Add startswith modifier to simplify matching patterns at the start
of a buffer.
Instead of:
content:"abc"; depth:3;
This enables:
content:"abc"; startswith;
Especially with longer patterns this makes the intention of the rule
more clear and eases writing the rules.
Internally it's simply a shorthand for 'depth:<pattern len>;'.
Ticket https://redmine.openinfosecfoundation.org/issues/742
Propagate inspection limits from anchered keywords to the rest of
a rule.
Examples:
content:"A"; depth:1; is anchored, it can only match in the first byte
content:"A"; depth:1; content:"BC"; distance:0; within:2;
"BC" can only be in the 2nd and 3rd byte of the payload. So effectively
it has an implicite offset of 1 and an implicit depth of 3.
content:"A"; depth:1; content:"BC"; distance:0; can assume offset:1; for
the 2nd content.
content:"A"; depth:1; pcre:"/B/R"; content:"C"; distance:0; can assume
at least offset:1; for content "C". We can't analyzer the pcre pattern
(yet), so we assume it matches with 0 bytes.
Add lots of test cases.
Rules can contain conflicting statements and lead to a unmatchable rule.
2 examples are rejected by this patch:
1. dsize < content
2. dsize < content@offset
Bug #2187
Set flags by default:
-Wmissing-prototypes
-Wmissing-declarations
-Wstrict-prototypes
-Wwrite-strings
-Wcast-align
-Wbad-function-cast
-Wformat-security
-Wno-format-nonliteral
-Wmissing-format-attribute
-funsigned-char
Fix minor compiler warnings for these new flags on gcc and clang.
In preparation of turning input to keyword parsers to const add
options to the common rule parser to enforce and strip double
quotes and parse negation support.
At registration, the keyword can register 3 extra flags:
SIGMATCH_QUOTES_MANDATORY: value to keyword must be quoted
SIGMATCH_QUOTES_OPTIONAL: value to keyword may be quoted
SIGMATCH_HANDLE_NEGATION: leading ! is parsed
In all cases leading spaces are removed. If the 'quote' flags are
set, the quotes are removed from the input as well.
The expression 'isdataat:!1,relative' is used to make sure a match
is at the end of a buffer quite often. This patch optimizes this case
for 'content' followed by the expression. It enforces it by setting
and 'ends with' flag on the content and then taking that flag into
account while doing the pattern match.
Content inspection optimization: when just distance is used without
within we don't need to search recursively.
E.g. content:"a"; content:"b"; distance:1; will scan the buffer for
'a' and when it finds 'a' it will scan the remainder for 'b'. Until
now, the failure to find 'b' would lead to looking for the next 'a'
and then for 'b' after that. However, we already inspected the
entire buffer for 'b', so we know this will fail.
This new API allows for different SPM implementations, using a function
pointer table like that used for MPM.
This change also switches over the paths that make use of
DetectContentData (which previously used BoyerMoore directly) to the new
API.
The idea is: if mpm is negated, it's both on mpm and nonmpm sid lists
and we can kick it out in that case during the merge sort.
It only works for patterns that are 'independent'. This means that the
rule doesn't need to only match if the negated mpm pattern is limited
to the first 10 bytes for example.
Or more generally, an negated mpm pattern that has depth, offset,
distance or within settings can't be handled this way. These patterns
are not added to the mpm at all, but just to to non-mpm list. This
makes sense as they will *always* need manual inspection.
Similarly, a pattern that is 'chopped' always needs validation. This
is because in this case we only inspect a part of the final pattern.
If a pattern has matched on mpm, don't re-inspect it later, subject to certain
conditions met by the pattern - namely, not negated, right chop, no replacet
attached to it.
The http_server_body content modifier modifies the previous content to inspect
the normalized (dechunked, unzipped) http_server_body. The workings are similar
to http_client_body. Additionally, a new pcre flag was introduced "/S".
To facilitate this change the signature flags field was changed to be 64 bit.
This patch adds support for the replace keyword. It is used with
content to change selected part of the payload. The major point
with this patch is that having a replace keyword made necessary
to avoid all stream level check because we need to access to the
could-be-modified packet payload.
One of the main difficulty is to handle complex signature. If there is
other content check, we must do the substitution when we're sure all
match are valid. The patch adds an attribute to the thread context
variable to be able to deal with recursivity of the match function.
Replace is only activated in IPS mode and apply only to raw match.
Victor Julien
Justin Viiret
Jason Ish
Anoop Saldanha
Last G
Anoop Saldanha
Eric Leblond
Gurvinder Singh
William Metcalf
Pablo Rincon