From: "Lee, Chun-Yi" <joeyli.kernel@gmail.com>
To: David Howells <dhowells@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
"David S . Miller" <davem@davemloft.net>,
keyrings@vger.kernel.org, linux-crypto@vger.kernel.org,
linux-kernel@vger.kernel.org, "Lee, Chun-Yi" <jlee@suse.com>
Subject: [RFC PATCH 2/2] PKCS#7: Check codeSigning EKU for kernel module and kexec pe verification
Date: Tue, 20 Oct 2020 14:50:01 +0800 [thread overview]
Message-ID: <20201020065001.13836-3-jlee@suse.com> (raw)
In-Reply-To: <20201020065001.13836-1-jlee@suse.com>
This patch adds the logic for checking the CodeSigning extended
key usage extenstion when verifying signature of kernel module or
kexec PE binary in PKCS#7.
Signed-off-by: "Lee, Chun-Yi" <jlee@suse.com>
---
certs/system_keyring.c | 2 +-
crypto/asymmetric_keys/Kconfig | 10 ++++++++++
crypto/asymmetric_keys/pkcs7_trust.c | 37 +++++++++++++++++++++++++++++++++---
include/crypto/pkcs7.h | 3 ++-
4 files changed, 47 insertions(+), 5 deletions(-)
diff --git a/certs/system_keyring.c b/certs/system_keyring.c
index 798291177186..4104f5465d8a 100644
--- a/certs/system_keyring.c
+++ b/certs/system_keyring.c
@@ -242,7 +242,7 @@ int verify_pkcs7_message_sig(const void *data, size_t len,
goto error;
}
}
- ret = pkcs7_validate_trust(pkcs7, trusted_keys);
+ ret = pkcs7_validate_trust(pkcs7, trusted_keys, usage);
if (ret < 0) {
if (ret == -ENOKEY)
pr_devel("PKCS#7 signature not signed with a trusted key\n");
diff --git a/crypto/asymmetric_keys/Kconfig b/crypto/asymmetric_keys/Kconfig
index 1f1f004dc757..6e3de0c3b5f0 100644
--- a/crypto/asymmetric_keys/Kconfig
+++ b/crypto/asymmetric_keys/Kconfig
@@ -96,4 +96,14 @@ config SIGNED_PE_FILE_VERIFICATION
This option provides support for verifying the signature(s) on a
signed PE binary.
+config CHECK_CODESIGN_EKU
+ bool "Check codeSigning extended key usage"
+ depends on PKCS7_MESSAGE_PARSER=y
+ depends on SYSTEM_DATA_VERIFICATION
+ help
+ This option provides support for checking the codeSigning extended
+ key usage extension when verifying the signature in PKCS#7. It
+ affects kernel module verification and kexec PE binary verification
+ now.
+
endif # ASYMMETRIC_KEY_TYPE
diff --git a/crypto/asymmetric_keys/pkcs7_trust.c b/crypto/asymmetric_keys/pkcs7_trust.c
index 61af3c4d82cc..1d2318ff63db 100644
--- a/crypto/asymmetric_keys/pkcs7_trust.c
+++ b/crypto/asymmetric_keys/pkcs7_trust.c
@@ -16,12 +16,36 @@
#include <crypto/public_key.h>
#include "pkcs7_parser.h"
+#ifdef CONFIG_CHECK_CODESIGN_EKU
+static bool check_codesign_eku(struct key *key,
+ enum key_being_used_for usage)
+{
+ struct public_key *public_key = key->payload.data[asym_crypto];
+
+ switch (usage) {
+ case VERIFYING_MODULE_SIGNATURE:
+ case VERIFYING_KEXEC_PE_SIGNATURE:
+ return !!(public_key->eku & EKU_codeSigning);
+ default:
+ break;
+ }
+ return true;
+}
+#else
+static bool check_codesign_eku(struct key *key,
+ enum key_being_used_for usage)
+{
+ return true;
+}
+#endif
+
/**
* Check the trust on one PKCS#7 SignedInfo block.
*/
static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7,
struct pkcs7_signed_info *sinfo,
- struct key *trust_keyring)
+ struct key *trust_keyring,
+ enum key_being_used_for usage)
{
struct public_key_signature *sig = sinfo->sig;
struct x509_certificate *x509, *last = NULL, *p;
@@ -112,6 +136,12 @@ static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7,
return -ENOKEY;
matched:
+ if (!check_codesign_eku(key, usage)) {
+ pr_warn("sinfo %u: The signer %x key is not CodeSigning\n",
+ sinfo->index, key_serial(key));
+ key_put(key);
+ return -ENOKEY;
+ }
ret = verify_signature(key, sig);
key_put(key);
if (ret < 0) {
@@ -156,7 +186,8 @@ static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7,
* May also return -ENOMEM.
*/
int pkcs7_validate_trust(struct pkcs7_message *pkcs7,
- struct key *trust_keyring)
+ struct key *trust_keyring,
+ enum key_being_used_for usage)
{
struct pkcs7_signed_info *sinfo;
struct x509_certificate *p;
@@ -167,7 +198,7 @@ int pkcs7_validate_trust(struct pkcs7_message *pkcs7,
p->seen = false;
for (sinfo = pkcs7->signed_infos; sinfo; sinfo = sinfo->next) {
- ret = pkcs7_validate_trust_one(pkcs7, sinfo, trust_keyring);
+ ret = pkcs7_validate_trust_one(pkcs7, sinfo, trust_keyring, usage);
switch (ret) {
case -ENOKEY:
continue;
diff --git a/include/crypto/pkcs7.h b/include/crypto/pkcs7.h
index 38ec7f5f9041..b3b48240ba73 100644
--- a/include/crypto/pkcs7.h
+++ b/include/crypto/pkcs7.h
@@ -30,7 +30,8 @@ extern int pkcs7_get_content_data(const struct pkcs7_message *pkcs7,
* pkcs7_trust.c
*/
extern int pkcs7_validate_trust(struct pkcs7_message *pkcs7,
- struct key *trust_keyring);
+ struct key *trust_keyring,
+ enum key_being_used_for usage);
/*
* pkcs7_verify.c
--
2.16.4
next prev parent reply other threads:[~2020-10-20 6:50 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-20 6:49 [RFC PATCH 0/2] Check codeSigning extended key usage extension Lee, Chun-Yi
2020-10-20 6:50 ` [RFC PATCH 1/2] X.509: Add CodeSigning extended key usage parsing Lee, Chun-Yi
2020-10-20 6:50 ` Lee, Chun-Yi [this message]
2020-10-20 13:42 ` [RFC PATCH 2/2] PKCS#7: Check codeSigning EKU for kernel module and kexec pe verification Ben Boeckel
2020-10-20 14:56 ` Randy Dunlap
2020-10-21 10:20 ` joeyli
2020-10-21 10:10 ` joeyli
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201020065001.13836-3-jlee@suse.com \
--to=joeyli.kernel@gmail.com \
--cc=davem@davemloft.net \
--cc=dhowells@redhat.com \
--cc=herbert@gondor.apana.org.au \
--cc=jlee@suse.com \
--cc=keyrings@vger.kernel.org \
--cc=linux-crypto@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).