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341f741f04
linux/fs/afs/rxrpc.c
David Howells 341f741f04 afs: Refcount the afs_call struct 
A static checker warning occurs in the AFS filesystem:

	fs/afs/cmservice.c:155 SRXAFSCB_CallBack()
	error: dereferencing freed memory 'call'

due to the reply being sent before we access the server it points to.  The
act of sending the reply causes the call to be freed if an error occurs
(but not if it doesn't).

On top of this, the lifetime handling of afs_call structs is fragile
because they get passed around through workqueues without any sort of
refcounting.

Deal with the issues by:

 (1) Fix the maybe/maybe not nature of the reply sending functions with
     regards to whether they release the call struct.

 (2) Refcount the afs_call struct and sort out places that need to get/put
     references.

 (3) Pass a ref through the work queue and release (or pass on) that ref in
     the work function.  Care has to be taken because a work queue may
     already own a ref to the call.

 (4) Do the cleaning up in the put function only.

 (5) Simplify module cleanup by always incrementing afs_outstanding_calls
     whenever a call is allocated.

 (6) Set the backlog to 0 with kernel_listen() at the beginning of the
     process of closing the socket to prevent new incoming calls from
     occurring and to remove the contribution of preallocated calls from
     afs_outstanding_calls before we wait on it.

A tracepoint is also added to monitor the afs_call refcount and lifetime.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Fixes: 08e0e7c82e: "[AF_RXRPC]: Make the in-kernel AFS filesystem use AF_RXRPC."
2017-01-09 11:10:02 +00:00

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/* Maintain an RxRPC server socket to do AFS communications through
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/slab.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include <rxrpc/packet.h>
#include "internal.h"
#include "afs_cm.h"
struct socket *afs_socket; /* my RxRPC socket */
static struct workqueue_struct *afs_async_calls;
static struct afs_call *afs_spare_incoming_call;
atomic_t afs_outstanding_calls;
static void afs_wake_up_call_waiter(struct sock *, struct rxrpc_call *, unsigned long);
static int afs_wait_for_call_to_complete(struct afs_call *);
static void afs_wake_up_async_call(struct sock *, struct rxrpc_call *, unsigned long);
static void afs_process_async_call(struct work_struct *);
static void afs_rx_new_call(struct sock *, struct rxrpc_call *, unsigned long);
static void afs_rx_discard_new_call(struct rxrpc_call *, unsigned long);
static int afs_deliver_cm_op_id(struct afs_call *);
/* asynchronous incoming call initial processing */
static const struct afs_call_type afs_RXCMxxxx = {
.name = "CB.xxxx",
.deliver = afs_deliver_cm_op_id,
.abort_to_error = afs_abort_to_error,
};
static void afs_charge_preallocation(struct work_struct *);
static DECLARE_WORK(afs_charge_preallocation_work, afs_charge_preallocation);
static int afs_wait_atomic_t(atomic_t *p)
{
schedule();
return 0;
}
/*
* open an RxRPC socket and bind it to be a server for callback notifications
* - the socket is left in blocking mode and non-blocking ops use MSG_DONTWAIT
*/
int afs_open_socket(void)
{
struct sockaddr_rxrpc srx;
struct socket *socket;
int ret;
_enter("");
ret = -ENOMEM;
afs_async_calls = alloc_workqueue("kafsd", WQ_MEM_RECLAIM, 0);
if (!afs_async_calls)
goto error_0;
ret = sock_create_kern(&init_net, AF_RXRPC, SOCK_DGRAM, PF_INET, &socket);
if (ret < 0)
goto error_1;
socket->sk->sk_allocation = GFP_NOFS;
/* bind the callback manager's address to make this a server socket */
srx.srx_family = AF_RXRPC;
srx.srx_service = CM_SERVICE;
srx.transport_type = SOCK_DGRAM;
srx.transport_len = sizeof(srx.transport.sin);
srx.transport.sin.sin_family = AF_INET;
srx.transport.sin.sin_port = htons(AFS_CM_PORT);
memset(&srx.transport.sin.sin_addr, 0,
sizeof(srx.transport.sin.sin_addr));
ret = kernel_bind(socket, (struct sockaddr *) &srx, sizeof(srx));
if (ret < 0)
goto error_2;
rxrpc_kernel_new_call_notification(socket, afs_rx_new_call,
afs_rx_discard_new_call);
ret = kernel_listen(socket, INT_MAX);
if (ret < 0)
goto error_2;
afs_socket = socket;
afs_charge_preallocation(NULL);
_leave(" = 0");
return 0;
error_2:
sock_release(socket);
error_1:
destroy_workqueue(afs_async_calls);
error_0:
_leave(" = %d", ret);
return ret;
}
/*
* close the RxRPC socket AFS was using
*/
void afs_close_socket(void)
{
_enter("");
kernel_listen(afs_socket, 0);
flush_workqueue(afs_async_calls);
if (afs_spare_incoming_call) {
afs_put_call(afs_spare_incoming_call);
afs_spare_incoming_call = NULL;
}
_debug("outstanding %u", atomic_read(&afs_outstanding_calls));
wait_on_atomic_t(&afs_outstanding_calls, afs_wait_atomic_t,
TASK_UNINTERRUPTIBLE);
_debug("no outstanding calls");
kernel_sock_shutdown(afs_socket, SHUT_RDWR);
flush_workqueue(afs_async_calls);
sock_release(afs_socket);
_debug("dework");
destroy_workqueue(afs_async_calls);
_leave("");
}
/*
* Allocate a call.
*/
static struct afs_call *afs_alloc_call(const struct afs_call_type *type,
gfp_t gfp)
{
struct afs_call *call;
int o;
call = kzalloc(sizeof(*call), gfp);
if (!call)
return NULL;
call->type = type;
atomic_set(&call->usage, 1);
INIT_WORK(&call->async_work, afs_process_async_call);
init_waitqueue_head(&call->waitq);
o = atomic_inc_return(&afs_outstanding_calls);
trace_afs_call(call, afs_call_trace_alloc, 1, o,
__builtin_return_address(0));
return call;
}
/*
* Dispose of a reference on a call.
*/
void afs_put_call(struct afs_call *call)
{
int n = atomic_dec_return(&call->usage);
int o = atomic_read(&afs_outstanding_calls);
trace_afs_call(call, afs_call_trace_put, n + 1, o,
__builtin_return_address(0));
ASSERTCMP(n, >=, 0);
if (n == 0) {
ASSERT(!work_pending(&call->async_work));
ASSERT(call->type->name != NULL);
if (call->rxcall) {
rxrpc_kernel_end_call(afs_socket, call->rxcall);
call->rxcall = NULL;
}
if (call->type->destructor)
call->type->destructor(call);
kfree(call->request);
kfree(call);
o = atomic_dec_return(&afs_outstanding_calls);
trace_afs_call(call, afs_call_trace_free, 0, o,
__builtin_return_address(0));
if (o == 0)
wake_up_atomic_t(&afs_outstanding_calls);
}
}
/*
* Queue the call for actual work. Returns 0 unconditionally for convenience.
*/
int afs_queue_call_work(struct afs_call *call)
{
int u = atomic_inc_return(&call->usage);
trace_afs_call(call, afs_call_trace_work, u,
atomic_read(&afs_outstanding_calls),
__builtin_return_address(0));
INIT_WORK(&call->work, call->type->work);
if (!queue_work(afs_wq, &call->work))
afs_put_call(call);
return 0;
}
/*
* allocate a call with flat request and reply buffers
*/
struct afs_call *afs_alloc_flat_call(const struct afs_call_type *type,
size_t request_size, size_t reply_max)
{
struct afs_call *call;
call = afs_alloc_call(type, GFP_NOFS);
if (!call)
goto nomem_call;
if (request_size) {
call->request_size = request_size;
call->request = kmalloc(request_size, GFP_NOFS);
if (!call->request)
goto nomem_free;
}
if (reply_max) {
call->reply_max = reply_max;
call->buffer = kmalloc(reply_max, GFP_NOFS);
if (!call->buffer)
goto nomem_free;
}
init_waitqueue_head(&call->waitq);
return call;
nomem_free:
afs_put_call(call);
nomem_call:
return NULL;
}
/*
* clean up a call with flat buffer
*/
void afs_flat_call_destructor(struct afs_call *call)
{
_enter("");
kfree(call->request);
call->request = NULL;
kfree(call->buffer);
call->buffer = NULL;
}
/*
* attach the data from a bunch of pages on an inode to a call
*/
static int afs_send_pages(struct afs_call *call, struct msghdr *msg,
struct kvec *iov)
{
struct page *pages[8];
unsigned count, n, loop, offset, to;
pgoff_t first = call->first, last = call->last;
int ret;
_enter("");
offset = call->first_offset;
call->first_offset = 0;
do {
_debug("attach %lx-%lx", first, last);
count = last - first + 1;
if (count > ARRAY_SIZE(pages))
count = ARRAY_SIZE(pages);
n = find_get_pages_contig(call->mapping, first, count, pages);
ASSERTCMP(n, ==, count);
loop = 0;
do {
msg->msg_flags = 0;
to = PAGE_SIZE;
if (first + loop >= last)
to = call->last_to;
else
msg->msg_flags = MSG_MORE;
iov->iov_base = kmap(pages[loop]) + offset;
iov->iov_len = to - offset;
offset = 0;
_debug("- range %u-%u%s",
offset, to, msg->msg_flags ? " [more]" : "");
iov_iter_kvec(&msg->msg_iter, WRITE | ITER_KVEC,
iov, 1, to - offset);
/* have to change the state *before* sending the last
* packet as RxRPC might give us the reply before it
* returns from sending the request */
if (first + loop >= last)
call->state = AFS_CALL_AWAIT_REPLY;
ret = rxrpc_kernel_send_data(afs_socket, call->rxcall,
msg, to - offset);
kunmap(pages[loop]);
if (ret < 0)
break;
} while (++loop < count);
first += count;
for (loop = 0; loop < count; loop++)
put_page(pages[loop]);
if (ret < 0)
break;
} while (first <= last);
_leave(" = %d", ret);
return ret;
}
/*
* initiate a call
*/
int afs_make_call(struct in_addr *addr, struct afs_call *call, gfp_t gfp,
bool async)
{
struct sockaddr_rxrpc srx;
struct rxrpc_call *rxcall;
struct msghdr msg;
struct kvec iov[1];
int ret;
_enter("%x,{%d},", addr->s_addr, ntohs(call->port));
ASSERT(call->type != NULL);
ASSERT(call->type->name != NULL);
_debug("____MAKE %p{%s,%x} [%d]____",
call, call->type->name, key_serial(call->key),
atomic_read(&afs_outstanding_calls));
call->async = async;
memset(&srx, 0, sizeof(srx));
srx.srx_family = AF_RXRPC;
srx.srx_service = call->service_id;
srx.transport_type = SOCK_DGRAM;
srx.transport_len = sizeof(srx.transport.sin);
srx.transport.sin.sin_family = AF_INET;
srx.transport.sin.sin_port = call->port;
memcpy(&srx.transport.sin.sin_addr, addr, 4);
/* create a call */
rxcall = rxrpc_kernel_begin_call(afs_socket, &srx, call->key,
(unsigned long) call, gfp,
(async ?
afs_wake_up_async_call :
afs_wake_up_call_waiter));
call->key = NULL;
if (IS_ERR(rxcall)) {
ret = PTR_ERR(rxcall);
goto error_kill_call;
}
call->rxcall = rxcall;
/* send the request */
iov[0].iov_base = call->request;
iov[0].iov_len = call->request_size;
msg.msg_name = NULL;
msg.msg_namelen = 0;
iov_iter_kvec(&msg.msg_iter, WRITE | ITER_KVEC, iov, 1,
call->request_size);
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_flags = (call->send_pages ? MSG_MORE : 0);
/* have to change the state *before* sending the last packet as RxRPC
* might give us the reply before it returns from sending the
* request */
if (!call->send_pages)
call->state = AFS_CALL_AWAIT_REPLY;
ret = rxrpc_kernel_send_data(afs_socket, rxcall,
&msg, call->request_size);
if (ret < 0)
goto error_do_abort;
if (call->send_pages) {
ret = afs_send_pages(call, &msg, iov);
if (ret < 0)
goto error_do_abort;
}
/* at this point, an async call may no longer exist as it may have
* already completed */
if (call->async)
return -EINPROGRESS;
return afs_wait_for_call_to_complete(call);
error_do_abort:
rxrpc_kernel_abort_call(afs_socket, rxcall, RX_USER_ABORT, -ret, "KSD");
error_kill_call:
afs_put_call(call);
_leave(" = %d", ret);
return ret;
}
/*
* deliver messages to a call
*/
static void afs_deliver_to_call(struct afs_call *call)
{
u32 abort_code;
int ret;
_enter("%s", call->type->name);
while (call->state == AFS_CALL_AWAIT_REPLY ||
call->state == AFS_CALL_AWAIT_OP_ID ||
call->state == AFS_CALL_AWAIT_REQUEST ||
call->state == AFS_CALL_AWAIT_ACK
) {
if (call->state == AFS_CALL_AWAIT_ACK) {
size_t offset = 0;
ret = rxrpc_kernel_recv_data(afs_socket, call->rxcall,
NULL, 0, &offset, false,
&call->abort_code);
trace_afs_recv_data(call, 0, offset, false, ret);
if (ret == -EINPROGRESS || ret == -EAGAIN)
return;
if (ret == 1 || ret < 0) {
call->state = AFS_CALL_COMPLETE;
goto done;
}
return;
}
ret = call->type->deliver(call);
switch (ret) {
case 0:
if (call->state == AFS_CALL_AWAIT_REPLY)
call->state = AFS_CALL_COMPLETE;
goto done;
case -EINPROGRESS:
case -EAGAIN:
goto out;
case -ENOTCONN:
abort_code = RX_CALL_DEAD;
rxrpc_kernel_abort_call(afs_socket, call->rxcall,
abort_code, -ret, "KNC");
goto do_abort;
case -ENOTSUPP:
abort_code = RX_INVALID_OPERATION;
rxrpc_kernel_abort_call(afs_socket, call->rxcall,
abort_code, -ret, "KIV");
goto do_abort;
case -ENODATA:
case -EBADMSG:
case -EMSGSIZE:
default:
abort_code = RXGEN_CC_UNMARSHAL;
if (call->state != AFS_CALL_AWAIT_REPLY)
abort_code = RXGEN_SS_UNMARSHAL;
rxrpc_kernel_abort_call(afs_socket, call->rxcall,
abort_code, EBADMSG, "KUM");
goto do_abort;
}
}
done:
if (call->state == AFS_CALL_COMPLETE && call->incoming)
afs_put_call(call);
out:
_leave("");
return;
do_abort:
call->error = ret;
call->state = AFS_CALL_COMPLETE;
goto done;
}
/*
* wait synchronously for a call to complete
*/
static int afs_wait_for_call_to_complete(struct afs_call *call)
{
const char *abort_why;
int ret;
DECLARE_WAITQUEUE(myself, current);
_enter("");
add_wait_queue(&call->waitq, &myself);
for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
/* deliver any messages that are in the queue */
if (call->state < AFS_CALL_COMPLETE && call->need_attention) {
call->need_attention = false;
__set_current_state(TASK_RUNNING);
afs_deliver_to_call(call);
continue;
}
abort_why = "KWC";
ret = call->error;
if (call->state == AFS_CALL_COMPLETE)
break;
abort_why = "KWI";
ret = -EINTR;
if (signal_pending(current))
break;
schedule();
}
remove_wait_queue(&call->waitq, &myself);
__set_current_state(TASK_RUNNING);
/* kill the call */
if (call->state < AFS_CALL_COMPLETE) {
_debug("call incomplete");
rxrpc_kernel_abort_call(afs_socket, call->rxcall,
RX_CALL_DEAD, -ret, abort_why);
}
_debug("call complete");
afs_put_call(call);
_leave(" = %d", ret);
return ret;
}
/*
* wake up a waiting call
*/
static void afs_wake_up_call_waiter(struct sock *sk, struct rxrpc_call *rxcall,
unsigned long call_user_ID)
{
struct afs_call *call = (struct afs_call *)call_user_ID;
call->need_attention = true;
wake_up(&call->waitq);
}
/*
* wake up an asynchronous call
*/
static void afs_wake_up_async_call(struct sock *sk, struct rxrpc_call *rxcall,
unsigned long call_user_ID)
{
struct afs_call *call = (struct afs_call *)call_user_ID;
int u;
trace_afs_notify_call(rxcall, call);
call->need_attention = true;
u = __atomic_add_unless(&call->usage, 1, 0);
if (u != 0) {
trace_afs_call(call, afs_call_trace_wake, u,
atomic_read(&afs_outstanding_calls),
__builtin_return_address(0));
if (!queue_work(afs_async_calls, &call->async_work))
afs_put_call(call);
}
}
/*
* Delete an asynchronous call. The work item carries a ref to the call struct
* that we need to release.
*/
static void afs_delete_async_call(struct work_struct *work)
{
struct afs_call *call = container_of(work, struct afs_call, async_work);
_enter("");
afs_put_call(call);
_leave("");
}
/*
* Perform I/O processing on an asynchronous call. The work item carries a ref
* to the call struct that we either need to release or to pass on.
*/
static void afs_process_async_call(struct work_struct *work)
{
struct afs_call *call = container_of(work, struct afs_call, async_work);
_enter("");
if (call->state < AFS_CALL_COMPLETE && call->need_attention) {
call->need_attention = false;
afs_deliver_to_call(call);
}
if (call->state == AFS_CALL_COMPLETE) {
call->reply = NULL;
/* We have two refs to release - one from the alloc and one
* queued with the work item - and we can't just deallocate the
* call because the work item may be queued again.
*/
call->async_work.func = afs_delete_async_call;
if (!queue_work(afs_async_calls, &call->async_work))
afs_put_call(call);
}
afs_put_call(call);
_leave("");
}
static void afs_rx_attach(struct rxrpc_call *rxcall, unsigned long user_call_ID)
{
struct afs_call *call = (struct afs_call *)user_call_ID;
call->rxcall = rxcall;
}
/*
* Charge the incoming call preallocation.
*/
static void afs_charge_preallocation(struct work_struct *work)
{
struct afs_call *call = afs_spare_incoming_call;
for (;;) {
if (!call) {
call = afs_alloc_call(&afs_RXCMxxxx, GFP_KERNEL);
if (!call)
break;
call->async = true;
call->state = AFS_CALL_AWAIT_OP_ID;
init_waitqueue_head(&call->waitq);
}
if (rxrpc_kernel_charge_accept(afs_socket,
afs_wake_up_async_call,
afs_rx_attach,
(unsigned long)call,
GFP_KERNEL) < 0)
break;
call = NULL;
}
afs_spare_incoming_call = call;
}
/*
* Discard a preallocated call when a socket is shut down.
*/
static void afs_rx_discard_new_call(struct rxrpc_call *rxcall,
unsigned long user_call_ID)
{
struct afs_call *call = (struct afs_call *)user_call_ID;
call->rxcall = NULL;
afs_put_call(call);
}
/*
* Notification of an incoming call.
*/
static void afs_rx_new_call(struct sock *sk, struct rxrpc_call *rxcall,
unsigned long user_call_ID)
{
queue_work(afs_wq, &afs_charge_preallocation_work);
}
/*
* Grab the operation ID from an incoming cache manager call. The socket
* buffer is discarded on error or if we don't yet have sufficient data.
*/
static int afs_deliver_cm_op_id(struct afs_call *call)
{
int ret;
_enter("{%zu}", call->offset);
ASSERTCMP(call->offset, <, 4);
/* the operation ID forms the first four bytes of the request data */
ret = afs_extract_data(call, &call->tmp, 4, true);
if (ret < 0)
return ret;
call->operation_ID = ntohl(call->tmp);
call->state = AFS_CALL_AWAIT_REQUEST;
call->offset = 0;
/* ask the cache manager to route the call (it'll change the call type
* if successful) */
if (!afs_cm_incoming_call(call))
return -ENOTSUPP;
trace_afs_cb_call(call);
/* pass responsibility for the remainer of this message off to the
* cache manager op */
return call->type->deliver(call);
}
/*
* send an empty reply
*/
void afs_send_empty_reply(struct afs_call *call)
{
struct msghdr msg;
_enter("");
msg.msg_name = NULL;
msg.msg_namelen = 0;
iov_iter_kvec(&msg.msg_iter, WRITE | ITER_KVEC, NULL, 0, 0);
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_flags = 0;
call->state = AFS_CALL_AWAIT_ACK;
switch (rxrpc_kernel_send_data(afs_socket, call->rxcall, &msg, 0)) {
case 0:
_leave(" [replied]");
return;
case -ENOMEM:
_debug("oom");
rxrpc_kernel_abort_call(afs_socket, call->rxcall,
RX_USER_ABORT, ENOMEM, "KOO");
default:
_leave(" [error]");
return;
}
}
/*
* send a simple reply
*/
void afs_send_simple_reply(struct afs_call *call, const void *buf, size_t len)
{
struct msghdr msg;
struct kvec iov[1];
int n;
_enter("");
iov[0].iov_base = (void *) buf;
iov[0].iov_len = len;
msg.msg_name = NULL;
msg.msg_namelen = 0;
iov_iter_kvec(&msg.msg_iter, WRITE | ITER_KVEC, iov, 1, len);
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_flags = 0;
call->state = AFS_CALL_AWAIT_ACK;
n = rxrpc_kernel_send_data(afs_socket, call->rxcall, &msg, len);
if (n >= 0) {
/* Success */
_leave(" [replied]");
return;
}
if (n == -ENOMEM) {
_debug("oom");
rxrpc_kernel_abort_call(afs_socket, call->rxcall,
RX_USER_ABORT, ENOMEM, "KOO");
}
_leave(" [error]");
}
/*
* Extract a piece of data from the received data socket buffers.
*/
int afs_extract_data(struct afs_call *call, void *buf, size_t count,
bool want_more)
{
int ret;
_enter("{%s,%zu},,%zu,%d",
call->type->name, call->offset, count, want_more);
ASSERTCMP(call->offset, <=, count);
ret = rxrpc_kernel_recv_data(afs_socket, call->rxcall,
buf, count, &call->offset,
want_more, &call->abort_code);
trace_afs_recv_data(call, count, call->offset, want_more, ret);
if (ret == 0 || ret == -EAGAIN)
return ret;
if (ret == 1) {
switch (call->state) {
case AFS_CALL_AWAIT_REPLY:
call->state = AFS_CALL_COMPLETE;
break;
case AFS_CALL_AWAIT_REQUEST:
call->state = AFS_CALL_REPLYING;
break;
default:
break;
}
return 0;
}
if (ret == -ECONNABORTED)
call->error = call->type->abort_to_error(call->abort_code);
else
call->error = ret;
call->state = AFS_CALL_COMPLETE;
return ret;
}
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