text: /*
   * 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/slab.h>
  #include <linux/module.h>
  #include <linux/seq_file.h>
  #include <linux/rculist.h>
  #include <linux/rcupdate.h>
  #include <linux/parser.h>
  #include <linux/vmalloc.h>
  
  #include "ima.h"
  
  static DEFINE_MUTEX(ima_write_mutex);
  
  static int valid_policy = 1;
  
  static ssize_t ima_show_htable_value(char __user *buf, size_t count,
  				     loff_t *ppos, atomic_long_t *val)
  {
  	char tmpbuf[32];	/* greater than largest 'long' string value */
  	ssize_t len;
  
  	len = scnprintf(tmpbuf, sizeof(tmpbuf), "%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 const struct file_operations ima_htable_violations_ops = {
  	.read = ima_show_htable_violations,
  	.llseek = generic_file_llseek,
  };
  
  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 const struct file_operations ima_measurements_count_ops = {
  	.read = ima_show_measurements_count,
  	.llseek = generic_file_llseek,
  };
  
  /* 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(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)
  {
  }
  
  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 length]
   *       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;
  	char *template_name;
  	int namelen;
  	bool is_ima_template = false;
  	int i;
  
  	/* get entry */
  	e = qe->entry;
  	if (e == NULL)
  		return -1;
  
  	template_name = (e->template_desc->name[0] != '\0') ?
  	    e->template_desc->name : e->template_desc->fmt;
  
  	/*
  	 * 1st: PCRIndex
  	 * PCR used defaults to the same (config option) in
  	 * little-endian format, unless set in policy
  	 */
  	ima_putc(m, &e->pcr, sizeof(e->pcr));
  
  	/* 2nd: template digest */
  	ima_putc(m, e->digest, TPM_DIGEST_SIZE);
  
  	/* 3rd: template name size */
  	namelen = strlen(template_name);
  	ima_putc(m, &namelen, sizeof(namelen));
  
  	/* 4th:  template name */
  	ima_putc(m, template_name, namelen);
  
  	/* 5th:  template length (except for 'ima' template) */
  	if (strcmp(template_name, IMA_TEMPLATE_IMA_NAME) == 0)
  		is_ima_template = true;
  
  	if (!is_ima_template)
  		ima_putc(m, &e->template_data_len,
  			 sizeof(e->template_data_len));
  
  	/* 6th:  template specific data */
  	for (i = 0; i < e->template_desc->num_fields; i++) {
  		enum ima_show_type show = IMA_SHOW_BINARY;
  		struct ima_template_field *field = e->template_desc->fields[i];
  
  		if (is_ima_template && strcmp(field->field_id, "d") == 0)
  			show = IMA_SHOW_BINARY_NO_FIELD_LEN;
  		if (is_ima_template && strcmp(field->field_id, "n") == 0)
  			show = IMA_SHOW_BINARY_OLD_STRING_FMT;
  		field->field_show(m, show, &e->template_data[i]);
  	}
  	return 0;
  }
  
  static const 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 const struct file_operations ima_measurements_ops = {
  	.open = ima_measurements_open,
  	.read = seq_read,
  	.llseek = seq_lseek,
  	.release = seq_release,
  };
  
  void ima_print_digest(struct seq_file *m, u8 *digest, u32 size)
  {
  	u32 i;
  
  	for (i = 0; i < size; i++)
  		seq_printf(m, "%02x", *(digest + i));
  }
  
  /* 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;
  	char *template_name;
  	int i;
  
  	/* get entry */
  	e = qe->entry;
  	if (e == NULL)
  		return -1;
  
  	template_name = (e->template_desc->name[0] != '\0') ?
  	    e->template_desc->name : e->template_desc->fmt;
  
  	/* 1st: PCR used (config option) */
  	seq_printf(m, "%2d ", e->pcr);
  
  	/* 2nd: SHA1 template hash */
  	ima_print_digest(m, e->digest, TPM_DIGEST_SIZE);
  
  	/* 3th:  template name */
  	seq_printf(m, " %s", template_name);
  
  	/* 4th:  template specific data */
  	for (i = 0; i < e->template_desc->num_fields; i++) {
  		seq_puts(m, " ");
  		if (e->template_data[i].len == 0)
  			continue;
  
  		e->template_desc->fields[i]->field_show(m, IMA_SHOW_ASCII,
  							&e->template_data[i]);
  	}
  	seq_puts(m, "\n");
  	return 0;
  }
  
  static const 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 const 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_read_policy(char *path)
  {
  	void *data;
  	char *datap;
  	loff_t size;
  	int rc, pathlen = strlen(path);
  
  	char *p;
  
  	/* remove \n */
  	datap = path;
  	strsep(&datap, "\n");
  
  	rc = kernel_read_file_from_path(path, &data, &size, 0, READING_POLICY);
  	if (rc < 0) {
  		pr_err("Unable to open file: %s (%d)", path, rc);
  		return rc;
  	}
  
  	datap = data;
  	while (size > 0 && (p = strsep(&datap, "\n"))) {
  		pr_debug("rule: %s\n", p);
  		rc = ima_parse_add_rule(p);
  		if (rc < 0)
  			break;
  		size -= rc;
  	}
  
  	vfree(data);
  	if (rc < 0)
  		return rc;
  	else if (size)
  		return -EINVAL;
  	else
  		return pathlen;
  }
  
  static ssize_t ima_write_policy(struct file *file, const char __user *buf,
  				size_t datalen, loff_t *ppos)
  {
  	char *data;
  	ssize_t result;
  
  	if (datalen >= PAGE_SIZE)
  		datalen = PAGE_SIZE - 1;
  
  	/* No partial writes. */
  	result = -EINVAL;
  	if (*ppos != 0)
  		goto out;
  
  	result = -ENOMEM;
  	data = kmalloc(datalen + 1, GFP_KERNEL);
  	if (!data)
  		goto out;
  
  	*(data + datalen) = '\0';
  
  	result = -EFAULT;
  	if (copy_from_user(data, buf, datalen))
  		goto out_free;
  
  	result = mutex_lock_interruptible(&ima_write_mutex);
  	if (result < 0)
  		goto out_free;
  
  	if (data[0] == '/') {
  		result = ima_read_policy(data);
  	} else if (ima_appraise & IMA_APPRAISE_POLICY) {
  		pr_err("IMA: signed policy file (specified as an absolute pathname) required\n");
  		integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL,
  				    "policy_update", "signed policy required",
  				    1, 0);
  		if (ima_appraise & IMA_APPRAISE_ENFORCE)
  			result = -EACCES;
  	} else {
  		result = ima_parse_add_rule(data);
  	}
  	mutex_unlock(&ima_write_mutex);
  out_free:
  	kfree(data);
  out:
  	if (result < 0)
  		valid_policy = 0;
  
  	return result;
  }
  
  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;
  
  enum ima_fs_flags {
  	IMA_FS_BUSY,
  };
  
  static unsigned long ima_fs_flags;
  
  #ifdef	CONFIG_IMA_READ_POLICY
  static const struct seq_operations ima_policy_seqops = {
  		.start = ima_policy_start,
  		.next = ima_policy_next,
  		.stop = ima_policy_stop,
  		.show = ima_policy_show,
  };
  #endif
  
  /*
   * ima_open_policy: sequentialize access to the policy file
   */
  static int ima_open_policy(struct inode *inode, struct file *filp)
  {
  	if (!(filp->f_flags & O_WRONLY)) {
  #ifndef	CONFIG_IMA_READ_POLICY
  		return -EACCES;
  #else
  		if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
  			return -EACCES;
  		if (!capable(CAP_SYS_ADMIN))
  			return -EPERM;
  		return seq_open(filp, &ima_policy_seqops);
  #endif
  	}
  	if (test_and_set_bit(IMA_FS_BUSY, &ima_fs_flags))
  		return -EBUSY;
  	return 0;
  }
  
  /*
   * 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)
  {
  	const char *cause = valid_policy ? "completed" : "failed";
  
  	if ((file->f_flags & O_ACCMODE) == O_RDONLY)
  		return seq_release(inode, file);
  
  	if (valid_policy && ima_check_policy() < 0) {
  		cause = "failed";
  		valid_policy = 0;
  	}
  
  	pr_info("IMA: policy update %s\n", cause);
  	integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL,
  			    "policy_update", cause, !valid_policy, 0);
  
  	if (!valid_policy) {
  		ima_delete_rules();
  		valid_policy = 1;
  		clear_bit(IMA_FS_BUSY, &ima_fs_flags);
  		return 0;
  	}
  
  	ima_update_policy();
  #ifndef	CONFIG_IMA_WRITE_POLICY
  	securityfs_remove(ima_policy);
  	ima_policy = NULL;
  #else
  	clear_bit(IMA_FS_BUSY, &ima_fs_flags);
  #endif
  	return 0;
  }
  
  static const struct file_operations ima_measure_policy_ops = {
  	.open = ima_open_policy,
  	.write = ima_write_policy,
  	.read = seq_read,
  	.release = ima_release_policy,
  	.llseek = generic_file_llseek,
  };
  
  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", POLICY_FILE_FLAGS,
  					    ima_dir, NULL,
  					    &ima_measure_policy_ops);
  	if (IS_ERR(ima_policy))
  		goto out;
  
  	return 0;
  out:
  	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);
  	return -1;
  }
  