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linux-next/fs/afs/cmservice.c
David Howells d001648ec7 rxrpc: Don't expose skbs to in-kernel users [ver #2] 
Don't expose skbs to in-kernel users, such as the AFS filesystem, but
instead provide a notification hook the indicates that a call needs
attention and another that indicates that there's a new call to be
collected.

This makes the following possibilities more achievable:

 (1) Call refcounting can be made simpler if skbs don't hold refs to calls.

 (2) skbs referring to non-data events will be able to be freed much sooner
     rather than being queued for AFS to pick up as rxrpc_kernel_recv_data
     will be able to consult the call state.

 (3) We can shortcut the receive phase when a call is remotely aborted
     because we don't have to go through all the packets to get to the one
     cancelling the operation.

 (4) It makes it easier to do encryption/decryption directly between AFS's
     buffers and sk_buffs.

 (5) Encryption/decryption can more easily be done in the AFS's thread
     contexts - usually that of the userspace process that issued a syscall
     - rather than in one of rxrpc's background threads on a workqueue.

 (6) AFS will be able to wait synchronously on a call inside AF_RXRPC.

To make this work, the following interface function has been added:

     int rxrpc_kernel_recv_data(
		struct socket *sock, struct rxrpc_call *call,
		void *buffer, size_t bufsize, size_t *_offset,
		bool want_more, u32 *_abort_code);

This is the recvmsg equivalent.  It allows the caller to find out about the
state of a specific call and to transfer received data into a buffer
piecemeal.

afs_extract_data() and rxrpc_kernel_recv_data() now do all the extraction
logic between them.  They don't wait synchronously yet because the socket
lock needs to be dealt with.

Five interface functions have been removed:

	rxrpc_kernel_is_data_last()
    	rxrpc_kernel_get_abort_code()
    	rxrpc_kernel_get_error_number()
    	rxrpc_kernel_free_skb()
    	rxrpc_kernel_data_consumed()

As a temporary hack, sk_buffs going to an in-kernel call are queued on the
rxrpc_call struct (->knlrecv_queue) rather than being handed over to the
in-kernel user.  To process the queue internally, a temporary function,
temp_deliver_data() has been added.  This will be replaced with common code
between the rxrpc_recvmsg() path and the kernel_rxrpc_recv_data() path in a
future patch.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-01 16:43:27 -07:00

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/* AFS Cache Manager Service
*
* Copyright (C) 2002 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/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/ip.h>
#include "internal.h"
#include "afs_cm.h"
static int afs_deliver_cb_init_call_back_state(struct afs_call *);
static int afs_deliver_cb_init_call_back_state3(struct afs_call *);
static int afs_deliver_cb_probe(struct afs_call *);
static int afs_deliver_cb_callback(struct afs_call *);
static int afs_deliver_cb_probe_uuid(struct afs_call *);
static int afs_deliver_cb_tell_me_about_yourself(struct afs_call *);
static void afs_cm_destructor(struct afs_call *);
/*
* CB.CallBack operation type
*/
static const struct afs_call_type afs_SRXCBCallBack = {
.name = "CB.CallBack",
.deliver = afs_deliver_cb_callback,
.abort_to_error = afs_abort_to_error,
.destructor = afs_cm_destructor,
};
/*
* CB.InitCallBackState operation type
*/
static const struct afs_call_type afs_SRXCBInitCallBackState = {
.name = "CB.InitCallBackState",
.deliver = afs_deliver_cb_init_call_back_state,
.abort_to_error = afs_abort_to_error,
.destructor = afs_cm_destructor,
};
/*
* CB.InitCallBackState3 operation type
*/
static const struct afs_call_type afs_SRXCBInitCallBackState3 = {
.name = "CB.InitCallBackState3",
.deliver = afs_deliver_cb_init_call_back_state3,
.abort_to_error = afs_abort_to_error,
.destructor = afs_cm_destructor,
};
/*
* CB.Probe operation type
*/
static const struct afs_call_type afs_SRXCBProbe = {
.name = "CB.Probe",
.deliver = afs_deliver_cb_probe,
.abort_to_error = afs_abort_to_error,
.destructor = afs_cm_destructor,
};
/*
* CB.ProbeUuid operation type
*/
static const struct afs_call_type afs_SRXCBProbeUuid = {
.name = "CB.ProbeUuid",
.deliver = afs_deliver_cb_probe_uuid,
.abort_to_error = afs_abort_to_error,
.destructor = afs_cm_destructor,
};
/*
* CB.TellMeAboutYourself operation type
*/
static const struct afs_call_type afs_SRXCBTellMeAboutYourself = {
.name = "CB.TellMeAboutYourself",
.deliver = afs_deliver_cb_tell_me_about_yourself,
.abort_to_error = afs_abort_to_error,
.destructor = afs_cm_destructor,
};
/*
* route an incoming cache manager call
* - return T if supported, F if not
*/
bool afs_cm_incoming_call(struct afs_call *call)
{
u32 operation_id = ntohl(call->operation_ID);
_enter("{CB.OP %u}", operation_id);
switch (operation_id) {
case CBCallBack:
call->type = &afs_SRXCBCallBack;
return true;
case CBInitCallBackState:
call->type = &afs_SRXCBInitCallBackState;
return true;
case CBInitCallBackState3:
call->type = &afs_SRXCBInitCallBackState3;
return true;
case CBProbe:
call->type = &afs_SRXCBProbe;
return true;
case CBTellMeAboutYourself:
call->type = &afs_SRXCBTellMeAboutYourself;
return true;
default:
return false;
}
}
/*
* clean up a cache manager call
*/
static void afs_cm_destructor(struct afs_call *call)
{
_enter("");
/* Break the callbacks here so that we do it after the final ACK is
* received. The step number here must match the final number in
* afs_deliver_cb_callback().
*/
if (call->unmarshall == 5) {
ASSERT(call->server && call->count && call->request);
afs_break_callbacks(call->server, call->count, call->request);
}
afs_put_server(call->server);
call->server = NULL;
kfree(call->buffer);
call->buffer = NULL;
}
/*
* allow the fileserver to see if the cache manager is still alive
*/
static void SRXAFSCB_CallBack(struct work_struct *work)
{
struct afs_call *call = container_of(work, struct afs_call, work);
_enter("");
/* be sure to send the reply *before* attempting to spam the AFS server
* with FSFetchStatus requests on the vnodes with broken callbacks lest
* the AFS server get into a vicious cycle of trying to break further
* callbacks because it hadn't received completion of the CBCallBack op
* yet */
afs_send_empty_reply(call);
afs_break_callbacks(call->server, call->count, call->request);
_leave("");
}
/*
* deliver request data to a CB.CallBack call
*/
static int afs_deliver_cb_callback(struct afs_call *call)
{
struct sockaddr_rxrpc srx;
struct afs_callback *cb;
struct afs_server *server;
__be32 *bp;
u32 tmp;
int ret, loop;
_enter("{%u}", call->unmarshall);
switch (call->unmarshall) {
case 0:
rxrpc_kernel_get_peer(afs_socket, call->rxcall, &srx);
call->offset = 0;
call->unmarshall++;
/* extract the FID array and its count in two steps */
case 1:
_debug("extract FID count");
ret = afs_extract_data(call, &call->tmp, 4, true);
if (ret < 0)
return ret;
call->count = ntohl(call->tmp);
_debug("FID count: %u", call->count);
if (call->count > AFSCBMAX)
return -EBADMSG;
call->buffer = kmalloc(call->count * 3 * 4, GFP_KERNEL);
if (!call->buffer)
return -ENOMEM;
call->offset = 0;
call->unmarshall++;
case 2:
_debug("extract FID array");
ret = afs_extract_data(call, call->buffer,
call->count * 3 * 4, true);
if (ret < 0)
return ret;
_debug("unmarshall FID array");
call->request = kcalloc(call->count,
sizeof(struct afs_callback),
GFP_KERNEL);
if (!call->request)
return -ENOMEM;
cb = call->request;
bp = call->buffer;
for (loop = call->count; loop > 0; loop--, cb++) {
cb->fid.vid = ntohl(*bp++);
cb->fid.vnode = ntohl(*bp++);
cb->fid.unique = ntohl(*bp++);
cb->type = AFSCM_CB_UNTYPED;
}
call->offset = 0;
call->unmarshall++;
/* extract the callback array and its count in two steps */
case 3:
_debug("extract CB count");
ret = afs_extract_data(call, &call->tmp, 4, true);
if (ret < 0)
return ret;
tmp = ntohl(call->tmp);
_debug("CB count: %u", tmp);
if (tmp != call->count && tmp != 0)
return -EBADMSG;
call->offset = 0;
call->unmarshall++;
case 4:
_debug("extract CB array");
ret = afs_extract_data(call, call->buffer,
call->count * 3 * 4, false);
if (ret < 0)
return ret;
_debug("unmarshall CB array");
cb = call->request;
bp = call->buffer;
for (loop = call->count; loop > 0; loop--, cb++) {
cb->version = ntohl(*bp++);
cb->expiry = ntohl(*bp++);
cb->type = ntohl(*bp++);
}
call->offset = 0;
call->unmarshall++;
/* Record that the message was unmarshalled successfully so
* that the call destructor can know do the callback breaking
* work, even if the final ACK isn't received.
*
* If the step number changes, then afs_cm_destructor() must be
* updated also.
*/
call->unmarshall++;
case 5:
break;
}
call->state = AFS_CALL_REPLYING;
/* we'll need the file server record as that tells us which set of
* vnodes to operate upon */
server = afs_find_server(&srx);
if (!server)
return -ENOTCONN;
call->server = server;
INIT_WORK(&call->work, SRXAFSCB_CallBack);
queue_work(afs_wq, &call->work);
return 0;
}
/*
* allow the fileserver to request callback state (re-)initialisation
*/
static void SRXAFSCB_InitCallBackState(struct work_struct *work)
{
struct afs_call *call = container_of(work, struct afs_call, work);
_enter("{%p}", call->server);
afs_init_callback_state(call->server);
afs_send_empty_reply(call);
_leave("");
}
/*
* deliver request data to a CB.InitCallBackState call
*/
static int afs_deliver_cb_init_call_back_state(struct afs_call *call)
{
struct sockaddr_rxrpc srx;
struct afs_server *server;
int ret;
_enter("");
rxrpc_kernel_get_peer(afs_socket, call->rxcall, &srx);
ret = afs_extract_data(call, NULL, 0, false);
if (ret < 0)
return ret;
/* no unmarshalling required */
call->state = AFS_CALL_REPLYING;
/* we'll need the file server record as that tells us which set of
* vnodes to operate upon */
server = afs_find_server(&srx);
if (!server)
return -ENOTCONN;
call->server = server;
INIT_WORK(&call->work, SRXAFSCB_InitCallBackState);
queue_work(afs_wq, &call->work);
return 0;
}
/*
* deliver request data to a CB.InitCallBackState3 call
*/
static int afs_deliver_cb_init_call_back_state3(struct afs_call *call)
{
struct sockaddr_rxrpc srx;
struct afs_server *server;
struct afs_uuid *r;
unsigned loop;
__be32 *b;
int ret;
_enter("");
rxrpc_kernel_get_peer(afs_socket, call->rxcall, &srx);
_enter("{%u}", call->unmarshall);
switch (call->unmarshall) {
case 0:
call->offset = 0;
call->buffer = kmalloc(11 * sizeof(__be32), GFP_KERNEL);
if (!call->buffer)
return -ENOMEM;
call->unmarshall++;
case 1:
_debug("extract UUID");
ret = afs_extract_data(call, call->buffer,
11 * sizeof(__be32), false);
switch (ret) {
case 0: break;
case -EAGAIN: return 0;
default: return ret;
}
_debug("unmarshall UUID");
call->request = kmalloc(sizeof(struct afs_uuid), GFP_KERNEL);
if (!call->request)
return -ENOMEM;
b = call->buffer;
r = call->request;
r->time_low = ntohl(b[0]);
r->time_mid = ntohl(b[1]);
r->time_hi_and_version = ntohl(b[2]);
r->clock_seq_hi_and_reserved = ntohl(b[3]);
r->clock_seq_low = ntohl(b[4]);
for (loop = 0; loop < 6; loop++)
r->node[loop] = ntohl(b[loop + 5]);
call->offset = 0;
call->unmarshall++;
case 2:
break;
}
/* no unmarshalling required */
call->state = AFS_CALL_REPLYING;
/* we'll need the file server record as that tells us which set of
* vnodes to operate upon */
server = afs_find_server(&srx);
if (!server)
return -ENOTCONN;
call->server = server;
INIT_WORK(&call->work, SRXAFSCB_InitCallBackState);
queue_work(afs_wq, &call->work);
return 0;
}
/*
* allow the fileserver to see if the cache manager is still alive
*/
static void SRXAFSCB_Probe(struct work_struct *work)
{
struct afs_call *call = container_of(work, struct afs_call, work);
_enter("");
afs_send_empty_reply(call);
_leave("");
}
/*
* deliver request data to a CB.Probe call
*/
static int afs_deliver_cb_probe(struct afs_call *call)
{
int ret;
_enter("");
ret = afs_extract_data(call, NULL, 0, false);
if (ret < 0)
return ret;
/* no unmarshalling required */
call->state = AFS_CALL_REPLYING;
INIT_WORK(&call->work, SRXAFSCB_Probe);
queue_work(afs_wq, &call->work);
return 0;
}
/*
* allow the fileserver to quickly find out if the fileserver has been rebooted
*/
static void SRXAFSCB_ProbeUuid(struct work_struct *work)
{
struct afs_call *call = container_of(work, struct afs_call, work);
struct afs_uuid *r = call->request;
struct {
__be32 match;
} reply;
_enter("");
if (memcmp(r, &afs_uuid, sizeof(afs_uuid)) == 0)
reply.match = htonl(0);
else
reply.match = htonl(1);
afs_send_simple_reply(call, &reply, sizeof(reply));
_leave("");
}
/*
* deliver request data to a CB.ProbeUuid call
*/
static int afs_deliver_cb_probe_uuid(struct afs_call *call)
{
struct afs_uuid *r;
unsigned loop;
__be32 *b;
int ret;
_enter("{%u}", call->unmarshall);
switch (call->unmarshall) {
case 0:
call->offset = 0;
call->buffer = kmalloc(11 * sizeof(__be32), GFP_KERNEL);
if (!call->buffer)
return -ENOMEM;
call->unmarshall++;
case 1:
_debug("extract UUID");
ret = afs_extract_data(call, call->buffer,
11 * sizeof(__be32), false);
switch (ret) {
case 0: break;
case -EAGAIN: return 0;
default: return ret;
}
_debug("unmarshall UUID");
call->request = kmalloc(sizeof(struct afs_uuid), GFP_KERNEL);
if (!call->request)
return -ENOMEM;
b = call->buffer;
r = call->request;
r->time_low = ntohl(b[0]);
r->time_mid = ntohl(b[1]);
r->time_hi_and_version = ntohl(b[2]);
r->clock_seq_hi_and_reserved = ntohl(b[3]);
r->clock_seq_low = ntohl(b[4]);
for (loop = 0; loop < 6; loop++)
r->node[loop] = ntohl(b[loop + 5]);
call->offset = 0;
call->unmarshall++;
case 2:
break;
}
call->state = AFS_CALL_REPLYING;
INIT_WORK(&call->work, SRXAFSCB_ProbeUuid);
queue_work(afs_wq, &call->work);
return 0;
}
/*
* allow the fileserver to ask about the cache manager's capabilities
*/
static void SRXAFSCB_TellMeAboutYourself(struct work_struct *work)
{
struct afs_interface *ifs;
struct afs_call *call = container_of(work, struct afs_call, work);
int loop, nifs;
struct {
struct /* InterfaceAddr */ {
__be32 nifs;
__be32 uuid[11];
__be32 ifaddr[32];
__be32 netmask[32];
__be32 mtu[32];
} ia;
struct /* Capabilities */ {
__be32 capcount;
__be32 caps[1];
} cap;
} reply;
_enter("");
nifs = 0;
ifs = kcalloc(32, sizeof(*ifs), GFP_KERNEL);
if (ifs) {
nifs = afs_get_ipv4_interfaces(ifs, 32, false);
if (nifs < 0) {
kfree(ifs);
ifs = NULL;
nifs = 0;
}
}
memset(&reply, 0, sizeof(reply));
reply.ia.nifs = htonl(nifs);
reply.ia.uuid[0] = htonl(afs_uuid.time_low);
reply.ia.uuid[1] = htonl(afs_uuid.time_mid);
reply.ia.uuid[2] = htonl(afs_uuid.time_hi_and_version);
reply.ia.uuid[3] = htonl((s8) afs_uuid.clock_seq_hi_and_reserved);
reply.ia.uuid[4] = htonl((s8) afs_uuid.clock_seq_low);
for (loop = 0; loop < 6; loop++)
reply.ia.uuid[loop + 5] = htonl((s8) afs_uuid.node[loop]);
if (ifs) {
for (loop = 0; loop < nifs; loop++) {
reply.ia.ifaddr[loop] = ifs[loop].address.s_addr;
reply.ia.netmask[loop] = ifs[loop].netmask.s_addr;
reply.ia.mtu[loop] = htonl(ifs[loop].mtu);
}
kfree(ifs);
}
reply.cap.capcount = htonl(1);
reply.cap.caps[0] = htonl(AFS_CAP_ERROR_TRANSLATION);
afs_send_simple_reply(call, &reply, sizeof(reply));
_leave("");
}
/*
* deliver request data to a CB.TellMeAboutYourself call
*/
static int afs_deliver_cb_tell_me_about_yourself(struct afs_call *call)
{
int ret;
_enter("");
ret = afs_extract_data(call, NULL, 0, false);
if (ret < 0)
return ret;
/* no unmarshalling required */
call->state = AFS_CALL_REPLYING;
INIT_WORK(&call->work, SRXAFSCB_TellMeAboutYourself);
queue_work(afs_wq, &call->work);
return 0;
}
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