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SubjectRe: [PATCH v1a 2/2] KEYS: validate certificate trust only with builtin keys
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On Thu, 2014-06-12 at 23:17 +0300, Dmitry Kasatkin wrote:
> Instead of allowing public keys, with certificates signed by any
> key on the system trusted keyring, to be added to a trusted keyring,
> this patch further restricts the certificates to those signed only by
> builtin keys on the system keyring.
>
> This patch defines a new option 'builtin' for the kernel parameter
> 'keys_ownerid' to allow trust validation using builtin keys.

Thanks, this patch works without a separate 'owned' trusted keyring, but
we need to wait until the UEFI key patches are upstreamed.

thanks,

Mimi

> Idea belongs to Mimi Zohar.
>
> Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
> ---
> Documentation/kernel-parameters.txt | 2 +-
> crypto/asymmetric_keys/x509_public_key.c | 9 +++++++--
> include/linux/key.h | 1 +
> kernel/system_keyring.c | 1 +
> 4 files changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index 7a810d3..336dabe 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -1437,7 +1437,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
> keys_ownerid=[KEYS] This parameter identifies a specific key(s) on
> the system trusted keyring to be used for certificate
> trust validation.
> - format: id:<keyid>
> + format: { id:<keyid> | builtin }
>
> kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
> Format: <Controller#>[,poll interval]
> diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
> index d46b790..c3805a8 100644
> --- a/crypto/asymmetric_keys/x509_public_key.c
> +++ b/crypto/asymmetric_keys/x509_public_key.c
> @@ -24,6 +24,7 @@
> #include "public_key.h"
> #include "x509_parser.h"
>
> +static bool builtin_keys;
> static char *owner_keyid;
> static int __init default_owner_keyid_set(char *str)
> {
> @@ -32,6 +33,8 @@ static int __init default_owner_keyid_set(char *str)
>
> if (strncmp(str, "id:", 3) == 0)
> owner_keyid = str; /* owner local key 'id:xxxxxx' */
> + else if (strcmp(str, "builtin") == 0)
> + builtin_keys = true;
>
> return 1;
> }
> @@ -197,8 +200,10 @@ static int x509_validate_trust(struct x509_certificate *cert,
> cert->authority,
> strlen(cert->authority));
> if (!IS_ERR(key)) {
> - pk = key->payload.data;
> - ret = x509_check_signature(pk, cert);
> + if (!builtin_keys || test_bit(KEY_FLAG_BUILTIN, &key->flags)) {
> + pk = key->payload.data;
> + ret = x509_check_signature(pk, cert);
> + }
> key_put(key);
> }
> return ret;
> diff --git a/include/linux/key.h b/include/linux/key.h
> index cd0abb8..67c8e7e 100644
> --- a/include/linux/key.h
> +++ b/include/linux/key.h
> @@ -170,6 +170,7 @@ struct key {
> #define KEY_FLAG_INVALIDATED 7 /* set if key has been invalidated */
> #define KEY_FLAG_TRUSTED 8 /* set if key is trusted */
> #define KEY_FLAG_TRUSTED_ONLY 9 /* set if keyring only accepts links to trusted keys */
> +#define KEY_FLAG_BUILTIN 10 /* set if key is builtin */
>
> /* the key type and key description string
> * - the desc is used to match a key against search criteria
> diff --git a/kernel/system_keyring.c b/kernel/system_keyring.c
> index 52ebc70..875f64e 100644
> --- a/kernel/system_keyring.c
> +++ b/kernel/system_keyring.c
> @@ -89,6 +89,7 @@ static __init int load_system_certificate_list(void)
> pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
> PTR_ERR(key));
> } else {
> + set_bit(KEY_FLAG_BUILTIN, &key_ref_to_ptr(key)->flags);
> pr_notice("Loaded X.509 cert '%s'\n",
> key_ref_to_ptr(key)->description);
> key_ref_put(key);








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