This patch removes unnecessary logspam which resulted from superfluous
calls to net_ratelimit(). With the supplied patch, net_ratelimit() is
called after the loglevel has been checked.
Signed-off-by: André Gaul <gaul@web-yard.de>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
On some architectures ether_addr_copy() is slightly faster
than memcpy() therefore use the former when possible.
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
When the TVLV parsing routine succeed the skb is left
untouched thus leading to a memory leak.
Fix this by consuming the skb in case of success.
Introduced by ef26157747
("batman-adv: tvlv - basic infrastructure")
Reported-by: Russel Senior <russell@personaltelco.net>
Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
Tested-by: Russell Senior <russell@personaltelco.net>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
pskb_may_pull() returns 1 on success and 0 in case of failure,
therefore checking for the return value being negative does
not make sense at all.
This way if the function fails we will probably read beyond the current
skb data buffer. Fix this by doing the proper check.
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
With the new interface alternating, the first hop may send packets
in a round robin fashion to it's neighbors because it has multiple
valid routes built by the multi interface optimization. This patch
enables the feature if bonding is selected. Note that unlike the
bonding implemented before, this version is much simpler and may
even enable multi path routing to a certain degree.
Signed-off-by: Simon Wunderlich <simon@open-mesh.com>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
For the network wide multi interface optimization there are different
routers for each outgoing interface (outgoing from the OGM perspective,
incoming for payload traffic). To reflect this, change the router and
associated data to a list of routers.
While at it, rename batadv_orig_node_get_router() to
batadv_orig_router_get() to follow the new naming scheme.
Signed-off-by: Simon Wunderlich <simon@open-mesh.com>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
Remove bonding and interface alternating code - it will be replaced
by a new, network-wide multi interface optimization which enables
both bonding and interface alternating in a better way.
Keep the sysfs and find router function though, this will be needed
later.
Signed-off-by: Simon Wunderlich <simon@open-mesh.com>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
As suggested by checkpatch, remove all the references to the
FSF address since the kernel already has one reference in
its documentation.
In this way it is easier to update it in case of future
changes.
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
If possible, operations like ntohs/ntohl should not be
performed too often. Use a variable to locally store the
converted value and then use it.
Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
struct batadv_icmp_header currently has a size of 17, which
will be padded to 20 on some architectures. Fix this by
unrolling the header into the parent structures.
Moreover keep the ICMP parsing functions as generic as they
are now by using a stub icmp_header struct during packet
parsing.
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
The size of the batadv_header of 3 is problematic on some architectures
which automatically pad all structures to a 32 bit boundary. To not lose
performance by packing this struct, better embed it into the various
host structures.
Reported-by: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
Instead of handling icmp packets only up to length of icmp_packet_rr,
the code should handle any icmp length size. Therefore the length
truncating is moved to when the packet is actually sent to userspace
(this does not support lengths longer than icmp_packet_rr yet). Longer
packets are forwarded without truncating.
This patch also cleans up some parts where the icmp header struct could
be used instead of other icmp_packet(_rr) structs to make the code more
readable.
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
some of the fields in struct batadv_neigh_node are strictly
related to the B.A.T.M.A.N. IV algorithm. In order to
make the struct usable by any routing algorithm it has to be
split and made more generic
Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Instead of unconditionally removing all the TT entries
served by a given originator, make tt_global_orig_del()
remove only entries matching a given VLAN identifier
provided as argument.
If such argument is negative all the global entries
served by the originator are removed.
This change is used into the BLA code to purge entries
served by a newly discovered Backbone node, but limiting
the operation only to those connected to the VLAN where the
backbone has been discovered.
Cc: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
To make the translation table code VLAN-aware, each entry
must carry the VLAN ID which it belongs to. This patch adds
such attribute to the related TT structures.
Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
the icmp and the icmp_rr packets share the same initial
fields since they use the same code to be processed and
forwarded.
Extract the common fields and put them into a separate
struct so that future ICMP packets can be easily added
without bloating the packet definition.
However, keep the seqno field outside of the newly created
common header because future ICMP types may require a
bigger sequence number space.
This change breaks compatibility due to fields reordering
in the ICMP headers.
Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Fragments arriving at their destination are buffered for later merge.
Merged packets are passed to the main receive function as had they never
been fragmented.
Fragments are forwarded without merging if the MTU of the outgoing
interface is smaller than the size of the merged packet.
Signed-off-by: Martin Hundebøll <martin@hundeboll.net>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
Remove the existing fragmentation code before adding the new version
and delete unicast.{h,c}.
batadv_unicast_send_skb() is moved to send.c and renamed to
batadv_send_skb_unicast().
fragmentation entry in sysfs (bat_priv->fragmentation) is kept for use in
the new fragmentation code.
BATADV_UNICAST_FRAG packet type is renamed to BATADV_FRAG for use in the
new fragmentation code.
Signed-off-by: Martin Hundebøll <martin@hundeboll.net>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
Adding host information for record route is only required for ICMP
requests and replys, and should not be added to just any (future?)
packet type.
Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
Reordering the packet type numbers allows us to handle unicast
packets in a general way - even if we don't know the specific packet
type, we can still forward it. There was already code handling
this for a couple of unicast packets, and this is the more
generalized version to do that.
Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
This is replaced by a userspace program, we don't need this
functionality to bloat the kernel.
Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
Instead of generating roaming specific packets the TVLV unicast API is
used to send roaming information.
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
Instead of generating TT specific packets the TVLV unicast API is used
to send translation table data.
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
The goal is to provide the infrastructure for sending, receiving and
parsing information 'containers' while preserving backward
compatibility. TVLV (based on the commonly known Type Length Value
technique) was chosen as the format for those containers. Even if a
node does not know the tvlv type of a certain container it can simply
skip the current container and proceed with the next. Past experience
has shown features evolve over time, so a 'version' field was added
right from the start to allow differentiating between feature
variants - hence the name: T(ype) V(ersion) L(ength) V(alue).
This patch introduces the basic TVLV infrastructure:
* register / unregister tvlv containers to be sent with each OGM
(on primary interfaces only)
* register / unregister callback handlers to be called upon
finding the corresponding tvlv type in a tvlv buffer
* unicast tvlv send / receive API calls
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Spyros Gasteratos <morfeas3000@gmail.com>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
The skb priority field may help the wireless driver to choose the right
queue (e.g. WMM queues). This should be set in batman-adv, as this
information is only available here.
This patch adds support for IPv4/IPv6 DS fields and VLAN PCP. Note that
only VLAN PCP is used if a VLAN header is present. Also initially set
TC_PRIO_CONTROL only for self-generated packets, and keep the priority
set by higher layers.
Signed-off-by: Simon Wunderlich <simon@open-mesh.com>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
The call to batadv_nc_skb_forward() fits better in
batadv_send_skb_to_orig(), as this is where the actual next hop is
looked up.
To let the caller of batadv_send_skb_to_orig() know wether the skb is
transmitted, buffered or failed, the return value is changed from
boolean to int.
Signed-off-by: Martin Hundebøll <martin@hundeboll.net>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
batadv_slide_own_bcast_window() is used only in bat_iv_ogm.c
and it is currently touching only batman_iv specific
attributes.
Move it into bat_iv_ogm.c and make it static.
Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Instead of casting the result of skb_mac_header() to
"struct ethhdr *" every time, the eth_hdr inline function
can be use to beautify the code and improve its readability.
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Conflicts:
drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
drivers/net/ethernet/emulex/benet/be.h
include/net/tcp.h
net/mac802154/mac802154.h
Most conflicts were minor overlapping stuff.
The be2net driver brought in some fixes that added __vlan_put_tag
calls, which in net-next take an additional argument.
Signed-off-by: David S. Miller <davem@davemloft.net>
Conflicts:
drivers/net/ethernet/emulex/benet/be_main.c
drivers/net/ethernet/intel/igb/igb_main.c
drivers/net/wireless/brcm80211/brcmsmac/mac80211_if.c
include/net/scm.h
net/batman-adv/routing.c
net/ipv4/tcp_input.c
The e{uid,gid} --> {uid,gid} credentials fix conflicted with the
cleanup in net-next to now pass cred structs around.
The be2net driver had a bug fix in 'net' that overlapped with the VLAN
interface changes by Patrick McHardy in net-next.
An IGB conflict existed because in 'net' the build_skb() support was
reverted, and in 'net-next' there was a comment style fix within that
code.
Several batman-adv conflicts were resolved by making sure that all
calls to batadv_is_my_mac() are changed to have a new bat_priv first
argument.
Eric Dumazet's TS ECR fix in TCP in 'net' conflicted with the F-RTO
rewrite in 'net-next', mostly overlapping changes.
Thanks to Stephen Rothwell and Antonio Quartulli for help with several
of these merge resolutions.
Signed-off-by: David S. Miller <davem@davemloft.net>
Unicast packet might be of type either UNICAST or
UNICAST4ADDR.
In the two cases the header size is different, but the
mechanism checking the TTVN field was assuming it to be
always of the same type (UNICAST), so failing to access the
inner Ethernet header in case of UNICAST4ADDR.
Fix this by passing the real header length as argument.
Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
On a multi-mesh node (a node running more than one batman-adv
virtual interface) batadv_is_my_mac() has to check MAC
addresses of hard interfaces belonging to the current mesh
only.
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
To be able to decode a network coded packet, a node must already know
one of the two coded packets. This is done by buffering skbs before
transmission and buffering packets sniffed with promiscuous mode from
other hosts.
Packets are kept in a buffer similar to the one with forward-skbs: A
hash table, where each entry, which corresponds to a src-dst pair, has a
linked list packets.
Signed-off-by: Martin Hundebøll <martin@hundeboll.net>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Two be able to network code two packets, one packet must be buffered
until the next is available. This is done in a "coding buffer", which is
essentially a hash table with lists of packets. Each entry in the hash
table corresponds to a specific src-dst pair, which has a linked list of
packets that are buffered.
This patch adds skbs to the buffer just before forwarding them. The
buffer is traversed every 10 ms, where timed skbs are removed from the
buffer and transmitted. To allow experiments with the network coding
scheme, the timeout is tunable through a file in debugfs.
Signed-off-by: Martin Hundebøll <martin@hundeboll.net>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
batadv_check_unicast_packet() is changed to return a value based on the
reason to drop the packet, which will be useful information for
future users of batadv_check_unicast_packet().
Signed-off-by: Martin Hundebøll <martin@hundeboll.net>
Acked-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
I'm not sure why, but the hlist for each entry iterators were conceived
list_for_each_entry(pos, head, member)
The hlist ones were greedy and wanted an extra parameter:
hlist_for_each_entry(tpos, pos, head, member)
Why did they need an extra pos parameter? I'm not quite sure. Not only
they don't really need it, it also prevents the iterator from looking
exactly like the list iterator, which is unfortunate.
Besides the semantic patch, there was some manual work required:
- Fix up the actual hlist iterators in linux/list.h
- Fix up the declaration of other iterators based on the hlist ones.
- A very small amount of places were using the 'node' parameter, this
was modified to use 'obj->member' instead.
- Coccinelle didn't handle the hlist_for_each_entry_safe iterator
properly, so those had to be fixed up manually.
The semantic patch which is mostly the work of Peter Senna Tschudin is here:
@@
iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host;
type T;
expression a,c,d,e;
identifier b;
statement S;
@@
-T b;
<+... when != b
(
hlist_for_each_entry(a,
- b,
c, d) S
|
hlist_for_each_entry_continue(a,
- b,
c) S
|
hlist_for_each_entry_from(a,
- b,
c) S
|
hlist_for_each_entry_rcu(a,
- b,
c, d) S
|
hlist_for_each_entry_rcu_bh(a,
- b,
c, d) S
|
hlist_for_each_entry_continue_rcu_bh(a,
- b,
c) S
|
for_each_busy_worker(a, c,
- b,
d) S
|
ax25_uid_for_each(a,
- b,
c) S
|
ax25_for_each(a,
- b,
c) S
|
inet_bind_bucket_for_each(a,
- b,
c) S
|
sctp_for_each_hentry(a,
- b,
c) S
|
sk_for_each(a,
- b,
c) S
|
sk_for_each_rcu(a,
- b,
c) S
|
sk_for_each_from
-(a, b)
+(a)
S
+ sk_for_each_from(a) S
|
sk_for_each_safe(a,
- b,
c, d) S
|
sk_for_each_bound(a,
- b,
c) S
|
hlist_for_each_entry_safe(a,
- b,
c, d, e) S
|
hlist_for_each_entry_continue_rcu(a,
- b,
c) S
|
nr_neigh_for_each(a,
- b,
c) S
|
nr_neigh_for_each_safe(a,
- b,
c, d) S
|
nr_node_for_each(a,
- b,
c) S
|
nr_node_for_each_safe(a,
- b,
c, d) S
|
- for_each_gfn_sp(a, c, d, b) S
+ for_each_gfn_sp(a, c, d) S
|
- for_each_gfn_indirect_valid_sp(a, c, d, b) S
+ for_each_gfn_indirect_valid_sp(a, c, d) S
|
for_each_host(a,
- b,
c) S
|
for_each_host_safe(a,
- b,
c, d) S
|
for_each_mesh_entry(a,
- b,
c, d) S
)
...+>
[akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c]
[akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c]
[akpm@linux-foundation.org: checkpatch fixes]
[akpm@linux-foundation.org: fix warnings]
[akpm@linux-foudnation.org: redo intrusive kvm changes]
Tested-by: Peter Senna Tschudin <peter.senna@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If the skb is fragmented, the checksum must be computed on the
individual fragments, just using skb->data may fail on fragmented
data. Instead of doing linearizing the packet, use the new
batadv_crc32 to do that more efficiently- it should not hurt
replacing the old crc16 by the new crc32.
Reported-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
By adding batadv_send_skb_to_orig() in send.c, we can remove duplicate
code that looks up the next hop and then calls batadv_send_skb_packet().
Furthermore, this prepares the upcoming new implementation of
fragmentation, which requires the next hop to route packets.
Please note that this doesn't entirely remove the next-hop lookup in
routing.c and unicast.c, since it is used by the current fragmentation
code.
Also note that the next-hop info is removed from debug messages in
translation-table.c, since it is looked up elsewhere.
Signed-off-by: Martin Hundebøll <martin@hundeboll.net>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
tt_poss_change is a node-wide flag which tells whether the node is in a roaming
state (a client recently moved to/away from it) in order to let it apply special
re-routing rules. However this flag does not give a clear idea of the current
state because it is not possible to understand *which client* is actually
involved in the roaming. For this reason a better approach has been chosen:
instead of using a node-wide variable, the roaming state is now given by a
per-tt_entry ROAM flag which, in case of packet coming through the node, tells
the node whether the real destination is in roaming state or not.
With this flag change, batadv_check_unicast_ttvn() has also been rearranged in
order to better fit the new re-routing logic and to be much more readable.
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
The "early client detection mechanism" can be extended to find new clients by
means of unicast_4addr packets.
The unicast_4addr packet contains as well as the broadcast packet (which is
currently used in this mechanism) the address of the originating node and can
therefore be used to install new entries in the Global Translation Table
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
In case of an ARP message going in or out the soft_iface, it is intercepted and
a special action is performed. In particular the DHT helper functions previously
implemented are used to store all the ARP entries belonging to the network in
order to provide a fast and unicast lookup instead of the classic broadcast
flooding mechanism.
Each node stores the entries it is responsible for (following the DHT rules) in
its soft_iface ARP table. This makes it possible to reuse the kernel data
structures and functions for ARP management.
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
The current unicast packet type does not contain the orig source address. This
patches add a new unicast packet (called UNICAST_4ADDR) which provides two new
fields: the originator source address and the subtype (the type of the data
contained in the packet payload). The former is useful to identify the node
which injected the packet into the network and the latter is useful to avoid
creating new unicast packet types in the future: a macro defining a new subtype
will be enough.
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
In batadv_check_unicast_ttvn() the code accesses both the unicast header and the
Ethernet header in the payload. For this reason pskb_may_pull() must be invoked
to check for the required space.
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
To simplify TranslationTable debugging it is better to print the packet
rerouting message on the DBG_TT log level. In this way a developer interested in
packets rerouting doesn't need to filter it out of the whole ROUTES log.
Moreover, since this message will appear for each rerouted message, it is now
"ratelimited".
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
The test whether we can use a router for alternating bonding should only be
done once because it is already known that it is still usable and will not be
deleted from the list soon.
This patch addresses Coverity #712285: Unchecked return value
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
André Gaul
Antonio Quartulli
Antonio Quartulli
Simon Wunderlich
Simon Wunderlich
Martin Hundebøll
Simon Wunderlich
Simon Wunderlich
Marek Lindner
Antonio Quartulli
David S. Miller
Sasha Levin
Sven Eckelmann