[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 unsigned char *filename)
{
	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, 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);

	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, 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;

	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, 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
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,
9803d413 RS	43	int violation, struct inode *inode,
9803d413 RS	44	const unsigned char *filename)
3323eec9 MZ	45	{
	46	const char *op = "add_template_measure";
	47	const char *audit_cause = "hashing_error";
	48	int result;
a35c3fb6 DK	49	struct {
a35c3fb6 DK	50	struct ima_digest_data hdr;
140d8022	51	char digest[TPM_DIGEST_SIZE];
a35c3fb6	52	} hash;
3323eec9 MZ	53
	54	memset(entry->digest, 0, sizeof(entry->digest));
	55	entry->template_name = IMA_TEMPLATE_NAME;
	56	entry->template_len = sizeof(entry->template);
	57
	58	if (!violation) {
ea593993 DK	59	/* this function uses default algo */
ea593993 DK	60	hash.hdr.algo = HASH_ALGO_SHA1;
50af5544	61	result = ima_calc_buffer_hash(&entry->template,
a35c3fb6	62	entry->template_len, &hash.hdr);
3323eec9 MZ	63	if (result < 0) {
	64	integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
	65	entry->template_name, op,
	66	audit_cause, result, 0);
	67	return result;
	68	}
a35c3fb6	69	memcpy(entry->digest, hash.hdr.digest, hash.hdr.length);
3323eec9	70	}
9803d413	71	result = ima_add_template_entry(entry, violation, op, inode, filename);
3323eec9 MZ	72	return result;
	73	}
	74
	75	/*
	76	* ima_add_violation - add violation to measurement list.
	77	*
	78	* Violations are flagged in the measurement list with zero hash values.
	79	* By extending the PCR with 0xFF's instead of with zeroes, the PCR
	80	* value is invalidated.
	81	*/
7d802a22	82	void ima_add_violation(struct file file, const unsigned char filename,
3323eec9 MZ	83	const char op, const char cause)
	84	{
	85	struct ima_template_entry *entry;
7d802a22	86	struct inode *inode = file->f_dentry->d_inode;
3323eec9 MZ	87	int violation = 1;
	88	int result;
	89
	90	/* can overflow, only indicator */
	91	atomic_long_inc(&ima_htable.violations);
	92
	93	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
	94	if (!entry) {
	95	result = -ENOMEM;
	96	goto err_out;
	97	}
	98	memset(&entry->template, 0, sizeof(entry->template));
	99	strncpy(entry->template.file_name, filename, IMA_EVENT_NAME_LEN_MAX);
9803d413	100	result = ima_store_template(entry, violation, inode, filename);
3323eec9 MZ	101	if (result < 0)
	102	kfree(entry);
	103	err_out:
	104	integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
	105	op, cause, result, 0);
	106	}
	107
	108	/**
d9d300cd	109	* ima_get_action - appraise & measure decision based on policy.
3323eec9 MZ	110	* @inode: pointer to inode to measure
3323eec9 MZ	111	* @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXECUTE)
16cac49f	112	* @function: calling function (FILE_CHECK, BPRM_CHECK, MMAP_CHECK, MODULE_CHECK)
3323eec9 MZ	113	*
	114	* The policy is defined in terms of keypairs:
	115	* subj=, obj=, type=, func=, mask=, fsmagic=
	116	* subj,obj, and type: are LSM specific.
16cac49f	117	* func: FILE_CHECK \| BPRM_CHECK \| MMAP_CHECK \| MODULE_CHECK
3323eec9 MZ	118	* mask: contains the permission mask
	119	* fsmagic: hex value
	120	*
2fe5d6de MZ	121	* Returns IMA_MEASURE, IMA_APPRAISE mask.
	122	*
	123	*/
d9d300cd	124	int ima_get_action(struct inode *inode, int mask, int function)
3323eec9	125	{
e7c568e0	126	int flags = IMA_MEASURE \| IMA_AUDIT \| IMA_APPRAISE;
2fe5d6de MZ	127
	128	if (!ima_appraise)
	129	flags &= ~IMA_APPRAISE;
	130
	131	return ima_match_policy(inode, function, mask, flags);
	132	}
3323eec9	133
2fe5d6de MZ	134	int ima_must_measure(struct inode *inode, int mask, int function)
	135	{
	136	return ima_match_policy(inode, function, mask, IMA_MEASURE);
3323eec9 MZ	137	}
	138
	139	/*
	140	* ima_collect_measurement - collect file measurement
	141	*
	142	* Calculate the file hash, if it doesn't already exist,
	143	* storing the measurement and i_version in the iint.
	144	*
	145	* Must be called with iint->mutex held.
	146	*
	147	* Return 0 on success, error code otherwise
	148	*/
f381c272	149	int ima_collect_measurement(struct integrity_iint_cache *iint,
d3634d0f DK	150	struct file *file,
	151	struct evm_ima_xattr_data **xattr_value,
	152	int *xattr_len)
3323eec9	153	{
496ad9aa	154	struct inode *inode = file_inode(file);
2fe5d6de MZ	155	const char *filename = file->f_dentry->d_name.name;
2fe5d6de MZ	156	int result = 0;
a35c3fb6 DK	157	struct {
	158	struct ima_digest_data hdr;
	159	char digest[IMA_MAX_DIGEST_SIZE];
	160	} hash;
3323eec9	161
d3634d0f DK	162	if (xattr_value)
	163	*xattr_len = ima_read_xattr(file->f_dentry, xattr_value);
	164
2fe5d6de	165	if (!(iint->flags & IMA_COLLECTED)) {
496ad9aa	166	u64 i_version = file_inode(file)->i_version;
3323eec9	167
c7c8bb23	168	/* use default hash algorithm */
a35c3fb6	169	hash.hdr.algo = ima_hash_algo;
d3634d0f DK	170
d3634d0f DK	171	if (xattr_value)
a35c3fb6	172	ima_get_hash_algo(xattr_value, xattr_len, &hash.hdr);
d3634d0f	173
a35c3fb6	174	result = ima_calc_file_hash(file, &hash.hdr);
2fe5d6de	175	if (!result) {
a35c3fb6 DK	176	int length = sizeof(hash.hdr) + hash.hdr.length;
	177	void *tmpbuf = krealloc(iint->ima_hash, length,
	178	GFP_NOFS);
	179	if (tmpbuf) {
	180	iint->ima_hash = tmpbuf;
	181	memcpy(iint->ima_hash, &hash, length);
	182	iint->version = i_version;
	183	iint->flags \|= IMA_COLLECTED;
	184	} else
	185	result = -ENOMEM;
2fe5d6de	186	}
3323eec9	187	}
2fe5d6de MZ	188	if (result)
	189	integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
	190	filename, "collect_data", "failed",
	191	result, 0);
3323eec9 MZ	192	return result;
	193	}
	194
	195	/*
	196	* ima_store_measurement - store file measurement
	197	*
	198	* Create an "ima" template and then store the template by calling
	199	* ima_store_template.
	200	*
	201	* We only get here if the inode has not already been measured,
	202	* but the measurement could already exist:
	203	* - multiple copies of the same file on either the same or
	204	* different filesystems.
	205	* - the inode was previously flushed as well as the iint info,
	206	* containing the hashing info.
	207	*
	208	* Must be called with iint->mutex held.
	209	*/
f381c272 MZ	210	void ima_store_measurement(struct integrity_iint_cache *iint,
f381c272 MZ	211	struct file file, const unsigned char filename)
3323eec9 MZ	212	{
	213	const char *op = "add_template_measure";
	214	const char *audit_cause = "ENOMEM";
	215	int result = -ENOMEM;
496ad9aa	216	struct inode *inode = file_inode(file);
3323eec9 MZ	217	struct ima_template_entry *entry;
	218	int violation = 0;
	219
2fe5d6de MZ	220	if (iint->flags & IMA_MEASURED)
	221	return;
	222
3323eec9 MZ	223	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
	224	if (!entry) {
	225	integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
	226	op, audit_cause, result, 0);
	227	return;
	228	}
	229	memset(&entry->template, 0, sizeof(entry->template));
a35c3fb6 DK	230	if (iint->ima_hash->algo != ima_hash_algo) {
	231	struct {
	232	struct ima_digest_data hdr;
	233	char digest[IMA_MAX_DIGEST_SIZE];
	234	} hash;
c7c8bb23	235
a35c3fb6 DK	236	hash.hdr.algo = ima_hash_algo;
a35c3fb6 DK	237	result = ima_calc_file_hash(file, &hash.hdr);
c7c8bb23 DK	238	if (result)
	239	integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
	240	filename, "collect_data", "failed",
	241	result, 0);
	242	else
a35c3fb6 DK	243	memcpy(entry->template.digest, hash.hdr.digest,
a35c3fb6 DK	244	hash.hdr.length);
c7c8bb23	245	} else
a35c3fb6 DK	246	memcpy(entry->template.digest, iint->ima_hash->digest,
a35c3fb6 DK	247	iint->ima_hash->length);
08e1b76a MZ	248	strcpy(entry->template.file_name,
	249	(strlen(filename) > IMA_EVENT_NAME_LEN_MAX) ?
	250	file->f_dentry->d_name.name : filename);
3323eec9	251
9803d413	252	result = ima_store_template(entry, violation, inode, filename);
45fae749	253	if (!result \|\| result == -EEXIST)
3323eec9	254	iint->flags \|= IMA_MEASURED;
45fae749	255	if (result < 0)
3323eec9 MZ	256	kfree(entry);
3323eec9 MZ	257	}
e7c568e0 PM	258
	259	void ima_audit_measurement(struct integrity_iint_cache *iint,
	260	const unsigned char *filename)
	261	{
	262	struct audit_buffer *ab;
a35c3fb6	263	char hash[(iint->ima_hash->length * 2) + 1];
e7c568e0 PM	264	int i;
	265
	266	if (iint->flags & IMA_AUDITED)
	267	return;
	268
a35c3fb6 DK	269	for (i = 0; i < iint->ima_hash->length; i++)
a35c3fb6 DK	270	hex_byte_pack(hash + (i * 2), iint->ima_hash->digest[i]);
e7c568e0 PM	271	hash[i * 2] = '\0';
	272
	273	ab = audit_log_start(current->audit_context, GFP_KERNEL,
	274	AUDIT_INTEGRITY_RULE);
	275	if (!ab)
	276	return;
	277
	278	audit_log_format(ab, "file=");
	279	audit_log_untrustedstring(ab, filename);
	280	audit_log_format(ab, " hash=");
	281	audit_log_untrustedstring(ab, hash);
	282
	283	audit_log_task_info(ab, current);
	284	audit_log_end(ab);
	285
	286	iint->flags \|= IMA_AUDITED;
	287	}
ea1046d4 DK	288
	289	const char ima_d_path(struct path path, char **pathbuf)
	290	{
	291	char *pathname = NULL;
	292
	293	/* We will allow 11 spaces for ' (deleted)' to be appended */
	294	*pathbuf = kmalloc(PATH_MAX + 11, GFP_KERNEL);
	295	if (*pathbuf) {
	296	pathname = d_path(path, *pathbuf, PATH_MAX + 11);
	297	if (IS_ERR(pathname)) {
	298	kfree(*pathbuf);
	299	*pathbuf = NULL;
	300	pathname = NULL;
	301	}
	302	}
	303	return pathname;
	304	}