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>
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

View File

@@ -235,16 +235,15 @@ static void xdr_decode_AFSFetchVolumeStatus(const __be32 **_bp,
/*
* deliver reply data to an FS.FetchStatus
*/
static int afs_deliver_fs_fetch_status(struct afs_call *call,
struct sk_buff *skb, bool last)
static int afs_deliver_fs_fetch_status(struct afs_call *call)
{
struct afs_vnode *vnode = call->reply;
const __be32 *bp;
int ret;
_enter(",,%u", last);
_enter("");
ret = afs_transfer_reply(call, skb, last);
ret = afs_transfer_reply(call);
if (ret < 0)
return ret;
@@ -307,8 +306,7 @@ int afs_fs_fetch_file_status(struct afs_server *server,
/*
* deliver reply data to an FS.FetchData
*/
static int afs_deliver_fs_fetch_data(struct afs_call *call,
struct sk_buff *skb, bool last)
static int afs_deliver_fs_fetch_data(struct afs_call *call)
{
struct afs_vnode *vnode = call->reply;
const __be32 *bp;
@@ -316,7 +314,7 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call,
void *buffer;
int ret;
_enter("{%u},{%u},%d", call->unmarshall, skb->len, last);
_enter("{%u}", call->unmarshall);
switch (call->unmarshall) {
case 0:
@@ -332,7 +330,7 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call,
* client) */
case 1:
_debug("extract data length (MSW)");
ret = afs_extract_data(call, skb, last, &call->tmp, 4);
ret = afs_extract_data(call, &call->tmp, 4, true);
if (ret < 0)
return ret;
@@ -347,7 +345,7 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call,
/* extract the returned data length */
case 2:
_debug("extract data length");
ret = afs_extract_data(call, skb, last, &call->tmp, 4);
ret = afs_extract_data(call, &call->tmp, 4, true);
if (ret < 0)
return ret;
@@ -363,10 +361,10 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call,
_debug("extract data");
if (call->count > 0) {
page = call->reply3;
buffer = kmap_atomic(page);
ret = afs_extract_data(call, skb, last, buffer,
call->count);
kunmap_atomic(buffer);
buffer = kmap(page);
ret = afs_extract_data(call, buffer,
call->count, true);
kunmap(buffer);
if (ret < 0)
return ret;
}
@@ -376,8 +374,8 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call,
/* extract the metadata */
case 4:
ret = afs_extract_data(call, skb, last, call->buffer,
(21 + 3 + 6) * 4);
ret = afs_extract_data(call, call->buffer,
(21 + 3 + 6) * 4, false);
if (ret < 0)
return ret;
@@ -391,18 +389,15 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call,
call->unmarshall++;
case 5:
ret = afs_data_complete(call, skb, last);
if (ret < 0)
return ret;
break;
}
if (call->count < PAGE_SIZE) {
_debug("clear");
page = call->reply3;
buffer = kmap_atomic(page);
buffer = kmap(page);
memset(buffer + call->count, 0, PAGE_SIZE - call->count);
kunmap_atomic(buffer);
kunmap(buffer);
}
_leave(" = 0 [done]");
@@ -515,13 +510,12 @@ int afs_fs_fetch_data(struct afs_server *server,
/*
* deliver reply data to an FS.GiveUpCallBacks
*/
static int afs_deliver_fs_give_up_callbacks(struct afs_call *call,
struct sk_buff *skb, bool last)
static int afs_deliver_fs_give_up_callbacks(struct afs_call *call)
{
_enter(",{%u},%d", skb->len, last);
_enter("");
/* shouldn't be any reply data */
return afs_data_complete(call, skb, last);
return afs_extract_data(call, NULL, 0, false);
}
/*
@@ -599,16 +593,15 @@ int afs_fs_give_up_callbacks(struct afs_server *server,
/*
* deliver reply data to an FS.CreateFile or an FS.MakeDir
*/
static int afs_deliver_fs_create_vnode(struct afs_call *call,
struct sk_buff *skb, bool last)
static int afs_deliver_fs_create_vnode(struct afs_call *call)
{
struct afs_vnode *vnode = call->reply;
const __be32 *bp;
int ret;
_enter("{%u},{%u},%d", call->unmarshall, skb->len, last);
_enter("{%u}", call->unmarshall);
ret = afs_transfer_reply(call, skb, last);
ret = afs_transfer_reply(call);
if (ret < 0)
return ret;
@@ -696,16 +689,15 @@ int afs_fs_create(struct afs_server *server,
/*
* deliver reply data to an FS.RemoveFile or FS.RemoveDir
*/
static int afs_deliver_fs_remove(struct afs_call *call,
struct sk_buff *skb, bool last)
static int afs_deliver_fs_remove(struct afs_call *call)
{
struct afs_vnode *vnode = call->reply;
const __be32 *bp;
int ret;
_enter("{%u},{%u},%d", call->unmarshall, skb->len, last);
_enter("{%u}", call->unmarshall);
ret = afs_transfer_reply(call, skb, last);
ret = afs_transfer_reply(call);
if (ret < 0)
return ret;
@@ -777,16 +769,15 @@ int afs_fs_remove(struct afs_server *server,
/*
* deliver reply data to an FS.Link
*/
static int afs_deliver_fs_link(struct afs_call *call,
struct sk_buff *skb, bool last)
static int afs_deliver_fs_link(struct afs_call *call)
{
struct afs_vnode *dvnode = call->reply, *vnode = call->reply2;
const __be32 *bp;
int ret;
_enter("{%u},{%u},%d", call->unmarshall, skb->len, last);
_enter("{%u}", call->unmarshall);
ret = afs_transfer_reply(call, skb, last);
ret = afs_transfer_reply(call);
if (ret < 0)
return ret;
@@ -863,16 +854,15 @@ int afs_fs_link(struct afs_server *server,
/*
* deliver reply data to an FS.Symlink
*/
static int afs_deliver_fs_symlink(struct afs_call *call,
struct sk_buff *skb, bool last)
static int afs_deliver_fs_symlink(struct afs_call *call)
{
struct afs_vnode *vnode = call->reply;
const __be32 *bp;
int ret;
_enter("{%u},{%u},%d", call->unmarshall, skb->len, last);
_enter("{%u}", call->unmarshall);
ret = afs_transfer_reply(call, skb, last);
ret = afs_transfer_reply(call);
if (ret < 0)
return ret;
@@ -968,16 +958,15 @@ int afs_fs_symlink(struct afs_server *server,
/*
* deliver reply data to an FS.Rename
*/
static int afs_deliver_fs_rename(struct afs_call *call,
struct sk_buff *skb, bool last)
static int afs_deliver_fs_rename(struct afs_call *call)
{
struct afs_vnode *orig_dvnode = call->reply, *new_dvnode = call->reply2;
const __be32 *bp;
int ret;
_enter("{%u},{%u},%d", call->unmarshall, skb->len, last);
_enter("{%u}", call->unmarshall);
ret = afs_transfer_reply(call, skb, last);
ret = afs_transfer_reply(call);
if (ret < 0)
return ret;
@@ -1072,16 +1061,15 @@ int afs_fs_rename(struct afs_server *server,
/*
* deliver reply data to an FS.StoreData
*/
static int afs_deliver_fs_store_data(struct afs_call *call,
struct sk_buff *skb, bool last)
static int afs_deliver_fs_store_data(struct afs_call *call)
{
struct afs_vnode *vnode = call->reply;
const __be32 *bp;
int ret;
_enter(",,%u", last);
_enter("");
ret = afs_transfer_reply(call, skb, last);
ret = afs_transfer_reply(call);
if (ret < 0)
return ret;
@@ -1251,17 +1239,16 @@ int afs_fs_store_data(struct afs_server *server, struct afs_writeback *wb,
/*
* deliver reply data to an FS.StoreStatus
*/
static int afs_deliver_fs_store_status(struct afs_call *call,
struct sk_buff *skb, bool last)
static int afs_deliver_fs_store_status(struct afs_call *call)
{
afs_dataversion_t *store_version;
struct afs_vnode *vnode = call->reply;
const __be32 *bp;
int ret;
_enter(",,%u", last);
_enter("");
ret = afs_transfer_reply(call, skb, last);
ret = afs_transfer_reply(call);
if (ret < 0)
return ret;
@@ -1443,14 +1430,13 @@ int afs_fs_setattr(struct afs_server *server, struct key *key,
/*
* deliver reply data to an FS.GetVolumeStatus
*/
static int afs_deliver_fs_get_volume_status(struct afs_call *call,
struct sk_buff *skb, bool last)
static int afs_deliver_fs_get_volume_status(struct afs_call *call)
{
const __be32 *bp;
char *p;
int ret;
_enter("{%u},{%u},%d", call->unmarshall, skb->len, last);
_enter("{%u}", call->unmarshall);
switch (call->unmarshall) {
case 0:
@@ -1460,8 +1446,8 @@ static int afs_deliver_fs_get_volume_status(struct afs_call *call,
/* extract the returned status record */
case 1:
_debug("extract status");
ret = afs_extract_data(call, skb, last, call->buffer,
12 * 4);
ret = afs_extract_data(call, call->buffer,
12 * 4, true);
if (ret < 0)
return ret;
@@ -1472,7 +1458,7 @@ static int afs_deliver_fs_get_volume_status(struct afs_call *call,
/* extract the volume name length */
case 2:
ret = afs_extract_data(call, skb, last, &call->tmp, 4);
ret = afs_extract_data(call, &call->tmp, 4, true);
if (ret < 0)
return ret;
@@ -1487,8 +1473,8 @@ static int afs_deliver_fs_get_volume_status(struct afs_call *call,
case 3:
_debug("extract volname");
if (call->count > 0) {
ret = afs_extract_data(call, skb, last, call->reply3,
call->count);
ret = afs_extract_data(call, call->reply3,
call->count, true);
if (ret < 0)
return ret;
}
@@ -1508,8 +1494,8 @@ static int afs_deliver_fs_get_volume_status(struct afs_call *call,
call->count = 4 - (call->count & 3);
case 4:
ret = afs_extract_data(call, skb, last, call->buffer,
call->count);
ret = afs_extract_data(call, call->buffer,
call->count, true);
if (ret < 0)
return ret;
@@ -1519,7 +1505,7 @@ static int afs_deliver_fs_get_volume_status(struct afs_call *call,
/* extract the offline message length */
case 5:
ret = afs_extract_data(call, skb, last, &call->tmp, 4);
ret = afs_extract_data(call, &call->tmp, 4, true);
if (ret < 0)
return ret;
@@ -1534,8 +1520,8 @@ static int afs_deliver_fs_get_volume_status(struct afs_call *call,
case 6:
_debug("extract offline");
if (call->count > 0) {
ret = afs_extract_data(call, skb, last, call->reply3,
call->count);
ret = afs_extract_data(call, call->reply3,
call->count, true);
if (ret < 0)
return ret;
}
@@ -1555,8 +1541,8 @@ static int afs_deliver_fs_get_volume_status(struct afs_call *call,
call->count = 4 - (call->count & 3);
case 7:
ret = afs_extract_data(call, skb, last, call->buffer,
call->count);
ret = afs_extract_data(call, call->buffer,
call->count, true);
if (ret < 0)
return ret;
@@ -1566,7 +1552,7 @@ static int afs_deliver_fs_get_volume_status(struct afs_call *call,
/* extract the message of the day length */
case 8:
ret = afs_extract_data(call, skb, last, &call->tmp, 4);
ret = afs_extract_data(call, &call->tmp, 4, true);
if (ret < 0)
return ret;
@@ -1581,8 +1567,8 @@ static int afs_deliver_fs_get_volume_status(struct afs_call *call,
case 9:
_debug("extract motd");
if (call->count > 0) {
ret = afs_extract_data(call, skb, last, call->reply3,
call->count);
ret = afs_extract_data(call, call->reply3,
call->count, true);
if (ret < 0)
return ret;
}
@@ -1595,26 +1581,17 @@ static int afs_deliver_fs_get_volume_status(struct afs_call *call,
call->unmarshall++;
/* extract the message of the day padding */
if ((call->count & 3) == 0) {
call->unmarshall++;
goto no_motd_padding;
}
call->count = 4 - (call->count & 3);
call->count = (4 - (call->count & 3)) & 3;
case 10:
ret = afs_extract_data(call, skb, last, call->buffer,
call->count);
ret = afs_extract_data(call, call->buffer,
call->count, false);
if (ret < 0)
return ret;
call->offset = 0;
call->unmarshall++;
no_motd_padding:
case 11:
ret = afs_data_complete(call, skb, last);
if (ret < 0)
return ret;
break;
}
@@ -1685,15 +1662,14 @@ int afs_fs_get_volume_status(struct afs_server *server,
/*
* deliver reply data to an FS.SetLock, FS.ExtendLock or FS.ReleaseLock
*/
static int afs_deliver_fs_xxxx_lock(struct afs_call *call,
struct sk_buff *skb, bool last)
static int afs_deliver_fs_xxxx_lock(struct afs_call *call)
{
const __be32 *bp;
int ret;
_enter("{%u},{%u},%d", call->unmarshall, skb->len, last);
_enter("{%u}", call->unmarshall);
ret = afs_transfer_reply(call, skb, last);
ret = afs_transfer_reply(call);
if (ret < 0)
return ret;