2 * Copyright (C) 2005,2006,2007,2008 IBM Corporation
5 * Mimi Zohar <zohar@us.ibm.com>
6 * Kylene Hall <kjhall@us.ibm.com>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation, version 2 of the License.
13 * Calculates md5/sha1 file hash, template hash, boot-aggreate hash
16 #include <linux/kernel.h>
17 #include <linux/file.h>
18 #include <linux/crypto.h>
19 #include <linux/scatterlist.h>
20 #include <linux/err.h>
21 #include <linux/slab.h>
22 #include <crypto/hash.h>
25 static struct crypto_shash *ima_shash_tfm;
28 * ima_kernel_read - read file content
30 * This is a function for reading file content instead of kernel_read().
31 * It does not perform locking checks to ensure it cannot be blocked.
32 * It does not perform security checks because it is irrelevant for IMA.
35 static int ima_kernel_read(struct file *file, loff_t offset,
36 char *addr, unsigned long count)
39 char __user *buf = addr;
42 if (!(file->f_mode & FMODE_READ))
44 if (!file->f_op->read && !file->f_op->aio_read)
50 ret = file->f_op->read(file, buf, count, &offset);
52 ret = do_sync_read(file, buf, count, &offset);
57 int ima_init_crypto(void)
61 ima_shash_tfm = crypto_alloc_shash(ima_hash, 0, 0);
62 if (IS_ERR(ima_shash_tfm)) {
63 rc = PTR_ERR(ima_shash_tfm);
64 pr_err("Can not allocate %s (reason: %ld)\n", ima_hash, rc);
71 * Calculate the MD5/SHA1 file digest
73 int ima_calc_file_hash(struct file *file, char *digest)
75 loff_t i_size, offset = 0;
79 struct shash_desc shash;
80 char ctx[crypto_shash_descsize(ima_shash_tfm)];
83 desc.shash.tfm = ima_shash_tfm;
86 rc = crypto_shash_init(&desc.shash);
90 rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL);
95 if (!(file->f_mode & FMODE_READ)) {
96 file->f_mode |= FMODE_READ;
99 i_size = i_size_read(file_inode(file));
100 while (offset < i_size) {
103 rbuf_len = ima_kernel_read(file, offset, rbuf, PAGE_SIZE);
112 rc = crypto_shash_update(&desc.shash, rbuf, rbuf_len);
118 rc = crypto_shash_final(&desc.shash, digest);
120 file->f_mode &= ~FMODE_READ;
126 * Calculate the hash of a given buffer
128 int ima_calc_buffer_hash(const void *data, int len, char *digest)
131 struct shash_desc shash;
132 char ctx[crypto_shash_descsize(ima_shash_tfm)];
135 desc.shash.tfm = ima_shash_tfm;
136 desc.shash.flags = 0;
138 return crypto_shash_digest(&desc.shash, data, len, digest);
141 static void __init ima_pcrread(int idx, u8 *pcr)
146 if (tpm_pcr_read(TPM_ANY_NUM, idx, pcr) != 0)
147 pr_err("IMA: Error Communicating to TPM chip\n");
151 * Calculate the boot aggregate hash
153 int __init ima_calc_boot_aggregate(char *digest)
155 u8 pcr_i[IMA_DIGEST_SIZE];
158 struct shash_desc shash;
159 char ctx[crypto_shash_descsize(ima_shash_tfm)];
162 desc.shash.tfm = ima_shash_tfm;
163 desc.shash.flags = 0;
165 rc = crypto_shash_init(&desc.shash);
169 /* cumulative sha1 over tpm registers 0-7 */
170 for (i = TPM_PCR0; i < TPM_PCR8; i++) {
171 ima_pcrread(i, pcr_i);
172 /* now accumulate with current aggregate */
173 rc = crypto_shash_update(&desc.shash, pcr_i, IMA_DIGEST_SIZE);
176 crypto_shash_final(&desc.shash, digest);