security/integrity/ima/ima_template_lib.c - kernel/lockdown - Git at Google

 /*
  * Copyright (C) 2013 Politecnico di Torino, Italy
  *                    TORSEC group -- http://security.polito.it
  *
  * Author: Roberto Sassu <roberto.sassu@polito.it>
  *
  * 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_template_lib.c
  *      Library of supported template fields.
  */
 #include <crypto/hash_info.h>

 #include "ima_template_lib.h"

 static bool ima_template_hash_algo_allowed(u8 algo)
 {
 	if (algo == HASH_ALGO_SHA1 || algo == HASH_ALGO_MD5)
 		return true;

 	return false;
 }

 enum data_formats {
 	DATA_FMT_DIGEST = 0,
 	DATA_FMT_DIGEST_WITH_ALGO,
 	DATA_FMT_EVENT_NAME,
 	DATA_FMT_STRING,
 	DATA_FMT_HEX
 };

 static int ima_write_template_field_data(const void *data, const u32 datalen,
 					 enum data_formats datafmt,
 					 struct ima_field_data *field_data)
 {
 	u8 *buf, *buf_ptr;
 	u32 buflen;

 	switch (datafmt) {
 	case DATA_FMT_EVENT_NAME:
 		buflen = IMA_EVENT_NAME_LEN_MAX + 1;
 		break;
 	case DATA_FMT_STRING:
 		buflen = datalen + 1;
 		break;
 	default:
 		buflen = datalen;
 	}

 	buf = kzalloc(buflen, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;

 	memcpy(buf, data, datalen);

 	/*
 	 * Replace all space characters with underscore for event names and
 	 * strings. This avoid that, during the parsing of a measurements list,
 	 * filenames with spaces or that end with the suffix ' (deleted)' are
 	 * split into multiple template fields (the space is the delimitator
 	 * character for measurements lists in ASCII format).
 	 */
 	if (datafmt == DATA_FMT_EVENT_NAME || datafmt == DATA_FMT_STRING) {
 		for (buf_ptr = buf; buf_ptr - buf < datalen; buf_ptr++)
 			if (*buf_ptr == ' ')
 				*buf_ptr = '_';
 	}

 	field_data->data = buf;
 	field_data->len = buflen;
 	return 0;
 }

 static void ima_show_template_data_ascii(struct seq_file *m,
 					 enum ima_show_type show,
 					 enum data_formats datafmt,
 					 struct ima_field_data *field_data)
 {
 	u8 *buf_ptr = field_data->data, buflen = field_data->len;

 	switch (datafmt) {
 	case DATA_FMT_DIGEST_WITH_ALGO:
 		buf_ptr = strnchr(field_data->data, buflen, ':');
 		if (buf_ptr != field_data->data)
 			seq_printf(m, "%s", field_data->data);

 		/* skip ':' and '\0' */
 		buf_ptr += 2;
 		buflen -= buf_ptr - field_data->data;
 	case DATA_FMT_DIGEST:
 	case DATA_FMT_HEX:
 		if (!buflen)
 			break;
 		ima_print_digest(m, buf_ptr, buflen);
 		break;
 	case DATA_FMT_STRING:
 		seq_printf(m, "%s", buf_ptr);
 		break;
 	default:
 		break;
 	}
 }

 static void ima_show_template_data_binary(struct seq_file *m,
 					  enum ima_show_type show,
 					  enum data_formats datafmt,
 					  struct ima_field_data *field_data)
 {
 	u32 len = (show == IMA_SHOW_BINARY_OLD_STRING_FMT) ?
 	    strlen(field_data->data) : field_data->len;

 	if (show != IMA_SHOW_BINARY_NO_FIELD_LEN)
 		ima_putc(m, &len, sizeof(len));

 	if (!len)
 		return;

 	ima_putc(m, field_data->data, len);
 }

 static void ima_show_template_field_data(struct seq_file *m,
 					 enum ima_show_type show,
 					 enum data_formats datafmt,
 					 struct ima_field_data *field_data)
 {
 	switch (show) {
 	case IMA_SHOW_ASCII:
 		ima_show_template_data_ascii(m, show, datafmt, field_data);
 		break;
 	case IMA_SHOW_BINARY:
 	case IMA_SHOW_BINARY_NO_FIELD_LEN:
 	case IMA_SHOW_BINARY_OLD_STRING_FMT:
 		ima_show_template_data_binary(m, show, datafmt, field_data);
 		break;
 	default:
 		break;
 	}
 }

 void ima_show_template_digest(struct seq_file *m, enum ima_show_type show,
 			      struct ima_field_data *field_data)
 {
 	ima_show_template_field_data(m, show, DATA_FMT_DIGEST, field_data);
 }

 void ima_show_template_digest_ng(struct seq_file *m, enum ima_show_type show,
 				 struct ima_field_data *field_data)
 {
 	ima_show_template_field_data(m, show, DATA_FMT_DIGEST_WITH_ALGO,
 				     field_data);
 }

 void ima_show_template_string(struct seq_file *m, enum ima_show_type show,
 			      struct ima_field_data *field_data)
 {
 	ima_show_template_field_data(m, show, DATA_FMT_STRING, field_data);
 }

 void ima_show_template_sig(struct seq_file *m, enum ima_show_type show,
 			   struct ima_field_data *field_data)
 {
 	ima_show_template_field_data(m, show, DATA_FMT_HEX, field_data);
 }

 static int ima_eventdigest_init_common(u8 *digest, u32 digestsize, u8 hash_algo,
 				       struct ima_field_data *field_data)
 {
 	/*
 	 * digest formats:
 	 *  - DATA_FMT_DIGEST: digest
 	 *  - DATA_FMT_DIGEST_WITH_ALGO: [<hash algo>] + ':' + '\0' + digest,
 	 *    where <hash algo> is provided if the hash algoritm is not
 	 *    SHA1 or MD5
 	 */
 	u8 buffer[CRYPTO_MAX_ALG_NAME + 2 + IMA_MAX_DIGEST_SIZE] = { 0 };
 	enum data_formats fmt = DATA_FMT_DIGEST;
 	u32 offset = 0;

 	if (hash_algo < HASH_ALGO__LAST) {
 		fmt = DATA_FMT_DIGEST_WITH_ALGO;
 		offset += snprintf(buffer, CRYPTO_MAX_ALG_NAME + 1, "%s",
 				   hash_algo_name[hash_algo]);
 		buffer[offset] = ':';
 		offset += 2;
 	}

 	if (digest)
 		memcpy(buffer + offset, digest, digestsize);
 	else
 		/*
 		 * If digest is NULL, the event being recorded is a violation.
 		 * Make room for the digest by increasing the offset of
 		 * IMA_DIGEST_SIZE.
 		 */
 		offset += IMA_DIGEST_SIZE;

 	return ima_write_template_field_data(buffer, offset + digestsize,
 					     fmt, field_data);
 }

 /*
  * This function writes the digest of an event (with size limit).
  */
 int ima_eventdigest_init(struct integrity_iint_cache *iint, struct file *file,
 			 const unsigned char *filename,
 			 struct evm_ima_xattr_data *xattr_value, int xattr_len,
 			 struct ima_field_data *field_data)
 {
 	struct {
 		struct ima_digest_data hdr;
 		char digest[IMA_MAX_DIGEST_SIZE];
 	} hash;
 	u8 *cur_digest = NULL;
 	u32 cur_digestsize = 0;
 	struct inode *inode;
 	int result;

 	memset(&hash, 0, sizeof(hash));

 	if (!iint)		/* recording a violation. */
 		goto out;

 	if (ima_template_hash_algo_allowed(iint->ima_hash->algo)) {
 		cur_digest = iint->ima_hash->digest;
 		cur_digestsize = iint->ima_hash->length;
 		goto out;
 	}

 	if (!file)		/* missing info to re-calculate the digest */
 		return -EINVAL;

 	inode = file_inode(file);
 	hash.hdr.algo = ima_template_hash_algo_allowed(ima_hash_algo) ?
 	    ima_hash_algo : HASH_ALGO_SHA1;
 	result = ima_calc_file_hash(file, &hash.hdr);
 	if (result) {
 		integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
 				    filename, "collect_data",
 				    "failed", result, 0);
 		return result;
 	}
 	cur_digest = hash.hdr.digest;
 	cur_digestsize = hash.hdr.length;
 out:
 	return ima_eventdigest_init_common(cur_digest, cur_digestsize,
 					   HASH_ALGO__LAST, field_data);
 }

 /*
  * This function writes the digest of an event (without size limit).
  */
 int ima_eventdigest_ng_init(struct integrity_iint_cache *iint,
 			    struct file *file, const unsigned char *filename,
 			    struct evm_ima_xattr_data *xattr_value,
 			    int xattr_len, struct ima_field_data *field_data)
 {
 	u8 *cur_digest = NULL, hash_algo = HASH_ALGO_SHA1;
 	u32 cur_digestsize = 0;

 	/* If iint is NULL, we are recording a violation. */
 	if (!iint)
 		goto out;

 	cur_digest = iint->ima_hash->digest;
 	cur_digestsize = iint->ima_hash->length;

 	hash_algo = iint->ima_hash->algo;
 out:
 	return ima_eventdigest_init_common(cur_digest, cur_digestsize,
 					   hash_algo, field_data);
 }

 static int ima_eventname_init_common(struct integrity_iint_cache *iint,
 				     struct file *file,
 				     const unsigned char *filename,
 				     struct ima_field_data *field_data,
 				     bool size_limit)
 {
 	const char *cur_filename = NULL;
 	u32 cur_filename_len = 0;
 	enum data_formats fmt = size_limit ?
 	    DATA_FMT_EVENT_NAME : DATA_FMT_STRING;

 	BUG_ON(filename == NULL && file == NULL);

 	if (filename) {
 		cur_filename = filename;
 		cur_filename_len = strlen(filename);

 		if (!size_limit || cur_filename_len <= IMA_EVENT_NAME_LEN_MAX)
 			goto out;
 	}

 	if (file) {
 		cur_filename = file->f_dentry->d_name.name;
 		cur_filename_len = strlen(cur_filename);
 	} else
 		/*
 		 * Truncate filename if the latter is too long and
 		 * the file descriptor is not available.
 		 */
 		cur_filename_len = IMA_EVENT_NAME_LEN_MAX;
 out:
 	return ima_write_template_field_data(cur_filename, cur_filename_len,
 					     fmt, field_data);
 }

 /*
  * This function writes the name of an event (with size limit).
  */
 int ima_eventname_init(struct integrity_iint_cache *iint, struct file *file,
 		       const unsigned char *filename,
 		       struct evm_ima_xattr_data *xattr_value, int xattr_len,
 		       struct ima_field_data *field_data)
 {
 	return ima_eventname_init_common(iint, file, filename,
 					 field_data, true);
 }

 /*
  * This function writes the name of an event (without size limit).
  */
 int ima_eventname_ng_init(struct integrity_iint_cache *iint, struct file *file,
 			  const unsigned char *filename,
 			  struct evm_ima_xattr_data *xattr_value, int xattr_len,
 			  struct ima_field_data *field_data)
 {
 	return ima_eventname_init_common(iint, file, filename,
 					 field_data, false);
 }

 /*
  *  ima_eventsig_init - include the file signature as part of the template data
  */
 int ima_eventsig_init(struct integrity_iint_cache *iint, struct file *file,
 		      const unsigned char *filename,
 		      struct evm_ima_xattr_data *xattr_value, int xattr_len,
 		      struct ima_field_data *field_data)
 {
 	enum data_formats fmt = DATA_FMT_HEX;
 	int rc = 0;

 	if ((!xattr_value) || (xattr_value->type != EVM_IMA_XATTR_DIGSIG))
 		goto out;

 	rc = ima_write_template_field_data(xattr_value, xattr_len, fmt,
 					   field_data);
 out:
 	return rc;
 }
	/*
	* Copyright (C) 2013 Politecnico di Torino, Italy
	* TORSEC group -- http://security.polito.it
	*
	* Author: Roberto Sassu <roberto.sassu@polito.it>
	*
	* 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_template_lib.c
	* Library of supported template fields.
	*/
	#include <crypto/hash_info.h>

	#include "ima_template_lib.h"

	static bool ima_template_hash_algo_allowed(u8 algo)
	{
	if (algo == HASH_ALGO_SHA1 \|\| algo == HASH_ALGO_MD5)
	return true;

	return false;
	}

	enum data_formats {
	DATA_FMT_DIGEST = 0,
	DATA_FMT_DIGEST_WITH_ALGO,
	DATA_FMT_EVENT_NAME,
	DATA_FMT_STRING,
	DATA_FMT_HEX
	};

	static int ima_write_template_field_data(const void *data, const u32 datalen,
	enum data_formats datafmt,
	struct ima_field_data *field_data)
	{
	u8 buf, buf_ptr;
	u32 buflen;

	switch (datafmt) {
	case DATA_FMT_EVENT_NAME:
	buflen = IMA_EVENT_NAME_LEN_MAX + 1;
	break;
	case DATA_FMT_STRING:
	buflen = datalen + 1;
	break;
	default:
	buflen = datalen;
	}

	buf = kzalloc(buflen, GFP_KERNEL);
	if (!buf)
	return -ENOMEM;

	memcpy(buf, data, datalen);

	/*
	* Replace all space characters with underscore for event names and
	* strings. This avoid that, during the parsing of a measurements list,
	* filenames with spaces or that end with the suffix ' (deleted)' are
	* split into multiple template fields (the space is the delimitator
	* character for measurements lists in ASCII format).
	*/
	if (datafmt == DATA_FMT_EVENT_NAME \|\| datafmt == DATA_FMT_STRING) {
	for (buf_ptr = buf; buf_ptr - buf < datalen; buf_ptr++)
	if (*buf_ptr == ' ')
	*buf_ptr = '_';
	}

	field_data->data = buf;
	field_data->len = buflen;
	return 0;
	}

	static void ima_show_template_data_ascii(struct seq_file *m,
	enum ima_show_type show,
	enum data_formats datafmt,
	struct ima_field_data *field_data)
	{
	u8 *buf_ptr = field_data->data, buflen = field_data->len;

	switch (datafmt) {
	case DATA_FMT_DIGEST_WITH_ALGO:
	buf_ptr = strnchr(field_data->data, buflen, ':');
	if (buf_ptr != field_data->data)
	seq_printf(m, "%s", field_data->data);

	/* skip ':' and '\0' */
	buf_ptr += 2;
	buflen -= buf_ptr - field_data->data;
	case DATA_FMT_DIGEST:
	case DATA_FMT_HEX:
	if (!buflen)
	break;
	ima_print_digest(m, buf_ptr, buflen);
	break;
	case DATA_FMT_STRING:
	seq_printf(m, "%s", buf_ptr);
	break;
	default:
	break;
	}
	}

	static void ima_show_template_data_binary(struct seq_file *m,
	enum ima_show_type show,
	enum data_formats datafmt,
	struct ima_field_data *field_data)
	{
	u32 len = (show == IMA_SHOW_BINARY_OLD_STRING_FMT) ?
	strlen(field_data->data) : field_data->len;

	if (show != IMA_SHOW_BINARY_NO_FIELD_LEN)
	ima_putc(m, &len, sizeof(len));

	if (!len)
	return;

	ima_putc(m, field_data->data, len);
	}

	static void ima_show_template_field_data(struct seq_file *m,
	enum ima_show_type show,
	enum data_formats datafmt,
	struct ima_field_data *field_data)
	{
	switch (show) {
	case IMA_SHOW_ASCII:
	ima_show_template_data_ascii(m, show, datafmt, field_data);
	break;
	case IMA_SHOW_BINARY:
	case IMA_SHOW_BINARY_NO_FIELD_LEN:
	case IMA_SHOW_BINARY_OLD_STRING_FMT:
	ima_show_template_data_binary(m, show, datafmt, field_data);
	break;
	default:
	break;
	}
	}

	void ima_show_template_digest(struct seq_file *m, enum ima_show_type show,
	struct ima_field_data *field_data)
	{
	ima_show_template_field_data(m, show, DATA_FMT_DIGEST, field_data);
	}

	void ima_show_template_digest_ng(struct seq_file *m, enum ima_show_type show,
	struct ima_field_data *field_data)
	{
	ima_show_template_field_data(m, show, DATA_FMT_DIGEST_WITH_ALGO,
	field_data);
	}

	void ima_show_template_string(struct seq_file *m, enum ima_show_type show,
	struct ima_field_data *field_data)
	{
	ima_show_template_field_data(m, show, DATA_FMT_STRING, field_data);
	}

	void ima_show_template_sig(struct seq_file *m, enum ima_show_type show,
	struct ima_field_data *field_data)
	{
	ima_show_template_field_data(m, show, DATA_FMT_HEX, field_data);
	}

	static int ima_eventdigest_init_common(u8 *digest, u32 digestsize, u8 hash_algo,
	struct ima_field_data *field_data)
	{
	/*
	* digest formats:
	* - DATA_FMT_DIGEST: digest
	* - DATA_FMT_DIGEST_WITH_ALGO: [<hash algo>] + ':' + '\0' + digest,
	* where <hash algo> is provided if the hash algoritm is not
	* SHA1 or MD5
	*/
	u8 buffer[CRYPTO_MAX_ALG_NAME + 2 + IMA_MAX_DIGEST_SIZE] = { 0 };
	enum data_formats fmt = DATA_FMT_DIGEST;
	u32 offset = 0;

	if (hash_algo < HASH_ALGO__LAST) {
	fmt = DATA_FMT_DIGEST_WITH_ALGO;
	offset += snprintf(buffer, CRYPTO_MAX_ALG_NAME + 1, "%s",
	hash_algo_name[hash_algo]);
	buffer[offset] = ':';
	offset += 2;
	}

	if (digest)
	memcpy(buffer + offset, digest, digestsize);
	else
	/*
	* If digest is NULL, the event being recorded is a violation.
	* Make room for the digest by increasing the offset of
	* IMA_DIGEST_SIZE.
	*/
	offset += IMA_DIGEST_SIZE;

	return ima_write_template_field_data(buffer, offset + digestsize,
	fmt, field_data);
	}

	/*
	* This function writes the digest of an event (with size limit).
	*/
	int ima_eventdigest_init(struct integrity_iint_cache iint, struct file file,
	const unsigned char *filename,
	struct evm_ima_xattr_data *xattr_value, int xattr_len,
	struct ima_field_data *field_data)
	{
	struct {
	struct ima_digest_data hdr;
	char digest[IMA_MAX_DIGEST_SIZE];
	} hash;
	u8 *cur_digest = NULL;
	u32 cur_digestsize = 0;
	struct inode *inode;
	int result;

	memset(&hash, 0, sizeof(hash));

	if (!iint) /* recording a violation. */
	goto out;

	if (ima_template_hash_algo_allowed(iint->ima_hash->algo)) {
	cur_digest = iint->ima_hash->digest;
	cur_digestsize = iint->ima_hash->length;
	goto out;
	}

	if (!file) /* missing info to re-calculate the digest */
	return -EINVAL;

	inode = file_inode(file);
	hash.hdr.algo = ima_template_hash_algo_allowed(ima_hash_algo) ?
	ima_hash_algo : HASH_ALGO_SHA1;
	result = ima_calc_file_hash(file, &hash.hdr);
	if (result) {
	integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
	filename, "collect_data",
	"failed", result, 0);
	return result;
	}
	cur_digest = hash.hdr.digest;
	cur_digestsize = hash.hdr.length;
	out:
	return ima_eventdigest_init_common(cur_digest, cur_digestsize,
	HASH_ALGO__LAST, field_data);
	}

	/*
	* This function writes the digest of an event (without size limit).
	*/
	int ima_eventdigest_ng_init(struct integrity_iint_cache *iint,
	struct file file, const unsigned char filename,
	struct evm_ima_xattr_data *xattr_value,
	int xattr_len, struct ima_field_data *field_data)
	{
	u8 *cur_digest = NULL, hash_algo = HASH_ALGO_SHA1;
	u32 cur_digestsize = 0;

	/* If iint is NULL, we are recording a violation. */
	if (!iint)
	goto out;

	cur_digest = iint->ima_hash->digest;
	cur_digestsize = iint->ima_hash->length;

	hash_algo = iint->ima_hash->algo;
	out:
	return ima_eventdigest_init_common(cur_digest, cur_digestsize,
	hash_algo, field_data);
	}

	static int ima_eventname_init_common(struct integrity_iint_cache *iint,
	struct file *file,
	const unsigned char *filename,
	struct ima_field_data *field_data,
	bool size_limit)
	{
	const char *cur_filename = NULL;
	u32 cur_filename_len = 0;
	enum data_formats fmt = size_limit ?
	DATA_FMT_EVENT_NAME : DATA_FMT_STRING;

	BUG_ON(filename == NULL && file == NULL);

	if (filename) {
	cur_filename = filename;
	cur_filename_len = strlen(filename);

	if (!size_limit \|\| cur_filename_len <= IMA_EVENT_NAME_LEN_MAX)
	goto out;
	}

	if (file) {
	cur_filename = file->f_dentry->d_name.name;
	cur_filename_len = strlen(cur_filename);
	} else
	/*
	* Truncate filename if the latter is too long and
	* the file descriptor is not available.
	*/
	cur_filename_len = IMA_EVENT_NAME_LEN_MAX;
	out:
	return ima_write_template_field_data(cur_filename, cur_filename_len,
	fmt, field_data);
	}

	/*
	* This function writes the name of an event (with size limit).
	*/
	int ima_eventname_init(struct integrity_iint_cache iint, struct file file,
	const unsigned char *filename,
	struct evm_ima_xattr_data *xattr_value, int xattr_len,
	struct ima_field_data *field_data)
	{
	return ima_eventname_init_common(iint, file, filename,
	field_data, true);
	}

	/*
	* This function writes the name of an event (without size limit).
	*/
	int ima_eventname_ng_init(struct integrity_iint_cache iint, struct file file,
	const unsigned char *filename,
	struct evm_ima_xattr_data *xattr_value, int xattr_len,
	struct ima_field_data *field_data)
	{
	return ima_eventname_init_common(iint, file, filename,
	field_data, false);
	}

	/*
	* ima_eventsig_init - include the file signature as part of the template data
	*/
	int ima_eventsig_init(struct integrity_iint_cache iint, struct file file,
	const unsigned char *filename,
	struct evm_ima_xattr_data *xattr_value, int xattr_len,
	struct ima_field_data *field_data)
	{
	enum data_formats fmt = DATA_FMT_HEX;
	int rc = 0;

	if ((!xattr_value) \|\| (xattr_value->type != EVM_IMA_XATTR_DIGSIG))
	goto out;

	rc = ima_write_template_field_data(xattr_value, xattr_len, fmt,
	field_data);
	out:
	return rc;
	}