Avoid PKCS #1 v1.5 signature attack discovered by Daniel Bleichenbacher

[oweals/openssl.git] / crypto / rsa / rsa_eay.c

diff --git a/crypto/rsa/rsa_eay.c b/crypto/rsa/rsa_eay.c
index 56da944845996ee6655028a2e7715a68599504a1..d6e07a2c5c1c8448bc61b83bba2ada3c1de3f89c 100644 (file)
--- a/crypto/rsa/rsa_eay.c
+++ b/crypto/rsa/rsa_eay.c
@@ -56,7 +56,7 @@
  * [including the GNU Public Licence.]
  */
 /* ====================================================================
- * Copyright (c) 1998-2005 The OpenSSL Project.  All rights reserved.
+ * Copyright (c) 1998-2006 The OpenSSL Project.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -238,40 +238,63 @@ err:
        return(r);
        }
 
-static BN_BLINDING *rsa_get_blinding(RSA *rsa, BIGNUM **r, int *local, BN_CTX *ctx)
+static BN_BLINDING *rsa_get_blinding(RSA *rsa, int *local, BN_CTX *ctx)
 {
        BN_BLINDING *ret;
+       int got_write_lock = 0;
+
+       CRYPTO_r_lock(CRYPTO_LOCK_RSA);
 
        if (rsa->blinding == NULL)
                {
+               CRYPTO_r_unlock(CRYPTO_LOCK_RSA);
+               CRYPTO_w_lock(CRYPTO_LOCK_RSA);
+               got_write_lock = 1;
+
                if (rsa->blinding == NULL)
-                       {
-                       CRYPTO_w_lock(CRYPTO_LOCK_RSA);
-                       if (rsa->blinding == NULL)
-                               rsa->blinding = RSA_setup_blinding(rsa, ctx);
-                       CRYPTO_w_unlock(CRYPTO_LOCK_RSA);
-                       }
+                       rsa->blinding = RSA_setup_blinding(rsa, ctx);
                }
 
        ret = rsa->blinding;
        if (ret == NULL)
-               return NULL;
+               goto err;
 
-       if (BN_BLINDING_get_thread_id(ret) != CRYPTO_thread_id())
+       if (BN_BLINDING_get_thread_id(ret) == CRYPTO_thread_id())
+               {
+               /* rsa->blinding is ours! */
+
+               *local = 1;
+               }
+       else
                {
-               *local = 0;
+               /* resort to rsa->mt_blinding instead */
+
+               *local = 0; /* instructs rsa_blinding_convert(), rsa_blinding_invert()
+                            * that the BN_BLINDING is shared, meaning that accesses
+                            * require locks, and that the blinding factor must be
+                            * stored outside the BN_BLINDING
+                            */
+
                if (rsa->mt_blinding == NULL)
                        {
-                       CRYPTO_w_lock(CRYPTO_LOCK_RSA);
+                       if (!got_write_lock)
+                               {
+                               CRYPTO_r_unlock(CRYPTO_LOCK_RSA);
+                               CRYPTO_w_lock(CRYPTO_LOCK_RSA);
+                               got_write_lock = 1;
+                               }
+                       
                        if (rsa->mt_blinding == NULL)
                                rsa->mt_blinding = RSA_setup_blinding(rsa, ctx);
-                       CRYPTO_w_unlock(CRYPTO_LOCK_RSA);
                        }
                ret = rsa->mt_blinding;
                }
-       else
-               *local = 1;
 
+ err:
+       if (got_write_lock)
+               CRYPTO_w_unlock(CRYPTO_LOCK_RSA);
+       else
+               CRYPTO_r_unlock(CRYPTO_LOCK_RSA);
        return ret;
 }
 
@@ -358,7 +381,7 @@ static int RSA_eay_private_encrypt(int flen, const unsigned char *from,
 
        if (!(rsa->flags & RSA_FLAG_NO_BLINDING))
                {
-               blinding = rsa_get_blinding(rsa, &br, &local_blinding, ctx);
+               blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
                if (blinding == NULL)
                        {
                        RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT, ERR_R_INTERNAL_ERROR);
@@ -479,7 +502,7 @@ static int RSA_eay_private_decrypt(int flen, const unsigned char *from,
 
        if (!(rsa->flags & RSA_FLAG_NO_BLINDING))
                {
-               blinding = rsa_get_blinding(rsa, &br, &local_blinding, ctx);
+               blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
                if (blinding == NULL)
                        {
                        RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT, ERR_R_INTERNAL_ERROR);
@@ -617,6 +640,15 @@ static int RSA_eay_public_decrypt(int flen, const unsigned char *from,
                {
        case RSA_PKCS1_PADDING:
                r=RSA_padding_check_PKCS1_type_1(to,num,buf,i,num);
+               /* Generally signatures should be at least 2/3 padding, though
+                  this isn't possible for really short keys and some standard
+                  signature schemes, so don't check if the unpadded data is
+                  small. */
+               if(r > 42 && 3*8*r >= BN_num_bits(rsa->n))
+                       {
+                       RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, RSA_R_PKCS1_PADDING_TOO_SHORT);
+                       goto err;
+                       }
                break;
        case RSA_X931_PADDING:
                r=RSA_padding_check_X931(to,num,buf,i,num);