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linux-next/security/integrity/digsig.c
Dmitry Kasatkin 72e1eed8ab integrity: prevent loading untrusted certificates on the IMA trusted keyring
If IMA_LOAD_X509 is enabled, either directly or indirectly via
IMA_APPRAISE_SIGNED_INIT, certificates are loaded onto the IMA
trusted keyring by the kernel via key_create_or_update(). When
the KEY_ALLOC_TRUSTED flag is provided, certificates are loaded
without first verifying the certificate is properly signed by a
trusted key on the system keyring.  This patch removes the
KEY_ALLOC_TRUSTED flag.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
Cc:  <stable@vger.kernel.org> # 3.19+
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2015-10-09 15:31:18 -04:00

121 lines
2.7 KiB
C

/*
* Copyright (C) 2011 Intel Corporation
*
* Author:
* Dmitry Kasatkin <dmitry.kasatkin@intel.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.
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/cred.h>
#include <linux/key-type.h>
#include <linux/digsig.h>
#include "integrity.h"
static struct key *keyring[INTEGRITY_KEYRING_MAX];
static const char *keyring_name[INTEGRITY_KEYRING_MAX] = {
"_evm",
"_module",
#ifndef CONFIG_IMA_TRUSTED_KEYRING
"_ima",
#else
".ima",
#endif
};
int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
const char *digest, int digestlen)
{
if (id >= INTEGRITY_KEYRING_MAX)
return -EINVAL;
if (!keyring[id]) {
keyring[id] =
request_key(&key_type_keyring, keyring_name[id], NULL);
if (IS_ERR(keyring[id])) {
int err = PTR_ERR(keyring[id]);
pr_err("no %s keyring: %d\n", keyring_name[id], err);
keyring[id] = NULL;
return err;
}
}
switch (sig[1]) {
case 1:
/* v1 API expect signature without xattr type */
return digsig_verify(keyring[id], sig + 1, siglen - 1,
digest, digestlen);
case 2:
return asymmetric_verify(keyring[id], sig, siglen,
digest, digestlen);
}
return -EOPNOTSUPP;
}
int __init integrity_init_keyring(const unsigned int id)
{
const struct cred *cred = current_cred();
int err = 0;
keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0),
KGIDT_INIT(0), cred,
((KEY_POS_ALL & ~KEY_POS_SETATTR) |
KEY_USR_VIEW | KEY_USR_READ |
KEY_USR_WRITE | KEY_USR_SEARCH),
KEY_ALLOC_NOT_IN_QUOTA, NULL);
if (!IS_ERR(keyring[id]))
set_bit(KEY_FLAG_TRUSTED_ONLY, &keyring[id]->flags);
else {
err = PTR_ERR(keyring[id]);
pr_info("Can't allocate %s keyring (%d)\n",
keyring_name[id], err);
keyring[id] = NULL;
}
return err;
}
int __init integrity_load_x509(const unsigned int id, const char *path)
{
key_ref_t key;
char *data;
int rc;
if (!keyring[id])
return -EINVAL;
rc = integrity_read_file(path, &data);
if (rc < 0)
return rc;
key = key_create_or_update(make_key_ref(keyring[id], 1),
"asymmetric",
NULL,
data,
rc,
((KEY_POS_ALL & ~KEY_POS_SETATTR) |
KEY_USR_VIEW | KEY_USR_READ),
KEY_ALLOC_NOT_IN_QUOTA);
if (IS_ERR(key)) {
rc = PTR_ERR(key);
pr_err("Problem loading X.509 certificate (%d): %s\n",
rc, path);
} else {
pr_notice("Loaded X.509 cert '%s': %s\n",
key_ref_to_ptr(key)->description, path);
key_ref_put(key);
}
kfree(data);
return 0;
}