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luks: Split out crypt reading into its own function

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In preparation for adding support for a new algorithm, move the
decryption part of blkmap_crypt_read() into its own function.

Co-developed-by: Claude <noreply@anthropic.com>
Signed-off-by: Simon Glass <simon.glass@canonical.com>
This commit is contained in:
Simon Glass
2025-11-12 04:36:33 -07:00
parent 3393e4d6ce
commit ed94d01b71
1 changed files with 42 additions and 25 deletions
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67
drivers/block/blkmap_crypt.c
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@@ -45,37 +45,17 @@ struct blkmap_crypt {
u8 essiv_key[32];
};
static ulong blkmap_crypt_read(struct blkmap *bm, struct blkmap_slice *bms,
lbaint_t blknr, lbaint_t blkcnt, void *buffer)
static ulong crypt_read_cbc(struct blkmap *bm, struct blkmap_crypt *bmc,
lbaint_t blknr, lbaint_t blkcnt,
u8 *encrypted_buf, void *buffer)
{
struct blkmap_crypt *bmc = container_of(bms, struct blkmap_crypt, slice);
struct blk_desc *bd = dev_get_uclass_plat(bm->blk);
struct blk_desc *src_bd = dev_get_uclass_plat(bmc->blk);
lbaint_t src_blknr, blocks_read;
u8 *encrypted_buf, *dest = buffer;
u8 expkey[AES256_EXPAND_KEY_LENGTH];
u8 iv[AES_BLOCK_LENGTH];
u8 *dest = buffer;
u64 sector;
lbaint_t i;
/* Allocate buffer for encrypted data */
encrypted_buf = malloc_cache_aligned(blkcnt * src_bd->blksz);
if (!encrypted_buf)
return 0;
/*
* Calculate source block number (LUKS payload offset + requested
* block)
*/
src_blknr = bmc->blknr + bmc->payload_offset + blknr;
/* Read encrypted data from underlying device */
blocks_read = blk_read(bmc->blk, src_blknr, blkcnt, encrypted_buf);
if (blocks_read != blkcnt) {
free(encrypted_buf);
return 0;
}
/* Expand AES key */
aes_expand_key(bmc->master_key, bmc->key_size * 8, expkey);
@@ -116,11 +96,48 @@ static ulong blkmap_crypt_read(struct blkmap *bm, struct blkmap_slice *bms,
dest + i * bd->blksz,
bd->blksz / AES_BLOCK_LENGTH);
}
free(encrypted_buf);
return blkcnt;
}
static ulong blkmap_crypt_read(struct blkmap *bm, struct blkmap_slice *bms,
lbaint_t blknr, lbaint_t blkcnt, void *buffer)
{
struct blkmap_crypt *bmc = container_of(bms, struct blkmap_crypt, slice);
struct blk_desc *src_bd = dev_get_uclass_plat(bmc->blk);
lbaint_t src_blknr, blocks_read;
u8 *encrypted_buf;
ulong result;
/* Allocate buffer for encrypted data */
encrypted_buf = malloc_cache_aligned(blkcnt * src_bd->blksz);
if (!encrypted_buf)
return 0;
/*
* Calculate source block number (LUKS payload offset + requested
* block)
*/
src_blknr = bmc->blknr + bmc->payload_offset + blknr;
/* Read encrypted data from underlying device */
blocks_read = blk_read(bmc->blk, src_blknr, blkcnt, encrypted_buf);
if (blocks_read != blkcnt) {
free(encrypted_buf);
return 0;
}
if (blknr == 0 && blkcnt >= 1) {
log_debug("First 32 bytes of ENCRYPTED data:\n");
log_debug_hex("", encrypted_buf, 32);
}
result = crypt_read_cbc(bm, bmc, blknr, blkcnt, encrypted_buf, buffer);
free(encrypted_buf);
return result;
}
static void blkmap_crypt_destroy(struct blkmap *bm, struct blkmap_slice *bms)
{
struct blkmap_crypt *bmc = container_of(bms, struct blkmap_crypt, slice);