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From: Thiago Jung Bauermann <bauerman@linux.ibm.com>
To: linux-integrity@vger.kernel.org
Cc: linux-security-module@vger.kernel.org, keyrings@vger.kernel.org,
	linux-crypto@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-kernel@vger.kernel.org,
	Mimi Zohar <zohar@linux.vnet.ibm.com>,
	Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
	James Morris <jmorris@namei.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	David Howells <dhowells@redhat.com>,
	David Woodhouse <dwmw2@infradead.org>,
	Jessica Yu <jeyu@kernel.org>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>,
	"AKASHI, Takahiro" <takahiro.akashi@linaro.org>,
	Thiago Jung Bauermann <bauerman@linux.ibm.com>
Subject: [PATCH v7 03/14] PKCS#7: Introduce pkcs7_get_digest()
Date: Tue, 22 May 2018 21:12:42 -0300	[thread overview]
Message-ID: <20180523001253.15247-4-bauerman@linux.ibm.com> (raw)
In-Reply-To: <20180523001253.15247-1-bauerman@linux.ibm.com>

IMA will need to access the digest of the PKCS7 message (as calculated by
the kernel) before the signature is verified, so introduce
pkcs7_get_digest() for that purpose.

Also, modify pkcs7_digest() to detect when the digest was already
calculated so that it doesn't have to do redundant work. Verifying that
sinfo->sig->digest isn't NULL is sufficient because both places which
allocate sinfo->sig (pkcs7_parse_message() and pkcs7_note_signed_info())
use kzalloc() so sig->digest is always initialized to zero.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Reviewed-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
---
 crypto/asymmetric_keys/pkcs7_verify.c | 25 +++++++++++++++++++++++++
 include/crypto/pkcs7.h                |  3 +++
 2 files changed, 28 insertions(+)

diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys/pkcs7_verify.c
index 97c77f66b20d..e61f121bfc87 100644
--- a/crypto/asymmetric_keys/pkcs7_verify.c
+++ b/crypto/asymmetric_keys/pkcs7_verify.c
@@ -33,6 +33,10 @@ static int pkcs7_digest(struct pkcs7_message *pkcs7,
 
 	kenter(",%u,%s", sinfo->index, sinfo->sig->hash_algo);
 
+	/* The digest was calculated already. */
+	if (sig->digest)
+		return 0;
+
 	if (!sinfo->sig->hash_algo)
 		return -ENOPKG;
 
@@ -122,6 +126,27 @@ static int pkcs7_digest(struct pkcs7_message *pkcs7,
 	return ret;
 }
 
+int pkcs7_get_digest(struct pkcs7_message *pkcs7, const u8 **buf, u8 *len)
+{
+	struct pkcs7_signed_info *sinfo = pkcs7->signed_infos;
+	int ret;
+
+	/*
+	 * This function doesn't support messages with more than one signature.
+	 */
+	if (sinfo == NULL || sinfo->next != NULL)
+		return -EBADMSG;
+
+	ret = pkcs7_digest(pkcs7, sinfo);
+	if (ret)
+		return ret;
+
+	*buf = sinfo->sig->digest;
+	*len = sinfo->sig->digest_size;
+
+	return 0;
+}
+
 /*
  * Find the key (X.509 certificate) to use to verify a PKCS#7 message.  PKCS#7
  * uses the issuer's name and the issuing certificate serial number for
diff --git a/include/crypto/pkcs7.h b/include/crypto/pkcs7.h
index 6f51d0cb6d12..cfaea9c37f4a 100644
--- a/include/crypto/pkcs7.h
+++ b/include/crypto/pkcs7.h
@@ -46,4 +46,7 @@ extern int pkcs7_verify(struct pkcs7_message *pkcs7,
 extern int pkcs7_supply_detached_data(struct pkcs7_message *pkcs7,
 				      const void *data, size_t datalen);
 
+extern int pkcs7_get_digest(struct pkcs7_message *pkcs7, const u8 **buf,
+			    u8 *len);
+
 #endif /* _CRYPTO_PKCS7_H */

  parent reply	other threads:[~2018-05-23  0:26 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-23  0:12 [PATCH v7 00/14] Appended signatures support for IMA appraisal Thiago Jung Bauermann
2018-05-23  0:12 ` [PATCH v7 01/14] MODSIGN: Export module signature definitions Thiago Jung Bauermann
2018-05-23  0:12 ` [PATCH v7 02/14] PKCS#7: Refactor verify_pkcs7_signature() and add pkcs7_get_message_sig() Thiago Jung Bauermann
2018-05-23  0:12 ` Thiago Jung Bauermann [this message]
2018-05-23  0:12 ` [PATCH v7 04/14] integrity: Introduce struct evm_xattr Thiago Jung Bauermann
2018-05-23  0:12 ` [PATCH v7 05/14] integrity: Introduce integrity_keyring_from_id() Thiago Jung Bauermann
2018-05-23  0:12 ` [PATCH v7 06/14] integrity: Introduce asymmetric_sig_has_known_key() Thiago Jung Bauermann
2018-05-23  0:12 ` [PATCH v7 07/14] integrity: Select CONFIG_KEYS instead of depending on it Thiago Jung Bauermann
2018-05-23  0:12 ` [PATCH v7 08/14] ima: Introduce is_signed() Thiago Jung Bauermann
2018-05-23  0:12 ` [PATCH v7 09/14] ima: Export func_tokens Thiago Jung Bauermann
2018-05-23  0:12 ` [PATCH v7 10/14] ima: Add modsig appraise_type option for module-style appended signatures Thiago Jung Bauermann
2018-05-23  0:12 ` [PATCH v7 11/14] ima: Implement support " Thiago Jung Bauermann
2018-05-23  0:12 ` [PATCH v7 12/14] ima: Add new "d-sig" template field Thiago Jung Bauermann
2018-05-23  0:12 ` [PATCH v7 13/14] ima: Write modsig to the measurement list Thiago Jung Bauermann
2018-05-23  0:12 ` [PATCH v7 14/14] ima: Store the measurement again when appraising a modsig Thiago Jung Bauermann

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