linux.git/net/ipv4/netfilter, branch v4.8-rc2

netfilter: x_tables: speed up jump target validation

2016-07-18T19:35:23+00:00

The dummy ruleset I used to test the original validation change was broken,
most rules were unreachable and were not tested by mark_source_chains().

In some cases rulesets that used to load in a few seconds now require
several minutes.

sample ruleset that shows the behaviour:

echo "*filter"
for i in $(seq 0 100000);do
        printf ":chain_%06x - [0:0]\n" $i
done
for i in $(seq 0 100000);do
   printf -- "-A INPUT -j chain_%06x\n" $i
   printf -- "-A INPUT -j chain_%06x\n" $i
   printf -- "-A INPUT -j chain_%06x\n" $i
done
echo COMMIT

[ pipe result into iptables-restore ]

This ruleset will be about 74mbyte in size, with ~500k searches
though all 500k[1] rule entries. iptables-restore will take forever
(gave up after 10 minutes)

Instead of always searching the entire blob for a match, fill an
array with the start offsets of every single ipt_entry struct,
then do a binary search to check if the jump target is present or not.

After this change ruleset restore times get again close to what one
gets when reverting 36472341017529e (~3 seconds on my workstation).

[1] every user-defined rule gets an implicit RETURN, so we get
300k jumps + 100k userchains + 100k returns -> 500k rule entries

Fixes: 36472341017529e ("netfilter: x_tables: validate targets of jumps")
Reported-by: Jeff Wu 
Tested-by: Jeff Wu 
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

netfilter: conntrack: fix race between nf_conntrack proc read and hash resize

2016-07-11T09:38:57+00:00

When we do "cat /proc/net/nf_conntrack", and meanwhile resize the conntrack
hash table via /sys/module/nf_conntrack/parameters/hashsize, race will
happen, because reader can observe a newly allocated hash but the old size
(or vice versa). So oops will happen like follows：

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000017
  IP: [] seq_print_acct+0x11/0x50 [nf_conntrack]
  Call Trace:
  [] ? ct_seq_show+0x14e/0x340 [nf_conntrack]
  [] seq_read+0x2cc/0x390
  [] proc_reg_read+0x42/0x70
  [] __vfs_read+0x37/0x130
  [] ? security_file_permission+0xa0/0xc0
  [] vfs_read+0x95/0x140
  [] SyS_read+0x55/0xc0
  [] entry_SYSCALL_64_fastpath+0x1a/0xa4

It is very easy to reproduce this kernel crash.
1. open one shell and input the following cmds:
  while : ; do
    echo $RANDOM > /sys/module/nf_conntrack/parameters/hashsize
  done
2. open more shells and input the following cmds:
  while : ; do
    cat /proc/net/nf_conntrack
  done
3. just wait a monent, oops will happen soon.

The solution in this patch is based on Florian's Commit 5e3c61f98175
("netfilter: conntrack: fix lookup race during hash resize"). And
add a wrapper function nf_conntrack_get_ht to get hash and hsize
suggested by Florian Westphal.

Signed-off-by: Liping Zhang 
Signed-off-by: Pablo Neira Ayuso

netfilter: Convert FWINV<[foo]> macros and uses to NF_INVF

2016-07-03T08:55:07+00:00

netfilter uses multiple FWINV #defines with identical form that hide a
specific structure variable and dereference it with a invflags member.

$ git grep "#define FWINV"
include/linux/netfilter_bridge/ebtables.h:#define FWINV(bool,invflg) ((bool) ^ !!(info->invflags & invflg))
net/bridge/netfilter/ebtables.c:#define FWINV2(bool, invflg) ((bool) ^ !!(e->invflags & invflg))
net/ipv4/netfilter/arp_tables.c:#define FWINV(bool, invflg) ((bool) ^ !!(arpinfo->invflags & (invflg)))
net/ipv4/netfilter/ip_tables.c:#define FWINV(bool, invflg) ((bool) ^ !!(ipinfo->invflags & (invflg)))
net/ipv6/netfilter/ip6_tables.c:#define FWINV(bool, invflg) ((bool) ^ !!(ip6info->invflags & (invflg)))
net/netfilter/xt_tcpudp.c:#define FWINVTCP(bool, invflg) ((bool) ^ !!(tcpinfo->invflags & (invflg)))

Consolidate these macros into a single NF_INVF macro.

Miscellanea:

o Neaten the alignment around these uses
o A few lines are > 80 columns for intelligibility

Signed-off-by: Joe Perches 
Signed-off-by: Pablo Neira Ayuso

netfilter: x_tables: simplify ip{6}table_mangle_hook()

2016-07-01T14:37:02+00:00

No need for a special case to handle NF_INET_POST_ROUTING, this is
basically the same handling as for prerouting, input, forward.

Signed-off-by: Pablo Neira Ayuso

netfilter: nf_reject_ipv4: don't send tcp RST if the packet is non-TCP

2016-06-24T09:03:22+00:00

In iptables, if the user add a rule to send tcp RST and specify the
non-TCP protocol, such as UDP, kernel will reject this request. But
in nftables, this validity check only occurs in nft tool, i.e. only
in userspace.

This means that user can add such a rule like follows via nfnetlink:
  "nft add rule filter forward ip protocol udp reject with tcp reset"

This will generate some confusing tcp RST packets. So we should send
tcp RST only when it is TCP packet.

Signed-off-by: Liping Zhang 
Signed-off-by: Pablo Neira Ayuso

netfilter: conntrack: use a single expectation table for all namespaces

2016-05-06T09:50:01+00:00

We already include netns address in the hash and compare the netns pointers
during lookup, so even if namespaces have overlapping addresses entries
will be spread across the expectation table.

Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

netfilter: conntrack: check netns when walking expect hash

2016-05-06T09:50:01+00:00

Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

netfilter: x_tables: get rid of old and inconsistent debugging

2016-05-05T14:39:51+00:00

The dprintf() and duprintf() functions are enabled at compile time,
these days we have better runtime debugging through pr_debug() and
static keys.

On top of this, this debugging is so old that I don't expect anyone
using this anymore, so let's get rid of this.

IP_NF_ASSERT() is still left in place, although this needs that
NETFILTER_DEBUG is enabled, I think these assertions provide useful
context information when reading the code.

Note that ARP_NF_ASSERT() has been removed as there is no user of
this.

Kill also DEBUG_ALLOW_ALL and a couple of pr_error() and pr_debug()
spots that are inconsistently placed in the code.

Signed-off-by: Pablo Neira Ayuso

netfilter: conntrack: use a single hashtable for all namespaces

2016-05-05T14:39:47+00:00

We already include netns address in the hash and compare the netns pointers
during lookup, so even if namespaces have overlapping addresses entries
will be spread across the table.

Assuming 64k bucket size, this change saves 0.5 mbyte per namespace on a
64bit system.

NAT bysrc and expectation hash is still per namespace, those will
changed too soon.

Future patch will also make conntrack object slab cache global again.

Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

netfilter: conntrack: check netns when comparing conntrack objects

2016-05-05T14:39:46+00:00

Once we place all conntracks in the same hash table we must also compare
the netns pointer to skip conntracks that belong to a different namespace.

Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso