[build] Fix build failures with random versions of gcc

For unknown reasons, miscellaneous versions of gcc seem to struggle
with the static assertions used to ensure the correct layout of the
GCM structures.

Adjust the assertions to use offsetof() rather than direct pointer
comparison, on the basis that offsetof() must be a compile-time
constant value.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
pull/1130/merge
Michael Brown 2024-03-27 14:28:47 +00:00
parent 9bbe77669c
commit 37850e0e85
2 changed files with 18 additions and 15 deletions

View File

@ -109,6 +109,9 @@ static union gcm_block gcm_cached_mult[256];
*/ */
static uint16_t gcm_cached_reduce[256]; static uint16_t gcm_cached_reduce[256];
/** Offset of a field within GCM context */
#define gcm_offset( field ) offsetof ( struct gcm_context, field )
/** /**
* Reverse bits in a byte * Reverse bits in a byte
* *
@ -470,17 +473,13 @@ int gcm_setkey ( struct gcm_context *context, const void *key, size_t keylen,
*/ */
void gcm_setiv ( struct gcm_context *context, const void *iv, size_t ivlen ) { void gcm_setiv ( struct gcm_context *context, const void *iv, size_t ivlen ) {
/* Sanity check: ensure that memset()s will clear expected state */
build_assert ( &context->hash < &context->ctr );
build_assert ( &context->len < &context->ctr );
build_assert ( &context->ctr < &context->key );
build_assert ( ( ( void * ) &context->raw_cipher ) >
( ( void * ) &context->key ) );
build_assert ( ( ( void * ) context->raw_ctx ) >
( ( void * ) &context->key ) );
/* Reset non-key state */ /* Reset non-key state */
memset ( context, 0, offsetof ( typeof ( *context ), key ) ); memset ( context, 0, gcm_offset ( key ) );
build_assert ( gcm_offset ( key ) > gcm_offset ( hash ) );
build_assert ( gcm_offset ( key ) > gcm_offset ( len ) );
build_assert ( gcm_offset ( key ) > gcm_offset ( ctr ) );
build_assert ( gcm_offset ( key ) < gcm_offset ( raw_cipher ) );
build_assert ( gcm_offset ( key ) < gcm_offset ( raw_ctx ) );
/* Reset counter */ /* Reset counter */
context->ctr.ctr.value = cpu_to_be32 ( 1 ); context->ctr.ctr.value = cpu_to_be32 ( 1 );
@ -499,7 +498,12 @@ void gcm_setiv ( struct gcm_context *context, const void *iv, size_t ivlen ) {
assert ( context->len.len.add == 0 ); assert ( context->len.len.add == 0 );
/* Reset non-key, non-counter state */ /* Reset non-key, non-counter state */
memset ( context, 0, offsetof ( typeof ( *context ), ctr ) ); memset ( context, 0, gcm_offset ( ctr ) );
build_assert ( gcm_offset ( ctr ) > gcm_offset ( hash ) );
build_assert ( gcm_offset ( ctr ) > gcm_offset ( len ) );
build_assert ( gcm_offset ( ctr ) < gcm_offset ( key ) );
build_assert ( gcm_offset ( ctr ) < gcm_offset ( raw_cipher ) );
build_assert ( gcm_offset ( ctr ) < gcm_offset ( raw_ctx ) );
} }
DBGC2 ( context, "GCM %p Y[0]:\n", context ); DBGC2 ( context, "GCM %p Y[0]:\n", context );

View File

@ -89,10 +89,9 @@ static int _gcm_name ## _setkey ( void *ctx, const void *key, \
size_t keylen ) { \ size_t keylen ) { \
struct _gcm_name ## _context *context = ctx; \ struct _gcm_name ## _context *context = ctx; \
build_assert ( _blocksize == sizeof ( context->gcm.key ) ); \ build_assert ( _blocksize == sizeof ( context->gcm.key ) ); \
build_assert ( ( ( void * ) &context->gcm ) == \ build_assert ( offsetof ( typeof ( *context ), gcm ) == 0 ); \
( ( void * ) context ) ); \ build_assert ( offsetof ( typeof ( *context ), raw ) == \
build_assert ( ( ( void * ) &context->raw ) == \ offsetof ( typeof ( *context ), gcm.raw_ctx ) ); \
( ( void * ) context->gcm.raw_ctx ) ); \
return gcm_setkey ( &context->gcm, key, keylen, &_raw_cipher ); \ return gcm_setkey ( &context->gcm, key, keylen, &_raw_cipher ); \
} \ } \
static void _gcm_name ## _setiv ( void *ctx, const void *iv, \ static void _gcm_name ## _setiv ( void *ctx, const void *iv, \