[PATCH net v5 16/21] rxrpc: Fix missing error checks for rxkad encryption/decryption failure

[David Howells <dhowells@redhat.com>]

Add error checking for failure of crypto_skcipher_en/decrypt() to various
rxkad function as the crypto functions can fail with ENOMEM at least.

Fixes: 17926a79320a ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both")
Closes: https://sashiko.dev/#/patchset/20260401105614.1696001-10-dhowells@redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Jeffrey Altman <jaltman@auristor.com>
cc: Eric Dumazet <edumazet@google.com>
cc: "David S. Miller" <davem@davemloft.net>
cc: Jakub Kicinski <kuba@kernel.org>
cc: Paolo Abeni <pabeni@redhat.com>
cc: Simon Horman <horms@kernel.org>
cc: linux-afs@lists.infradead.org
cc: netdev@vger.kernel.org
cc: stable@kernel.org
---
 net/rxrpc/rxkad.c | 57 +++++++++++++++++++++++++++++++----------------
 1 file changed, 38 insertions(+), 19 deletions(-)

diff --git a/net/rxrpc/rxkad.c b/net/rxrpc/rxkad.c
index 0f79d694cb08..eb7f2769d2b1 100644
--- a/net/rxrpc/rxkad.c
+++ b/net/rxrpc/rxkad.c
@@ -197,6 +197,7 @@ static int rxkad_prime_packet_security(struct rxrpc_connection *conn,
 	struct rxrpc_crypt iv;
 	__be32 *tmpbuf;
 	size_t tmpsize = 4 * sizeof(__be32);
+	int ret;
 
 	_enter("");
 
@@ -225,13 +226,13 @@ static int rxkad_prime_packet_security(struct rxrpc_connection *conn,
 	skcipher_request_set_sync_tfm(req, ci);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, &sg, &sg, tmpsize, iv.x);
-	crypto_skcipher_encrypt(req);
+	ret = crypto_skcipher_encrypt(req);
 	skcipher_request_free(req);
 
 	memcpy(&conn->rxkad.csum_iv, tmpbuf + 2, sizeof(conn->rxkad.csum_iv));
 	kfree(tmpbuf);
-	_leave(" = 0");
-	return 0;
+	_leave(" = %d", ret);
+	return ret;
 }
 
 /*
@@ -264,6 +265,7 @@ static int rxkad_secure_packet_auth(const struct rxrpc_call *call,
 	struct scatterlist sg;
 	size_t pad;
 	u16 check;
+	int ret;
 
 	_enter("");
 
@@ -286,11 +288,11 @@ static int rxkad_secure_packet_auth(const struct rxrpc_call *call,
 	skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
-	crypto_skcipher_encrypt(req);
+	ret = crypto_skcipher_encrypt(req);
 	skcipher_request_zero(req);
 
-	_leave(" = 0");
-	return 0;
+	_leave(" = %d", ret);
+	return ret;
 }
 
 /*
@@ -345,7 +347,7 @@ static int rxkad_secure_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
 	union {
 		__be32 buf[2];
 	} crypto __aligned(8);
-	u32 x, y;
+	u32 x, y = 0;
 	int ret;
 
 	_enter("{%d{%x}},{#%u},%u,",
@@ -376,8 +378,10 @@ static int rxkad_secure_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
 	skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
-	crypto_skcipher_encrypt(req);
+	ret = crypto_skcipher_encrypt(req);
 	skcipher_request_zero(req);
+	if (ret < 0)
+		goto out;
 
 	y = ntohl(crypto.buf[1]);
 	y = (y >> 16) & 0xffff;
@@ -413,6 +417,7 @@ static int rxkad_secure_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
 		memset(p + txb->pkt_len, 0, gap);
 	}
 
+out:
 	skcipher_request_free(req);
 	_leave(" = %d [set %x]", ret, y);
 	return ret;
@@ -453,8 +458,10 @@ static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb,
 	skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, sg, sg, 8, iv.x);
-	crypto_skcipher_decrypt(req);
+	ret = crypto_skcipher_decrypt(req);
 	skcipher_request_zero(req);
+	if (ret < 0)
+		return ret;
 
 	/* Extract the decrypted packet length */
 	if (skb_copy_bits(skb, sp->offset, &sechdr, sizeof(sechdr)) < 0)
@@ -531,10 +538,14 @@ static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb,
 	skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, sg, sg, sp->len, iv.x);
-	crypto_skcipher_decrypt(req);
+	ret = crypto_skcipher_decrypt(req);
 	skcipher_request_zero(req);
 	if (sg != _sg)
 		kfree(sg);
+	if (ret < 0) {
+		WARN_ON_ONCE(ret != -ENOMEM);
+		return ret;
+	}
 
 	/* Extract the decrypted packet length */
 	if (skb_copy_bits(skb, sp->offset, &sechdr, sizeof(sechdr)) < 0)
@@ -602,8 +613,10 @@ static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb)
 	skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
-	crypto_skcipher_encrypt(req);
+	ret = crypto_skcipher_encrypt(req);
 	skcipher_request_zero(req);
+	if (ret < 0)
+		goto out;
 
 	y = ntohl(crypto.buf[1]);
 	cksum = (y >> 16) & 0xffff;
@@ -1077,21 +1090,23 @@ static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
 /*
  * decrypt the response packet
  */
-static void rxkad_decrypt_response(struct rxrpc_connection *conn,
-				   struct rxkad_response *resp,
-				   const struct rxrpc_crypt *session_key)
+static int rxkad_decrypt_response(struct rxrpc_connection *conn,
+				  struct rxkad_response *resp,
+				  const struct rxrpc_crypt *session_key)
 {
 	struct skcipher_request *req = rxkad_ci_req;
 	struct scatterlist sg[1];
 	struct rxrpc_crypt iv;
+	int ret;
 
 	_enter(",,%08x%08x",
 	       ntohl(session_key->n[0]), ntohl(session_key->n[1]));
 
 	mutex_lock(&rxkad_ci_mutex);
-	if (crypto_sync_skcipher_setkey(rxkad_ci, session_key->x,
-					sizeof(*session_key)) < 0)
-		BUG();
+	ret = crypto_sync_skcipher_setkey(rxkad_ci, session_key->x,
+					  sizeof(*session_key));
+	if (ret < 0)
+		goto unlock;
 
 	memcpy(&iv, session_key, sizeof(iv));
 
@@ -1100,12 +1115,14 @@ static void rxkad_decrypt_response(struct rxrpc_connection *conn,
 	skcipher_request_set_sync_tfm(req, rxkad_ci);
 	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
-	crypto_skcipher_decrypt(req);
+	ret = crypto_skcipher_decrypt(req);
 	skcipher_request_zero(req);
 
+unlock:
 	mutex_unlock(&rxkad_ci_mutex);
 
 	_leave("");
+	return ret;
 }
 
 /*
@@ -1198,7 +1215,9 @@ static int rxkad_verify_response(struct rxrpc_connection *conn,
 
 	/* use the session key from inside the ticket to decrypt the
 	 * response */
-	rxkad_decrypt_response(conn, response, &session_key);
+	ret = rxkad_decrypt_response(conn, response, &session_key);
+	if (ret < 0)
+		goto temporary_error_free_ticket;
 
 	if (ntohl(response->encrypted.epoch) != conn->proto.epoch ||
 	    ntohl(response->encrypted.cid) != conn->proto.cid ||