth_generic_signature_t
ptrauth_utils_sign_blob_generic(const void * ptr, size_t len_bytes, uint64_t data, int flags)
{
ptrauth_generic_signature_t sig = 0;
uint64_t rounds = len_bytes / sizeof(uintptr_t);
size_t ntrailing = len_bytes % sizeof(uintptr_t);
uintptr_t trailing = 0;
if (ptr == NULL) {
return 0;
}
/* If address diversification is requested, mix the blob address with the salt */
if (flags & PTRAUTH_ADDR_DIVERSIFY) {
data ^= (uint64_t)ptr;
}
/* First round adds ptrauth_utils_sign_blob_generic discrimination. */
sig = ptrauth_sign_generic_data(sig, ptrauth_string_discriminator("ptrauth_utils_sign_blob_generic-prologue") | 0x01);
/* Second round adds salt */
sig = ptrauth_sign_generic_data(sig, data);
/* Calculate an additive signature of the buffer */
for (uint64_t i = 0; i < rounds; i++) {
sig = ptrauth_sign_generic_data(*(const uintptr_t *)ptr, sig);
ptr += sizeof(uintptr_t);
}
/* ptrauth_sign_generic_data operates on pointer-sized values only,
* so we need to handle trailing bytes for the non-pointer-aligned case */
if (ntrailing) {
for (int i = 0; i < ntrailing; i++) {
((uint8_t *)&trailing)[i] = ((const uint8_t *)ptr)[i];
}
sig = ptrauth_sign_generic_data(trailing, sig);
}
/* Final round to add an additional cookie */
sig = ptrauth_sign_generic_data(sig, ptrauth_string_discriminator("ptrauth_utils_sign_blob_generic-epilogue") | 0x01);
return sig;
}
/*
* ptrauth_utils_auth_blob_generic
*
* Authenticate signature produced by ptrauth_utils_sign_blob_generic
*/
__attribute__((noinline))
void
ptrauth_utils_auth_blob_generic(const void * ptr, size_t len_bytes, uint64_t data, int flags, ptrauth_generic_signature_t signature)
{
ptrauth_generic_signature_t calculated_signature = 0;
if (ptr == NULL) {
if (flags & PTRAUTH_NON_NULL) {
panic("ptrauth_utils_auth_blob_generic: ptr must not be NULL");
} else {
return;
}
}
if ((calculated_signature = ptrauth_utils_sign_blob_generic(ptr, len_bytes, data, flags)) == signature) {
return;
} else {
panic("signature mismatch for %lu bytes at %p, calculated %lx vs %lx", len_bytes,
ptr,
calculated_signature,
signature);
}
}
#endif //!ptrauth_calls