lib/ts_bm: add helper to reduce indentation and improve readability

The flow-control of `bm_find` is very deeply nested with a conditional
comparing a ternary expression against the pattern inside a for-loop
inside a while-loop inside a for-loop.

Move the inner for-loop into a helper function to reduce the amount of
indentation and make the code easier to read.

Fix indentation and trailing white-space in preceding debug logging
statement.

Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Florian Westphal <fw@strlen.de>

lib/ts_bm: reset initial match offset for every block of text

The `shift` variable which indicates the offset in the string at which
to start matching the pattern is initialized to `bm->patlen - 1`, but it
is not reset when a new block is retrieved. This means the implemen-
tation may start looking at later and later positions in each successive
block and miss occurrences of the pattern at the beginning. E.g.,
consider a HTTP packet held in a non-linear skb, where the HTTP request
line occurs in the second block:

[... 52 bytes of packet headers ...]
GET /bmtest HTTP/1.1\r\nHost: www.example.com\r\n\r\n

and the pattern is "GET /bmtest".

Once the first block comprising the packet headers has been examined,
`shift` will be pointing to somewhere near the end of the block, and so
when the second block is examined the request line at the beginning will
be missed.

Reinitialize the variable for each new block.

Fixes: 8082e4ed0a61 ("[LIB]: Boyer-Moore extension for textsearch infrastructure strike #2")
Link: https://bugzilla.netfilter.org/show_bug.cgi?id=1390
Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

lib/ts_bm.c: remove redundant store to variable consumed after addition

There is no need to store the result of the addition back to variable
consumed after the addition. The store is redundant, replace += with just
+

Cleans up clang scan build warning: lib/ts_bm.c:83:11: warning: Although
the value stored to 'consumed' is used in the enclosing expression, the
value is never actually read from 'consumed' [deadcode.DeadStores]

Link: https://lkml.kernel.org/r/20220704215325.600993-1-colin.i.king@gmail.com
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib/: replace HTTP links with HTTPS ones

Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.

Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Coly Li <colyli@suse.de> [crc64.c]
Link: http://lkml.kernel.org/r/20200726112154.16510-1-grandmaster@al2klimov.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/ts_bm.c: replace zero-length array with flexible-array member

The current codebase makes use of the zero-length array language extension
to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
int stuff;
struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning in
case the flexible array does not occur last in the structure, which will
help us prevent some kind of undefined behavior bugs from being
inadvertenly introduced[3] to the codebase from now on.

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200211205620.GA24694@embeddedor
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

textsearch: ts_bm: support case insensitive searching in Boyer-Moore algorithm

Add support for case insensitive search to Boyer-Moore algorithm.

Signed-off-by: Joonwoo Park <joonwpark81@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

textsearch: fix Boyer-Moore text search bug

The current logic has a bug which cannot find matching pattern, if the
pattern is matched from the first character of target string.
for example:
pattern=abc, string=abcdefg
pattern=a, string=abcdefg
Searching algorithm should return 0 for those things.

Signed-off-by: Joonwoo Park <joonwpark81@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[TEXTSEARCH]: Fix Boyer Moore initialization bug

The pattern is set after trying to compute the prefix table, which tries
to use it. Initialize it before calling compute_prefix_tbl, make
compute_prefix_tbl consistently use only the data from struct ts_bm
and remove the now unnecessary arguments.

Signed-off-by: Michael Rash <mbr@cipherdyne.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

Remove obsolete #include <linux/config.h>

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

[TEXTSEARCH]: Fix broken good shift array calculation in Boyer-Moore

The current logic does not calculate correctly the good shift array:
Let x be the pattern that is being searched. Let y be the block of data.
The good shift array aligns the segment:

x[i+1 ... m-1] = y[i+j+1 ... j+m-1]

with its rightmost occurrence in x that fulfils x[i] neq y[i+j].

In previous version, the good shift array for the pattern ANPANMAN is:
[1, 8, 3, 8, 8, 8, 8, 8]
and should be:
[1, 8, 3, 6, 6, 6, 6, 6]

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

[PATCH] gfp flags annotations - part 1

- added typedef unsigned int __nocast gfp_t;

- replaced __nocast uses for gfp flags with gfp_t - it gives exactly
the same warnings as far as sparse is concerned, doesn't change
generated code (from gcc point of view we replaced unsigned int with
typedef) and documents what's going on far better.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[TEXTSEARCH]: fix sparse gfp nocast warnings

Fix nocast sparse warnings:
include/linux/textsearch.h:165:57: warning: implicit cast to nocast type

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

[LIB]: Boyer-Moore extension for textsearch infrastructure strike #2

Attached the implementation of the Boyer-Moore string search
algorithm for the new textsearch infrastructure.

I've added as well a note about the limitations that this approach
presents, as Thomas has remarked.

Signed-off-by: Pablo Neira Ayuso <pablo@eurodev.net>
Signed-off-by: David S. Miller <davem@davemloft.net>