Match on server name indication (SNI) extension in TLS using tls_sni
keyword, e.g:
alert tls any any -> any any (msg:"SNI test"; tls_sni;
content:"example.com"; sid:12345;)
*** CID 1358124: Null pointer dereferences (REVERSE_INULL)
/src/detect-engine-mpm.c: 940 in MpmStoreSetup()
934 PopulateMpmHelperAddPatternToPktCtx(ms->mpm_ctx,
935 cd, s, 0, (cd->flags & DETECT_CONTENT_FAST_PATTERN_CHOP));
936 }
937 }
938 }
939
>>> CID 1358124: Null pointer dereferences (REVERSE_INULL)
>>> Null-checking "ms->mpm_ctx" suggests that it may be null, but it has already been dereferenced on all paths leading to the check.
940 if (ms->mpm_ctx != NULL) {
941 if (ms->mpm_ctx->pattern_cnt == 0) {
942 MpmFactoryReClaimMpmCtx(de_ctx, ms->mpm_ctx);
943 ms->mpm_ctx = NULL;
944 } else {
945 if (ms->sgh_mpm_context == MPM_CTX_FACTORY_UNIQUE_CONTEXT) {
SGH's for tcp and udp are now always only per proto and per direction.
This means we can simply reuse the packet and stream mpm pointers.
The SGH's for the other protocols already used a directionless catch
all mpm pointer.
Turn list of mpm_ctx pointers into a union so that we don't waste
space. The sgh's for tcp and udp are in one direction only, so the
ts and tc ones are now in the union.
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.
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 TCP packet could not get a flow (flow engine out of flows/memory)
and there were *only* TCP inspecting rules with the direction
explicitly set to 'to_server', a NULL pointer deref could happen.
PacketPatternSearchWithStreamCtx would fall through to the 'to_client'
case which was not initialized.
This commit do a find and replace of the following:
- DETECT_SM_LIST_HSBDMATCH by DETECT_SM_LIST_FILEDATA
sed -i 's/DETECT_SM_LIST_HSBDMATCH/DETECT_SM_LIST_FILEDATA/g' src/*
- HSBD by FILEDATA:
sed -i 's/HSBDMATCH/FILEDATA/g' src/*
The minimal detect engine has only the minimal memory use and setup
time. It's to be used for 'delayed' detect where the first detection
engine is essentially empty.
The threads setup are also minimal.
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.
This is required because SCMemcmpLowercase() expects it first argument
to be already lowercase for the comparison. This is done by using
memcpy_tolower() for NO_CASE patterns.
This addresses code review comments from Victor.
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.
This patch is a result of applying the following coccinelle
transformation to suricata sources:
@istested@
identifier x;
statement S1;
identifier func =~ "(SCMalloc|SCStrdup|SCCalloc|SCMallocAligned|SCRealloc)";
@@
x = func(...)
... when != x
- if (x == NULL) S1
+ if (unlikely(x == NULL)) S1
Aho-Corasick mpm optimized for Tilera Tile-Gx architecture. Based on the
util-mpm-ac.c code base. The primary optimizations are:
1) Matching function used Tilera specific instructions.
2) Alphabet compression to reduce delta table size to increase cache
utilization and performance.
The basic observation is that not all 256 ASCII characters are used by
the set of multiple patterns in a group for which a DFA is
created. The first reason is that Suricata's pattern matching is
case-insensitive, so all uppercase characters are converted to
lowercase, leaving a hole of 26 characters in the
alphabet. Previously, this hole was simply left in the middle of the
alphabet and thus in the generated Next State (delta) tables.
A new, smaller, alphabet is created using a translation table of 256
bytes per mpm group. Previously, there was one global translation
table for converting upper case to lowercase.
Additional, unused characters are found by creating a histogram of all
the characters in all the patterns. Then all the characters with zero
counts are mapped to one character (0) in the new alphabet. Since
These characters appear in no pattern, they can all be mapped to a
single character and still result in the same matches being
found. Zero was chosen for the value in the new alphabet since this
"character" is more likely to appear in the input. The unused
character always results in the next state being state zero, but that
fact is not currently used by the code, since special casing takes
additional instructions.
The characters that do appear in some pattern are mapped to
consecutive characters in the new alphabet, starting at 1. This
results in a dense packing of next state values in the delta tables
and additionally can allow for a smaller number of columns in that
table, thus using less memory and better packing into the cache. The
size of the new alphabet is the number of used characters plus 1 for
the unused catch-all character.
The alphabet size is rounded up to the next larger power-of-2 so that
multiplication by the alphabet size can be done with a shift. It
might be possible to use a multiply instruction, so that the exact
alphabet size could be used, which would further reduce the size of
the delta tables, increase cache density and not require the
specialized search functions. The multiply would likely add 1 cycle to
the inner search loop.
Since the multiply by alphabet-size is cleverly merged with a mask
instruction (in the SINDEX macro), specialized versions of the
SCACSearch function are generated for alphabet sizes 256, 128, 64, 32
and 16. This is done by including the file util-mpm-ac-small.c
multiple times with a redefined SINDEX macro. A function pointer is
then stored in the mpm context for the search function. For alpha bit
sizes of 8 or smaller, the number of states usually small, so the DFA
is already very small, so there is little difference using the 16
state search function.
The SCACSearch function is also specialized by the size of the value
stored in the next state (delta) tables, either 16-bits or 32-bits.
This removes a conditional inside the Search function. That
conditional is only called once, but doesn't hurt to remove
it. 16-bits are used for up to 32K states, with the sign bit set for
states with matches.
Future optimization:
The state-has-match values is only needed per state, not per next
state, so checking the next-state sign bit could be replaced with
reading a different value, at the cost of an additional load, but
increasing the 16-bit next state span to 64K.
Since the order of the characters in the new alphabet doesn't matter,
the new alphabet could be sorted by the frequency of the characters in
the expected input stream for that multi-pattern matcher. This would
group more frequent characters into the same cache lines, thus
increasing the probability of reusing a cache-line.
All the next state values for each state live in their own set of
cache-lines. With power-of-two sizes alphabets, these don't overlap.
So either 32 or 16 character's next states are loaded in each cache
line load. If the alphabet size is not an exact power-of-2, then the
last cache-line is not completely full and up to 31*2 bytes of that
line could be wasted per state.
The next state table could be transposed, so that all the next states
for a specific character are stored sequentially, this could be better
if some characters, for example the unused character, are much more
frequent.
Rename struct DetectFigureFPAndId_t_ to DetectFPAndItsId_ and move it's
definition from inside the function where it's used to the global namespace,
as requested on #suricata.
Rename DetectEngineContentModifiedBufferSetup to DetectEngineContentModifierBufferSetup.
Also rename DetectFigureFPAndId() to DetectSetFastPatternAndItsId().
Updated DetectSetFastPatternAndItsId() to not exit on failure and return error.
All fp id assignment now happens in one go.
Also noticing a slight perf increase, probably emanating from improved cache
perf.
Removed irrelevant unittests as well.
Victor Julien
Mats Klepsland
Justin Viiret
maxtors
Giuseppe Longo
Ken Steele
Anoop Saldanha
Eric Leblond