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MODSIGN: Extract the blob PKCS#7 signature verifier from module signing 

Extract the function that drives the PKCS#7 signature verification given a
data blob and a PKCS#7 blob out from the module signing code and lump it with
the system keyring code as it's generic.  This makes it independent of module
config options and opens it to use by the firmware loader.

Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ming Lei <ming.lei@canonical.com>
Cc: Seth Forshee <seth.forshee@canonical.com>
Cc: Kyle McMartin <kyle@kernel.org>
This commit is contained in:
David Howells 2015-07-20 21:16:28 +01:00
parent 1c39449921
commit 091f6e26eb
4 changed files with 75 additions and 53 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
include/keys/system_keyring.h
View File

@ -28,4 +28,9 @@ static inline struct key *get_system_trusted_keyring(void)
}
#endif
#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
extern int system_verify_data(const void *data, unsigned long len,
const void *raw_pkcs7, size_t pkcs7_len);
#endif
#endif /* _KEYS_SYSTEM_KEYRING_H */

29
init/Kconfig
View File

@ -1752,6 +1752,24 @@ config SYSTEM_TRUSTED_KEYRING
Keys in this keyring are used by module signature checking.
config SYSTEM_DATA_VERIFICATION
def_bool n
select SYSTEM_TRUSTED_KEYRING
select KEYS
select CRYPTO
select ASYMMETRIC_KEY_TYPE
select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
select PUBLIC_KEY_ALGO_RSA
select ASN1
select OID_REGISTRY
select X509_CERTIFICATE_PARSER
select PKCS7_MESSAGE_PARSER
help
Provide PKCS#7 message verification using the contents of the system
trusted keyring to provide public keys. This then can be used for
module verification, kexec image verification and firmware blob
verification.
config PROFILING
bool "Profiling support"
help
@ -1860,16 +1878,7 @@ config MODULE_SRCVERSION_ALL
config MODULE_SIG
bool "Module signature verification"
depends on MODULES
select SYSTEM_TRUSTED_KEYRING
select KEYS
select CRYPTO
select ASYMMETRIC_KEY_TYPE
select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
select PUBLIC_KEY_ALGO_RSA
select ASN1
select OID_REGISTRY
select X509_CERTIFICATE_PARSER
select PKCS7_MESSAGE_PARSER
select SYSTEM_DATA_VERIFICATION
help
Check modules for valid signatures upon load: the signature
is simply appended to the module. For more information see

44
kernel/module_signing.c
View File

@ -10,10 +10,8 @@
*/
#include <linux/kernel.h>
#include <linux/err.h>
#include <keys/system_keyring.h>
#include <crypto/public_key.h>
#include <crypto/pkcs7.h>
#include "module-internal.h"
/*
@ -36,46 +34,6 @@ struct module_signature {
__be32 sig_len; /* Length of signature data */
};
/*
* Verify a PKCS#7-based signature on a module.
*/
static int mod_verify_pkcs7(const void *mod, unsigned long modlen,
const void *raw_pkcs7, size_t pkcs7_len)
{
struct pkcs7_message *pkcs7;
bool trusted;
int ret;
pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len);
if (IS_ERR(pkcs7))
return PTR_ERR(pkcs7);
/* The data should be detached - so we need to supply it. */
if (pkcs7_supply_detached_data(pkcs7, mod, modlen) < 0) {
pr_err("PKCS#7 signature with non-detached data\n");
ret = -EBADMSG;
goto error;
}
ret = pkcs7_verify(pkcs7);
if (ret < 0)
goto error;
ret = pkcs7_validate_trust(pkcs7, system_trusted_keyring, &trusted);
if (ret < 0)
goto error;
if (!trusted) {
pr_err("PKCS#7 signature not signed with a trusted key\n");
ret = -ENOKEY;
}
error:
pkcs7_free_message(pkcs7);
pr_devel("<==%s() = %d\n", __func__, ret);
return ret;
}
/*
* Verify the signature on a module.
*/
@ -114,5 +72,5 @@ int mod_verify_sig(const void *mod, unsigned long *_modlen)
return -EBADMSG;
}
return mod_verify_pkcs7(mod, modlen, mod + modlen, sig_len);
return system_verify_data(mod, modlen, mod + modlen, sig_len);
}

50
kernel/system_keyring.c
View File

@ -16,6 +16,7 @@
#include <linux/err.h>
#include <keys/asymmetric-type.h>
#include <keys/system_keyring.h>
#include <crypto/pkcs7.h>
struct key *system_trusted_keyring;
EXPORT_SYMBOL_GPL(system_trusted_keyring);
@ -103,3 +104,52 @@ dodgy_cert:
return 0;
}
late_initcall(load_system_certificate_list);
#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
/**
* Verify a PKCS#7-based signature on system data.
* @data: The data to be verified.
* @len: Size of @data.
* @raw_pkcs7: The PKCS#7 message that is the signature.
* @pkcs7_len: The size of @raw_pkcs7.
*/
int system_verify_data(const void *data, unsigned long len,
const void *raw_pkcs7, size_t pkcs7_len)
{
struct pkcs7_message *pkcs7;
bool trusted;
int ret;
pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len);
if (IS_ERR(pkcs7))
return PTR_ERR(pkcs7);
/* The data should be detached - so we need to supply it. */
if (pkcs7_supply_detached_data(pkcs7, data, len) < 0) {
pr_err("PKCS#7 signature with non-detached data\n");
ret = -EBADMSG;
goto error;
}
ret = pkcs7_verify(pkcs7);
if (ret < 0)
goto error;
ret = pkcs7_validate_trust(pkcs7, system_trusted_keyring, &trusted);
if (ret < 0)
goto error;
if (!trusted) {
pr_err("PKCS#7 signature not signed with a trusted key\n");
ret = -ENOKEY;
}
error:
pkcs7_free_message(pkcs7);
pr_devel("<==%s() = %d\n", __func__, ret);
return ret;
}
EXPORT_SYMBOL_GPL(system_verify_data);
#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */