+++ /dev/null
-From 6e34f618d37ddbb5854c42e2ad4fca83492fa7b7 Mon Sep 17 00:00:00 2001
-From: Jouni Malinen <jouni@codeaurora.org>
-Date: Wed, 27 Feb 2019 18:38:30 +0200
-Subject: [PATCH 02/14] Add helper functions for constant time operations
-
-These functions can be used to help implement constant time operations
-for various cryptographic operations that must minimize externally
-observable differences in processing (both in timing and also in
-internal cache use, etc.).
-
-This is related to CVE-2019-9494 and CVE-2019-9495.
-
-Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
----
- src/utils/const_time.h | 191 +++++++++++++++++++++++++++++++++++++++++++++++++
- 1 file changed, 191 insertions(+)
- create mode 100644 src/utils/const_time.h
-
---- /dev/null
-+++ b/src/utils/const_time.h
-@@ -0,0 +1,191 @@
-+/*
-+ * Helper functions for constant time operations
-+ * Copyright (c) 2019, The Linux Foundation
-+ *
-+ * This software may be distributed under the terms of the BSD license.
-+ * See README for more details.
-+ *
-+ * These helper functions can be used to implement logic that needs to minimize
-+ * externally visible differences in execution path by avoiding use of branches,
-+ * avoiding early termination or other time differences, and forcing same memory
-+ * access pattern regardless of values.
-+ */
-+
-+#ifndef CONST_TIME_H
-+#define CONST_TIME_H
-+
-+
-+#if defined(__clang__)
-+#define NO_UBSAN_UINT_OVERFLOW \
-+ __attribute__((no_sanitize("unsigned-integer-overflow")))
-+#else
-+#define NO_UBSAN_UINT_OVERFLOW
-+#endif
-+
-+
-+/**
-+ * const_time_fill_msb - Fill all bits with MSB value
-+ * @val: Input value
-+ * Returns: Value with all the bits set to the MSB of the input val
-+ */
-+static inline unsigned int const_time_fill_msb(unsigned int val)
-+{
-+ /* Move the MSB to LSB and multiple by -1 to fill in all bits. */
-+ return (val >> (sizeof(val) * 8 - 1)) * ~0U;
-+}
-+
-+
-+/* Returns: -1 if val is zero; 0 if val is not zero */
-+static inline unsigned int const_time_is_zero(unsigned int val)
-+ NO_UBSAN_UINT_OVERFLOW
-+{
-+ /* Set MSB to 1 for 0 and fill rest of bits with the MSB value */
-+ return const_time_fill_msb(~val & (val - 1));
-+}
-+
-+
-+/* Returns: -1 if a == b; 0 if a != b */
-+static inline unsigned int const_time_eq(unsigned int a, unsigned int b)
-+{
-+ return const_time_is_zero(a ^ b);
-+}
-+
-+
-+/* Returns: -1 if a == b; 0 if a != b */
-+static inline u8 const_time_eq_u8(unsigned int a, unsigned int b)
-+{
-+ return (u8) const_time_eq(a, b);
-+}
-+
-+
-+/**
-+ * const_time_eq_bin - Constant time memory comparison
-+ * @a: First buffer to compare
-+ * @b: Second buffer to compare
-+ * @len: Number of octets to compare
-+ * Returns: -1 if buffers are equal, 0 if not
-+ *
-+ * This function is meant for comparing passwords or hash values where
-+ * difference in execution time or memory access pattern could provide external
-+ * observer information about the location of the difference in the memory
-+ * buffers. The return value does not behave like memcmp(), i.e.,
-+ * const_time_eq_bin() cannot be used to sort items into a defined order. Unlike
-+ * memcmp(), the execution time of const_time_eq_bin() does not depend on the
-+ * contents of the compared memory buffers, but only on the total compared
-+ * length.
-+ */
-+static inline unsigned int const_time_eq_bin(const void *a, const void *b,
-+ size_t len)
-+{
-+ const u8 *aa = a;
-+ const u8 *bb = b;
-+ size_t i;
-+ u8 res = 0;
-+
-+ for (i = 0; i < len; i++)
-+ res |= aa[i] ^ bb[i];
-+
-+ return const_time_is_zero(res);
-+}
-+
-+
-+/**
-+ * const_time_select - Constant time unsigned int selection
-+ * @mask: 0 (false) or -1 (true) to identify which value to select
-+ * @true_val: Value to select for the true case
-+ * @false_val: Value to select for the false case
-+ * Returns: true_val if mask == -1, false_val if mask == 0
-+ */
-+static inline unsigned int const_time_select(unsigned int mask,
-+ unsigned int true_val,
-+ unsigned int false_val)
-+{
-+ return (mask & true_val) | (~mask & false_val);
-+}
-+
-+
-+/**
-+ * const_time_select_int - Constant time int selection
-+ * @mask: 0 (false) or -1 (true) to identify which value to select
-+ * @true_val: Value to select for the true case
-+ * @false_val: Value to select for the false case
-+ * Returns: true_val if mask == -1, false_val if mask == 0
-+ */
-+static inline int const_time_select_int(unsigned int mask, int true_val,
-+ int false_val)
-+{
-+ return (int) const_time_select(mask, (unsigned int) true_val,
-+ (unsigned int) false_val);
-+}
-+
-+
-+/**
-+ * const_time_select_u8 - Constant time u8 selection
-+ * @mask: 0 (false) or -1 (true) to identify which value to select
-+ * @true_val: Value to select for the true case
-+ * @false_val: Value to select for the false case
-+ * Returns: true_val if mask == -1, false_val if mask == 0
-+ */
-+static inline u8 const_time_select_u8(u8 mask, u8 true_val, u8 false_val)
-+{
-+ return (u8) const_time_select(mask, true_val, false_val);
-+}
-+
-+
-+/**
-+ * const_time_select_s8 - Constant time s8 selection
-+ * @mask: 0 (false) or -1 (true) to identify which value to select
-+ * @true_val: Value to select for the true case
-+ * @false_val: Value to select for the false case
-+ * Returns: true_val if mask == -1, false_val if mask == 0
-+ */
-+static inline s8 const_time_select_s8(u8 mask, s8 true_val, s8 false_val)
-+{
-+ return (s8) const_time_select(mask, (unsigned int) true_val,
-+ (unsigned int) false_val);
-+}
-+
-+
-+/**
-+ * const_time_select_bin - Constant time binary buffer selection copy
-+ * @mask: 0 (false) or -1 (true) to identify which value to copy
-+ * @true_val: Buffer to copy for the true case
-+ * @false_val: Buffer to copy for the false case
-+ * @len: Number of octets to copy
-+ * @dst: Destination buffer for the copy
-+ *
-+ * This function copies the specified buffer into the destination buffer using
-+ * operations with identical memory access pattern regardless of which buffer
-+ * is being copied.
-+ */
-+static inline void const_time_select_bin(u8 mask, const u8 *true_val,
-+ const u8 *false_val, size_t len,
-+ u8 *dst)
-+{
-+ size_t i;
-+
-+ for (i = 0; i < len; i++)
-+ dst[i] = const_time_select_u8(mask, true_val[i], false_val[i]);
-+}
-+
-+
-+static inline int const_time_memcmp(const void *a, const void *b, size_t len)
-+{
-+ const u8 *aa = a;
-+ const u8 *bb = b;
-+ int diff, res = 0;
-+ unsigned int mask;
-+
-+ if (len == 0)
-+ return 0;
-+ do {
-+ len--;
-+ diff = (int) aa[len] - (int) bb[len];
-+ mask = const_time_is_zero((unsigned int) diff);
-+ res = const_time_select_int(mask, res, diff);
-+ } while (len);
-+
-+ return res;
-+}
-+
-+#endif /* CONST_TIME_H */
projects / openwrt / staging / ynezz.git / blobdiff