06cca51107
In preparation for removing the 'integrity' LSM, move
integrity_kernel_module_request() to IMA, and rename it to
ima_kernel_module_request(). Rewrite the function documentation, to explain
better what the problem is.
Compile it conditionally if CONFIG_INTEGRITY_ASYMMETRIC_KEYS is enabled,
and call it from security.c (removed afterwards with the move of IMA to the
LSM infrastructure).
Adding this hook cannot be avoided, since IMA has no control on the flags
passed to crypto_alloc_sig() in public_key_verify_signature(), and thus
cannot pass CRYPTO_NOLOAD, which solved the problem for EVM hashing with
commit e2861fa716 ("evm: Don't deadlock if a crypto algorithm is
unavailable").
EVM alone does not need to implement this hook, first because there is no
mutex to deadlock, and second because even if it had it, there should be a
recursive call. However, since verification from EVM can be initiated only
by setting inode metadata, deadlock would occur if modprobe would do the
same while loading a kernel module (which is unlikely).
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Acked-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
135 lines
2.9 KiB
C
135 lines
2.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2013 Intel Corporation
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*
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* Author:
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* Dmitry Kasatkin <dmitry.kasatkin@intel.com>
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*/
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#include <linux/err.h>
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#include <linux/ratelimit.h>
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#include <linux/key-type.h>
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#include <crypto/public_key.h>
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#include <crypto/hash_info.h>
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#include <keys/asymmetric-type.h>
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#include <keys/system_keyring.h>
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#include "integrity.h"
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/*
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* Request an asymmetric key.
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*/
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static struct key *request_asymmetric_key(struct key *keyring, uint32_t keyid)
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{
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struct key *key;
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char name[12];
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sprintf(name, "id:%08x", keyid);
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pr_debug("key search: \"%s\"\n", name);
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key = get_ima_blacklist_keyring();
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if (key) {
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key_ref_t kref;
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kref = keyring_search(make_key_ref(key, 1),
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&key_type_asymmetric, name, true);
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if (!IS_ERR(kref)) {
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pr_err("Key '%s' is in ima_blacklist_keyring\n", name);
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return ERR_PTR(-EKEYREJECTED);
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}
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}
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if (keyring) {
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/* search in specific keyring */
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key_ref_t kref;
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kref = keyring_search(make_key_ref(keyring, 1),
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&key_type_asymmetric, name, true);
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if (IS_ERR(kref))
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key = ERR_CAST(kref);
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else
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key = key_ref_to_ptr(kref);
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} else {
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key = request_key(&key_type_asymmetric, name, NULL);
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}
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if (IS_ERR(key)) {
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if (keyring)
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pr_err_ratelimited("Request for unknown key '%s' in '%s' keyring. err %ld\n",
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name, keyring->description,
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PTR_ERR(key));
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else
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pr_err_ratelimited("Request for unknown key '%s' err %ld\n",
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name, PTR_ERR(key));
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switch (PTR_ERR(key)) {
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/* Hide some search errors */
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case -EACCES:
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case -ENOTDIR:
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case -EAGAIN:
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return ERR_PTR(-ENOKEY);
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default:
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return key;
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}
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}
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pr_debug("%s() = 0 [%x]\n", __func__, key_serial(key));
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return key;
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}
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int asymmetric_verify(struct key *keyring, const char *sig,
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int siglen, const char *data, int datalen)
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{
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struct public_key_signature pks;
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struct signature_v2_hdr *hdr = (struct signature_v2_hdr *)sig;
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const struct public_key *pk;
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struct key *key;
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int ret;
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if (siglen <= sizeof(*hdr))
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return -EBADMSG;
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siglen -= sizeof(*hdr);
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if (siglen != be16_to_cpu(hdr->sig_size))
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return -EBADMSG;
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if (hdr->hash_algo >= HASH_ALGO__LAST)
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return -ENOPKG;
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key = request_asymmetric_key(keyring, be32_to_cpu(hdr->keyid));
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if (IS_ERR(key))
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return PTR_ERR(key);
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memset(&pks, 0, sizeof(pks));
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pks.hash_algo = hash_algo_name[hdr->hash_algo];
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pk = asymmetric_key_public_key(key);
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pks.pkey_algo = pk->pkey_algo;
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if (!strcmp(pk->pkey_algo, "rsa")) {
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pks.encoding = "pkcs1";
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} else if (!strncmp(pk->pkey_algo, "ecdsa-", 6)) {
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/* edcsa-nist-p192 etc. */
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pks.encoding = "x962";
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} else if (!strcmp(pk->pkey_algo, "ecrdsa") ||
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!strcmp(pk->pkey_algo, "sm2")) {
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pks.encoding = "raw";
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} else {
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ret = -ENOPKG;
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goto out;
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}
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pks.digest = (u8 *)data;
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pks.digest_size = datalen;
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pks.s = hdr->sig;
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pks.s_size = siglen;
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ret = verify_signature(key, &pks);
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out:
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key_put(key);
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pr_debug("%s() = %d\n", __func__, ret);
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return ret;
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}
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