From 3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 2 Sep 2026 15:31:14 -0700 Subject: treewide: refresh kmalloc_obj() conversions This is another run of the Coccinelle script for converting kmalloc() family of allocations to kmalloc_obj() via the existing rules in scripts/coccinelle/api/kmalloc_objs.cocci This catches both the set of kmalloc() uses added since the first kmalloc_obj() conversions in v7.0 and adds a large group missed in the first pass due to Coccinelle not interacting well with the cleanup.h scoped_...() family of macros[1]. I worked around this with spatch's "--macro-file" argument to a file with all the scoped_...() macros mapped to Coccinelle's YACFE_ITERATOR[2] as that was the closest viable control flow indicator I could find. Build tested allmodconfig on x86, arm64, arm, loongarch, mips, powerpc, riscv, and s390 with no new warnings. Link: https://lore.kernel.org/lkml/202609021314.8A9C0B8@keescook/ [1] Link: https://github.com/coccinelle/coccinelle/blob/master/standard.h [2] Signed-off-by: Kees Cook --- block/blk-crypto-fallback.c | 676 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 676 insertions(+) create mode 100644 block/blk-crypto-fallback.c (limited to 'block/blk-crypto-fallback.c') diff --git a/block/blk-crypto-fallback.c b/block/blk-crypto-fallback.c new file mode 100644 index 000000000..2a8f40a65 --- /dev/null +++ b/block/blk-crypto-fallback.c @@ -0,0 +1,676 @@ +// 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-fallback: " fmt + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "blk-cgroup.h" +#include "blk-crypto-internal.h" + +static unsigned int num_prealloc_bounce_pg = BIO_MAX_VECS; +module_param(num_prealloc_bounce_pg, uint, 0); +MODULE_PARM_DESC(num_prealloc_bounce_pg, + "Number of preallocated bounce pages for the blk-crypto crypto API fallback"); + +static unsigned int blk_crypto_num_keyslots = 100; +module_param_named(num_keyslots, blk_crypto_num_keyslots, uint, 0); +MODULE_PARM_DESC(num_keyslots, + "Number of keyslots for the blk-crypto crypto API fallback"); + +static unsigned int num_prealloc_fallback_crypt_ctxs = 128; +module_param(num_prealloc_fallback_crypt_ctxs, uint, 0); +MODULE_PARM_DESC(num_prealloc_crypt_fallback_ctxs, + "Number of preallocated bio fallback crypto contexts for blk-crypto to use during crypto API fallback"); + +struct bio_fallback_crypt_ctx { + struct bio_crypt_ctx crypt_ctx; + /* + * Copy of the bvec_iter when this bio was submitted. + * We only want to en/decrypt the part of the bio as described by the + * bvec_iter upon submission because bio might be split before being + * resubmitted + */ + struct bvec_iter crypt_iter; + union { + struct { + struct work_struct work; + struct bio *bio; + }; + struct { + void *bi_private_orig; + bio_end_io_t *bi_end_io_orig; + }; + }; +}; + +static struct kmem_cache *bio_fallback_crypt_ctx_cache; +static mempool_t *bio_fallback_crypt_ctx_pool; + +/* + * Allocating a crypto tfm during I/O can deadlock, so we have to preallocate + * all of a mode's tfms when that mode starts being used. Since each mode may + * need all the keyslots at some point, each mode needs its own tfm for each + * keyslot; thus, a keyslot may contain tfms for multiple modes. However, to + * match the behavior of real inline encryption hardware (which only supports a + * single encryption context per keyslot), we only allow one tfm per keyslot to + * be used at a time - the rest of the unused tfms have their keys cleared. + */ +static DEFINE_MUTEX(tfms_init_lock); +static bool tfms_inited[BLK_ENCRYPTION_MODE_MAX]; + +static struct blk_crypto_fallback_keyslot { + enum blk_crypto_mode_num crypto_mode; + struct crypto_sync_skcipher *tfms[BLK_ENCRYPTION_MODE_MAX]; +} *blk_crypto_keyslots; + +static struct blk_crypto_profile *blk_crypto_fallback_profile; +static struct workqueue_struct *blk_crypto_wq; +static mempool_t *blk_crypto_bounce_page_pool; +static struct bio_set enc_bio_set; + +/* + * This is the key we set when evicting a keyslot. This *should* be the all 0's + * key, but AES-XTS rejects that key, so we use some random bytes instead. + */ +static u8 blank_key[BLK_CRYPTO_MAX_RAW_KEY_SIZE]; + +static void blk_crypto_fallback_evict_keyslot(unsigned int slot) +{ + struct blk_crypto_fallback_keyslot *slotp = &blk_crypto_keyslots[slot]; + enum blk_crypto_mode_num crypto_mode = slotp->crypto_mode; + int err; + + WARN_ON(slotp->crypto_mode == BLK_ENCRYPTION_MODE_INVALID); + + /* Clear the key in the skcipher */ + err = crypto_sync_skcipher_setkey(slotp->tfms[crypto_mode], blank_key, + blk_crypto_modes[crypto_mode].keysize); + WARN_ON(err); + slotp->crypto_mode = BLK_ENCRYPTION_MODE_INVALID; +} + +static int +blk_crypto_fallback_keyslot_program(struct blk_crypto_profile *profile, + const struct blk_crypto_key *key, + unsigned int slot) +{ + struct blk_crypto_fallback_keyslot *slotp = &blk_crypto_keyslots[slot]; + const enum blk_crypto_mode_num crypto_mode = + key->crypto_cfg.crypto_mode; + int err; + + if (crypto_mode != slotp->crypto_mode && + slotp->crypto_mode != BLK_ENCRYPTION_MODE_INVALID) + blk_crypto_fallback_evict_keyslot(slot); + + slotp->crypto_mode = crypto_mode; + err = crypto_sync_skcipher_setkey(slotp->tfms[crypto_mode], key->bytes, + key->size); + if (err) { + blk_crypto_fallback_evict_keyslot(slot); + return err; + } + return 0; +} + +static int blk_crypto_fallback_keyslot_evict(struct blk_crypto_profile *profile, + const struct blk_crypto_key *key, + unsigned int slot) +{ + blk_crypto_fallback_evict_keyslot(slot); + return 0; +} + +static const struct blk_crypto_ll_ops blk_crypto_fallback_ll_ops = { + .keyslot_program = blk_crypto_fallback_keyslot_program, + .keyslot_evict = blk_crypto_fallback_keyslot_evict, +}; + +static void blk_crypto_fallback_encrypt_endio(struct bio *enc_bio) +{ + struct bio *src_bio = enc_bio->bi_private; + struct page **pages = (struct page **)enc_bio->bi_io_vec; + struct bio_vec *bv; + unsigned int i; + + /* + * Use the same trick as the alloc side to avoid the need for an extra + * pages array. + */ + bio_for_each_bvec_all(bv, enc_bio, i) + pages[i] = bv->bv_page; + + i = mempool_free_bulk(blk_crypto_bounce_page_pool, (void **)pages, + enc_bio->bi_vcnt); + if (i < enc_bio->bi_vcnt) + release_pages(pages + i, enc_bio->bi_vcnt - i); + + if (enc_bio->bi_status) + cmpxchg(&src_bio->bi_status, 0, enc_bio->bi_status); + + bio_put(enc_bio); + bio_endio(src_bio); +} + +#define PAGE_PTRS_PER_BVEC (sizeof(struct bio_vec) / sizeof(struct page *)) + +static struct bio *blk_crypto_alloc_enc_bio(struct bio *bio_src, + unsigned int nr_segs, struct page ***pages_ret) +{ + unsigned int memflags = memalloc_noio_save(); + unsigned int nr_allocated; + struct page **pages; + struct bio *bio; + + bio = bio_alloc_bioset(bio_src->bi_bdev, nr_segs, bio_src->bi_opf, + GFP_NOIO, &enc_bio_set); + if (bio_flagged(bio_src, BIO_REMAPPED)) + bio_set_flag(bio, BIO_REMAPPED); + bio->bi_private = bio_src; + bio->bi_end_io = blk_crypto_fallback_encrypt_endio; + bio->bi_ioprio = bio_src->bi_ioprio; + bio->bi_write_hint = bio_src->bi_write_hint; + bio->bi_write_stream = bio_src->bi_write_stream; + bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector; + bio_clone_blkg_association(bio, bio_src); + + /* + * Move page array up in the allocated memory for the bio vecs as far as + * possible so that we can start filling biovecs from the beginning + * without overwriting the temporary page array. + */ + static_assert(PAGE_PTRS_PER_BVEC > 1); + pages = (struct page **)bio->bi_io_vec; + pages += nr_segs * (PAGE_PTRS_PER_BVEC - 1); + + /* + * Try a bulk allocation first. This might not fill all allocated + * pages, but we'll fix that up later in mempool_alloc_bulk. + * + * Note: alloc_pages_bulk needs the array to be zeroed, as it assumes + * any non-zero slot already contains a valid allocation. + */ + memset(pages, 0, sizeof(struct page *) * nr_segs); + nr_allocated = alloc_pages_bulk(GFP_KERNEL, nr_segs, pages); + if (nr_allocated < nr_segs) + mempool_alloc_bulk(blk_crypto_bounce_page_pool, + (void **)pages + nr_allocated, + nr_segs - nr_allocated); + memalloc_noio_restore(memflags); + *pages_ret = pages; + return bio; +} + +static struct crypto_sync_skcipher * +blk_crypto_fallback_tfm(struct blk_crypto_keyslot *slot) +{ + const struct blk_crypto_fallback_keyslot *slotp = + &blk_crypto_keyslots[blk_crypto_keyslot_index(slot)]; + + return slotp->tfms[slotp->crypto_mode]; +} + +union blk_crypto_iv { + __le64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE]; + u8 bytes[BLK_CRYPTO_MAX_IV_SIZE]; +}; + +static void blk_crypto_dun_to_iv(const u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE], + union blk_crypto_iv *iv) +{ + int i; + + for (i = 0; i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) + iv->dun[i] = cpu_to_le64(dun[i]); +} + +static void __blk_crypto_fallback_encrypt_bio(struct bio *src_bio, + struct crypto_sync_skcipher *tfm) +{ + struct bio_crypt_ctx *bc = src_bio->bi_crypt_context; + int data_unit_size = bc->bc_key->crypto_cfg.data_unit_size; + SYNC_SKCIPHER_REQUEST_ON_STACK(ciph_req, tfm); + u64 curr_dun[BLK_CRYPTO_DUN_ARRAY_SIZE]; + struct scatterlist src, dst; + union blk_crypto_iv iv; + unsigned int nr_enc_pages, enc_idx; + struct page **enc_pages; + struct bio *enc_bio; + unsigned int i; + + skcipher_request_set_callback(ciph_req, + CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, + NULL, NULL); + + memcpy(curr_dun, bc->bc_dun, sizeof(curr_dun)); + sg_init_table(&src, 1); + sg_init_table(&dst, 1); + + skcipher_request_set_crypt(ciph_req, &src, &dst, data_unit_size, + iv.bytes); + + /* + * Encrypt each page in the source bio. Because the source bio could + * have bio_vecs that span more than a single page, but the encrypted + * bios are limited to a single page per bio_vec, this can generate + * more than a single encrypted bio per source bio. + */ +new_bio: + nr_enc_pages = min(bio_segments(src_bio), BIO_MAX_VECS); + enc_bio = blk_crypto_alloc_enc_bio(src_bio, nr_enc_pages, &enc_pages); + enc_idx = 0; + for (;;) { + struct bio_vec src_bv = + bio_iter_iovec(src_bio, src_bio->bi_iter); + struct page *enc_page = enc_pages[enc_idx]; + + if (!IS_ALIGNED(src_bv.bv_len | src_bv.bv_offset, + data_unit_size)) { + enc_bio->bi_status = BLK_STS_INVAL; + goto out_free_enc_bio; + } + + __bio_add_page(enc_bio, enc_page, src_bv.bv_len, + src_bv.bv_offset); + + sg_set_page(&src, src_bv.bv_page, data_unit_size, + src_bv.bv_offset); + sg_set_page(&dst, enc_page, data_unit_size, src_bv.bv_offset); + + /* + * Increment the index now that the encrypted page is added to + * the bio. This is important for the error unwind path. + */ + enc_idx++; + + /* + * Encrypt each data unit in this page. + */ + for (i = 0; i < src_bv.bv_len; i += data_unit_size) { + blk_crypto_dun_to_iv(curr_dun, &iv); + if (crypto_skcipher_encrypt(ciph_req)) { + enc_bio->bi_status = BLK_STS_IOERR; + goto out_free_enc_bio; + } + bio_crypt_dun_increment(curr_dun, 1); + src.offset += data_unit_size; + dst.offset += data_unit_size; + } + + bio_advance_iter_single(src_bio, &src_bio->bi_iter, + src_bv.bv_len); + if (!src_bio->bi_iter.bi_size) + break; + + if (enc_idx == nr_enc_pages) { + /* + * For each additional encrypted bio submitted, + * increment the source bio's remaining count. Each + * encrypted bio's completion handler calls bio_endio on + * the source bio, so this keeps the source bio from + * completing until the last encrypted bio does. + */ + bio_inc_remaining(src_bio); + submit_bio(enc_bio); + goto new_bio; + } + } + + submit_bio(enc_bio); + return; + +out_free_enc_bio: + /* + * Add the remaining pages to the bio so that the normal completion path + * in blk_crypto_fallback_encrypt_endio frees them. The exact data + * layout does not matter for that, so don't bother iterating the source + * bio. + */ + for (; enc_idx < nr_enc_pages; enc_idx++) + __bio_add_page(enc_bio, enc_pages[enc_idx], PAGE_SIZE, 0); + bio_endio(enc_bio); +} + +/* + * The crypto API fallback's encryption routine. + * + * Allocate one or more bios for encryption, encrypt the input bio using the + * crypto API, and submit the encrypted bios. Sets bio->bi_status and + * completes the source bio on error + */ +static void blk_crypto_fallback_encrypt_bio(struct bio *src_bio) +{ + struct bio_crypt_ctx *bc = src_bio->bi_crypt_context; + struct blk_crypto_keyslot *slot; + blk_status_t status; + + status = blk_crypto_get_keyslot(blk_crypto_fallback_profile, + bc->bc_key, &slot); + if (status != BLK_STS_OK) { + bio_endio_status(src_bio, status); + return; + } + __blk_crypto_fallback_encrypt_bio(src_bio, + blk_crypto_fallback_tfm(slot)); + blk_crypto_put_keyslot(slot); +} + +static blk_status_t __blk_crypto_fallback_decrypt_bio(struct bio *bio, + struct bio_crypt_ctx *bc, struct bvec_iter iter, + struct crypto_sync_skcipher *tfm) +{ + SYNC_SKCIPHER_REQUEST_ON_STACK(ciph_req, tfm); + u64 curr_dun[BLK_CRYPTO_DUN_ARRAY_SIZE]; + union blk_crypto_iv iv; + struct scatterlist sg; + struct bio_vec bv; + const int data_unit_size = bc->bc_key->crypto_cfg.data_unit_size; + unsigned int i; + + skcipher_request_set_callback(ciph_req, + CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, + NULL, NULL); + + memcpy(curr_dun, bc->bc_dun, sizeof(curr_dun)); + sg_init_table(&sg, 1); + skcipher_request_set_crypt(ciph_req, &sg, &sg, data_unit_size, + iv.bytes); + + /* Decrypt each segment in the bio */ + __bio_for_each_segment(bv, bio, iter, iter) { + struct page *page = bv.bv_page; + + if (!IS_ALIGNED(bv.bv_len | bv.bv_offset, data_unit_size)) + return BLK_STS_INVAL; + + sg_set_page(&sg, page, data_unit_size, bv.bv_offset); + + /* Decrypt each data unit in the segment */ + for (i = 0; i < bv.bv_len; i += data_unit_size) { + blk_crypto_dun_to_iv(curr_dun, &iv); + if (crypto_skcipher_decrypt(ciph_req)) + return BLK_STS_IOERR; + bio_crypt_dun_increment(curr_dun, 1); + sg.offset += data_unit_size; + } + } + + return BLK_STS_OK; +} + +/* + * The crypto API fallback's main decryption routine. + * + * Decrypts input bio in place, and calls bio_endio on the bio. + */ +static void blk_crypto_fallback_decrypt_bio(struct work_struct *work) +{ + struct bio_fallback_crypt_ctx *f_ctx = + container_of(work, struct bio_fallback_crypt_ctx, work); + struct bio *bio = f_ctx->bio; + struct bio_crypt_ctx *bc = &f_ctx->crypt_ctx; + struct blk_crypto_keyslot *slot; + blk_status_t status; + + status = blk_crypto_get_keyslot(blk_crypto_fallback_profile, + bc->bc_key, &slot); + if (status == BLK_STS_OK) { + status = __blk_crypto_fallback_decrypt_bio(bio, bc, + f_ctx->crypt_iter, + blk_crypto_fallback_tfm(slot)); + blk_crypto_put_keyslot(slot); + } + mempool_free(f_ctx, bio_fallback_crypt_ctx_pool); + + bio_endio_status(bio, status); +} + +/** + * blk_crypto_fallback_decrypt_endio - queue bio for fallback decryption + * + * @bio: the bio to queue + * + * Restore bi_private and bi_end_io, and queue the bio for decryption into a + * workqueue, since this function will be called from an atomic context. + */ +static void blk_crypto_fallback_decrypt_endio(struct bio *bio) +{ + struct bio_fallback_crypt_ctx *f_ctx = bio->bi_private; + + bio->bi_private = f_ctx->bi_private_orig; + bio->bi_end_io = f_ctx->bi_end_io_orig; + + /* If there was an IO error, don't queue for decrypt. */ + if (bio->bi_status) { + mempool_free(f_ctx, bio_fallback_crypt_ctx_pool); + bio_endio(bio); + return; + } + + INIT_WORK(&f_ctx->work, blk_crypto_fallback_decrypt_bio); + f_ctx->bio = bio; + queue_work(blk_crypto_wq, &f_ctx->work); +} + +/** + * blk_crypto_fallback_bio_prep - Prepare a bio to use fallback en/decryption + * @bio: bio to prepare + * + * If bio is doing a WRITE operation, allocate one or more bios to contain the + * encrypted payload and submit them. + * + * For a READ operation, mark the bio for decryption by using bi_private and + * bi_end_io. + * + * In either case, this function will make the submitted bio(s) look like + * regular bios (i.e. as if no encryption context was ever specified) for the + * purposes of the rest of the stack except for blk-integrity (blk-integrity and + * blk-crypto are not currently supported together). + * + * Return: true if @bio should be submitted to the driver by the caller, else + * false. Sets bio->bi_status, calls bio_endio and returns false on error. + */ +bool blk_crypto_fallback_bio_prep(struct bio *bio) +{ + struct bio_crypt_ctx *bc = bio->bi_crypt_context; + struct bio_fallback_crypt_ctx *f_ctx; + + if (WARN_ON_ONCE(!tfms_inited[bc->bc_key->crypto_cfg.crypto_mode])) { + /* User didn't call blk_crypto_start_using_key() first */ + bio_io_error(bio); + return false; + } + + if (bc->bc_key->crypto_cfg.key_type != BLK_CRYPTO_KEY_TYPE_RAW) { + bio_endio_status(bio, BLK_STS_NOTSUPP); + return false; + } + + if (bio_data_dir(bio) == WRITE) { + blk_crypto_fallback_encrypt_bio(bio); + return false; + } + + /* + * bio READ case: Set up a f_ctx in the bio's bi_private and set the + * bi_end_io appropriately to trigger decryption when the bio is ended. + */ + f_ctx = mempool_alloc(bio_fallback_crypt_ctx_pool, GFP_NOIO); + f_ctx->crypt_ctx = *bc; + f_ctx->crypt_iter = bio->bi_iter; + f_ctx->bi_private_orig = bio->bi_private; + f_ctx->bi_end_io_orig = bio->bi_end_io; + bio->bi_private = (void *)f_ctx; + bio->bi_end_io = blk_crypto_fallback_decrypt_endio; + bio_crypt_free_ctx(bio); + + return true; +} + +int blk_crypto_fallback_evict_key(const struct blk_crypto_key *key) +{ + return __blk_crypto_evict_key(blk_crypto_fallback_profile, key); +} + +static bool blk_crypto_fallback_inited; +static int blk_crypto_fallback_init(void) +{ + int i; + int err; + + if (blk_crypto_fallback_inited) + return 0; + + get_random_bytes(blank_key, sizeof(blank_key)); + + err = bioset_init(&enc_bio_set, 64, 0, BIOSET_NEED_BVECS); + if (err) + goto out; + + /* Dynamic allocation is needed because of lockdep_register_key(). */ + blk_crypto_fallback_profile = kzalloc_obj(*blk_crypto_fallback_profile); + if (!blk_crypto_fallback_profile) { + err = -ENOMEM; + goto fail_free_bioset; + } + + err = blk_crypto_profile_init(blk_crypto_fallback_profile, + blk_crypto_num_keyslots); + if (err) + goto fail_free_profile; + err = -ENOMEM; + + blk_crypto_fallback_profile->ll_ops = blk_crypto_fallback_ll_ops; + blk_crypto_fallback_profile->max_dun_bytes_supported = BLK_CRYPTO_MAX_IV_SIZE; + blk_crypto_fallback_profile->key_types_supported = BLK_CRYPTO_KEY_TYPE_RAW; + + /* All blk-crypto modes have a crypto API fallback. */ + for (i = 0; i < BLK_ENCRYPTION_MODE_MAX; i++) + blk_crypto_fallback_profile->modes_supported[i] = 0xFFFFFFFF; + blk_crypto_fallback_profile->modes_supported[BLK_ENCRYPTION_MODE_INVALID] = 0; + + blk_crypto_wq = alloc_workqueue("blk_crypto_wq", + WQ_UNBOUND | WQ_HIGHPRI | + WQ_MEM_RECLAIM, num_online_cpus()); + if (!blk_crypto_wq) + goto fail_destroy_profile; + + blk_crypto_keyslots = kzalloc_objs(blk_crypto_keyslots[0], + blk_crypto_num_keyslots); + if (!blk_crypto_keyslots) + goto fail_free_wq; + + blk_crypto_bounce_page_pool = + mempool_create_page_pool(num_prealloc_bounce_pg, 0); + if (!blk_crypto_bounce_page_pool) + goto fail_free_keyslots; + + bio_fallback_crypt_ctx_cache = KMEM_CACHE(bio_fallback_crypt_ctx, 0); + if (!bio_fallback_crypt_ctx_cache) + goto fail_free_bounce_page_pool; + + bio_fallback_crypt_ctx_pool = + mempool_create_slab_pool(num_prealloc_fallback_crypt_ctxs, + bio_fallback_crypt_ctx_cache); + if (!bio_fallback_crypt_ctx_pool) + goto fail_free_crypt_ctx_cache; + + blk_crypto_fallback_inited = true; + + return 0; +fail_free_crypt_ctx_cache: + kmem_cache_destroy(bio_fallback_crypt_ctx_cache); +fail_free_bounce_page_pool: + mempool_destroy(blk_crypto_bounce_page_pool); +fail_free_keyslots: + kfree(blk_crypto_keyslots); +fail_free_wq: + destroy_workqueue(blk_crypto_wq); +fail_destroy_profile: + blk_crypto_profile_destroy(blk_crypto_fallback_profile); +fail_free_profile: + kfree(blk_crypto_fallback_profile); +fail_free_bioset: + bioset_exit(&enc_bio_set); +out: + return err; +} + +/* + * Prepare blk-crypto-fallback for the specified crypto mode. + * Returns -ENOPKG if the needed crypto API support is missing. + */ +int blk_crypto_fallback_start_using_mode(enum blk_crypto_mode_num mode_num) +{ + const char *cipher_str = blk_crypto_modes[mode_num].cipher_str; + struct blk_crypto_fallback_keyslot *slotp; + unsigned int i; + int err = 0; + + /* + * Fast path + * Ensure that updates to blk_crypto_keyslots[i].tfms[mode_num] + * for each i are visible before we try to access them. + */ + if (likely(smp_load_acquire(&tfms_inited[mode_num]))) + return 0; + + mutex_lock(&tfms_init_lock); + if (tfms_inited[mode_num]) + goto out; + + err = blk_crypto_fallback_init(); + if (err) + goto out; + + for (i = 0; i < blk_crypto_num_keyslots; i++) { + slotp = &blk_crypto_keyslots[i]; + slotp->tfms[mode_num] = crypto_alloc_sync_skcipher(cipher_str, + 0, 0); + if (IS_ERR(slotp->tfms[mode_num])) { + err = PTR_ERR(slotp->tfms[mode_num]); + if (err == -ENOENT) { + pr_warn_once("Missing crypto API support for \"%s\"\n", + cipher_str); + err = -ENOPKG; + } + slotp->tfms[mode_num] = NULL; + goto out_free_tfms; + } + + crypto_sync_skcipher_set_flags(slotp->tfms[mode_num], + CRYPTO_TFM_REQ_FORBID_WEAK_KEYS); + } + + /* + * Ensure that updates to blk_crypto_keyslots[i].tfms[mode_num] + * for each i are visible before we set tfms_inited[mode_num]. + */ + smp_store_release(&tfms_inited[mode_num], true); + goto out; + +out_free_tfms: + for (i = 0; i < blk_crypto_num_keyslots; i++) { + slotp = &blk_crypto_keyslots[i]; + crypto_free_sync_skcipher(slotp->tfms[mode_num]); + slotp->tfms[mode_num] = NULL; + } +out: + mutex_unlock(&tfms_init_lock); + return err; +} -- cgit v1.3.1