Own user accounts and sharing

Two of the panels this desktop still handed to GNOME Settings. Users manages the account through accountsservice -- the same daemon GNOME's panel drives, so a name or picture set here is what the login screen and lock screen read. Name, picture, account type, password, automatic login, and adding or removing other accounts. Every change is authorized by polkit through the agent this session already runs; a dismissed prompt is a normal outcome and says so. A new password is read from the helper's stdin, hashed by openssl reading its own stdin, and handed over D-Bus from inside that process. It is never an argument: argv is world-readable through /proc, so a password passed that way is published to every process on the machine. Removing an account takes two presses and says it destroys their files; the last administrator cannot be removed or demoted, because a machine nobody can administer is not a state to offer. Sharing reports what is actually true, including "the software for this is not installed" -- the honest answer for Samba here, and the case the panel it replaces shows as a switch that does nothing. Password sign-in is reported from sshd's configuration rather than assumed: claiming "keys only" when the file is silent would state a security property that cannot be backed up. The Control Center now draws the account's real picture and name. A generic glyph sat there while a real avatar was already set, which made the desktop look like it did not know whose it was. Also here: the KDE Connect contract no longer requires a phone to be awake. kdeconnectd drops its device objects for a phone it has not seen recently while the pairing survives in its config, so demanding one failed whenever the phone was off. Claude-Session: https://claude.ai/code/session_01BRvzt4H8XXLPVH5MyYdk9L
2026-08-19 13:05:13 -04:00
parent e0c0e53ae0
commit a23b42841a
22 changed files with 1817 additions and 10 deletions
@@ -0,0 +1,272 @@
+#!/usr/bin/env python3
+
+"""User accounts, through accountsservice -- the same daemon GNOME's Users panel
+drives.
+
+Everything here that changes something is authorized by polkit, which prompts
+through the agent this desktop already runs. This script never asks for a
+password itself and never holds an administrator credential.
+
+The one credential it does handle is a NEW password being set. That is read
+from stdin, hashed by openssl reading its own stdin, and handed to
+accountsservice over D-Bus from inside this process. It is never an argument:
+argv is world-readable through /proc, so a password -- or even its hash --
+passed that way is published to every process on the machine.
+
+    panama-accounts snapshot
+    panama-accounts set-real-name USER NAME
+    panama-accounts set-icon USER PATH
+    panama-accounts set-account-type USER standard|administrator
+    panama-accounts set-automatic-login USER true|false
+    panama-accounts set-password USER          (new password on stdin)
+    panama-accounts create-user USERNAME REALNAME standard|administrator
+    panama-accounts delete-user USERNAME [keep-files|remove-files]
+"""
+
+from __future__ import annotations
+
+import json
+import os
+import re
+import subprocess
+import sys
+
+ACCOUNTS = "org.freedesktop.Accounts"
+ACCOUNTS_PATH = "/org/freedesktop/Accounts"
+USER_INTERFACE = "org.freedesktop.Accounts.User"
+
+# Account types as accountsservice numbers them.
+STANDARD, ADMINISTRATOR = 0, 1
+
+USERNAME = re.compile(r"^[a-z_][a-z0-9_-]{0,31}$")
+
+
+class BoundaryError(RuntimeError):
+    """A user-visible validation or permission failure."""
+
+
+def bus():
+    try:
+        import gi
+
+        gi.require_version("Gio", "2.0")
+        from gi.repository import Gio, GLib
+
+        return Gio, GLib, Gio.bus_get_sync(Gio.BusType.SYSTEM, None)
+    except Exception as error:  # noqa: BLE001 - no bus is a legitimate state
+        raise BoundaryError("The account service is not answering.") from error
+
+
+def call(path: str, interface: str, method: str, parameters=None, reply=None):
+    Gio, GLib, connection = bus()
+    try:
+        result = connection.call_sync(
+            ACCOUNTS, path, interface, method, parameters,
+            GLib.VariantType(reply) if reply else None,
+            Gio.DBusCallFlags.NONE, 120000, None)
+    except Exception as error:  # noqa: BLE001
+        message = str(error)
+        # Polkit's own refusal is the common case and deserves plain words
+        # rather than a D-Bus error string.
+        if "not authorized" in message.lower() or "dismissed" in message.lower():
+            raise BoundaryError("That change was not authorized.") from error
+        raise BoundaryError(_clean(message)) from error
+    return result.unpack() if result is not None else None
+
+
+def _clean(message: str) -> str:
+    """The last useful sentence of a D-Bus error, without the type prefix."""
+    trimmed = re.sub(r"^GDBus\.Error:[^:]+:\s*", "", message).strip()
+    return trimmed.splitlines()[0][:200] if trimmed else "That change failed."
+
+
+def properties(path: str) -> dict:
+    Gio, GLib, connection = bus()
+    result = connection.call_sync(
+        ACCOUNTS, path, "org.freedesktop.DBus.Properties", "GetAll",
+        GLib.Variant("(s)", (USER_INTERFACE,)), GLib.VariantType("(a{sv})"),
+        Gio.DBusCallFlags.NONE, 20000, None)
+    return result.unpack()[0]
+
+
+def user_path(username: str) -> str:
+    if not USERNAME.fullmatch(username or ""):
+        raise BoundaryError("That is not a user name.")
+    from gi.repository import GLib
+
+    return call(ACCOUNTS_PATH, ACCOUNTS, "FindUserByName",
+                GLib.Variant("(s)", (username,)), "(o)")[0]
+
+
+def describe(path: str) -> dict:
+    values = properties(path)
+    icon = str(values.get("IconFile") or "")
+    return {
+        "path": path,
+        "userName": str(values.get("UserName") or ""),
+        "realName": str(values.get("RealName") or ""),
+        # Reported only when it is actually there: accountsservice keeps the
+        # path in its database whether or not a file exists, so a deleted
+        # avatar otherwise shows as a broken image.
+        "iconFile": icon if icon and os.path.isfile(icon) else "",
+        "administrator": int(values.get("AccountType") or 0) == ADMINISTRATOR,
+        "locked": bool(values.get("Locked")),
+        "automaticLogin": bool(values.get("AutomaticLogin")),
+        "loginTime": int(values.get("LoginTime") or 0),
+        "shell": str(values.get("Shell") or ""),
+        "homeDirectory": str(values.get("HomeDirectory") or ""),
+        "systemAccount": bool(values.get("SystemAccount")),
+        "uid": int(values.get("Uid") or 0),
+    }
+
+
+def snapshot() -> dict:
+    paths = call(ACCOUNTS_PATH, ACCOUNTS, "ListCachedUsers", None, "(ao)")[0]
+    users = [describe(path) for path in paths]
+    users = [user for user in users if not user["systemAccount"]]
+    users.sort(key=lambda user: user["uid"])
+    me = os.environ.get("USER") or ""
+    return {
+        "users": users,
+        "currentUser": me,
+        # Removing the only administrator would leave a machine nobody can
+        # administer, so the page needs to know rather than find out.
+        "administratorCount": sum(1 for user in users if user["administrator"]),
+        "error": "",
+    }
+
+
+def set_real_name(username: str, name: str) -> None:
+    from gi.repository import GLib
+
+    if len(name) > 128 or "\n" in name or ":" in name:
+        raise BoundaryError("That name cannot be used.")
+    call(user_path(username), USER_INTERFACE, "SetRealName",
+         GLib.Variant("(s)", (name,)))
+
+
+def set_icon(username: str, path: str) -> None:
+    from gi.repository import GLib
+
+    if not os.path.isfile(path):
+        raise BoundaryError("That picture no longer exists.")
+    call(user_path(username), USER_INTERFACE, "SetIconFile",
+         GLib.Variant("(s)", (path,)))
+
+
+def set_account_type(username: str, kind: str) -> None:
+    from gi.repository import GLib
+
+    if kind not in ("standard", "administrator"):
+        raise BoundaryError("That is not an account type.")
+    call(user_path(username), USER_INTERFACE, "SetAccountType",
+         GLib.Variant("(i)", (ADMINISTRATOR if kind == "administrator" else STANDARD,)))
+
+
+def set_automatic_login(username: str, enabled: bool) -> None:
+    from gi.repository import GLib
+
+    call(user_path(username), USER_INTERFACE, "SetAutomaticLogin",
+         GLib.Variant("(b)", (enabled,)))
+
+
+def set_password(username: str) -> None:
+    """Set a new password, read from stdin and never named on a command line."""
+    secret = sys.stdin.buffer.read()
+    # A trailing newline from a pipe is not part of the password.
+    if secret.endswith(b"\n"):
+        secret = secret[:-1]
+    if not secret:
+        raise BoundaryError("No password was provided.")
+    if len(secret) < 6:
+        raise BoundaryError("That password is too short.")
+
+    # openssl reads the password on ITS stdin too, so the cleartext never
+    # appears in a process listing at any point in the chain.
+    hashed = subprocess.run(["openssl", "passwd", "-6", "-stdin"],
+                            input=secret, capture_output=True, timeout=30, check=False)
+    if hashed.returncode != 0 or not hashed.stdout.strip():
+        raise BoundaryError("The password could not be prepared.")
+
+    from gi.repository import GLib
+
+    call(user_path(username), USER_INTERFACE, "SetPassword",
+         GLib.Variant("(ss)", (hashed.stdout.decode().strip(), "")))
+
+
+def create_user(username: str, real_name: str, kind: str) -> None:
+    from gi.repository import GLib
+
+    if not USERNAME.fullmatch(username or ""):
+        raise BoundaryError("A user name may use lowercase letters, digits, - and _.")
+    if kind not in ("standard", "administrator"):
+        raise BoundaryError("That is not an account type.")
+    call(ACCOUNTS_PATH, ACCOUNTS, "CreateUser",
+         GLib.Variant("(ssi)", (username, real_name,
+                                ADMINISTRATOR if kind == "administrator" else STANDARD)),
+         "(o)")
+
+
+def delete_user(username: str, files: str) -> None:
+    from gi.repository import GLib
+
+    if files not in ("keep-files", "remove-files"):
+        raise BoundaryError("Say whether to keep or remove the home directory.")
+    if username == (os.environ.get("USER") or ""):
+        raise BoundaryError("You cannot delete the account you are signed in to.")
+
+    state = snapshot()
+    target = next((user for user in state["users"] if user["userName"] == username), None)
+    if target is None:
+        raise BoundaryError("That account no longer exists.")
+    if target["administrator"] and state["administratorCount"] <= 1:
+        raise BoundaryError("That is the only administrator; the machine would have none.")
+
+    call(ACCOUNTS_PATH, ACCOUNTS, "DeleteUser",
+         GLib.Variant("(xb)", (target["uid"], files == "remove-files")))
+
+
+def main(arguments: list[str]) -> int:
+    try:
+        if arguments == ["snapshot"]:
+            print(json.dumps(snapshot(), separators=(",", ":")))
+            return 0
+
+        if len(arguments) == 3 and arguments[0] == "set-real-name":
+            set_real_name(arguments[1], arguments[2])
+        elif len(arguments) == 3 and arguments[0] == "set-icon":
+            set_icon(arguments[1], arguments[2])
+        elif len(arguments) == 3 and arguments[0] == "set-account-type":
+            set_account_type(arguments[1], arguments[2])
+        elif len(arguments) == 3 and arguments[0] == "set-automatic-login":
+            set_automatic_login(arguments[1], arguments[2] == "true")
+        elif len(arguments) == 2 and arguments[0] == "set-password":
+            set_password(arguments[1])
+        elif len(arguments) == 4 and arguments[0] == "create-user":
+            create_user(arguments[1], arguments[2], arguments[3])
+        elif len(arguments) == 3 and arguments[0] == "delete-user":
+            delete_user(arguments[1], arguments[2])
+        else:
+            raise BoundaryError(
+                "Usage: panama-accounts snapshot | set-real-name USER NAME | "
+                "set-icon USER PATH | set-account-type USER standard|administrator | "
+                "set-automatic-login USER true|false | set-password USER | "
+                "create-user USERNAME REALNAME standard|administrator | "
+                "delete-user USERNAME keep-files|remove-files")
+    except BoundaryError as error:
+        # Answers with the fresh state plus the message, so a page never has to
+        # ask twice to find out what happened.
+        try:
+            state = snapshot()
+        except BoundaryError:
+            state = {"users": [], "currentUser": "", "administratorCount": 0}
+        state["error"] = str(error)
+        print(json.dumps(state, separators=(",", ":")))
+        return 0
+
+    print(json.dumps(snapshot(), separators=(",", ":")))
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main(sys.argv[1:]))