415 lines
10 KiB
C
415 lines
10 KiB
C
|
/*
|
||
|
|
* 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, NULL);
|
||
|
|
}
|
||
|
|
|
||
|
|
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)
|
||
|
|
{
|
||
|
|
ssize_t ret;
|
||
|
|
|
||
|
|
ret = vfs_getxattr_alloc(dentry, XATTR_NAME_IMA, (char **)xattr_value,
|
||
|
|
0, GFP_NOFS);
|
||
|
|
if (ret == -EOPNOTSUPP)
|
||
|
|
ret = 0;
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* 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_dentry(file);
|
||
|
|
struct inode *inode = d_backing_inode(dentry);
|
||
|
|
enum integrity_status status = INTEGRITY_UNKNOWN;
|
||
|
|
int rc = xattr_len, hash_start = 0;
|
||
|
|
|
||
|
|
if (!(inode->i_opflags & IOP_XATTR))
|
||
|
|
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;
|
||
|
|
if ((iint->flags & IMA_NEW_FILE) &&
|
||
|
|
(!(iint->flags & IMA_DIGSIG_REQUIRED) ||
|
||
|
|
(inode->i_size == 0)))
|
||
|
|
status = INTEGRITY_PASS;
|
||
|
|
goto out;
|
||
|
|
}
|
||
|
|
|
||
|
|
status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value, rc, iint);
|
||
|
|
if ((status != INTEGRITY_PASS) &&
|
||
|
|
(status != INTEGRITY_PASS_IMMUTABLE) &&
|
||
|
|
(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;
|
||
|
|
}
|
||
|
|
clear_bit(IMA_DIGSIG, &iint->atomic_flags);
|
||
|
|
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:
|
||
|
|
set_bit(IMA_DIGSIG, &iint->atomic_flags);
|
||
|
|
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_dentry(file);
|
||
|
|
int rc = 0;
|
||
|
|
|
||
|
|
/* do not collect and update hash for digital signatures */
|
||
|
|
if (test_bit(IMA_DIGSIG, &iint->atomic_flags))
|
||
|
|
return;
|
||
|
|
|
||
|
|
if (iint->ima_file_status != INTEGRITY_PASS)
|
||
|
|
return;
|
||
|
|
|
||
|
|
rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo);
|
||
|
|
if (rc < 0)
|
||
|
|
return;
|
||
|
|
|
||
|
|
inode_lock(file_inode(file));
|
||
|
|
ima_fix_xattr(dentry, iint);
|
||
|
|
inode_unlock(file_inode(file));
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* 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;
|
||
|
|
|
||
|
|
if (!(ima_policy_flag & IMA_APPRAISE) || !S_ISREG(inode->i_mode)
|
||
|
|
|| !(inode->i_opflags & IOP_XATTR))
|
||
|
|
return;
|
||
|
|
|
||
|
|
must_appraise = ima_must_appraise(inode, MAY_ACCESS, POST_SETATTR);
|
||
|
|
if (!must_appraise)
|
||
|
|
__vfs_removexattr(dentry, XATTR_NAME_IMA);
|
||
|
|
iint = integrity_iint_find(inode);
|
||
|
|
if (iint) {
|
||
|
|
set_bit(IMA_CHANGE_ATTR, &iint->atomic_flags);
|
||
|
|
if (!must_appraise)
|
||
|
|
clear_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* 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->measured_pcrs = 0;
|
||
|
|
set_bit(IMA_CHANGE_XATTR, &iint->atomic_flags);
|
||
|
|
if (digsig)
|
||
|
|
set_bit(IMA_DIGSIG, &iint->atomic_flags);
|
||
|
|
else
|
||
|
|
clear_bit(IMA_DIGSIG, &iint->atomic_flags);
|
||
|
|
}
|
||
|
|
|
||
|
|
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) {
|
||
|
|
if (!xattr_value_len || (xvalue->type >= IMA_XATTR_LAST))
|
||
|
|
return -EINVAL;
|
||
|
|
ima_reset_appraise_flags(d_backing_inode(dentry),
|
||
|
|
(xvalue->type == EVM_IMA_XATTR_DIGSIG) ? 1 : 0);
|
||
|
|
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;
|
||
|
|
}
|