src/shared/varlink.h

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2 #pragma once
   3
   4 #include "sd-event.h"
   5
   6 #include "json.h"
   7 #include "pidref.h"
   8 #include "time-util.h"
   9 #include "varlink-idl.h"
  10
  11 /* A minimal Varlink implementation. We only implement the minimal, obvious bits here though. No validation,
  12  * no introspection, no name service, just the stuff actually needed.
  13  *
  14  * You might wonder why we aren't using libvarlink here? Varlink is a very simple protocol, which allows us
  15  * to write our own implementation relatively easily. However, the main reasons are these:
  16  *
  17  * • We want to use our own JSON subsystem, with all the benefits that brings (i.e. accurate unsigned+signed
  18  *   64-bit integers, full fuzzing, logging during parsing and so on). If we'd want to use that with
  19  *   libvarlink we'd have to serialize and deserialize all the time from its own representation which is
  20  *   inefficient and nasty.
  21  *
  22  * • We want integration into sd-event, but also synchronous event-loop-less operation
  23  *
  24  * • We need proper per-UID accounting and access control, since we want to allow communication between
  25  *   unprivileged clients and privileged servers.
  26  *
  27  * • And of course, we don't want the name service and introspection stuff for now (though that might
  28  *   change).
  29  */
  30
  31 typedef struct Varlink Varlink;
  32 typedef struct VarlinkServer VarlinkServer;
  33
  34 typedef enum VarlinkReplyFlags {
  35         VARLINK_REPLY_ERROR     = 1 << 0,
  36         VARLINK_REPLY_CONTINUES = 1 << 1,
  37         VARLINK_REPLY_LOCAL     = 1 << 2,
  38 } VarlinkReplyFlags;
  39
  40 typedef enum VarlinkMethodFlags {
  41         VARLINK_METHOD_ONEWAY = 1 << 0,
  42         VARLINK_METHOD_MORE   = 2 << 1,
  43 } VarlinkMethodFlags;
  44
  45 typedef enum VarlinkServerFlags {
  46         VARLINK_SERVER_ROOT_ONLY        = 1 << 0, /* Only accessible by root */
  47         VARLINK_SERVER_MYSELF_ONLY      = 1 << 1, /* Only accessible by our own UID */
  48         VARLINK_SERVER_ACCOUNT_UID      = 1 << 2, /* Do per user accounting */
  49         VARLINK_SERVER_INHERIT_USERDATA = 1 << 3, /* Initialize Varlink connection userdata from VarlinkServer userdata */
  50         _VARLINK_SERVER_FLAGS_ALL = (1 << 4) - 1,
  51 } VarlinkServerFlags;
  52
  53 typedef int (*VarlinkMethod)(Varlink *link, JsonVariant *parameters, VarlinkMethodFlags flags, void *userdata);
  54 typedef int (*VarlinkReply)(Varlink *link, JsonVariant *parameters, const char *error_id, VarlinkReplyFlags flags, void *userdata);
  55 typedef int (*VarlinkConnect)(VarlinkServer *server, Varlink *link, void *userdata);
  56 typedef void (*VarlinkDisconnect)(VarlinkServer *server, Varlink *link, void *userdata);
  57
  58 int varlink_connect_address(Varlink **ret, const char *address);
  59 int varlink_connect_exec(Varlink **ret, const char *command, char **argv);
  60 int varlink_connect_url(Varlink **ret, const char *url);
  61 int varlink_connect_fd(Varlink **ret, int fd);
  62
  63 Varlink* varlink_ref(Varlink *link);
  64 Varlink* varlink_unref(Varlink *v);
  65
  66 int varlink_get_fd(Varlink *v);
  67 int varlink_get_events(Varlink *v);
  68 int varlink_get_timeout(Varlink *v, usec_t *ret);
  69
  70 int varlink_attach_event(Varlink *v, sd_event *e, int64_t priority);
  71 void varlink_detach_event(Varlink *v);
  72 sd_event *varlink_get_event(Varlink *v);
  73
  74 int varlink_process(Varlink *v);
  75 int varlink_wait(Varlink *v, usec_t timeout);
  76
  77 int varlink_is_idle(Varlink *v);
  78
  79 int varlink_flush(Varlink *v);
  80 int varlink_close(Varlink *v);
  81
  82 Varlink* varlink_flush_close_unref(Varlink *v);
  83 Varlink* varlink_close_unref(Varlink *v);
  84
  85 /* Enqueue method call, not expecting a reply */
  86 int varlink_send(Varlink *v, const char *method, JsonVariant *parameters);
  87 int varlink_sendb(Varlink *v, const char *method, ...);
  88
  89 /* Send method call and wait for reply */
  90 int varlink_call(Varlink *v, const char *method, JsonVariant *parameters, JsonVariant **ret_parameters, const char **ret_error_id, VarlinkReplyFlags *ret_flags);
  91 int varlink_callb(Varlink *v, const char *method, JsonVariant **ret_parameters, const char **ret_error_id, VarlinkReplyFlags *ret_flags, ...);
  92
  93 /* Send method call and begin collecting all 'more' replies into an array, finishing when a final reply is sent */
  94 int varlink_collect(Varlink *v, const char *method, JsonVariant *parameters, JsonVariant **ret_parameters, const char **ret_error_id, VarlinkReplyFlags *ret_flags);
  95 int varlink_collectb(Varlink *v, const char *method, JsonVariant **ret_parameters, const char **ret_error_id, VarlinkReplyFlags *ret_flags, ...);
  96
  97 /* Enqueue method call, expect a reply, which is eventually delivered to the reply callback */
  98 int varlink_invoke(Varlink *v, const char *method, JsonVariant *parameters);
  99 int varlink_invokeb(Varlink *v, const char *method, ...);
 100
 101 /* Enqueue method call, expect a reply now, and possibly more later, which are all delivered to the reply callback */
 102 int varlink_observe(Varlink *v, const char *method, JsonVariant *parameters);
 103 int varlink_observeb(Varlink *v, const char *method, ...);
 104
 105 /* Enqueue a final reply */
 106 int varlink_reply(Varlink *v, JsonVariant *parameters);
 107 int varlink_replyb(Varlink *v, ...);
 108
 109 /* Enqueue a (final) error */
 110 int varlink_error(Varlink *v, const char *error_id, JsonVariant *parameters);
 111 int varlink_errorb(Varlink *v, const char *error_id, ...);
 112 int varlink_error_invalid_parameter(Varlink *v, JsonVariant *parameters);
 113 int varlink_error_invalid_parameter_name(Varlink *v, const char *name);
 114 int varlink_error_errno(Varlink *v, int error);
 115
 116 /* Enqueue a "more" reply */
 117 int varlink_notify(Varlink *v, JsonVariant *parameters);
 118 int varlink_notifyb(Varlink *v, ...);
 119
 120 /* Ask for the current message to be dispatched again */
 121 int varlink_dispatch_again(Varlink *v);
 122
 123 /* Get the currently processed incoming message */
 124 int varlink_get_current_parameters(Varlink *v, JsonVariant **ret);
 125
 126 /* Parsing incoming data via json_dispatch() and generate a nice error on parse errors */
 127 int varlink_dispatch(Varlink *v, JsonVariant *parameters, const JsonDispatch table[], void *userdata);
 128
 129 /* Write outgoing fds into the socket (to be associated with the next enqueued message) */
 130 int varlink_push_fd(Varlink *v, int fd);
 131 int varlink_dup_fd(Varlink *v, int fd);
 132 int varlink_reset_fds(Varlink *v);
 133
 134 /* Read incoming fds from the socket (associated with the currently handled message) */
 135 int varlink_peek_fd(Varlink *v, size_t i);
 136 int varlink_take_fd(Varlink *v, size_t i);
 137
 138 int varlink_set_allow_fd_passing_input(Varlink *v, bool b);
 139 int varlink_set_allow_fd_passing_output(Varlink *v, bool b);
 140
 141 /* Bind a disconnect, reply or timeout callback */
 142 int varlink_bind_reply(Varlink *v, VarlinkReply reply);
 143
 144 void* varlink_set_userdata(Varlink *v, void *userdata);
 145 void* varlink_get_userdata(Varlink *v);
 146
 147 int varlink_get_peer_uid(Varlink *v, uid_t *ret);
 148 int varlink_get_peer_pid(Varlink *v, pid_t *ret);
 149 int varlink_get_peer_pidref(Varlink *v, PidRef *ret);
 150
 151 int varlink_set_relative_timeout(Varlink *v, usec_t usec);
 152
 153 VarlinkServer* varlink_get_server(Varlink *v);
 154
 155 int varlink_set_description(Varlink *v, const char *d);
 156
 157 /* Create a varlink server */
 158 int varlink_server_new(VarlinkServer **ret, VarlinkServerFlags flags);
 159 VarlinkServer *varlink_server_ref(VarlinkServer *s);
 160 VarlinkServer *varlink_server_unref(VarlinkServer *s);
 161
 162 /* Add addresses or fds to listen on */
 163 int varlink_server_listen_address(VarlinkServer *s, const char *address, mode_t mode);
 164 int varlink_server_listen_fd(VarlinkServer *s, int fd);
 165 int varlink_server_listen_auto(VarlinkServer *s);
 166 int varlink_server_add_connection(VarlinkServer *s, int fd, Varlink **ret);
 167
 168 /* Bind callbacks */
 169 int varlink_server_bind_method(VarlinkServer *s, const char *method, VarlinkMethod callback);
 170 int varlink_server_bind_method_many_internal(VarlinkServer *s, ...);
 171 #define varlink_server_bind_method_many(s, ...) varlink_server_bind_method_many_internal(s, __VA_ARGS__, NULL)
 172 int varlink_server_bind_connect(VarlinkServer *s, VarlinkConnect connect);
 173 int varlink_server_bind_disconnect(VarlinkServer *s, VarlinkDisconnect disconnect);
 174
 175 /* Add interface definition */
 176 int varlink_server_add_interface(VarlinkServer *s, const VarlinkInterface *interface);
 177 int varlink_server_add_interface_many_internal(VarlinkServer *s, ...);
 178 #define varlink_server_add_interface_many(s, ...) varlink_server_add_interface_many_internal(s, __VA_ARGS__, NULL)
 179
 180 void* varlink_server_set_userdata(VarlinkServer *s, void *userdata);
 181 void* varlink_server_get_userdata(VarlinkServer *s);
 182
 183 int varlink_server_attach_event(VarlinkServer *v, sd_event *e, int64_t priority);
 184 int varlink_server_detach_event(VarlinkServer *v);
 185 sd_event *varlink_server_get_event(VarlinkServer *v);
 186
 187 int varlink_server_loop_auto(VarlinkServer *server);
 188
 189 int varlink_server_shutdown(VarlinkServer *server);
 190
 191 int varlink_server_set_exit_on_idle(VarlinkServer *s, bool b);
 192
 193 unsigned varlink_server_connections_max(VarlinkServer *s);
 194 unsigned varlink_server_connections_per_uid_max(VarlinkServer *s);
 195
 196 int varlink_server_set_connections_per_uid_max(VarlinkServer *s, unsigned m);
 197 int varlink_server_set_connections_max(VarlinkServer *s, unsigned m);
 198
 199 unsigned varlink_server_current_connections(VarlinkServer *s);
 200
 201 int varlink_server_set_description(VarlinkServer *s, const char *description);
 202
 203 typedef enum VarlinkInvocationFlags {
 204         VARLINK_ALLOW_LISTEN                     = 1 << 0,
 205         VARLINK_ALLOW_ACCEPT                     = 1 << 1,
 206         _VARLINK_SERVER_INVOCATION_FLAGS_MAX     = (1 << 2) - 1,
 207         _VARLINK_SERVER_INVOCATION_FLAGS_INVALID = -EINVAL,
 208 } VarlinkInvocationFlags;
 209
 210 int varlink_invocation(VarlinkInvocationFlags flags);
 211
 212 DEFINE_TRIVIAL_CLEANUP_FUNC(Varlink *, varlink_unref);
 213 DEFINE_TRIVIAL_CLEANUP_FUNC(Varlink *, varlink_close_unref);
 214 DEFINE_TRIVIAL_CLEANUP_FUNC(Varlink *, varlink_flush_close_unref);
 215 DEFINE_TRIVIAL_CLEANUP_FUNC(VarlinkServer *, varlink_server_unref);
 216
 217 /* These are local errors that never cross the wire, and are our own invention */
 218 #define VARLINK_ERROR_DISCONNECTED "io.systemd.Disconnected"
 219 #define VARLINK_ERROR_TIMEOUT "io.systemd.TimedOut"
 220 #define VARLINK_ERROR_PROTOCOL "io.systemd.Protocol"
 221
 222 /* This one we invented, and use for generically propagating system errors (errno) to clients */
 223 #define VARLINK_ERROR_SYSTEM "io.systemd.System"
 224
 225 /* This one we invented and is a weaker version of "org.varlink.service.PermissionDenied", and indicates that if user would allow interactive auth, we might allow access */
 226 #define VARLINK_ERROR_INTERACTIVE_AUTHENTICATION_REQUIRED "io.systemd.InteractiveAuthenticationRequired"
 227
 228 /* These are errors defined in the Varlink spec */
 229 #define VARLINK_ERROR_INTERFACE_NOT_FOUND "org.varlink.service.InterfaceNotFound"
 230 #define VARLINK_ERROR_METHOD_NOT_FOUND "org.varlink.service.MethodNotFound"
 231 #define VARLINK_ERROR_METHOD_NOT_IMPLEMENTED "org.varlink.service.MethodNotImplemented"
 232 #define VARLINK_ERROR_INVALID_PARAMETER "org.varlink.service.InvalidParameter"
 233 #define VARLINK_ERROR_PERMISSION_DENIED "org.varlink.service.PermissionDenied"
 234 #define VARLINK_ERROR_EXPECTED_MORE "org.varlink.service.ExpectedMore"