// SPDX-License-Identifier: GPL-2.0
/*
* Copyright 2019 Google LLC
*/
/*
* Refer to Documentation/block/inline-encryption.rst for detailed explanation.
*/
#define pr_fmt(fmt) "blk-crypto: " fmt
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/keyslot-manager.h>
#include <linux/module.h>
#include <linux/slab.h>
#include "blk-crypto-internal.h"
const struct blk_crypto_mode blk_crypto_modes[] = {
[BLK_ENCRYPTION_MODE_AES_256_XTS] = {
.cipher_str = "xts(aes)",
.keysize = 64,
.ivsize = 16,
},
[BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV] = {
.cipher_str = "essiv(cbc(aes),sha256)",
.keysize = 16,
.ivsize = 16,
},
[BLK_ENCRYPTION_MODE_ADIANTUM] = {
.cipher_str = "adiantum(xchacha12,aes)",
.keysize = 32,
.ivsize = 32,
},
};
/*
* This number needs to be at least (the number of threads doing IO
* concurrently) * (maximum recursive depth of a bio), so that we don't
* deadlock on crypt_ctx allocations. The default is chosen to be the same
* as the default number of post read contexts in both EXT4 and F2FS.
*/
static int num_prealloc_crypt_ctxs = 128;
module_param(num_prealloc_crypt_ctxs, int, 0444);
MODULE_PARM_DESC(num_prealloc_crypt_ctxs,
"Number of bio crypto contexts to preallocate");
static struct kmem_cache *bio_crypt_ctx_cache;
static mempool_t *bio_crypt_ctx_pool;
static int __init bio_crypt_ctx_init(void)
{
size_t i;
bio_crypt_ctx_cache = KMEM_CACHE(bio_crypt_ctx, 0);
if (!bio_crypt_ctx_cache)
goto out_no_mem;
bio_crypt_ctx_pool = mempool_create_slab_pool(num_prealloc_crypt_ctxs,
bio_crypt_ctx_cache);
if (!bio_crypt_ctx_pool)
goto out_no_mem;
/* This is assumed in various places. */
BUILD_BUG_ON(BLK_ENCRYPTION_MODE_INVALID != 0);
/* Sanity check that no algorithm exceeds the defined limits. */
for (i = 0; i < BLK_ENCRYPTION_MODE_MAX; i++) {
BUG_ON(blk_crypto_modes[i].keysize > BLK_CRYPTO_MAX_KEY_SIZE);
BUG_ON(blk_crypto_modes[i].ivsize > BLK_CRYPTO_MAX_IV_SIZE);
}
return 0;
out_no_mem:
panic("Failed to allocate mem for bio crypt ctxs\n");
}
subsys_initcall(bio_crypt_ctx_init);
void bio_crypt_set_ctx(struct bio *bio, const struct blk_crypto_key *key,
const u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE], gfp_t gfp_mask)
{
struct bio_crypt_ctx *bc = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);
bc->bc_key = key;
memcpy(bc->bc_dun, dun, sizeof(bc->bc_dun));
bio->bi_crypt_context = bc;
}
void __bio_crypt_free_ctx(struct bio *bio)
{
mempool_free(bio->bi_crypt_context, bio_crypt_ctx_pool);
bio->bi_crypt_context = NULL;
}
void __bio_crypt_clone(struct bio *dst, struct bio *src, gfp_t gfp_mask)
{
dst->bi_crypt_context = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);
*dst->bi_crypt_context = *src->bi_crypt_context;
}
EXPORT_SYMBOL_GPL(__bio_crypt_clone);
/* Increments @dun by @inc, treating @dun as a multi-limb integer. */
void bio_crypt_dun_increment(u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE],
unsigned int inc)
{
int i;
for (i = 0; inc && i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) {
dun[i] += inc;
/*
* If the addition in this limb overflowed, then we need to
* carry 1 into the next limb. Else the carry is 0.
*/
if (dun[i] < inc)
inc = 1;
else
inc = 0;
}
}
void __bio_crypt_advance(struct bio *bio, unsigned int bytes)
{
struct bio_crypt_ctx *bc = bio->bi_crypt_context;
bio_crypt_dun_increment(bc->bc_dun,
bytes >> bc->bc_key->data_unit_size_bits);
}
/*
* Returns true if @bc->bc_dun plus @bytes converted to data units is equal to
* @next_dun, treating the DUNs as multi-limb integers.
*/
bool bio_crypt_dun_is_contiguous(const struct bio_crypt_ctx *bc,
unsigned int bytes,
const u64 next_dun[BLK_CRYPTO_DUN_ARRAY_SIZE])
{
int i;
unsigned int carry = bytes >> bc->bc_key->data_unit_size_bits;
for (i = 0; i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) {
if (bc->bc_dun[i] + carry != next_dun[i])
return false;
/*
* If the addition in this limb overflowed, then we need to
* carry 1 into the next limb. Else the carry is 0.
*/
if ((bc->bc_dun[i] + carry) < carry)
carry = 1;
else
carry = 0;
}
/* If the DUN wrapped through 0, don't treat it as contiguous. */
return carry == 0;
}
/*
* Checks that two bio crypt contexts are compatible - i.e. that
* they are mergeable except for data_unit_num continuity.
*/
static bool bio_crypt_ctx_compatible(struct bio_crypt_ctx *bc1,
struct bio_crypt_ctx *bc2)
{
if (!bc1)
return !bc2;
return bc2 && bc1->bc_key == bc2->bc_key;
}
bool bio_crypt_rq_ctx_compatible(struct request *rq, struct bio *bio)
{
return bio_crypt_ctx_compatible(rq->crypt_ctx, bio->bi_crypt_context);
}
/*
* Checks that two bio crypt contexts are compatible, and also
* that their data_unit_nums are continuous (and can hence be merged)
* in the order @bc1 followed by @bc2.
*/
bool bio_crypt_ctx_mergeable(struct bio_crypt_ctx *bc1, unsigned int bc1_bytes,
struct bio_crypt_ctx *bc2)
{
if (!bio_crypt_ctx_compatible(bc1, bc2))
return false;
return !bc1 || bio_crypt_dun_is_contiguous(bc1, bc1_bytes, bc2->bc_dun);
}
/* Check that all I/O segments are data unit aligned. */
static bool bio_crypt_check_alignment(struct bio *bio)
{
const unsigned int data_unit_size =
bio->bi_crypt_context->bc_key->crypto_cfg.data_unit_size;
struct bvec_iter iter;
struct bio_vec bv;
bio_for_each_segment(bv, bio, iter) {
if (!IS_ALIGNED(bv.bv_len | bv.bv_offset, data_unit_size))
return false;
}
return true;
}
blk_status_t __blk_crypto_init_request(struct request *rq)
{
return blk_ksm_get_slot_for_key(rq->q->ksm, rq->crypt_ctx->bc_key,
&rq->crypt_keyslot);
}
/**
* __blk_crypto_free_request - Uninitialize the crypto fields of a request.
*
* @rq: The request whose crypto fields to uninitialize.
*
* Completely uninitializes the crypto fields of a request. If a keyslot has
* been programmed into some inline encryption hardware, that keyslot is
* released. The rq->crypt_ctx is also freed.
*/
void __blk_crypto_free_request(struct request *rq)
{
blk_ksm_put_slot(rq->crypt_keyslot);
mempool_free(rq->crypt_ctx, bio_crypt_ctx_pool);
blk_crypto_rq_set_defaults(rq);
}
/**
* __blk_crypto_bio_prep - Prepare bio for inline encryption
*
* @bio_ptr: pointer to original bio pointer
*
* If the bio crypt context provided for the bio is supported by the underlying
* device's inline encryption hardware, do nothing.
*
* Otherwise, try to perform en/decryption for this bio by falling back to the
* kernel crypto API. When the crypto API fallback is used for encryption,
* blk-crypto may choose to split the bio into 2 - the first one that will
* continue to be processed and the second one that will be resubmitted via
* submit_bio_noacct. A bounce bio will be allocated to encrypt the contents
* of the aforementioned "first one", and *bio_ptr will be updated to this
* bounce bio.
*
* Caller must ensure bio has bio_crypt_ctx.
*
* Return: true on success; false on error (and bio->bi_status will be set
* appropriately, and bio_endio() will have been called so bio
* submission should abort).
*/
bool __blk_crypto_bio_prep(struct bio **bio_ptr)
{
struct bio *bio = *bio_ptr;
const struct blk_crypto_key *bc_key = bio->bi_crypt_context->bc_key;
/* Error if bio has no data. */
if (WARN_ON_ONCE(!bio_has_data(bio))) {
bio->bi_status = BLK_STS_IOERR;
goto fail;
}
if (!bio_crypt_check_alignment(bio)) {
bio->bi_status = BLK_STS_IOERR;
goto fail;
}
/*
* Success if device supports the encryption context, or if we succeeded
* in falling back to the crypto API.
*/
if (blk_ksm_crypto_cfg_supported(bio->bi_disk->queue->ksm,
&bc_key->crypto_cfg))
return true;
if (blk_crypto_fallback_bio_prep(bio_ptr))
return true;
fail:
bio_endio(*bio_ptr);
return false;
}
/**
* __blk_crypto_rq_bio_prep - Prepare a request's crypt_ctx when its first bio
* is inserted
*
* @rq: The request to prepare
* @bio: The first bio being inserted into the request
* @gfp_mask: gfp mask
*/
void __blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio,
gfp_t gfp_mask)
{
if (!rq->crypt_ctx)
rq->crypt_ctx = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);
*rq->crypt_ctx = *bio->bi_crypt_context;
}
/**
* blk_crypto_init_key() - Prepare a key for use with blk-crypto
* @blk_key: Pointer to the blk_crypto_key to initialize.
* @raw_key: Pointer to the raw key. Must be the correct length for the chosen
* @crypto_mode; see blk_crypto_modes[].
* @crypto_mode: identifier for the encryption algorithm to use
* @dun_bytes: number of bytes that will be used to specify the DUN when this
* key is used
* @data_unit_size: the data unit size to use for en/decryption
*
* Return: 0 on success, -errno on failure. The caller is responsible for
* zeroizing both blk_key and raw_key when done with them.
*/
int blk_crypto_init_key(struct blk_crypto_key *blk_key, const u8 *raw_key,
enum blk_crypto_mode_num crypto_mode,
unsigned int dun_bytes,
unsigned int data_unit_size)
{
const struct blk_crypto_mode *mode;
memset(blk_key, 0, sizeof(*blk_key));
if (crypto_mode >= ARRAY_SIZE(blk_crypto_modes))
return -EINVAL;
mode = &blk_crypto_modes[crypto_mode];
if (mode->keysize == 0)
return -EINVAL;
if (dun_bytes == 0 || dun_bytes > BLK_CRYPTO_MAX_IV_SIZE)
return -EINVAL;
if (!is_power_of_2(data_unit_size))
return -EINVAL;
blk_key->crypto_cfg.crypto_mode = crypto_mode;
blk_key->crypto_cfg.dun_bytes = dun_bytes;
blk_key->crypto_cfg.data_unit_size = data_unit_size;
blk_key->data_unit_size_bits = ilog2(data_unit_size);
blk_key->size = mode->keysize;
memcpy(blk_key->raw, raw_key, mode->keysize);
return 0;
}
/*
* Check if bios with @cfg can be en/decrypted by blk-crypto (i.e. either the
* request queue it's submitted to supports inline crypto, or the
* blk-crypto-fallback is enabled and supports the cfg).
*/
bool blk_crypto_config_supported(struct request_queue *q,
const struct blk_crypto_config *cfg)
{
return IS_ENABLED(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK) ||
blk_ksm_crypto_cfg_supported(q->ksm, cfg);
}
/**
* blk_crypto_start_using_key() - Start using a blk_crypto_key on a device
* @key: A key to use on the device
* @q: the request queue for the device
*
* Upper layers must call this function to ensure that either the hardware
* supports the key's crypto settings, or the crypto API fallback has transforms
* for the needed mode allocated and ready to go. This function may allocate
* an skcipher, and *should not* be called from the data path, since that might
* cause a deadlock
*
* Return: 0 on success; -ENOPKG if the hardware doesn't support the key and
* blk-crypto-fallback is either disabled or the needed algorithm
* is disabled in the crypto API; or another -errno code.
*/
int blk_crypto_start_using_key(const struct blk_crypto_key *key,
struct request_queue *q)
{
if (blk_ksm_crypto_cfg_supported(q->ksm, &key->crypto_cfg))
return 0;
return blk_crypto_fallback_start_using_mode(key->crypto_cfg.crypto_mode);
}
/**
* blk_crypto_evict_key() - Evict a key from any inline encryption hardware
* it may have been programmed into
* @q: The request queue who's associated inline encryption hardware this key
* might have been programmed into
* @key: The key to evict
*
* Upper layers (filesystems) must call this function to ensure that a key is
* evicted from any hardware that it might have been programmed into. The key
* must not be in use by any in-flight IO when this function is called.
*
* Return: 0 on success or if key is not present in the q's ksm, -err on error.
*/
int blk_crypto_evict_key(struct request_queue *q,
const struct blk_crypto_key *key)
{
if (blk_ksm_crypto_cfg_supported(q->ksm, &key->crypto_cfg))
return blk_ksm_evict_key(q->ksm, key);
/*
* If the request queue's associated inline encryption hardware didn't
* have support for the key, then the key might have been programmed
* into the fallback keyslot manager, so try to evict from there.
*/
return blk_crypto_fallback_evict_key(key);
}
