143 lines
2.9 KiB
C
143 lines
2.9 KiB
C
/*
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* Copyright (C) 2005,2006,2007,2008 IBM Corporation
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*
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* Authors:
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* Mimi Zohar <zohar@us.ibm.com>
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* Kylene Hall <kjhall@us.ibm.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: ima_crypto.c
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* Calculates md5/sha1 file hash, template hash, boot-aggreate hash
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*/
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#include <linux/kernel.h>
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#include <linux/file.h>
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#include <linux/crypto.h>
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#include <linux/scatterlist.h>
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#include <linux/err.h>
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#include "ima.h"
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static int init_desc(struct hash_desc *desc)
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{
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int rc;
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desc->tfm = crypto_alloc_hash(ima_hash, 0, CRYPTO_ALG_ASYNC);
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if (IS_ERR(desc->tfm)) {
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pr_info("failed to load %s transform: %ld\n",
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ima_hash, PTR_ERR(desc->tfm));
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rc = PTR_ERR(desc->tfm);
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return rc;
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}
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desc->flags = 0;
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rc = crypto_hash_init(desc);
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if (rc)
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crypto_free_hash(desc->tfm);
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return rc;
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}
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/*
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* Calculate the MD5/SHA1 file digest
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*/
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int ima_calc_hash(struct file *file, char *digest)
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{
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struct hash_desc desc;
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struct scatterlist sg[1];
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loff_t i_size, offset = 0;
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char *rbuf;
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int rc;
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rc = init_desc(&desc);
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if (rc != 0)
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return rc;
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rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL);
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if (!rbuf) {
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rc = -ENOMEM;
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goto out;
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}
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i_size = i_size_read(file->f_dentry->d_inode);
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while (offset < i_size) {
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int rbuf_len;
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rbuf_len = kernel_read(file, offset, rbuf, PAGE_SIZE);
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if (rbuf_len < 0) {
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rc = rbuf_len;
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break;
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}
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if (rbuf_len == 0)
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break;
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offset += rbuf_len;
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sg_init_one(sg, rbuf, rbuf_len);
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rc = crypto_hash_update(&desc, sg, rbuf_len);
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if (rc)
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break;
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}
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kfree(rbuf);
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if (!rc)
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rc = crypto_hash_final(&desc, digest);
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out:
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crypto_free_hash(desc.tfm);
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return rc;
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}
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/*
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* Calculate the hash of a given template
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*/
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int ima_calc_template_hash(int template_len, void *template, char *digest)
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{
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struct hash_desc desc;
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struct scatterlist sg[1];
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int rc;
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rc = init_desc(&desc);
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if (rc != 0)
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return rc;
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sg_init_one(sg, template, template_len);
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rc = crypto_hash_update(&desc, sg, template_len);
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if (!rc)
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rc = crypto_hash_final(&desc, digest);
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crypto_free_hash(desc.tfm);
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return rc;
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}
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static void __init ima_pcrread(int idx, u8 *pcr)
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{
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if (!ima_used_chip)
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return;
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if (tpm_pcr_read(TPM_ANY_NUM, idx, pcr) != 0)
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pr_err("Error Communicating to TPM chip\n");
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}
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/*
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* Calculate the boot aggregate hash
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*/
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int __init ima_calc_boot_aggregate(char *digest)
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{
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struct hash_desc desc;
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struct scatterlist sg;
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u8 pcr_i[IMA_DIGEST_SIZE];
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int rc, i;
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rc = init_desc(&desc);
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if (rc != 0)
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return rc;
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/* cumulative sha1 over tpm registers 0-7 */
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for (i = TPM_PCR0; i < TPM_PCR8; i++) {
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ima_pcrread(i, pcr_i);
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/* now accumulate with current aggregate */
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sg_init_one(&sg, pcr_i, IMA_DIGEST_SIZE);
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rc = crypto_hash_update(&desc, &sg, IMA_DIGEST_SIZE);
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}
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if (!rc)
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crypto_hash_final(&desc, digest);
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crypto_free_hash(desc.tfm);
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return rc;
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}
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