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