crypto: krb5enc - fix async decrypt skipping hash verification

krb5enc_dispatch_decrypt() sets req->base.complete as the skcipher
callback, which is the caller's own completion handler. When the
skcipher completes asynchronously, this signals "done" to the caller
without executing krb5enc_dispatch_decrypt_hash(), completely bypassing
the integrity verification (hash check).

Compare with the encrypt path which correctly uses
krb5enc_encrypt_done as an intermediate callback to chain into the
hash computation on async completion.

Fix by adding krb5enc_decrypt_done as an intermediate callback that
chains into krb5enc_dispatch_decrypt_hash() upon async skcipher
completion, matching the encrypt path's callback pattern.

Also fix EBUSY/EINPROGRESS handling throughout: remove
krb5enc_request_complete() which incorrectly swallowed EINPROGRESS
notifications that must be passed up to callers waiting on backlogged
requests, and add missing EBUSY checks in krb5enc_encrypt_ahash_done
for the dispatch_encrypt return value.

Fixes: d1775a177f7f ("crypto: Add 'krb5enc' hash and cipher AEAD algorithm")
Signed-off-by: Dudu Lu <phx0fer@gmail.com>
Unset MAY_BACKLOG on the async completion path so the user won't
see back-to-back EINPROGRESS notifications.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/krb5enc.c b/crypto/krb5enc.c
index 1bfe8370cf94883c66a4ecd5fc8d2e57c6975980..fefa8d2c7532251d365eb51ae65acded151e7417 100644 (file)
--- a/crypto/krb5enc.c
+++ b/crypto/krb5enc.c
@@ -39,12 +39,6 @@ struct krb5enc_request_ctx {
        char tail[];
 };
 
-static void krb5enc_request_complete(struct aead_request *req, int err)
-{
-       if (err != -EINPROGRESS)
-               aead_request_complete(req, err);
-}
-
 /**
  * crypto_krb5enc_extractkeys - Extract Ke and Ki keys from the key blob.
  * @keys: Where to put the key sizes and pointers
@@ -127,7 +121,7 @@ static void krb5enc_encrypt_done(void *data, int err)
 {
        struct aead_request *req = data;
 
-       krb5enc_request_complete(req, err);
+       aead_request_complete(req, err);
 }
 
 /*
@@ -188,14 +182,16 @@ static void krb5enc_encrypt_ahash_done(void *data, int err)
        struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 
        if (err)
-               return krb5enc_request_complete(req, err);
+               goto out;
 
        krb5enc_insert_checksum(req, ahreq->result);
 
-       err = krb5enc_dispatch_encrypt(req,
-                                      aead_request_flags(req) & ~CRYPTO_TFM_REQ_MAY_SLEEP);
-       if (err != -EINPROGRESS)
-               aead_request_complete(req, err);
+       err = krb5enc_dispatch_encrypt(req, 0);
+       if (err == -EINPROGRESS)
+               return;
+
+out:
+       aead_request_complete(req, err);
 }
 
 /*
@@ -265,17 +261,16 @@ static void krb5enc_decrypt_hash_done(void *data, int err)
 {
        struct aead_request *req = data;
 
-       if (err)
-               return krb5enc_request_complete(req, err);
-
-       err = krb5enc_verify_hash(req);
-       krb5enc_request_complete(req, err);
+       if (!err)
+               err = krb5enc_verify_hash(req);
+       aead_request_complete(req, err);
 }
 
 /*
  * Dispatch the hashing of the plaintext after we've done the decryption.
  */
-static int krb5enc_dispatch_decrypt_hash(struct aead_request *req)
+static int krb5enc_dispatch_decrypt_hash(struct aead_request *req,
+                                        unsigned int flags)
 {
        struct crypto_aead *krb5enc = crypto_aead_reqtfm(req);
        struct aead_instance *inst = aead_alg_instance(krb5enc);
@@ -291,7 +286,7 @@ static int krb5enc_dispatch_decrypt_hash(struct aead_request *req)
        ahash_request_set_tfm(ahreq, auth);
        ahash_request_set_crypt(ahreq, req->dst, hash,
                                req->assoclen + req->cryptlen - authsize);
-       ahash_request_set_callback(ahreq, aead_request_flags(req),
+       ahash_request_set_callback(ahreq, flags,
                                   krb5enc_decrypt_hash_done, req);
 
        err = crypto_ahash_digest(ahreq);
@@ -301,6 +296,21 @@ static int krb5enc_dispatch_decrypt_hash(struct aead_request *req)
        return krb5enc_verify_hash(req);
 }
 
+static void krb5enc_decrypt_done(void *data, int err)
+{
+       struct aead_request *req = data;
+
+       if (err)
+               goto out;
+
+       err = krb5enc_dispatch_decrypt_hash(req, 0);
+       if (err == -EINPROGRESS)
+               return;
+
+out:
+       aead_request_complete(req, err);
+}
+
 /*
  * Dispatch the decryption of the ciphertext.
  */
@@ -324,7 +334,7 @@ static int krb5enc_dispatch_decrypt(struct aead_request *req)
 
        skcipher_request_set_tfm(skreq, ctx->enc);
        skcipher_request_set_callback(skreq, aead_request_flags(req),
-                                     req->base.complete, req->base.data);
+                                     krb5enc_decrypt_done, req);
        skcipher_request_set_crypt(skreq, src, dst,
                                   req->cryptlen - authsize, req->iv);
 
@@ -339,7 +349,7 @@ static int krb5enc_decrypt(struct aead_request *req)
        if (err < 0)
                return err;
 
-       return krb5enc_dispatch_decrypt_hash(req);
+       return krb5enc_dispatch_decrypt_hash(req, aead_request_flags(req));
 }
 
 static int krb5enc_init_tfm(struct crypto_aead *tfm)