From c886bef63a4820d12fbc956f62747840fba8a88e Mon Sep 17 00:00:00 2001
From: Greg Hudson <ghudson@mit.edu>
Date: Sat, 3 Feb 2018 20:53:42 -0500
Subject: [PATCH] Add vector support to k5_sha256()

Add a length argument so that multiple krb5_data values can be passed
to k5_sha256(), for efficient computation of SHA-256 hashes over
concatenations of data values.

(cherry picked from commit 4f3373e8c55b3e9bdfb5b065e07214c5816c85fa)
---
 src/include/k5-int.h                 | 4 ++--
 src/lib/crypto/builtin/sha2/sha256.c | 6 ++++--
 src/lib/crypto/crypto_tests/t_sha2.c | 2 +-
 src/lib/crypto/openssl/sha256.c      | 6 ++++--
 src/lib/krb5/rcache/rc_conv.c        | 2 +-
 5 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/src/include/k5-int.h b/src/include/k5-int.h
index 10b034037..7c549bce2 100644
--- a/src/include/k5-int.h
+++ b/src/include/k5-int.h
@@ -634,9 +634,9 @@ krb5int_arcfour_gsscrypt(const krb5_keyblock *keyblock, krb5_keyusage usage,
 
 #define K5_SHA256_HASHLEN (256 / 8)
 
-/* Write the SHA-256 hash of in to out. */
+/* Write the SHA-256 hash of in (containing n elements) to out. */
 krb5_error_code
-k5_sha256(const krb5_data *in, uint8_t out[K5_SHA256_HASHLEN]);
+k5_sha256(const krb5_data *in, size_t n, uint8_t out[K5_SHA256_HASHLEN]);
 
 /*
  * Attempt to zero memory in a way that compilers won't optimize out.
diff --git a/src/lib/crypto/builtin/sha2/sha256.c b/src/lib/crypto/builtin/sha2/sha256.c
index e34bed575..4b5fe10a3 100644
--- a/src/lib/crypto/builtin/sha2/sha256.c
+++ b/src/lib/crypto/builtin/sha2/sha256.c
@@ -257,12 +257,14 @@ k5_sha256_final(void *res, SHA256_CTX *m)
 }
 
 krb5_error_code
-k5_sha256(const krb5_data *in, uint8_t out[K5_SHA256_HASHLEN])
+k5_sha256(const krb5_data *in, size_t n, uint8_t out[K5_SHA256_HASHLEN])
 {
     SHA256_CTX ctx;
+    size_t i;
 
     k5_sha256_init(&ctx);
-    k5_sha256_update(&ctx, in->data, in->length);
+    for (i = 0; i < n; i++)
+        k5_sha256_update(&ctx, in[i].data, in[i].length);
     k5_sha256_final(out, &ctx);
     return 0;
 }
diff --git a/src/lib/crypto/crypto_tests/t_sha2.c b/src/lib/crypto/crypto_tests/t_sha2.c
index 12f32869b..e6fa58498 100644
--- a/src/lib/crypto/crypto_tests/t_sha2.c
+++ b/src/lib/crypto/crypto_tests/t_sha2.c
@@ -125,7 +125,7 @@ hash_test(const struct krb5_hash_provider *hash, struct test *tests)
 
 	    if (hash == &krb5int_hash_sha256) {
 		/* Try again using k5_sha256(). */
-		if (k5_sha256(&iov.data, (uint8_t *)hval.data) != 0)
+		if (k5_sha256(&iov.data, 1, (uint8_t *)hval.data) != 0)
 		    abort();
 		if (memcmp(hval.data, t->hash, hval.length) != 0)
 		    abort();
diff --git a/src/lib/crypto/openssl/sha256.c b/src/lib/crypto/openssl/sha256.c
index fa095d472..0edd8b7ba 100644
--- a/src/lib/crypto/openssl/sha256.c
+++ b/src/lib/crypto/openssl/sha256.c
@@ -34,16 +34,18 @@
 #include <openssl/evp.h>
 
 krb5_error_code
-k5_sha256(const krb5_data *in, uint8_t out[K5_SHA256_HASHLEN])
+k5_sha256(const krb5_data *in, size_t n, uint8_t out[K5_SHA256_HASHLEN])
 {
     EVP_MD_CTX *ctx;
+    size_t i;
     int ok;
 
     ctx = EVP_MD_CTX_new();
     if (ctx == NULL)
         return ENOMEM;
     ok = EVP_DigestInit_ex(ctx, EVP_sha256(), NULL);
-    ok = ok && EVP_DigestUpdate(ctx, in->data, in->length);
+    for (i = 0; i < n; i++)
+        ok = ok && EVP_DigestUpdate(ctx, in[i].data, in[i].length);
     ok = ok && EVP_DigestFinal_ex(ctx, out, NULL);
     EVP_MD_CTX_free(ctx);
     return ok ? 0 : ENOMEM;
diff --git a/src/lib/krb5/rcache/rc_conv.c b/src/lib/krb5/rcache/rc_conv.c
index 0e021f5d8..f2fe528ac 100644
--- a/src/lib/krb5/rcache/rc_conv.c
+++ b/src/lib/krb5/rcache/rc_conv.c
@@ -58,7 +58,7 @@ krb5_rc_hash_message(krb5_context context, const krb5_data *message,
     *out = NULL;
 
     /* Calculate the binary checksum. */
-    retval = k5_sha256(message, cksum);
+    retval = k5_sha256(message, 1, cksum);
     if (retval)
         return retval;