deprecate EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal()

This switches EVP_CipherFinal() to work as EVP_EncryptFinal() and
EVP_DecryptFinal() do, always clearing the cipher context on completion.
Indicate that, since it is not possible to tell whether this function will
clear the context (the API has changed over time in OpenSSL), it is better to
use the _ex() variants and explicitly clear instead.

ok beck@

2 files changed, 23 insertions, 7 deletions

diff --git a/src/lib/libcrypto/doc/EVP_EncryptInit.pod b/src/lib/libcrypto/doc/EVP_EncryptInit.pod
index 02d02ba5f5..e72c101c94 100644
--- a/src/lib/libcrypto/doc/EVP_EncryptInit.pod
+++ b/src/lib/libcrypto/doc/EVP_EncryptInit.pod
@@ -23,7 +23,7 @@ EVP_des_ede3_cfb, EVP_desx_cbc, EVP_rc4, EVP_rc4_40, EVP_idea_cbc,
 EVP_idea_ecb, EVP_idea_cfb, EVP_idea_ofb, EVP_idea_cbc, EVP_rc2_cbc,
 EVP_rc2_ecb, EVP_rc2_cfb, EVP_rc2_ofb, EVP_rc2_40_cbc, EVP_rc2_64_cbc,
 EVP_bf_cbc, EVP_bf_ecb, EVP_bf_cfb, EVP_bf_ofb, EVP_cast5_cbc,
-EVP_cast5_ecb, EVP_cast5_cfb, EVP_cast5_ofb, 
+EVP_cast5_ecb, EVP_cast5_cfb, EVP_cast5_ofb,
 EVP_aes_128_gcm, EVP_aes_192_gcm, EVP_aes_256_gcm, EVP_aes_128_ccm,
 EVP_aes_192_ccm, EVP_aes_256_ccm, EVP_rc5_32_12_16_cbc,
 EVP_rc5_32_12_16_cfb, EVP_rc5_32_12_16_ecb, EVP_rc5_32_12_16_ofb
@@ -168,9 +168,13 @@ initialized and they always use the default cipher implementation.
 
 EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal() are
 identical to EVP_EncryptFinal_ex(), EVP_DecryptFinal_ex() and
-EVP_CipherFinal_ex(). In previous releases they also used to clean up
-the B<ctx>, but this is no longer done and EVP_CIPHER_CTX_clean()
-must be called to free any context resources.
+EVP_CipherFinal_ex(). In previous releases of OpenSSL they also used to clean
+up the B<ctx>, but this is no longer done and EVP_CIPHER_CTX_clean()
+must be called to free any context resources. As of LibreSSL 2.4,
+EVP_EncryptFinal() and EVP_DecryptFinal() will always clean up, and
+EVP_CipherFinal() also cleans up as of LibreSSL 2.5. The use of
+EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal() is not
+recommended.
 
 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
 return an EVP_CIPHER structure when passed a cipher name, a NID or an
diff --git a/src/lib/libcrypto/evp/evp_enc.c b/src/lib/libcrypto/evp/evp_enc.c
index f8d2cb78d4..c89f69c9a2 100644
--- a/src/lib/libcrypto/evp/evp_enc.c
+++ b/src/lib/libcrypto/evp/evp_enc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: evp_enc.c,v 1.31 2016/05/30 13:42:54 beck Exp $ */
+/* $OpenBSD: evp_enc.c,v 1.32 2016/09/03 14:54:25 bcook Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -260,13 +260,19 @@ EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
                 return EVP_DecryptFinal_ex(ctx, out, outl);
 }
 
+__warn_references(EVP_CipherFinal,
+    "warning: EVP_CipherFinal is often misused, please use EVP_CipherFinal_ex and EVP_CIPHER_CTX_cleanup");
+
 int
 EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
 {
+        int ret;
         if (ctx->encrypt)
-                return EVP_EncryptFinal_ex(ctx, out, outl);
+                ret = EVP_EncryptFinal_ex(ctx, out, outl);
         else
-                return EVP_DecryptFinal_ex(ctx, out, outl);
+                ret = EVP_DecryptFinal_ex(ctx, out, outl);
+        (void) EVP_CIPHER_CTX_cleanup(ctx);
+        return ret;
 }
 
 int
@@ -365,6 +371,9 @@ EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl,
         return 1;
 }
 
+__warn_references(EVP_EncryptFinal,
+    "warning: EVP_EncryptFinal is often misused, please use EVP_EncryptFinal_ex and EVP_CIPHER_CTX_cleanup");
+
 int
 EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
 {
@@ -479,6 +488,9 @@ EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl,
         return 1;
 }
 
+__warn_references(EVP_DecryptFinal,
+    "warning: EVP_DecryptFinal is often misused, please use EVP_DecryptFinal_ex and EVP_CIPHER_CTX_cleanup");
+
 int
 EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
 {