1 files changed, 337 insertions, 0 deletions
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
new file mode 100644
index 000000000..b8a27c505
--- /dev/null
+++ b/security/integrity/ima/ima_api.c
@@ -0,0 +1,337 @@
+/*
+ * 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"
+
+/*
+ * ima_free_template_entry - free an existing template entry
+ */
+void ima_free_template_entry(struct ima_template_entry *entry)
+{
+	int i;
+
+	for (i = 0; i < entry->template_desc->num_fields; i++)
+		kfree(entry->template_data[i].data);
+
+	kfree(entry);
+}
+
+/*
+ * ima_alloc_init_template - create and initialize a new template entry
+ */
+int ima_alloc_init_template(struct integrity_iint_cache *iint,
+			    struct file *file, const unsigned char *filename,
+			    struct evm_ima_xattr_data *xattr_value,
+			    int xattr_len, struct ima_template_entry **entry)
+{
+	struct ima_template_desc *template_desc = ima_template_desc_current();
+	int i, result = 0;
+
+	*entry = kzalloc(sizeof(**entry) + template_desc->num_fields *
+			 sizeof(struct ima_field_data), GFP_NOFS);
+	if (!*entry)
+		return -ENOMEM;
+
+	(*entry)->template_desc = template_desc;
+	for (i = 0; i < template_desc->num_fields; i++) {
+		struct ima_template_field *field = template_desc->fields[i];
+		u32 len;
+
+		result = field->field_init(iint, file, filename,
+					   xattr_value, xattr_len,
+					   &((*entry)->template_data[i]));
+		if (result != 0)
+			goto out;
+
+		len = (*entry)->template_data[i].len;
+		(*entry)->template_data_len += sizeof(len);
+		(*entry)->template_data_len += len;
+	}
+	return 0;
+out:
+	ima_free_template_entry(*entry);
+	*entry = NULL;
+	return result;
+}
+
+/*
+ * 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)
+{
+	static const char op[] = "add_template_measure";
+	static const char audit_cause[] = "hashing_error";
+	char *template_name = entry->template_desc->name;
+	int result;
+	struct {
+		struct ima_digest_data hdr;
+		char digest[TPM_DIGEST_SIZE];
+	} hash;
+
+	if (!violation) {
+		int num_fields = entry->template_desc->num_fields;
+
+		/* this function uses default algo */
+		hash.hdr.algo = HASH_ALGO_SHA1;
+		result = ima_calc_field_array_hash(&entry->template_data[0],
+						   entry->template_desc,
+						   num_fields, &hash.hdr);
+		if (result < 0) {
+			integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
+					    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_inode(file);
+	int violation = 1;
+	int result;
+
+	/* can overflow, only indicator */
+	atomic_long_inc(&ima_htable.violations);
+
+	result = ima_alloc_init_template(NULL, file, filename,
+					 NULL, 0, &entry);
+	if (result < 0) {
+		result = -ENOMEM;
+		goto err_out;
+	}
+	result = ima_store_template(entry, violation, inode, filename);
+	if (result < 0)
+		ima_free_template_entry(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;
+
+	flags &= ima_policy_flag;
+
+	return ima_match_policy(inode, function, mask, flags);
+}
+
+/*
+ * 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)
+{
+	const char *audit_cause = "failed";
+	struct inode *inode = file_inode(file);
+	const char *filename = file->f_path.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_path.dentry, xattr_value);
+
+	if (!(iint->flags & IMA_COLLECTED)) {
+		u64 i_version = file_inode(file)->i_version;
+
+		if (file->f_flags & O_DIRECT) {
+			audit_cause = "failed(directio)";
+			result = -EACCES;
+			goto out;
+		}
+
+		/* 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;
+		}
+	}
+out:
+	if (result)
+		integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
+				    filename, "collect_data", audit_cause,
+				    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,
+			   struct evm_ima_xattr_data *xattr_value,
+			   int xattr_len)
+{
+	static const char op[] = "add_template_measure";
+	static 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;
+
+	result = ima_alloc_init_template(iint, file, filename,
+					 xattr_value, xattr_len, &entry);
+	if (result < 0) {
+		integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
+				    op, audit_cause, result, 0);
+		return;
+	}
+
+	result = ima_store_template(entry, violation, inode, filename);
+	if (!result || result == -EEXIST)
+		iint->flags |= IMA_MEASURED;
+	if (result < 0)
+		ima_free_template_entry(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];
+	const char *algo_name = hash_algo_name[iint->ima_hash->algo];
+	char algo_hash[sizeof(hash) + strlen(algo_name) + 2];
+	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=");
+	snprintf(algo_hash, sizeof(algo_hash), "%s:%s", algo_name, hash);
+	audit_log_untrustedstring(ab, algo_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;
+
+	*pathbuf = __getname();
+	if (*pathbuf) {
+		pathname = d_absolute_path(path, *pathbuf, PATH_MAX);
+		if (IS_ERR(pathname)) {
+			__putname(*pathbuf);
+			*pathbuf = NULL;
+			pathname = NULL;
+		}
+	}
+	return pathname ?: (const char *)path->dentry->d_name.name;
+}