/*
* Copyright (C) 2005,2006,2007,2008 IBM Corporation
*
* Authors:
* Kylene Hall <kjhall@us.ibm.com>
* Reiner Sailer <sailer@us.ibm.com>
* Mimi Zohar <zohar@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_fs.c
* implemenents security file system for reporting
* current measurement list and IMA statistics
*/
#include <linux/fcntl.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/rculist.h>
#include <linux/rcupdate.h>
#include <linux/parser.h>
#include "ima.h"
static int valid_policy = 1;
#define TMPBUFLEN 12
static ssize_t ima_show_htable_value(char __user *buf, size_t count,
loff_t *ppos, atomic_long_t *val)
{
char tmpbuf[TMPBUFLEN];
ssize_t len;
len = scnprintf(tmpbuf, TMPBUFLEN, "%li\n", atomic_long_read(val));
return simple_read_from_buffer(buf, count, ppos, tmpbuf, len);
}
static ssize_t ima_show_htable_violations(struct file *filp,
char __user *buf,
size_t count, loff_t *ppos)
{
return ima_show_htable_value(buf, count, ppos, &ima_htable.violations);
}
static struct file_operations ima_htable_violations_ops = {
.read = ima_show_htable_violations
};
static ssize_t ima_show_measurements_count(struct file *filp,
char __user *buf,
size_t count, loff_t *ppos)
{
return ima_show_htable_value(buf, count, ppos, &ima_htable.len);
}
static struct file_operations ima_measurements_count_ops = {
.read = ima_show_measurements_count
};
/* returns pointer to hlist_node */
static void *ima_measurements_start(struct seq_file *m, loff_t *pos)
{
loff_t l = *pos;
struct ima_queue_entry *qe;
/* we need a lock since pos could point beyond last element */
rcu_read_lock();
list_for_each_entry_rcu(qe, &ima_measurements, later) {
if (!l--) {
rcu_read_unlock();
return qe;
}
}
rcu_read_unlock();
return NULL;
}
static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *pos)
{
struct ima_queue_entry *qe = v;
/* lock protects when reading beyond last element
* against concurrent list-extension
*/
rcu_read_lock();
qe = list_entry(rcu_dereference(qe->later.next),
struct ima_queue_entry, later);
rcu_read_unlock();
(*pos)++;
return (&qe->later == &ima_measurements) ? NULL : qe;
}
static void ima_measurements_stop(struct seq_file *m, void *v)
{
}
static void ima_putc(struct seq_file *m, void *data, int datalen)
{
while (datalen--)
seq_putc(m, *(char *)data++);
}
/* print format:
* 32bit-le=pcr#
* char[20]=template digest
* 32bit-le=template name size
* char[n]=template name
* eventdata[n]=template specific data
*/
static int ima_measurements_show(struct seq_file *m, void *v)
{
/* the list never shrinks, so we don't need a lock here */
struct ima_queue_entry *qe = v;
struct ima_template_entry *e;
int namelen;
u32 pcr = CONFIG_IMA_MEASURE_PCR_IDX;
/* get entry */
e = qe->entry;
if (e == NULL)
return -1;
/*
* 1st: PCRIndex
* PCR used is always the same (config option) in
* little-endian format
*/
ima_putc(m, &pcr, sizeof pcr);
/* 2nd: template digest */
ima_putc(m, e->digest, IMA_DIGEST_SIZE);
/* 3rd: template name size */
namelen = strlen(e->template_name);
ima_putc(m, &namelen, sizeof namelen);
/* 4th: template name */
ima_putc(m, (void *)e->template_name, namelen);
/* 5th: template specific data */
ima_template_show(m, (struct ima_template_data *)&e->template,
IMA_SHOW_BINARY);
return 0;
}
static struct seq_operations ima_measurments_seqops = {
.start = ima_measurements_start,
.next = ima_measurements_next,
.stop = ima_measurements_stop,
.show = ima_measurements_show
};
static int ima_measurements_open(struct inode *inode, struct file *file)
{
return seq_open(file, &ima_measurments_seqops);
}
static struct file_operations ima_measurements_ops = {
.open = ima_measurements_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
static void ima_print_digest(struct seq_file *m, u8 *digest)
{
int i;
for (i = 0; i < IMA_DIGEST_SIZE; i++)
seq_printf(m, "%02x", *(digest + i));
}
void ima_template_show(struct seq_file *m, void *e, enum ima_show_type show)
{
struct ima_template_data *entry = e;
int namelen;
switch (show) {
case IMA_SHOW_ASCII:
ima_print_digest(m, entry->digest);
seq_printf(m, " %s\n", entry->file_name);
break;
case IMA_SHOW_BINARY:
ima_putc(m, entry->digest, IMA_DIGEST_SIZE);
namelen = strlen(entry->file_name);
ima_putc(m, &namelen, sizeof namelen);
ima_putc(m, entry->file_name, namelen);
default:
break;
}
}
/* print in ascii */
static int ima_ascii_measurements_show(struct seq_file *m, void *v)
{
/* the list never shrinks, so we don't need a lock here */
struct ima_queue_entry *qe = v;
struct ima_template_entry *e;
/* get entry */
e = qe->entry;
if (e == NULL)
return -1;
/* 1st: PCR used (config option) */
seq_printf(m, "%2d ", CONFIG_IMA_MEASURE_PCR_IDX);
/* 2nd: SHA1 template hash */
ima_print_digest(m, e->digest);
/* 3th: template name */
seq_printf(m, " %s ", e->template_name);
/* 4th: template specific data */
ima_template_show(m, (struct ima_template_data *)&e->template,
IMA_SHOW_ASCII);
return 0;
}
static struct seq_operations ima_ascii_measurements_seqops = {
.start = ima_measurements_start,
.next = ima_measurements_next,
.stop = ima_measurements_stop,
.show = ima_ascii_measurements_show
};
static int ima_ascii_measurements_open(struct inode *inode, struct file *file)
{
return seq_open(file, &ima_ascii_measurements_seqops);
}
static struct file_operations ima_ascii_measurements_ops = {
.open = ima_ascii_measurements_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
static ssize_t ima_write_policy(struct file *file, const char __user *buf,
size_t datalen, loff_t *ppos)
{
char *data;
int rc;
if (datalen >= PAGE_SIZE)
return -ENOMEM;
if (*ppos != 0) {
/* No partial writes. */
return -EINVAL;
}
data = kmalloc(datalen + 1, GFP_KERNEL);
if (!data)
return -ENOMEM;
if (copy_from_user(data, buf, datalen)) {
kfree(data);
return -EFAULT;
}
*(data + datalen) = '\0';
rc = ima_parse_add_rule(data);
if (rc < 0) {
datalen = -EINVAL;
valid_policy = 0;
}
kfree(data);
return datalen;
}
static struct dentry *ima_dir;
static struct dentry *binary_runtime_measurements;
static struct dentry *ascii_runtime_measurements;
static struct dentry *runtime_measurements_count;
static struct dentry *violations;
static struct dentry *ima_policy;
static atomic_t policy_opencount = ATOMIC_INIT(1);
/*
* ima_open_policy: sequentialize access to the policy file
*/
int ima_open_policy(struct inode * inode, struct file * filp)
{
/* No point in being allowed to open it if you aren't going to write */
if (!(filp->f_flags & O_WRONLY))
return -EACCES;
if (atomic_dec_and_test(&policy_opencount))
return 0;
return -EBUSY;
}
/*
* ima_release_policy - start using the new measure policy rules.
*
* Initially, ima_measure points to the default policy rules, now
* point to the new policy rules, and remove the securityfs policy file,
* assuming a valid policy.
*/
static int ima_release_policy(struct inode *inode, struct file *file)
{
if (!valid_policy) {
ima_delete_rules();
valid_policy = 1;
atomic_set(&policy_opencount, 1);
return 0;
}
ima_update_policy();
securityfs_remove(ima_policy);
ima_policy = NULL;
return 0;
}
static struct file_operations ima_measure_policy_ops = {
.open = ima_open_policy,
.write = ima_write_policy,
.release = ima_release_policy
};
int __init ima_fs_init(void)
{
ima_dir = securityfs_create_dir("ima", NULL);
if (IS_ERR(ima_dir))
return -1;
binary_runtime_measurements =
securityfs_create_file("binary_runtime_measurements",
S_IRUSR | S_IRGRP, ima_dir, NULL,
&ima_measurements_ops);
if (IS_ERR(binary_runtime_measurements))
goto out;
ascii_runtime_measurements =
securityfs_create_file("ascii_runtime_measurements",
S_IRUSR | S_IRGRP, ima_dir, NULL,
&ima_ascii_measurements_ops);
if (IS_ERR(ascii_runtime_measurements))
goto out;
runtime_measurements_count =
securityfs_create_file("runtime_measurements_count",
S_IRUSR | S_IRGRP, ima_dir, NULL,
&ima_measurements_count_ops);
if (IS_ERR(runtime_measurements_count))
goto out;
violations =
securityfs_create_file("violations", S_IRUSR | S_IRGRP,
ima_dir, NULL, &ima_htable_violations_ops);
if (IS_ERR(violations))
goto out;
ima_policy = securityfs_create_file("policy",
S_IWUSR,
ima_dir, NULL,
&ima_measure_policy_ops);
if (IS_ERR(ima_policy))
goto out;
return 0;
out:
securityfs_remove(runtime_measurements_count);
securityfs_remove(ascii_runtime_measurements);
securityfs_remove(binary_runtime_measurements);
securityfs_remove(ima_dir);
securityfs_remove(ima_policy);
return -1;
}
void __exit ima_fs_cleanup(void)
{
securityfs_remove(violations);
securityfs_remove(runtime_measurements_count);
securityfs_remove(ascii_runtime_measurements);
securityfs_remove(binary_runtime_measurements);
securityfs_remove(ima_dir);
securityfs_remove(ima_policy);
}
