// SPDX-License-Identifier: GPL-2.0-only /* * aes-ce-glue.c - wrapper code for ARMv8 AES * * Copyright (C) 2015 Linaro Ltd */ #include #include #include #include #include #include #include #include #include #include #include #include MODULE_DESCRIPTION("AES-ECB/CBC/CTR/XTS using ARMv8 Crypto Extensions"); MODULE_AUTHOR("Ard Biesheuvel "); MODULE_LICENSE("GPL v2"); /* defined in aes-ce-core.S */ asmlinkage u32 ce_aes_sub(u32 input); asmlinkage void ce_aes_invert(void *dst, void *src); asmlinkage void ce_aes_ecb_encrypt(u8 out[], u8 const in[], u32 const rk[], int rounds, int blocks); asmlinkage void ce_aes_ecb_decrypt(u8 out[], u8 const in[], u32 const rk[], int rounds, int blocks); asmlinkage void ce_aes_cbc_encrypt(u8 out[], u8 const in[], u32 const rk[], int rounds, int blocks, u8 iv[]); asmlinkage void ce_aes_cbc_decrypt(u8 out[], u8 const in[], u32 const rk[], int rounds, int blocks, u8 iv[]); asmlinkage void ce_aes_cbc_cts_encrypt(u8 out[], u8 const in[], u32 const rk[], int rounds, int bytes, u8 const iv[]); asmlinkage void ce_aes_cbc_cts_decrypt(u8 out[], u8 const in[], u32 const rk[], int rounds, int bytes, u8 const iv[]); asmlinkage void ce_aes_ctr_encrypt(u8 out[], u8 const in[], u32 const rk[], int rounds, int blocks, u8 ctr[]); asmlinkage void ce_aes_xts_encrypt(u8 out[], u8 const in[], u32 const rk1[], int rounds, int bytes, u8 iv[], u32 const rk2[], int first); asmlinkage void ce_aes_xts_decrypt(u8 out[], u8 const in[], u32 const rk1[], int rounds, int bytes, u8 iv[], u32 const rk2[], int first); struct aes_block { u8 b[AES_BLOCK_SIZE]; }; static int num_rounds(struct crypto_aes_ctx *ctx) { /* * # of rounds specified by AES: * 128 bit key 10 rounds * 192 bit key 12 rounds * 256 bit key 14 rounds * => n byte key => 6 + (n/4) rounds */ return 6 + ctx->key_length / 4; } static int ce_aes_expandkey(struct crypto_aes_ctx *ctx, const u8 *in_key, unsigned int key_len) { /* * The AES key schedule round constants */ static u8 const rcon[] = { 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, }; u32 kwords = key_len / sizeof(u32); struct aes_block *key_enc, *key_dec; int i, j; if (key_len != AES_KEYSIZE_128 && key_len != AES_KEYSIZE_192 && key_len != AES_KEYSIZE_256) return -EINVAL; ctx->key_length = key_len; for (i = 0; i < kwords; i++) ctx->key_enc[i] = get_unaligned_le32(in_key + i * sizeof(u32)); kernel_neon_begin(); for (i = 0; i < sizeof(rcon); i++) { u32 *rki = ctx->key_enc + (i * kwords); u32 *rko = rki + kwords; rko[0] = ror32(ce_aes_sub(rki[kwords - 1]), 8); rko[0] = rko[0] ^ rki[0] ^ rcon[i]; rko[1] = rko[0] ^ rki[1]; rko[2] = rko[1] ^ rki[2]; rko[3] = rko[2] ^ rki[3]; if (key_len == AES_KEYSIZE_192) { if (i >= 7) break; rko[4] = rko[3] ^ rki[4]; rko[5] = rko[4] ^ rki[5]; } else if (key_len == AES_KEYSIZE_256) { if (i >= 6) break; rko[4] = ce_aes_sub(rko[3]) ^ rki[4]; rko[5] = rko[4] ^ rki[5]; rko[6] = rko[5] ^ rki[6]; rko[7] = rko[6] ^ rki[7]; } } /* * Generate the decryption keys for the Equivalent Inverse Cipher. * This involves reversing the order of the round keys, and applying * the Inverse Mix Columns transformation on all but the first and * the last one. */ key_enc = (struct aes_block *)ctx->key_enc; key_dec = (struct aes_block *)ctx->key_dec; j = num_rounds(ctx); key_dec[0] = key_enc[j]; for (i = 1, j--; j > 0; i++, j--) ce_aes_invert(key_dec + i, key_enc + j); key_dec[i] = key_enc[0]; kernel_neon_end(); return 0; } static int ce_aes_setkey(struct crypto_skcipher *tfm, const u8 *in_key, unsigned int key_len) { struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm); int ret; ret = ce_aes_expandkey(ctx, in_key, key_len); if (!ret) return 0; crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN); return -EINVAL; } struct crypto_aes_xts_ctx { struct crypto_aes_ctx key1; struct crypto_aes_ctx __aligned(8) key2; }; static int xts_set_key(struct crypto_skcipher *tfm, const u8 *in_key, unsigned int key_len) { struct crypto_aes_xts_ctx *ctx = crypto_skcipher_ctx(tfm); int ret; ret = xts_verify_key(tfm, in_key, key_len); if (ret) return ret; ret = ce_aes_expandkey(&ctx->key1, in_key, key_len / 2); if (!ret) ret = ce_aes_expandkey(&ctx->key2, &in_key[key_len / 2], key_len / 2); if (!ret) return 0; crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN); return -EINVAL; } static int ecb_encrypt(struct skcipher_request *req) { struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm); struct skcipher_walk walk; unsigned int blocks; int err; err = skcipher_walk_virt(&walk, req, false); while ((blocks = (walk.nbytes / AES_BLOCK_SIZE))) { kernel_neon_begin(); ce_aes_ecb_encrypt(walk.dst.virt.addr, walk.src.virt.addr, ctx->key_enc, num_rounds(ctx), blocks); kernel_neon_end(); err = skcipher_walk_done(&walk, walk.nbytes % AES_BLOCK_SIZE); } return err; } static int ecb_decrypt(struct skcipher_request *req) { struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm); struct skcipher_walk walk; unsigned int blocks; int err; err = skcipher_walk_virt(&walk, req, false); while ((blocks = (walk.nbytes / AES_BLOCK_SIZE))) { kernel_neon_begin(); ce_aes_ecb_decrypt(walk.dst.virt.addr, walk.src.virt.addr, ctx->key_dec, num_rounds(ctx), blocks); kernel_neon_end(); err = skcipher_walk_done(&walk, walk.nbytes % AES_BLOCK_SIZE); } return err; } static int cbc_encrypt_walk(struct skcipher_request *req, struct skcipher_walk *walk) { struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm); unsigned int blocks; int err = 0; while ((blocks = (walk->nbytes / AES_BLOCK_SIZE))) { kernel_neon_begin(); ce_aes_cbc_encrypt(walk->dst.virt.addr, walk->src.virt.addr, ctx->key_enc, num_rounds(ctx), blocks, walk->iv); kernel_neon_end(); err = skcipher_walk_done(walk, walk->nbytes % AES_BLOCK_SIZE); } return err; } static int cbc_encrypt(struct skcipher_request *req) { struct skcipher_walk walk; int err; err = skcipher_walk_virt(&walk, req, false); if (err) return err; return cbc_encrypt_walk(req, &walk); } static int cbc_decrypt_walk(struct skcipher_request *req, struct skcipher_walk *walk) { struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm); unsigned int blocks; int err = 0; while ((blocks = (walk->nbytes / AES_BLOCK_SIZE))) { kernel_neon_begin(); ce_aes_cbc_decrypt(walk->dst.virt.addr, walk->src.virt.addr, ctx->key_dec, num_rounds(ctx), blocks, walk->iv); kernel_neon_end(); err = skcipher_walk_done(walk, walk->nbytes % AES_BLOCK_SIZE); } return err; } static int cbc_decrypt(struct skcipher_request *req) { struct skcipher_walk walk; int err; err = skcipher_walk_virt(&walk, req, false); if (err) return err; return cbc_decrypt_walk(req, &walk); } static int cts_cbc_encrypt(struct skcipher_request *req) { struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm); int cbc_blocks = DIV_ROUND_UP(req->cryptlen, AES_BLOCK_SIZE) - 2; struct scatterlist *src = req->src, *dst = req->dst; struct scatterlist sg_src[2], sg_dst[2]; struct skcipher_request subreq; struct skcipher_walk walk; int err; skcipher_request_set_tfm(&subreq, tfm); skcipher_request_set_callback(&subreq, skcipher_request_flags(req), NULL, NULL); if (req->cryptlen <= AES_BLOCK_SIZE) { if (req->cryptlen < AES_BLOCK_SIZE) return -EINVAL; cbc_blocks = 1; } if (cbc_blocks > 0) { skcipher_request_set_crypt(&subreq, req->src, req->dst, cbc_blocks * AES_BLOCK_SIZE, req->iv); err = skcipher_walk_virt(&walk, &subreq, false) ?: cbc_encrypt_walk(&subreq, &walk); if (err) return err; if (req->cryptlen == AES_BLOCK_SIZE) return 0; dst = src = scatterwalk_ffwd(sg_src, req->src, subreq.cryptlen); if (req->dst != req->src) dst = scatterwalk_ffwd(sg_dst, req->dst, subreq.cryptlen); } /* handle ciphertext stealing */ skcipher_request_set_crypt(&subreq, src, dst, req->cryptlen - cbc_blocks * AES_BLOCK_SIZE, req->iv); err = skcipher_walk_virt(&walk, &subreq, false); if (err) return err; kernel_neon_begin(); ce_aes_cbc_cts_encrypt(walk.dst.virt.addr, walk.src.virt.addr, ctx->key_enc, num_rounds(ctx), walk.nbytes, walk.iv); kernel_neon_end(); return skcipher_walk_done(&walk, 0); } static int cts_cbc_decrypt(struct skcipher_request *req) { struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm); int cbc_blocks = DIV_ROUND_UP(req->cryptlen, AES_BLOCK_SIZE) - 2; struct scatterlist *src = req->src, *dst = req->dst; struct scatterlist sg_src[2], sg_dst[2]; struct skcipher_request subreq; struct skcipher_walk walk; int err; skcipher_request_set_tfm(&subreq, tfm); skcipher_request_set_callback(&subreq, skcipher_request_flags(req), NULL, NULL); if (req->cryptlen <= AES_BLOCK_SIZE) { if (req->cryptlen < AES_BLOCK_SIZE) return -EINVAL; cbc_blocks = 1; } if (cbc_blocks > 0) { skcipher_request_set_crypt(&subreq, req->src, req->dst, cbc_blocks * AES_BLOCK_SIZE, req->iv); err = skcipher_walk_virt(&walk, &subreq, false) ?: cbc_decrypt_walk(&subreq, &walk); if (err) return err; if (req->cryptlen == AES_BLOCK_SIZE) return 0; dst = src = scatterwalk_ffwd(sg_src, req->src, subreq.cryptlen); if (req->dst != req->src) dst = scatterwalk_ffwd(sg_dst, req->dst, subreq.cryptlen); } /* handle ciphertext stealing */ skcipher_request_set_crypt(&subreq, src, dst, req->cryptlen - cbc_blocks * AES_BLOCK_SIZE, req->iv); err = skcipher_walk_virt(&walk, &subreq, false); if (err) return err; kernel_neon_begin(); ce_aes_cbc_cts_decrypt(walk.dst.virt.addr, walk.src.virt.addr, ctx->key_dec, num_rounds(ctx), walk.nbytes, walk.iv); kernel_neon_end(); return skcipher_walk_done(&walk, 0); } static int ctr_encrypt(struct skcipher_request *req) { struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm); struct skcipher_walk walk; int err, blocks; err = skcipher_walk_virt(&walk, req, false); while ((blocks = (walk.nbytes / AES_BLOCK_SIZE))) { kernel_neon_begin(); ce_aes_ctr_encrypt(walk.dst.virt.addr, walk.src.virt.addr, ctx->key_enc, num_rounds(ctx), blocks, walk.iv); kernel_neon_end(); err = skcipher_walk_done(&walk, walk.nbytes % AES_BLOCK_SIZE); } if (walk.nbytes) { u8 __aligned(8) tail[AES_BLOCK_SIZE]; unsigned int nbytes = walk.nbytes; u8 *tdst = walk.dst.virt.addr; u8 *tsrc = walk.src.virt.addr; /* * Tell aes_ctr_encrypt() to process a tail block. */ blocks = -1; kernel_neon_begin(); ce_aes_ctr_encrypt(tail, NULL, ctx->key_enc, num_rounds(ctx), blocks, walk.iv); kernel_neon_end(); crypto_xor_cpy(tdst, tsrc, tail, nbytes); err = skcipher_walk_done(&walk, 0); } return err; } static void ctr_encrypt_one(struct crypto_skcipher *tfm, const u8 *src, u8 *dst) { struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm); unsigned long flags; /* * Temporarily disable interrupts to avoid races where * cachelines are evicted when the CPU is interrupted * to do something else. */ local_irq_save(flags); aes_encrypt(ctx, dst, src); local_irq_restore(flags); } static int ctr_encrypt_sync(struct skcipher_request *req) { if (!crypto_simd_usable()) return crypto_ctr_encrypt_walk(req, ctr_encrypt_one); return ctr_encrypt(req); } static int xts_encrypt(struct skcipher_request *req) { struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); struct crypto_aes_xts_ctx *ctx = crypto_skcipher_ctx(tfm); int err, first, rounds = num_rounds(&ctx->key1); int tail = req->cryptlen % AES_BLOCK_SIZE; struct scatterlist sg_src[2], sg_dst[2]; struct skcipher_request subreq; struct scatterlist *src, *dst; struct skcipher_walk walk; if (req->cryptlen < AES_BLOCK_SIZE) return -EINVAL; err = skcipher_walk_virt(&walk, req, false); if (unlikely(tail > 0 && walk.nbytes < walk.total)) { int xts_blocks = DIV_ROUND_UP(req->cryptlen, AES_BLOCK_SIZE) - 2; skcipher_walk_abort(&walk); skcipher_request_set_tfm(&subreq, tfm); skcipher_request_set_callback(&subreq, skcipher_request_flags(req), NULL, NULL); skcipher_request_set_crypt(&subreq, req->src, req->dst, xts_blocks * AES_BLOCK_SIZE, req->iv); req = &subreq; err = skcipher_walk_virt(&walk, req, false); } else { tail = 0; } for (first = 1; walk.nbytes >= AES_BLOCK_SIZE; first = 0) { int nbytes = walk.nbytes; if (walk.nbytes < walk.total) nbytes &= ~(AES_BLOCK_SIZE - 1); kernel_neon_begin(); ce_aes_xts_encrypt(walk.dst.virt.addr, walk.src.virt.addr, ctx->key1.key_enc, rounds, nbytes, walk.iv, ctx->key2.key_enc, first); kernel_neon_end(); err = skcipher_walk_done(&walk, walk.nbytes - nbytes); } if (err || likely(!tail)) return err; dst = src = scatterwalk_ffwd(sg_src, req->src, req->cryptlen); if (req->dst != req->src) dst = scatterwalk_ffwd(sg_dst, req->dst, req->cryptlen); skcipher_request_set_crypt(req, src, dst, AES_BLOCK_SIZE + tail, req->iv); err = skcipher_walk_virt(&walk, req, false); if (err) return err; kernel_neon_begin(); ce_aes_xts_encrypt(walk.dst.virt.addr, walk.src.virt.addr, ctx->key1.key_enc, rounds, walk.nbytes, walk.iv, ctx->key2.key_enc, first); kernel_neon_end(); return skcipher_walk_done(&walk, 0); } static int xts_decrypt(struct skcipher_request *req) { struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); struct crypto_aes_xts_ctx *ctx = crypto_skcipher_ctx(tfm); int err, first, rounds = num_rounds(&ctx->key1); int tail = req->cryptlen % AES_BLOCK_SIZE; struct scatterlist sg_src[2], sg_dst[2]; struct skcipher_request subreq; struct scatterlist *src, *dst; struct skcipher_walk walk; if (req->cryptlen < AES_BLOCK_SIZE) return -EINVAL; err = skcipher_walk_virt(&walk, req, false); if (unlikely(tail > 0 && walk.nbytes < walk.total)) { int xts_blocks = DIV_ROUND_UP(req->cryptlen, AES_BLOCK_SIZE) - 2; skcipher_walk_abort(&walk); skcipher_request_set_tfm(&subreq, tfm); skcipher_request_set_callback(&subreq, skcipher_request_flags(req), NULL, NULL); skcipher_request_set_crypt(&subreq, req->src, req->dst, xts_blocks * AES_BLOCK_SIZE, req->iv); req = &subreq; err = skcipher_walk_virt(&walk, req, false); } else { tail = 0; } for (first = 1; walk.nbytes >= AES_BLOCK_SIZE; first = 0) { int nbytes = walk.nbytes; if (walk.nbytes < walk.total) nbytes &= ~(AES_BLOCK_SIZE - 1); kernel_neon_begin(); ce_aes_xts_decrypt(walk.dst.virt.addr, walk.src.virt.addr, ctx->key1.key_dec, rounds, nbytes, walk.iv, ctx->key2.key_enc, first); kernel_neon_end(); err = skcipher_walk_done(&walk, walk.nbytes - nbytes); } if (err || likely(!tail)) return err; dst = src = scatterwalk_ffwd(sg_src, req->src, req->cryptlen); if (req->dst != req->src) dst = scatterwalk_ffwd(sg_dst, req->dst, req->cryptlen); skcipher_request_set_crypt(req, src, dst, AES_BLOCK_SIZE + tail, req->iv); err = skcipher_walk_virt(&walk, req, false); if (err) return err; kernel_neon_begin(); ce_aes_xts_decrypt(walk.dst.virt.addr, walk.src.virt.addr, ctx->key1.key_dec, rounds, walk.nbytes, walk.iv, ctx->key2.key_enc, first); kernel_neon_end(); return skcipher_walk_done(&walk, 0); } static struct skcipher_alg aes_algs[] = { { .base.cra_name = "__ecb(aes)", .base.cra_driver_name = "__ecb-aes-ce", .base.cra_priority = 300, .base.cra_flags = CRYPTO_ALG_INTERNAL, .base.cra_blocksize = AES_BLOCK_SIZE, .base.cra_ctxsize = sizeof(struct crypto_aes_ctx), .base.cra_module = THIS_MODULE, .min_keysize = AES_MIN_KEY_SIZE, .max_keysize = AES_MAX_KEY_SIZE, .setkey = ce_aes_setkey, .encrypt = ecb_encrypt, .decrypt = ecb_decrypt, }, { .base.cra_name = "__cbc(aes)", .base.cra_driver_name = "__cbc-aes-ce", .base.cra_priority = 300, .base.cra_flags = CRYPTO_ALG_INTERNAL, .base.cra_blocksize = AES_BLOCK_SIZE, .base.cra_ctxsize = sizeof(struct crypto_aes_ctx), .base.cra_module = THIS_MODULE, .min_keysize = AES_MIN_KEY_SIZE, .max_keysize = AES_MAX_KEY_SIZE, .ivsize = AES_BLOCK_SIZE, .setkey = ce_aes_setkey, .encrypt = cbc_encrypt, .decrypt = cbc_decrypt, }, { .base.cra_name = "__cts(cbc(aes))", .base.cra_driver_name = "__cts-cbc-aes-ce", .base.cra_priority = 300, .base.cra_flags = CRYPTO_ALG_INTERNAL, .base.cra_blocksize = AES_BLOCK_SIZE, .base.cra_ctxsize = sizeof(struct crypto_aes_ctx), .base.cra_module = THIS_MODULE, .min_keysize = AES_MIN_KEY_SIZE, .max_keysize = AES_MAX_KEY_SIZE, .ivsize = AES_BLOCK_SIZE, .walksize = 2 * AES_BLOCK_SIZE, .setkey = ce_aes_setkey, .encrypt = cts_cbc_encrypt, .decrypt = cts_cbc_decrypt, }, { .base.cra_name = "__ctr(aes)", .base.cra_driver_name = "__ctr-aes-ce", .base.cra_priority = 300, .base.cra_flags = CRYPTO_ALG_INTERNAL, .base.cra_blocksize = 1, .base.cra_ctxsize = sizeof(struct crypto_aes_ctx), .base.cra_module = THIS_MODULE, .min_keysize = AES_MIN_KEY_SIZE, .max_keysize = AES_MAX_KEY_SIZE, .ivsize = AES_BLOCK_SIZE, .chunksize = AES_BLOCK_SIZE, .setkey = ce_aes_setkey, .encrypt = ctr_encrypt, .decrypt = ctr_encrypt, }, { .base.cra_name = "ctr(aes)", .base.cra_driver_name = "ctr-aes-ce-sync", .base.cra_priority = 300 - 1, .base.cra_blocksize = 1, .base.cra_ctxsize = sizeof(struct crypto_aes_ctx), .base.cra_module = THIS_MODULE, .min_keysize = AES_MIN_KEY_SIZE, .max_keysize = AES_MAX_KEY_SIZE, .ivsize = AES_BLOCK_SIZE, .chunksize = AES_BLOCK_SIZE, .setkey = ce_aes_setkey, .encrypt = ctr_encrypt_sync, .decrypt = ctr_encrypt_sync, }, { .base.cra_name = "__xts(aes)", .base.cra_driver_name = "__xts-aes-ce", .base.cra_priority = 300, .base.cra_flags = CRYPTO_ALG_INTERNAL, .base.cra_blocksize = AES_BLOCK_SIZE, .base.cra_ctxsize = sizeof(struct crypto_aes_xts_ctx), .base.cra_module = THIS_MODULE, .min_keysize = 2 * AES_MIN_KEY_SIZE, .max_keysize = 2 * AES_MAX_KEY_SIZE, .ivsize = AES_BLOCK_SIZE, .walksize = 2 * AES_BLOCK_SIZE, .setkey = xts_set_key, .encrypt = xts_encrypt, .decrypt = xts_decrypt, } }; static struct simd_skcipher_alg *aes_simd_algs[ARRAY_SIZE(aes_algs)]; static void aes_exit(void) { int i; for (i = 0; i < ARRAY_SIZE(aes_simd_algs) && aes_simd_algs[i]; i++) simd_skcipher_free(aes_simd_algs[i]); crypto_unregister_skciphers(aes_algs, ARRAY_SIZE(aes_algs)); } static int __init aes_init(void) { struct simd_skcipher_alg *simd; const char *basename; const char *algname; const char *drvname; int err; int i; err = crypto_register_skciphers(aes_algs, ARRAY_SIZE(aes_algs)); if (err) return err; for (i = 0; i < ARRAY_SIZE(aes_algs); i++) { if (!(aes_algs[i].base.cra_flags & CRYPTO_ALG_INTERNAL)) continue; algname = aes_algs[i].base.cra_name + 2; drvname = aes_algs[i].base.cra_driver_name + 2; basename = aes_algs[i].base.cra_driver_name; simd = simd_skcipher_create_compat(algname, drvname, basename); err = PTR_ERR(simd); if (IS_ERR(simd)) goto unregister_simds; aes_simd_algs[i] = simd; } return 0; unregister_simds: aes_exit(); return err; } module_cpu_feature_match(AES, aes_init); module_exit(aes_exit);