From: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Date: Thu, 27 Jun 2019 23:19:26 -0300
Subject: PKCS#7: Introduce pkcs7_get_digest()
Patch-mainline: v5.4-rc1
Git-commit: e201af16d1ec76ccd19b90484d767984ff451f18
References: jsc#SLE-9870
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.ibm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Acked-by: Lee, Chun-Yi <jlee@suse.com>
---
crypto/asymmetric_keys/pkcs7_verify.c | 33 +++++++++++++++++++++++++++++++++
include/crypto/pkcs7.h | 4 ++++
2 files changed, 37 insertions(+)
--- a/crypto/asymmetric_keys/pkcs7_verify.c
+++ b/crypto/asymmetric_keys/pkcs7_verify.c
@@ -12,6 +12,7 @@
#include <linux/err.h>
#include <linux/asn1.h>
#include <crypto/hash.h>
+#include <crypto/hash_info.h>
#include <crypto/public_key.h>
#include "pkcs7_parser.h"
@@ -29,6 +30,10 @@ static int pkcs7_digest(struct pkcs7_mes
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;
@@ -117,6 +122,34 @@ error_no_desc:
return ret;
}
+int pkcs7_get_digest(struct pkcs7_message *pkcs7, const u8 **buf, u32 *len,
+ enum hash_algo *hash_algo)
+{
+ struct pkcs7_signed_info *sinfo = pkcs7->signed_infos;
+ int i, 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;
+
+ for (i = 0; i < HASH_ALGO__LAST; i++)
+ if (!strcmp(hash_algo_name[i], sinfo->sig->hash_algo)) {
+ *hash_algo = i;
+ break;
+ }
+
+ 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
--- a/include/crypto/pkcs7.h
+++ b/include/crypto/pkcs7.h
@@ -9,6 +9,7 @@
#define _CRYPTO_PKCS7_H
#include <linux/verification.h>
+#include <linux/hash_info.h>
#include <crypto/public_key.h>
struct key;
@@ -40,4 +41,7 @@ extern int pkcs7_verify(struct pkcs7_mes
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,
+ u32 *len, enum hash_algo *hash_algo);
+
#endif /* _CRYPTO_PKCS7_H */