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Gcc is currenlty not in the ability to optimize the switch statement in
sk_run_filter() because of dense case labels. This patch replace the
OR'd labels with ordered sequenced case labels. The sk_chk_filter()
function is modified to patch/replace the original OPCODES in a
ordered but equivalent form. gcc is now in the ability to transform the
switch statement in sk_run_filter into a jump table of complexity O(1).
Until this patch gcc generates a sequence of conditional branches (O(n) of 567
byte .text segment size (arch x86_64):
7ff: 8b 06 mov (%rsi),%eax
801: 66 83 f8 35 cmp $0x35,%ax
805: 0f 84 d0 02 00 00 je adb <sk_run_filter+0x31d>
80b: 0f 87 07 01 00 00 ja 918 <sk_run_filter+0x15a>
811: 66 83 f8 15 cmp $0x15,%ax
815: 0f 84 c5 02 00 00 je ae0 <sk_run_filter+0x322>
81b: 77 73 ja 890 <sk_run_filter+0xd2>
81d: 66 83 f8 04 cmp $0x4,%ax
821: 0f 84 17 02 00 00 je a3e <sk_run_filter+0x280>
827: 77 29 ja 852 <sk_run_filter+0x94>
829: 66 83 f8 01 cmp $0x1,%ax
[...]
With the modification the compiler translate the switch statement into
the following jump table fragment:
7ff: 66 83 3e 2c cmpw $0x2c,(%rsi)
803: 0f 87 1f 02 00 00 ja a28 <sk_run_filter+0x26a>
809: 0f b7 06 movzwl (%rsi),%eax
80c: ff 24 c5 00 00 00 00 jmpq *0x0(,%rax,8)
813: 44 89 e3 mov %r12d,%ebx
816: e9 43 03 00 00 jmpq b5e <sk_run_filter+0x3a0>
81b: 41 89 dc mov %ebx,%r12d
81e: e9 3b 03 00 00 jmpq b5e <sk_run_filter+0x3a0>
Furthermore, I reordered the instructions to reduce cache line misses by
order the most common instruction to the start.
Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Add an SKF_AD_HATYPE field to the packet ancilliary data area, giving
access to skb->dev->type, as reported in the sll_hatype field.
When capturing packets on a PF_PACKET/SOCK_RAW socket bound to all
interfaces, there doesn't appear to be a way for the filter program to
actually find out the underlying hardware type the packet was captured
on. This patch adds such ability.
This patch also handles the case where skb->dev can be NULL, such as on
netlink sockets.
Signed-off-by: Paul Evans <leonerd@leonerd.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This cleanup patch puts struct/union/enum opening braces,
in first line to ease grep games.
struct something
{
becomes :
struct something {
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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It can help being able to filter packets on their queue_mapping.
If filter performance is not good, we could add a "numqueue" field
in struct packet_type, so that netif_nit_deliver() and other functions
can directly ignore packets with not expected queue number.
Lets experiment this simple filter extension first.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Allow bpf to set a filter to drop packets that dont
match a specific mark
Signed-off-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>
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SKF_AD_NLATTR allows us to find the first matching attribute in a
stream of netlink attributes from one offset to the end of the
netlink message. This is not suitable to look for a specific
matching inside a set of nested attributes.
For example, in ctnetlink messages, if we look for the CTA_V6_SRC
attribute in a message that talks about an IPv4 connection,
SKF_AD_NLATTR returns the offset of CTA_STATUS which has the same
value of CTA_V6_SRC but outside the nest. To differenciate
CTA_STATUS and CTA_V6_SRC, we would have to make assumptions on the
size of the attribute and the usual offset, resulting in horrible
BSF code.
This patch adds SKF_AD_NLATTR_NEST, which is a variant of
SKF_AD_NLATTR, that looks for an attribute inside the limits of
a nested attributes, but not further.
This patch validates that we have enough room to look for the
nested attributes - based on a suggestion from Patrick McHardy.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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SKF_ADF_NLATTR searches for a netlink attribute, which avoids manually
parsing and walking attributes. It takes the offset at which to start
searching in the 'A' register and the attribute type in the 'X' register
and returns the offset in the 'A' register. When the attribute is not
found it returns zero.
A top-level attribute can be located using a filter like this
(example for nfnetlink, using struct nfgenmsg):
...
{
/* A = offset of first attribute */
.code = BPF_LD | BPF_IMM,
.k = sizeof(struct nlmsghdr) + sizeof(struct nfgenmsg)
},
{
/* X = CTA_PROTOINFO */
.code = BPF_LDX | BPF_IMM,
.k = CTA_PROTOINFO,
},
{
/* A = netlink attribute offset */
.code = BPF_LD | BPF_B | BPF_ABS,
.k = SKF_AD_OFF + SKF_AD_NLATTR
},
{
/* Exit if not found */
.code = BPF_JMP | BPF_JEQ | BPF_K,
.k = 0,
.jt = <error>
},
...
A nested attribute below the CTA_PROTOINFO attribute would then
be parsed like this:
...
{
/* A += sizeof(struct nlattr) */
.code = BPF_ALU | BPF_ADD | BPF_K,
.k = sizeof(struct nlattr),
},
{
/* X = CTA_PROTOINFO_TCP */
.code = BPF_LDX | BPF_IMM,
.k = CTA_PROTOINFO_TCP,
},
{
/* A = netlink attribute offset */
.code = BPF_LD | BPF_B | BPF_ABS,
.k = SKF_AD_OFF + SKF_AD_NLATTR
},
...
The data of an attribute can be loaded into 'A' like this:
...
{
/* X = A (attribute offset) */
.code = BPF_MISC | BPF_TAX,
},
{
/* A = skb->data[X + k] */
.code = BPF_LD | BPF_B | BPF_IND,
.k = sizeof(struct nlattr),
},
...
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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The sk_filter function is too big to be inlined. This saves 2296 bytes
of text on allyesconfig.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Some minor style cleanups:
* Move __KERNEL__ definitions to one place in filter.h
* Use const for sk_filter_len
* Line wrapping
* Put EXPORT_SYMBOL next to function definition
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Filter is attached in a separate function, so do the
same for filter detaching.
This also removes one variable sock_setsockopt().
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Function sk_filter() is called from tcp_v{4,6}_rcv() functions with arg
needlock = 0, while socket is not locked at that moment. In order to avoid
this and similar issues in the future, use rcu for sk->sk_filter field read
protection.
Signed-off-by: Dmitry Mishin <dim@openvz.org>
Signed-off-by: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Signed-off-by: Kirill Korotaev <dev@openvz.org>
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It should return an unsigned value, and fix sk_filter() as well.
Signed-off-by: Kris Katterjohn <kjak@ispwest.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
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Hagen Paul Pfeifer
Paul LeoNerd Evans
Eric Dumazet
jamal
Pablo Neira Ayuso
Patrick McHardy
Stephen Hemminger
Pavel Emelyanov
Dmitry Mishin
Kris Katterjohn
Linus Torvalds