security/integrity/ima/ima_appraise.c - kernel/quantenna - Git at Google

 /*
  * Copyright (C) 2011 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.
  */
 #include <linux/module.h>
 #include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/xattr.h>
 #include <linux/magic.h>
 #include <linux/ima.h>
 #include <linux/evm.h>

 #include "ima.h"

 static int __init default_appraise_setup(char *str)
 {
 	if (strncmp(str, "off", 3) == 0)
 		ima_appraise = 0;
 	else if (strncmp(str, "log", 3) == 0)
 		ima_appraise = IMA_APPRAISE_LOG;
 	else if (strncmp(str, "fix", 3) == 0)
 		ima_appraise = IMA_APPRAISE_FIX;
 	return 1;
 }

 __setup("ima_appraise=", default_appraise_setup);

 /*
  * ima_must_appraise - set appraise flag
  *
  * Return 1 to appraise
  */
 int ima_must_appraise(struct inode *inode, int mask, enum ima_hooks func)
 {
 	if (!ima_appraise)
 		return 0;

 	return ima_match_policy(inode, func, mask, IMA_APPRAISE);
 }

 static int ima_fix_xattr(struct dentry *dentry,
 			 struct integrity_iint_cache *iint)
 {
 	int rc, offset;
 	u8 algo = iint->ima_hash->algo;

 	if (algo <= HASH_ALGO_SHA1) {
 		offset = 1;
 		iint->ima_hash->xattr.sha1.type = IMA_XATTR_DIGEST;
 	} else {
 		offset = 0;
 		iint->ima_hash->xattr.ng.type = IMA_XATTR_DIGEST_NG;
 		iint->ima_hash->xattr.ng.algo = algo;
 	}
 	rc = __vfs_setxattr_noperm(dentry, XATTR_NAME_IMA,
 				   &iint->ima_hash->xattr.data[offset],
 				   (sizeof(iint->ima_hash->xattr) - offset) +
 				   iint->ima_hash->length, 0);
 	return rc;
 }

 /* Return specific func appraised cached result */
 enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint,
 					   enum ima_hooks func)
 {
 	switch (func) {
 	case MMAP_CHECK:
 		return iint->ima_mmap_status;
 	case BPRM_CHECK:
 		return iint->ima_bprm_status;
 	case FILE_CHECK:
 	case POST_SETATTR:
 		return iint->ima_file_status;
 	case MODULE_CHECK ... MAX_CHECK - 1:
 	default:
 		return iint->ima_read_status;
 	}
 }

 static void ima_set_cache_status(struct integrity_iint_cache *iint,
 				 enum ima_hooks func,
 				 enum integrity_status status)
 {
 	switch (func) {
 	case MMAP_CHECK:
 		iint->ima_mmap_status = status;
 		break;
 	case BPRM_CHECK:
 		iint->ima_bprm_status = status;
 		break;
 	case FILE_CHECK:
 	case POST_SETATTR:
 		iint->ima_file_status = status;
 		break;
 	case MODULE_CHECK ... MAX_CHECK - 1:
 	default:
 		iint->ima_read_status = status;
 		break;
 	}
 }

 static void ima_cache_flags(struct integrity_iint_cache *iint,
 			     enum ima_hooks func)
 {
 	switch (func) {
 	case MMAP_CHECK:
 		iint->flags |= (IMA_MMAP_APPRAISED | IMA_APPRAISED);
 		break;
 	case BPRM_CHECK:
 		iint->flags |= (IMA_BPRM_APPRAISED | IMA_APPRAISED);
 		break;
 	case FILE_CHECK:
 	case POST_SETATTR:
 		iint->flags |= (IMA_FILE_APPRAISED | IMA_APPRAISED);
 		break;
 	case MODULE_CHECK ... MAX_CHECK - 1:
 	default:
 		iint->flags |= (IMA_READ_APPRAISED | IMA_APPRAISED);
 		break;
 	}
 }

 enum hash_algo ima_get_hash_algo(struct evm_ima_xattr_data *xattr_value,
 				 int xattr_len)
 {
 	struct signature_v2_hdr *sig;

 	if (!xattr_value || xattr_len < 2)
 		/* return default hash algo */
 		return ima_hash_algo;

 	switch (xattr_value->type) {
 	case EVM_IMA_XATTR_DIGSIG:
 		sig = (typeof(sig))xattr_value;
 		if (sig->version != 2 || xattr_len <= sizeof(*sig))
 			return ima_hash_algo;
 		return sig->hash_algo;
 		break;
 	case IMA_XATTR_DIGEST_NG:
 		return xattr_value->digest[0];
 		break;
 	case IMA_XATTR_DIGEST:
 		/* this is for backward compatibility */
 		if (xattr_len == 21) {
 			unsigned int zero = 0;
 			if (!memcmp(&xattr_value->digest[16], &zero, 4))
 				return HASH_ALGO_MD5;
 			else
 				return HASH_ALGO_SHA1;
 		} else if (xattr_len == 17)
 			return HASH_ALGO_MD5;
 		break;
 	}

 	/* return default hash algo */
 	return ima_hash_algo;
 }

 int ima_read_xattr(struct dentry *dentry,
 		   struct evm_ima_xattr_data **xattr_value)
 {
 	struct inode *inode = d_backing_inode(dentry);

 	if (!inode->i_op->getxattr)
 		return 0;

 	return vfs_getxattr_alloc(dentry, XATTR_NAME_IMA, (char **)xattr_value,
 				  0, GFP_NOFS);
 }

 /*
  * ima_appraise_measurement - appraise file measurement
  *
  * Call evm_verifyxattr() to verify the integrity of 'security.ima'.
  * Assuming success, compare the xattr hash with the collected measurement.
  *
  * Return 0 on success, error code otherwise
  */
 int ima_appraise_measurement(enum ima_hooks func,
 			     struct integrity_iint_cache *iint,
 			     struct file *file, const unsigned char *filename,
 			     struct evm_ima_xattr_data *xattr_value,
 			     int xattr_len, int opened)
 {
 	static const char op[] = "appraise_data";
 	char *cause = "unknown";
 	struct dentry *dentry = file->f_path.dentry;
 	struct inode *inode = d_backing_inode(dentry);
 	enum integrity_status status = INTEGRITY_UNKNOWN;
 	int rc = xattr_len, hash_start = 0;

 	if (!inode->i_op->getxattr)
 		return INTEGRITY_UNKNOWN;

 	if (rc <= 0) {
 		if (rc && rc != -ENODATA)
 			goto out;

 		cause = "missing-hash";
 		status = INTEGRITY_NOLABEL;
 		if (opened & FILE_CREATED) {
 			iint->flags |= IMA_NEW_FILE;
 			status = INTEGRITY_PASS;
 		}
 		goto out;
 	}

 	status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value, rc, iint);
 	if ((status != INTEGRITY_PASS) && (status != INTEGRITY_UNKNOWN)) {
 		if ((status == INTEGRITY_NOLABEL)
 		    || (status == INTEGRITY_NOXATTRS))
 			cause = "missing-HMAC";
 		else if (status == INTEGRITY_FAIL)
 			cause = "invalid-HMAC";
 		goto out;
 	}
 	switch (xattr_value->type) {
 	case IMA_XATTR_DIGEST_NG:
 		/* first byte contains algorithm id */
 		hash_start = 1;
 	case IMA_XATTR_DIGEST:
 		if (iint->flags & IMA_DIGSIG_REQUIRED) {
 			cause = "IMA-signature-required";
 			status = INTEGRITY_FAIL;
 			break;
 		}
 		if (xattr_len - sizeof(xattr_value->type) - hash_start >=
 				iint->ima_hash->length)
 			/* xattr length may be longer. md5 hash in previous
 			   version occupied 20 bytes in xattr, instead of 16
 			 */
 			rc = memcmp(&xattr_value->digest[hash_start],
 				    iint->ima_hash->digest,
 				    iint->ima_hash->length);
 		else
 			rc = -EINVAL;
 		if (rc) {
 			cause = "invalid-hash";
 			status = INTEGRITY_FAIL;
 			break;
 		}
 		status = INTEGRITY_PASS;
 		break;
 	case EVM_IMA_XATTR_DIGSIG:
 		iint->flags |= IMA_DIGSIG;
 		rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA,
 					     (const char *)xattr_value, rc,
 					     iint->ima_hash->digest,
 					     iint->ima_hash->length);
 		if (rc == -EOPNOTSUPP) {
 			status = INTEGRITY_UNKNOWN;
 		} else if (rc) {
 			cause = "invalid-signature";
 			status = INTEGRITY_FAIL;
 		} else {
 			status = INTEGRITY_PASS;
 		}
 		break;
 	default:
 		status = INTEGRITY_UNKNOWN;
 		cause = "unknown-ima-data";
 		break;
 	}

 out:
 	if (status != INTEGRITY_PASS) {
 		if ((ima_appraise & IMA_APPRAISE_FIX) &&
 		    (!xattr_value ||
 		     xattr_value->type != EVM_IMA_XATTR_DIGSIG)) {
 			if (!ima_fix_xattr(dentry, iint))
 				status = INTEGRITY_PASS;
 		} else if ((inode->i_size == 0) &&
 			   (iint->flags & IMA_NEW_FILE) &&
 			   (xattr_value &&
 			    xattr_value->type == EVM_IMA_XATTR_DIGSIG)) {
 			status = INTEGRITY_PASS;
 		}
 		integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename,
 				    op, cause, rc, 0);
 	} else {
 		ima_cache_flags(iint, func);
 	}
 	ima_set_cache_status(iint, func, status);
 	return status;
 }

 /*
  * ima_update_xattr - update 'security.ima' hash value
  */
 void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
 {
 	struct dentry *dentry = file->f_path.dentry;
 	int rc = 0;

 	/* do not collect and update hash for digital signatures */
 	if (iint->flags & IMA_DIGSIG)
 		return;

 	rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo);
 	if (rc < 0)
 		return;

 	ima_fix_xattr(dentry, iint);
 }

 /**
  * ima_inode_post_setattr - reflect file metadata changes
  * @dentry: pointer to the affected dentry
  *
  * Changes to a dentry's metadata might result in needing to appraise.
  *
  * This function is called from notify_change(), which expects the caller
  * to lock the inode's i_mutex.
  */
 void ima_inode_post_setattr(struct dentry *dentry)
 {
 	struct inode *inode = d_backing_inode(dentry);
 	struct integrity_iint_cache *iint;
 	int must_appraise, rc;

 	if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode)
 	    || !inode->i_op->removexattr)
 		return;

 	must_appraise = ima_must_appraise(inode, MAY_ACCESS, POST_SETATTR);
 	iint = integrity_iint_find(inode);
 	if (iint) {
 		iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
 				 IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
 				 IMA_ACTION_RULE_FLAGS);
 		if (must_appraise)
 			iint->flags |= IMA_APPRAISE;
 	}
 	if (!must_appraise)
 		rc = inode->i_op->removexattr(dentry, XATTR_NAME_IMA);
 	return;
 }

 /*
  * ima_protect_xattr - protect 'security.ima'
  *
  * Ensure that not just anyone can modify or remove 'security.ima'.
  */
 static int ima_protect_xattr(struct dentry *dentry, const char *xattr_name,
 			     const void *xattr_value, size_t xattr_value_len)
 {
 	if (strcmp(xattr_name, XATTR_NAME_IMA) == 0) {
 		if (!capable(CAP_SYS_ADMIN))
 			return -EPERM;
 		return 1;
 	}
 	return 0;
 }

 static void ima_reset_appraise_flags(struct inode *inode, int digsig)
 {
 	struct integrity_iint_cache *iint;

 	if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode))
 		return;

 	iint = integrity_iint_find(inode);
 	if (!iint)
 		return;

 	iint->flags &= ~IMA_DONE_MASK;
 	if (digsig)
 		iint->flags |= IMA_DIGSIG;
 	return;
 }

 int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
 		       const void *xattr_value, size_t xattr_value_len)
 {
 	const struct evm_ima_xattr_data *xvalue = xattr_value;
 	int result;

 	result = ima_protect_xattr(dentry, xattr_name, xattr_value,
 				   xattr_value_len);
 	if (result == 1) {
 		bool digsig;

 		if (!xattr_value_len || (xvalue->type >= IMA_XATTR_LAST))
 			return -EINVAL;
 		digsig = (xvalue->type == EVM_IMA_XATTR_DIGSIG);
 		if (!digsig && (ima_appraise & IMA_APPRAISE_ENFORCE))
 			return -EPERM;
 		ima_reset_appraise_flags(d_backing_inode(dentry), digsig);
 		result = 0;
 	}
 	return result;
 }

 int ima_inode_removexattr(struct dentry *dentry, const char *xattr_name)
 {
 	int result;

 	result = ima_protect_xattr(dentry, xattr_name, NULL, 0);
 	if (result == 1) {
 		ima_reset_appraise_flags(d_backing_inode(dentry), 0);
 		result = 0;
 	}
 	return result;
 }
	/*
	* Copyright (C) 2011 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.
	*/
	#include <linux/module.h>
	#include <linux/file.h>
	#include <linux/fs.h>
	#include <linux/xattr.h>
	#include <linux/magic.h>
	#include <linux/ima.h>
	#include <linux/evm.h>

	#include "ima.h"

	static int __init default_appraise_setup(char *str)
	{
	if (strncmp(str, "off", 3) == 0)
	ima_appraise = 0;
	else if (strncmp(str, "log", 3) == 0)
	ima_appraise = IMA_APPRAISE_LOG;
	else if (strncmp(str, "fix", 3) == 0)
	ima_appraise = IMA_APPRAISE_FIX;
	return 1;
	}

	__setup("ima_appraise=", default_appraise_setup);

	/*
	* ima_must_appraise - set appraise flag
	*
	* Return 1 to appraise
	*/
	int ima_must_appraise(struct inode *inode, int mask, enum ima_hooks func)
	{
	if (!ima_appraise)
	return 0;

	return ima_match_policy(inode, func, mask, IMA_APPRAISE);
	}

	static int ima_fix_xattr(struct dentry *dentry,
	struct integrity_iint_cache *iint)
	{
	int rc, offset;
	u8 algo = iint->ima_hash->algo;

	if (algo <= HASH_ALGO_SHA1) {
	offset = 1;
	iint->ima_hash->xattr.sha1.type = IMA_XATTR_DIGEST;
	} else {
	offset = 0;
	iint->ima_hash->xattr.ng.type = IMA_XATTR_DIGEST_NG;
	iint->ima_hash->xattr.ng.algo = algo;
	}
	rc = __vfs_setxattr_noperm(dentry, XATTR_NAME_IMA,
	&iint->ima_hash->xattr.data[offset],
	(sizeof(iint->ima_hash->xattr) - offset) +
	iint->ima_hash->length, 0);
	return rc;
	}

	/* Return specific func appraised cached result */
	enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint,
	enum ima_hooks func)
	{
	switch (func) {
	case MMAP_CHECK:
	return iint->ima_mmap_status;
	case BPRM_CHECK:
	return iint->ima_bprm_status;
	case FILE_CHECK:
	case POST_SETATTR:
	return iint->ima_file_status;
	case MODULE_CHECK ... MAX_CHECK - 1:
	default:
	return iint->ima_read_status;
	}
	}

	static void ima_set_cache_status(struct integrity_iint_cache *iint,
	enum ima_hooks func,
	enum integrity_status status)
	{
	switch (func) {
	case MMAP_CHECK:
	iint->ima_mmap_status = status;
	break;
	case BPRM_CHECK:
	iint->ima_bprm_status = status;
	break;
	case FILE_CHECK:
	case POST_SETATTR:
	iint->ima_file_status = status;
	break;
	case MODULE_CHECK ... MAX_CHECK - 1:
	default:
	iint->ima_read_status = status;
	break;
	}
	}

	static void ima_cache_flags(struct integrity_iint_cache *iint,
	enum ima_hooks func)
	{
	switch (func) {
	case MMAP_CHECK:
	iint->flags \|= (IMA_MMAP_APPRAISED \| IMA_APPRAISED);
	break;
	case BPRM_CHECK:
	iint->flags \|= (IMA_BPRM_APPRAISED \| IMA_APPRAISED);
	break;
	case FILE_CHECK:
	case POST_SETATTR:
	iint->flags \|= (IMA_FILE_APPRAISED \| IMA_APPRAISED);
	break;
	case MODULE_CHECK ... MAX_CHECK - 1:
	default:
	iint->flags \|= (IMA_READ_APPRAISED \| IMA_APPRAISED);
	break;
	}
	}

	enum hash_algo ima_get_hash_algo(struct evm_ima_xattr_data *xattr_value,
	int xattr_len)
	{
	struct signature_v2_hdr *sig;

	if (!xattr_value \|\| xattr_len < 2)
	/* return default hash algo */
	return ima_hash_algo;

	switch (xattr_value->type) {
	case EVM_IMA_XATTR_DIGSIG:
	sig = (typeof(sig))xattr_value;
	if (sig->version != 2 \|\| xattr_len <= sizeof(*sig))
	return ima_hash_algo;
	return sig->hash_algo;
	break;
	case IMA_XATTR_DIGEST_NG:
	return xattr_value->digest[0];
	break;
	case IMA_XATTR_DIGEST:
	/* this is for backward compatibility */
	if (xattr_len == 21) {
	unsigned int zero = 0;
	if (!memcmp(&xattr_value->digest[16], &zero, 4))
	return HASH_ALGO_MD5;
	else
	return HASH_ALGO_SHA1;
	} else if (xattr_len == 17)
	return HASH_ALGO_MD5;
	break;
	}

	/* return default hash algo */
	return ima_hash_algo;
	}

	int ima_read_xattr(struct dentry *dentry,
	struct evm_ima_xattr_data **xattr_value)
	{
	struct inode *inode = d_backing_inode(dentry);

	if (!inode->i_op->getxattr)
	return 0;

	return vfs_getxattr_alloc(dentry, XATTR_NAME_IMA, (char **)xattr_value,
	0, GFP_NOFS);
	}

	/*
	* ima_appraise_measurement - appraise file measurement
	*
	* Call evm_verifyxattr() to verify the integrity of 'security.ima'.
	* Assuming success, compare the xattr hash with the collected measurement.
	*
	* Return 0 on success, error code otherwise
	*/
	int ima_appraise_measurement(enum ima_hooks func,
	struct integrity_iint_cache *iint,
	struct file file, const unsigned char filename,
	struct evm_ima_xattr_data *xattr_value,
	int xattr_len, int opened)
	{
	static const char op[] = "appraise_data";
	char *cause = "unknown";
	struct dentry *dentry = file->f_path.dentry;
	struct inode *inode = d_backing_inode(dentry);
	enum integrity_status status = INTEGRITY_UNKNOWN;
	int rc = xattr_len, hash_start = 0;

	if (!inode->i_op->getxattr)
	return INTEGRITY_UNKNOWN;

	if (rc <= 0) {
	if (rc && rc != -ENODATA)
	goto out;

	cause = "missing-hash";
	status = INTEGRITY_NOLABEL;
	if (opened & FILE_CREATED) {
	iint->flags \|= IMA_NEW_FILE;
	status = INTEGRITY_PASS;
	}
	goto out;
	}

	status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value, rc, iint);
	if ((status != INTEGRITY_PASS) && (status != INTEGRITY_UNKNOWN)) {
	if ((status == INTEGRITY_NOLABEL)
	\|\| (status == INTEGRITY_NOXATTRS))
	cause = "missing-HMAC";
	else if (status == INTEGRITY_FAIL)
	cause = "invalid-HMAC";
	goto out;
	}
	switch (xattr_value->type) {
	case IMA_XATTR_DIGEST_NG:
	/* first byte contains algorithm id */
	hash_start = 1;
	case IMA_XATTR_DIGEST:
	if (iint->flags & IMA_DIGSIG_REQUIRED) {
	cause = "IMA-signature-required";
	status = INTEGRITY_FAIL;
	break;
	}
	if (xattr_len - sizeof(xattr_value->type) - hash_start >=
	iint->ima_hash->length)
	/* xattr length may be longer. md5 hash in previous
	version occupied 20 bytes in xattr, instead of 16
	*/
	rc = memcmp(&xattr_value->digest[hash_start],
	iint->ima_hash->digest,
	iint->ima_hash->length);
	else
	rc = -EINVAL;
	if (rc) {
	cause = "invalid-hash";
	status = INTEGRITY_FAIL;
	break;
	}
	status = INTEGRITY_PASS;
	break;
	case EVM_IMA_XATTR_DIGSIG:
	iint->flags \|= IMA_DIGSIG;
	rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA,
	(const char *)xattr_value, rc,
	iint->ima_hash->digest,
	iint->ima_hash->length);
	if (rc == -EOPNOTSUPP) {
	status = INTEGRITY_UNKNOWN;
	} else if (rc) {
	cause = "invalid-signature";
	status = INTEGRITY_FAIL;
	} else {
	status = INTEGRITY_PASS;
	}
	break;
	default:
	status = INTEGRITY_UNKNOWN;
	cause = "unknown-ima-data";
	break;
	}

	out:
	if (status != INTEGRITY_PASS) {
	if ((ima_appraise & IMA_APPRAISE_FIX) &&
	(!xattr_value \|\|
	xattr_value->type != EVM_IMA_XATTR_DIGSIG)) {
	if (!ima_fix_xattr(dentry, iint))
	status = INTEGRITY_PASS;
	} else if ((inode->i_size == 0) &&
	(iint->flags & IMA_NEW_FILE) &&
	(xattr_value &&
	xattr_value->type == EVM_IMA_XATTR_DIGSIG)) {
	status = INTEGRITY_PASS;
	}
	integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename,
	op, cause, rc, 0);
	} else {
	ima_cache_flags(iint, func);
	}
	ima_set_cache_status(iint, func, status);
	return status;
	}

	/*
	* ima_update_xattr - update 'security.ima' hash value
	*/
	void ima_update_xattr(struct integrity_iint_cache iint, struct file file)
	{
	struct dentry *dentry = file->f_path.dentry;
	int rc = 0;

	/* do not collect and update hash for digital signatures */
	if (iint->flags & IMA_DIGSIG)
	return;

	rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo);
	if (rc < 0)
	return;

	ima_fix_xattr(dentry, iint);
	}

	/**
	* ima_inode_post_setattr - reflect file metadata changes
	* @dentry: pointer to the affected dentry
	*
	* Changes to a dentry's metadata might result in needing to appraise.
	*
	* This function is called from notify_change(), which expects the caller
	* to lock the inode's i_mutex.
	*/
	void ima_inode_post_setattr(struct dentry *dentry)
	{
	struct inode *inode = d_backing_inode(dentry);
	struct integrity_iint_cache *iint;
	int must_appraise, rc;

	if (!(ima_policy_flag & IMA_APPRAISE) \|\| !S_ISREG(inode->i_mode)
	\|\| !inode->i_op->removexattr)
	return;

	must_appraise = ima_must_appraise(inode, MAY_ACCESS, POST_SETATTR);
	iint = integrity_iint_find(inode);
	if (iint) {
	iint->flags &= ~(IMA_APPRAISE \| IMA_APPRAISED \|
	IMA_APPRAISE_SUBMASK \| IMA_APPRAISED_SUBMASK \|
	IMA_ACTION_RULE_FLAGS);
	if (must_appraise)
	iint->flags \|= IMA_APPRAISE;
	}
	if (!must_appraise)
	rc = inode->i_op->removexattr(dentry, XATTR_NAME_IMA);
	return;
	}

	/*
	* ima_protect_xattr - protect 'security.ima'
	*
	* Ensure that not just anyone can modify or remove 'security.ima'.
	*/
	static int ima_protect_xattr(struct dentry dentry, const char xattr_name,
	const void *xattr_value, size_t xattr_value_len)
	{
	if (strcmp(xattr_name, XATTR_NAME_IMA) == 0) {
	if (!capable(CAP_SYS_ADMIN))
	return -EPERM;
	return 1;
	}
	return 0;
	}

	static void ima_reset_appraise_flags(struct inode *inode, int digsig)
	{
	struct integrity_iint_cache *iint;

	if (!(ima_policy_flag & IMA_APPRAISE) \|\| !S_ISREG(inode->i_mode))
	return;

	iint = integrity_iint_find(inode);
	if (!iint)
	return;

	iint->flags &= ~IMA_DONE_MASK;
	if (digsig)
	iint->flags \|= IMA_DIGSIG;
	return;
	}

	int ima_inode_setxattr(struct dentry dentry, const char xattr_name,
	const void *xattr_value, size_t xattr_value_len)
	{
	const struct evm_ima_xattr_data *xvalue = xattr_value;
	int result;

	result = ima_protect_xattr(dentry, xattr_name, xattr_value,
	xattr_value_len);
	if (result == 1) {
	bool digsig;

	if (!xattr_value_len \|\| (xvalue->type >= IMA_XATTR_LAST))
	return -EINVAL;
	digsig = (xvalue->type == EVM_IMA_XATTR_DIGSIG);
	if (!digsig && (ima_appraise & IMA_APPRAISE_ENFORCE))
	return -EPERM;
	ima_reset_appraise_flags(d_backing_inode(dentry), digsig);
	result = 0;
	}
	return result;
	}

	int ima_inode_removexattr(struct dentry dentry, const char xattr_name)
	{
	int result;

	result = ima_protect_xattr(dentry, xattr_name, NULL, 0);
	if (result == 1) {
	ima_reset_appraise_flags(d_backing_inode(dentry), 0);
	result = 0;
	}
	return result;
	}