xnu-7195.50.7.100.1.tar.gz

[apple/xnu.git] / libkern / ptrauth_utils.c

diff --git a/libkern/ptrauth_utils.c b/libkern/ptrauth_utils.c
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+++ b/libkern/ptrauth_utils.c
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+/*
+ * 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
+ *
+ */
+ptrauth_generic_signature_t
+ptrauth_utils_sign_blob_generic(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 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(*(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) {
+               memcpy(&trailing, ptr, ntrailing);
+               sig = ptrauth_sign_generic_data(trailing, sig);
+       }
+
+       return sig;
+}
+
+/*
+ * ptrauth_utils_auth_blob_generic
+ *
+ * Authenticate signature produced by ptrauth_utils_sign_blob_generic
+ */
+void
+ptrauth_utils_auth_blob_generic(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