SUNRPC: Use a static buffer for the checksum initialization vector

Allocating and zeroing a buffer during every call to
krb5_etm_checksum() is inefficient. Instead, set aside a static
buffer that is the maximum crypto block size, and use a portion
(or all) of that.

Reported-by: Markus Elfring <Markus.Elfring@web.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/net/sunrpc/auth_gss/gss_krb5_crypto.c b/net/sunrpc/auth_gss/gss_krb5_crypto.c
index d2b02710ab0709dfc92b4ce8e1bc0d892016594e..b2c1b683a88ee2ece3f5f84ff0af7468f437e13b 100644 (file)
--- a/net/sunrpc/auth_gss/gss_krb5_crypto.c
+++ b/net/sunrpc/auth_gss/gss_krb5_crypto.c
@@ -921,6 +921,8 @@ out_err:
  * Caller provides the truncation length of the output token (h) in
  * cksumout.len.
  *
+ * Note that for RPCSEC, the "initial cipher state" is always all zeroes.
+ *
  * Return values:
  *   %GSS_S_COMPLETE: Digest computed, @cksumout filled in
  *   %GSS_S_FAILURE: Call failed
@@ -931,22 +933,19 @@ u32 krb5_etm_checksum(struct crypto_sync_skcipher *cipher,
                      int body_offset, struct xdr_netobj *cksumout)
 {
        unsigned int ivsize = crypto_sync_skcipher_ivsize(cipher);
+       static const u8 iv[GSS_KRB5_MAX_BLOCKSIZE];
        struct ahash_request *req;
        struct scatterlist sg[1];
-       u8 *iv, *checksumdata;
        int err = -ENOMEM;
+       u8 *checksumdata;
 
        checksumdata = kmalloc(crypto_ahash_digestsize(tfm), GFP_KERNEL);
        if (!checksumdata)
                return GSS_S_FAILURE;
-       /* For RPCSEC, the "initial cipher state" is always all zeroes. */
-       iv = kzalloc(ivsize, GFP_KERNEL);
-       if (!iv)
-               goto out_free_mem;
 
        req = ahash_request_alloc(tfm, GFP_KERNEL);
        if (!req)
-               goto out_free_mem;
+               goto out_free_cksumdata;
        ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
        err = crypto_ahash_init(req);
        if (err)
@@ -970,8 +969,7 @@ u32 krb5_etm_checksum(struct crypto_sync_skcipher *cipher,
 
 out_free_ahash:
        ahash_request_free(req);
-out_free_mem:
-       kfree(iv);
+out_free_cksumdata:
        kfree_sensitive(checksumdata);
        return err ? GSS_S_FAILURE : GSS_S_COMPLETE;
 }