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[crypto] Ensure relevant GCM cipher state is cleared by cipher_setiv() 

Reset the accumulated authentication state when cipher_setiv() is
called, to allow the cipher to be reused without resetting the key.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
pull/801/head
Michael Brown 2022-11-09 16:45:54 +00:00
parent 7256a6eb24
commit 63577207ab
2 changed files with 17 additions and 11 deletions
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20
src/crypto/gcm.c
View File

@ -452,9 +452,18 @@ int gcm_setkey ( struct gcm_context *context, const void *key, size_t keylen,
* @v ivlen Initialisation vector length
*/
void gcm_setiv ( struct gcm_context *context, const void *iv, size_t ivlen ) {
union gcm_block *check = ( ( void * ) context );
/* Sanity checks */
linker_assert ( &context->hash == check, gcm_bad_layout );
linker_assert ( &context->len == check + 1, gcm_bad_layout );
linker_assert ( &context->ctr == check + 2, gcm_bad_layout );
linker_assert ( &context->key == check + 3, gcm_bad_layout );
/* Reset non-key state */
memset ( context, 0, offsetof ( typeof ( *context ), key ) );
/* Reset counter */
memset ( context->ctr.ctr.iv, 0, sizeof ( context->ctr.ctr.iv ) );
context->ctr.ctr.value = cpu_to_be32 ( 1 );
/* Process initialisation vector */
@ -468,13 +477,10 @@ void gcm_setiv ( struct gcm_context *context, const void *iv, size_t ivlen ) {
/* Calculate hash over initialisation vector */
gcm_process ( context, iv, NULL, iv, ivlen );
gcm_hash ( context, &context->ctr );
/* Reset accumulated hash */
memset ( &context->hash, 0, sizeof ( context->hash ) );
/* Reset data lengths */
assert ( context->len.len.add == 0 );
context->len.len.data = 0;
/* Reset non-key, non-counter state */
memset ( context, 0, offsetof ( typeof ( *context ), ctr ) );
}
DBGC2 ( context, "GCM %p Y[0]:\n", context );

8
src/include/ipxe/gcm.h
View File

@ -44,14 +44,14 @@ union gcm_block {
/** GCM context */
struct gcm_context {
/** Hash key (H) */
union gcm_block key;
/** Counter (Y) */
union gcm_block ctr;
/** Accumulated hash (X) */
union gcm_block hash;
/** Accumulated lengths */
union gcm_block len;
/** Counter (Y) */
union gcm_block ctr;
/** Hash key (H) */
union gcm_block key;
/** Underlying block cipher */
struct cipher_algorithm *raw_cipher;
/** Underlying block cipher context */