smb: New keyword smb.cmd v8

[zer1t0]

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Link to redmine ticket: https://redmine.openinfosecfoundation.org/issues/5069

Describe changes:

• New keyword smb.cmd added, which allows to match the command value in smb message header. It works for smb1 and smb2.
• Documentation for the keyword added (created SMB keyword documentation)

Example of rule alert smb any any -> any any (msg: "Smb command rule"; smb.cmd: 10; sid: 1;) . More examples in documentation.

suricata-verify-pr: 733

[codecov[bot]]

Codecov Report

Merging #7404 (688226c) into master (b6407c4) will decrease coverage by 0.13%. The diff coverage is 76.74%.

@@            Coverage Diff             @@
##           master    #7404      +/-   ##
==========================================
- Coverage   75.94%   75.80%   -0.14%     
==========================================
  Files         656      657       +1     
  Lines      189916   189956      +40     
==========================================
- Hits       144233   144004     -229     
- Misses      45683    45952     +269     

Flag	Coverage Δ
fuzzcorpus	60.29% <30.76%> (-0.35%)	:arrow_down:
suricata-verify	51.86% <82.50%> (-0.04%)	:arrow_down:
unittests	61.07% <33.33%> (+<0.01%)	:arrow_up:

Flags with carried forward coverage won't be shown. Click here to find out more.

[victorjulien]

One concern I have is around expectations of matching each record on the wire vs the "transaction" representation we have in Suricata, that are not necessarily a 1 on 1 mapping with records. So a rule writer will look at a pcap and then expect this keyword to match on each smb record, but it won't.

Maybe this would make more sense to use the new (and in development) frames API. This is designed to work on the record/frame level, w/o the higher level TX abstraction overhead. Currently you could do a smb.cmd frame, which would be for each record but currently won't offer the more elaborate keyword options. It would just be smb.cmd; content:"|00|";.

[victorjulien]

Closing due to inactivity. If you're interested in picking this back up, please open a new PR addressing the comments. Thanks!