pve-access-control/src/PVE/API2/ACL.pm
Fabian Grünbichler 46bfd59dfc acls: restrict less-privileged ACL modifications
there are currently three possibilities to modify ACLs without the
'Permissions.Modify' privilege in PVE::RPCEnvironment::check_perm_modify:

    if ($path =~ m|^/storage/.+$|) {
	push @$testperms, 'Datastore.Allocate';
    } elsif ($path =~ m|^/vms/.+$|) {
	push @$testperms, 'VM.Allocate';
    } elsif ($path =~ m|^/pool/.+$|) {
	push @$testperms, 'Pool.Allocate';
    }

lock those down by only allowing the currently authenticated user to hand out a
subset of their own privileges, never more.

for example, this still allows a PVEVMAdmin to create ACLs for other
users/tokens with PVEVMUser (on '/vm/XXX'), but not with Administrator or
PVEPermAdmin.

Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
2023-06-07 11:13:16 +02:00

232 lines
6.5 KiB
Perl

package PVE::API2::ACL;
use strict;
use warnings;
use PVE::Cluster qw (cfs_read_file cfs_write_file);
use PVE::Tools qw(split_list);
use PVE::AccessControl;
use PVE::Exception qw(raise_param_exc);
use PVE::JSONSchema qw(get_standard_option register_standard_option);
use PVE::SafeSyslog;
use PVE::RESTHandler;
use base qw(PVE::RESTHandler);
register_standard_option('acl-propagate', {
description => "Allow to propagate (inherit) permissions.",
type => 'boolean',
optional => 1,
default => 1,
});
register_standard_option('acl-path', {
description => "Access control path",
type => 'string',
});
__PACKAGE__->register_method ({
name => 'read_acl',
path => '',
method => 'GET',
description => "Get Access Control List (ACLs).",
permissions => {
description => "The returned list is restricted to objects where you have rights to modify permissions.",
user => 'all',
},
parameters => {
additionalProperties => 0,
properties => {},
},
returns => {
type => 'array',
items => {
type => "object",
additionalProperties => 0,
properties => {
propagate => get_standard_option('acl-propagate'),
path => get_standard_option('acl-path'),
type => { type => 'string', enum => ['user', 'group', 'token'] },
ugid => { type => 'string' },
roleid => { type => 'string' },
},
},
},
code => sub {
my ($param) = @_;
my $rpcenv = PVE::RPCEnvironment::get();
my $authuser = $rpcenv->get_user();
my $res = [];
my $usercfg = $rpcenv->{user_cfg};
if (!$usercfg || !$usercfg->{acl_root}) {
return $res;
}
my $audit = $rpcenv->check($authuser, '/access', ['Sys.Audit'], 1);
my $root = $usercfg->{acl_root};
PVE::AccessControl::iterate_acl_tree("/", $root, sub {
my ($path, $node) = @_;
foreach my $type (qw(user group token)) {
my $d = $node->{"${type}s"};
next if !$d;
next if !($audit || $rpcenv->check_perm_modify($authuser, $path, 1));
foreach my $id (keys %$d) {
foreach my $role (keys %{$d->{$id}}) {
my $propagate = $d->{$id}->{$role};
push @$res, {
path => $path,
type => $type,
ugid => $id,
roleid => $role,
propagate => $propagate,
};
}
}
}
});
return $res;
}});
__PACKAGE__->register_method ({
name => 'update_acl',
protected => 1,
path => '',
method => 'PUT',
permissions => {
check => ['perm-modify', '{path}'],
},
description => "Update Access Control List (add or remove permissions).",
parameters => {
additionalProperties => 0,
properties => {
propagate => get_standard_option('acl-propagate'),
path => get_standard_option('acl-path'),
users => {
description => "List of users.",
type => 'string', format => 'pve-userid-list',
optional => 1,
},
groups => {
description => "List of groups.",
type => 'string', format => 'pve-groupid-list',
optional => 1,
},
tokens => {
description => "List of API tokens.",
type => 'string', format => 'pve-tokenid-list',
optional => 1,
},
roles => {
description => "List of roles.",
type => 'string', format => 'pve-roleid-list',
},
delete => {
description => "Remove permissions (instead of adding it).",
type => 'boolean',
optional => 1,
},
},
},
returns => { type => 'null' },
code => sub {
my ($param) = @_;
if (!($param->{users} || $param->{groups} || $param->{tokens})) {
raise_param_exc({ map { $_ => "either 'users', 'groups' or 'tokens' is required." } qw(users groups tokens) });
}
my $path = PVE::AccessControl::normalize_path($param->{path});
raise_param_exc({ path => "invalid ACL path '$param->{path}'" }) if !$path;
if (!$param->{delete} && !PVE::AccessControl::check_path($path)) {
raise_param_exc({ path => "invalid ACL path '$param->{path}'" });
}
PVE::AccessControl::lock_user_config(
sub {
my $cfg = cfs_read_file("user.cfg");
my $rpcenv = PVE::RPCEnvironment::get();
my $authuser = $rpcenv->get_user();
my $auth_user_privs = $rpcenv->permissions($authuser, $path);
my $propagate = 1;
if (defined($param->{propagate})) {
$propagate = $param->{propagate} ? 1 : 0;
}
my $node = PVE::AccessControl::find_acl_tree_node($cfg->{acl_root}, $path);
foreach my $role (split_list($param->{roles})) {
die "role '$role' does not exist\n"
if !$cfg->{roles}->{$role};
if (!$auth_user_privs->{'Permissions.Modify'}) {
# 'perm-modify' allows /vms/* with VM.Allocate and similar restricted use cases
# filter those to only allow handing out a subset of currently active privs
my $role_privs = $cfg->{roles}->{$role};
my $verb = $param->{delete} ? 'remove' : 'add';
foreach my $priv (keys $role_privs->%*) {
raise_param_exc({ role => "Cannot $verb role '$role' - requires 'Permissions.Modify' or superset of privileges." })
if !defined($auth_user_privs->{$priv});
# propagation is only potentially problematic for adding ACLs, not removing..
raise_param_exc({ role => "Cannot $verb role '$role' with propagation - requires 'Permissions.Modify' or propagated superset of privileges." })
if $propagate && $auth_user_privs->{$priv} != $propagate && !$param->{delete};
}
# NoAccess has no privs, needs an explicit check
raise_param_exc({ role => "Cannot $verb role '$role' - requires 'Permissions.Modify'"})
if $role eq 'NoAccess';
}
foreach my $group (split_list($param->{groups})) {
die "group '$group' does not exist\n"
if !$cfg->{groups}->{$group};
if ($param->{delete}) {
delete($node->{groups}->{$group}->{$role});
} else {
$node->{groups}->{$group}->{$role} = $propagate;
}
}
foreach my $userid (split_list($param->{users})) {
my $username = PVE::AccessControl::verify_username($userid);
die "user '$username' does not exist\n"
if !$cfg->{users}->{$username};
if ($param->{delete}) {
delete ($node->{users}->{$username}->{$role});
} else {
$node->{users}->{$username}->{$role} = $propagate;
}
}
foreach my $tokenid (split_list($param->{tokens})) {
my ($username, $token) = PVE::AccessControl::split_tokenid($tokenid);
PVE::AccessControl::check_token_exist($cfg, $username, $token);
if ($param->{delete}) {
delete $node->{tokens}->{$tokenid}->{$role};
} else {
$node->{tokens}->{$tokenid}->{$role} = $propagate;
}
}
}
cfs_write_file("user.cfg", $cfg);
}, "ACL update failed");
return undef;
}});
1;