🔀 Merge v0.6.4.1 patches#702
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Also update internal RawText docs.
It's bad behavior to send a non-synchronizing literal that's too large. This forces the server to choose between reading but ignoring the bytes or closing the connection. But, for servers that _don't_ support non-synchronizing literals, this could be another CRLF/command injection attack vector. If a server sees the `}\r\n` but can't parse the literal bytesize, it may decide to close the connection, and all is fine. But, a server _might_ respond to any unparseable command line (ending in `CRLF`) with `BAD`, then interpret the literal as the next command. In that case, a CRLF/command injection could succeed. Fortunately, `LITERAL-` is supported by most IMAP servers. So this is not expected to be widely exploitable.
This shares most of the validation implementation with RawText, via an extracted shared superclass. Please note: in currently released `net-imap`, QuotedString is _not_ used to quote regular string arguments. It's currently only used by `Net::IMAP#id` (the `ID` extension). Without this patch, `Net::IMAP#id` is vulnerable to the same CRLF injection issues in GHSA-75xq-5h9v-w6px and GHSA-hm49-wcqc-g2xg. The string will be quoted, which may limit the ability to inject some commands. Presumably, `Net::IMAP#id` is unlikely to be called with user-provided input, making this less likely to be exploitable. Nevertheless, CRLF injection should be prevented!
This still allows the argument to be a single string with multiple space-delimited arguments. It splits the string first, and validates the substrings.
Zero-length literals are explicitly allowed by the RFCs and this did not
catch text that ends with `{0}` or `{0+}`. This leaves RawData able to
absorb the `CRLF` that ends the command, and thus absorb the following
command into itself.
Ultimately, we don't care if the `number64` is encoded correctly nor
whether it claims to be a binary literal. So I've simplified the regexp
by dropping `~?` and using `\d+` for the number.
This removes the duplicated string quoting implementation. It also introduces stricter enforcement of `quoted` string validation..
🥅 Validate `ID` values contain only valid bytes
🥅 Validate `#enable` arguments are all atoms
…teral-marker-validation
🐛 Prevent trailing `{0}` in RawData validation
These tests can raise `Errno::ECONNREST, "Connection reset"` in the server thread. I've only seen it in TruffleRuby (semi-reliably) and MacOS (flaky), but probably it's a timing issue and can happen elsewhere too?
…l-support 🥅 Validate non-synchronizing literals support
nevans
added
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The
v0.6.4-patchesbranch (forv0.6.4.1) branched off from an earlier commit. This merges the following PRs back intomaster:IDvalues contain only valid bytes #698#enablearguments are all atoms #699{0}in RawData validation #700