[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"

static const char *IMA_TEMPLATE_NAME = "ima";

/*
 * 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 char *op = "add_template_measure";
	const char *audit_cause = "hashing_error";
	int result;
	struct {
		struct ima_digest_data hdr;
		char digest[TPM_DIGEST_SIZE];
	} hash;

	memset(entry->digest, 0, sizeof(entry->digest));
	entry->template_name = IMA_TEMPLATE_NAME;
	entry->template_len = sizeof(entry->template);

	if (!violation) {
		/* this function uses default algo */
		hash.hdr.algo = HASH_ALGO_SHA1;
		result = ima_calc_buffer_hash(&entry->template,
					      entry->template_len, &hash.hdr);
		if (result < 0) {
			integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
					    entry->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);
	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 inode *inode, const unsigned char *filename,
		       const char *op, const char *cause)
{
	struct ima_template_entry *entry;
	int violation = 1;
	int result;

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

	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
	if (!entry) {
		result = -ENOMEM;
		goto err_out;
	}
	memset(&entry->template, 0, sizeof(entry->template));
	strncpy(entry->template.file_name, filename, IMA_EVENT_NAME_LEN_MAX);
	result = ima_store_template(entry, violation, inode);
	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;

	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
	if (!entry) {
		integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
				    op, audit_cause, result, 0);
		return;
	}
	memset(&entry->template, 0, sizeof(entry->template));
	if (iint->ima_hash->algo != ima_hash_algo) {
		struct {
			struct ima_digest_data hdr;
			char digest[IMA_MAX_DIGEST_SIZE];
		} hash;

		hash.hdr.algo = ima_hash_algo;
		result = ima_calc_file_hash(file, &hash.hdr);
		if (result)
			integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
					    filename, "collect_data", "failed",
					    result, 0);
		else
			memcpy(entry->template.digest, hash.hdr.digest,
			       hash.hdr.length);
	} else
		memcpy(entry->template.digest, iint->ima_hash->digest,
		       iint->ima_hash->length);
	strcpy(entry->template.file_name,
	       (strlen(filename) > IMA_EVENT_NAME_LEN_MAX) ?
	       file->f_dentry->d_name.name : filename);

	result = ima_store_template(entry, violation, inode);
	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
523979ad	24	static const char *IMA_TEMPLATE_NAME = "ima";
3323eec9 MZ	25
	26	/*
	27	* ima_store_template - store ima template measurements
	28	*
	29	* Calculate the hash of a template entry, add the template entry
	30	* to an ordered list of measurement entries maintained inside the kernel,
	31	* and also update the aggregate integrity value (maintained inside the
	32	* configured TPM PCR) over the hashes of the current list of measurement
	33	* entries.
	34	*
	35	* Applications retrieve the current kernel-held measurement list through
	36	* the securityfs entries in /sys/kernel/security/ima. The signed aggregate
	37	* TPM PCR (called quote) can be retrieved using a TPM user space library
	38	* and is used to validate the measurement list.
	39	*
	40	* Returns 0 on success, error code otherwise
	41	*/
	42	int ima_store_template(struct ima_template_entry *entry,
	43	int violation, struct inode *inode)
	44	{
	45	const char *op = "add_template_measure";
	46	const char *audit_cause = "hashing_error";
	47	int result;
a35c3fb6 DK	48	struct {
a35c3fb6 DK	49	struct ima_digest_data hdr;
140d8022	50	char digest[TPM_DIGEST_SIZE];
a35c3fb6	51	} hash;
3323eec9 MZ	52
	53	memset(entry->digest, 0, sizeof(entry->digest));
	54	entry->template_name = IMA_TEMPLATE_NAME;
	55	entry->template_len = sizeof(entry->template);
	56
	57	if (!violation) {
ea593993 DK	58	/* this function uses default algo */
ea593993 DK	59	hash.hdr.algo = HASH_ALGO_SHA1;
50af5544	60	result = ima_calc_buffer_hash(&entry->template,
a35c3fb6	61	entry->template_len, &hash.hdr);
3323eec9 MZ	62	if (result < 0) {
	63	integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
	64	entry->template_name, op,
	65	audit_cause, result, 0);
	66	return result;
	67	}
a35c3fb6	68	memcpy(entry->digest, hash.hdr.digest, hash.hdr.length);
3323eec9 MZ	69	}
	70	result = ima_add_template_entry(entry, violation, op, inode);
	71	return result;
	72	}
	73
	74	/*
	75	* ima_add_violation - add violation to measurement list.
	76	*
	77	* Violations are flagged in the measurement list with zero hash values.
	78	* By extending the PCR with 0xFF's instead of with zeroes, the PCR
	79	* value is invalidated.
	80	*/
	81	void ima_add_violation(struct inode inode, const unsigned char filename,
	82	const char op, const char cause)
	83	{
	84	struct ima_template_entry *entry;
	85	int violation = 1;
	86	int result;
	87
	88	/* can overflow, only indicator */
	89	atomic_long_inc(&ima_htable.violations);
	90
	91	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
	92	if (!entry) {
	93	result = -ENOMEM;
	94	goto err_out;
	95	}
	96	memset(&entry->template, 0, sizeof(entry->template));
	97	strncpy(entry->template.file_name, filename, IMA_EVENT_NAME_LEN_MAX);
	98	result = ima_store_template(entry, violation, inode);
	99	if (result < 0)
	100	kfree(entry);
	101	err_out:
	102	integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
	103	op, cause, result, 0);
	104	}
	105
	106	/**
d9d300cd	107	* ima_get_action - appraise & measure decision based on policy.
3323eec9 MZ	108	* @inode: pointer to inode to measure
3323eec9 MZ	109	* @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXECUTE)
16cac49f	110	* @function: calling function (FILE_CHECK, BPRM_CHECK, MMAP_CHECK, MODULE_CHECK)
3323eec9 MZ	111	*
	112	* The policy is defined in terms of keypairs:
	113	* subj=, obj=, type=, func=, mask=, fsmagic=
	114	* subj,obj, and type: are LSM specific.
16cac49f	115	* func: FILE_CHECK \| BPRM_CHECK \| MMAP_CHECK \| MODULE_CHECK
3323eec9 MZ	116	* mask: contains the permission mask
	117	* fsmagic: hex value
	118	*
2fe5d6de MZ	119	* Returns IMA_MEASURE, IMA_APPRAISE mask.
	120	*
	121	*/
d9d300cd	122	int ima_get_action(struct inode *inode, int mask, int function)
3323eec9	123	{
e7c568e0	124	int flags = IMA_MEASURE \| IMA_AUDIT \| IMA_APPRAISE;
2fe5d6de MZ	125
	126	if (!ima_appraise)
	127	flags &= ~IMA_APPRAISE;
	128
	129	return ima_match_policy(inode, function, mask, flags);
	130	}
3323eec9	131
2fe5d6de MZ	132	int ima_must_measure(struct inode *inode, int mask, int function)
	133	{
	134	return ima_match_policy(inode, function, mask, IMA_MEASURE);
3323eec9 MZ	135	}
	136
	137	/*
	138	* ima_collect_measurement - collect file measurement
	139	*
	140	* Calculate the file hash, if it doesn't already exist,
	141	* storing the measurement and i_version in the iint.
	142	*
	143	* Must be called with iint->mutex held.
	144	*
	145	* Return 0 on success, error code otherwise
	146	*/
f381c272	147	int ima_collect_measurement(struct integrity_iint_cache *iint,
d3634d0f DK	148	struct file *file,
	149	struct evm_ima_xattr_data **xattr_value,
	150	int *xattr_len)
3323eec9	151	{
496ad9aa	152	struct inode *inode = file_inode(file);
2fe5d6de MZ	153	const char *filename = file->f_dentry->d_name.name;
2fe5d6de MZ	154	int result = 0;
a35c3fb6 DK	155	struct {
	156	struct ima_digest_data hdr;
	157	char digest[IMA_MAX_DIGEST_SIZE];
	158	} hash;
3323eec9	159
d3634d0f DK	160	if (xattr_value)
	161	*xattr_len = ima_read_xattr(file->f_dentry, xattr_value);
	162
2fe5d6de	163	if (!(iint->flags & IMA_COLLECTED)) {
496ad9aa	164	u64 i_version = file_inode(file)->i_version;
3323eec9	165
c7c8bb23	166	/* use default hash algorithm */
a35c3fb6	167	hash.hdr.algo = ima_hash_algo;
d3634d0f DK	168
d3634d0f DK	169	if (xattr_value)
a35c3fb6	170	ima_get_hash_algo(xattr_value, xattr_len, &hash.hdr);
d3634d0f	171
a35c3fb6	172	result = ima_calc_file_hash(file, &hash.hdr);
2fe5d6de	173	if (!result) {
a35c3fb6 DK	174	int length = sizeof(hash.hdr) + hash.hdr.length;
	175	void *tmpbuf = krealloc(iint->ima_hash, length,
	176	GFP_NOFS);
	177	if (tmpbuf) {
	178	iint->ima_hash = tmpbuf;
	179	memcpy(iint->ima_hash, &hash, length);
	180	iint->version = i_version;
	181	iint->flags \|= IMA_COLLECTED;
	182	} else
	183	result = -ENOMEM;
2fe5d6de	184	}
3323eec9	185	}
2fe5d6de MZ	186	if (result)
	187	integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
	188	filename, "collect_data", "failed",
	189	result, 0);
3323eec9 MZ	190	return result;
	191	}
	192
	193	/*
	194	* ima_store_measurement - store file measurement
	195	*
	196	* Create an "ima" template and then store the template by calling
	197	* ima_store_template.
	198	*
	199	* We only get here if the inode has not already been measured,
	200	* but the measurement could already exist:
	201	* - multiple copies of the same file on either the same or
	202	* different filesystems.
	203	* - the inode was previously flushed as well as the iint info,
	204	* containing the hashing info.
	205	*
	206	* Must be called with iint->mutex held.
	207	*/
f381c272 MZ	208	void ima_store_measurement(struct integrity_iint_cache *iint,
f381c272 MZ	209	struct file file, const unsigned char filename)
3323eec9 MZ	210	{
	211	const char *op = "add_template_measure";
	212	const char *audit_cause = "ENOMEM";
	213	int result = -ENOMEM;
496ad9aa	214	struct inode *inode = file_inode(file);
3323eec9 MZ	215	struct ima_template_entry *entry;
	216	int violation = 0;
	217
2fe5d6de MZ	218	if (iint->flags & IMA_MEASURED)
	219	return;
	220
3323eec9 MZ	221	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
	222	if (!entry) {
	223	integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
	224	op, audit_cause, result, 0);
	225	return;
	226	}
	227	memset(&entry->template, 0, sizeof(entry->template));
a35c3fb6 DK	228	if (iint->ima_hash->algo != ima_hash_algo) {
	229	struct {
	230	struct ima_digest_data hdr;
	231	char digest[IMA_MAX_DIGEST_SIZE];
	232	} hash;
c7c8bb23	233
a35c3fb6 DK	234	hash.hdr.algo = ima_hash_algo;
a35c3fb6 DK	235	result = ima_calc_file_hash(file, &hash.hdr);
c7c8bb23 DK	236	if (result)
	237	integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
	238	filename, "collect_data", "failed",
	239	result, 0);
	240	else
a35c3fb6 DK	241	memcpy(entry->template.digest, hash.hdr.digest,
a35c3fb6 DK	242	hash.hdr.length);
c7c8bb23	243	} else
a35c3fb6 DK	244	memcpy(entry->template.digest, iint->ima_hash->digest,
a35c3fb6 DK	245	iint->ima_hash->length);
08e1b76a MZ	246	strcpy(entry->template.file_name,
	247	(strlen(filename) > IMA_EVENT_NAME_LEN_MAX) ?
	248	file->f_dentry->d_name.name : filename);
3323eec9 MZ	249
3323eec9 MZ	250	result = ima_store_template(entry, violation, inode);
45fae749	251	if (!result \|\| result == -EEXIST)
3323eec9	252	iint->flags \|= IMA_MEASURED;
45fae749	253	if (result < 0)
3323eec9 MZ	254	kfree(entry);
3323eec9 MZ	255	}
e7c568e0 PM	256
	257	void ima_audit_measurement(struct integrity_iint_cache *iint,
	258	const unsigned char *filename)
	259	{
	260	struct audit_buffer *ab;
a35c3fb6	261	char hash[(iint->ima_hash->length * 2) + 1];
e7c568e0 PM	262	int i;
	263
	264	if (iint->flags & IMA_AUDITED)
	265	return;
	266
a35c3fb6 DK	267	for (i = 0; i < iint->ima_hash->length; i++)
a35c3fb6 DK	268	hex_byte_pack(hash + (i * 2), iint->ima_hash->digest[i]);
e7c568e0 PM	269	hash[i * 2] = '\0';
	270
	271	ab = audit_log_start(current->audit_context, GFP_KERNEL,
	272	AUDIT_INTEGRITY_RULE);
	273	if (!ab)
	274	return;
	275
	276	audit_log_format(ab, "file=");
	277	audit_log_untrustedstring(ab, filename);
	278	audit_log_format(ab, " hash=");
	279	audit_log_untrustedstring(ab, hash);
	280
	281	audit_log_task_info(ab, current);
	282	audit_log_end(ab);
	283
	284	iint->flags \|= IMA_AUDITED;
	285	}
ea1046d4 DK	286
	287	const char ima_d_path(struct path path, char **pathbuf)
	288	{
	289	char *pathname = NULL;
	290
	291	/* We will allow 11 spaces for ' (deleted)' to be appended */
	292	*pathbuf = kmalloc(PATH_MAX + 11, GFP_KERNEL);
	293	if (*pathbuf) {
	294	pathname = d_path(path, *pathbuf, PATH_MAX + 11);
	295	if (IS_ERR(pathname)) {
	296	kfree(*pathbuf);
	297	*pathbuf = NULL;
	298	pathname = NULL;
	299	}
	300	}
	301	return pathname;
	302	}