| Commit message (Collapse) | Author | Age | Files | Lines |
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Signed-off-by: Felix Janda <felix.janda@posteo.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds mark filter for event listener, using same struct
nfct_filter_dump_mark at dump.
Signed-off-by: Ken-ichirou MATSUZAWA <chamas@h4.dion.ne.jp>
Signed-off-by: Florian Westphal <fw@strlen.de>
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4b6df76 conntrack: fix autogenerated BPF code for IPv6 filtering aimed
to fix a bug the IPv6 BPF filtering. However, it didn't fix it for
NFCT_FILTER_LOGIC_POSITIVE case since jump is still miscalculated.
This chunk below shows the BPF code to filter IPv6 address 2:4:6::
{0x00020004, 0x00060000, 0x0, 0x0 } in case that NFCT_FILTER_LOGIC_POSITIVE
is used, ie. if that address matches, accept the event.
(0032) code= BPF_LD|BPF_W|BPF_IND jt=00 jf=00 k=00000004
(0033) code= BPF_ALU|BPF_AND|BPF_K jt=00 jf=00 k=ffffffff
(0034) code= BPF_JMP|BPF_JEQ|BPF_K jt=00 jf=09 k=00020004
[ this above compares second 4 bytes with 00020004, if comparison fails
it jumps to 003e ]
(0035) code= BPF_LD|BPF_W|BPF_IND jt=00 jf=00 k=00000008
(0036) code= BPF_ALU|BPF_AND|BPF_K jt=00 jf=00 k=ffffffff
(0037) code= BPF_JMP|BPF_JEQ|BPF_K jt=00 jf=06 k=00060000
[ this above compares second 4 bytes with 00060000, if comparison fails
it jumps to 003e ]
(0038) code= BPF_LD|BPF_W|BPF_IND jt=00 jf=00 k=0000000c
(0039) code= BPF_ALU|BPF_AND|BPF_K jt=00 jf=00 k=ffffffff
(003a) code= BPF_JMP|BPF_JEQ|BPF_K jt=00 jf=03 k=00000000
[ this above compares third 4 bytes with 00000000, if comparison fails
it jumps to 003e ]
(003b) code= BPF_LD|BPF_W|BPF_IND jt=00 jf=00 k=00000010
(003c) code= BPF_ALU|BPF_AND|BPF_K jt=00 jf=00 k=ffffffff
(003d) code= BPF_JMP|BPF_JEQ|BPF_K jt=01 jf=00 k=00000000
[ this above compares last 4 bytes with 00000000, if comparison succeded
it jumps to 003f, which means, accept event ]
(003e) code= BPF_RET|BPF_K jt=00 jf=00 k=00000000
---- final verdict ----
(003f) code= BPF_RET|BPF_K jt=00 jf=00 k=ffffffff
Just for the record: This chunk below shows the BPF code to filter IPv6
address 2:4:6:: {0x00020004, 0x00060000, 0x0, 0x0 } in case that
NFCT_FILTER_LOGIC_NEGATIVE is used, ie. if that address matches, drop
the event.
[...]
(0032) code= BPF_LD|BPF_W|BPF_IND jt=00 jf=00 k=00000004
(0033) code= BPF_ALU|BPF_AND|BPF_K jt=00 jf=00 k=ffffffff
(0034) code= BPF_JMP|BPF_JEQ|BPF_K jt=00 jf=09 k=00020004
[ this above compares first 4 bytes with 00020004, if comparison fails
it jumps to 003e ]
(0035) code= BPF_LD|BPF_W|BPF_IND jt=00 jf=00 k=00000008
(0036) code= BPF_ALU|BPF_AND|BPF_K jt=00 jf=00 k=ffffffff
(0037) code= BPF_JMP|BPF_JEQ|BPF_K jt=00 jf=06 k=00060000
[ this above compares second 4 bytes with 00060000, if comparison fails
it jumps to 003e ]
(0038) code= BPF_LD|BPF_W|BPF_IND jt=00 jf=00 k=0000000c
(0039) code= BPF_ALU|BPF_AND|BPF_K jt=00 jf=00 k=ffffffff
(003a) code= BPF_JMP|BPF_JEQ|BPF_K jt=00 jf=03 k=00000000
[ this above compares third 4 bytes with 00000000, if comparison fails
it jumps to 003e ]
(003b) code= BPF_LD|BPF_W|BPF_IND jt=00 jf=00 k=00000010
(003c) code= BPF_ALU|BPF_AND|BPF_K jt=00 jf=00 k=ffffffff
(003d) code= BPF_JMP|BPF_JEQ|BPF_K jt=01 jf=00 k=00000000
[ this above compares last 4 bytes with 00000000, if comparison succeded
it jumps to 003e ]
(003e) code= BPF_JMP|BPF_JA jt=00 jf=00 k=00000001
(003f) code= BPF_RET|BPF_K jt=00 jf=00 k=00000000
[ default action specified by 003e is to drop the event ]
Tested-by: Eric Leblond <eric@regit.org>
Reported-by: Eric Leblond <eric@regit.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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BPF code generated for IPv6 filtering was wrong.
Assuming you want to allow all traffic except ::1, the filter that
libnetfilter_conntrack generates for the IPv6 address part looks like:
[...]
(0032) code= BPF_LD|BPF_W|BPF_IND jt=00 jf=00 k=00000004
(0033) code= BPF_ALU|BPF_AND|BPF_K jt=00 jf=00 k=ffffffff
(0034) code= BPF_JMP|BPF_JEQ|BPF_K jt=00 jf=0a k=00000000
(0035) code= BPF_LD|BPF_W|BPF_IND jt=00 jf=00 k=00000008 [0]
(0036) code= BPF_ALU|BPF_AND|BPF_K jt=00 jf=00 k=ffffffff [1]
(0037) code= BPF_JMP|BPF_JEQ|BPF_K jt=00 jf=07 k=00000000 [2]
(0038) code= BPF_LD|BPF_W|BPF_IND jt=00 jf=00 k=0000000c [3]
(0039) code= BPF_ALU|BPF_AND|BPF_K jt=00 jf=00 k=ffffffff [4]
(003a) code= BPF_JMP|BPF_JEQ|BPF_K jt=00 jf=04 k=00000000 [5]
(003b) code= BPF_LD|BPF_W|BPF_IND jt=00 jf=00 k=00000010 [6]
(003c) code= BPF_ALU|BPF_AND|BPF_K jt=00 jf=00 k=ffffffff [7]
(003d) code= BPF_JMP|BPF_JEQ|BPF_K jt=01 jf=00 k=00000001 [8]
(003e) code= BPF_JMP|BPF_JA jt=00 jf=00 k=00000001 [9]
(003f) code= BPF_RET|BPF_K jt=00 jf=00 k=00000000 [A]
Line 32 loads the first 4 bytes for the 32 bytes IPv6 address, then
line 33 performs the binary AND with the first 4 bytes of the mask.
Line 34 evaluated false for the case 2::1 that Eric reported (since 0x2
is not 0x0). Thus, jumping to line 3f that returns reject. However,
2::1 should be allowed.
This false-jump case depends on the logic we're using, for the negative
logic case, the jump offset is 9 to accept it. In the positive case
(ie. accept this event message if matching happens), it has to be 10 (A),
to reject it.
Reported-by: Eric Leblond <eric@regit.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds more verbose output for the automatic BPF filter
generation to sieve netlink messages that are receive via
ctnetlink.
This code is disabled by default, only useful for debugging so
far. It shouldn't be hard to provide a function to explicitly
print instead.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch is *not* changing the licensing terms of this library (which
was initially released under GPLv2 and later on extended to GPLv2+ after
contacting all the contributors who kindly agreed to extend it to any
later GPL version).
Jan says: "In libnetfilter_conntrack, there are many .c files declaring
GNU GPL incorporated herein by reference without telling which version(s)
exactly apply. Given src/main.c for example is actually GPL-2.0+,
the reference made is ambiguous."
This patch should definitely clarify this.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
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This patch re-works the callback handling to allow the use the same socket
to send/receive commands and listen to events of both conntrack and
expectation subsystems. Now you can register one callback for conntrack
and one for expectation with the same handler with no problems (before
this patch, this was not possible, you required two different handlers).
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch fixes kernel-space filtering via BSF for several
network addresses. The problem is that we store the network
address of the netlink message in the ALU. Then, we perform
an AND of the network mask and the address, this operation
is stored again in the ALU. If we compare the address with
a second address, we have to reload the address to the ALU.
The following example clarifies the problem, in the following
order, we want to filter:
1) 224.0.0.0/4
2) 127.0.0.1/32
Now, we receive traffic from 127.0.0.1, it should be filtered.
However, without this patch, it is not. Let's see why:
ALU 7f000001 (addr=127.0.0.1)
AND f0000000 (cidr=4)
-------------------------------
ALU 70000000
this is stored in the ALU. Then, we check for 127.0.0.1:
ALU 70000000 (addr=127.0.0.1) <-- it should be 7f000001
AND ffffffff (cidr=32)
-------------------------------
ALU 70000000
This does not match 7f000001. To fix this, we have to reload
7f000001 to the ALU. Thus, the second comparison works fine.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds support to auto-generate BSF code for IPv6. It
requires a Linux kernel >= 2.6.29. The maximum number of addresses
is limited to 20 (12 BSF lines per IPv6 address comparison). I am
not sure that to remove this limit is useful given that oprofile
does not show very good numbers for very large (in terms of lines)
filters. This completes one feature that is available in IPv4 but
that was missing in IPv6.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch removes unnecessary function inlining in the BSF code
generation. There is not reason to get any significant performance
improvement in an operation that should be done in the
initialization path.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch reworks the BSF automatic generation code. This
feature needs more love and it has several limitations like
that the maximum number of IPs are 127 due to BSF code
restrictions. See this patch as a first step forward.
This patch also adds the stack data type, which is used to
resolve jump dynamically instead of the previous static
approach.
This patch also includes fixes in the limitations, previous
calculations were wrong.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch cleanups the internal headers by splitting them into several
logical pieces.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch introduces nfct_filter_set_logic() to set the filtering
logic which results in a more flexible solution.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds an abstraction level to berkeley sockets filter (BSF) for
Netlink sockets available since Linux kernel 2.6.26. This provides an
easy way to attach filters without knowing about BSF at all.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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