upstream commit

small refactor of cipher.c: make ciphercontext opaque to
callers feedback and ok markus@

Upstream-ID: 094849f8be68c3bdad2c0f3dee551ecf7be87f6f

1 files changed, 109 insertions, 56 deletions

diff --git a/cipher.c b/cipher.c
index 031bda9ec..747b59bf0 100644
--- a/cipher.c
+++ b/cipher.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: cipher.c,v 1.101 2015/12/10 17:08:40 mmcc Exp $ */
+/* $OpenBSD: cipher.c,v 1.102 2016/08/03 05:41:57 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -57,6 +57,15 @@ extern const EVP_CIPHER *evp_ssh1_3des(void);
 extern int ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
 #endif
 
+struct sshcipher_ctx {
+        int     plaintext;
+        int     encrypt;
+        EVP_CIPHER_CTX *evp;
+        struct chachapoly_ctx cp_ctx; /* XXX union with evp? */
+        struct aesctr_ctx ac_ctx; /* XXX union with evp? */
+        const struct sshcipher *cipher;
+};
+
 struct sshcipher {
         char    *name;
         int     number;         /* for ssh1 only */
@@ -206,6 +215,18 @@ cipher_is_cbc(const struct sshcipher *c)
 }
 
 u_int
+cipher_ctx_is_plaintext(struct sshcipher_ctx *cc)
+{
+        return cc->plaintext;
+}
+
+u_int
+cipher_ctx_get_number(struct sshcipher_ctx *cc)
+{
+        return cc->cipher->number;
+}
+
+u_int
 cipher_mask_ssh1(int client)
 {
         u_int mask = 0;
@@ -297,65 +318,81 @@ cipher_warning_message(const struct sshcipher_ctx *cc)
 }
 
 int
-cipher_init(struct sshcipher_ctx *cc, const struct sshcipher *cipher,
+cipher_init(struct sshcipher_ctx **ccp, const struct sshcipher *cipher,
     const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
     int do_encrypt)
 {
-#ifdef WITH_OPENSSL
+        struct sshcipher_ctx *cc = NULL;
         int ret = SSH_ERR_INTERNAL_ERROR;
+#ifdef WITH_OPENSSL
         const EVP_CIPHER *type;
         int klen;
         u_char *junk, *discard;
+#endif
+
+        *ccp = NULL;
+        if ((cc = calloc(sizeof(*cc), 1)) == NULL)
+                return SSH_ERR_ALLOC_FAIL;
 
         if (cipher->number == SSH_CIPHER_DES) {
                 if (keylen > 8)
                         keylen = 8;
         }
-#endif
+
         cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
         cc->encrypt = do_encrypt;
 
         if (keylen < cipher->key_len ||
-            (iv != NULL && ivlen < cipher_ivlen(cipher)))
-                return SSH_ERR_INVALID_ARGUMENT;
+            (iv != NULL && ivlen < cipher_ivlen(cipher))) {
+                ret = SSH_ERR_INVALID_ARGUMENT;
+                goto out;
+        }
 
         cc->cipher = cipher;
         if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
-                return chachapoly_init(&cc->cp_ctx, key, keylen);
+                ret = chachapoly_init(&cc->cp_ctx, key, keylen);
+                goto out;
         }
 #ifndef WITH_OPENSSL
         if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
                 aesctr_keysetup(&cc->ac_ctx, key, 8 * keylen, 8 * ivlen);
                 aesctr_ivsetup(&cc->ac_ctx, iv);
-                return 0;
+                ret = 0;
+                goto out;
         }
-        if ((cc->cipher->flags & CFLAG_NONE) != 0)
-                return 0;
-        return SSH_ERR_INVALID_ARGUMENT;
-#else
+        if ((cc->cipher->flags & CFLAG_NONE) != 0) {
+                ret = 0;
+                goto out;
+        }
+        ret = SSH_ERR_INVALID_ARGUMENT;
+        goto out;
+#else /* WITH_OPENSSL */
         type = (*cipher->evptype)();
-        EVP_CIPHER_CTX_init(&cc->evp);
-        if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
+        if ((cc->evp = EVP_CIPHER_CTX_new()) == NULL) {
+                ret = SSH_ERR_ALLOC_FAIL;
+                goto out;
+        }
+        if (EVP_CipherInit(cc->evp, type, NULL, (u_char *)iv,
             (do_encrypt == CIPHER_ENCRYPT)) == 0) {
                 ret = SSH_ERR_LIBCRYPTO_ERROR;
-                goto bad;
+                goto out;
         }
         if (cipher_authlen(cipher) &&
-            !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_IV_FIXED,
+            !EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_SET_IV_FIXED,
             -1, (u_char *)iv)) {
                 ret = SSH_ERR_LIBCRYPTO_ERROR;
-                goto bad;
+                goto out;
         }
-        klen = EVP_CIPHER_CTX_key_length(&cc->evp);
+        klen = EVP_CIPHER_CTX_key_length(cc->evp);
         if (klen > 0 && keylen != (u_int)klen) {
-                if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0) {
+                if (EVP_CIPHER_CTX_set_key_length(cc->evp, keylen) == 0) {
                         ret = SSH_ERR_LIBCRYPTO_ERROR;
-                        goto bad;
+                        goto out;
                 }
         }
-        if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0) {
+        if (EVP_CipherInit(cc->evp, NULL, (u_char *)key, NULL, -1) == 0) {
                 ret = SSH_ERR_LIBCRYPTO_ERROR;
-                goto bad;
+                goto out;
         }
 
         if (cipher->discard_len > 0) {
@@ -363,21 +400,34 @@ cipher_init(struct sshcipher_ctx *cc, const struct sshcipher *cipher,
                     (discard = malloc(cipher->discard_len)) == NULL) {
                         free(junk);
                         ret = SSH_ERR_ALLOC_FAIL;
-                        goto bad;
+                        goto out;
                 }
-                ret = EVP_Cipher(&cc->evp, discard, junk, cipher->discard_len);
+                ret = EVP_Cipher(cc->evp, discard, junk, cipher->discard_len);
                 explicit_bzero(discard, cipher->discard_len);
                 free(junk);
                 free(discard);
                 if (ret != 1) {
                         ret = SSH_ERR_LIBCRYPTO_ERROR;
- bad:
-                        EVP_CIPHER_CTX_cleanup(&cc->evp);
-                        return ret;
+                        goto out;
                 }
         }
-#endif
-        return 0;
+        ret = 0;
+#endif /* WITH_OPENSSL */
+ out:
+        if (ret == 0) {
+                /* success */
+                *ccp = cc;
+        } else {
+                if (cc != NULL) {
+#ifdef WITH_OPENSSL
+                        if (cc->evp != NULL)
+                                EVP_CIPHER_CTX_free(cc->evp);
+#endif /* WITH_OPENSSL */
+                        explicit_bzero(cc, sizeof(*cc));
+                        free(cc);
+                }
+        }
+        return ret;
 }
 
 /*
@@ -418,33 +468,33 @@ cipher_crypt(struct sshcipher_ctx *cc, u_int seqnr, u_char *dest,
                 if (authlen != cipher_authlen(cc->cipher))
                         return SSH_ERR_INVALID_ARGUMENT;
                 /* increment IV */
-                if (!EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_IV_GEN,
+                if (!EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_IV_GEN,
                     1, lastiv))
                         return SSH_ERR_LIBCRYPTO_ERROR;
                 /* set tag on decyption */
                 if (!cc->encrypt &&
-                    !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_TAG,
+                    !EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_SET_TAG,
                     authlen, (u_char *)src + aadlen + len))
                         return SSH_ERR_LIBCRYPTO_ERROR;
         }
         if (aadlen) {
                 if (authlen &&
-                    EVP_Cipher(&cc->evp, NULL, (u_char *)src, aadlen) < 0)
+                    EVP_Cipher(cc->evp, NULL, (u_char *)src, aadlen) < 0)
                         return SSH_ERR_LIBCRYPTO_ERROR;
                 memcpy(dest, src, aadlen);
         }
         if (len % cc->cipher->block_size)
                 return SSH_ERR_INVALID_ARGUMENT;
-        if (EVP_Cipher(&cc->evp, dest + aadlen, (u_char *)src + aadlen,
+        if (EVP_Cipher(cc->evp, dest + aadlen, (u_char *)src + aadlen,
             len) < 0)
                 return SSH_ERR_LIBCRYPTO_ERROR;
         if (authlen) {
                 /* compute tag (on encrypt) or verify tag (on decrypt) */
-                if (EVP_Cipher(&cc->evp, NULL, NULL, 0) < 0)
+                if (EVP_Cipher(cc->evp, NULL, NULL, 0) < 0)
                         return cc->encrypt ?
                             SSH_ERR_LIBCRYPTO_ERROR : SSH_ERR_MAC_INVALID;
                 if (cc->encrypt &&
-                    !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_GET_TAG,
+                    !EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_GET_TAG,
                     authlen, dest + aadlen + len))
                         return SSH_ERR_LIBCRYPTO_ERROR;
         }
@@ -466,20 +516,23 @@ cipher_get_length(struct sshcipher_ctx *cc, u_int *plenp, u_int seqnr,
         return 0;
 }
 
-int
-cipher_cleanup(struct sshcipher_ctx *cc)
+void
+cipher_free(struct sshcipher_ctx *cc)
 {
-        if (cc == NULL || cc->cipher == NULL)
-                return 0;
+        if (cc == NULL)
+                return;
         if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
                 explicit_bzero(&cc->cp_ctx, sizeof(cc->cp_ctx));
         else if ((cc->cipher->flags & CFLAG_AESCTR) != 0)
                 explicit_bzero(&cc->ac_ctx, sizeof(cc->ac_ctx));
 #ifdef WITH_OPENSSL
-        else if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
-                return SSH_ERR_LIBCRYPTO_ERROR;
+        if (cc->evp != NULL) {
+                EVP_CIPHER_CTX_free(cc->evp);
+                cc->evp = NULL;
+        }
 #endif
-        return 0;
+        explicit_bzero(cc, sizeof(*cc));
+        free(cc);
 }
 
 /*
@@ -487,8 +540,8 @@ cipher_cleanup(struct sshcipher_ctx *cc)
  * passphrase and using the resulting 16 bytes as the key.
  */
 int
-cipher_set_key_string(struct sshcipher_ctx *cc, const struct sshcipher *cipher,
-    const char *passphrase, int do_encrypt)
+cipher_set_key_string(struct sshcipher_ctx **ccp,
+    const struct sshcipher *cipher, const char *passphrase, int do_encrypt)
 {
         u_char digest[16];
         int r = SSH_ERR_INTERNAL_ERROR;
@@ -498,7 +551,7 @@ cipher_set_key_string(struct sshcipher_ctx *cc, const struct sshcipher *cipher,
             digest, sizeof(digest))) != 0)
                 goto out;
 
-        r = cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
+        r = cipher_init(ccp, cipher, digest, 16, NULL, 0, do_encrypt);
  out:
         explicit_bzero(digest, sizeof(digest));
         return r;
@@ -523,7 +576,7 @@ cipher_get_keyiv_len(const struct sshcipher_ctx *cc)
                 ivlen = sizeof(cc->ac_ctx.ctr);
 #ifdef WITH_OPENSSL
         else
-                ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
+                ivlen = EVP_CIPHER_CTX_iv_length(cc->evp);
 #endif /* WITH_OPENSSL */
         return (ivlen);
 }
@@ -555,7 +608,7 @@ cipher_get_keyiv(struct sshcipher_ctx *cc, u_char *iv, u_int len)
         case SSH_CIPHER_SSH2:
         case SSH_CIPHER_DES:
         case SSH_CIPHER_BLOWFISH:
-                evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
+                evplen = EVP_CIPHER_CTX_iv_length(cc->evp);
                 if (evplen == 0)
                         return 0;
                 else if (evplen < 0)
@@ -568,16 +621,16 @@ cipher_get_keyiv(struct sshcipher_ctx *cc, u_char *iv, u_int len)
                 else
 #endif
                 if (cipher_authlen(c)) {
-                        if (!EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_IV_GEN,
+                        if (!EVP_CIPHER_CTX_ctrl(cc->evp, EVP_CTRL_GCM_IV_GEN,
                            len, iv))
                                return SSH_ERR_LIBCRYPTO_ERROR;
                 } else
-                        memcpy(iv, cc->evp.iv, len);
+                        memcpy(iv, cc->evp->iv, len);
                 break;
 #endif
 #ifdef WITH_SSH1
         case SSH_CIPHER_3DES:
-                return ssh1_3des_iv(&cc->evp, 0, iv, 24);
+                return ssh1_3des_iv(cc->evp, 0, iv, 24);
 #endif
         default:
                 return SSH_ERR_INVALID_ARGUMENT;
@@ -603,21 +656,21 @@ cipher_set_keyiv(struct sshcipher_ctx *cc, const u_char *iv)
         case SSH_CIPHER_SSH2:
         case SSH_CIPHER_DES:
         case SSH_CIPHER_BLOWFISH:
-                evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
+                evplen = EVP_CIPHER_CTX_iv_length(cc->evp);
                 if (evplen <= 0)
                         return SSH_ERR_LIBCRYPTO_ERROR;
                 if (cipher_authlen(c)) {
                         /* XXX iv arg is const, but EVP_CIPHER_CTX_ctrl isn't */
-                        if (!EVP_CIPHER_CTX_ctrl(&cc->evp,
+                        if (!EVP_CIPHER_CTX_ctrl(cc->evp,
                             EVP_CTRL_GCM_SET_IV_FIXED, -1, (void *)iv))
                                 return SSH_ERR_LIBCRYPTO_ERROR;
                 } else
-                        memcpy(cc->evp.iv, iv, evplen);
+                        memcpy(cc->evp->iv, iv, evplen);
                 break;
 #endif
 #ifdef WITH_SSH1
         case SSH_CIPHER_3DES:
-                return ssh1_3des_iv(&cc->evp, 1, (u_char *)iv, 24);
+                return ssh1_3des_iv(cc->evp, 1, (u_char *)iv, 24);
 #endif
         default:
                 return SSH_ERR_INVALID_ARGUMENT;
@@ -626,8 +679,8 @@ cipher_set_keyiv(struct sshcipher_ctx *cc, const u_char *iv)
 }
 
 #ifdef WITH_OPENSSL
-#define EVP_X_STATE(evp)        (evp).cipher_data
-#define EVP_X_STATE_LEN(evp)    (evp).cipher->ctx_size
+#define EVP_X_STATE(evp)        (evp)->cipher_data
+#define EVP_X_STATE_LEN(evp)    (evp)->cipher->ctx_size
 #endif
 
 int