sunrpc: remove incorrect HMAC request initialization

make_checksum_hmac_md5() is allocating an HMAC transform and doing crypto API calls in the following order:

crypto_ahash_init()
crypto_ahash_setkey()
crypto_ahash_digest()

This is wrong because it makes no sense to init() the request before a key has been set, given that the initial state depends on the key. And digest() is short for init() + update() + final(), so in this case there's no need to explicitly call init() at all.

Before commit 9fa68f620041 ("crypto: hash - prevent using keyed hashes without setting key") the extra init() had no real effect, at least for the software HMAC implementation. (There are also hardware drivers that implement HMAC-MD5, and it's not immediately obvious how gracefully they handle init() before setkey().) But now the crypto API detects this incorrect initialization and returns -ENOKEY. This is breaking NFS mounts in some cases.

Fix it by removing the incorrect call to crypto_ahash_init().

Reported-by Michael Young <[email protected]>

Fixes 9fa68f620041 ("crypto: hash - prevent using keyed hashes without setting key")

Fixes fffdaef2eb4a ("gss_krb5: Add support for rc4-hmac encryption")

Cc [email protected]

Signed-off-by Eric Biggers <[email protected]>

---
 net/sunrpc/auth_gss/gss_krb5_crypto.c | 3 ---
 1 file changed, 3 deletions(-)

net/sunrpc/auth_gss/gss_krb5_crypto.c +0 -3

index 12649c9fedab..8654494b4d0a 100644
@@ -237,9 +237,6 @@ make_checksum_hmac_md5(struct krb5_ctx *kctx, char *header, int hdrlen,
 
 	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
 
-	err = crypto_ahash_init(req);
-	if (err)
-		goto out;
 	err = crypto_ahash_setkey(hmac_md5, cksumkey, kctx->gk5e->keylength);
 	if (err)
 		goto out;

Signature · 1 line

2.17.0.rc1.321.gba9d0f2565-goog