RT3425: constant-time evp_enc
[openssl.git] / crypto / evp / evp_enc.c
index e8456322395e55694d8a60201b87baa1cc01e0dd..c06c83c0e33086294ee8b11235601d8d8970c2b1 100644 (file)
 #ifndef OPENSSL_NO_ENGINE
 #include <openssl/engine.h>
 #endif
+#ifdef OPENSSL_FIPS
+#include <openssl/fips.h>
+#endif
+#include "../constant_time_locl.h"
 #include "evp_locl.h"
 
-const char *EVP_version="EVP" OPENSSL_VERSION_PTEXT;
+#ifdef OPENSSL_FIPS
+#define M_do_cipher(ctx, out, in, inl) FIPS_cipher(ctx, out, in, inl)
+#else
+#define M_do_cipher(ctx, out, in, inl) ctx->cipher->do_cipher(ctx, out, in, inl)
+#endif
+
+
+const char EVP_version[]="EVP" OPENSSL_VERSION_PTEXT;
 
 void EVP_CIPHER_CTX_init(EVP_CIPHER_CTX *ctx)
        {
@@ -74,6 +85,13 @@ void EVP_CIPHER_CTX_init(EVP_CIPHER_CTX *ctx)
        /* ctx->cipher=NULL; */
        }
 
+EVP_CIPHER_CTX *EVP_CIPHER_CTX_new(void)
+       {
+       EVP_CIPHER_CTX *ctx=OPENSSL_malloc(sizeof *ctx);
+       if (ctx)
+               EVP_CIPHER_CTX_init(ctx);
+       return ctx;
+       }
 
 int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher,
             const unsigned char *key, const unsigned char *iv, int enc)
@@ -108,10 +126,14 @@ int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher, ENGINE *imp
                /* Ensure a context left lying around from last time is cleared
                 * (the previous check attempted to avoid this if the same
                 * ENGINE and EVP_CIPHER could be used). */
-               EVP_CIPHER_CTX_cleanup(ctx);
-
-               /* Restore encrypt field: it is zeroed by cleanup */
-               ctx->encrypt = enc;
+               if (ctx->cipher)
+                       {
+                       unsigned long flags = ctx->flags;
+                       EVP_CIPHER_CTX_cleanup(ctx);
+                       /* Restore encrypt and flags */
+                       ctx->encrypt = enc;
+                       ctx->flags = flags;
+                       }
 #ifndef OPENSSL_NO_ENGINE
                if(impl)
                        {
@@ -148,6 +170,17 @@ int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher, ENGINE *imp
                        ctx->engine = NULL;
 #endif
 
+#ifdef OPENSSL_FIPS
+               if (FIPS_mode())
+                       {
+                       const EVP_CIPHER *fcipher;
+                       if (cipher)
+                               fcipher = evp_get_fips_cipher(cipher);
+                       if (fcipher)
+                               cipher = fcipher;
+                       return FIPS_cipherinit(ctx, cipher, key, iv, enc);
+                       }
+#endif
                ctx->cipher=cipher;
                if (ctx->cipher->ctx_size)
                        {
@@ -163,7 +196,8 @@ int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher, ENGINE *imp
                        ctx->cipher_data = NULL;
                        }
                ctx->key_len = cipher->key_len;
-               ctx->flags = 0;
+               /* Preserve wrap enable flag, zero everything else */
+               ctx->flags &= EVP_CIPHER_CTX_FLAG_WRAP_ALLOW;
                if(ctx->cipher->flags & EVP_CIPH_CTRL_INIT)
                        {
                        if(!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_INIT, 0, NULL))
@@ -180,12 +214,23 @@ int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher, ENGINE *imp
                }
 #ifndef OPENSSL_NO_ENGINE
 skip_to_init:
+#endif
+#ifdef OPENSSL_FIPS
+       if (FIPS_mode())
+               return FIPS_cipherinit(ctx, cipher, key, iv, enc);
 #endif
        /* we assume block size is a power of 2 in *cryptUpdate */
        OPENSSL_assert(ctx->cipher->block_size == 1
            || ctx->cipher->block_size == 8
            || ctx->cipher->block_size == 16);
 
+       if(!(ctx->flags & EVP_CIPHER_CTX_FLAG_WRAP_ALLOW)
+               && EVP_CIPHER_CTX_mode(ctx) == EVP_CIPH_WRAP_MODE)
+               {
+               EVPerr(EVP_F_EVP_CIPHERINIT_EX, EVP_R_WRAP_MODE_NOT_ALLOWED);
+               return 0;
+               }
+
        if(!(EVP_CIPHER_CTX_flags(ctx) & EVP_CIPH_CUSTOM_IV)) {
                switch(EVP_CIPHER_CTX_mode(ctx)) {
 
@@ -197,6 +242,7 @@ skip_to_init:
                        case EVP_CIPH_OFB_MODE:
 
                        ctx->num = 0;
+                       /* fall-through */
 
                        case EVP_CIPH_CBC_MODE:
 
@@ -206,11 +252,19 @@ skip_to_init:
                        memcpy(ctx->iv, ctx->oiv, EVP_CIPHER_CTX_iv_length(ctx));
                        break;
 
+                       case EVP_CIPH_CTR_MODE:
+                       ctx->num = 0;
+                       /* Don't reuse IV for CTR mode */
+                       if(iv)
+                               memcpy(ctx->iv, iv, EVP_CIPHER_CTX_iv_length(ctx));
+                       break;
+
                        default:
                        return 0;
                        break;
                }
        }
+               
 
        if(key || (ctx->cipher->flags & EVP_CIPH_ALWAYS_CALL_INIT)) {
                if(!ctx->cipher->init(ctx,key,iv,enc)) return 0;
@@ -272,10 +326,25 @@ int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl,
        {
        int i,j,bl;
 
-       OPENSSL_assert(inl > 0);
+       if (ctx->cipher->flags & EVP_CIPH_FLAG_CUSTOM_CIPHER)
+               {
+               i = M_do_cipher(ctx, out, in, inl);
+               if (i < 0)
+                       return 0;
+               else
+                       *outl = i;
+               return 1;
+               }
+
+       if (inl <= 0)
+               {
+               *outl = 0;
+               return inl == 0;
+               }
+
        if(ctx->buf_len == 0 && (inl&(ctx->block_mask)) == 0)
                {
-               if(ctx->cipher->do_cipher(ctx,out,in,inl))
+               if(M_do_cipher(ctx,out,in,inl))
                        {
                        *outl=inl;
                        return 1;
@@ -302,7 +371,7 @@ int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl,
                        {
                        j=bl-i;
                        memcpy(&(ctx->buf[i]),in,j);
-                       if(!ctx->cipher->do_cipher(ctx,out,ctx->buf,bl)) return 0;
+                       if(!M_do_cipher(ctx,out,ctx->buf,bl)) return 0;
                        inl-=j;
                        in+=j;
                        out+=bl;
@@ -315,7 +384,7 @@ int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl,
        inl-=i;
        if (inl > 0)
                {
-               if(!ctx->cipher->do_cipher(ctx,out,in,inl)) return 0;
+               if(!M_do_cipher(ctx,out,in,inl)) return 0;
                *outl+=inl;
                }
 
@@ -337,6 +406,16 @@ int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
        int n,ret;
        unsigned int i, b, bl;
 
+       if (ctx->cipher->flags & EVP_CIPH_FLAG_CUSTOM_CIPHER)
+               {
+               ret = M_do_cipher(ctx, out, NULL, 0);
+               if (ret < 0)
+                       return 0;
+               else 
+                       *outl = ret;
+               return 1;
+               }
+
        b=ctx->cipher->block_size;
        OPENSSL_assert(b <= sizeof ctx->buf);
        if (b == 1)
@@ -359,7 +438,7 @@ int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
        n=b-bl;
        for (i=bl; i<b; i++)
                ctx->buf[i]=n;
-       ret=ctx->cipher->do_cipher(ctx,out,ctx->buf,b);
+       ret=M_do_cipher(ctx,out,ctx->buf,b);
 
 
        if(ret)
@@ -374,12 +453,25 @@ int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl,
        int fix_len;
        unsigned int b;
 
-       if (inl == 0)
+       if (ctx->cipher->flags & EVP_CIPH_FLAG_CUSTOM_CIPHER)
                {
-               *outl=0;
+               fix_len = M_do_cipher(ctx, out, in, inl);
+               if (fix_len < 0)
+                       {
+                       *outl = 0;
+                       return 0;
+                       }
+               else
+                       *outl = fix_len;
                return 1;
                }
 
+       if (inl <= 0)
+               {
+               *outl = 0;
+               return inl == 0;
+               }
+
        if (ctx->flags & EVP_CIPH_NO_PADDING)
                return EVP_EncryptUpdate(ctx, out, outl, in, inl);
 
@@ -425,11 +517,21 @@ int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
 
 int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
        {
-       int i,n;
-       unsigned int b;
-
+       unsigned int i, b;
+        unsigned char pad, padding_good;
        *outl=0;
-       b=ctx->cipher->block_size;
+
+       if (ctx->cipher->flags & EVP_CIPH_FLAG_CUSTOM_CIPHER)
+               {
+               int ret = M_do_cipher(ctx, out, NULL, 0);
+               if (ret < 0)
+                       return 0;
+               else
+                       *outl = ret;
+               return 1;
+               }
+
+       b=(unsigned int)(ctx->cipher->block_size);
        if (ctx->flags & EVP_CIPH_NO_PADDING)
                {
                if(ctx->buf_len)
@@ -448,32 +550,48 @@ int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
                        return(0);
                        }
                OPENSSL_assert(b <= sizeof ctx->final);
-               n=ctx->final[b-1];
-               if (n > (int)b)
-                       {
-                       EVPerr(EVP_F_EVP_DECRYPTFINAL_EX,EVP_R_BAD_DECRYPT);
-                       return(0);
-                       }
-               for (i=0; i<n; i++)
+               pad=ctx->final[b-1];
+
+               padding_good = (unsigned char)(~constant_time_is_zero_8(pad));
+               padding_good &= constant_time_ge_8(b, pad);
+
+                for (i = 1; i < b; ++i)
                        {
-                       if (ctx->final[--b] != n)
-                               {
-                               EVPerr(EVP_F_EVP_DECRYPTFINAL_EX,EVP_R_BAD_DECRYPT);
-                               return(0);
-                               }
+                       unsigned char is_pad_index = constant_time_lt_8(i, pad);
+                       unsigned char pad_byte_good = constant_time_eq_8(ctx->final[b-i-1], pad);
+                       padding_good &= constant_time_select_8(is_pad_index, pad_byte_good, 0xff);
                        }
-               n=ctx->cipher->block_size-n;
-               for (i=0; i<n; i++)
-                       out[i]=ctx->final[i];
-               *outl=n;
+
+               /*
+                * At least 1 byte is always padding, so we always write b - 1
+                * bytes to avoid a timing leak. The caller is required to have |b|
+                * bytes space in |out| by the API contract.
+                */
+               for (i = 0; i < b - 1; ++i)
+                       out[i] = ctx->final[i] & padding_good;
+               /* Safe cast: for a good padding, EVP_MAX_IV_LENGTH >= b >= pad */
+               *outl = padding_good & ((unsigned char)(b - pad));
+               return padding_good & 1;
                }
        else
-               *outl=0;
-       return(1);
+               {
+               *outl = 0;
+               return 1;
+               }
+       }
+
+void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx)
+       {
+       if (ctx)
+               {
+               EVP_CIPHER_CTX_cleanup(ctx);
+               OPENSSL_free(ctx);
+               }
        }
 
 int EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX *c)
        {
+#ifndef OPENSSL_FIPS
        if (c->cipher != NULL)
                {
                if(c->cipher->cleanup && !c->cipher->cleanup(c))
@@ -484,11 +602,15 @@ int EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX *c)
                }
        if (c->cipher_data)
                OPENSSL_free(c->cipher_data);
+#endif
 #ifndef OPENSSL_NO_ENGINE
        if (c->engine)
                /* The EVP_CIPHER we used belongs to an ENGINE, release the
                 * functional reference we held for this reason. */
                ENGINE_finish(c->engine);
+#endif
+#ifdef OPENSSL_FIPS
+       FIPS_cipher_ctx_cleanup(c);
 #endif
        memset(c,0,sizeof(EVP_CIPHER_CTX));
        return 1;
@@ -545,3 +667,37 @@ int EVP_CIPHER_CTX_rand_key(EVP_CIPHER_CTX *ctx, unsigned char *key)
        return 1;
        }
 
+int EVP_CIPHER_CTX_copy(EVP_CIPHER_CTX *out, const EVP_CIPHER_CTX *in)
+       {
+       if ((in == NULL) || (in->cipher == NULL))
+               {
+               EVPerr(EVP_F_EVP_CIPHER_CTX_COPY,EVP_R_INPUT_NOT_INITIALIZED);
+               return 0;
+               }
+#ifndef OPENSSL_NO_ENGINE
+       /* Make sure it's safe to copy a cipher context using an ENGINE */
+       if (in->engine && !ENGINE_init(in->engine))
+               {
+               EVPerr(EVP_F_EVP_CIPHER_CTX_COPY,ERR_R_ENGINE_LIB);
+               return 0;
+               }
+#endif
+
+       EVP_CIPHER_CTX_cleanup(out);
+       memcpy(out,in,sizeof *out);
+
+       if (in->cipher_data && in->cipher->ctx_size)
+               {
+               out->cipher_data=OPENSSL_malloc(in->cipher->ctx_size);
+               if (!out->cipher_data)
+                       {
+                       EVPerr(EVP_F_EVP_CIPHER_CTX_COPY,ERR_R_MALLOC_FAILURE);
+                       return 0;
+                       }
+               memcpy(out->cipher_data,in->cipher_data,in->cipher->ctx_size);
+               }
+
+       if (in->cipher->flags & EVP_CIPH_CUSTOM_COPY)
+               return in->cipher->ctrl((EVP_CIPHER_CTX *)in, EVP_CTRL_COPY, 0, out);
+       return 1;
+       }