diff options
Diffstat (limited to 'security/integrity/ima/ima_crypto.c')
| -rw-r--r-- | security/integrity/ima/ima_crypto.c | 300 |
1 files changed, 300 insertions, 0 deletions
diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c new file mode 100644 index 00000000000..ccd0ac8fa9a --- /dev/null +++ b/security/integrity/ima/ima_crypto.c @@ -0,0 +1,300 @@ +/* + * 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 + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#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 <crypto/hash.h> +#include <crypto/hash_info.h> +#include "ima.h" + +static struct crypto_shash *ima_shash_tfm; + +/** + * ima_kernel_read - read file content + * + * This is a function for reading file content instead of kernel_read(). + * It does not perform locking checks to ensure it cannot be blocked. + * It does not perform security checks because it is irrelevant for IMA. + * + */ +static int ima_kernel_read(struct file *file, loff_t offset, + char *addr, unsigned long count) +{ + mm_segment_t old_fs; + char __user *buf = addr; + ssize_t ret; + + if (!(file->f_mode & FMODE_READ)) + return -EBADF; + if (!file->f_op->read && !file->f_op->aio_read) + return -EINVAL; + + old_fs = get_fs(); + set_fs(get_ds()); + if (file->f_op->read) + ret = file->f_op->read(file, buf, count, &offset); + else + ret = do_sync_read(file, buf, count, &offset); + set_fs(old_fs); + return ret; +} + +int ima_init_crypto(void) +{ + long rc; + + ima_shash_tfm = crypto_alloc_shash(hash_algo_name[ima_hash_algo], 0, 0); + if (IS_ERR(ima_shash_tfm)) { + rc = PTR_ERR(ima_shash_tfm); + pr_err("Can not allocate %s (reason: %ld)\n", + hash_algo_name[ima_hash_algo], rc); + return rc; + } + return 0; +} + +static struct crypto_shash *ima_alloc_tfm(enum hash_algo algo) +{ + struct crypto_shash *tfm = ima_shash_tfm; + int rc; + + if (algo != ima_hash_algo && algo < HASH_ALGO__LAST) { + tfm = crypto_alloc_shash(hash_algo_name[algo], 0, 0); + if (IS_ERR(tfm)) { + rc = PTR_ERR(tfm); + pr_err("Can not allocate %s (reason: %d)\n", + hash_algo_name[algo], rc); + } + } + return tfm; +} + +static void ima_free_tfm(struct crypto_shash *tfm) +{ + if (tfm != ima_shash_tfm) + crypto_free_shash(tfm); +} + +/* + * Calculate the MD5/SHA1 file digest + */ +static int ima_calc_file_hash_tfm(struct file *file, + struct ima_digest_data *hash, + struct crypto_shash *tfm) +{ + loff_t i_size, offset = 0; + char *rbuf; + int rc, read = 0; + struct { + struct shash_desc shash; + char ctx[crypto_shash_descsize(tfm)]; + } desc; + + desc.shash.tfm = tfm; + desc.shash.flags = 0; + + hash->length = crypto_shash_digestsize(tfm); + + rc = crypto_shash_init(&desc.shash); + if (rc != 0) + return rc; + + i_size = i_size_read(file_inode(file)); + + if (i_size == 0) + goto out; + + rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL); + if (!rbuf) + return -ENOMEM; + + if (!(file->f_mode & FMODE_READ)) { + file->f_mode |= FMODE_READ; + read = 1; + } + + while (offset < i_size) { + int rbuf_len; + + rbuf_len = ima_kernel_read(file, offset, rbuf, PAGE_SIZE); + if (rbuf_len < 0) { + rc = rbuf_len; + break; + } + if (rbuf_len == 0) + break; + offset += rbuf_len; + + rc = crypto_shash_update(&desc.shash, rbuf, rbuf_len); + if (rc) + break; + } + if (read) + file->f_mode &= ~FMODE_READ; + kfree(rbuf); +out: + if (!rc) + rc = crypto_shash_final(&desc.shash, hash->digest); + return rc; +} + +int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash) +{ + struct crypto_shash *tfm; + int rc; + + tfm = ima_alloc_tfm(hash->algo); + if (IS_ERR(tfm)) + return PTR_ERR(tfm); + + rc = ima_calc_file_hash_tfm(file, hash, tfm); + + ima_free_tfm(tfm); + + return rc; +} + +/* + * Calculate the hash of template data + */ +static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data, + struct ima_template_desc *td, + int num_fields, + struct ima_digest_data *hash, + struct crypto_shash *tfm) +{ + struct { + struct shash_desc shash; + char ctx[crypto_shash_descsize(tfm)]; + } desc; + int rc, i; + + desc.shash.tfm = tfm; + desc.shash.flags = 0; + + hash->length = crypto_shash_digestsize(tfm); + + rc = crypto_shash_init(&desc.shash); + if (rc != 0) + return rc; + + for (i = 0; i < num_fields; i++) { + u8 buffer[IMA_EVENT_NAME_LEN_MAX + 1] = { 0 }; + u8 *data_to_hash = field_data[i].data; + u32 datalen = field_data[i].len; + + if (strcmp(td->name, IMA_TEMPLATE_IMA_NAME) != 0) { + rc = crypto_shash_update(&desc.shash, + (const u8 *) &field_data[i].len, + sizeof(field_data[i].len)); + if (rc) + break; + } else if (strcmp(td->fields[i]->field_id, "n") == 0) { + memcpy(buffer, data_to_hash, datalen); + data_to_hash = buffer; + datalen = IMA_EVENT_NAME_LEN_MAX + 1; + } + rc = crypto_shash_update(&desc.shash, data_to_hash, datalen); + if (rc) + break; + } + + if (!rc) + rc = crypto_shash_final(&desc.shash, hash->digest); + + return rc; +} + +int ima_calc_field_array_hash(struct ima_field_data *field_data, + struct ima_template_desc *desc, int num_fields, + struct ima_digest_data *hash) +{ + struct crypto_shash *tfm; + int rc; + + tfm = ima_alloc_tfm(hash->algo); + if (IS_ERR(tfm)) + return PTR_ERR(tfm); + + rc = ima_calc_field_array_hash_tfm(field_data, desc, num_fields, + hash, tfm); + + ima_free_tfm(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 + */ +static int __init ima_calc_boot_aggregate_tfm(char *digest, + struct crypto_shash *tfm) +{ + u8 pcr_i[TPM_DIGEST_SIZE]; + int rc, i; + struct { + struct shash_desc shash; + char ctx[crypto_shash_descsize(tfm)]; + } desc; + + desc.shash.tfm = tfm; + desc.shash.flags = 0; + + rc = crypto_shash_init(&desc.shash); + 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 */ + rc = crypto_shash_update(&desc.shash, pcr_i, TPM_DIGEST_SIZE); + } + if (!rc) + crypto_shash_final(&desc.shash, digest); + return rc; +} + +int __init ima_calc_boot_aggregate(struct ima_digest_data *hash) +{ + struct crypto_shash *tfm; + int rc; + + tfm = ima_alloc_tfm(hash->algo); + if (IS_ERR(tfm)) + return PTR_ERR(tfm); + + hash->length = crypto_shash_digestsize(tfm); + rc = ima_calc_boot_aggregate_tfm(hash->digest, tfm); + + ima_free_tfm(tfm); + + return rc; +} |