On 5/6/19 3:35 PM, Satya Tangirala wrote:
> +#ifdef CONFIG_BLK_CRYPT_CTX
> +static inline void bio_crypt_advance(struct bio *bio, unsigned int bytes)
> +{
> + if (bio_is_encrypted(bio)) {
> + bio->bi_crypt_context.data_unit_num +=
> + bytes >> bio->bi_crypt_context.data_unit_size_bits;
> + }
> +}
> +
> +void bio_clone_crypt_context(struct bio *dst, struct bio *src)
> +{
> + if (bio_crypt_swhandled(src))
> + return;
> + dst->bi_crypt_context = src->bi_crypt_context;
> +
> + if (!bio_crypt_has_keyslot(src))
> + return;
> +
> + /**
Please use "/*" to start comment blocks other than kernel-doc headers.
> + * This should always succeed because the src bio should already
> + * have a reference to the keyslot.
> + */
> + BUG_ON(!keyslot_manager_get_slot(src->bi_crypt_context.processing_ksm,
> + src->bi_crypt_context.keyslot));
Are you aware that using BUG_ON() if there is a reasonable way to
recover is not acceptable?
> +}
> +
> +bool bio_crypt_should_process(struct bio *bio, struct request_queue *q)
> +{
> + if (!bio_is_encrypted(bio))
> + return false;
> +
> + WARN_ON(!bio_crypt_has_keyslot(bio));
> + return q->ksm == bio->bi_crypt_context.processing_ksm;
> +}
> +EXPORT_SYMBOL(bio_crypt_should_process);
> +
> +#endif /* CONFIG_BLK_CRYPT_CTX */
Please move these new functions into a separate source file instead of
using #ifdef / #endif. I think the coding style documentation mentions
this explicitly.
> +static struct blk_crypto_keyslot {
> + struct crypto_skcipher *tfm;
> + int crypto_alg_id;
> + union {
> + u8 key[BLK_CRYPTO_MAX_KEY_SIZE];
> + u32 key_words[BLK_CRYPTO_MAX_KEY_SIZE/4];
> + };
> +} *slot_mem;
What is the purpose of the key_words[] member? Is it used anywhere? If
not, can it be left out?
> diff --git a/block/blk-merge.c b/block/blk-merge.c
> index 1c9d4f0f96ea..55133c547bdf 100644
> --- a/block/blk-merge.c
> +++ b/block/blk-merge.c
> @@ -614,6 +614,59 @@ int blk_rq_map_sg(struct request_queue *q, struct request *rq,
> }
> EXPORT_SYMBOL(blk_rq_map_sg);
>
> +#ifdef CONFIG_BLK_CRYPT_CTX
> +/*
> + * Checks that two bio crypt contexts are compatible - i.e. that
> + * they are mergeable except for data_unit_num continuity.
> + */
> +static inline bool bio_crypt_ctx_compatible(struct bio *b_1, struct bio *b_2)
> +{
> + struct bio_crypt_ctx *bc1 = &b_1->bi_crypt_context;
> + struct bio_crypt_ctx *bc2 = &b_2->bi_crypt_context;
> +
> + if (bio_is_encrypted(b_1) != bio_is_encrypted(b_2) ||
> + bc1->keyslot != bc2->keyslot)
> + return false;
> +
> + return !bio_is_encrypted(b_1) ||
> + bc1->data_unit_size_bits == bc2->data_unit_size_bits;
> +}
> +
> +/*
> + * Checks that two bio crypt contexts are compatible, and also
> + * that their data_unit_nums are continuous (and can hence be merged)
> + */
> +static inline bool bio_crypt_ctx_back_mergeable(struct bio *b_1,
> + unsigned int b1_sectors,
> + struct bio *b_2)
> +{
> + struct bio_crypt_ctx *bc1 = &b_1->bi_crypt_context;
> + struct bio_crypt_ctx *bc2 = &b_2->bi_crypt_context;
> +
> + if (!bio_crypt_ctx_compatible(b_1, b_2))
> + return false;
> +
> + return !bio_is_encrypted(b_1) ||
> + (bc1->data_unit_num +
> + (b1_sectors >> (bc1->data_unit_size_bits - 9)) ==
> + bc2->data_unit_num);
> +}
> +
> +#else /* CONFIG_BLK_CRYPT_CTX */
> +static inline bool bio_crypt_ctx_compatible(struct bio *b_1, struct bio *b_2)
> +{
> + return true;
> +}
> +
> +static inline bool bio_crypt_ctx_back_mergeable(struct bio *b_1,
> + unsigned int b1_sectors,
> + struct bio *b_2)
> +{
> + return true;
> +}
> +
> +#endif /* CONFIG_BLK_CRYPT_CTX */
Can the above functions be moved into a new file such that the
#ifdef/#endif construct can be avoided?
> + /* Wait till there is a free slot available */
> + while (atomic_read(&ksm->num_idle_slots) == 0) {
> + mutex_unlock(&ksm->lock);
> + wait_event(ksm->wait_queue,
> + (atomic_read(&ksm->num_idle_slots) > 0));
> + mutex_lock(&ksm->lock);
> + }
Using an atomic_read() inside code protected by a mutex is suspicious.
Would protecting all ksm->num_idle_slots manipulations with ksm->lock
and making ksm->num_idle_slots a regular integer have a negative
performance impact?
> +struct keyslot_mgmt_ll_ops {
> + int (*keyslot_program)(void *ll_priv_data, const u8 *key,
> + unsigned int data_unit_size,
> + /* crypto_alg_id returned by crypto_alg_find */
> + unsigned int crypto_alg_id,
> + unsigned int slot);
> + /**
> + * Evict key from all keyslots in the keyslot manager.
> + * The key, data_unit_size and crypto_alg_id are also passed down
> + * so that for e.g. dm layers that have their own keyslot
> + * managers can evict keys from the devices that they map over.
> + * Returns 0 on success, -errno otherwise.
> + */
> + int (*keyslot_evict)(void *ll_priv_data, unsigned int slot,
> + const u8 *key, unsigned int data_unit_size,
> + unsigned int crypto_alg_id);
> + /**
> + * Get a crypto_alg_id (used internally by the lower layer driver) that
> + * represents the given blk-crypto crypt_mode and data_unit_size. The
> + * returned crypto_alg_id will be used in future calls to the lower
> + * layer driver (in keyslot_program and keyslot_evict) to reference
> + * this crypt_mode, data_unit_size combo. Returns negative error code
> + * if a crypt_mode, data_unit_size combo is not supported.
> + */
> + int (*crypto_alg_find)(void *ll_priv_data,
> + enum blk_crypt_mode_index crypt_mode,
> + unsigned int data_unit_size);
> + /**
> + * Returns the slot number that matches the key,
> + * or -ENOKEY if no match found, or negative on error
> + */
> + int (*keyslot_find)(void *ll_priv_data, const u8 *key,
> + unsigned int data_unit_size,
> + unsigned int crypto_alg_id);
> +};
Have you considered to use kernel-doc format for documenting the members
of the keyslot_mgmt_ll_ops structure?
Thanks,
Bart.
