So far, the patterns as passed to the mpm's would use global id's that
were shared among all buffers, directions. This would lead to a fairly
large pattern id space. As the mpm algo's use the pattern id's to
prevent duplicate matching through a pattern id based bitarray,
shrinking this space will optimize performance.
This patch implements this. It sets a flag before adding the pattern
to the mpm ctx, instructing the mpm to ignore the provided pid and
handle pids management itself. This leads to a shrinking of the
bitarray size.
This is made possible by the previous work that removes the pid logic
from the code.
Next to this, this patch moves the pattern setup stage to common util
functions. This avoids code duplication.
Update ac, ac-bs and ac-ks to use this.
Rather than creating the array of size maxpatid, dynamically resize as needed.
This also handles the case where duplicate pid are added to the array.
Also fix error in bitarray allocation (local version) to always use bitarray_size.
Rather than statically allocate 64K entries in every rule_id_array,
increase the size only when needed. Created a new function MpmAddSids()
to check the size before adding the new sids. If the array is not large
enough, it calls MpmAddSidsResize() that calls realloc and does error
checking. If the realloc fails, it prints an error and drops the new sids
on the floor, which seems better than exiting Suricata.
The size is increased to (current_size + new_count) * 2. This handles the
case where new_count > current_size, which would not be handled by simply
using current_size * 2. It should also be faster than simply reallocing to
current_size + new_count, which would then require another realloc for each
new addition.
Remove local copies from each MPM file and use include file instead.
Might be better to also add util-memcpy.c rather than inlining it each time,
to get smaller code, since only seems to be used at initialization.
The case_state in MPMs was just to track when a pid could have no-case and
case-sensitive matches for the same PID. Now that can't happen after fixing
bug 1110, so remove the code and storage for case_state.
This fixes bug 1110. When assigning PIDs, use the NO_CASE flag when comparing
for duplicates. The state of the flag must be the same, but also use the same
type of comparisons when checking for duplicates.
Previously, "foo":CS would match with "foo":CI when it should not.
and "foo":CI would not match "FoO":CI when it should. Both of those
cases are fixed with this change.
This then allows simplifying the use of pid in MPMs because now if they
pids match, then so do the flags, so checking the flags is not required.
app-layer.[ch], app-layer-detect-proto.[ch] and app-layer-parser.[ch].
Things addressed in this commit:
- Brings out a proper separation between protocol detection phase and the
parser phase.
- The dns app layer now is registered such that we don't use "dnstcp" and
"dnsudp" in the rules. A user who previously wrote a rule like this -
"alert dnstcp....." or
"alert dnsudp....."
would now have to use,
alert dns (ipproto:tcp;) or
alert udp (app-layer-protocol:dns;) or
alert ip (ipproto:udp; app-layer-protocol:dns;)
The same rules extend to other another such protocol, dcerpc.
- The app layer parser api now takes in the ipproto while registering
callbacks.
- The app inspection/detection engine also takes an ipproto.
- All app layer parser functions now take direction as STREAM_TOSERVER or
STREAM_TOCLIENT, as opposed to 0 or 1, which was taken by some of the
functions.
- FlowInitialize() and FlowRecycle() now resets proto to 0. This is
needed by unittests, which would try to clean the flow, and that would
call the api, AppLayerParserCleanupParserState(), which would try to
clean the app state, but the app layer now needs an ipproto to figure
out which api to internally call to clean the state, and if the ipproto
is 0, it would return without trying to clean the state.
- A lot of unittests are now updated where if they are using a flow and
they need to use the app layer, we would set a flow ipproto.
- The "app-layer" section in the yaml conf has also been updated as well.
Content strings that are a duplicate of a pattern from another sig, but
have a fast_pattern chop being applied, would end up being assigned the
same pattern id as the duplicate string. But the string supplied to the
mpm would be the chopped string, which might result in the state_table
output_state content entry being over-riden by the the fuller string at
the final state of the smaller content length, because of which during a
match we might end up inspecting the search buffer against the fuller
content pattern, instead of the chopped pattern, which would end up being
an inspection beyond the buffer bounds.
When handling error case on SCMallog, SCCalloc or SCStrdup
we are in an unlikely case. This patch adds the unlikely()
expression to indicate this to gcc.
This patch has been obtained via coccinelle. The transformation
is the following:
@istested@
identifier x;
statement S1;
identifier func =~ "(SCMalloc|SCStrdup|SCCalloc)";
@@
x = func(...)
... when != x
- if (x == NULL) S1
+ if (unlikely(x == NULL)) S1
Jason Ish
Victor Julien
Ken Steele
Anoop Saldanha
Eric Leblond
Anoop Saldanha
Eileen Donlon