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
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afs_cm.h
afs_fs.h
afs_vl.h
afs.h
cache.c
callback.c
cell.c
cmservice.c
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
fsclient.c
inode.c
internal.h
Kconfig
main.c
Makefile
misc.c
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
proc.c
rxrpc.c	rxrpc: Limit the listening backlog	2016-06-10 18:14:47 -07:00
security.c
server.c
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
vlocation.c
vnode.c
volume.c
write.c	remove lots of IS_ERR_VALUE abuses	2016-05-27 15:26:11 -07:00