From 32c4741cb66703a3c282f41d77deff4afd93342a Mon Sep 17 00:00:00 2001 From: Dmitry Kasatkin Date: Tue, 17 Jun 2014 11:56:59 +0300 Subject: [PATCH] KEYS: validate certificate trust only with builtin keys 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. Simplified Mimi's "KEYS: define an owner trusted keyring" patch Changelog v7: - rename builtin_keys to use_builtin_keys Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar --- 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, 9 insertions(+), 4 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index bdb193afe176..90c12c591168 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -569,7 +569,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. ca_keys= [KEYS] This parameter identifies a specific key(s) on the system trusted keyring to be used for certificate trust validation. - format: id: + format: { id: | builtin } ccw_timeout_log [S390] See Documentation/s390/CommonIO for details. diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c index d376195e1d08..927ce755ff67 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 use_builtin_keys; static char *ca_keyid; #ifndef MODULE @@ -34,6 +35,8 @@ static int __init ca_keys_setup(char *str) if (strncmp(str, "id:", 3) == 0) ca_keyid = str; /* owner key 'id:xxxxxx' */ + else if (strcmp(str, "builtin") == 0) + use_builtin_keys = true; return 1; } @@ -180,7 +183,6 @@ EXPORT_SYMBOL_GPL(x509_check_signature); static int x509_validate_trust(struct x509_certificate *cert, struct key *trust_keyring) { - const struct public_key *pk; struct key *key; int ret = 1; @@ -195,8 +197,9 @@ 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 (!use_builtin_keys + || test_bit(KEY_FLAG_BUILTIN, &key->flags)) + ret = x509_check_signature(key->payload.data, cert); key_put(key); } return ret; diff --git a/include/linux/key.h b/include/linux/key.h index 017b0826642f..65316f7ae794 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 52ebc70263f4..875f64e8935b 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);