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 --- lib/digsig.c | 244 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 244 insertions(+) create mode 100644 lib/digsig.c (limited to 'lib/digsig.c') diff --git a/lib/digsig.c b/lib/digsig.c new file mode 100644 index 000000000..9dd319c12 --- /dev/null +++ b/lib/digsig.c @@ -0,0 +1,244 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2011 Nokia Corporation + * Copyright (C) 2011 Intel Corporation + * + * Author: + * Dmitry Kasatkin + * + * + * File: sign.c + * implements signature (RSA) verification + * pkcs decoding is based on LibTomCrypt code + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include +#include +#include +#include +#include +#include + +static const char *pkcs_1_v1_5_decode_emsa(const unsigned char *msg, + unsigned long msglen, + unsigned long modulus_bitlen, + unsigned long *outlen) +{ + unsigned long modulus_len, ps_len, i; + + modulus_len = (modulus_bitlen >> 3) + (modulus_bitlen & 7 ? 1 : 0); + + /* test message size */ + if ((msglen > modulus_len) || (modulus_len < 11)) + return NULL; + + /* separate encoded message */ + if (msg[0] != 0x00 || msg[1] != 0x01) + return NULL; + + for (i = 2; i < modulus_len - 1; i++) + if (msg[i] != 0xFF) + break; + + /* separator check */ + if (msg[i] != 0) + /* There was no octet with hexadecimal value 0x00 + to separate ps from m. */ + return NULL; + + ps_len = i - 2; + + *outlen = (msglen - (2 + ps_len + 1)); + + return msg + 2 + ps_len + 1; +} + +/* + * RSA Signature verification with public key + */ +static int digsig_verify_rsa(struct key *key, + const char *sig, int siglen, + const char *h, int hlen) +{ + int err = -EINVAL; + unsigned long len; + unsigned long mlen, mblen; + unsigned nret, l; + int head, i; + unsigned char *out1 = NULL; + const char *m; + MPI in = NULL, res = NULL, pkey[2]; + uint8_t *p, *datap; + const uint8_t *endp; + const struct user_key_payload *ukp; + struct pubkey_hdr *pkh; + + down_read(&key->sem); + ukp = user_key_payload_locked(key); + + if (!ukp) { + /* key was revoked before we acquired its semaphore */ + err = -EKEYREVOKED; + goto err1; + } + + if (ukp->datalen < sizeof(*pkh)) + goto err1; + + pkh = (struct pubkey_hdr *)ukp->data; + + if (pkh->version != 1) + goto err1; + + if (pkh->algo != PUBKEY_ALGO_RSA) + goto err1; + + if (pkh->nmpi != 2) + goto err1; + + datap = pkh->mpi; + endp = ukp->data + ukp->datalen; + + for (i = 0; i < pkh->nmpi; i++) { + unsigned int remaining = endp - datap; + pkey[i] = mpi_read_from_buffer(datap, &remaining); + if (IS_ERR(pkey[i])) { + err = PTR_ERR(pkey[i]); + goto err; + } + datap += remaining; + } + + mblen = mpi_get_nbits(pkey[0]); + mlen = DIV_ROUND_UP(mblen, 8); + + if (mlen == 0) { + err = -EINVAL; + goto err; + } + + err = -ENOMEM; + + out1 = kzalloc(mlen, GFP_KERNEL); + if (!out1) + goto err; + + nret = siglen; + in = mpi_read_from_buffer(sig, &nret); + if (IS_ERR(in)) { + err = PTR_ERR(in); + goto err; + } + + res = mpi_alloc(mpi_get_nlimbs(in) * 2); + if (!res) + goto err; + + err = mpi_powm(res, in, pkey[1], pkey[0]); + if (err) + goto err; + + if (mpi_get_nlimbs(res) * BYTES_PER_MPI_LIMB > mlen) { + err = -EINVAL; + goto err; + } + + p = mpi_get_buffer(res, &l, NULL); + if (!p) { + err = -EINVAL; + goto err; + } + + len = mlen; + head = len - l; + memcpy(out1 + head, p, l); + + kfree(p); + + m = pkcs_1_v1_5_decode_emsa(out1, len, mblen, &len); + + if (!m || len != hlen || memcmp(m, h, hlen)) + err = -EINVAL; + +err: + mpi_free(in); + mpi_free(res); + kfree(out1); + while (--i >= 0) + mpi_free(pkey[i]); +err1: + up_read(&key->sem); + + return err; +} + +/** + * digsig_verify() - digital signature verification with public key + * @keyring: keyring to search key in + * @sig: digital signature + * @siglen: length of the signature + * @data: data + * @datalen: length of the data + * + * Returns 0 on success, -EINVAL otherwise + * + * Verifies data integrity against digital signature. + * Currently only RSA is supported. + * Normally hash of the content is used as a data for this function. + * + */ +int digsig_verify(struct key *keyring, const char *sig, int siglen, + const char *data, int datalen) +{ + struct signature_hdr *sh = (struct signature_hdr *)sig; + struct sha1_ctx ctx; + unsigned char hash[SHA1_DIGEST_SIZE]; + struct key *key; + char name[20]; + int err; + + if (siglen < sizeof(*sh) + 2) + return -EINVAL; + + if (sh->algo != PUBKEY_ALGO_RSA) + return -ENOTSUPP; + + sprintf(name, "%llX", __be64_to_cpup((uint64_t *)sh->keyid)); + + if (keyring) { + /* search in specific keyring */ + key_ref_t kref; + kref = keyring_search(make_key_ref(keyring, 1UL), + &key_type_user, name, true); + if (IS_ERR(kref)) + key = ERR_CAST(kref); + else + key = key_ref_to_ptr(kref); + } else { + key = request_key(&key_type_user, name, NULL); + } + if (IS_ERR(key)) { + pr_err("key not found, id: %s\n", name); + return PTR_ERR(key); + } + + sha1_init(&ctx); + sha1_update(&ctx, data, datalen); + sha1_update(&ctx, sig, sizeof(*sh)); + sha1_final(&ctx, hash); + + /* pass signature mpis address */ + err = digsig_verify_rsa(key, sig + sizeof(*sh), siglen - sizeof(*sh), + hash, sizeof(hash)); + + key_put(key); + + return err ? -EINVAL : 0; +} +EXPORT_SYMBOL_GPL(digsig_verify); + +MODULE_LICENSE("GPL"); -- cgit v1.3.1