Michael Chang
c90e5054ec
* 0001-lib-crypto-Introduce-new-HMAC-functions-to-reuse-buf.patch * 0002-lib-pbkdf2-Optimize-PBKDF2-by-reusing-HMAC-handle.patch * 0001-kern-misc-Implement-faster-grub_memcpy-for-aligned-b.patch OBS-URL: https://build.opensuse.org/package/show/Base:System/grub2?expand=0&rev=561
60 lines
1.6 KiB
Diff
60 lines
1.6 KiB
Diff
From be4670936bc86a14f20a8c9c40d34c45aad0d0b2 Mon Sep 17 00:00:00 2001
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From: Gary Lin <glin@suse.com>
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Date: Fri, 25 Jul 2025 13:50:23 +0800
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Subject: [PATCH] Constant-time grub_crypto_memcmp()
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Use the constant-time algorithm to compare the given memory blocks.
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The code is extracted from the upstream commit:
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0739d24cd1648531d0708d1079ff6bbfa6140268
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Fix: bsc#1234959
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Signed-off-by: Gary Lin <glin@suse.com>
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---
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grub-core/lib/crypto.c | 23 ++++++++++++++++-------
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1 file changed, 16 insertions(+), 7 deletions(-)
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diff --git a/grub-core/lib/crypto.c b/grub-core/lib/crypto.c
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index 396f764..19db787 100644
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--- a/grub-core/lib/crypto.c
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+++ b/grub-core/lib/crypto.c
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@@ -433,19 +433,28 @@ grub_crypto_gcry_error (gcry_err_code_t in)
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return GRUB_ACCESS_DENIED;
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}
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+/*
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+ * Compare byte arrays of length LEN, return 1 if it's not same,
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+ * 0, otherwise.
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+ */
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int
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-grub_crypto_memcmp (const void *a, const void *b, grub_size_t n)
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+grub_crypto_memcmp (const void *b1, const void *b2, grub_size_t len)
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{
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- register grub_size_t counter = 0;
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- const grub_uint8_t *pa, *pb;
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+ const grub_uint8_t *a = b1;
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+ const grub_uint8_t *b = b2;
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+ int ab, ba;
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+ grub_size_t i;
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- for (pa = a, pb = b; n; pa++, pb++, n--)
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+ /* Constant-time compare. */
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+ for (i = 0, ab = 0, ba = 0; i < len; i++)
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{
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- if (*pa != *pb)
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- counter++;
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+ /* If a[i] != b[i], either ab or ba will be negative. */
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+ ab |= a[i] - b[i];
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+ ba |= b[i] - a[i];
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}
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- return !!counter;
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+ /* 'ab | ba' is negative when buffers are not equal, extract sign bit. */
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+ return ((unsigned int)(ab | ba) >> (sizeof(unsigned int) * 8 - 1)) & 1;
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}
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#ifndef GRUB_UTIL
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--
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2.43.0
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