IMAP protocol parser, logger and sticky buffers v9#15730
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This introduces a parser for IMAP protocol.
An IMAP transaction has two states driven by the 'complete' field:
- Open (complete = false): waiting for a matching tagged response.
- Complete (complete = true): tagged response received, or special
conditions met (BYE, server greeting).
Completion logic (is_complete):
- If a tagged request exists: requires a matching tagged response.
- No tagged request + BYE: complete (server closing).
- No tagged request + any response: complete (server greeting).
Transactions are created in three places:
1. Request parser: every parsed command creates a new tx.
2. Response parser (tagged, no matching request): midstream/async;
orphan tagged response gets its own tx.
3. Response parser (untagged, no incomplete tx): server greeting or
unsolicited response.
Once open, messages accumulate:
- Request side: continuation and literal data attach to the most
recent incomplete tx.
- Response side: untagged responses attach to the most recent
incomplete tx; tagged responses attach via find_request(tag).
Email extraction happens at most once per tx:
- From literal data in APPEND commands (request side).
- From FETCH response data (response side).
Seven hard limits prevent unbounded growth:
- IMAP_MAX_TX (256, configurable): total transactions. Exceeded:
all incomplete txs force-completed with TooManyTransactions event.
- IMAP_MAX_MSGS_PER_TX (512): requests/responses per tx. Exceeded:
message silently dropped.
- IMAP_MAX_LINES (512): request/response lines per tx. Exceeded:
line silently dropped.
- IMAP_MAX_BODY_SIZE (10MB): email body in ImapParsedEmail.
Exceeded: body truncated, BodyTooLarge event.
- IMAX_MAX_HEADERS (512): Numbers of headers parsed and stored. Exceeded:
TooManyHeaders event.
- IMAP_MAX_LINE_SIZE (8KB): request/response line max length. Exceeded:
LineTooLong event.
- Literal size (u32): bounded by declared size in {N} specifier.
IMAP_MAX_TX only is configurable limit via app-layer.protocols.imap.max-tx.
Ticket OISF#8276
This introduces a logger for IMAP protocol. Ticket OISF#8276
This implements the following sticky buffers for IMAP protocol: - imap.request - imap.response The following frames have been added: - imap.body - imap.headers - imap.pdu The following email sticky buffers have been updated to work with IMAP: - email.from - email.subject - email.to - email.cc - email.date - email.message_id - email.x_mailer The following email sticky buffers have been added and are supported only for IMAP: - email.command - email.body - email.header - email.header.name - email.header.value Ticket OISF#8276
glongo
requested review from
a team,
jasonish,
jufajardini and
victorjulien
as code owners
Codecov Report❌ Patch coverage is Additional details and impacted files@@ Coverage Diff @@
## main #15730 +/- ##
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Coverage 82.96% 82.97%
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Files 1003 1006 +3
Lines 275031 277647 +2616
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+ Hits 228192 230366 +2174
- Misses 46839 47281 +442
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| suricata.yaml is now 1 MiB instead of 0/unlimited. | ||
| - LLMNR protocol parser, logger and sticky buffers are implemented. | ||
| - IMAP protocol parser is enabled by default. | ||
| - IMAP logger and sticky buffers are implemented. |
Member
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this is not a changelog, only important changes to existing deployments should be mentioned
| #[derive(Default, Debug)] | ||
| pub struct ImapTransaction { | ||
| pub tx_id: u64, | ||
| pub complete: bool, |
Member
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we'll need a per direction tx state (progress) tracking. A Tx can be complete in one direction, but not the other. We need this for the firewall work. In the simplest form this would be complete_ts, complete_tc. It needs to be real time too, so ts can't wait for tc.
| }; | ||
| let _ = helper_keyword_register_multi_buffer(&kw); | ||
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| G_IMAP_REQUEST_BUFFER_ID = SCDetectHelperMultiBufferMpmRegister( |
Member
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these are registered at progress 0, but it's unclear if that is the correct time. See also the required progress tracking update mention elsewhere in the PR.
| LiteralInfo, IMAP_MAX_BODY_SIZE, IMAP_MAX_LINE_SIZE, | ||
| }; | ||
| use nom::character::complete::crlf; | ||
| use nom7 as nom; |
Member
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new parser should use nom 8
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Changes:
Link to ticket: https://redmine.openinfosecfoundation.org/issues/8276
Previous PR: #15648
SV_BRANCH=OISF/suricata-verify#2908