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Message-ID: <149147415660.21583.1680043566332938745.stgit@warthog.procyon.org.uk>
Date: Thu, 06 Apr 2017 11:22:36 +0100
From: David Howells <dhowells@...hat.com>
To: netdev@...r.kernel.org
Cc: dhowells@...hat.com, linux-afs@...ts.infradead.org,
linux-kernel@...r.kernel.org
Subject: [PATCH net-next 3/7] rxrpc: Handle temporary errors better in rxkad
security
In the rxkad security module, when we encounter a temporary error (such as
ENOMEM) from which we could conceivably recover, don't abort the
connection, but rather permit retransmission of the relevant packets to
induce a retry.
Note that I'm leaving some places that could be merged together to insert
tracing in the next patch.
Signed-off-by; David Howells <dhowells@...hat.com>
---
net/rxrpc/rxkad.c | 78 +++++++++++++++++++++++++++--------------------------
1 file changed, 40 insertions(+), 38 deletions(-)
diff --git a/net/rxrpc/rxkad.c b/net/rxrpc/rxkad.c
index 2d5838a3dc24..988903f1dc80 100644
--- a/net/rxrpc/rxkad.c
+++ b/net/rxrpc/rxkad.c
@@ -759,16 +759,14 @@ static int rxkad_respond_to_challenge(struct rxrpc_connection *conn,
_enter("{%d,%x}", conn->debug_id, key_serial(conn->params.key));
- if (!conn->params.key) {
- _leave(" = -EPROTO [no key]");
- return -EPROTO;
- }
+ abort_code = RX_PROTOCOL_ERROR;
+ if (!conn->params.key)
+ goto protocol_error;
+ abort_code = RXKADEXPIRED;
ret = key_validate(conn->params.key);
- if (ret < 0) {
- *_abort_code = RXKADEXPIRED;
- return ret;
- }
+ if (ret < 0)
+ goto other_error;
abort_code = RXKADPACKETSHORT;
if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
@@ -787,8 +785,9 @@ static int rxkad_respond_to_challenge(struct rxrpc_connection *conn,
goto protocol_error;
abort_code = RXKADLEVELFAIL;
+ ret = -EACCES;
if (conn->params.security_level < min_level)
- goto protocol_error;
+ goto other_error;
token = conn->params.key->payload.data[0];
@@ -815,9 +814,10 @@ static int rxkad_respond_to_challenge(struct rxrpc_connection *conn,
return rxkad_send_response(conn, &sp->hdr, &resp, token->kad);
protocol_error:
+ ret = -EPROTO;
+other_error:
*_abort_code = abort_code;
- _leave(" = -EPROTO [%d]", abort_code);
- return -EPROTO;
+ return ret;
}
/*
@@ -848,10 +848,10 @@ static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
switch (ret) {
case -EKEYEXPIRED:
*_abort_code = RXKADEXPIRED;
- goto error;
+ goto other_error;
default:
*_abort_code = RXKADNOAUTH;
- goto error;
+ goto other_error;
}
}
@@ -860,13 +860,11 @@ static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
memcpy(&iv, &conn->server_key->payload.data[2], sizeof(iv));
+ ret = -ENOMEM;
req = skcipher_request_alloc(conn->server_key->payload.data[0],
GFP_NOFS);
- if (!req) {
- *_abort_code = RXKADNOAUTH;
- ret = -ENOMEM;
- goto error;
- }
+ if (!req)
+ goto temporary_error;
sg_init_one(&sg[0], ticket, ticket_len);
skcipher_request_set_callback(req, 0, NULL, NULL);
@@ -943,13 +941,13 @@ static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
if (issue > now) {
*_abort_code = RXKADNOAUTH;
ret = -EKEYREJECTED;
- goto error;
+ goto other_error;
}
if (issue < now - life) {
*_abort_code = RXKADEXPIRED;
ret = -EKEYEXPIRED;
- goto error;
+ goto other_error;
}
*_expiry = issue + life;
@@ -961,16 +959,15 @@ static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
/* get the service instance name */
name = Z(INST_SZ);
_debug("KIV SINST: %s", name);
-
- ret = 0;
-error:
- _leave(" = %d", ret);
- return ret;
+ return 0;
bad_ticket:
*_abort_code = RXKADBADTICKET;
- ret = -EBADMSG;
- goto error;
+ ret = -EPROTO;
+other_error:
+ return ret;
+temporary_error:
+ return ret;
}
/*
@@ -1054,9 +1051,10 @@ static int rxkad_verify_response(struct rxrpc_connection *conn,
goto protocol_error;
/* extract the kerberos ticket and decrypt and decode it */
+ ret = -ENOMEM;
ticket = kmalloc(ticket_len, GFP_NOFS);
if (!ticket)
- return -ENOMEM;
+ goto temporary_error;
abort_code = RXKADPACKETSHORT;
if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
@@ -1064,12 +1062,9 @@ static int rxkad_verify_response(struct rxrpc_connection *conn,
goto protocol_error_free;
ret = rxkad_decrypt_ticket(conn, ticket, ticket_len, &session_key,
- &expiry, &abort_code);
- if (ret < 0) {
- *_abort_code = abort_code;
- kfree(ticket);
- return ret;
- }
+ &expiry, _abort_code);
+ if (ret < 0)
+ goto temporary_error_free;
/* use the session key from inside the ticket to decrypt the
* response */
@@ -1123,10 +1118,8 @@ static int rxkad_verify_response(struct rxrpc_connection *conn,
* this the connection security can be handled in exactly the same way
* as for a client connection */
ret = rxrpc_get_server_data_key(conn, &session_key, expiry, kvno);
- if (ret < 0) {
- kfree(ticket);
- return ret;
- }
+ if (ret < 0)
+ goto temporary_error_free;
kfree(ticket);
_leave(" = 0");
@@ -1140,6 +1133,15 @@ static int rxkad_verify_response(struct rxrpc_connection *conn,
*_abort_code = abort_code;
_leave(" = -EPROTO [%d]", abort_code);
return -EPROTO;
+
+temporary_error_free:
+ kfree(ticket);
+temporary_error:
+ /* Ignore the response packet if we got a temporary error such as
+ * ENOMEM. We just want to send the challenge again. Note that we
+ * also come out this way if the ticket decryption fails.
+ */
+ return ret;
}
/*
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