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1// SPDX-License-Identifier: GPL-2.02/*3 * Copyright 2019 Google LLC4 */5 6/*7 * Refer to Documentation/block/inline-encryption.rst for detailed explanation.8 */9 10#define pr_fmt(fmt) "blk-crypto: " fmt11 12#include <linux/bio.h>13#include <linux/blkdev.h>14#include <linux/blk-crypto-profile.h>15#include <linux/module.h>16#include <linux/ratelimit.h>17#include <linux/slab.h>18 19#include "blk-crypto-internal.h"20 21const struct blk_crypto_mode blk_crypto_modes[] = {22 [BLK_ENCRYPTION_MODE_AES_256_XTS] = {23 .name = "AES-256-XTS",24 .cipher_str = "xts(aes)",25 .keysize = 64,26 .ivsize = 16,27 },28 [BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV] = {29 .name = "AES-128-CBC-ESSIV",30 .cipher_str = "essiv(cbc(aes),sha256)",31 .keysize = 16,32 .ivsize = 16,33 },34 [BLK_ENCRYPTION_MODE_ADIANTUM] = {35 .name = "Adiantum",36 .cipher_str = "adiantum(xchacha12,aes)",37 .keysize = 32,38 .ivsize = 32,39 },40 [BLK_ENCRYPTION_MODE_SM4_XTS] = {41 .name = "SM4-XTS",42 .cipher_str = "xts(sm4)",43 .keysize = 32,44 .ivsize = 16,45 },46};47 48/*49 * This number needs to be at least (the number of threads doing IO50 * concurrently) * (maximum recursive depth of a bio), so that we don't51 * deadlock on crypt_ctx allocations. The default is chosen to be the same52 * as the default number of post read contexts in both EXT4 and F2FS.53 */54static int num_prealloc_crypt_ctxs = 128;55 56module_param(num_prealloc_crypt_ctxs, int, 0444);57MODULE_PARM_DESC(num_prealloc_crypt_ctxs,58 "Number of bio crypto contexts to preallocate");59 60static struct kmem_cache *bio_crypt_ctx_cache;61static mempool_t *bio_crypt_ctx_pool;62 63static int __init bio_crypt_ctx_init(void)64{65 size_t i;66 67 bio_crypt_ctx_cache = KMEM_CACHE(bio_crypt_ctx, 0);68 if (!bio_crypt_ctx_cache)69 goto out_no_mem;70 71 bio_crypt_ctx_pool = mempool_create_slab_pool(num_prealloc_crypt_ctxs,72 bio_crypt_ctx_cache);73 if (!bio_crypt_ctx_pool)74 goto out_no_mem;75 76 /* This is assumed in various places. */77 BUILD_BUG_ON(BLK_ENCRYPTION_MODE_INVALID != 0);78 79 /* Sanity check that no algorithm exceeds the defined limits. */80 for (i = 0; i < BLK_ENCRYPTION_MODE_MAX; i++) {81 BUG_ON(blk_crypto_modes[i].keysize > BLK_CRYPTO_MAX_KEY_SIZE);82 BUG_ON(blk_crypto_modes[i].ivsize > BLK_CRYPTO_MAX_IV_SIZE);83 }84 85 return 0;86out_no_mem:87 panic("Failed to allocate mem for bio crypt ctxs\n");88}89subsys_initcall(bio_crypt_ctx_init);90 91void bio_crypt_set_ctx(struct bio *bio, const struct blk_crypto_key *key,92 const u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE], gfp_t gfp_mask)93{94 struct bio_crypt_ctx *bc;95 96 /*97 * The caller must use a gfp_mask that contains __GFP_DIRECT_RECLAIM so98 * that the mempool_alloc() can't fail.99 */100 WARN_ON_ONCE(!(gfp_mask & __GFP_DIRECT_RECLAIM));101 102 bc = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);103 104 bc->bc_key = key;105 memcpy(bc->bc_dun, dun, sizeof(bc->bc_dun));106 107 bio->bi_crypt_context = bc;108}109 110void __bio_crypt_free_ctx(struct bio *bio)111{112 mempool_free(bio->bi_crypt_context, bio_crypt_ctx_pool);113 bio->bi_crypt_context = NULL;114}115 116int __bio_crypt_clone(struct bio *dst, struct bio *src, gfp_t gfp_mask)117{118 dst->bi_crypt_context = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);119 if (!dst->bi_crypt_context)120 return -ENOMEM;121 *dst->bi_crypt_context = *src->bi_crypt_context;122 return 0;123}124 125/* Increments @dun by @inc, treating @dun as a multi-limb integer. */126void bio_crypt_dun_increment(u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE],127 unsigned int inc)128{129 int i;130 131 for (i = 0; inc && i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) {132 dun[i] += inc;133 /*134 * If the addition in this limb overflowed, then we need to135 * carry 1 into the next limb. Else the carry is 0.136 */137 if (dun[i] < inc)138 inc = 1;139 else140 inc = 0;141 }142}143 144void __bio_crypt_advance(struct bio *bio, unsigned int bytes)145{146 struct bio_crypt_ctx *bc = bio->bi_crypt_context;147 148 bio_crypt_dun_increment(bc->bc_dun,149 bytes >> bc->bc_key->data_unit_size_bits);150}151 152/*153 * Returns true if @bc->bc_dun plus @bytes converted to data units is equal to154 * @next_dun, treating the DUNs as multi-limb integers.155 */156bool bio_crypt_dun_is_contiguous(const struct bio_crypt_ctx *bc,157 unsigned int bytes,158 const u64 next_dun[BLK_CRYPTO_DUN_ARRAY_SIZE])159{160 int i;161 unsigned int carry = bytes >> bc->bc_key->data_unit_size_bits;162 163 for (i = 0; i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) {164 if (bc->bc_dun[i] + carry != next_dun[i])165 return false;166 /*167 * If the addition in this limb overflowed, then we need to168 * carry 1 into the next limb. Else the carry is 0.169 */170 if ((bc->bc_dun[i] + carry) < carry)171 carry = 1;172 else173 carry = 0;174 }175 176 /* If the DUN wrapped through 0, don't treat it as contiguous. */177 return carry == 0;178}179 180/*181 * Checks that two bio crypt contexts are compatible - i.e. that182 * they are mergeable except for data_unit_num continuity.183 */184static bool bio_crypt_ctx_compatible(struct bio_crypt_ctx *bc1,185 struct bio_crypt_ctx *bc2)186{187 if (!bc1)188 return !bc2;189 190 return bc2 && bc1->bc_key == bc2->bc_key;191}192 193bool bio_crypt_rq_ctx_compatible(struct request *rq, struct bio *bio)194{195 return bio_crypt_ctx_compatible(rq->crypt_ctx, bio->bi_crypt_context);196}197 198/*199 * Checks that two bio crypt contexts are compatible, and also200 * that their data_unit_nums are continuous (and can hence be merged)201 * in the order @bc1 followed by @bc2.202 */203bool bio_crypt_ctx_mergeable(struct bio_crypt_ctx *bc1, unsigned int bc1_bytes,204 struct bio_crypt_ctx *bc2)205{206 if (!bio_crypt_ctx_compatible(bc1, bc2))207 return false;208 209 return !bc1 || bio_crypt_dun_is_contiguous(bc1, bc1_bytes, bc2->bc_dun);210}211 212/* Check that all I/O segments are data unit aligned. */213static bool bio_crypt_check_alignment(struct bio *bio)214{215 const unsigned int data_unit_size =216 bio->bi_crypt_context->bc_key->crypto_cfg.data_unit_size;217 struct bvec_iter iter;218 struct bio_vec bv;219 220 bio_for_each_segment(bv, bio, iter) {221 if (!IS_ALIGNED(bv.bv_len | bv.bv_offset, data_unit_size))222 return false;223 }224 225 return true;226}227 228blk_status_t __blk_crypto_rq_get_keyslot(struct request *rq)229{230 return blk_crypto_get_keyslot(rq->q->crypto_profile,231 rq->crypt_ctx->bc_key,232 &rq->crypt_keyslot);233}234 235void __blk_crypto_rq_put_keyslot(struct request *rq)236{237 blk_crypto_put_keyslot(rq->crypt_keyslot);238 rq->crypt_keyslot = NULL;239}240 241void __blk_crypto_free_request(struct request *rq)242{243 /* The keyslot, if one was needed, should have been released earlier. */244 if (WARN_ON_ONCE(rq->crypt_keyslot))245 __blk_crypto_rq_put_keyslot(rq);246 247 mempool_free(rq->crypt_ctx, bio_crypt_ctx_pool);248 rq->crypt_ctx = NULL;249}250 251/**252 * __blk_crypto_bio_prep - Prepare bio for inline encryption253 *254 * @bio_ptr: pointer to original bio pointer255 *256 * If the bio crypt context provided for the bio is supported by the underlying257 * device's inline encryption hardware, do nothing.258 *259 * Otherwise, try to perform en/decryption for this bio by falling back to the260 * kernel crypto API. When the crypto API fallback is used for encryption,261 * blk-crypto may choose to split the bio into 2 - the first one that will262 * continue to be processed and the second one that will be resubmitted via263 * submit_bio_noacct. A bounce bio will be allocated to encrypt the contents264 * of the aforementioned "first one", and *bio_ptr will be updated to this265 * bounce bio.266 *267 * Caller must ensure bio has bio_crypt_ctx.268 *269 * Return: true on success; false on error (and bio->bi_status will be set270 * appropriately, and bio_endio() will have been called so bio271 * submission should abort).272 */273bool __blk_crypto_bio_prep(struct bio **bio_ptr)274{275 struct bio *bio = *bio_ptr;276 const struct blk_crypto_key *bc_key = bio->bi_crypt_context->bc_key;277 278 /* Error if bio has no data. */279 if (WARN_ON_ONCE(!bio_has_data(bio))) {280 bio->bi_status = BLK_STS_IOERR;281 goto fail;282 }283 284 if (!bio_crypt_check_alignment(bio)) {285 bio->bi_status = BLK_STS_IOERR;286 goto fail;287 }288 289 /*290 * Success if device supports the encryption context, or if we succeeded291 * in falling back to the crypto API.292 */293 if (blk_crypto_config_supported_natively(bio->bi_bdev,294 &bc_key->crypto_cfg))295 return true;296 if (blk_crypto_fallback_bio_prep(bio_ptr))297 return true;298fail:299 bio_endio(*bio_ptr);300 return false;301}302 303int __blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio,304 gfp_t gfp_mask)305{306 if (!rq->crypt_ctx) {307 rq->crypt_ctx = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);308 if (!rq->crypt_ctx)309 return -ENOMEM;310 }311 *rq->crypt_ctx = *bio->bi_crypt_context;312 return 0;313}314 315/**316 * blk_crypto_init_key() - Prepare a key for use with blk-crypto317 * @blk_key: Pointer to the blk_crypto_key to initialize.318 * @raw_key: Pointer to the raw key. Must be the correct length for the chosen319 * @crypto_mode; see blk_crypto_modes[].320 * @crypto_mode: identifier for the encryption algorithm to use321 * @dun_bytes: number of bytes that will be used to specify the DUN when this322 * key is used323 * @data_unit_size: the data unit size to use for en/decryption324 *325 * Return: 0 on success, -errno on failure. The caller is responsible for326 * zeroizing both blk_key and raw_key when done with them.327 */328int blk_crypto_init_key(struct blk_crypto_key *blk_key, const u8 *raw_key,329 enum blk_crypto_mode_num crypto_mode,330 unsigned int dun_bytes,331 unsigned int data_unit_size)332{333 const struct blk_crypto_mode *mode;334 335 memset(blk_key, 0, sizeof(*blk_key));336 337 if (crypto_mode >= ARRAY_SIZE(blk_crypto_modes))338 return -EINVAL;339 340 mode = &blk_crypto_modes[crypto_mode];341 if (mode->keysize == 0)342 return -EINVAL;343 344 if (dun_bytes == 0 || dun_bytes > mode->ivsize)345 return -EINVAL;346 347 if (!is_power_of_2(data_unit_size))348 return -EINVAL;349 350 blk_key->crypto_cfg.crypto_mode = crypto_mode;351 blk_key->crypto_cfg.dun_bytes = dun_bytes;352 blk_key->crypto_cfg.data_unit_size = data_unit_size;353 blk_key->data_unit_size_bits = ilog2(data_unit_size);354 blk_key->size = mode->keysize;355 memcpy(blk_key->raw, raw_key, mode->keysize);356 357 return 0;358}359 360bool blk_crypto_config_supported_natively(struct block_device *bdev,361 const struct blk_crypto_config *cfg)362{363 return __blk_crypto_cfg_supported(bdev_get_queue(bdev)->crypto_profile,364 cfg);365}366 367/*368 * Check if bios with @cfg can be en/decrypted by blk-crypto (i.e. either the369 * block_device it's submitted to supports inline crypto, or the370 * blk-crypto-fallback is enabled and supports the cfg).371 */372bool blk_crypto_config_supported(struct block_device *bdev,373 const struct blk_crypto_config *cfg)374{375 return IS_ENABLED(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK) ||376 blk_crypto_config_supported_natively(bdev, cfg);377}378 379/**380 * blk_crypto_start_using_key() - Start using a blk_crypto_key on a device381 * @bdev: block device to operate on382 * @key: A key to use on the device383 *384 * Upper layers must call this function to ensure that either the hardware385 * supports the key's crypto settings, or the crypto API fallback has transforms386 * for the needed mode allocated and ready to go. This function may allocate387 * an skcipher, and *should not* be called from the data path, since that might388 * cause a deadlock389 *390 * Return: 0 on success; -ENOPKG if the hardware doesn't support the key and391 * blk-crypto-fallback is either disabled or the needed algorithm392 * is disabled in the crypto API; or another -errno code.393 */394int blk_crypto_start_using_key(struct block_device *bdev,395 const struct blk_crypto_key *key)396{397 if (blk_crypto_config_supported_natively(bdev, &key->crypto_cfg))398 return 0;399 return blk_crypto_fallback_start_using_mode(key->crypto_cfg.crypto_mode);400}401 402/**403 * blk_crypto_evict_key() - Evict a blk_crypto_key from a block_device404 * @bdev: a block_device on which I/O using the key may have been done405 * @key: the key to evict406 *407 * For a given block_device, this function removes the given blk_crypto_key from408 * the keyslot management structures and evicts it from any underlying hardware409 * keyslot(s) or blk-crypto-fallback keyslot it may have been programmed into.410 *411 * Upper layers must call this before freeing the blk_crypto_key. It must be412 * called for every block_device the key may have been used on. The key must no413 * longer be in use by any I/O when this function is called.414 *415 * Context: May sleep.416 */417void blk_crypto_evict_key(struct block_device *bdev,418 const struct blk_crypto_key *key)419{420 struct request_queue *q = bdev_get_queue(bdev);421 int err;422 423 if (blk_crypto_config_supported_natively(bdev, &key->crypto_cfg))424 err = __blk_crypto_evict_key(q->crypto_profile, key);425 else426 err = blk_crypto_fallback_evict_key(key);427 /*428 * An error can only occur here if the key failed to be evicted from a429 * keyslot (due to a hardware or driver issue) or is allegedly still in430 * use by I/O (due to a kernel bug). Even in these cases, the key is431 * still unlinked from the keyslot management structures, and the caller432 * is allowed and expected to free it right away. There's nothing433 * callers can do to handle errors, so just log them and return void.434 */435 if (err)436 pr_warn_ratelimited("%pg: error %d evicting key\n", bdev, err);437}438EXPORT_SYMBOL_GPL(blk_crypto_evict_key);439