diff options
Diffstat (limited to 'block')
| -rw-r--r-- | block/keyslot-manager.c | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/block/keyslot-manager.c b/block/keyslot-manager.c index ac7ce83a76e8..9f9494b80148 100644 --- a/block/keyslot-manager.c +++ b/block/keyslot-manager.c @@ -425,6 +425,113 @@ void blk_ksm_unregister(struct request_queue *q) } /** + * blk_ksm_intersect_modes() - restrict supported modes by child device + * @parent: The keyslot manager for parent device + * @child: The keyslot manager for child device, or NULL + * + * Clear any crypto mode support bits in @parent that aren't set in @child. + * If @child is NULL, then all parent bits are cleared. + * + * Only use this when setting up the keyslot manager for a layered device, + * before it's been exposed yet. + */ +void blk_ksm_intersect_modes(struct blk_keyslot_manager *parent, + const struct blk_keyslot_manager *child) +{ + if (child) { + unsigned int i; + + parent->max_dun_bytes_supported = + min(parent->max_dun_bytes_supported, + child->max_dun_bytes_supported); + for (i = 0; i < ARRAY_SIZE(child->crypto_modes_supported); + i++) { + parent->crypto_modes_supported[i] &= + child->crypto_modes_supported[i]; + } + } else { + parent->max_dun_bytes_supported = 0; + memset(parent->crypto_modes_supported, 0, + sizeof(parent->crypto_modes_supported)); + } +} +EXPORT_SYMBOL_GPL(blk_ksm_intersect_modes); + +/** + * blk_ksm_is_superset() - Check if a KSM supports a superset of crypto modes + * and DUN bytes that another KSM supports. Here, + * "superset" refers to the mathematical meaning of the + * word - i.e. if two KSMs have the *same* capabilities, + * they *are* considered supersets of each other. + * @ksm_superset: The KSM that we want to verify is a superset + * @ksm_subset: The KSM that we want to verify is a subset + * + * Return: True if @ksm_superset supports a superset of the crypto modes and DUN + * bytes that @ksm_subset supports. + */ +bool blk_ksm_is_superset(struct blk_keyslot_manager *ksm_superset, + struct blk_keyslot_manager *ksm_subset) +{ + int i; + + if (!ksm_subset) + return true; + + if (!ksm_superset) + return false; + + for (i = 0; i < ARRAY_SIZE(ksm_superset->crypto_modes_supported); i++) { + if (ksm_subset->crypto_modes_supported[i] & + (~ksm_superset->crypto_modes_supported[i])) { + return false; + } + } + + if (ksm_subset->max_dun_bytes_supported > + ksm_superset->max_dun_bytes_supported) { + return false; + } + + return true; +} +EXPORT_SYMBOL_GPL(blk_ksm_is_superset); + +/** + * blk_ksm_update_capabilities() - Update the restrictions of a KSM to those of + * another KSM + * @target_ksm: The KSM whose restrictions to update. + * @reference_ksm: The KSM to whose restrictions this function will update + * @target_ksm's restrictions to. + * + * Blk-crypto requires that crypto capabilities that were + * advertised when a bio was created continue to be supported by the + * device until that bio is ended. This is turn means that a device cannot + * shrink its advertised crypto capabilities without any explicit + * synchronization with upper layers. So if there's no such explicit + * synchronization, @reference_ksm must support all the crypto capabilities that + * @target_ksm does + * (i.e. we need blk_ksm_is_superset(@reference_ksm, @target_ksm) == true). + * + * Note also that as long as the crypto capabilities are being expanded, the + * order of updates becoming visible is not important because it's alright + * for blk-crypto to see stale values - they only cause blk-crypto to + * believe that a crypto capability isn't supported when it actually is (which + * might result in blk-crypto-fallback being used if available, or the bio being + * failed). + */ +void blk_ksm_update_capabilities(struct blk_keyslot_manager *target_ksm, + struct blk_keyslot_manager *reference_ksm) +{ + memcpy(target_ksm->crypto_modes_supported, + reference_ksm->crypto_modes_supported, + sizeof(target_ksm->crypto_modes_supported)); + + target_ksm->max_dun_bytes_supported = + reference_ksm->max_dun_bytes_supported; +} +EXPORT_SYMBOL_GPL(blk_ksm_update_capabilities); + +/** * blk_ksm_init_passthrough() - Init a passthrough keyslot manager * @ksm: The keyslot manager to init * |