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integrity: define a new function integrity_read_file()

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This patch defines a new function called integrity_read_file()
to read file from the kernel into a buffer. Subsequent patches
will read a file containing the public keys and load them onto
the IMA keyring.

This patch moves and renames ima_kernel_read(), the non-security
checking version of kernel_read(), to integrity_kernel_read().

Changes in v3:
* Patch descriptions improved (Mimi)
* Add missing cast (kbuild test robot)

Changes in v2:
* configuration option removed
* function declared as '__init'

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
This commit is contained in:
Dmitry Kasatkin 2014-11-05 17:01:12 +02:00 committed by Mimi Zohar
parent c2426d2ad5
commit e3c4abbfa9
3 changed files with 85 additions and 32 deletions
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78
security/integrity/iint.c
View File

@ -19,6 +19,8 @@
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/rbtree.h>
#include <linux/file.h>
#include <linux/uaccess.h>
#include "integrity.h"
static struct rb_root integrity_iint_tree = RB_ROOT;
@ -167,3 +169,79 @@ static int __init integrity_iintcache_init(void)
return 0;
}
security_initcall(integrity_iintcache_init);
/*
* integrity_kernel_read - read data from the file
*
* 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.
*
*/
int integrity_kernel_read(struct file *file, loff_t offset,
char *addr, unsigned long count)
{
mm_segment_t old_fs;
char __user *buf = (char __user *)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;
}
/*
* integrity_read_file - read entire file content into the buffer
*
* This is function opens a file, allocates the buffer of required
* size, read entire file content to the buffer and closes the file
*
* It is used only by init code.
*
*/
int __init integrity_read_file(const char *path, char **data)
{
struct file *file;
loff_t size;
char *buf;
int rc = -EINVAL;
file = filp_open(path, O_RDONLY, 0);
if (IS_ERR(file)) {
rc = PTR_ERR(file);
pr_err("Unable to open file: %s (%d)", path, rc);
return rc;
}
size = i_size_read(file_inode(file));
if (size <= 0)
goto out;
buf = kmalloc(size, GFP_KERNEL);
if (!buf) {
rc = -ENOMEM;
goto out;
}
rc = integrity_kernel_read(file, 0, buf, size);
if (rc < 0)
kfree(buf);
else if (rc != size)
rc = -EIO;
else
*data = buf;
out:
fput(file);
return rc;
}

35
security/integrity/ima/ima_crypto.c
View File

@ -67,36 +67,6 @@ 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;
@ -324,7 +294,8 @@ static int ima_calc_file_hash_atfm(struct file *file,
}
/* read buffer */
rbuf_len = min_t(loff_t, i_size - offset, rbuf_size[active]);
rc = ima_kernel_read(file, offset, rbuf[active], rbuf_len);
rc = integrity_kernel_read(file, offset, rbuf[active],
rbuf_len);
if (rc != rbuf_len)
goto out3;
@ -417,7 +388,7 @@ static int ima_calc_file_hash_tfm(struct file *file,
while (offset < i_size) {
int rbuf_len;
rbuf_len = ima_kernel_read(file, offset, rbuf, PAGE_SIZE);
rbuf_len = integrity_kernel_read(file, offset, rbuf, PAGE_SIZE);
if (rbuf_len < 0) {
rc = rbuf_len;
break;

4
security/integrity/integrity.h
View File

@ -119,6 +119,10 @@ struct integrity_iint_cache {
*/
struct integrity_iint_cache *integrity_iint_find(struct inode *inode);
int integrity_kernel_read(struct file *file, loff_t offset,
char *addr, unsigned long count);
int __init integrity_read_file(const char *path, char **data);
#define INTEGRITY_KEYRING_EVM 0
#define INTEGRITY_KEYRING_MODULE 1
#define INTEGRITY_KEYRING_IMA 2