| /* |
| * Copyright (C) 2005,2006,2007,2008 IBM Corporation |
| * |
| * Authors: |
| * Mimi Zohar <zohar@us.ibm.com> |
| * Kylene Hall <kjhall@us.ibm.com> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation, version 2 of the License. |
| * |
| * File: ima_crypto.c |
| * Calculates md5/sha1 file hash, template hash, boot-aggreate hash |
| */ |
| |
| #include <linux/kernel.h> |
| #include <linux/file.h> |
| #include <linux/crypto.h> |
| #include <linux/scatterlist.h> |
| #include <linux/err.h> |
| #include <linux/slab.h> |
| #include "ima.h" |
| |
| static int init_desc(struct hash_desc *desc) |
| { |
| int rc; |
| |
| desc->tfm = crypto_alloc_hash(ima_hash, 0, CRYPTO_ALG_ASYNC); |
| if (IS_ERR(desc->tfm)) { |
| pr_info("failed to load %s transform: %ld\n", |
| ima_hash, PTR_ERR(desc->tfm)); |
| rc = PTR_ERR(desc->tfm); |
| return rc; |
| } |
| desc->flags = 0; |
| rc = crypto_hash_init(desc); |
| if (rc) |
| crypto_free_hash(desc->tfm); |
| return rc; |
| } |
| |
| /* |
| * Calculate the MD5/SHA1 file digest |
| */ |
| int ima_calc_hash(struct file *file, char *digest) |
| { |
| struct hash_desc desc; |
| struct scatterlist sg[1]; |
| loff_t i_size, offset = 0; |
| char *rbuf; |
| int rc; |
| |
| rc = init_desc(&desc); |
| if (rc != 0) |
| return rc; |
| |
| rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL); |
| if (!rbuf) { |
| rc = -ENOMEM; |
| goto out; |
| } |
| i_size = i_size_read(file->f_dentry->d_inode); |
| while (offset < i_size) { |
| int rbuf_len; |
| |
| rbuf_len = kernel_read(file, offset, rbuf, PAGE_SIZE); |
| if (rbuf_len < 0) { |
| rc = rbuf_len; |
| break; |
| } |
| if (rbuf_len == 0) |
| break; |
| offset += rbuf_len; |
| sg_init_one(sg, rbuf, rbuf_len); |
| |
| rc = crypto_hash_update(&desc, sg, rbuf_len); |
| if (rc) |
| break; |
| } |
| kfree(rbuf); |
| if (!rc) |
| rc = crypto_hash_final(&desc, digest); |
| out: |
| crypto_free_hash(desc.tfm); |
| return rc; |
| } |
| |
| /* |
| * Calculate the hash of a given template |
| */ |
| int ima_calc_template_hash(int template_len, void *template, char *digest) |
| { |
| struct hash_desc desc; |
| struct scatterlist sg[1]; |
| int rc; |
| |
| rc = init_desc(&desc); |
| if (rc != 0) |
| return rc; |
| |
| sg_init_one(sg, template, template_len); |
| rc = crypto_hash_update(&desc, sg, template_len); |
| if (!rc) |
| rc = crypto_hash_final(&desc, digest); |
| crypto_free_hash(desc.tfm); |
| return rc; |
| } |
| |
| static void __init ima_pcrread(int idx, u8 *pcr) |
| { |
| if (!ima_used_chip) |
| return; |
| |
| if (tpm_pcr_read(TPM_ANY_NUM, idx, pcr) != 0) |
| pr_err("Error Communicating to TPM chip\n"); |
| } |
| |
| /* |
| * Calculate the boot aggregate hash |
| */ |
| int __init ima_calc_boot_aggregate(char *digest) |
| { |
| struct hash_desc desc; |
| struct scatterlist sg; |
| u8 pcr_i[IMA_DIGEST_SIZE]; |
| int rc, i; |
| |
| rc = init_desc(&desc); |
| if (rc != 0) |
| return rc; |
| |
| /* cumulative sha1 over tpm registers 0-7 */ |
| for (i = TPM_PCR0; i < TPM_PCR8; i++) { |
| ima_pcrread(i, pcr_i); |
| /* now accumulate with current aggregate */ |
| sg_init_one(&sg, pcr_i, IMA_DIGEST_SIZE); |
| rc = crypto_hash_update(&desc, &sg, IMA_DIGEST_SIZE); |
| } |
| if (!rc) |
| crypto_hash_final(&desc, digest); |
| crypto_free_hash(desc.tfm); |
| return rc; |
| } |