Simplify statements where there's a conditional statement followed by
return true or return false.
Instead of
if (conditional)
return true;
else
return false;
Use:
return conditional
When in a `base64_decode`-`base64_data` pair the decode was depending
on another match through the relative option, the `buffer_offset` would
be updated to the relative position of the previous match. During the
`base64_data` phase, a relative match would use that offset even though
the match happened in a new buffer.
Example::
http.request_body; content:"|27|"; \
base64_decode:relative; \
base64_data; content:"|ff ff ff ff|"; within:16;
This use of the `buffer_offset` is incorrect as that value is relative
to a buffer and the `base64_data` points to a new buffer.
This patch addresses this by resetting DetectEngineThreadCtx::buffer_offset
before inspecting `base64_data`.
Bug: #7842.
Issue: 7549
Use the active buffer list to fetch SM variables to ensure that they are
part of the same list so a variable created with bytemath or byteextract
will have context when used with bytejump, e.g
Not needed for content modifiers.
Under some cases (below), the depth and offset values are used
twice. This commit disregards the distance variable (if any), when
computing the final depth.
These rules are logically equivalent::
1. alert tcp any any -> any 8080 (msg:"distance name"; flow:to_server; content:"Authorization:"; content:"5f71ycy"; distance:0; byte_extract:1,0,option_len,string,relative; content:!"|38|"; distance:option_len; within:1; content:"|37|"; distance:-1; within:1; content:"|49|"; distance:option_len; within:1; sid:1;)
2. alert tcp any any -> any 8080 (msg:"distance number"; flow:to_server; content:"Authorization:"; content:"5f71ycy"; distance:0; byte_extract:1,0,option_len,string,relative; content:!"|38|"; distance:7; within:1; content:"|37|"; distance:-1; within:1; content:"|49|"; distance:option_len; within:1; sid:2;)
The differences:
Rule 1: content:!"|38|"; distance:option_len; within:1; //option_len == 7
Rule 2: content:!"|38|"; distance:7; within:1;
Without this commit, rule 2 triggers an alert but rule 1 doesn't.
Issue: 7390
Ticket: 7526
The usage of negated pcre, followed by other relative payload
content keywords could lead to an infinite loop.
This is because regular (not negated) pcre can test multiple
occurences, but negated pcre should be tried only once.
This commit removes the `_AL_` usage in detect keywords for improved
readability.
Some of the HTTP rule keywords already had counterparts without using
"_AL_". These rule keywords are the legacy content modifier keywords
that now have sticky buffer equivalents.
For these, "_AL_" was removed and a suffix was added to the #define:
src/detect-engine-register.h:151: DETECT_HTTP_COOKIE_CM
src/detect-engine-register.h:153: DETECT_HTTP_METHOD_CM
src/detect-engine-register.h:161: DETECT_HTTP_HEADER_CM
src/detect-engine-register.h:173: DETECT_HTTP_RAW_HEADER_CM
src/detect-engine-register.h:175: DETECT_HTTP_URI_CM
src/detect-engine-register.h:179: DETECT_HTTP_STAT_MSG_CM
src/detect-engine-register.h:181: DETECT_HTTP_STAT_CODE_CM
src/detect-engine-register.h:185: DETECT_HTTP_HOST_CM
Ticket: 2224
It takes an argument to match only if the buffer is absent,
or it can still match if the buffer is present, but we test
the absence of some content.
For multi buffers, absent matches if there are 0 buffers.
For file keywords, absent matches if there is no file.
To avoid future problems with overlapping flag values, give bytejump
its own DETECT_BYTEJUMP_OFFSET_VAR flag.
The values are currently not overlapping, so this patch should have
no side effects.
Since recursive content matching goes through the buffer from left to
right, it is possible to bail early when isdataat is part of the
recursive checking. If `isdataat:50,relative` fails for offset 10, it
will surely also fail for offset 20. So break inspection in such cases.
The exception is for dynamic isdataat, where the value is determined
by a prior byte_extract that may be updated during the recursion.
Use stack local var instead of DetectEngineThreadCtx member. Instead
setup a stack local struct that both counts and holds the limit. Make sure
the limit is a const so we can avoid rereading it.
This is part of an effort to reduce the size of the DetectEngineThreadCtx
structure and reduce the number of memory writes to it. Additionally, it
is part of an effect to reduce the number of places where detection
tracks various forms of state.
Since the asn1 keyword is processing payload data, move the handling of
the keyword into the PMATCH with content inspection.
Use u32 as buffer length in the Rust FFI
Previously various steps in the content inspection logic would use
a variable in the DetectEngineThreadCtx to flag that matching should
be discontinued.
This patch reimplements this logic by using a new return code instead.
Split content inspection into public and private version, so that
common initialization can be done in a single place.
Update the callsites.
Issue: 6144
This commit allows the byte_test keyword to accept an existing
variable name for a value (the value may still be specified directly as
an integer).
All nbytes values are subject to the same value constraints as before
- 23 if included with string
- 8 otherwise
Issue: 5077
This commit
- Converts the PCRE based parser to Rust.
- Adds unit tests to the new Rust modules
- Removes the PCRE parser from detect-bytemath.c
- Adjusts the C source modules to refer to the Rust definitions
- Includes the multiply operator (missing from the C parser)
Rearrange code slightly to make it more clear that `found` cannot
be NULL further down the loop.
cppcheck:
src/detect-engine-content-inspection.c:316:50: warning: Either the condition 'found!=NULL' is redundant or there is overflow in pointer subtraction. [nullPointerArithmeticRedundantCheck]
match_offset = (uint32_t)((found - buffer) + cd->content_len);
^
src/detect-engine-content-inspection.c:308:30: note: Assuming that condition 'found!=NULL' is not redundant
} else if (found != NULL && (cd->flags & DETECT_CONTENT_NEGATED)) {
^
src/detect-engine-content-inspection.c:316:50: note: Null pointer subtraction
match_offset = (uint32_t)((found - buffer) + cd->content_len);
^
Bug: #5291.
Philippe Antoine
Jeff Lucovsky
Victor Julien
Jason Ish
Philippe Antoine