From e8dd273d199f5bbe295a8e3d8b777c5505b6b2e1 Mon Sep 17 00:00:00 2001 From: Salah Triki Date: Thu, 17 Sep 2026 14:00:52 +0100 Subject: iio: proximity: isl29501: Fix return type of isl29501_register_write isl29501_register_write() was returning a u32 instead of an int. Since the function returns negative error codes (such as -ERANGE or return values from i2c_smbus_write_byte_data()), returning an unsigned integer type prevents callers from correctly checking for negative error conditions. Fix this by changing the function return type from u32 to int. This was found through manual code review. Fixes: 1c28799257bc ("iio: light: isl29501: Add support for the ISL29501 ToF sensor.") Signed-off-by: Salah Triki Reviewed-by: Joshua Crofts Cc: stable@vger.kernel.org Signed-off-by: Jonathan Cameron --- crypto/xctr.c | 191 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 191 insertions(+) create mode 100644 crypto/xctr.c (limited to 'crypto/xctr.c') diff --git a/crypto/xctr.c b/crypto/xctr.c new file mode 100644 index 000000000..607ab82cb --- /dev/null +++ b/crypto/xctr.c @@ -0,0 +1,191 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * XCTR: XOR Counter mode - Adapted from ctr.c + * + * (C) Copyright IBM Corp. 2007 - Joy Latten + * Copyright 2021 Google LLC + */ + +/* + * XCTR mode is a blockcipher mode of operation used to implement HCTR2. XCTR is + * closely related to the CTR mode of operation; the main difference is that CTR + * generates the keystream using E(CTR + IV) whereas XCTR generates the + * keystream using E(CTR ^ IV). This allows implementations to avoid dealing + * with multi-limb integers (as is required in CTR mode). XCTR is also specified + * using little-endian arithmetic which makes it slightly faster on LE machines. + * + * See the HCTR2 paper for more details: + * Length-preserving encryption with HCTR2 + * (https://eprint.iacr.org/2021/1441.pdf) + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +/* For now this implementation is limited to 16-byte blocks for simplicity */ +#define XCTR_BLOCKSIZE 16 + +static void crypto_xctr_crypt_final(struct skcipher_walk *walk, + struct crypto_cipher *tfm, u32 byte_ctr) +{ + u8 keystream[XCTR_BLOCKSIZE]; + const u8 *src = walk->src.virt.addr; + u8 *dst = walk->dst.virt.addr; + unsigned int nbytes = walk->nbytes; + __le32 ctr32 = cpu_to_le32(byte_ctr / XCTR_BLOCKSIZE + 1); + + crypto_xor(walk->iv, (u8 *)&ctr32, sizeof(ctr32)); + crypto_cipher_encrypt_one(tfm, keystream, walk->iv); + crypto_xor_cpy(dst, keystream, src, nbytes); + crypto_xor(walk->iv, (u8 *)&ctr32, sizeof(ctr32)); +} + +static int crypto_xctr_crypt_segment(struct skcipher_walk *walk, + struct crypto_cipher *tfm, u32 byte_ctr) +{ + void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = + crypto_cipher_alg(tfm)->cia_encrypt; + const u8 *src = walk->src.virt.addr; + u8 *dst = walk->dst.virt.addr; + unsigned int nbytes = walk->nbytes; + __le32 ctr32 = cpu_to_le32(byte_ctr / XCTR_BLOCKSIZE + 1); + + do { + crypto_xor(walk->iv, (u8 *)&ctr32, sizeof(ctr32)); + fn(crypto_cipher_tfm(tfm), dst, walk->iv); + crypto_xor(dst, src, XCTR_BLOCKSIZE); + crypto_xor(walk->iv, (u8 *)&ctr32, sizeof(ctr32)); + + le32_add_cpu(&ctr32, 1); + + src += XCTR_BLOCKSIZE; + dst += XCTR_BLOCKSIZE; + } while ((nbytes -= XCTR_BLOCKSIZE) >= XCTR_BLOCKSIZE); + + return nbytes; +} + +static int crypto_xctr_crypt_inplace(struct skcipher_walk *walk, + struct crypto_cipher *tfm, u32 byte_ctr) +{ + void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = + crypto_cipher_alg(tfm)->cia_encrypt; + unsigned long alignmask = crypto_cipher_alignmask(tfm); + unsigned int nbytes = walk->nbytes; + u8 *data = walk->dst.virt.addr; + u8 tmp[XCTR_BLOCKSIZE + MAX_CIPHER_ALIGNMASK]; + u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1); + __le32 ctr32 = cpu_to_le32(byte_ctr / XCTR_BLOCKSIZE + 1); + + do { + crypto_xor(walk->iv, (u8 *)&ctr32, sizeof(ctr32)); + fn(crypto_cipher_tfm(tfm), keystream, walk->iv); + crypto_xor(data, keystream, XCTR_BLOCKSIZE); + crypto_xor(walk->iv, (u8 *)&ctr32, sizeof(ctr32)); + + le32_add_cpu(&ctr32, 1); + + data += XCTR_BLOCKSIZE; + } while ((nbytes -= XCTR_BLOCKSIZE) >= XCTR_BLOCKSIZE); + + return nbytes; +} + +static int crypto_xctr_crypt(struct skcipher_request *req) +{ + struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); + struct crypto_cipher *cipher = skcipher_cipher_simple(tfm); + struct skcipher_walk walk; + unsigned int nbytes; + int err; + u32 byte_ctr = 0; + + err = skcipher_walk_virt(&walk, req, false); + + while (walk.nbytes >= XCTR_BLOCKSIZE) { + if (walk.src.virt.addr == walk.dst.virt.addr) + nbytes = crypto_xctr_crypt_inplace(&walk, cipher, + byte_ctr); + else + nbytes = crypto_xctr_crypt_segment(&walk, cipher, + byte_ctr); + + byte_ctr += walk.nbytes - nbytes; + err = skcipher_walk_done(&walk, nbytes); + } + + if (walk.nbytes) { + crypto_xctr_crypt_final(&walk, cipher, byte_ctr); + err = skcipher_walk_done(&walk, 0); + } + + return err; +} + +static int crypto_xctr_create(struct crypto_template *tmpl, struct rtattr **tb) +{ + struct skcipher_instance *inst; + struct crypto_alg *alg; + int err; + + inst = skcipher_alloc_instance_simple(tmpl, tb); + if (IS_ERR(inst)) + return PTR_ERR(inst); + + alg = skcipher_ialg_simple(inst); + + /* Block size must be 16 bytes. */ + err = -EINVAL; + if (alg->cra_blocksize != XCTR_BLOCKSIZE) + goto out_free_inst; + + /* XCTR mode is a stream cipher. */ + inst->alg.base.cra_blocksize = 1; + + /* + * To simplify the implementation, configure the skcipher walk to only + * give a partial block at the very end, never earlier. + */ + inst->alg.chunksize = alg->cra_blocksize; + + inst->alg.encrypt = crypto_xctr_crypt; + inst->alg.decrypt = crypto_xctr_crypt; + + err = skcipher_register_instance(tmpl, inst); + if (err) { +out_free_inst: + inst->free(inst); + } + + return err; +} + +static struct crypto_template crypto_xctr_tmpl = { + .name = "xctr", + .create = crypto_xctr_create, + .module = THIS_MODULE, +}; + +static int __init crypto_xctr_module_init(void) +{ + return crypto_register_template(&crypto_xctr_tmpl); +} + +static void __exit crypto_xctr_module_exit(void) +{ + crypto_unregister_template(&crypto_xctr_tmpl); +} + +module_init(crypto_xctr_module_init); +module_exit(crypto_xctr_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("XCTR block cipher mode of operation"); +MODULE_ALIAS_CRYPTO("xctr"); +MODULE_IMPORT_NS("CRYPTO_INTERNAL"); -- cgit v1.3.1