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authorThiago Jung Bauermann <bauerman@linux.ibm.com>2019-06-28 05:19:26 +0300
committerMimi Zohar <zohar@linux.ibm.com>2019-08-06 01:40:19 +0300
commite201af16d1ec76ccd19b90484d767984ff451f18 (patch)
treef2e532988d868a67e3ca59c96e93a5a3e50f013f /crypto/asymmetric_keys
parent2a7bf671186eb5d1a47ef192aefbdf788f5b38fe (diff)
downloadlinux-e201af16d1ec76ccd19b90484d767984ff451f18.tar.xz
PKCS#7: Introduce pkcs7_get_digest()
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>
Diffstat (limited to 'crypto/asymmetric_keys')
-rw-r--r--crypto/asymmetric_keys/pkcs7_verify.c33
1 files changed, 33 insertions, 0 deletions
diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys/pkcs7_verify.c
index 11bee67fa9cc..ce49820caa97 100644
--- 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_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;
@@ -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