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rxrpc: Handle temporary errors better in rxkad security

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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@redhat.com>
This commit is contained in:
David Howells 2017-04-06 10:11:59 +01:00
parent 84a4c09c38
commit ef68622da9
1 changed files with 40 additions and 38 deletions
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78
net/rxrpc/rxkad.c
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@ -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 @@ protocol_error:
*_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;
}
/*