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linux/fs/afs/cmservice.c
David Howells 98bf40cd99 afs: Protect call->state changes against signals 
Protect call->state changes against the call being prematurely terminated
due to a signal.

What can happen is that a signal causes afs_wait_for_call_to_complete() to
abort an afs_call because it's not yet complete whilst afs_deliver_to_call()
is delivering data to that call.

If the data delivery causes the state to change, this may overwrite the state
of the afs_call, making it not-yet-complete again - but no further
notifications will be forthcoming from AF_RXRPC as the rxrpc call has been
aborted and completed, so kAFS will just hang in various places waiting for
that call or on page bits that need clearing by that call.

A tracepoint to monitor call state changes is also provided.

Signed-off-by: David Howells <dhowells@redhat.com>
2017-11-13 15:38:21 +00:00

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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 *);
static void SRXAFSCB_CallBack(struct work_struct *);
static void SRXAFSCB_InitCallBackState(struct work_struct *);
static void SRXAFSCB_Probe(struct work_struct *);
static void SRXAFSCB_ProbeUuid(struct work_struct *);
static void SRXAFSCB_TellMeAboutYourself(struct work_struct *);
#define CM_NAME(name) \
const char afs_SRXCB##name##_name[] __tracepoint_string = \
"CB." #name
/*
* CB.CallBack operation type
*/
static CM_NAME(CallBack);
static const struct afs_call_type afs_SRXCBCallBack = {
.name = afs_SRXCBCallBack_name,
.deliver = afs_deliver_cb_callback,
.destructor = afs_cm_destructor,
.work = SRXAFSCB_CallBack,
};
/*
* CB.InitCallBackState operation type
*/
static CM_NAME(InitCallBackState);
static const struct afs_call_type afs_SRXCBInitCallBackState = {
.name = afs_SRXCBInitCallBackState_name,
.deliver = afs_deliver_cb_init_call_back_state,
.destructor = afs_cm_destructor,
.work = SRXAFSCB_InitCallBackState,
};
/*
* CB.InitCallBackState3 operation type
*/
static CM_NAME(InitCallBackState3);
static const struct afs_call_type afs_SRXCBInitCallBackState3 = {
.name = afs_SRXCBInitCallBackState3_name,
.deliver = afs_deliver_cb_init_call_back_state3,
.destructor = afs_cm_destructor,
.work = SRXAFSCB_InitCallBackState,
};
/*
* CB.Probe operation type
*/
static CM_NAME(Probe);
static const struct afs_call_type afs_SRXCBProbe = {
.name = afs_SRXCBProbe_name,
.deliver = afs_deliver_cb_probe,
.destructor = afs_cm_destructor,
.work = SRXAFSCB_Probe,
};
/*
* CB.ProbeUuid operation type
*/
static CM_NAME(ProbeUuid);
static const struct afs_call_type afs_SRXCBProbeUuid = {
.name = afs_SRXCBProbeUuid_name,
.deliver = afs_deliver_cb_probe_uuid,
.destructor = afs_cm_destructor,
.work = SRXAFSCB_ProbeUuid,
};
/*
* CB.TellMeAboutYourself operation type
*/
static CM_NAME(TellMeAboutYourself);
static const struct afs_call_type afs_SRXCBTellMeAboutYourself = {
.name = afs_SRXCBTellMeAboutYourself_name,
.deliver = afs_deliver_cb_tell_me_about_yourself,
.destructor = afs_cm_destructor,
.work = SRXAFSCB_TellMeAboutYourself,
};
/*
* route an incoming cache manager call
* - return T if supported, F if not
*/
bool afs_cm_incoming_call(struct afs_call *call)
{
_enter("{CB.OP %u}", call->operation_ID);
switch (call->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 CBProbeUuid:
call->type = &afs_SRXCBProbeUuid;
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->cm_server && call->count && call->request);
afs_break_callbacks(call->cm_server, call->count, call->request);
}
kfree(call->buffer);
call->buffer = NULL;
}
/*
* The server supplied a list of callbacks that it wanted to break.
*/
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->cm_server, call->count, call->request);
afs_put_call(call);
_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;
int ret, loop;
_enter("{%u}", call->unmarshall);
switch (call->unmarshall) {
case 0:
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;
call->count2 = ntohl(call->tmp);
_debug("CB count: %u", call->count2);
if (call->count2 != call->count && call->count2 != 0)
return -EBADMSG;
call->offset = 0;
call->unmarshall++;
case 4:
_debug("extract CB array");
ret = afs_extract_data(call, call->buffer,
call->count2 * 3 * 4, false);
if (ret < 0)
return ret;
_debug("unmarshall CB array");
cb = call->request;
bp = call->buffer;
for (loop = call->count2; 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;
}
if (!afs_check_call_state(call, AFS_CALL_SV_REPLYING))
return -EIO;
/* we'll need the file server record as that tells us which set of
* vnodes to operate upon */
rxrpc_kernel_get_peer(call->net->socket, call->rxcall, &srx);
server = afs_find_server(call->net, &srx);
if (!server)
return -ENOTCONN;
call->cm_server = server;
return afs_queue_call_work(call);
}
/*
* 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->cm_server);
afs_init_callback_state(call->cm_server);
afs_send_empty_reply(call);
afs_put_call(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(call->net->socket, call->rxcall, &srx);
ret = afs_extract_data(call, NULL, 0, false);
if (ret < 0)
return ret;
/* we'll need the file server record as that tells us which set of
* vnodes to operate upon */
server = afs_find_server(call->net, &srx);
if (!server)
return -ENOTCONN;
call->cm_server = server;
return afs_queue_call_work(call);
}
/*
* 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("");
_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 = b[0];
r->time_mid = htons(ntohl(b[1]));
r->time_hi_and_version = htons(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;
}
if (!afs_check_call_state(call, AFS_CALL_SV_REPLYING))
return -EIO;
/* we'll need the file server record as that tells us which set of
* vnodes to operate upon */
rxrpc_kernel_get_peer(call->net->socket, call->rxcall, &srx);
server = afs_find_server(call->net, &srx);
if (!server)
return -ENOTCONN;
call->cm_server = server;
return afs_queue_call_work(call);
}
/*
* 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);
afs_put_call(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;
if (!afs_check_call_state(call, AFS_CALL_SV_REPLYING))
return -EIO;
return afs_queue_call_work(call);
}
/*
* 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, &call->net->uuid, sizeof(call->net->uuid)) == 0)
reply.match = htonl(0);
else
reply.match = htonl(1);
afs_send_simple_reply(call, &reply, sizeof(reply));
afs_put_call(call);
_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;
}
if (!afs_check_call_state(call, AFS_CALL_SV_REPLYING))
return -EIO;
return afs_queue_call_work(call);
}
/*
* 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] = call->net->uuid.time_low;
reply.ia.uuid[1] = htonl(ntohs(call->net->uuid.time_mid));
reply.ia.uuid[2] = htonl(ntohs(call->net->uuid.time_hi_and_version));
reply.ia.uuid[3] = htonl((s8) call->net->uuid.clock_seq_hi_and_reserved);
reply.ia.uuid[4] = htonl((s8) call->net->uuid.clock_seq_low);
for (loop = 0; loop < 6; loop++)
reply.ia.uuid[loop + 5] = htonl((s8) call->net->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));
afs_put_call(call);
_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;
if (!afs_check_call_state(call, AFS_CALL_SV_REPLYING))
return -EIO;
return afs_queue_call_work(call);
}
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