Add Password Hardening CLI support (sonic-net#2338)

- What I did
Add Password Hardening CLI

- How I did it
created the CLI by using YANG model generator, the YANG model can be found in the password hardening HLD https://github.com/Azure/SONiC/blob/master/doc/passw_hardening/hld_password_hardening.md#TestPlan
and also in sonic-buildimage will be merged in the path: src/sonic-yang-models/yang-models/sonic-passwh.yang

- How to verify it
Manually:
you can use configurations command like"config passw-hardening policies " or
"show passw-hardening policies" (more examples in the HLD.)

Auto:
1.There are unitest of each policy including good & bad flow in this commit, that should pass.
2.There are tests in sonic-mgmt repo in the path: sonic-mgmt/tests/passw_hardening/
the test are end to end test and the are testing the config/show CLI commands as well.

config/plugins/sonic-passwh_yang.py

@@ -0,0 +1,380 @@
+import copy
+import click
+import utilities_common.cli as clicommon
+import utilities_common.general as general
+from config import config_mgmt
+
+
+# Load sonic-cfggen from source since /usr/local/bin/sonic-cfggen does not have .py extension.
+sonic_cfggen = general.load_module_from_source('sonic_cfggen', '/usr/local/bin/sonic-cfggen')
+
+
+def exit_with_error(*args, **kwargs):
+    """ Print a message with click.secho and abort CLI.
+
+    Args:
+        args: Positional arguments to pass to click.secho
+        kwargs: Keyword arguments to pass to click.secho
+    """
+
+    click.secho(*args, **kwargs)
+    raise click.Abort()
+
+
+def validate_config_or_raise(cfg):
+    """ Validate config db data using ConfigMgmt.
+
+    Args:
+        cfg (Dict): Config DB data to validate.
+    Raises:
+        Exception: when cfg does not satisfy YANG schema.
+    """
+
+    try:
+        cfg = sonic_cfggen.FormatConverter.to_serialized(copy.deepcopy(cfg))
+        config_mgmt.ConfigMgmt().loadData(cfg)
+    except Exception as err:
+        raise Exception('Failed to validate configuration: {}'.format(err))
+
+
+def update_entry_validated(db, table, key, data, create_if_not_exists=False):
+    """ Update entry in table and validate configuration.
+    If attribute value in data is None, the attribute is deleted.
+
+    Args:
+        db (swsscommon.ConfigDBConnector): Config DB connector obect.
+        table (str): Table name to add new entry to.
+        key (Union[str, Tuple]): Key name in the table.
+        data (Dict): Entry data.
+        create_if_not_exists (bool):
+            In case entry does not exists already a new entry
+            is not created if this flag is set to False and
+            creates a new entry if flag is set to True.
+    Raises:
+        Exception: when cfg does not satisfy YANG schema.
+    """
+
+    cfg = db.get_config()
+    cfg.setdefault(table, {})
+
+    if not data:
+        raise Exception(f"No field/values to update {key}")
+
+    if create_if_not_exists:
+        cfg[table].setdefault(key, {})
+
+    if key not in cfg[table]:
+        raise Exception(f"{key} does not exist")
+
+    entry_changed = False
+    for attr, value in data.items():
+        if value == cfg[table][key].get(attr):
+            continue
+        entry_changed = True
+        if value is None:
+            cfg[table][key].pop(attr, None)
+        else:
+            cfg[table][key][attr] = value
+
+    if not entry_changed:
+        return
+
+    validate_config_or_raise(cfg)
+    db.set_entry(table, key, cfg[table][key])
+
+
+@click.group(name="passw-hardening",
+             cls=clicommon.AliasedGroup)
+def PASSW_HARDENING():
+    """ PASSWORD HARDENING part of config_db.json """
+
+    pass
+
+
+
+
+@PASSW_HARDENING.group(name="policies",
+                        cls=clicommon.AliasedGroup)
+@clicommon.pass_db
+def PASSW_HARDENING_POLICIES(db):
+    """  """
+
+    pass
+
+
+
+
+@PASSW_HARDENING_POLICIES.command(name="state")
+
+@click.argument(
+    "state",
+    nargs=1,
+    required=True,
+)
+@clicommon.pass_db
+def PASSW_HARDENING_POLICIES_state(db, state):
+    """ state of the feature """
+
+    table = "PASSW_HARDENING"
+    key = "POLICIES"
+    data = {
+        "state": state,
+    }
+    try:
+        update_entry_validated(db.cfgdb, table, key, data, create_if_not_exists=True)
+    except Exception as err:
+        exit_with_error(f"Error: {err}", fg="red")
+
+
+
+@PASSW_HARDENING_POLICIES.command(name="expiration")
+
+@click.argument(
+    "expiration",
+    nargs=1,
+    required=True,
+)
+@clicommon.pass_db
+def PASSW_HARDENING_POLICIES_expiration(db, expiration):
+    """ expiration time (days unit) """
+
+    table = "PASSW_HARDENING"
+    key = "POLICIES"
+    data = {
+        "expiration": expiration,
+    }
+    try:
+        update_entry_validated(db.cfgdb, table, key, data, create_if_not_exists=True)
+    except Exception as err:
+        exit_with_error(f"Error: {err}", fg="red")
+
+
+
+@PASSW_HARDENING_POLICIES.command(name="expiration-warning")
+
+@click.argument(
+    "expiration-warning",
+    nargs=1,
+    required=True,
+)
+@clicommon.pass_db
+def PASSW_HARDENING_POLICIES_expiration_warning(db, expiration_warning):
+    """ expiration warning time (days unit) """
+
+    table = "PASSW_HARDENING"
+    key = "POLICIES"
+    data = {
+        "expiration_warning": expiration_warning,
+    }
+    try:
+        update_entry_validated(db.cfgdb, table, key, data, create_if_not_exists=True)
+    except Exception as err:
+        exit_with_error(f"Error: {err}", fg="red")
+
+
+
+@PASSW_HARDENING_POLICIES.command(name="history-cnt")
+
+@click.argument(
+    "history-cnt",
+    nargs=1,
+    required=True,
+)
+@clicommon.pass_db
+def PASSW_HARDENING_POLICIES_history_cnt(db, history_cnt):
+    """ num of old password that the system will recorded """
+
+    table = "PASSW_HARDENING"
+    key = "POLICIES"
+    data = {
+        "history_cnt": history_cnt,
+    }
+    try:
+        update_entry_validated(db.cfgdb, table, key, data, create_if_not_exists=True)
+    except Exception as err:
+        exit_with_error(f"Error: {err}", fg="red")
+
+
+
+@PASSW_HARDENING_POLICIES.command(name="len-min")
+
+@click.argument(
+    "len-min",
+    nargs=1,
+    required=True,
+)
+@clicommon.pass_db
+def PASSW_HARDENING_POLICIES_len_min(db, len_min):
+    """ password min length """
+
+    table = "PASSW_HARDENING"
+    key = "POLICIES"
+    data = {
+        "len_min": len_min,
+    }
+    try:
+        update_entry_validated(db.cfgdb, table, key, data, create_if_not_exists=True)
+    except Exception as err:
+        exit_with_error(f"Error: {err}", fg="red")
+
+
+
+@PASSW_HARDENING_POLICIES.command(name="reject-user-passw-match")
+
+@click.argument(
+    "reject-user-passw-match",
+    nargs=1,
+    required=True,
+)
+@clicommon.pass_db
+def PASSW_HARDENING_POLICIES_reject_user_passw_match(db, reject_user_passw_match):
+    """ username password match """
+
+    table = "PASSW_HARDENING"
+    key = "POLICIES"
+    data = {
+        "reject_user_passw_match": reject_user_passw_match,
+    }
+    try:
+        update_entry_validated(db.cfgdb, table, key, data, create_if_not_exists=True)
+    except Exception as err:
+        exit_with_error(f"Error: {err}", fg="red")
+
+
+
+@PASSW_HARDENING_POLICIES.command(name="lower-class")
+
+@click.argument(
+    "lower-class",
+    nargs=1,
+    required=True,
+)
+@clicommon.pass_db
+def PASSW_HARDENING_POLICIES_lower_class(db, lower_class):
+    """ password lower chars policy """
+
+    table = "PASSW_HARDENING"
+    key = "POLICIES"
+    data = {
+        "lower_class": lower_class,
+    }
+    try:
+        update_entry_validated(db.cfgdb, table, key, data, create_if_not_exists=True)
+    except Exception as err:
+        exit_with_error(f"Error: {err}", fg="red")
+
+
+
+@PASSW_HARDENING_POLICIES.command(name="upper-class")
+
+@click.argument(
+    "upper-class",
+    nargs=1,
+    required=True,
+)
+@clicommon.pass_db
+def PASSW_HARDENING_POLICIES_upper_class(db, upper_class):
+    """ password upper chars policy """
+
+    table = "PASSW_HARDENING"
+    key = "POLICIES"
+    data = {
+        "upper_class": upper_class,
+    }
+    try:
+        update_entry_validated(db.cfgdb, table, key, data, create_if_not_exists=True)
+    except Exception as err:
+        exit_with_error(f"Error: {err}", fg="red")
+
+
+
+@PASSW_HARDENING_POLICIES.command(name="digits-class")
+
+@click.argument(
+    "digits-class",
+    nargs=1,
+    required=True,
+)
+@clicommon.pass_db
+def PASSW_HARDENING_POLICIES_digits_class(db, digits_class):
+    """ password digits chars policy """
+
+    table = "PASSW_HARDENING"
+    key = "POLICIES"
+    data = {
+        "digits_class": digits_class,
+    }
+    try:
+        update_entry_validated(db.cfgdb, table, key, data, create_if_not_exists=True)
+    except Exception as err:
+        exit_with_error(f"Error: {err}", fg="red")
+
+
+
+@PASSW_HARDENING_POLICIES.command(name="special-class")
+
+@click.argument(
+    "special-class",
+    nargs=1,
+    required=True,
+)
+@clicommon.pass_db
+def PASSW_HARDENING_POLICIES_special_class(db, special_class):
+    """ password special chars policy """
+
+    table = "PASSW_HARDENING"
+    key = "POLICIES"
+    data = {
+        "special_class": special_class,
+    }
+    try:
+        update_entry_validated(db.cfgdb, table, key, data, create_if_not_exists=True)
+    except Exception as err:
+        exit_with_error(f"Error: {err}", fg="red")
+
+
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+
+def register(cli):
+    """ Register new CLI nodes in root CLI.
+
+    Args:
+        cli: Root CLI node.
+    Raises:
+        Exception: when root CLI already has a command
+                   we are trying to register.
+    """
+    cli_node = PASSW_HARDENING
+    if cli_node.name in cli.commands:
+        raise Exception(f"{cli_node.name} already exists in CLI")
+    cli.add_command(PASSW_HARDENING)