Miscellaneous builder hardening #16
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marmarek
requested changes
Apr 3, 2022
This avoids having to do so in the qrexec service.
Avoids any potential nasties.
Lots of exploits involve passing huge amounts of data, so impose an arbitrary limit of 4096 bytes.
Makes errors more likely to be caught.
Service arguments are validated by qrexec, so they can only contain a small subset of characters. As it happens, the only character the shell script winds up rejecting is '.'. The rest would have been mangled by qrexec already.
They make no sense here, and they can confuse shell scripts.
There is no reason for them to be longer than this. Admittedly, this number is arbitrary.
All qrexec-builder commands are 1 line.
Nothing more should follow this.
instead of using head(1) and a temporary file.
Bad characters in commands could potentially confuse shell scripts, so reject them.
Should be a no-op because the grep command already only produces decent characters.
Needed for -o pipefail
They are stripped out by the webhook now.
This allows the qrexec service to be stricter, parsing-wise.
Pointless attack surface
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qubes-builder-githubis exposed to untrusted input from the network, so harden it a bit more.Not tested because I am not really sure how to test this.