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authorDavid Howells <dhowells@redhat.com>2018-09-27 17:13:09 +0300
committerDavid Howells <dhowells@redhat.com>2018-09-28 12:32:49 +0300
commit0099dc589bfa7caf6f2608c4cbc1181cfee22b0c (patch)
treefd071d7aab3762ba2ab377892cb4c250923d50b8 /net/rxrpc/call_accept.c
parent403fc2a138457f1071b186786a7589ef7382c8bc (diff)
downloadlinux-0099dc589bfa7caf6f2608c4cbc1181cfee22b0c.tar.xz
rxrpc: Make service call handling more robust
Make the following changes to improve the robustness of the code that sets up a new service call: (1) Cache the rxrpc_sock struct obtained in rxrpc_data_ready() to do a service ID check and pass that along to rxrpc_new_incoming_call(). This means that I can remove the check from rxrpc_new_incoming_call() without the need to worry about the socket attached to the local endpoint getting replaced - which would invalidate the check. (2) Cache the rxrpc_peer struct, thereby allowing the peer search to be done once. The peer is passed to rxrpc_new_incoming_call(), thereby saving the need to repeat the search. This also reduces the possibility of rxrpc_publish_service_conn() BUG()'ing due to the detection of a duplicate connection, despite the initial search done by rxrpc_find_connection_rcu() having turned up nothing. This BUG() shouldn't ever get hit since rxrpc_data_ready() *should* be non-reentrant and the result of the initial search should still hold true, but it has proven possible to hit. I *think* this may be due to __rxrpc_lookup_peer_rcu() cutting short the iteration over the hash table if it finds a matching peer with a zero usage count, but I don't know for sure since it's only ever been hit once that I know of. Another possibility is that a bug in rxrpc_data_ready() that checked the wrong byte in the header for the RXRPC_CLIENT_INITIATED flag might've let through a packet that caused a spurious and invalid call to be set up. That is addressed in another patch. (3) Fix __rxrpc_lookup_peer_rcu() to skip peer records that have a zero usage count rather than stopping and returning not found, just in case there's another peer record behind it in the bucket. (4) Don't search the peer records in rxrpc_alloc_incoming_call(), but rather either use the peer cached in (2) or, if one wasn't found, preemptively install a new one. Fixes: 8496af50eb38 ("rxrpc: Use RCU to access a peer's service connection tree") Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'net/rxrpc/call_accept.c')
-rw-r--r--net/rxrpc/call_accept.c41
1 files changed, 12 insertions, 29 deletions
diff --git a/net/rxrpc/call_accept.c b/net/rxrpc/call_accept.c
index e88f131c1d7f..9c7f26d06a52 100644
--- a/net/rxrpc/call_accept.c
+++ b/net/rxrpc/call_accept.c
@@ -249,11 +249,11 @@ void rxrpc_discard_prealloc(struct rxrpc_sock *rx)
*/
static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx,
struct rxrpc_local *local,
+ struct rxrpc_peer *peer,
struct rxrpc_connection *conn,
struct sk_buff *skb)
{
struct rxrpc_backlog *b = rx->backlog;
- struct rxrpc_peer *peer, *xpeer;
struct rxrpc_call *call;
unsigned short call_head, conn_head, peer_head;
unsigned short call_tail, conn_tail, peer_tail;
@@ -276,21 +276,18 @@ static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx,
return NULL;
if (!conn) {
- /* No connection. We're going to need a peer to start off
- * with. If one doesn't yet exist, use a spare from the
- * preallocation set. We dump the address into the spare in
- * anticipation - and to save on stack space.
- */
- xpeer = b->peer_backlog[peer_tail];
- if (rxrpc_extract_addr_from_skb(local, &xpeer->srx, skb) < 0)
- return NULL;
-
- peer = rxrpc_lookup_incoming_peer(local, xpeer);
- if (peer == xpeer) {
+ if (peer && !rxrpc_get_peer_maybe(peer))
+ peer = NULL;
+ if (!peer) {
+ peer = b->peer_backlog[peer_tail];
+ if (rxrpc_extract_addr_from_skb(local, &peer->srx, skb) < 0)
+ return NULL;
b->peer_backlog[peer_tail] = NULL;
smp_store_release(&b->peer_backlog_tail,
(peer_tail + 1) &
(RXRPC_BACKLOG_MAX - 1));
+
+ rxrpc_new_incoming_peer(local, peer);
}
/* Now allocate and set up the connection */
@@ -335,30 +332,16 @@ static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx,
* The call is returned with the user access mutex held.
*/
struct rxrpc_call *rxrpc_new_incoming_call(struct rxrpc_local *local,
+ struct rxrpc_sock *rx,
+ struct rxrpc_peer *peer,
struct rxrpc_connection *conn,
struct sk_buff *skb)
{
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
- struct rxrpc_sock *rx;
struct rxrpc_call *call;
- u16 service_id = sp->hdr.serviceId;
_enter("");
- /* Get the socket providing the service */
- rx = rcu_dereference(local->service);
- if (rx && (service_id == rx->srx.srx_service ||
- service_id == rx->second_service))
- goto found_service;
-
- trace_rxrpc_abort(0, "INV", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
- RX_INVALID_OPERATION, EOPNOTSUPP);
- skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
- skb->priority = RX_INVALID_OPERATION;
- _leave(" = NULL [service]");
- return NULL;
-
-found_service:
spin_lock(&rx->incoming_lock);
if (rx->sk.sk_state == RXRPC_SERVER_LISTEN_DISABLED ||
rx->sk.sk_state == RXRPC_CLOSE) {
@@ -371,7 +354,7 @@ found_service:
goto out;
}
- call = rxrpc_alloc_incoming_call(rx, local, conn, skb);
+ call = rxrpc_alloc_incoming_call(rx, local, peer, conn, skb);
if (!call) {
skb->mark = RXRPC_SKB_MARK_REJECT_BUSY;
_leave(" = NULL [busy]");