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rxrpc: Don't expose skbs to in-kernel users [ver #2]

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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>
This commit is contained in:
David Howells
2016-08-30 20:42:14 +01:00
committed by David S. Miller
parent 95ac399451
commit d001648ec7
16 changed files with 566 additions and 587 deletions
Download Patch File Download Diff File Expand all files Collapse all files

142
fs/afs/cmservice.c
View File

@@ -17,15 +17,12 @@
#include "internal.h"
#include "afs_cm.h"
static int afs_deliver_cb_init_call_back_state(struct afs_call *,
struct sk_buff *, bool);
static int afs_deliver_cb_init_call_back_state3(struct afs_call *,
struct sk_buff *, bool);
static int afs_deliver_cb_probe(struct afs_call *, struct sk_buff *, bool);
static int afs_deliver_cb_callback(struct afs_call *, struct sk_buff *, bool);
static int afs_deliver_cb_probe_uuid(struct afs_call *, struct sk_buff *, bool);
static int afs_deliver_cb_tell_me_about_yourself(struct afs_call *,
struct sk_buff *, bool);
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 *);
/*
@@ -130,7 +127,7 @@ static void afs_cm_destructor(struct afs_call *call)
* received. The step number here must match the final number in
* afs_deliver_cb_callback().
*/
if (call->unmarshall == 6) {
if (call->unmarshall == 5) {
ASSERT(call->server && call->count && call->request);
afs_break_callbacks(call->server, call->count, call->request);
}
@@ -164,8 +161,7 @@ static void SRXAFSCB_CallBack(struct work_struct *work)
/*
* deliver request data to a CB.CallBack call
*/
static int afs_deliver_cb_callback(struct afs_call *call, struct sk_buff *skb,
bool last)
static int afs_deliver_cb_callback(struct afs_call *call)
{
struct sockaddr_rxrpc srx;
struct afs_callback *cb;
@@ -174,7 +170,7 @@ static int afs_deliver_cb_callback(struct afs_call *call, struct sk_buff *skb,
u32 tmp;
int ret, loop;
_enter("{%u},{%u},%d", call->unmarshall, skb->len, last);
_enter("{%u}", call->unmarshall);
switch (call->unmarshall) {
case 0:
@@ -185,7 +181,7 @@ static int afs_deliver_cb_callback(struct afs_call *call, struct sk_buff *skb,
/* extract the FID array and its count in two steps */
case 1:
_debug("extract FID count");
ret = afs_extract_data(call, skb, last, &call->tmp, 4);
ret = afs_extract_data(call, &call->tmp, 4, true);
if (ret < 0)
return ret;
@@ -202,8 +198,8 @@ static int afs_deliver_cb_callback(struct afs_call *call, struct sk_buff *skb,
case 2:
_debug("extract FID array");
ret = afs_extract_data(call, skb, last, call->buffer,
call->count * 3 * 4);
ret = afs_extract_data(call, call->buffer,
call->count * 3 * 4, true);
if (ret < 0)
return ret;
@@ -229,7 +225,7 @@ static int afs_deliver_cb_callback(struct afs_call *call, struct sk_buff *skb,
/* extract the callback array and its count in two steps */
case 3:
_debug("extract CB count");
ret = afs_extract_data(call, skb, last, &call->tmp, 4);
ret = afs_extract_data(call, &call->tmp, 4, true);
if (ret < 0)
return ret;
@@ -239,13 +235,11 @@ static int afs_deliver_cb_callback(struct afs_call *call, struct sk_buff *skb,
return -EBADMSG;
call->offset = 0;
call->unmarshall++;
if (tmp == 0)
goto empty_cb_array;
case 4:
_debug("extract CB array");
ret = afs_extract_data(call, skb, last, call->request,
call->count * 3 * 4);
ret = afs_extract_data(call, call->buffer,
call->count * 3 * 4, false);
if (ret < 0)
return ret;
@@ -258,15 +252,9 @@ static int afs_deliver_cb_callback(struct afs_call *call, struct sk_buff *skb,
cb->type = ntohl(*bp++);
}
empty_cb_array:
call->offset = 0;
call->unmarshall++;
case 5:
ret = afs_data_complete(call, skb, last);
if (ret < 0)
return ret;
/* 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.
@@ -275,7 +263,7 @@ static int afs_deliver_cb_callback(struct afs_call *call, struct sk_buff *skb,
* updated also.
*/
call->unmarshall++;
case 6:
case 5:
break;
}
@@ -310,19 +298,17 @@ static void SRXAFSCB_InitCallBackState(struct work_struct *work)
/*
* deliver request data to a CB.InitCallBackState call
*/
static int afs_deliver_cb_init_call_back_state(struct afs_call *call,
struct sk_buff *skb,
bool last)
static int afs_deliver_cb_init_call_back_state(struct afs_call *call)
{
struct sockaddr_rxrpc srx;
struct afs_server *server;
int ret;
_enter(",{%u},%d", skb->len, last);
_enter("");
rxrpc_kernel_get_peer(afs_socket, call->rxcall, &srx);
ret = afs_data_complete(call, skb, last);
ret = afs_extract_data(call, NULL, 0, false);
if (ret < 0)
return ret;
@@ -344,21 +330,61 @@ static int afs_deliver_cb_init_call_back_state(struct afs_call *call,
/*
* deliver request data to a CB.InitCallBackState3 call
*/
static int afs_deliver_cb_init_call_back_state3(struct afs_call *call,
struct sk_buff *skb,
bool last)
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(",{%u},%d", skb->len, last);
_enter("");
rxrpc_kernel_get_peer(afs_socket, call->rxcall, &srx);
/* There are some arguments that we ignore */
afs_data_consumed(call, skb);
if (!last)
return -EAGAIN;
_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;
@@ -390,14 +416,13 @@ static void SRXAFSCB_Probe(struct work_struct *work)
/*
* deliver request data to a CB.Probe call
*/
static int afs_deliver_cb_probe(struct afs_call *call, struct sk_buff *skb,
bool last)
static int afs_deliver_cb_probe(struct afs_call *call)
{
int ret;
_enter(",{%u},%d", skb->len, last);
_enter("");
ret = afs_data_complete(call, skb, last);
ret = afs_extract_data(call, NULL, 0, false);
if (ret < 0)
return ret;
@@ -435,19 +460,14 @@ static void SRXAFSCB_ProbeUuid(struct work_struct *work)
/*
* deliver request data to a CB.ProbeUuid call
*/
static int afs_deliver_cb_probe_uuid(struct afs_call *call, struct sk_buff *skb,
bool last)
static int afs_deliver_cb_probe_uuid(struct afs_call *call)
{
struct afs_uuid *r;
unsigned loop;
__be32 *b;
int ret;
_enter("{%u},{%u},%d", call->unmarshall, skb->len, last);
ret = afs_data_complete(call, skb, last);
if (ret < 0)
return ret;
_enter("{%u}", call->unmarshall);
switch (call->unmarshall) {
case 0:
@@ -459,8 +479,8 @@ static int afs_deliver_cb_probe_uuid(struct afs_call *call, struct sk_buff *skb,
case 1:
_debug("extract UUID");
ret = afs_extract_data(call, skb, last, call->buffer,
11 * sizeof(__be32));
ret = afs_extract_data(call, call->buffer,
11 * sizeof(__be32), false);
switch (ret) {
case 0: break;
case -EAGAIN: return 0;
@@ -487,16 +507,9 @@ static int afs_deliver_cb_probe_uuid(struct afs_call *call, struct sk_buff *skb,
call->unmarshall++;
case 2:
_debug("trailer");
if (skb->len != 0)
return -EBADMSG;
break;
}
ret = afs_data_complete(call, skb, last);
if (ret < 0)
return ret;
call->state = AFS_CALL_REPLYING;
INIT_WORK(&call->work, SRXAFSCB_ProbeUuid);
@@ -570,14 +583,13 @@ static void SRXAFSCB_TellMeAboutYourself(struct work_struct *work)
/*
* deliver request data to a CB.TellMeAboutYourself call
*/
static int afs_deliver_cb_tell_me_about_yourself(struct afs_call *call,
struct sk_buff *skb, bool last)
static int afs_deliver_cb_tell_me_about_yourself(struct afs_call *call)
{
int ret;
_enter(",{%u},%d", skb->len, last);
_enter("");
ret = afs_data_complete(call, skb, last);
ret = afs_extract_data(call, NULL, 0, false);
if (ret < 0)
return ret;