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linux-next/fs/afs/vlclient.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 Volume Location Service client
*
* 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/gfp.h>
#include <linux/init.h>
#include <linux/sched.h>
#include "internal.h"
/*
* map volume locator abort codes to error codes
*/
static int afs_vl_abort_to_error(u32 abort_code)
{
_enter("%u", abort_code);
switch (abort_code) {
case AFSVL_IDEXIST: return -EEXIST;
case AFSVL_IO: return -EREMOTEIO;
case AFSVL_NAMEEXIST: return -EEXIST;
case AFSVL_CREATEFAIL: return -EREMOTEIO;
case AFSVL_NOENT: return -ENOMEDIUM;
case AFSVL_EMPTY: return -ENOMEDIUM;
case AFSVL_ENTDELETED: return -ENOMEDIUM;
case AFSVL_BADNAME: return -EINVAL;
case AFSVL_BADINDEX: return -EINVAL;
case AFSVL_BADVOLTYPE: return -EINVAL;
case AFSVL_BADSERVER: return -EINVAL;
case AFSVL_BADPARTITION: return -EINVAL;
case AFSVL_REPSFULL: return -EFBIG;
case AFSVL_NOREPSERVER: return -ENOENT;
case AFSVL_DUPREPSERVER: return -EEXIST;
case AFSVL_RWNOTFOUND: return -ENOENT;
case AFSVL_BADREFCOUNT: return -EINVAL;
case AFSVL_SIZEEXCEEDED: return -EINVAL;
case AFSVL_BADENTRY: return -EINVAL;
case AFSVL_BADVOLIDBUMP: return -EINVAL;
case AFSVL_IDALREADYHASHED: return -EINVAL;
case AFSVL_ENTRYLOCKED: return -EBUSY;
case AFSVL_BADVOLOPER: return -EBADRQC;
case AFSVL_BADRELLOCKTYPE: return -EINVAL;
case AFSVL_RERELEASE: return -EREMOTEIO;
case AFSVL_BADSERVERFLAG: return -EINVAL;
case AFSVL_PERM: return -EACCES;
case AFSVL_NOMEM: return -EREMOTEIO;
default:
return afs_abort_to_error(abort_code);
}
}
/*
* deliver reply data to a VL.GetEntryByXXX call
*/
static int afs_deliver_vl_get_entry_by_xxx(struct afs_call *call)
{
struct afs_cache_vlocation *entry;
__be32 *bp;
u32 tmp;
int loop, ret;
_enter("");
ret = afs_transfer_reply(call);
if (ret < 0)
return ret;
/* unmarshall the reply once we've received all of it */
entry = call->reply;
bp = call->buffer;
for (loop = 0; loop < 64; loop++)
entry->name[loop] = ntohl(*bp++);
entry->name[loop] = 0;
bp++; /* final NUL */
bp++; /* type */
entry->nservers = ntohl(*bp++);
for (loop = 0; loop < 8; loop++)
entry->servers[loop].s_addr = *bp++;
bp += 8; /* partition IDs */
for (loop = 0; loop < 8; loop++) {
tmp = ntohl(*bp++);
entry->srvtmask[loop] = 0;
if (tmp & AFS_VLSF_RWVOL)
entry->srvtmask[loop] |= AFS_VOL_VTM_RW;
if (tmp & AFS_VLSF_ROVOL)
entry->srvtmask[loop] |= AFS_VOL_VTM_RO;
if (tmp & AFS_VLSF_BACKVOL)
entry->srvtmask[loop] |= AFS_VOL_VTM_BAK;
}
entry->vid[0] = ntohl(*bp++);
entry->vid[1] = ntohl(*bp++);
entry->vid[2] = ntohl(*bp++);
bp++; /* clone ID */
tmp = ntohl(*bp++); /* flags */
entry->vidmask = 0;
if (tmp & AFS_VLF_RWEXISTS)
entry->vidmask |= AFS_VOL_VTM_RW;
if (tmp & AFS_VLF_ROEXISTS)
entry->vidmask |= AFS_VOL_VTM_RO;
if (tmp & AFS_VLF_BACKEXISTS)
entry->vidmask |= AFS_VOL_VTM_BAK;
if (!entry->vidmask)
return -EBADMSG;
_leave(" = 0 [done]");
return 0;
}
/*
* VL.GetEntryByName operation type
*/
static const struct afs_call_type afs_RXVLGetEntryByName = {
.name = "VL.GetEntryByName",
.deliver = afs_deliver_vl_get_entry_by_xxx,
.abort_to_error = afs_vl_abort_to_error,
.destructor = afs_flat_call_destructor,
};
/*
* VL.GetEntryById operation type
*/
static const struct afs_call_type afs_RXVLGetEntryById = {
.name = "VL.GetEntryById",
.deliver = afs_deliver_vl_get_entry_by_xxx,
.abort_to_error = afs_vl_abort_to_error,
.destructor = afs_flat_call_destructor,
};
/*
* dispatch a get volume entry by name operation
*/
int afs_vl_get_entry_by_name(struct in_addr *addr,
struct key *key,
const char *volname,
struct afs_cache_vlocation *entry,
const struct afs_wait_mode *wait_mode)
{
struct afs_call *call;
size_t volnamesz, reqsz, padsz;
__be32 *bp;
_enter("");
volnamesz = strlen(volname);
padsz = (4 - (volnamesz & 3)) & 3;
reqsz = 8 + volnamesz + padsz;
call = afs_alloc_flat_call(&afs_RXVLGetEntryByName, reqsz, 384);
if (!call)
return -ENOMEM;
call->key = key;
call->reply = entry;
call->service_id = VL_SERVICE;
call->port = htons(AFS_VL_PORT);
/* marshall the parameters */
bp = call->request;
*bp++ = htonl(VLGETENTRYBYNAME);
*bp++ = htonl(volnamesz);
memcpy(bp, volname, volnamesz);
if (padsz > 0)
memset((void *) bp + volnamesz, 0, padsz);
/* initiate the call */
return afs_make_call(addr, call, GFP_KERNEL, wait_mode);
}
/*
* dispatch a get volume entry by ID operation
*/
int afs_vl_get_entry_by_id(struct in_addr *addr,
struct key *key,
afs_volid_t volid,
afs_voltype_t voltype,
struct afs_cache_vlocation *entry,
const struct afs_wait_mode *wait_mode)
{
struct afs_call *call;
__be32 *bp;
_enter("");
call = afs_alloc_flat_call(&afs_RXVLGetEntryById, 12, 384);
if (!call)
return -ENOMEM;
call->key = key;
call->reply = entry;
call->service_id = VL_SERVICE;
call->port = htons(AFS_VL_PORT);
/* marshall the parameters */
bp = call->request;
*bp++ = htonl(VLGETENTRYBYID);
*bp++ = htonl(volid);
*bp = htonl(voltype);
/* initiate the call */
return afs_make_call(addr, call, GFP_KERNEL, wait_mode);
}
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