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-rw-r--r--block/blk-crypto.c422
1 files changed, 422 insertions, 0 deletions
diff --git a/block/blk-crypto.c b/block/blk-crypto.c
new file mode 100644
index 000000000..87ec55d43
--- /dev/null
+++ b/block/blk-crypto.c
@@ -0,0 +1,422 @@
+// 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/ratelimit.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;
+
+ /*
+ * The caller must use a gfp_mask that contains __GFP_DIRECT_RECLAIM so
+ * that the mempool_alloc() can't fail.
+ */
+ WARN_ON_ONCE(!(gfp_mask & __GFP_DIRECT_RECLAIM));
+
+ 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;
+}
+
+int __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);
+ if (!dst->bi_crypt_context)
+ return -ENOMEM;
+ *dst->bi_crypt_context = *src->bi_crypt_context;
+ return 0;
+}
+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_rq_get_keyslot(struct request *rq)
+{
+ return blk_ksm_get_slot_for_key(rq->q->ksm, rq->crypt_ctx->bc_key,
+ &rq->crypt_keyslot);
+}
+
+void __blk_crypto_rq_put_keyslot(struct request *rq)
+{
+ blk_ksm_put_slot(rq->crypt_keyslot);
+ rq->crypt_keyslot = NULL;
+}
+
+void __blk_crypto_free_request(struct request *rq)
+{
+ /* The keyslot, if one was needed, should have been released earlier. */
+ if (WARN_ON_ONCE(rq->crypt_keyslot))
+ __blk_crypto_rq_put_keyslot(rq);
+
+ mempool_free(rq->crypt_ctx, bio_crypt_ctx_pool);
+ rq->crypt_ctx = NULL;
+}
+
+/**
+ * __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;
+}
+
+int __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);
+ if (!rq->crypt_ctx)
+ return -ENOMEM;
+ }
+ *rq->crypt_ctx = *bio->bi_crypt_context;
+ return 0;
+}
+
+/**
+ * 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 > mode->ivsize)
+ 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 blk_crypto_key from a request_queue
+ * @q: a request_queue on which I/O using the key may have been done
+ * @key: the key to evict
+ *
+ * For a given request_queue, this function removes the given blk_crypto_key
+ * from the keyslot management structures and evicts it from any underlying
+ * hardware keyslot(s) or blk-crypto-fallback keyslot it may have been
+ * programmed into.
+ *
+ * Upper layers must call this before freeing the blk_crypto_key. It must be
+ * called for every request_queue the key may have been used on. The key must
+ * no longer be in use by any I/O when this function is called.
+ *
+ * Context: May sleep.
+ */
+void blk_crypto_evict_key(struct request_queue *q,
+ const struct blk_crypto_key *key)
+{
+ int err;
+
+ if (blk_ksm_crypto_cfg_supported(q->ksm, &key->crypto_cfg))
+ err = blk_ksm_evict_key(q->ksm, key);
+ else
+ err = blk_crypto_fallback_evict_key(key);
+ /*
+ * An error can only occur here if the key failed to be evicted from a
+ * keyslot (due to a hardware or driver issue) or is allegedly still in
+ * use by I/O (due to a kernel bug). Even in these cases, the key is
+ * still unlinked from the keyslot management structures, and the caller
+ * is allowed and expected to free it right away. There's nothing
+ * callers can do to handle errors, so just log them and return void.
+ */
+ if (err)
+ pr_warn_ratelimited("error %d evicting key\n", err);
+}