Passage (short for "Pass Agent") is a Go process that serves as caching proxy for macOS keychain items.
It is intended to fulfil the use case where you have a command-line process that needs to periodically access a passphrase in the keychain, but you don't want to have to click "Allow" every single time (too cumbersome), nor "Always Allow" (too coarse). For more information, see Security, below.
If you have a working Go environment and $GOPATH is set, you can do:
go get github.com/wincent/passage
Additionally, you will need to install the keybase/go-keychain library as a dependency:
go get github.com/keybase/go-keychain
To build manually:
cd $GOPATH/src/wincent/passage
go build
sudo cp passage /usr/local/bin
cp contrib/com.wincent.passage.plist ~/Library/LaunchAgents
# NOTE: This won't work if run inside a tmux session:
launchctl load -w -S Aqua ~/Library/LaunchAgents/com.wincent.passage.plist
Send a JSON object with keys "service" and "account" to the Passage socket at ~/.passage.sock. On the first request, you may see a keychain permission dialog, but on subsequent requests, you'll get a cached result back immediately.
echo '{"service":"test item","account":"test name"}' | nc -U ~/.passage.sock
The resulting password is written back over the socket. You could call this a "write of Passage" (ha!). In the event that the item is missing or there is an error, the connection closes without any output, although errors do get printed to the standard output of the Passage process itself. This is for convenient consumption by clients (ie. so that they don't have to implement JSON parsing themselves).
There are two ways to invalidate the cache. One is to just restart the Passage process. The other is to send it a SIGUSR1 signal.
You'll need the process PID in order to do that, and you can get it in several ways:
# The old-fashioned way:
ps xww | grep passage
# Or to be more specific, assuming you installed and ran from `/usr/local/bin/`:
ps xww | grep /usr/local/bin/passage | grep -v grep
# The first column so you can extract it like this:
ps xww | grep /usr/local/bin/passage | grep -v grep | awk '{print $1}'
# If you launched using launchctl (but note: only works outside tmux):
launchctl list | grep passage
# The PID is the first column in the output of `launchctl list`, so you can
# extract it like this:
launchctl list | grep passage | awk '{print $1}'
# Once you've got the PID, say in a variable $PID, send the signal like this:
kill -USR1 $PID
# A more clever way using launchctl that works anywhere (including inside tmux)
# and doesn't just get the PID but actually sends the signal as well:
launchctl kill SIGUSR1 "gui/$(id -u)/com.wincent.passage"
There are no options. This was quickly hacked together to address a specific need.
The ~/.passage.sock socket is created with user-only (0700) permissions, but can still be accessed by privileged users and processes running on the system. As such, it falls somewhere in the middle of the spectrum of password storage (ordered approximately from most to least secure):
- Storage in the system keychain, requiring explicit "Allow" intervention for each access: This is the most secure, but also the most onerous. Key material only leaves the key chain with active approval (interaction with an intrusive GUI dialog).
- Temporary storage in a process like
ssh-agent: This is quite secure not only because of the limited storage duration, but because the key material never leaves the agent; rather, other processes delegate work to be done by the agent. For example, whensshtries to connect to a server, it will askssh-agentto perform the operations for private-key authentication, but there is no straightforward way to extract the actual private key material for the agent. The most a local attacker can do is perform operations as you, and only while they have access to the agent. Note, however, this approach is not viable for situations like those in which you do need access to the private key. - Temporary storage in the memory of the
passageprocess: Passphrases can only be inserted intopassagevia explicit approval, and only remain there for the duration of the session. You can shorten the duration in various ways, such as:- Terminating the app or logging out.
- Setting up a cron job to periodically send a
SIGUSR1topassageto cause it to drop its cache; you can do this withcrontab -eand a method like thelaunchctl killone documented above. - Arranging to send
SIGUSR1whenever the screensaver kicks in or the screen locks (something you should be able to do with a tool like Hammerspoon).
- Storage in the system keychain, having previously granted "Always Allow" access: This is problematic if you're using the
securitycommand-line tool provided by Apple, because once you've granted "Always Allow", you will never be asked for permission again. Even if you intended to grant access only tomy-special-script.sh, the permission will actually be associated with thesecuritytool, which any process can call. So here the security is contingent on an attacker not being able to run code as you (or trick/coerce you into running it). - Storage in plain-text on the filesystem: The security here is only so good as the security of the filesystem: privileged users will be able to retrieve the password regardless of filesystem permission. An unprivileged, determined attacker with local access will be able to elevate privileges by one means or another and gain access, even in the face of restrictive permissions.
Passage uses the keybase/go-keychain library to access the keychain, which currently only knows how to read "generic" (A.K.A. "application") passwords, not "Internet" passwords.
Passage is written and maintained by Greg Hurrell (greg@hurrell.net).
Mirrors exist at:
- https://github.com/wincent/passage
- https://gitlab.com/wincent/passage
- https://bitbucket.org/ghurrell/passage
Patches are welcome via the usual mechanisms (pull requests, email, posting to the project issue tracker etc).
The official website for Passage is:
Bug reports should be submitted to the issue tracker at:
Please see CHANGELOG.md in this repository.
Copyright 2016-present Greg Hurrell. All rights reserved.
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