linux/fs/afs
David Howells 0e119b41b7 rxrpc: Limit the listening backlog
Limit the socket incoming call backlog queue size so that a remote client
can't pump in sufficient new calls that the server runs out of memory.  Note
that this is partially theoretical at the moment since whilst the number of
calls is limited, the number of packets trying to set up new calls is not.
This will be addressed in a later patch.

If the caller of listen() specifies a backlog INT_MAX, then they get the
current maximum; anything else greater than max_backlog or anything
negative incurs EINVAL.

The limit on the maximum queue size can be set by:

	echo N >/proc/sys/net/rxrpc/max_backlog

where 4<=N<=32.

Further, set the default backlog to 0, requiring listen() to be called
before we start actually queueing new calls.  Whilst this kind of is a
change in the UAPI, the caller can't actually *accept* new calls anyway
unless they've first called listen() to put the socket into the LISTENING
state - thus the aforementioned new calls would otherwise just sit there,
eating up kernel memory.  (Note that sockets that don't have a non-zero
service ID bound don't get incoming calls anyway.)

Given that the default backlog is now 0, make the AFS filesystem call
kernel_listen() to set the maximum backlog for itself.

Possible improvements include:

 (1) Trimming a too-large backlog to max_backlog when listen is called.

 (2) Trimming the backlog value whenever the value is used so that changes
     to max_backlog are applied to an open socket automatically.  Note that
     the AFS filesystem opens one socket and keeps it open for extended
     periods, so would miss out on changes to max_backlog.

 (3) Having a separate setting for the AFS filesystem.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-06-10 18:14:47 -07:00
..
afs_cm.h afs: support the CB.ProbeUuid RPC op 2008-04-29 08:06:26 -07:00
afs_fs.h AFS: implement file locking 2007-07-16 09:05:43 -07:00
afs_vl.h AFS: Fix silly characters in a comment 2011-07-20 20:48:03 -04:00
afs.h afs: Support interacting with multiple user namespaces 2013-02-13 06:00:51 -08:00
cache.c Fix common misspellings 2011-03-31 11:26:23 -03:00
callback.c workqueue: use mod_delayed_work() instead of cancel + queue 2012-08-13 16:27:37 -07:00
cell.c FS-Cache: Provide the ability to enable/disable cookies 2013-09-27 18:40:25 +01:00
cmservice.c AFS: Fix cache manager service handlers 2014-05-21 14:48:05 +01:00
dir.c afs: switch to ->iterate_shared() 2016-05-10 14:27:44 -04:00
file.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
flock.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
fsclient.c afs: Support interacting with multiple user namespaces 2013-02-13 06:00:51 -08:00
inode.c don't put symlink bodies in pagecache into highmem 2015-12-08 22:41:36 -05:00
internal.h Merge commit '9f12600fe425bc28f0ccba034a77783c09c15af4' into for-linus 2014-06-12 00:28:09 -04:00
Kconfig fs/afs: remove depends on CONFIG_EXPERIMENTAL 2013-01-21 14:39:04 -08:00
main.c AFS: Correctly assemble the client UUID 2014-07-29 10:14:36 -07:00
Makefile FS-Cache: Make kAFS use FS-Cache 2009-04-03 16:42:41 +01:00
misc.c kafs: Add more "unified AFS" error codes 2015-04-01 21:36:15 +01:00
mntpt.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
netdevices.c afs: BUG to BUG_ON changes 2009-04-09 10:41:19 -07:00
proc.c convert a bunch of open-coded instances of memdup_user_nul() 2016-01-04 10:26:58 -05:00
rxrpc.c rxrpc: Limit the listening backlog 2016-06-10 18:14:47 -07:00
security.c ->permission() sanitizing: don't pass flags to ->permission() 2011-07-20 01:43:24 -04:00
server.c workqueue: use mod_delayed_work() instead of cancel + queue 2012-08-13 16:27:37 -07:00
super.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
vlclient.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
vlocation.c sched, cleanup, treewide: Remove set_current_state(TASK_RUNNING) after schedule() 2014-09-19 12:35:17 +02:00
vnode.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
volume.c fs: introduce f_op->mmap_capabilities for nommu mmap support 2015-01-20 14:02:58 -07:00
write.c remove lots of IS_ERR_VALUE abuses 2016-05-27 15:26:11 -07:00