[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 "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[IMA_MAX_DIGEST_SIZE];
	} hash;

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

	if (!violation) {
		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>
3323eec9	21	#include "ima.h"
2fe5d6de	22
523979ad	23	static const char *IMA_TEMPLATE_NAME = "ima";
3323eec9 MZ	24
	25	/*
	26	* ima_store_template - store ima template measurements
	27	*
	28	* Calculate the hash of a template entry, add the template entry
	29	* to an ordered list of measurement entries maintained inside the kernel,
	30	* and also update the aggregate integrity value (maintained inside the
	31	* configured TPM PCR) over the hashes of the current list of measurement
	32	* entries.
	33	*
	34	* Applications retrieve the current kernel-held measurement list through
	35	* the securityfs entries in /sys/kernel/security/ima. The signed aggregate
	36	* TPM PCR (called quote) can be retrieved using a TPM user space library
	37	* and is used to validate the measurement list.
	38	*
	39	* Returns 0 on success, error code otherwise
	40	*/
	41	int ima_store_template(struct ima_template_entry *entry,
	42	int violation, struct inode *inode)
	43	{
	44	const char *op = "add_template_measure";
	45	const char *audit_cause = "hashing_error";
	46	int result;
a35c3fb6 DK	47	struct {
	48	struct ima_digest_data hdr;
	49	char digest[IMA_MAX_DIGEST_SIZE];
	50	} hash;
3323eec9 MZ	51
	52	memset(entry->digest, 0, sizeof(entry->digest));
	53	entry->template_name = IMA_TEMPLATE_NAME;
	54	entry->template_len = sizeof(entry->template);
	55
	56	if (!violation) {
50af5544	57	result = ima_calc_buffer_hash(&entry->template,
a35c3fb6	58	entry->template_len, &hash.hdr);
3323eec9 MZ	59	if (result < 0) {
	60	integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
	61	entry->template_name, op,
	62	audit_cause, result, 0);
	63	return result;
	64	}
a35c3fb6	65	memcpy(entry->digest, hash.hdr.digest, hash.hdr.length);
3323eec9 MZ	66	}
	67	result = ima_add_template_entry(entry, violation, op, inode);
	68	return result;
	69	}
	70
	71	/*
	72	* ima_add_violation - add violation to measurement list.
	73	*
	74	* Violations are flagged in the measurement list with zero hash values.
	75	* By extending the PCR with 0xFF's instead of with zeroes, the PCR
	76	* value is invalidated.
	77	*/
	78	void ima_add_violation(struct inode inode, const unsigned char filename,
	79	const char op, const char cause)
	80	{
	81	struct ima_template_entry *entry;
	82	int violation = 1;
	83	int result;
	84
	85	/* can overflow, only indicator */
	86	atomic_long_inc(&ima_htable.violations);
	87
	88	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
	89	if (!entry) {
	90	result = -ENOMEM;
	91	goto err_out;
	92	}
	93	memset(&entry->template, 0, sizeof(entry->template));
	94	strncpy(entry->template.file_name, filename, IMA_EVENT_NAME_LEN_MAX);
	95	result = ima_store_template(entry, violation, inode);
	96	if (result < 0)
	97	kfree(entry);
	98	err_out:
	99	integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
	100	op, cause, result, 0);
	101	}
	102
	103	/**
d9d300cd	104	* ima_get_action - appraise & measure decision based on policy.
3323eec9 MZ	105	* @inode: pointer to inode to measure
3323eec9 MZ	106	* @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXECUTE)
16cac49f	107	* @function: calling function (FILE_CHECK, BPRM_CHECK, MMAP_CHECK, MODULE_CHECK)
3323eec9 MZ	108	*
	109	* The policy is defined in terms of keypairs:
	110	* subj=, obj=, type=, func=, mask=, fsmagic=
	111	* subj,obj, and type: are LSM specific.
16cac49f	112	* func: FILE_CHECK \| BPRM_CHECK \| MMAP_CHECK \| MODULE_CHECK
3323eec9 MZ	113	* mask: contains the permission mask
	114	* fsmagic: hex value
	115	*
2fe5d6de MZ	116	* Returns IMA_MEASURE, IMA_APPRAISE mask.
	117	*
	118	*/
d9d300cd	119	int ima_get_action(struct inode *inode, int mask, int function)
3323eec9	120	{
e7c568e0	121	int flags = IMA_MEASURE \| IMA_AUDIT \| IMA_APPRAISE;
2fe5d6de MZ	122
	123	if (!ima_appraise)
	124	flags &= ~IMA_APPRAISE;
	125
	126	return ima_match_policy(inode, function, mask, flags);
	127	}
3323eec9	128
2fe5d6de MZ	129	int ima_must_measure(struct inode *inode, int mask, int function)
	130	{
	131	return ima_match_policy(inode, function, mask, IMA_MEASURE);
3323eec9 MZ	132	}
	133
	134	/*
	135	* ima_collect_measurement - collect file measurement
	136	*
	137	* Calculate the file hash, if it doesn't already exist,
	138	* storing the measurement and i_version in the iint.
	139	*
	140	* Must be called with iint->mutex held.
	141	*
	142	* Return 0 on success, error code otherwise
	143	*/
f381c272	144	int ima_collect_measurement(struct integrity_iint_cache *iint,
d3634d0f DK	145	struct file *file,
	146	struct evm_ima_xattr_data **xattr_value,
	147	int *xattr_len)
3323eec9	148	{
496ad9aa	149	struct inode *inode = file_inode(file);
2fe5d6de MZ	150	const char *filename = file->f_dentry->d_name.name;
2fe5d6de MZ	151	int result = 0;
a35c3fb6 DK	152	struct {
	153	struct ima_digest_data hdr;
	154	char digest[IMA_MAX_DIGEST_SIZE];
	155	} hash;
3323eec9	156
d3634d0f DK	157	if (xattr_value)
	158	*xattr_len = ima_read_xattr(file->f_dentry, xattr_value);
	159
2fe5d6de	160	if (!(iint->flags & IMA_COLLECTED)) {
496ad9aa	161	u64 i_version = file_inode(file)->i_version;
3323eec9	162
c7c8bb23	163	/* use default hash algorithm */
a35c3fb6	164	hash.hdr.algo = ima_hash_algo;
d3634d0f DK	165
d3634d0f DK	166	if (xattr_value)
a35c3fb6	167	ima_get_hash_algo(xattr_value, xattr_len, &hash.hdr);
d3634d0f	168
a35c3fb6	169	result = ima_calc_file_hash(file, &hash.hdr);
2fe5d6de	170	if (!result) {
a35c3fb6 DK	171	int length = sizeof(hash.hdr) + hash.hdr.length;
	172	void *tmpbuf = krealloc(iint->ima_hash, length,
	173	GFP_NOFS);
	174	if (tmpbuf) {
	175	iint->ima_hash = tmpbuf;
	176	memcpy(iint->ima_hash, &hash, length);
	177	iint->version = i_version;
	178	iint->flags \|= IMA_COLLECTED;
	179	} else
	180	result = -ENOMEM;
2fe5d6de	181	}
3323eec9	182	}
2fe5d6de MZ	183	if (result)
	184	integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
	185	filename, "collect_data", "failed",
	186	result, 0);
3323eec9 MZ	187	return result;
	188	}
	189
	190	/*
	191	* ima_store_measurement - store file measurement
	192	*
	193	* Create an "ima" template and then store the template by calling
	194	* ima_store_template.
	195	*
	196	* We only get here if the inode has not already been measured,
	197	* but the measurement could already exist:
	198	* - multiple copies of the same file on either the same or
	199	* different filesystems.
	200	* - the inode was previously flushed as well as the iint info,
	201	* containing the hashing info.
	202	*
	203	* Must be called with iint->mutex held.
	204	*/
f381c272 MZ	205	void ima_store_measurement(struct integrity_iint_cache *iint,
f381c272 MZ	206	struct file file, const unsigned char filename)
3323eec9 MZ	207	{
	208	const char *op = "add_template_measure";
	209	const char *audit_cause = "ENOMEM";
	210	int result = -ENOMEM;
496ad9aa	211	struct inode *inode = file_inode(file);
3323eec9 MZ	212	struct ima_template_entry *entry;
	213	int violation = 0;
	214
2fe5d6de MZ	215	if (iint->flags & IMA_MEASURED)
	216	return;
	217
3323eec9 MZ	218	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
	219	if (!entry) {
	220	integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
	221	op, audit_cause, result, 0);
	222	return;
	223	}
	224	memset(&entry->template, 0, sizeof(entry->template));
a35c3fb6 DK	225	if (iint->ima_hash->algo != ima_hash_algo) {
	226	struct {
	227	struct ima_digest_data hdr;
	228	char digest[IMA_MAX_DIGEST_SIZE];
	229	} hash;
c7c8bb23	230
a35c3fb6 DK	231	hash.hdr.algo = ima_hash_algo;
a35c3fb6 DK	232	result = ima_calc_file_hash(file, &hash.hdr);
c7c8bb23 DK	233	if (result)
	234	integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
	235	filename, "collect_data", "failed",
	236	result, 0);
	237	else
a35c3fb6 DK	238	memcpy(entry->template.digest, hash.hdr.digest,
a35c3fb6 DK	239	hash.hdr.length);
c7c8bb23	240	} else
a35c3fb6 DK	241	memcpy(entry->template.digest, iint->ima_hash->digest,
a35c3fb6 DK	242	iint->ima_hash->length);
08e1b76a MZ	243	strcpy(entry->template.file_name,
	244	(strlen(filename) > IMA_EVENT_NAME_LEN_MAX) ?
	245	file->f_dentry->d_name.name : filename);
3323eec9 MZ	246
3323eec9 MZ	247	result = ima_store_template(entry, violation, inode);
45fae749	248	if (!result \|\| result == -EEXIST)
3323eec9	249	iint->flags \|= IMA_MEASURED;
45fae749	250	if (result < 0)
3323eec9 MZ	251	kfree(entry);
3323eec9 MZ	252	}
e7c568e0 PM	253
	254	void ima_audit_measurement(struct integrity_iint_cache *iint,
	255	const unsigned char *filename)
	256	{
	257	struct audit_buffer *ab;
a35c3fb6	258	char hash[(iint->ima_hash->length * 2) + 1];
e7c568e0 PM	259	int i;
	260
	261	if (iint->flags & IMA_AUDITED)
	262	return;
	263
a35c3fb6 DK	264	for (i = 0; i < iint->ima_hash->length; i++)
a35c3fb6 DK	265	hex_byte_pack(hash + (i * 2), iint->ima_hash->digest[i]);
e7c568e0 PM	266	hash[i * 2] = '\0';
	267
	268	ab = audit_log_start(current->audit_context, GFP_KERNEL,
	269	AUDIT_INTEGRITY_RULE);
	270	if (!ab)
	271	return;
	272
	273	audit_log_format(ab, "file=");
	274	audit_log_untrustedstring(ab, filename);
	275	audit_log_format(ab, " hash=");
	276	audit_log_untrustedstring(ab, hash);
	277
	278	audit_log_task_info(ab, current);
	279	audit_log_end(ab);
	280
	281	iint->flags \|= IMA_AUDITED;
	282	}
ea1046d4 DK	283
	284	const char ima_d_path(struct path path, char **pathbuf)
	285	{
	286	char *pathname = NULL;
	287
	288	/* We will allow 11 spaces for ' (deleted)' to be appended */
	289	*pathbuf = kmalloc(PATH_MAX + 11, GFP_KERNEL);
	290	if (*pathbuf) {
	291	pathname = d_path(path, *pathbuf, PATH_MAX + 11);
	292	if (IS_ERR(pathname)) {
	293	kfree(*pathbuf);
	294	*pathbuf = NULL;
	295	pathname = NULL;
	296	}
	297	}
	298	return pathname;
	299	}