* [PATCH 2/3] KEYS: Separate the kernel signature checking keyring from module signing
2013-01-17 18:03 [PATCH 1/3] KEYS: Load *.x509 files into kernel keyring David Howells
@ 2013-01-17 18:04 ` David Howells
2013-01-17 18:57 ` Mimi Zohar
2013-01-17 18:04 ` [PATCH 3/3] KEYS: Add a 'trusted' flag and a 'trusted only' flag David Howells
2013-01-17 18:44 ` [PATCH 1/3] KEYS: Load *.x509 files into kernel keyring Mimi Zohar
2 siblings, 1 reply; 9+ messages in thread
From: David Howells @ 2013-01-17 18:04 UTC (permalink / raw)
To: dmitry.kasatkin, zohar
Cc: linux-kernel, keyrings, linux-security-module, linux-crypto
Separate the kernel signature checking keyring from module signing so that it
can be used by code other than the module-signing code.
Signed-off-by: David Howells <dhowells@redhat.com>
---
init/Kconfig | 13 +++++
kernel/Makefile | 17 ++++---
kernel/modsign_certificate.S | 18 -------
kernel/modsign_pubkey.c | 104 ------------------------------------------
kernel/module-internal.h | 2 -
kernel/module_signing.c | 3 +
kernel/system_certificates.S | 18 +++++++
kernel/system_keyring.c | 101 +++++++++++++++++++++++++++++++++++++++++
8 files changed, 145 insertions(+), 131 deletions(-)
delete mode 100644 kernel/modsign_certificate.S
delete mode 100644 kernel/modsign_pubkey.c
create mode 100644 kernel/system_certificates.S
create mode 100644 kernel/system_keyring.c
diff --git a/init/Kconfig b/init/Kconfig
index 7d30240..a5363d2 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1568,6 +1568,18 @@ config BASE_SMALL
default 0 if BASE_FULL
default 1 if !BASE_FULL
+config SYSTEM_TRUSTED_KEYRING
+ bool "Provide system-wide ring of trusted keys"
+ select KEYS
+ help
+ Provide a system keyring to which trusted keys can be added. Keys in
+ the keyring are considered to be trusted. Keys may be added at will
+ by the kernel from compiled-in data and from hardware key stores, but
+ userspace may only add extra keys if those keys can be verified by
+ keys already in the keyring.
+
+ Keys in this keyring are used by module signature checking.
+
menuconfig MODULES
bool "Enable loadable module support"
help
@@ -1640,6 +1652,7 @@ config MODULE_SRCVERSION_ALL
config MODULE_SIG
bool "Module signature verification"
depends on MODULES
+ select SYSTEM_TRUSTED_KEYS
select KEYS
select CRYPTO
select ASYMMETRIC_KEY_TYPE
diff --git a/kernel/Makefile b/kernel/Makefile
index 9fe74ff..658e250 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -53,8 +53,9 @@ obj-$(CONFIG_SMP) += spinlock.o
obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o
obj-$(CONFIG_PROVE_LOCKING) += spinlock.o
obj-$(CONFIG_UID16) += uid16.o
+obj-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += system_keyring.o system_certificates.o
obj-$(CONFIG_MODULES) += module.o
-obj-$(CONFIG_MODULE_SIG) += module_signing.o modsign_pubkey.o modsign_certificate.o
+obj-$(CONFIG_MODULE_SIG) += module_signing.o
obj-$(CONFIG_KALLSYMS) += kallsyms.o
obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
obj-$(CONFIG_KEXEC) += kexec.o
@@ -133,13 +134,14 @@ targets += timeconst.h
$(obj)/timeconst.h: $(src)/timeconst.pl FORCE
$(call if_changed,timeconst)
-ifeq ($(CONFIG_MODULE_SIG),y)
###############################################################################
#
-# Roll all the X.509 certificates that we can find together and pull
-# them into the kernel.
+# Roll all the X.509 certificates that we can find together and pull them into
+# the kernel so that they get loaded into the system trusted keyring during
+# boot.
#
###############################################################################
+ifeq ($(CONFIG_SYSTEM_TRUSTED_KEYRING),y)
X509_CERTIFICATES := $(sort signing_key.x509 $(wildcard *.x509) $(wildcard $(srctree)/*.x509))
ifeq ($(X509_CERTIFICATES),)
@@ -153,10 +155,11 @@ $(shell rm $(obj)/.x509.list)
endif
endif
-kernel/modsign_certificate.o: $(obj)/x509_certificate_list
+kernel/system_certificates.o: $(obj)/x509_certificate_list
quiet_cmd_x509certs = CERTS $@
- cmd_x509certs = cat $(X509_CERTIFICATES) /dev/null >$@
+ cmd_x509certs = cat $(X509_CERTIFICATES) /dev/null >$@ $(foreach X509,$(X509_CERTIFICATES),; echo " - Including cert $(X509)")
+
targets += $(obj)/x509_certificate_list
$(obj)/x509_certificate_list: $(X509_CERTIFICATES) $(obj)/.x509.list
$(call if_changed,x509certs)
@@ -166,7 +169,9 @@ $(obj)/.x509.list:
@echo $(X509_CERTIFICATES) >$@
clean-files := x509_certificate_list .x509.list
+endif
+ifeq ($(CONFIG_MODULE_SIG),y)
###############################################################################
#
# If module signing is requested, say by allyesconfig, but a key has not been
diff --git a/kernel/modsign_certificate.S b/kernel/modsign_certificate.S
deleted file mode 100644
index 0a60203..0000000
--- a/kernel/modsign_certificate.S
+++ /dev/null
@@ -1,18 +0,0 @@
-/* SYMBOL_PREFIX defined on commandline from CONFIG_SYMBOL_PREFIX */
-#ifndef SYMBOL_PREFIX
-#define ASM_SYMBOL(sym) sym
-#else
-#define PASTE2(x,y) x##y
-#define PASTE(x,y) PASTE2(x,y)
-#define ASM_SYMBOL(sym) PASTE(SYMBOL_PREFIX, sym)
-#endif
-
-#define GLOBAL(name) \
- .globl ASM_SYMBOL(name); \
- ASM_SYMBOL(name):
-
- .section ".init.data","aw"
-
-GLOBAL(modsign_certificate_list)
- .incbin "kernel/x509_certificate_list"
-GLOBAL(modsign_certificate_list_end)
diff --git a/kernel/modsign_pubkey.c b/kernel/modsign_pubkey.c
deleted file mode 100644
index 2b6e699..0000000
--- a/kernel/modsign_pubkey.c
+++ /dev/null
@@ -1,104 +0,0 @@
-/* Public keys for module signature verification
- *
- * Copyright (C) 2012 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.
- */
-
-#include <linux/kernel.h>
-#include <linux/sched.h>
-#include <linux/cred.h>
-#include <linux/err.h>
-#include <keys/asymmetric-type.h>
-#include "module-internal.h"
-
-struct key *modsign_keyring;
-
-extern __initdata const u8 modsign_certificate_list[];
-extern __initdata const u8 modsign_certificate_list_end[];
-
-/*
- * We need to make sure ccache doesn't cache the .o file as it doesn't notice
- * if modsign.pub changes.
- */
-static __initdata const char annoy_ccache[] = __TIME__ "foo";
-
-/*
- * Load the compiled-in keys
- */
-static __init int module_verify_init(void)
-{
- pr_notice("Initialise module verification\n");
-
- modsign_keyring = keyring_alloc(".module_sign",
- KUIDT_INIT(0), KGIDT_INIT(0),
- current_cred(),
- ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
- KEY_USR_VIEW | KEY_USR_READ),
- KEY_ALLOC_NOT_IN_QUOTA, NULL);
- if (IS_ERR(modsign_keyring))
- panic("Can't allocate module signing keyring\n");
-
- return 0;
-}
-
-/*
- * Must be initialised before we try and load the keys into the keyring.
- */
-device_initcall(module_verify_init);
-
-/*
- * Load the compiled-in keys
- */
-static __init int load_module_signing_keys(void)
-{
- key_ref_t key;
- const u8 *p, *end;
- size_t plen;
-
- pr_notice("Loading module verification certificates\n");
-
- end = modsign_certificate_list_end;
- p = modsign_certificate_list;
- while (p < end) {
- /* Each cert begins with an ASN.1 SEQUENCE tag and must be more
- * than 256 bytes in size.
- */
- if (end - p < 4)
- goto dodgy_cert;
- if (p[0] != 0x30 &&
- p[1] != 0x82)
- goto dodgy_cert;
- plen = (p[2] << 8) | p[3];
- plen += 4;
- if (plen > end - p)
- goto dodgy_cert;
-
- key = key_create_or_update(make_key_ref(modsign_keyring, 1),
- "asymmetric",
- NULL,
- p,
- plen,
- (KEY_POS_ALL & ~KEY_POS_SETATTR) |
- KEY_USR_VIEW,
- KEY_ALLOC_NOT_IN_QUOTA);
- if (IS_ERR(key))
- pr_err("MODSIGN: Problem loading in-kernel X.509 certificate (%ld)\n",
- PTR_ERR(key));
- else
- pr_notice("MODSIGN: Loaded cert '%s'\n",
- key_ref_to_ptr(key)->description);
- p += plen;
- }
-
- return 0;
-
-dodgy_cert:
- pr_err("MODSIGN: Problem parsing in-kernel X.509 certificate list\n");
- return 0;
-}
-late_initcall(load_module_signing_keys);
diff --git a/kernel/module-internal.h b/kernel/module-internal.h
index 24f9247..915e123 100644
--- a/kernel/module-internal.h
+++ b/kernel/module-internal.h
@@ -9,6 +9,4 @@
* 2 of the Licence, or (at your option) any later version.
*/
-extern struct key *modsign_keyring;
-
extern int mod_verify_sig(const void *mod, unsigned long *_modlen);
diff --git a/kernel/module_signing.c b/kernel/module_signing.c
index f2970bd..0034e36 100644
--- a/kernel/module_signing.c
+++ b/kernel/module_signing.c
@@ -14,6 +14,7 @@
#include <crypto/public_key.h>
#include <crypto/hash.h>
#include <keys/asymmetric-type.h>
+#include <keys/system_keyring.h>
#include "module-internal.h"
/*
@@ -157,7 +158,7 @@ static struct key *request_asymmetric_key(const char *signer, size_t signer_len,
pr_debug("Look up: \"%s\"\n", id);
- key = keyring_search(make_key_ref(modsign_keyring, 1),
+ key = keyring_search(make_key_ref(system_trusted_keyring, 1),
&key_type_asymmetric, id);
if (IS_ERR(key))
pr_warn("Request for unknown module key '%s' err %ld\n",
diff --git a/kernel/system_certificates.S b/kernel/system_certificates.S
new file mode 100644
index 0000000..86240df
--- /dev/null
+++ b/kernel/system_certificates.S
@@ -0,0 +1,18 @@
+/* SYMBOL_PREFIX defined on commandline from CONFIG_SYMBOL_PREFIX */
+#ifndef SYMBOL_PREFIX
+#define ASM_SYMBOL(sym) sym
+#else
+#define PASTE2(x,y) x##y
+#define PASTE(x,y) PASTE2(x,y)
+#define ASM_SYMBOL(sym) PASTE(SYMBOL_PREFIX, sym)
+#endif
+
+#define GLOBAL(name) \
+ .globl ASM_SYMBOL(name); \
+ ASM_SYMBOL(name):
+
+ .section ".init.data","aw"
+
+GLOBAL(system_certificate_list)
+ .incbin "kernel/x509_certificate_list"
+GLOBAL(system_certificate_list_end)
diff --git a/kernel/system_keyring.c b/kernel/system_keyring.c
new file mode 100644
index 0000000..a3ca76f
--- /dev/null
+++ b/kernel/system_keyring.c
@@ -0,0 +1,101 @@
+/* System trusted keyring for trusted public keys
+ *
+ * Copyright (C) 2012 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.
+ */
+
+#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 *system_trusted_keyring;
+EXPORT_SYMBOL_GPL(system_trusted_keyring);
+
+extern __initdata const u8 system_certificate_list[];
+extern __initdata const u8 system_certificate_list_end[];
+
+/*
+ * Load the compiled-in keys
+ */
+static __init int system_trusted_keyring_init(void)
+{
+ pr_notice("Initialise system trusted keyring\n");
+
+ system_trusted_keyring =
+ keyring_alloc(".system_keyring",
+ KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
+ ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
+ KEY_USR_VIEW | KEY_USR_READ),
+ KEY_ALLOC_NOT_IN_QUOTA, NULL);
+ if (IS_ERR(system_trusted_keyring))
+ panic("Can't allocate system trusted keyring\n");
+
+ return 0;
+}
+
+/*
+ * Must be initialised before we try and load the keys into the keyring.
+ */
+device_initcall(system_trusted_keyring_init);
+
+/*
+ * Load the compiled-in list of X.509 certificates.
+ */
+static __init int load_system_certificate_list(void)
+{
+ key_ref_t key;
+ const u8 *p, *end;
+ size_t plen;
+
+ pr_notice("Loading compiled-in X.509 certificates\n");
+
+ end = system_certificate_list_end;
+ p = system_certificate_list;
+ while (p < end) {
+ /* Each cert begins with an ASN.1 SEQUENCE tag and must be more
+ * than 256 bytes in size.
+ */
+ if (end - p < 4)
+ goto dodgy_cert;
+ if (p[0] != 0x30 &&
+ p[1] != 0x82)
+ goto dodgy_cert;
+ plen = (p[2] << 8) | p[3];
+ plen += 4;
+ if (plen > end - p)
+ goto dodgy_cert;
+
+ key = key_create_or_update(make_key_ref(system_trusted_keyring, 1),
+ "asymmetric",
+ NULL,
+ p,
+ plen,
+ (KEY_POS_ALL & ~KEY_POS_SETATTR) |
+ KEY_USR_VIEW,
+ KEY_ALLOC_NOT_IN_QUOTA);
+ if (IS_ERR(key))
+ pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
+ PTR_ERR(key));
+ else
+ pr_notice("Loaded X.509 cert '%s'\n",
+ key_ref_to_ptr(key)->description);
+ p += plen;
+ }
+
+ return 0;
+
+dodgy_cert:
+ pr_err("Problem parsing in-kernel X.509 certificate list\n");
+ return 0;
+}
+late_initcall(load_system_certificate_list);
^ permalink raw reply related [flat|nested] 9+ messages in thread* [PATCH 3/3] KEYS: Add a 'trusted' flag and a 'trusted only' flag
2013-01-17 18:03 [PATCH 1/3] KEYS: Load *.x509 files into kernel keyring David Howells
2013-01-17 18:04 ` [PATCH 2/3] KEYS: Separate the kernel signature checking keyring from module signing David Howells
@ 2013-01-17 18:04 ` David Howells
2013-01-30 8:29 ` Kasatkin, Dmitry
2013-01-17 18:44 ` [PATCH 1/3] KEYS: Load *.x509 files into kernel keyring Mimi Zohar
2 siblings, 1 reply; 9+ messages in thread
From: David Howells @ 2013-01-17 18:04 UTC (permalink / raw)
To: dmitry.kasatkin, zohar
Cc: linux-kernel, keyrings, linux-security-module, linux-crypto
Add KEY_FLAG_TRUSTED to indicate that a key either comes from a trusted source
or had a cryptographic signature chain that led back to a trusted key the
kernel already possessed.
Add KEY_FLAGS_TRUSTED_ONLY to indicate that a keyring will only accept links to
keys marked with KEY_FLAGS_TRUSTED.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
include/linux/key-type.h | 1 +
include/linux/key.h | 3 +++
kernel/system_keyring.c | 4 +++-
security/keys/key.c | 8 ++++++++
security/keys/keyring.c | 4 ++++
5 files changed, 19 insertions(+), 1 deletion(-)
diff --git a/include/linux/key-type.h b/include/linux/key-type.h
index 518a53a..f942b2d 100644
--- a/include/linux/key-type.h
+++ b/include/linux/key-type.h
@@ -45,6 +45,7 @@ struct key_preparsed_payload {
const void *data; /* Raw data */
size_t datalen; /* Raw datalen */
size_t quotalen; /* Quota length for proposed payload */
+ bool trusted; /* True if key is trusted */
};
typedef int (*request_key_actor_t)(struct key_construction *key,
diff --git a/include/linux/key.h b/include/linux/key.h
index 4dfde11..0b32a09 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -162,6 +162,8 @@ struct key {
#define KEY_FLAG_NEGATIVE 5 /* set if key is negative */
#define KEY_FLAG_ROOT_CAN_CLEAR 6 /* set if key can be cleared by root without permission */
#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 */
/* the description string
* - this is used to match a key against search criteria
@@ -203,6 +205,7 @@ extern struct key *key_alloc(struct key_type *type,
#define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */
#define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */
#define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */
+#define KEY_ALLOC_TRUSTED 0x0004 /* Key should be flagged as trusted */
extern void key_revoke(struct key *key);
extern void key_invalidate(struct key *key);
diff --git a/kernel/system_keyring.c b/kernel/system_keyring.c
index a3ca76f..dae8778 100644
--- a/kernel/system_keyring.c
+++ b/kernel/system_keyring.c
@@ -40,6 +40,7 @@ static __init int system_trusted_keyring_init(void)
if (IS_ERR(system_trusted_keyring))
panic("Can't allocate system trusted keyring\n");
+ set_bit(KEY_FLAG_TRUSTED_ONLY, &system_trusted_keyring->flags);
return 0;
}
@@ -82,7 +83,8 @@ static __init int load_system_certificate_list(void)
plen,
(KEY_POS_ALL & ~KEY_POS_SETATTR) |
KEY_USR_VIEW,
- KEY_ALLOC_NOT_IN_QUOTA);
+ KEY_ALLOC_NOT_IN_QUOTA |
+ KEY_ALLOC_TRUSTED);
if (IS_ERR(key))
pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
PTR_ERR(key));
diff --git a/security/keys/key.c b/security/keys/key.c
index 8fb7c7b..f3de9e4 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -299,6 +299,8 @@ struct key *key_alloc(struct key_type *type, const char *desc,
if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
key->flags |= 1 << KEY_FLAG_IN_QUOTA;
+ if (flags & KEY_ALLOC_TRUSTED)
+ key->flags |= 1 << KEY_FLAG_TRUSTED;
memset(&key->type_data, 0, sizeof(key->type_data));
@@ -813,6 +815,7 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref,
prep.data = payload;
prep.datalen = plen;
prep.quotalen = ktype->def_datalen;
+ prep.trusted = flags & KEY_ALLOC_TRUSTED;
if (ktype->preparse) {
ret = ktype->preparse(&prep);
if (ret < 0) {
@@ -826,6 +829,11 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref,
goto error_free_prep;
}
+ key_ref = ERR_PTR(-EPERM);
+ if (!prep.trusted && test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags))
+ goto error_free_prep;
+ flags |= prep.trusted ? KEY_ALLOC_TRUSTED : 0;
+
ret = __key_link_begin(keyring, ktype, description, &prealloc);
if (ret < 0) {
key_ref = ERR_PTR(ret);
diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index 6ece7f2..f18d7ff 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -1006,6 +1006,10 @@ int key_link(struct key *keyring, struct key *key)
key_check(keyring);
key_check(key);
+ if (test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags) &&
+ !test_bit(KEY_FLAG_TRUSTED, &key->flags))
+ return -EPERM;
+
ret = __key_link_begin(keyring, key->type, key->description, &prealloc);
if (ret == 0) {
ret = __key_link_check_live_key(keyring, key);
^ permalink raw reply related [flat|nested] 9+ messages in thread