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Show every answer the portal remembers, and give SSH keys their missing half

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Claude-Session: https://claude.ai/code/session_01Ms2FbjQy31TVf3CEvQhGM8
This commit is contained in:
Gabriel Brown
2026-08-24 19:26:56 -04:00
parent 4ec8bd94d9
commit 6f0ce639d9
25 changed files with 3622 additions and 408 deletions
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config/dot/quickshell/scripts/panama-ssh-keys
+278 -7
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@@ -8,13 +8,21 @@ ssh-keygen to derive the PUBLIC key with an empty passphrase: it succeeds for an
unencrypted key and fails for an encrypted one, and either way the only thing it
can print is public material.
No passphrase passes through this tool at all. Adding an encrypted key to the
agent lets ssh-add prompt through the system's own askpass, which is where that
belongs -- a settings page collecting a passphrase and handing it on would be a
worse place for it to live, and putting one in argv would publish it to every
process on the machine.
A passphrase enters this tool in exactly one place -- creating a key -- and it
enters on standard input, which no other process can read. From there it is
typed at ssh-keygen over a pseudo-terminal, the same way a person would type it,
because the two obvious alternatives are both worse: a passphrase in argv is
published to every process on the machine, and a passphrase in a temporary file
is written to disk. It is never logged, never echoed back, and never included in
an error message.
Adding an existing encrypted key to the agent is different: no passphrase is
collected for that at all, because ssh-add prompts through the system's own
askpass, which is where that belongs.
panama-ssh-keys snapshot
panama-ssh-keys generate NAME COMMENT (passphrase on stdin)
panama-ssh-keys fix-permissions NAME
panama-ssh-keys agent-add PATH | agent-remove PATH
panama-ssh-keys forget-host HOST
"""
@@ -23,9 +31,14 @@ from __future__ import annotations
import json
import os
import pty
import re
import select
import shutil
import signal
import subprocess
import sys
import time
from pathlib import Path
SSH_DIR = Path.home() / ".ssh"
@@ -34,6 +47,23 @@ KNOWN_HOSTS = SSH_DIR / "known_hosts"
# A host as it may appear in known_hosts, including [host]:port forms.
HOST = re.compile(r"^[A-Za-z0-9._:\[\]-]{1,253}$")
# A key file name, and nothing that could be a path. No slash is in the class,
# so a name cannot describe another directory at all -- the resolve-and-compare
# below is the second lock on the same door rather than the only one.
KEY_NAME = re.compile(r"^[A-Za-z0-9_.-]{1,64}$")
# A key comment. Free text, but nothing that could break out of a terminal line
# or be mistaken for one of ssh-keygen's own prompts.
KEY_COMMENT = re.compile(r"^[^\x00-\x1f\x7f]{0,128}$")
# ssh-keygen's own floor. Checked here so the refusal arrives before a terminal
# is opened, rather than as a re-prompt nobody is there to answer.
MINIMUM_PASSPHRASE = 5
# Generating an ed25519 key takes milliseconds. The budget is this large only so
# that a machine starved of entropy fails with a message rather than a hang.
KEYGEN_TIMEOUT_SECONDS = 120.0
# gnome-keyring's agent, which is what runs on this desktop. Only used when the
# environment has not already named one, so an ssh-agent started by hand wins.
KEYRING_SOCKET = Path(os.environ.get("XDG_RUNTIME_DIR", "/run/user/1000")) / "keyring" / "ssh"
@@ -253,6 +283,217 @@ def agent_remove(path: str) -> None:
raise BoundaryError(detail[-1] if detail else "That key could not be removed.")
def resolve_new_key(name: str) -> Path:
"""Where a key by this name would go, or a refusal.
Refuses anything that already exists -- both halves, because a stray .pub
beside no private key still means ssh-keygen would be asked to overwrite,
and this tool does not overwrite keys. Losing a private key is not
recoverable and a settings page is the wrong place to learn that.
"""
if not KEY_NAME.match(name or "") or name in (".", ".."):
raise BoundaryError(
"A key name can use letters, numbers, dots, dashes and underscores.")
if name.endswith(".pub"):
raise BoundaryError("Name the key itself, not its public half.")
try:
SSH_DIR.mkdir(mode=0o700, parents=True, exist_ok=True)
directory = SSH_DIR.resolve(strict=True)
except OSError as error:
raise BoundaryError("The SSH directory could not be opened.") from error
if not directory.is_dir():
raise BoundaryError("The SSH directory is not a directory.")
target = directory / name
if target.parent.resolve(strict=True) != directory:
raise BoundaryError("That key is not in the SSH directory.")
public = Path(str(target) + ".pub")
for candidate in (target, public):
if candidate.exists() or candidate.is_symlink():
raise BoundaryError(f"{candidate.name} already exists, so nothing was written.")
return target
def terminal_environment() -> dict:
"""The environment ssh-keygen must run in to ask its question at the terminal.
This desktop sets SSH_ASKPASS_REQUIRE=prefer, which makes ssh-keygen open a
graphical passphrase dialog even when it has a perfectly good terminal in
front of it -- so the first version of this hung, waiting for a prompt that
had been drawn on somebody's screen instead. The terminal is supplied
deliberately here, so the askpass route is switched off just as deliberately.
LC_ALL is pinned so the prompts read below are the ones OpenSSH ships.
"""
environment = dict(os.environ)
environment["SSH_ASKPASS_REQUIRE"] = "never"
environment["LC_ALL"] = "C"
for name in ("SSH_ASKPASS", "DISPLAY", "WAYLAND_DISPLAY"):
environment.pop(name, None)
return environment
def type_at_keygen(command: list[str], passphrase: str) -> None:
"""Run ssh-keygen on a pseudo-terminal and answer its prompts.
ssh-keygen reads a passphrase through readpassphrase(), which opens
/dev/tty: a pipe on standard input is not read at all, which is why this
needs a terminal rather than a simpler subprocess call. The passphrase is
written to the terminal's master side, exactly as typing it would, and
ssh-keygen asks twice, so it is typed twice.
Nothing about the passphrase is kept. It is not written to disk, does not
appear in the command, and is scrubbed out of anything reported back in case
a future ssh-keygen ever echoes it.
"""
try:
pid, master = pty.fork()
except OSError as error:
raise BoundaryError("A terminal could not be opened for ssh-keygen.") from error
if pid == 0:
# The child. Nothing may return from here into the parent's code holding
# the parent's file descriptors, so a failed exec exits outright.
try:
os.execvpe(command[0], command, terminal_environment())
except OSError:
pass
os._exit(127)
typed = 0
pending = ""
transcript = ""
problem = ""
deadline = time.monotonic() + KEYGEN_TIMEOUT_SECONDS
while True:
remaining = deadline - time.monotonic()
if remaining <= 0:
problem = "ssh-keygen did not finish."
break
try:
ready, _, _ = select.select([master], [], [], min(remaining, 1.0))
except OSError:
break
if not ready:
continue
try:
chunk = os.read(master, 4096)
except OSError:
# EIO on Linux: the child closed the terminal, which is how a pty
# reports end of output.
break
if not chunk:
break
text = chunk.decode("utf-8", errors="replace")
pending += text
transcript += text
lowered = pending.lower()
# Matched on ssh-keygen's whole prompt rather than one word of it: the
# passphrase prompt quotes the key's path back, and "overwrite" is a
# perfectly legal key name.
if "overwrite (y/n)" in lowered:
# Unreachable in practice -- an existing key is refused before this
# runs -- but answering anything other than "no" here would destroy
# a key, so it answers no and stops.
os.write(master, b"n\n")
problem = "That key already exists, so nothing was written."
break
if "passphrase is too short" in lowered:
problem = (f"ssh-keygen wants a passphrase of at least "
f"{MINIMUM_PASSPHRASE} characters.")
break
if "passphrases do not match" in lowered:
problem = "Those passphrases did not match."
break
if typed < 2 and "passphrase" in lowered and pending.rstrip().endswith(":"):
os.write(master, passphrase.encode("utf-8") + b"\n")
typed += 1
pending = ""
if problem:
try:
os.kill(pid, signal.SIGKILL)
except OSError:
pass
try:
os.close(master)
except OSError:
pass
try:
_, status = os.waitpid(pid, 0)
except OSError:
status = 0
if problem:
raise BoundaryError(problem)
if not (os.WIFEXITED(status) and os.WEXITSTATUS(status) == 0):
detail = scrubbed(transcript, passphrase)
last = [line.strip() for line in detail.splitlines() if line.strip()]
raise BoundaryError(last[-1] if last else "ssh-keygen could not create that key.")
def scrubbed(text: str, secret: str) -> str:
return text.replace(secret, "********") if secret else text
def generate(name: str, comment: str, passphrase: str, allow_empty: bool) -> None:
"""Create an ed25519 key.
ed25519 and nothing else: it is the key everything current accepts, the
choice between it and RSA is not one a settings page should make someone
make, and offering a size field for a curve that has one size would be
theatre.
"""
if not KEY_COMMENT.match(comment or ""):
raise BoundaryError("A comment cannot contain control characters.")
if "\n" in passphrase or "\r" in passphrase:
raise BoundaryError("A passphrase cannot contain a line break.")
if passphrase == "":
if not allow_empty:
raise BoundaryError(
"A passphrase is required. A key with none is usable by anyone "
"who reads the file.")
elif len(passphrase) < MINIMUM_PASSPHRASE:
raise BoundaryError(
f"ssh-keygen wants a passphrase of at least {MINIMUM_PASSPHRASE} characters.")
if shutil.which("ssh-keygen") is None:
raise BoundaryError("ssh-keygen is not installed.")
target = resolve_new_key(name)
command = ["ssh-keygen", "-t", "ed25519", "-f", str(target)]
if comment:
command += ["-C", comment]
type_at_keygen(command, passphrase)
if not target.is_file() or not Path(str(target) + ".pub").is_file():
raise BoundaryError("ssh-keygen finished but the key is not there.")
def fix_permissions(name: str) -> None:
"""Make a private key readable only by its owner.
ssh refuses to use a key other people can read, and says so in a message
most people meet for the first time at the worst moment. The path is
resolved and compared against the SSH directory first, so a name that is a
link to something elsewhere is refused rather than followed -- this changes
a file's mode, and that is not a thing to do to a file you have not checked.
"""
if not KEY_NAME.match(name or "") or name in (".", ".."):
raise BoundaryError("That is not a key name.")
key = resolve_key(str(SSH_DIR / name))
try:
os.chmod(key, 0o600)
except OSError as error:
raise BoundaryError("That key's permissions could not be changed.") from error
def forget_host(host: str) -> None:
"""Drop a host's keys from known_hosts.
@@ -271,13 +512,42 @@ def forget_host(host: str) -> None:
raise BoundaryError(detail[-1] if detail else "That host could not be removed.")
def read_passphrase() -> str:
"""The passphrase, from standard input, and only from there.
One trailing newline is dropped because the caller writes one to end the
line; anything else is taken literally, including spaces, because a
passphrase is allowed to end in one.
"""
try:
raw = sys.stdin.buffer.read().decode("utf-8")
except (OSError, UnicodeDecodeError) as error:
raise BoundaryError("The passphrase could not be read.") from error
if raw.endswith("\n"):
raw = raw[:-1]
if raw.endswith("\r"):
raw = raw[:-1]
return raw
def main(arguments: list[str]) -> int:
try:
if arguments == ["snapshot"]:
print(json.dumps(snapshot(), separators=(",", ":")))
return 0
if len(arguments) == 2 and arguments[0] == "agent-add":
if arguments and arguments[0] == "generate":
# The flag exists so a machine-shaped caller can ask for a key with
# no passphrase deliberately. Panama's own page never passes it: it
# requires a passphrase and validates that both fields match.
allow_empty = "--no-passphrase" in arguments[1:]
rest = [value for value in arguments[1:] if value != "--no-passphrase"]
if len(rest) != 2:
raise BoundaryError("Usage: panama-ssh-keys generate NAME COMMENT")
generate(rest[0], rest[1], read_passphrase(), allow_empty)
elif len(arguments) == 2 and arguments[0] == "fix-permissions":
fix_permissions(arguments[1])
elif len(arguments) == 2 and arguments[0] == "agent-add":
agent_add(arguments[1])
elif len(arguments) == 2 and arguments[0] == "agent-remove":
agent_remove(arguments[1])
@@ -285,7 +555,8 @@ def main(arguments: list[str]) -> int:
forget_host(arguments[1])
else:
raise BoundaryError(
"Usage: panama-ssh-keys snapshot | agent-add PATH | agent-remove PATH | "
"Usage: panama-ssh-keys snapshot | generate NAME COMMENT | "
"fix-permissions NAME | agent-add PATH | agent-remove PATH | "
"forget-host HOST")
except BoundaryError as error:
try: