From: Ingo Franzki Date: Fri, 16 Aug 2024 11:21:33 +0000 (+0200) Subject: dm-crypt: Allow to specify the integrity key size as option X-Git-Tag: v6.12-rc1~30^2~17 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4441686b24a1d7acf9834ca95864d67e3f97666a;p=thirdparty%2Fkernel%2Flinux.git dm-crypt: Allow to specify the integrity key size as option For the MAC based integrity operation, the integrity key size (i.e. key_mac_size) is currently set to the digest size of the used digest. For wrapped key HMAC algorithms, the key size is independent of the cryptographic key size. So there is no known size of the mac key in such cases. The desired key size can optionally be specified as argument when the dm-crypt device is configured via 'integrity_key_size:%u'. If no integrity_key_size argument is specified, the mac key size is still set to the digest size, as before. Increase version number to 1.28.0 so that support for the new argument can be detected by user space (i.e. cryptsetup). Signed-off-by: Ingo Franzki Reviewed-by: Milan Broz Signed-off-by: Mikulas Patocka --- diff --git a/Documentation/admin-guide/device-mapper/dm-crypt.rst b/Documentation/admin-guide/device-mapper/dm-crypt.rst index 552c9155165d7..cde1d5594b0d9 100644 --- a/Documentation/admin-guide/device-mapper/dm-crypt.rst +++ b/Documentation/admin-guide/device-mapper/dm-crypt.rst @@ -160,6 +160,10 @@ iv_large_sectors The must be multiple of (in 512 bytes units) if this flag is specified. +integrity_key_size: + Use an integrity key of size instead of using an integrity key size + of the digest size of the used HMAC algorithm. + Module parameters:: diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index 348b4b26c2723..d5533b43054ed 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -147,6 +147,7 @@ enum cipher_flags { CRYPT_MODE_INTEGRITY_AEAD, /* Use authenticated mode for cipher */ CRYPT_IV_LARGE_SECTORS, /* Calculate IV from sector_size, not 512B sectors */ CRYPT_ENCRYPT_PREPROCESS, /* Must preprocess data for encryption (elephant) */ + CRYPT_KEY_MAC_SIZE_SET, /* The integrity_key_size option was used */ }; /* @@ -2937,7 +2938,8 @@ static int crypt_ctr_auth_cipher(struct crypt_config *cc, char *cipher_api) if (IS_ERR(mac)) return PTR_ERR(mac); - cc->key_mac_size = crypto_ahash_digestsize(mac); + if (!test_bit(CRYPT_KEY_MAC_SIZE_SET, &cc->cipher_flags)) + cc->key_mac_size = crypto_ahash_digestsize(mac); crypto_free_ahash(mac); cc->authenc_key = kmalloc(crypt_authenckey_size(cc), GFP_KERNEL); @@ -3219,6 +3221,13 @@ static int crypt_ctr_optional(struct dm_target *ti, unsigned int argc, char **ar cc->cipher_auth = kstrdup(sval, GFP_KERNEL); if (!cc->cipher_auth) return -ENOMEM; + } else if (sscanf(opt_string, "integrity_key_size:%u%c", &val, &dummy) == 1) { + if (!val) { + ti->error = "Invalid integrity_key_size argument"; + return -EINVAL; + } + cc->key_mac_size = val; + set_bit(CRYPT_KEY_MAC_SIZE_SET, &cc->cipher_flags); } else if (sscanf(opt_string, "sector_size:%hu%c", &cc->sector_size, &dummy) == 1) { if (cc->sector_size < (1 << SECTOR_SHIFT) || cc->sector_size > 4096 || @@ -3607,10 +3616,10 @@ static void crypt_status(struct dm_target *ti, status_type_t type, num_feature_args += test_bit(DM_CRYPT_NO_OFFLOAD, &cc->flags); num_feature_args += test_bit(DM_CRYPT_NO_READ_WORKQUEUE, &cc->flags); num_feature_args += test_bit(DM_CRYPT_NO_WRITE_WORKQUEUE, &cc->flags); + num_feature_args += !!cc->used_tag_size; num_feature_args += cc->sector_size != (1 << SECTOR_SHIFT); num_feature_args += test_bit(CRYPT_IV_LARGE_SECTORS, &cc->cipher_flags); - if (cc->used_tag_size) - num_feature_args++; + num_feature_args += test_bit(CRYPT_KEY_MAC_SIZE_SET, &cc->cipher_flags); if (num_feature_args) { DMEMIT(" %d", num_feature_args); if (ti->num_discard_bios) @@ -3631,6 +3640,8 @@ static void crypt_status(struct dm_target *ti, status_type_t type, DMEMIT(" sector_size:%d", cc->sector_size); if (test_bit(CRYPT_IV_LARGE_SECTORS, &cc->cipher_flags)) DMEMIT(" iv_large_sectors"); + if (test_bit(CRYPT_KEY_MAC_SIZE_SET, &cc->cipher_flags)) + DMEMIT(" integrity_key_size:%u", cc->key_mac_size); } break; @@ -3758,7 +3769,7 @@ static void crypt_io_hints(struct dm_target *ti, struct queue_limits *limits) static struct target_type crypt_target = { .name = "crypt", - .version = {1, 27, 0}, + .version = {1, 28, 0}, .module = THIS_MODULE, .ctr = crypt_ctr, .dtr = crypt_dtr,