netfilter: nf_tables: validate NFPROTO_* family

Several expressions explicitly refer to NF_INET_* hook definitions
from expr->ops->validate, however, family is not validated.

Bail out with EOPNOTSUPP in case they are used from unsupported
families.

Fixes: 0ca743a55991 ("netfilter: nf_tables: add compatibility layer for x_tables")
Fixes: a3c90f7a2323 ("netfilter: nf_tables: flow offload expression")
Fixes: 2fa841938c64 ("netfilter: nf_tables: introduce routing expression")
Fixes: 554ced0a6e29 ("netfilter: nf_tables: add support for native socket matching")
Fixes: ad49d86e07a4 ("netfilter: nf_tables: Add synproxy support")
Fixes: 4ed8eb6570a4 ("netfilter: nf_tables: Add native tproxy support")
Fixes: 6c47260250fc ("netfilter: nf_tables: add xfrm expression")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_tables: limit allowed range via nla_policy

These NLA_U32 types get stored in u8 fields, reject invalid values
instead of silently casting to u8.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_tables: Extend nft_expr_ops::dump callback parameters

Add a 'reset' flag just like with nft_object_ops::dump. This will be
useful to reset "anonymous stateful objects", e.g. simple rule counters.

No functional change intended.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_tproxy: restrict to prerouting hook

TPROXY is only allowed from prerouting, but nft_tproxy doesn't check this.
This fixes a crash (null dereference) when using tproxy from e.g. output.

Fixes: 4ed8eb6570a4 ("netfilter: nf_tables: Add native tproxy support")
Reported-by: Shell Chen <xierch@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>

netfilter: nf_tables: add and use BE register load-store helpers

Same as the existing ones, no conversions. This is just for sparse sake
only so that we no longer mix be16/u16 and be32/u32 types.

Alternative is to add __force __beX in various places, but this
seems nicer.

objdiff shows no changes.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_tables: do not reduce read-only expressions

Skip register tracking for expressions that perform read-only operations
on the registers. Define and use a cookie pointer NFT_REDUCE_READONLY to
avoid defining stubs for these expressions.

This patch re-enables register tracking which was disabled in ed5f85d42290
("netfilter: nf_tables: disable register tracking"). Follow up patches
add remaining register tracking for existing expressions.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_tproxy: restrict support to TCP and UDP transport protocols

Add unfront check for TCP and UDP packets before performing further
processing.

Fixes: 4ed8eb6570a4 ("netfilter: nf_tables: Add native tproxy support")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_tables: add and use nft_thoff helper

This allows to change storage placement later on without changing readers.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: disable defrag once its no longer needed

When I changed defrag hooks to no longer get registered by default I
intentionally made it so that registration can only be un-done by unloading
the nf_defrag_ipv4/6 module.

In hindsight this was too conservative; there is no reason to keep defrag
on while there is no feature dependency anymore.

Moreover, this won't work if user isn't allowed to remove nf_defrag module.

This adds the disable() functions for both ipv4 and ipv6 and calls them
from conntrack, TPROXY and the xtables socket module.

ipvs isn't converted here, it will behave as before this patch and
will need module removal.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nftables: add nft_parse_register_load() and use it

This new function combines the netlink register attribute parser
and the load validation function.

This update requires to replace:

enum nft_registers sreg:8;

in many of the expression private areas otherwise compiler complains
with:

error: cannot take address of bit-field ‘sreg’

when passing the register field as reference.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_tproxy: Fix port selector on Big Endian

On Big Endian architectures, u16 port value was extracted from the wrong
parts of u32 sreg_port, just like commit 10596608c4d62 ("netfilter:
nf_tables: fix mismatch in big-endian system") describes.

Fixes: 4ed8eb6570a49 ("netfilter: nf_tables: Add native tproxy support")
Signed-off-by: Phil Sutter <phil@nwl.cc>
Acked-by: Florian Westphal <fw@strlen.de>
Acked-by: Máté Eckl <ecklm94@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

treewide: Use sizeof_field() macro

Replace all the occurrences of FIELD_SIZEOF() with sizeof_field() except
at places where these are defined. Later patches will remove the unused
definition of FIELD_SIZEOF().

This patch is generated using following script:

EXCLUDE_FILES="include/linux/stddef.h|include/linux/kernel.h"

git grep -l -e "\bFIELD_SIZEOF\b" | while read file;
do

if [[ "$file" =~ $EXCLUDE_FILES ]]; then
continue
fi
sed -i -e 's/\bFIELD_SIZEOF\b/sizeof_field/g' $file;
done

Signed-off-by: Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@intel.com>
Link: https://lore.kernel.org/r/20190924105839.110713-3-pankaj.laxminarayan.bharadiya@intel.com
Co-developed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: David Miller <davem@davemloft.net> # for net

netfilter: nft_tproxy: Fix missing-braces warning

This patch fixes a warning reported by the kbuild test robot (from linux-next
tree):
net/netfilter/nft_tproxy.c: In function 'nft_tproxy_eval_v6':
>> net/netfilter/nft_tproxy.c:85:9: warning: missing braces around initializer [-Wmissing-braces]
struct in6_addr taddr = {0};
^
net/netfilter/nft_tproxy.c:85:9: warning: (near initialization for 'taddr.in6_u') [-Wmissing-braces]

This warning is actually caused by a gcc bug already resolved in newer
versions (kbuild used 4.9) so this kind of initialization is omitted and
memset is used instead.

Fixes: 4ed8eb6570a4 ("netfilter: nf_tables: Add native tproxy support")
Signed-off-by: Máté Eckl <ecklm94@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_tproxy: Add missing config check

A config check was missing form the code when using
nf_defrag_ipv6_enable with NFT_TPROXY != n and NF_DEFRAG_IPV6 = n and
this caused the following error:

../net/netfilter/nft_tproxy.c: In function 'nft_tproxy_init':
../net/netfilter/nft_tproxy.c:237:3: error: implicit declaration of function
+'nf_defrag_ipv6_enable' [-Werror=implicit-function-declaration]
err = nf_defrag_ipv6_enable(ctx->net);

This patch adds a check for NF_TABLES_IPV6 when NF_DEFRAG_IPV6 is
selected by Kconfig.

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Fixes: 4ed8eb6570a4 ("netfilter: nf_tables: Add native tproxy support")
Signed-off-by: Máté Eckl <ecklm94@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_tables: Add native tproxy support

A great portion of the code is taken from xt_TPROXY.c

There are some changes compared to the iptables implementation:
- tproxy statement is not terminal here
- Either address or port has to be specified, but at least one of them
is necessary. If one of them is not specified, the evaluation will be
performed with the original attribute of the packet (ie. target port
is not specified => the packet's dport will be used).

To make this work in inet tables, the tproxy structure has a family
member (typically called priv->family) which is not necessarily equal to
ctx->family.

priv->family can have three values legally:
- NFPROTO_IPV4 if the table family is ip OR if table family is inet,
but an ipv4 address is specified as a target address. The rule only
evaluates ipv4 packets in this case.
- NFPROTO_IPV6 if the table family is ip6 OR if table family is inet,
but an ipv6 address is specified as a target address. The rule only
evaluates ipv6 packets in this case.
- NFPROTO_UNSPEC if the table family is inet AND if only the port is
specified. The rule will evaluate both ipv4 and ipv6 packets.

Signed-off-by: Máté Eckl <ecklm94@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>