mirror of https://gitee.com/openkylin/linux.git
378 lines
10 KiB
C
378 lines
10 KiB
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 <linux/iversion.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 ima_event_data *event_data,
|
|
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(event_data,
|
|
&((*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, int pcr)
|
|
{
|
|
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);
|
|
}
|
|
entry->pcr = pcr;
|
|
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,
|
|
struct integrity_iint_cache *iint,
|
|
const char *op, const char *cause)
|
|
{
|
|
struct ima_template_entry *entry;
|
|
struct inode *inode = file_inode(file);
|
|
struct ima_event_data event_data = {iint, file, filename, NULL, 0,
|
|
cause};
|
|
int violation = 1;
|
|
int result;
|
|
|
|
/* can overflow, only indicator */
|
|
atomic_long_inc(&ima_htable.violations);
|
|
|
|
result = ima_alloc_init_template(&event_data, &entry);
|
|
if (result < 0) {
|
|
result = -ENOMEM;
|
|
goto err_out;
|
|
}
|
|
result = ima_store_template(entry, violation, inode,
|
|
filename, CONFIG_IMA_MEASURE_PCR_IDX);
|
|
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
|
|
* @cred: pointer to credentials structure to validate
|
|
* @secid: secid of the task being validated
|
|
* @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXEC,
|
|
* MAY_APPEND)
|
|
* @func: caller identifier
|
|
* @pcr: pointer filled in if matched measure policy sets pcr=
|
|
*
|
|
* 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 | CREDS_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, const struct cred *cred, u32 secid,
|
|
int mask, enum ima_hooks func, int *pcr)
|
|
{
|
|
int flags = IMA_MEASURE | IMA_AUDIT | IMA_APPRAISE | IMA_HASH;
|
|
|
|
flags &= ima_policy_flag;
|
|
|
|
return ima_match_policy(inode, cred, secid, func, mask, flags, pcr);
|
|
}
|
|
|
|
/*
|
|
* 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, void *buf, loff_t size,
|
|
enum hash_algo algo)
|
|
{
|
|
const char *audit_cause = "failed";
|
|
struct inode *inode = file_inode(file);
|
|
const char *filename = file->f_path.dentry->d_name.name;
|
|
int result = 0;
|
|
int length;
|
|
void *tmpbuf;
|
|
u64 i_version;
|
|
struct {
|
|
struct ima_digest_data hdr;
|
|
char digest[IMA_MAX_DIGEST_SIZE];
|
|
} hash;
|
|
|
|
if (iint->flags & IMA_COLLECTED)
|
|
goto out;
|
|
|
|
/*
|
|
* Dectecting file change is based on i_version. On filesystems
|
|
* which do not support i_version, support is limited to an initial
|
|
* measurement/appraisal/audit.
|
|
*/
|
|
i_version = inode_query_iversion(inode);
|
|
hash.hdr.algo = algo;
|
|
|
|
/* Initialize hash digest to 0's in case of failure */
|
|
memset(&hash.digest, 0, sizeof(hash.digest));
|
|
|
|
if (buf)
|
|
result = ima_calc_buffer_hash(buf, size, &hash.hdr);
|
|
else
|
|
result = ima_calc_file_hash(file, &hash.hdr);
|
|
|
|
if (result && result != -EBADF && result != -EINVAL)
|
|
goto out;
|
|
|
|
length = sizeof(hash.hdr) + hash.hdr.length;
|
|
tmpbuf = krealloc(iint->ima_hash, length, GFP_NOFS);
|
|
if (!tmpbuf) {
|
|
result = -ENOMEM;
|
|
goto out;
|
|
}
|
|
|
|
iint->ima_hash = tmpbuf;
|
|
memcpy(iint->ima_hash, &hash, length);
|
|
iint->version = i_version;
|
|
|
|
/* Possibly temporary failure due to type of read (eg. O_DIRECT) */
|
|
if (!result)
|
|
iint->flags |= IMA_COLLECTED;
|
|
out:
|
|
if (result) {
|
|
if (file->f_flags & O_DIRECT)
|
|
audit_cause = "failed(directio)";
|
|
|
|
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, int pcr)
|
|
{
|
|
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;
|
|
struct ima_event_data event_data = {iint, file, filename, xattr_value,
|
|
xattr_len, NULL};
|
|
int violation = 0;
|
|
|
|
if (iint->measured_pcrs & (0x1 << pcr))
|
|
return;
|
|
|
|
result = ima_alloc_init_template(&event_data, &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, pcr);
|
|
if ((!result || result == -EEXIST) && !(file->f_flags & O_DIRECT)) {
|
|
iint->flags |= IMA_MEASURED;
|
|
iint->measured_pcrs |= (0x1 << pcr);
|
|
}
|
|
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;
|
|
const char *algo_name = hash_algo_name[iint->ima_hash->algo];
|
|
int i;
|
|
|
|
if (iint->flags & IMA_AUDITED)
|
|
return;
|
|
|
|
hash = kzalloc((iint->ima_hash->length * 2) + 1, GFP_KERNEL);
|
|
if (!hash)
|
|
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(audit_context(), GFP_KERNEL,
|
|
AUDIT_INTEGRITY_RULE);
|
|
if (!ab)
|
|
goto out;
|
|
|
|
audit_log_format(ab, "file=");
|
|
audit_log_untrustedstring(ab, filename);
|
|
audit_log_format(ab, " hash=\"%s:%s\"", algo_name, hash);
|
|
|
|
audit_log_task_info(ab, current);
|
|
audit_log_end(ab);
|
|
|
|
iint->flags |= IMA_AUDITED;
|
|
out:
|
|
kfree(hash);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* ima_d_path - return a pointer to the full pathname
|
|
*
|
|
* Attempt to return a pointer to the full pathname for use in the
|
|
* IMA measurement list, IMA audit records, and auditing logs.
|
|
*
|
|
* On failure, return a pointer to a copy of the filename, not dname.
|
|
* Returning a pointer to dname, could result in using the pointer
|
|
* after the memory has been freed.
|
|
*/
|
|
const char *ima_d_path(const struct path *path, char **pathbuf, char *namebuf)
|
|
{
|
|
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;
|
|
}
|
|
}
|
|
|
|
if (!pathname) {
|
|
strlcpy(namebuf, path->dentry->d_name.name, NAME_MAX);
|
|
pathname = namebuf;
|
|
}
|
|
|
|
return pathname;
|
|
}
|