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Summary: Fixes T2229. This sets the stage for a patch similar to D7417, but for SSH. In particular, SSH 6.2 introduced an `AuthorizedKeysCommand` directive, which lets us do this in a mostly-reasonable way without needing users to patch sshd (if they have a recent enough version, at least). The way the `AuthorizedKeysCommand` works is that it gets run and produces an `authorized_keys`-style file fragment. This isn't ideal, because we have to dump every key into the result, but should be fine for most installs. The earlier patch against `sshd` passes the public key itself, which allows the script to just look up the key. We might use this eventually, since it can scale much better, so I haven't removed it. Generally, auth is split into two scripts now which mostly do the same thing: - `ssh-auth` is the AuthorizedKeysCommand auth, which takes nothing and dumps the whole keyfile. - `ssh-auth-key` is the slightly cleaner and more scalable (but patch-dependent) version, which takes the public key and dumps only matching options. I also reworked the argument parsing to be a bit more sane. Test Plan: This is somewhat-intentionally a bit obtuse since I don't really want anyone using it yet, but basically: - Copy `phabricator-ssh-hook.sh` to somewhere like `/usr/libexec/openssh/`, chown it `root` and chmod it `500`. - This script should probably also do a username check in the future. - Create a copy of `sshd_config` and fix the paths/etc. Point the KeyScript at your copy of the hook. - Start a copy of sshd (6.2 or newer) with `-f <your config file>` and maybe `-d -d -d` to foreground and debug. - Run `ssh -p 2222 localhost` or similar. Specifically, I did this setup and then ran a bunch of commands like: - `ssh host` (denied, no command) - `ssh host ls` (denied, not supported) - `echo '{}' | ssh host conduit conduit.ping` (works) Reviewers: btrahan Reviewed By: btrahan CC: hach-que, aran Maniphest Tasks: T2229, T2230 Differential Revision: https://secure.phabricator.com/D7419
24 lines
588 B
Text
24 lines
588 B
Text
###
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### WARNING: This feature is new and experimental. Use it at your own risk!
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###
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# You must have OpenSSHD 6.2 or newer; support for AuthorizedKeysCommand was
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# added in this version.
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Port 2222
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AuthorizedKeysCommand /etc/phabricator-ssh-hook.sh
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AuthorizedKeysCommandUser some-unprivileged-user
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# You may need to tweak these options, but mostly they just turn off everything
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# dangerous.
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Protocol 2
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PermitRootLogin no
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AllowAgentForwarding no
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AllowTcpForwarding no
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PrintMotd no
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PrintLastLog no
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PasswordAuthentication no
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AuthorizedKeysFile none
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PidFile /var/run/sshd-phabricator.pid
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