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579b2ba40e
If enabled, we fallback to the platform keyring if the trusted keyring doesn't have
the key used to sign the roothash. But if pkcs7_verify() rejects the key for other
reasons, such as usage restrictions, we do not fallback. Do so.
Follow-up for 6fce1f40e9
Suggested-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Luca Boccassi <bluca@debian.org>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
146 lines
3.4 KiB
C
146 lines
3.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2019 Microsoft Corporation.
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*
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* Author: Jaskaran Singh Khurana <jaskarankhurana@linux.microsoft.com>
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*
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*/
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#include <linux/device-mapper.h>
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#include <linux/verification.h>
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#include <keys/user-type.h>
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#include <linux/module.h>
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#include "dm-verity.h"
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#include "dm-verity-verify-sig.h"
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#define DM_VERITY_VERIFY_ERR(s) DM_VERITY_ROOT_HASH_VERIFICATION " " s
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static bool require_signatures;
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module_param(require_signatures, bool, 0444);
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MODULE_PARM_DESC(require_signatures,
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"Verify the roothash of dm-verity hash tree");
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#define DM_VERITY_IS_SIG_FORCE_ENABLED() \
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(require_signatures != false)
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bool verity_verify_is_sig_opt_arg(const char *arg_name)
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{
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return (!strcasecmp(arg_name,
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DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY));
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}
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static int verity_verify_get_sig_from_key(const char *key_desc,
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struct dm_verity_sig_opts *sig_opts)
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{
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struct key *key;
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const struct user_key_payload *ukp;
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int ret = 0;
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key = request_key(&key_type_user,
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key_desc, NULL);
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if (IS_ERR(key))
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return PTR_ERR(key);
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down_read(&key->sem);
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ukp = user_key_payload_locked(key);
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if (!ukp) {
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ret = -EKEYREVOKED;
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goto end;
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}
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sig_opts->sig = kmalloc(ukp->datalen, GFP_KERNEL);
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if (!sig_opts->sig) {
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ret = -ENOMEM;
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goto end;
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}
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sig_opts->sig_size = ukp->datalen;
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memcpy(sig_opts->sig, ukp->data, sig_opts->sig_size);
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end:
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up_read(&key->sem);
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key_put(key);
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return ret;
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}
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int verity_verify_sig_parse_opt_args(struct dm_arg_set *as,
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struct dm_verity *v,
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struct dm_verity_sig_opts *sig_opts,
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unsigned int *argc,
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const char *arg_name)
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{
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struct dm_target *ti = v->ti;
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int ret = 0;
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const char *sig_key = NULL;
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if (!*argc) {
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ti->error = DM_VERITY_VERIFY_ERR("Signature key not specified");
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return -EINVAL;
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}
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sig_key = dm_shift_arg(as);
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(*argc)--;
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ret = verity_verify_get_sig_from_key(sig_key, sig_opts);
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if (ret < 0)
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ti->error = DM_VERITY_VERIFY_ERR("Invalid key specified");
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v->signature_key_desc = kstrdup(sig_key, GFP_KERNEL);
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if (!v->signature_key_desc)
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return -ENOMEM;
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return ret;
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}
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/*
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* verify_verify_roothash - Verify the root hash of the verity hash device
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* using builtin trusted keys.
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*
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* @root_hash: For verity, the roothash/data to be verified.
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* @root_hash_len: Size of the roothash/data to be verified.
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* @sig_data: The trusted signature that verifies the roothash/data.
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* @sig_len: Size of the signature.
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*
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*/
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int verity_verify_root_hash(const void *root_hash, size_t root_hash_len,
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const void *sig_data, size_t sig_len)
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{
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int ret;
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if (!root_hash || root_hash_len == 0)
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return -EINVAL;
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if (!sig_data || sig_len == 0) {
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if (DM_VERITY_IS_SIG_FORCE_ENABLED())
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return -ENOKEY;
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else
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return 0;
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}
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ret = verify_pkcs7_signature(root_hash, root_hash_len, sig_data,
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sig_len,
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#ifdef CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG_SECONDARY_KEYRING
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VERIFY_USE_SECONDARY_KEYRING,
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#else
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NULL,
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#endif
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VERIFYING_UNSPECIFIED_SIGNATURE, NULL, NULL);
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#ifdef CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG_PLATFORM_KEYRING
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if (ret == -ENOKEY || ret == -EKEYREJECTED)
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ret = verify_pkcs7_signature(root_hash, root_hash_len, sig_data,
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sig_len,
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VERIFY_USE_PLATFORM_KEYRING,
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VERIFYING_UNSPECIFIED_SIGNATURE, NULL, NULL);
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#endif
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return ret;
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}
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void verity_verify_sig_opts_cleanup(struct dm_verity_sig_opts *sig_opts)
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{
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kfree(sig_opts->sig);
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sig_opts->sig = NULL;
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sig_opts->sig_size = 0;
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}
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