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Subject[PATCH 3/4] KEYS: validate key trust only with selected owner key
Date
This patch provides kernel parameter to specify owner's key id which
must be used for trust validate of keys. Keys signed with other keys
are not trusted.

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
---
crypto/asymmetric_keys/x509_public_key.c | 27 ++++++++--
include/keys/owner_keyring.h | 27 ----------
init/Kconfig | 10 ----
kernel/Makefile | 1 -
kernel/owner_keyring.c | 85 --------------------------------
5 files changed, 24 insertions(+), 126 deletions(-)
delete mode 100644 include/keys/owner_keyring.h
delete mode 100644 kernel/owner_keyring.c

diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
index 962f9b9..d46b790 100644
--- a/crypto/asymmetric_keys/x509_public_key.c
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -19,12 +19,24 @@
#include <keys/asymmetric-subtype.h>
#include <keys/asymmetric-parser.h>
#include <keys/system_keyring.h>
-#include <keys/owner_keyring.h>
#include <crypto/hash.h>
#include "asymmetric_keys.h"
#include "public_key.h"
#include "x509_parser.h"

+static char *owner_keyid;
+static int __init default_owner_keyid_set(char *str)
+{
+ if (!str) /* default system keyring */
+ return 1;
+
+ if (strncmp(str, "id:", 3) == 0)
+ owner_keyid = str; /* owner local key 'id:xxxxxx' */
+
+ return 1;
+}
+__setup("keys_ownerid=", default_owner_keyid_set);
+
/*
* Find a key in the given keyring by issuer and authority.
*/
@@ -170,6 +182,16 @@ static int x509_validate_trust(struct x509_certificate *cert,
if (!trust_keyring)
return -EOPNOTSUPP;

+ if (owner_keyid) {
+ /* validate trust only with the owner_keyid if specified */
+ /* partial match of keyid according to the asymmetric_type.c */
+ int idlen = strlen(owner_keyid) - 3; /* - id: */
+ int authlen = strlen(cert->authority);
+ char *auth = cert->authority + authlen - idlen;
+ if (idlen > authlen || strcasecmp(owner_keyid + 3, auth))
+ return -EPERM;
+ }
+
key = x509_request_asymmetric_key(trust_keyring,
cert->issuer, strlen(cert->issuer),
cert->authority,
@@ -239,8 +261,7 @@ static int x509_key_preparse(struct key_preparsed_payload *prep)
if (ret < 0)
goto error_free_cert;
} else if (!prep->trusted) {
- ret = x509_validate_trust(cert,
- get_system_or_owner_trusted_keyring());
+ ret = x509_validate_trust(cert, get_system_trusted_keyring());
if (!ret)
prep->trusted = 1;
}
diff --git a/include/keys/owner_keyring.h b/include/keys/owner_keyring.h
deleted file mode 100644
index 78dd09d..0000000
--- a/include/keys/owner_keyring.h
+++ /dev/null
@@ -1,27 +0,0 @@
-/*
- * Copyright (C) 2014 IBM Corporation
- * Author: Mimi Zohar <zohar@us.ibm.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 2 of the License.
- */
-
-#ifndef _KEYS_OWNER_KEYRING_H
-#define _KEYS_OWNER_KEYRING_H
-
-#ifdef CONFIG_OWNER_TRUSTED_KEYRING
-
-#include <linux/key.h>
-
-extern struct key *owner_trusted_keyring;
-extern struct key *get_system_or_owner_trusted_keyring(void);
-
-#else
-static inline struct key *get_system_or_owner_trusted_keyring(void)
-{
- return get_system_trusted_keyring();
-}
-
-#endif
-#endif /* _KEYS_OWNER_KEYRING_H */
diff --git a/init/Kconfig b/init/Kconfig
index 7876787..009a797 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1661,16 +1661,6 @@ config SYSTEM_TRUSTED_KEYRING

Keys in this keyring are used by module signature checking.

-config OWNER_TRUSTED_KEYRING
- bool "Verify certificate signatures using a specific system key"
- depends on SYSTEM_TRUSTED_KEYRING
- help
- Verify a certificate's signature, before adding the key to
- a trusted keyring, using a specific key on the system trusted
- keyring. The specific key on the system trusted keyring is
- identified using the kernel boot command line option
- "keys_ownerid" and is added to the owner_trusted_keyring.
-
menuconfig MODULES
bool "Enable loadable module support"
option modules
diff --git a/kernel/Makefile b/kernel/Makefile
index 7b44efd..bc010ee 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -44,7 +44,6 @@ obj-$(CONFIG_UID16) += uid16.o
obj-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += system_keyring.o system_certificates.o
obj-$(CONFIG_MODULES) += module.o
obj-$(CONFIG_MODULE_SIG) += module_signing.o
-obj-$(CONFIG_OWNER_TRUSTED_KEYRING) += owner_keyring.o
obj-$(CONFIG_KALLSYMS) += kallsyms.o
obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
obj-$(CONFIG_KEXEC) += kexec.o
diff --git a/kernel/owner_keyring.c b/kernel/owner_keyring.c
deleted file mode 100644
index a31b865..0000000
--- a/kernel/owner_keyring.c
+++ /dev/null
@@ -1,85 +0,0 @@
-/*
- * Copyright (C) 2014 IBM Corporation
- * Author: Mimi Zohar <zohar@us.ibm.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 2 of the License.
- */
-
-#include <linux/export.h>
-#include <linux/kernel.h>
-#include <linux/sched.h>
-#include <linux/cred.h>
-#include <linux/err.h>
-#include <keys/asymmetric-type.h>
-#include <keys/system_keyring.h>
-#include "module-internal.h"
-
-struct key *owner_trusted_keyring;
-static int use_owner_trusted_keyring;
-
-static char *owner_keyid;
-static int __init default_owner_keyid_set(char *str)
-{
- if (!str) /* default system keyring */
- return 1;
-
- if (strncmp(str, "id:", 3) == 0)
- owner_keyid = str; /* owner local key 'id:xxxxxx' */
-
- return 1;
-}
-
-__setup("keys_ownerid=", default_owner_keyid_set);
-
-struct key *get_system_or_owner_trusted_keyring(void)
-{
- return use_owner_trusted_keyring ? owner_trusted_keyring :
- get_system_trusted_keyring();
-}
-
-static __init int owner_trusted_keyring_init(void)
-{
- pr_notice("Initialize the owner trusted keyring\n");
-
- owner_trusted_keyring =
- keyring_alloc(".owner_keyring",
- KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
- ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
- KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH),
- KEY_ALLOC_NOT_IN_QUOTA, NULL);
- if (IS_ERR(owner_trusted_keyring))
- panic("Can't allocate owner trusted keyring\n");
-
- set_bit(KEY_FLAG_TRUSTED_ONLY, &owner_trusted_keyring->flags);
- return 0;
-}
-
-device_initcall(owner_trusted_keyring_init);
-
-void load_owner_identified_key(void)
-{
- key_ref_t key_ref;
- int ret;
-
- if (!owner_keyid)
- return;
-
- key_ref = keyring_search(make_key_ref(system_trusted_keyring, 1),
- &key_type_asymmetric, owner_keyid);
- if (IS_ERR(key_ref)) {
- pr_warn("Request for unknown %s key\n", owner_keyid);
- goto out;
- }
- ret = key_link(owner_trusted_keyring, key_ref_to_ptr(key_ref));
- pr_info("Loaded owner key %s %s\n", owner_keyid,
- ret < 0 ? "failed" : "succeeded");
- key_ref_put(key_ref);
- if (!ret)
- use_owner_trusted_keyring = 1;
-out:
- return;
-}
-
-late_initcall(load_owner_identified_key);
--
1.9.1


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