1 files changed, 51 insertions, 29 deletions

diff --git a/src/lib/libcrypto/rsa/rsa_eay.c b/src/lib/libcrypto/rsa/rsa_eay.c
index 7c941885f0..2e1ddd48d3 100644
--- a/src/lib/libcrypto/rsa/rsa_eay.c
+++ b/src/lib/libcrypto/rsa/rsa_eay.c
@@ -314,51 +314,56 @@ static BN_BLINDING *rsa_get_blinding(RSA *rsa, int *local, BN_CTX *ctx)
         return ret;
 }
 
-static int rsa_blinding_convert(BN_BLINDING *b, int local, BIGNUM *f,
-        BIGNUM *r, BN_CTX *ctx)
-{
-        if (local)
+static int rsa_blinding_convert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
+        BN_CTX *ctx)
+        {
+        if (unblind == NULL)
+                /* Local blinding: store the unblinding factor
+                 * in BN_BLINDING. */
                 return BN_BLINDING_convert_ex(f, NULL, b, ctx);
         else
                 {
-                int ret;
-                CRYPTO_r_lock(CRYPTO_LOCK_RSA_BLINDING);
-                ret = BN_BLINDING_convert_ex(f, r, b, ctx);
-                CRYPTO_r_unlock(CRYPTO_LOCK_RSA_BLINDING);
-                return ret;
-                }
-}
-
-static int rsa_blinding_invert(BN_BLINDING *b, int local, BIGNUM *f,
-        BIGNUM *r, BN_CTX *ctx)
-{
-        if (local)
-                return BN_BLINDING_invert_ex(f, NULL, b, ctx);
-        else
-                {
+                /* Shared blinding: store the unblinding factor
+                 * outside BN_BLINDING. */
                 int ret;
                 CRYPTO_w_lock(CRYPTO_LOCK_RSA_BLINDING);
-                ret = BN_BLINDING_invert_ex(f, r, b, ctx);
+                ret = BN_BLINDING_convert_ex(f, unblind, b, ctx);
                 CRYPTO_w_unlock(CRYPTO_LOCK_RSA_BLINDING);
                 return ret;
                 }
-}
+        }
+
+static int rsa_blinding_invert(BN_BLINDING *b, BIGNUM *f, BIGNUM *unblind,
+        BN_CTX *ctx)
+        {
+        /* For local blinding, unblind is set to NULL, and BN_BLINDING_invert_ex
+         * will use the unblinding factor stored in BN_BLINDING.
+         * If BN_BLINDING is shared between threads, unblind must be non-null:
+         * BN_BLINDING_invert_ex will then use the local unblinding factor,
+         * and will only read the modulus from BN_BLINDING.
+         * In both cases it's safe to access the blinding without a lock.
+         */
+        return BN_BLINDING_invert_ex(f, unblind, b, ctx);
+        }
 
 /* signing */
 static int RSA_eay_private_encrypt(int flen, const unsigned char *from,
              unsigned char *to, RSA *rsa, int padding)
         {
-        BIGNUM *f, *ret, *br, *res;
+        BIGNUM *f, *ret, *res;
         int i,j,k,num=0,r= -1;
         unsigned char *buf=NULL;
         BN_CTX *ctx=NULL;
         int local_blinding = 0;
+        /* Used only if the blinding structure is shared. A non-NULL unblind
+         * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
+         * the unblinding factor outside the blinding structure. */
+        BIGNUM *unblind = NULL;
         BN_BLINDING *blinding = NULL;
 
         if ((ctx=BN_CTX_new()) == NULL) goto err;
         BN_CTX_start(ctx);
         f   = BN_CTX_get(ctx);
-        br  = BN_CTX_get(ctx);
         ret = BN_CTX_get(ctx);
         num = BN_num_bytes(rsa->n);
         buf = OPENSSL_malloc(num);
@@ -406,8 +411,15 @@ static int RSA_eay_private_encrypt(int flen, const unsigned char *from,
                 }
         
         if (blinding != NULL)
-                if (!rsa_blinding_convert(blinding, local_blinding, f, br, ctx))
+                {
+                if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL))
+                        {
+                        RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT,ERR_R_MALLOC_FAILURE);
+                        goto err;
+                        }
+                if (!rsa_blinding_convert(blinding, f, unblind, ctx))
                         goto err;
+                }
 
         if ( (rsa->flags & RSA_FLAG_EXT_PKEY) ||
                 ((rsa->p != NULL) &&
@@ -441,7 +453,7 @@ static int RSA_eay_private_encrypt(int flen, const unsigned char *from,
                 }
 
         if (blinding)
-                if (!rsa_blinding_invert(blinding, local_blinding, ret, br, ctx))
+                if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
                         goto err;
 
         if (padding == RSA_X931_PADDING)
@@ -480,18 +492,21 @@ err:
 static int RSA_eay_private_decrypt(int flen, const unsigned char *from,
              unsigned char *to, RSA *rsa, int padding)
         {
-        BIGNUM *f, *ret, *br;
+        BIGNUM *f, *ret;
         int j,num=0,r= -1;
         unsigned char *p;
         unsigned char *buf=NULL;
         BN_CTX *ctx=NULL;
         int local_blinding = 0;
+        /* Used only if the blinding structure is shared. A non-NULL unblind
+         * instructs rsa_blinding_convert() and rsa_blinding_invert() to store
+         * the unblinding factor outside the blinding structure. */
+        BIGNUM *unblind = NULL;
         BN_BLINDING *blinding = NULL;
 
         if((ctx = BN_CTX_new()) == NULL) goto err;
         BN_CTX_start(ctx);
         f   = BN_CTX_get(ctx);
-        br  = BN_CTX_get(ctx);
         ret = BN_CTX_get(ctx);
         num = BN_num_bytes(rsa->n);
         buf = OPENSSL_malloc(num);
@@ -529,8 +544,15 @@ static int RSA_eay_private_decrypt(int flen, const unsigned char *from,
                 }
         
         if (blinding != NULL)
-                if (!rsa_blinding_convert(blinding, local_blinding, f, br, ctx))
+                {
+                if (!local_blinding && ((unblind = BN_CTX_get(ctx)) == NULL))
+                        {
+                        RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT,ERR_R_MALLOC_FAILURE);
                         goto err;
+                        }
+                if (!rsa_blinding_convert(blinding, f, unblind, ctx))
+                        goto err;
+                }
 
         /* do the decrypt */
         if ( (rsa->flags & RSA_FLAG_EXT_PKEY) ||
@@ -564,7 +586,7 @@ static int RSA_eay_private_decrypt(int flen, const unsigned char *from,
                 }
 
         if (blinding)
-                if (!rsa_blinding_invert(blinding, local_blinding, ret, br, ctx))
+                if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
                         goto err;
 
         p=buf;