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![Fabian Frederick](/assets/img/avatar_default.png)
Small typo and @return: -> Returns ... Signed-off-by: Fabian Frederick <fabf@skynet.be> Cc: Duan Jiong <duanj.fnst@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
270 lines
5.5 KiB
C
270 lines
5.5 KiB
C
/*
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* Copyright (C) 2011 Nokia Corporation
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* Copyright (C) 2011 Intel Corporation
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*
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* Author:
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* Dmitry Kasatkin <dmitry.kasatkin@nokia.com>
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* <dmitry.kasatkin@intel.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, version 2 of the License.
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*
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* File: sign.c
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* implements signature (RSA) verification
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* pkcs decoding is based on LibTomCrypt code
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/err.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/key.h>
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#include <linux/crypto.h>
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#include <crypto/hash.h>
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#include <crypto/sha.h>
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#include <keys/user-type.h>
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#include <linux/mpi.h>
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#include <linux/digsig.h>
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static struct crypto_shash *shash;
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static const char *pkcs_1_v1_5_decode_emsa(const unsigned char *msg,
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unsigned long msglen,
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unsigned long modulus_bitlen,
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unsigned long *outlen)
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{
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unsigned long modulus_len, ps_len, i;
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modulus_len = (modulus_bitlen >> 3) + (modulus_bitlen & 7 ? 1 : 0);
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/* test message size */
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if ((msglen > modulus_len) || (modulus_len < 11))
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return NULL;
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/* separate encoded message */
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if (msg[0] != 0x00 || msg[1] != 0x01)
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return NULL;
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for (i = 2; i < modulus_len - 1; i++)
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if (msg[i] != 0xFF)
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break;
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/* separator check */
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if (msg[i] != 0)
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/* There was no octet with hexadecimal value 0x00
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to separate ps from m. */
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return NULL;
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ps_len = i - 2;
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*outlen = (msglen - (2 + ps_len + 1));
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return msg + 2 + ps_len + 1;
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}
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/*
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* RSA Signature verification with public key
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*/
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static int digsig_verify_rsa(struct key *key,
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const char *sig, int siglen,
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const char *h, int hlen)
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{
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int err = -EINVAL;
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unsigned long len;
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unsigned long mlen, mblen;
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unsigned nret, l;
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int head, i;
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unsigned char *out1 = NULL;
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const char *m;
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MPI in = NULL, res = NULL, pkey[2];
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uint8_t *p, *datap, *endp;
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struct user_key_payload *ukp;
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struct pubkey_hdr *pkh;
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down_read(&key->sem);
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ukp = key->payload.data;
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if (ukp->datalen < sizeof(*pkh))
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goto err1;
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pkh = (struct pubkey_hdr *)ukp->data;
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if (pkh->version != 1)
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goto err1;
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if (pkh->algo != PUBKEY_ALGO_RSA)
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goto err1;
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if (pkh->nmpi != 2)
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goto err1;
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datap = pkh->mpi;
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endp = ukp->data + ukp->datalen;
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err = -ENOMEM;
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for (i = 0; i < pkh->nmpi; i++) {
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unsigned int remaining = endp - datap;
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pkey[i] = mpi_read_from_buffer(datap, &remaining);
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if (!pkey[i])
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goto err;
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datap += remaining;
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}
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mblen = mpi_get_nbits(pkey[0]);
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mlen = DIV_ROUND_UP(mblen, 8);
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if (mlen == 0)
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goto err;
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out1 = kzalloc(mlen, GFP_KERNEL);
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if (!out1)
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goto err;
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nret = siglen;
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in = mpi_read_from_buffer(sig, &nret);
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if (!in)
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goto err;
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res = mpi_alloc(mpi_get_nlimbs(in) * 2);
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if (!res)
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goto err;
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err = mpi_powm(res, in, pkey[1], pkey[0]);
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if (err)
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goto err;
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if (mpi_get_nlimbs(res) * BYTES_PER_MPI_LIMB > mlen) {
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err = -EINVAL;
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goto err;
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}
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p = mpi_get_buffer(res, &l, NULL);
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if (!p) {
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err = -EINVAL;
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goto err;
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}
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len = mlen;
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head = len - l;
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memset(out1, 0, head);
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memcpy(out1 + head, p, l);
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kfree(p);
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m = pkcs_1_v1_5_decode_emsa(out1, len, mblen, &len);
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if (!m || len != hlen || memcmp(m, h, hlen))
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err = -EINVAL;
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err:
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mpi_free(in);
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mpi_free(res);
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kfree(out1);
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while (--i >= 0)
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mpi_free(pkey[i]);
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err1:
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up_read(&key->sem);
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return err;
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}
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/**
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* digsig_verify() - digital signature verification with public key
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* @keyring: keyring to search key in
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* @sig: digital signature
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* @siglen: length of the signature
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* @data: data
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* @datalen: length of the data
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*
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* Returns 0 on success, -EINVAL otherwise
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*
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* Verifies data integrity against digital signature.
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* Currently only RSA is supported.
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* Normally hash of the content is used as a data for this function.
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*
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*/
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int digsig_verify(struct key *keyring, const char *sig, int siglen,
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const char *data, int datalen)
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{
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int err = -ENOMEM;
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struct signature_hdr *sh = (struct signature_hdr *)sig;
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struct shash_desc *desc = NULL;
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unsigned char hash[SHA1_DIGEST_SIZE];
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struct key *key;
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char name[20];
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if (siglen < sizeof(*sh) + 2)
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return -EINVAL;
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if (sh->algo != PUBKEY_ALGO_RSA)
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return -ENOTSUPP;
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sprintf(name, "%llX", __be64_to_cpup((uint64_t *)sh->keyid));
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if (keyring) {
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/* search in specific keyring */
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key_ref_t kref;
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kref = keyring_search(make_key_ref(keyring, 1UL),
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&key_type_user, name);
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if (IS_ERR(kref))
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key = ERR_CAST(kref);
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else
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key = key_ref_to_ptr(kref);
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} else {
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key = request_key(&key_type_user, name, NULL);
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}
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if (IS_ERR(key)) {
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pr_err("key not found, id: %s\n", name);
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return PTR_ERR(key);
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}
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desc = kzalloc(sizeof(*desc) + crypto_shash_descsize(shash),
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GFP_KERNEL);
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if (!desc)
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goto err;
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desc->tfm = shash;
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desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
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crypto_shash_init(desc);
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crypto_shash_update(desc, data, datalen);
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crypto_shash_update(desc, sig, sizeof(*sh));
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crypto_shash_final(desc, hash);
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kfree(desc);
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/* pass signature mpis address */
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err = digsig_verify_rsa(key, sig + sizeof(*sh), siglen - sizeof(*sh),
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hash, sizeof(hash));
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err:
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key_put(key);
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return err ? -EINVAL : 0;
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}
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EXPORT_SYMBOL_GPL(digsig_verify);
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static int __init digsig_init(void)
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{
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shash = crypto_alloc_shash("sha1", 0, 0);
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if (IS_ERR(shash)) {
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pr_err("shash allocation failed\n");
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return PTR_ERR(shash);
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}
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return 0;
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}
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static void __exit digsig_cleanup(void)
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{
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crypto_free_shash(shash);
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}
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module_init(digsig_init);
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module_exit(digsig_cleanup);
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MODULE_LICENSE("GPL");
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