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Merged PR 10593466: Clean up GHash assertions and SAL annotations bas…
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…ed on feedback

Another follow up to !10578579, this PR removes unnecessary assertions and SAL annotations from `GHashAppendData*` to be more consistent with other SymCrypt functions. It turns out that passing in data that aren't a multiple of the block size can sometimes be convenient because it allows one to make calls to the function unconditional. I added a comment at the function definition to indicate that data beyond multiples of the block size are ignored.

Tested: local unit tests (AMD64 noasm), CI pipelines
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@mlindgren
mlindgren committed Apr 12, 2024
1 parent 60abd9e commit 171f697
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Showing 3 changed files with 31 additions and 29 deletions.
18 changes: 9 additions & 9 deletions lib/gcm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -351,16 +351,16 @@ SymCryptGcmSetNonce(
// If len(nonce) != 96 bits (12 bytes),
// pre-counter block = GHASH(nonce padded to a multiple of 128 bits || (QWORD) len(nonce))
BYTE buf[SYMCRYPT_GF128_BLOCK_SIZE];
SIZE_T cbNonceRemainder = cbNonce & 0xf;
if(cbNonce >= SYMCRYPT_GF128_BLOCK_SIZE)
{
SymCryptGHashAppendData( &pState->pKey->ghashKey, &pState->ghashState, pbNonce,
cbNonce - cbNonceRemainder );
}
SIZE_T cbNonceRemainder = cbNonce & (SYMCRYPT_GF128_BLOCK_SIZE - 1);

// Process all full blocks of the nonce, i.e. all nonce bytes up to a multiple of
// SYMCRYPT_GF128_BLOCK_SIZE. SymCryptGHashAppendData ignores additional data that are
// not a multiple of the block size. We will handle any such remaining data below.
// (This also works if the nonce is less than the block size.)
SymCryptGHashAppendData( &pState->pKey->ghashKey, &pState->ghashState, pbNonce, cbNonce );

// If the nonce length is not a multiple of 128 bits, it needs to be padded with zeros
// until it is, as GHASH is only defined on multiples of 128 bits.
// If the nonce length is not a multiple of SYMCRYPT_GF128_BLOCK_SIZE, we need to pad any
// remaining data to a multiple of the block size.
if(cbNonceRemainder > 0)
{
SymCryptWipeKnownSize( buf, sizeof(buf) );
Expand Down
27 changes: 12 additions & 15 deletions lib/ghash.c
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Original file line number Diff line number Diff line change
Expand Up @@ -59,14 +59,11 @@ SymCryptGHashExpandKeyC(
VOID
SYMCRYPT_CALL
SymCryptGHashAppendDataC(
_In_reads_( SYMCRYPT_GF128_FIELD_SIZE ) PCSYMCRYPT_GF128_ELEMENT expandedKeyTable,
_Inout_ PSYMCRYPT_GF128_ELEMENT pState,
_In_reads_( cbData ) PCBYTE pbData,
_In_range_( SYMCRYPT_GF128_BLOCK_SIZE, SIZE_T_MAX & ~0xf) SIZE_T cbData )
_In_reads_( SYMCRYPT_GF128_FIELD_SIZE ) PCSYMCRYPT_GF128_ELEMENT expandedKeyTable,
_Inout_ PSYMCRYPT_GF128_ELEMENT pState,
_In_reads_( cbData ) PCBYTE pbData,
SIZE_T cbData )
{
SYMCRYPT_ASSERT(cbData >= SYMCRYPT_GF128_BLOCK_SIZE);
SYMCRYPT_ASSERT((cbData & 0xf) == 0);

UINT64 R0, R1;
UINT64 mask;
SYMCRYPT_ALIGN UINT32 state32[4];
Expand Down Expand Up @@ -145,7 +142,7 @@ SymCryptGHashAppendDataXmm(
_In_reads_( SYMCRYPT_GF128_FIELD_SIZE ) PCSYMCRYPT_GF128_ELEMENT expandedKeyTable,
_Inout_ PSYMCRYPT_GF128_ELEMENT pState,
_In_reads_( cbData ) PCBYTE pbData,
_In_ SIZE_T cbData )
SIZE_T cbData )
{
__m128i R;
__m128i cmpValue;
Expand Down Expand Up @@ -244,7 +241,7 @@ SymCryptGHashAppendDataNeon(
_In_reads_( SYMCRYPT_GF128_FIELD_SIZE ) PCSYMCRYPT_GF128_ELEMENT expandedKeyTable,
_Inout_ PSYMCRYPT_GF128_ELEMENT pState,
_In_reads_( cbData ) PCBYTE pbData,
_In_ SIZE_T cbData )
SIZE_T cbData )
{
// Room for improvement: replace non-crypto NEON code below, based on a bit by bit lookup with
// pmull on 8b elements - 8x(8bx8b) -> 8x(16b) pmull is NEON instruction since Armv7
Expand Down Expand Up @@ -576,7 +573,7 @@ SymCryptGHashAppendDataPclmulqdq(
_In_reads_( SYMCRYPT_GF128_FIELD_SIZE ) PCSYMCRYPT_GF128_ELEMENT expandedKeyTable,
_Inout_ PSYMCRYPT_GF128_ELEMENT pState,
_In_reads_( cbData ) PCBYTE pbData,
_In_ SIZE_T cbData )
SIZE_T cbData )
{
__m128i state;
__m128i data;
Expand Down Expand Up @@ -710,7 +707,7 @@ SymCryptGHashAppendDataPmull(
_In_reads_( SYMCRYPT_GF128_FIELD_SIZE ) PCSYMCRYPT_GF128_ELEMENT expandedKeyTable,
_Inout_ PSYMCRYPT_GF128_ELEMENT pState,
_In_reads_( cbData ) PCBYTE pbData,
_In_ SIZE_T cbData )
SIZE_T cbData )
{
__n128 state;
__n128 data, datax;
Expand Down Expand Up @@ -844,10 +841,10 @@ SymCryptGHashExpandKey(
VOID
SYMCRYPT_CALL
SymCryptGHashAppendData(
_In_ PCSYMCRYPT_GHASH_EXPANDED_KEY expandedKey,
_Inout_ PSYMCRYPT_GF128_ELEMENT pState,
_In_reads_( cbData ) PCBYTE pbData,
_In_ SIZE_T cbData )
_In_ PCSYMCRYPT_GHASH_EXPANDED_KEY expandedKey,
_Inout_ PSYMCRYPT_GF128_ELEMENT pState,
_In_reads_( cbData ) PCBYTE pbData,
SIZE_T cbData )
{
#if SYMCRYPT_CPU_X86
PCSYMCRYPT_GF128_ELEMENT pExpandedKeyTable;
Expand Down
15 changes: 10 additions & 5 deletions lib/sc_lib.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -933,45 +933,50 @@ SymCryptGHashExpandKeyAmd64(
_Out_writes_( SYMCRYPT_GF128_FIELD_SIZE ) PSYMCRYPT_GF128_ELEMENT expandedKey,
_In_reads_( SYMCRYPT_GF128_BLOCK_SIZE ) PCBYTE pH );

//
// For all GHashAppendData functions, data will be appended in multiples of SYMCRYPT_GF128_BLOCK_SIZE.
// If the data is not a multiple of SYMCRYPT_GF128_BLOCK_SIZE, any remaining data will be ignored.
//

VOID
SYMCRYPT_CALL
SymCryptGHashAppendData(
_In_ PCSYMCRYPT_GHASH_EXPANDED_KEY expandedKey,
_Inout_ PSYMCRYPT_GF128_ELEMENT pState,
_In_reads_( cbData ) PCBYTE pbData,
_In_ SIZE_T cbData );
SIZE_T cbData );

VOID
SYMCRYPT_CALL
SymCryptGHashAppendDataC(
_In_reads_( SYMCRYPT_GF128_FIELD_SIZE ) PCSYMCRYPT_GF128_ELEMENT expandedKeyTable,
_Inout_ PSYMCRYPT_GF128_ELEMENT pState,
_In_reads_( cbData ) PCBYTE pbData,
_In_ SIZE_T cbData );
SIZE_T cbData );

VOID
SYMCRYPT_CALL
SymCryptGHashAppendDataXmm(
_In_reads_( SYMCRYPT_GF128_FIELD_SIZE ) PCSYMCRYPT_GF128_ELEMENT expandedKeyTable,
_Inout_ PSYMCRYPT_GF128_ELEMENT pState,
_In_reads_( cbData ) PCBYTE pbData,
_In_ SIZE_T cbData );
SIZE_T cbData );

VOID
SYMCRYPT_CALL
SymCryptGHashAppendDataNeon(
_In_reads_( SYMCRYPT_GF128_FIELD_SIZE ) PCSYMCRYPT_GF128_ELEMENT expandedKeyTable,
_Inout_ PSYMCRYPT_GF128_ELEMENT pState,
_In_reads_( cbData ) PCBYTE pbData,
_In_ SIZE_T cbData );
SIZE_T cbData );

VOID
SYMCRYPT_CALL
SymCryptGHashAppendDataPclmulqdq(
_In_reads_( SYMCRYPT_GF128_FIELD_SIZE ) PCSYMCRYPT_GF128_ELEMENT expandedKeyTable,
_Inout_ PSYMCRYPT_GF128_ELEMENT pState,
_In_reads_( cbData ) PCBYTE pbData,
_In_ SIZE_T cbData );
SIZE_T cbData );

VOID
SYMCRYPT_CALL
Expand Down

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