Re: [PATCH 4/9] KEYS: Allow unrestricted boot-time addition of keys to secondary keyring

Petko Manolov
2016-11-17T07:06:18Z

On 16-11-16 18:11:13, David Howells wrote:
> Allow keys to be added to the system secondary certificates keyring during
> kernel initialisation in an unrestricted fashion. Such keys are implicitly
> trusted and don't have their trust chains checked on link.

Well, I for one do not explicitly trust these keys. I may even want to
completely remove or replace them.

> This allows keys in the UEFI database to be added in secure boot mode for the
> purposes of module signing.

The key import should not be automatic, it should be optional. Same applies to
the validation process.

Petko

> Signed-off-by: David Howells <dhowells@redhat.com>
> ---
>
> certs/internal.h | 18 ++++++++++++++++++
> certs/system_keyring.c | 33 +++++++++++++++++++++++++++++++++
> 2 files changed, 51 insertions(+)
> create mode 100644 certs/internal.h
>
> diff --git a/certs/internal.h b/certs/internal.h
> new file mode 100644
> index 000000000000..5dcbefb0c23a
> --- /dev/null
> +++ b/certs/internal.h
> @@ -0,0 +1,18 @@
> +/* Internal definitions
> + *
> + * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
> + * Written by David Howells (dhowells@redhat.com)
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public Licence
> + * as published by the Free Software Foundation; either version
> + * 2 of the Licence, or (at your option) any later version.
> + */
> +
> +/*
> + * system_keyring.c
> + */
> +#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
> +extern void __init add_trusted_secondary_key(const char *source,
> + const void *data, size_t len);
> +#endif
> diff --git a/certs/system_keyring.c b/certs/system_keyring.c
> index 50979d6dcecd..dfddcf6e6c88 100644
> --- a/certs/system_keyring.c
> +++ b/certs/system_keyring.c
> @@ -17,6 +17,7 @@
> #include <keys/asymmetric-type.h>
> #include <keys/system_keyring.h>
> #include <crypto/pkcs7.h>
> +#include "internal.h"
>
> static struct key *builtin_trusted_keys;
> #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
> @@ -242,3 +243,35 @@ int verify_pkcs7_signature(const void *data, size_t len,
> EXPORT_SYMBOL_GPL(verify_pkcs7_signature);
>
> #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */
> +
> +#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
> +/**
> + * add_trusted_secondary_key - Add to secondary keyring with no validation
> + * @source: Source of key
> + * @data: The blob holding the key
> + * @len: The length of the data blob
> + *
> + * Add a key to the secondary keyring without checking its trust chain. This
> + * is available only during kernel initialisation.
> + */
> +void __init add_trusted_secondary_key(const char *source,
> + const void *data, size_t len)
> +{
> + key_ref_t key;
> +
> + key = key_create_or_update(make_key_ref(secondary_trusted_keys, 1),
> + "asymmetric",
> + NULL, data, len,
> + (KEY_POS_ALL & ~KEY_POS_SETATTR) |
> + KEY_USR_VIEW,
> + KEY_ALLOC_NOT_IN_QUOTA |
> + KEY_ALLOC_BYPASS_RESTRICTION);
> +
> + if (IS_ERR(key))
> + pr_err("Problem loading %s X.509 certificate (%ld)\n",
> + source, PTR_ERR(key));
> + else
> + pr_notice("Loaded %s cert '%s' linked to secondary sys keyring\n",
> + source, key_ref_to_ptr(key)->description);
> +}
> +#endif /* CONFIG_SECONDARY_TRUSTED_KEYRING */
>
> --
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