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-rw-r--r--main/hostapd/0008-Add-helper-functions-for-constant-time-operations.patch218
1 files changed, 218 insertions, 0 deletions
diff --git a/main/hostapd/0008-Add-helper-functions-for-constant-time-operations.patch b/main/hostapd/0008-Add-helper-functions-for-constant-time-operations.patch
new file mode 100644
index 0000000000..e0b8550c8f
--- /dev/null
+++ b/main/hostapd/0008-Add-helper-functions-for-constant-time-operations.patch
@@ -0,0 +1,218 @@
+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] 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
+
+diff --git a/src/utils/const_time.h b/src/utils/const_time.h
+new file mode 100644
+index 000000000..ab8f611ef
+--- /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 */
+--
+2.21.0
+