From 3323eec921efd815178a23107ab63588c605c0b2 Mon Sep 17 00:00:00 2001 From: Mimi Zohar Date: Wed, 4 Feb 2009 09:06:58 -0500 Subject: integrity: IMA as an integrity service provider IMA provides hardware (TPM) based measurement and attestation for file measurements. As the Trusted Computing (TPM) model requires, IMA measures all files before they are accessed in any way (on the integrity_bprm_check, integrity_path_check and integrity_file_mmap hooks), and commits the measurements to the TPM. Once added to the TPM, measurements can not be removed. In addition, IMA maintains a list of these file measurements, which can be used to validate the aggregate value stored in the TPM. The TPM can sign these measurements, and thus the system can prove, to itself and to a third party, the system's integrity in a way that cannot be circumvented by malicious or compromised software. - alloc ima_template_entry before calling ima_store_template() - log ima_add_boot_aggregate() failure - removed unused IMA_TEMPLATE_NAME_LEN - replaced hard coded string length with #define name Signed-off-by: Mimi Zohar Signed-off-by: James Morris --- security/integrity/ima/ima_crypto.c | 140 ++++++++++++++++++++++++++++++++++++ 1 file changed, 140 insertions(+) create mode 100644 security/integrity/ima/ima_crypto.c (limited to 'security/integrity/ima/ima_crypto.c') diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c new file mode 100644 index 00000000000..c2a46e40999 --- /dev/null +++ b/security/integrity/ima/ima_crypto.c @@ -0,0 +1,140 @@ +/* + * Copyright (C) 2005,2006,2007,2008 IBM Corporation + * + * Authors: + * Mimi Zohar + * Kylene Hall + * + * 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 +#include +#include +#include +#include +#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; + char *rbuf; + int rc, offset = 0; + + 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; + } + offset += rbuf_len; + sg_set_buf(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_set_buf(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 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 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; +} -- cgit v1.2.3