[deliverable/linux.git] / security / integrity / ima / ima_api.c

/*
 * Copyright (C) 2008 IBM Corporation
 *
 * Author: 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_api.c
 *	Implements must_appraise_or_measure, collect_measurement,
 *	appraise_measurement, store_measurement and store_template.
 */
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/xattr.h>
#include <linux/evm.h>
#include <crypto/hash_info.h>
#include "ima.h"

/*
 * ima_alloc_init_template - create and initialize a new template entry
 */
int ima_alloc_init_template(struct integrity_iint_cache *iint,
			    struct file *file, const unsigned char *filename,
			    struct ima_template_entry **entry)
{
	struct ima_template_desc *template_desc = ima_template_desc_current();
	int i, result = 0;

	*entry = kzalloc(sizeof(**entry) + template_desc->num_fields *
			 sizeof(struct ima_field_data), GFP_NOFS);
	if (!*entry)
		return -ENOMEM;

	for (i = 0; i < template_desc->num_fields; i++) {
		struct ima_template_field *field = template_desc->fields[i];
		u32 len;

		result = field->field_init(iint, file, filename,
					   &((*entry)->template_data[i]));
		if (result != 0)
			goto out;

		len = (*entry)->template_data[i].len;
		(*entry)->template_data_len += sizeof(len);
		(*entry)->template_data_len += len;
	}
	(*entry)->template_desc = template_desc;
	return 0;
out:
	kfree(*entry);
	*entry = NULL;
	return result;
}

/*
 * ima_store_template - store ima template measurements
 *
 * Calculate the hash of a template entry, add the template entry
 * to an ordered list of measurement entries maintained inside the kernel,
 * and also update the aggregate integrity value (maintained inside the
 * configured TPM PCR) over the hashes of the current list of measurement
 * entries.
 *
 * Applications retrieve the current kernel-held measurement list through
 * the securityfs entries in /sys/kernel/security/ima. The signed aggregate
 * TPM PCR (called quote) can be retrieved using a TPM user space library
 * and is used to validate the measurement list.
 *
 * Returns 0 on success, error code otherwise
 */
int ima_store_template(struct ima_template_entry *entry,
		       int violation, struct inode *inode,
		       const unsigned char *filename)
{
	const char *op = "add_template_measure";
	const char *audit_cause = "hashing_error";
	char *template_name = entry->template_desc->name;
	int result;
	struct {
		struct ima_digest_data hdr;
		char digest[TPM_DIGEST_SIZE];
	} hash;

	if (!violation) {
		int num_fields = entry->template_desc->num_fields;

		/* this function uses default algo */
		hash.hdr.algo = HASH_ALGO_SHA1;
		result = ima_calc_field_array_hash(&entry->template_data[0],
						   num_fields, &hash.hdr);
		if (result < 0) {
			integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
					    template_name, op,
					    audit_cause, result, 0);
			return result;
		}
		memcpy(entry->digest, hash.hdr.digest, hash.hdr.length);
	}
	result = ima_add_template_entry(entry, violation, op, inode, filename);
	return result;
}

/*
 * ima_add_violation - add violation to measurement list.
 *
 * Violations are flagged in the measurement list with zero hash values.
 * By extending the PCR with 0xFF's instead of with zeroes, the PCR
 * value is invalidated.
 */
void ima_add_violation(struct file *file, const unsigned char *filename,
		       const char *op, const char *cause)
{
	struct ima_template_entry *entry;
	struct inode *inode = file->f_dentry->d_inode;
	int violation = 1;
	int result;

	/* can overflow, only indicator */
	atomic_long_inc(&ima_htable.violations);

	result = ima_alloc_init_template(NULL, file, filename, &entry);
	if (result < 0) {
		result = -ENOMEM;
		goto err_out;
	}
	result = ima_store_template(entry, violation, inode, filename);
	if (result < 0)
		kfree(entry);
err_out:
	integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
			    op, cause, result, 0);
}

/**
 * ima_get_action - appraise & measure decision based on policy.
 * @inode: pointer to inode to measure
 * @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXECUTE)
 * @function: calling function (FILE_CHECK, BPRM_CHECK, MMAP_CHECK, MODULE_CHECK)
 *
 * The policy is defined in terms of keypairs:
 * 		subj=, obj=, type=, func=, mask=, fsmagic=
 *	subj,obj, and type: are LSM specific.
 * 	func: FILE_CHECK | BPRM_CHECK | MMAP_CHECK | MODULE_CHECK
 * 	mask: contains the permission mask
 *	fsmagic: hex value
 *
 * Returns IMA_MEASURE, IMA_APPRAISE mask.
 *
 */
int ima_get_action(struct inode *inode, int mask, int function)
{
	int flags = IMA_MEASURE | IMA_AUDIT | IMA_APPRAISE;

	if (!ima_appraise)
		flags &= ~IMA_APPRAISE;

	return ima_match_policy(inode, function, mask, flags);
}

int ima_must_measure(struct inode *inode, int mask, int function)
{
	return ima_match_policy(inode, function, mask, IMA_MEASURE);
}

/*
 * ima_collect_measurement - collect file measurement
 *
 * Calculate the file hash, if it doesn't already exist,
 * storing the measurement and i_version in the iint.
 *
 * Must be called with iint->mutex held.
 *
 * Return 0 on success, error code otherwise
 */
int ima_collect_measurement(struct integrity_iint_cache *iint,
			    struct file *file,
			    struct evm_ima_xattr_data **xattr_value,
			    int *xattr_len)
{
	struct inode *inode = file_inode(file);
	const char *filename = file->f_dentry->d_name.name;
	int result = 0;
	struct {
		struct ima_digest_data hdr;
		char digest[IMA_MAX_DIGEST_SIZE];
	} hash;

	if (xattr_value)
		*xattr_len = ima_read_xattr(file->f_dentry, xattr_value);

	if (!(iint->flags & IMA_COLLECTED)) {
		u64 i_version = file_inode(file)->i_version;

		/* use default hash algorithm */
		hash.hdr.algo = ima_hash_algo;

		if (xattr_value)
			ima_get_hash_algo(*xattr_value, *xattr_len, &hash.hdr);

		result = ima_calc_file_hash(file, &hash.hdr);
		if (!result) {
			int length = sizeof(hash.hdr) + hash.hdr.length;
			void *tmpbuf = krealloc(iint->ima_hash, length,
						GFP_NOFS);
			if (tmpbuf) {
				iint->ima_hash = tmpbuf;
				memcpy(iint->ima_hash, &hash, length);
				iint->version = i_version;
				iint->flags |= IMA_COLLECTED;
			} else
				result = -ENOMEM;
		}
	}
	if (result)
		integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
				    filename, "collect_data", "failed",
				    result, 0);
	return result;
}

/*
 * ima_store_measurement - store file measurement
 *
 * Create an "ima" template and then store the template by calling
 * ima_store_template.
 *
 * We only get here if the inode has not already been measured,
 * but the measurement could already exist:
 * 	- multiple copies of the same file on either the same or
 *	  different filesystems.
 *	- the inode was previously flushed as well as the iint info,
 *	  containing the hashing info.
 *
 * Must be called with iint->mutex held.
 */
void ima_store_measurement(struct integrity_iint_cache *iint,
			   struct file *file, const unsigned char *filename)
{
	const char *op = "add_template_measure";
	const char *audit_cause = "ENOMEM";
	int result = -ENOMEM;
	struct inode *inode = file_inode(file);
	struct ima_template_entry *entry;
	int violation = 0;

	if (iint->flags & IMA_MEASURED)
		return;

	result = ima_alloc_init_template(iint, file, filename, &entry);
	if (result < 0) {
		integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
				    op, audit_cause, result, 0);
		return;
	}

	result = ima_store_template(entry, violation, inode, filename);
	if (!result || result == -EEXIST)
		iint->flags |= IMA_MEASURED;
	if (result < 0)
		kfree(entry);
}

void ima_audit_measurement(struct integrity_iint_cache *iint,
			   const unsigned char *filename)
{
	struct audit_buffer *ab;
	char hash[(iint->ima_hash->length * 2) + 1];
	int i;

	if (iint->flags & IMA_AUDITED)
		return;

	for (i = 0; i < iint->ima_hash->length; i++)
		hex_byte_pack(hash + (i * 2), iint->ima_hash->digest[i]);
	hash[i * 2] = '\0';

	ab = audit_log_start(current->audit_context, GFP_KERNEL,
			     AUDIT_INTEGRITY_RULE);
	if (!ab)
		return;

	audit_log_format(ab, "file=");
	audit_log_untrustedstring(ab, filename);
	audit_log_format(ab, " hash=");
	audit_log_untrustedstring(ab, hash);

	audit_log_task_info(ab, current);
	audit_log_end(ab);

	iint->flags |= IMA_AUDITED;
}

const char *ima_d_path(struct path *path, char **pathbuf)
{
	char *pathname = NULL;

	/* We will allow 11 spaces for ' (deleted)' to be appended */
	*pathbuf = kmalloc(PATH_MAX + 11, GFP_KERNEL);
	if (*pathbuf) {
		pathname = d_path(path, *pathbuf, PATH_MAX + 11);
		if (IS_ERR(pathname)) {
			kfree(*pathbuf);
			*pathbuf = NULL;
			pathname = NULL;
		}
	}
	return pathname;
}
Commit	Line	Data
3323eec9 MZ	1	/*
	2	* Copyright (C) 2008 IBM Corporation
	3	*
	4	* Author: Mimi Zohar <zohar@us.ibm.com>
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License as
	8	* published by the Free Software Foundation, version 2 of the
	9	* License.
	10	*
	11	* File: ima_api.c
2fe5d6de MZ	12	* Implements must_appraise_or_measure, collect_measurement,
2fe5d6de MZ	13	* appraise_measurement, store_measurement and store_template.
3323eec9 MZ	14	*/
3323eec9 MZ	15	#include <linux/module.h>
5a0e3ad6	16	#include <linux/slab.h>
2fe5d6de MZ	17	#include <linux/file.h>
	18	#include <linux/fs.h>
	19	#include <linux/xattr.h>
	20	#include <linux/evm.h>
ea593993	21	#include <crypto/hash_info.h>
3323eec9	22	#include "ima.h"
2fe5d6de	23
7bc5f447 RS	24	/*
	25	* ima_alloc_init_template - create and initialize a new template entry
	26	*/
	27	int ima_alloc_init_template(struct integrity_iint_cache *iint,
	28	struct file file, const unsigned char filename,
	29	struct ima_template_entry **entry)
	30	{
a71dc65d RS	31	struct ima_template_desc *template_desc = ima_template_desc_current();
a71dc65d RS	32	int i, result = 0;
7bc5f447	33
a71dc65d RS	34	entry = kzalloc(sizeof(entry) + template_desc->num_fields
	35	sizeof(struct ima_field_data), GFP_NOFS);
	36	if (!*entry)
7bc5f447 RS	37	return -ENOMEM;
7bc5f447 RS	38
a71dc65d RS	39	for (i = 0; i < template_desc->num_fields; i++) {
	40	struct ima_template_field *field = template_desc->fields[i];
	41	u32 len;
7bc5f447	42
a71dc65d RS	43	result = field->field_init(iint, file, filename,
	44	&((*entry)->template_data[i]));
	45	if (result != 0)
	46	goto out;
7bc5f447	47
a71dc65d RS	48	len = (*entry)->template_data[i].len;
	49	(*entry)->template_data_len += sizeof(len);
	50	(*entry)->template_data_len += len;
	51	}
	52	(*entry)->template_desc = template_desc;
7bc5f447	53	return 0;
a71dc65d RS	54	out:
	55	kfree(*entry);
	56	*entry = NULL;
7bc5f447 RS	57	return result;
	58	}
	59
3323eec9 MZ	60	/*
	61	* ima_store_template - store ima template measurements
	62	*
	63	* Calculate the hash of a template entry, add the template entry
	64	* to an ordered list of measurement entries maintained inside the kernel,
	65	* and also update the aggregate integrity value (maintained inside the
	66	* configured TPM PCR) over the hashes of the current list of measurement
	67	* entries.
	68	*
	69	* Applications retrieve the current kernel-held measurement list through
	70	* the securityfs entries in /sys/kernel/security/ima. The signed aggregate
	71	* TPM PCR (called quote) can be retrieved using a TPM user space library
	72	* and is used to validate the measurement list.
	73	*
	74	* Returns 0 on success, error code otherwise
	75	*/
	76	int ima_store_template(struct ima_template_entry *entry,
9803d413 RS	77	int violation, struct inode *inode,
9803d413 RS	78	const unsigned char *filename)
3323eec9 MZ	79	{
	80	const char *op = "add_template_measure";
	81	const char *audit_cause = "hashing_error";
a71dc65d	82	char *template_name = entry->template_desc->name;
3323eec9	83	int result;
a35c3fb6 DK	84	struct {
a35c3fb6 DK	85	struct ima_digest_data hdr;
140d8022	86	char digest[TPM_DIGEST_SIZE];
a35c3fb6	87	} hash;
3323eec9	88
3323eec9	89	if (!violation) {
a71dc65d RS	90	int num_fields = entry->template_desc->num_fields;
a71dc65d RS	91
ea593993 DK	92	/* this function uses default algo */
ea593993 DK	93	hash.hdr.algo = HASH_ALGO_SHA1;
a71dc65d RS	94	result = ima_calc_field_array_hash(&entry->template_data[0],
a71dc65d RS	95	num_fields, &hash.hdr);
3323eec9 MZ	96	if (result < 0) {
3323eec9 MZ	97	integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
a71dc65d	98	template_name, op,
3323eec9 MZ	99	audit_cause, result, 0);
	100	return result;
	101	}
a35c3fb6	102	memcpy(entry->digest, hash.hdr.digest, hash.hdr.length);
3323eec9	103	}
9803d413	104	result = ima_add_template_entry(entry, violation, op, inode, filename);
3323eec9 MZ	105	return result;
	106	}
	107
	108	/*
	109	* ima_add_violation - add violation to measurement list.
	110	*
	111	* Violations are flagged in the measurement list with zero hash values.
	112	* By extending the PCR with 0xFF's instead of with zeroes, the PCR
	113	* value is invalidated.
	114	*/
7d802a22	115	void ima_add_violation(struct file file, const unsigned char filename,
3323eec9 MZ	116	const char op, const char cause)
	117	{
	118	struct ima_template_entry *entry;
7d802a22	119	struct inode *inode = file->f_dentry->d_inode;
3323eec9 MZ	120	int violation = 1;
	121	int result;
	122
	123	/* can overflow, only indicator */
	124	atomic_long_inc(&ima_htable.violations);
	125
7bc5f447 RS	126	result = ima_alloc_init_template(NULL, file, filename, &entry);
7bc5f447 RS	127	if (result < 0) {
3323eec9 MZ	128	result = -ENOMEM;
	129	goto err_out;
	130	}
9803d413	131	result = ima_store_template(entry, violation, inode, filename);
3323eec9 MZ	132	if (result < 0)
	133	kfree(entry);
	134	err_out:
	135	integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
	136	op, cause, result, 0);
	137	}
	138
	139	/**
d9d300cd	140	* ima_get_action - appraise & measure decision based on policy.
3323eec9 MZ	141	* @inode: pointer to inode to measure
3323eec9 MZ	142	* @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXECUTE)
16cac49f	143	* @function: calling function (FILE_CHECK, BPRM_CHECK, MMAP_CHECK, MODULE_CHECK)
3323eec9 MZ	144	*
	145	* The policy is defined in terms of keypairs:
	146	* subj=, obj=, type=, func=, mask=, fsmagic=
	147	* subj,obj, and type: are LSM specific.
16cac49f	148	* func: FILE_CHECK \| BPRM_CHECK \| MMAP_CHECK \| MODULE_CHECK
3323eec9 MZ	149	* mask: contains the permission mask
	150	* fsmagic: hex value
	151	*
2fe5d6de MZ	152	* Returns IMA_MEASURE, IMA_APPRAISE mask.
	153	*
	154	*/
d9d300cd	155	int ima_get_action(struct inode *inode, int mask, int function)
3323eec9	156	{
e7c568e0	157	int flags = IMA_MEASURE \| IMA_AUDIT \| IMA_APPRAISE;
2fe5d6de MZ	158
	159	if (!ima_appraise)
	160	flags &= ~IMA_APPRAISE;
	161
	162	return ima_match_policy(inode, function, mask, flags);
	163	}
3323eec9	164
2fe5d6de MZ	165	int ima_must_measure(struct inode *inode, int mask, int function)
	166	{
	167	return ima_match_policy(inode, function, mask, IMA_MEASURE);
3323eec9 MZ	168	}
	169
	170	/*
	171	* ima_collect_measurement - collect file measurement
	172	*
	173	* Calculate the file hash, if it doesn't already exist,
	174	* storing the measurement and i_version in the iint.
	175	*
	176	* Must be called with iint->mutex held.
	177	*
	178	* Return 0 on success, error code otherwise
	179	*/
f381c272	180	int ima_collect_measurement(struct integrity_iint_cache *iint,
d3634d0f DK	181	struct file *file,
	182	struct evm_ima_xattr_data **xattr_value,
	183	int *xattr_len)
3323eec9	184	{
496ad9aa	185	struct inode *inode = file_inode(file);
2fe5d6de MZ	186	const char *filename = file->f_dentry->d_name.name;
2fe5d6de MZ	187	int result = 0;
a35c3fb6 DK	188	struct {
	189	struct ima_digest_data hdr;
	190	char digest[IMA_MAX_DIGEST_SIZE];
	191	} hash;
3323eec9	192
d3634d0f DK	193	if (xattr_value)
	194	*xattr_len = ima_read_xattr(file->f_dentry, xattr_value);
	195
2fe5d6de	196	if (!(iint->flags & IMA_COLLECTED)) {
496ad9aa	197	u64 i_version = file_inode(file)->i_version;
3323eec9	198
c7c8bb23	199	/* use default hash algorithm */
a35c3fb6	200	hash.hdr.algo = ima_hash_algo;
d3634d0f DK	201
d3634d0f DK	202	if (xattr_value)
a35c3fb6	203	ima_get_hash_algo(xattr_value, xattr_len, &hash.hdr);
d3634d0f	204
a35c3fb6	205	result = ima_calc_file_hash(file, &hash.hdr);
2fe5d6de	206	if (!result) {
a35c3fb6 DK	207	int length = sizeof(hash.hdr) + hash.hdr.length;
	208	void *tmpbuf = krealloc(iint->ima_hash, length,
	209	GFP_NOFS);
	210	if (tmpbuf) {
	211	iint->ima_hash = tmpbuf;
	212	memcpy(iint->ima_hash, &hash, length);
	213	iint->version = i_version;
	214	iint->flags \|= IMA_COLLECTED;
	215	} else
	216	result = -ENOMEM;
2fe5d6de	217	}
3323eec9	218	}
2fe5d6de MZ	219	if (result)
	220	integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
	221	filename, "collect_data", "failed",
	222	result, 0);
3323eec9 MZ	223	return result;
	224	}
	225
	226	/*
	227	* ima_store_measurement - store file measurement
	228	*
	229	* Create an "ima" template and then store the template by calling
	230	* ima_store_template.
	231	*
	232	* We only get here if the inode has not already been measured,
	233	* but the measurement could already exist:
	234	* - multiple copies of the same file on either the same or
	235	* different filesystems.
	236	* - the inode was previously flushed as well as the iint info,
	237	* containing the hashing info.
	238	*
	239	* Must be called with iint->mutex held.
	240	*/
f381c272 MZ	241	void ima_store_measurement(struct integrity_iint_cache *iint,
f381c272 MZ	242	struct file file, const unsigned char filename)
3323eec9 MZ	243	{
	244	const char *op = "add_template_measure";
	245	const char *audit_cause = "ENOMEM";
	246	int result = -ENOMEM;
496ad9aa	247	struct inode *inode = file_inode(file);
3323eec9 MZ	248	struct ima_template_entry *entry;
	249	int violation = 0;
	250
2fe5d6de MZ	251	if (iint->flags & IMA_MEASURED)
	252	return;
	253
7bc5f447 RS	254	result = ima_alloc_init_template(iint, file, filename, &entry);
7bc5f447 RS	255	if (result < 0) {
3323eec9 MZ	256	integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
	257	op, audit_cause, result, 0);
	258	return;
	259	}
3323eec9	260
9803d413	261	result = ima_store_template(entry, violation, inode, filename);
45fae749	262	if (!result \|\| result == -EEXIST)
3323eec9	263	iint->flags \|= IMA_MEASURED;
45fae749	264	if (result < 0)
3323eec9 MZ	265	kfree(entry);
3323eec9 MZ	266	}
e7c568e0 PM	267
	268	void ima_audit_measurement(struct integrity_iint_cache *iint,
	269	const unsigned char *filename)
	270	{
	271	struct audit_buffer *ab;
a35c3fb6	272	char hash[(iint->ima_hash->length * 2) + 1];
e7c568e0 PM	273	int i;
	274
	275	if (iint->flags & IMA_AUDITED)
	276	return;
	277
a35c3fb6 DK	278	for (i = 0; i < iint->ima_hash->length; i++)
a35c3fb6 DK	279	hex_byte_pack(hash + (i * 2), iint->ima_hash->digest[i]);
e7c568e0 PM	280	hash[i * 2] = '\0';
	281
	282	ab = audit_log_start(current->audit_context, GFP_KERNEL,
	283	AUDIT_INTEGRITY_RULE);
	284	if (!ab)
	285	return;
	286
	287	audit_log_format(ab, "file=");
	288	audit_log_untrustedstring(ab, filename);
	289	audit_log_format(ab, " hash=");
	290	audit_log_untrustedstring(ab, hash);
	291
	292	audit_log_task_info(ab, current);
	293	audit_log_end(ab);
	294
	295	iint->flags \|= IMA_AUDITED;
	296	}
ea1046d4 DK	297
	298	const char ima_d_path(struct path path, char **pathbuf)
	299	{
	300	char *pathname = NULL;
	301
	302	/* We will allow 11 spaces for ' (deleted)' to be appended */
	303	*pathbuf = kmalloc(PATH_MAX + 11, GFP_KERNEL);
	304	if (*pathbuf) {
	305	pathname = d_path(path, *pathbuf, PATH_MAX + 11);
	306	if (IS_ERR(pathname)) {
	307	kfree(*pathbuf);
	308	*pathbuf = NULL;
	309	pathname = NULL;
	310	}
	311	}
	312	return pathname;
	313	}