- 根目录:
- security
- integrity
- ima
- ima_crypto.c
/*
* 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/moduleparam.h>
#include <linux/ratelimit.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"
struct ahash_completion {
struct completion completion;
int err;
};
/* minimum file size for ahash use */
static unsigned long ima_ahash_minsize;
module_param_named(ahash_minsize, ima_ahash_minsize, ulong, 0644);
MODULE_PARM_DESC(ahash_minsize, "Minimum file size for ahash use");
/* default is 0 - 1 page. */
static int ima_maxorder;
static unsigned int ima_bufsize = PAGE_SIZE;
static int param_set_bufsize(const char *val, const struct kernel_param *kp)
{
unsigned long long size;
int order;
size = memparse(val, NULL);
order = get_order(size);
if (order >= MAX_ORDER)
return -EINVAL;
ima_maxorder = order;
ima_bufsize = PAGE_SIZE << order;
return 0;
}
static struct kernel_param_ops param_ops_bufsize = {
.set = param_set_bufsize,
.get = param_get_uint,
};
#define param_check_bufsize(name, p) __param_check(name, p, unsigned int)
module_param_named(ahash_bufsize, ima_bufsize, bufsize, 0644);
MODULE_PARM_DESC(ahash_bufsize, "Maximum ahash buffer size");
static struct crypto_shash *ima_shash_tfm;
static struct crypto_ahash *ima_ahash_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 = -EINVAL;
if (!(file->f_mode & FMODE_READ))
return -EBADF;
old_fs = get_fs();
set_fs(get_ds());
if (file->f_op->read)
ret = file->f_op->read(file, buf, count, &offset);
else if (file->f_op->aio_read)
ret = do_sync_read(file, buf, count, &offset);
else if (file->f_op->read_iter)
ret = new_sync_read(file, buf, count, &offset);
set_fs(old_fs);
return ret;
}
int __init 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 < 0 || algo >= HASH_ALGO__LAST)
algo = ima_hash_algo;
if (algo != ima_hash_algo) {
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);
}
/**
* ima_alloc_pages() - Allocate contiguous pages.
* @max_size: Maximum amount of memory to allocate.
* @allocated_size: Returned size of actual allocation.
* @last_warn: Should the min_size allocation warn or not.
*
* Tries to do opportunistic allocation for memory first trying to allocate
* max_size amount of memory and then splitting that until zero order is
* reached. Allocation is tried without generating allocation warnings unless
* last_warn is set. Last_warn set affects only last allocation of zero order.
*
* By default, ima_maxorder is 0 and it is equivalent to kmalloc(GFP_KERNEL)
*
* Return pointer to allocated memory, or NULL on failure.
*/
static void *ima_alloc_pages(loff_t max_size, size_t *allocated_size,
int last_warn)
{
void *ptr;
int order = ima_maxorder;
gfp_t gfp_mask = __GFP_WAIT | __GFP_NOWARN | __GFP_NORETRY;
if (order)
order = min(get_order(max_size), order);
for (; order; order--) {
ptr = (void *)__get_free_pages(gfp_mask, order);
if (ptr) {
*allocated_size = PAGE_SIZE << order;
return ptr;
}
}
/* order is zero - one page */
gfp_mask = GFP_KERNEL;
if (!last_warn)
gfp_mask |= __GFP_NOWARN;
ptr = (void *)__get_free_pages(gfp_mask, 0);
if (ptr) {
*allocated_size = PAGE_SIZE;
return ptr;
}
*allocated_size = 0;
return NULL;
}
/**
* ima_free_pages() - Free pages allocated by ima_alloc_pages().
* @ptr: Pointer to allocated pages.
* @size: Size of allocated buffer.
*/
static void ima_free_pages(void *ptr, size_t size)
{
if (!ptr)
return;
free_pages((unsigned long)ptr, get_order(size));
}
static struct crypto_ahash *ima_alloc_atfm(enum hash_algo algo)
{
struct crypto_ahash *tfm = ima_ahash_tfm;
int rc;
if (algo < 0 || algo >= HASH_ALGO__LAST)
algo = ima_hash_algo;
if (algo != ima_hash_algo || !tfm) {
tfm = crypto_alloc_ahash(hash_algo_name[algo], 0, 0);
if (!IS_ERR(tfm)) {
if (algo == ima_hash_algo)
ima_ahash_tfm = tfm;
} else {
rc = PTR_ERR(tfm);
pr_err("Can not allocate %s (reason: %d)\n",
hash_algo_name[algo], rc);
}
}
return tfm;
}
static void ima_free_atfm(struct crypto_ahash *tfm)
{
if (tfm != ima_ahash_tfm)
crypto_free_ahash(tfm);
}
static void ahash_complete(struct crypto_async_request *req, int err)
{
struct ahash_completion *res = req->data;
if (err == -EINPROGRESS)
return;
res->err = err;
complete(&res->completion);
}
static int ahash_wait(int err, struct ahash_completion *res)
{
switch (err) {
case 0:
break;
case -EINPROGRESS:
case -EBUSY:
wait_for_completion(&res->completion);
reinit_completion(&res->completion);
err = res->err;
/* fall through */
default:
pr_crit_ratelimited("ahash calculation failed: err: %d\n", err);
}
return err;
}
static int ima_calc_file_hash_atfm(struct file *file,
struct ima_digest_data *hash,
struct crypto_ahash *tfm)
{
loff_t i_size, offset;
char *rbuf[2] = { NULL, };
int rc, read = 0, rbuf_len, active = 0, ahash_rc = 0;
struct ahash_request *req;
struct scatterlist sg[1];
struct ahash_completion res;
size_t rbuf_size[2];
hash->length = crypto_ahash_digestsize(tfm);
req = ahash_request_alloc(tfm, GFP_KERNEL);
if (!req)
return -ENOMEM;
init_completion(&res.completion);
ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
CRYPTO_TFM_REQ_MAY_SLEEP,
ahash_complete, &res);
rc = ahash_wait(crypto_ahash_init(req), &res);
if (rc)
goto out1;
i_size = i_size_read(file_inode(file));
if (i_size == 0)
goto out2;
/*
* Try to allocate maximum size of memory.
* Fail if even a single page cannot be allocated.
*/
rbuf[0] = ima_alloc_pages(i_size, &rbuf_size[0], 1);
if (!rbuf[0]) {
rc = -ENOMEM;
goto out1;
}
/* Only allocate one buffer if that is enough. */
if (i_size > rbuf_size[0]) {
/*
* Try to allocate secondary buffer. If that fails fallback to
* using single buffering. Use previous memory allocation size
* as baseline for possible allocation size.
*/
rbuf[1] = ima_alloc_pages(i_size - rbuf_size[0],
&rbuf_size[1], 0);
}
if (!(file->f_mode & FMODE_READ)) {
file->f_mode |= FMODE_READ;
read = 1;
}
for (offset = 0; offset < i_size; offset += rbuf_len) {
if (!rbuf[1] && offset) {
/* Not using two buffers, and it is not the first
* read/request, wait for the completion of the
* previous ahash_update() request.
*/
rc = ahash_wait(ahash_rc, &res);
if (rc)
goto out3;
}
/* read buffer */
rbuf_len = min_t(loff_t, i_size - offset, rbuf_size[active]);
rc = ima_kernel_read(file, offset, rbuf[active], rbuf_len);
if (rc != rbuf_len)
goto out3;
if (rbuf[1] && offset) {
/* Using two buffers, and it is not the first
* read/request, wait for the completion of the
* previous ahash_update() request.
*/
rc = ahash_wait(ahash_rc, &res);
if (rc)
goto out3;
}
sg_init_one(&sg[0], rbuf[active], rbuf_len);
ahash_request_set_crypt(req, sg, NULL, rbuf_len);
ahash_rc = crypto_ahash_update(req);
if (rbuf[1])
active = !active; /* swap buffers, if we use two */
}
/* wait for the last update request to complete */
rc = ahash_wait(ahash_rc, &res);
out3:
if (read)
file->f_mode &= ~FMODE_READ;
ima_free_pages(rbuf[0], rbuf_size[0]);
ima_free_pages(rbuf[1], rbuf_size[1]);
out2:
if (!rc) {
ahash_request_set_crypt(req, NULL, hash->digest, 0);
rc = ahash_wait(crypto_ahash_final(req), &res);
}
out1:
ahash_request_free(req);
return rc;
}
static int ima_calc_file_ahash(struct file *file, struct ima_digest_data *hash)
{
struct crypto_ahash *tfm;
int rc;
tfm = ima_alloc_atfm(hash->algo);
if (IS_ERR(tfm))
return PTR_ERR(tfm);
rc = ima_calc_file_hash_atfm(file, hash, tfm);
ima_free_atfm(tfm);
return rc;
}
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;
SHASH_DESC_ON_STACK(shash, tfm);
shash->tfm = tfm;
shash->flags = 0;
hash->length = crypto_shash_digestsize(tfm);
rc = crypto_shash_init(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(shash, rbuf, rbuf_len);
if (rc)
break;
}
if (read)
file->f_mode &= ~FMODE_READ;
kfree(rbuf);
out:
if (!rc)
rc = crypto_shash_final(shash, hash->digest);
return rc;
}
static int ima_calc_file_shash(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;
}
/*
* ima_calc_file_hash - calculate file hash
*
* Asynchronous hash (ahash) allows using HW acceleration for calculating
* a hash. ahash performance varies for different data sizes on different
* crypto accelerators. shash performance might be better for smaller files.
* The 'ima.ahash_minsize' module parameter allows specifying the best
* minimum file size for using ahash on the system.
*
* If the ima.ahash_minsize parameter is not specified, this function uses
* shash for the hash calculation. If ahash fails, it falls back to using
* shash.
*/
int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
{
loff_t i_size;
int rc;
i_size = i_size_read(file_inode(file));
if (ima_ahash_minsize && i_size >= ima_ahash_minsize) {
rc = ima_calc_file_ahash(file, hash);
if (!rc)
return 0;
}
return ima_calc_file_shash(file, hash);
}
/*
* 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)
{
SHASH_DESC_ON_STACK(shash, tfm);
int rc, i;
shash->tfm = tfm;
shash->flags = 0;
hash->length = crypto_shash_digestsize(tfm);
rc = crypto_shash_init(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(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(shash, data_to_hash, datalen);
if (rc)
break;
}
if (!rc)
rc = crypto_shash_final(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;
SHASH_DESC_ON_STACK(shash, tfm);
shash->tfm = tfm;
shash->flags = 0;
rc = crypto_shash_init(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(shash, pcr_i, TPM_DIGEST_SIZE);
}
if (!rc)
crypto_shash_final(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;
}