We moved the netlink attribute support from net to lib in order
for it to be available for general consumption.  However, parts
of the code (the bits that we don't need :) really depends on
NET because the target object is sk_buff.

This patch fixes this by wrapping them in CONFIG_NET.

Some EXPORTs have been moved to make this work.
Tested-by: NGeert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Netlink attribute parsing may be used even if CONFIG_NET is not set.
Move it from net/netlink to lib and control its inclusion based on the new
config symbol CONFIG_NLATTR, which is selected by CONFIG_NET.
Signed-off-by: NGeert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

validate_nla() currently doesn't allow empty nested attributes. This
makes userspace code unnecessarily complicated when starting and ending
the nested attribute is done by generic upper level code and the inner
attributes are dumped by a module.

Add a special case to accept empty nested attributes. When the nested
attribute is non empty, the same checks as before are performed.
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fix some doc comments to match function and attribute names in
net/netlink/attr.c.
Signed-off-by: NJulius Volz <juliusv@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Make nlmsg_trim(), nlmsg_cancel(), genlmsg_cancel(), and
nla_nest_cancel() void functions.

Return -EMSGSIZE instead of -1 if the provided message buffer is not
big enough.
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Used to append data to a message without a header or padding.
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This change allows the generic attribute interface to be used within
the netfilter subsystem where this flag was initially introduced.

The byte-order flag is yet unused, it's intended use is to
allow automatic byte order convertions for all atomic types.
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a nested compat attribute type that can be used to convert
attributes that contain a structure to nested attributes in a
backwards compatible way.
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch introduces a new NLA_BINARY attribute policy type with the
verification of simply checking the maximum length of the payload.

It also fixes a small typo in the example.
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Introduces a new attribute type NLA_NUL_STRING to support NUL
terminated strings. Attributes of this kind require to carry
a terminating NUL within the maximum specified in the policy.

The `old' NLA_STRING which is not required to be NUL terminated
is extended to provide means to specify a maximum length of the
string.

Aims at easing the pain with using nla_strlcpy() on temporary
buffers.
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Adds:
 nlmsg_get_pos()                 return current position in message
 nlmsg_trim()                    trim part of message
 nla_reserve_nohdr(skb, len)     reserve room for an attribute w/o hdr
 nla_put_nohdr(skb, len, data)   add attribute w/o hdr
 nla_find_nested()               find attribute in nested attributes

Fixes nlmsg_new() to take allocation flags and consider size.
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NJörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>

Introduces a new type-safe interface for netlink message and
attributes handling. The interface is fully binary compatible
with the old interface towards userspace. Besides type safety,
this interface features attribute validation capabilities,
simplified message contstruction, and documentation.

The resulting netlink code should be smaller, less error prone
and easier to understand.
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>