machined: implement user/group lookup varlink API in machined too

Let's natively support our own API in machined too.

This allows us to remove half of nss-mymachines in a later commit.

src/machine/machined-varlink.c

@@ -0,0 +1,404 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include "format-util.h"
+#include "machined-varlink.h"
+#include "mkdir.h"
+#include "user-util.h"
+#include "varlink.h"
+
+typedef struct LookupParameters {
+        const char *user_name;
+        const char *group_name;
+        union {
+                uid_t uid;
+                gid_t gid;
+        };
+        const char *service;
+} LookupParameters;
+
+static int build_user_json(const char *user_name, uid_t uid, const char *real_name, JsonVariant **ret) {
+        assert(user_name);
+        assert(uid_is_valid(uid));
+        assert(ret);
+
+        return json_build(ret, JSON_BUILD_OBJECT(
+                                   JSON_BUILD_PAIR("record", JSON_BUILD_OBJECT(
+                                       JSON_BUILD_PAIR("userName", JSON_BUILD_STRING(user_name)),
+                                       JSON_BUILD_PAIR("uid", JSON_BUILD_UNSIGNED(uid)),
+                                       JSON_BUILD_PAIR("gid", JSON_BUILD_UNSIGNED(GID_NOBODY)),
+                                       JSON_BUILD_PAIR_CONDITION(!isempty(real_name), "realName", JSON_BUILD_STRING(real_name)),
+                                       JSON_BUILD_PAIR("homeDirectory", JSON_BUILD_STRING("/")),
+                                       JSON_BUILD_PAIR("shell", JSON_BUILD_STRING(NOLOGIN)),
+                                       JSON_BUILD_PAIR("locked", JSON_BUILD_BOOLEAN(true)),
+                                       JSON_BUILD_PAIR("service", JSON_BUILD_STRING("io.systemd.Machine")),
+                                       JSON_BUILD_PAIR("disposition", JSON_BUILD_STRING("container"))))));
+}
+
+static bool user_match_lookup_parameters(LookupParameters *p, const char *name, uid_t uid) {
+        assert(p);
+
+        if (p->user_name && !streq(name, p->user_name))
+                return false;
+
+        if (uid_is_valid(p->uid) && uid != p->uid)
+                return false;
+
+        return true;
+}
+
+static int user_lookup_uid(Manager *m, uid_t uid, char **ret_name, char **ret_real_name) {
+        _cleanup_free_ char *n = NULL, *rn = NULL;
+        uid_t converted_uid;
+        Machine *machine;
+        int r;
+
+        assert(m);
+        assert(uid_is_valid(uid));
+        assert(ret_name);
+        assert(ret_real_name);
+
+        if (uid < 0x10000) /* Host UID range */
+                return -ESRCH;
+
+        r = manager_find_machine_for_uid(m, uid, &machine, &converted_uid);
+        if (r < 0)
+                return r;
+        if (!r)
+                return -ESRCH;
+
+        if (asprintf(&n, "vu-%s-" UID_FMT, machine->name, converted_uid) < 0)
+                return -ENOMEM;
+
+        /* Don't synthesize invalid user/group names (too long...) */
+        if (!valid_user_group_name(n, 0))
+                return -ESRCH;
+
+        if (asprintf(&rn, "UID " UID_FMT " of Container %s", converted_uid, machine->name) < 0)
+                return -ENOMEM;
+
+        /* Don't synthesize invalid real names either, but since this field doesn't matter much, simply invalidate things */
+        if (!valid_gecos(rn))
+                rn = mfree(rn);
+
+        *ret_name = TAKE_PTR(n);
+        *ret_real_name = TAKE_PTR(rn);
+        return 0;
+}
+
+static int user_lookup_name(Manager *m, const char *name, uid_t *ret_uid, char **ret_real_name) {
+        _cleanup_free_ char *mn = NULL, *rn = NULL;
+        uid_t uid, converted_uid;
+        Machine *machine;
+        const char *e, *d;
+        int r;
+
+        assert(m);
+
+        if (!valid_user_group_name(name, 0))
+                return -ESRCH;
+
+        e = startswith(name, "vu-");
+        if (!e)
+                return -ESRCH;
+
+        d = strrchr(e, '-');
+        if (!d)
+                return -ESRCH;
+
+        if (parse_uid(d + 1, &uid) < 0)
+                return -ESRCH;
+
+        mn = strndup(e, d - e);
+        if (!mn)
+                return -ENOMEM;
+
+        machine = hashmap_get(m->machines, mn);
+        if (!machine)
+                return -ESRCH;
+
+        if (machine->class != MACHINE_CONTAINER)
+                return -ESRCH;
+
+        r = machine_translate_uid(machine, uid, &converted_uid);
+        if (r < 0)
+                return r;
+
+        if (asprintf(&rn, "UID " UID_FMT " of Container %s", uid, machine->name) < 0)
+                return -ENOMEM;
+        if (!valid_gecos(rn))
+                rn = mfree(rn);
+
+        *ret_uid = converted_uid;
+        *ret_real_name = TAKE_PTR(rn);
+        return 0;
+}
+
+static int vl_method_get_user_record(Varlink *link, JsonVariant *parameters, VarlinkMethodFlags flags, void *userdata) {
+
+        static const JsonDispatch dispatch_table[] = {
+                { "uid",      JSON_VARIANT_UNSIGNED, json_dispatch_uid_gid,      offsetof(LookupParameters, uid),       0         },
+                { "userName", JSON_VARIANT_STRING,   json_dispatch_const_string, offsetof(LookupParameters, user_name), JSON_SAFE },
+                { "service",  JSON_VARIANT_STRING,   json_dispatch_const_string, offsetof(LookupParameters, service),   0         },
+                {}
+        };
+
+        _cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
+        LookupParameters p = {
+                .uid = UID_INVALID,
+        };
+        _cleanup_free_ char *found_name = NULL, *found_real_name = NULL;
+        uid_t found_uid = UID_INVALID, uid;
+        Manager *m = userdata;
+        const char *un;
+        int r;
+
+        assert(parameters);
+        assert(m);
+
+        r = json_dispatch(parameters, dispatch_table, NULL, 0, &p);
+        if (r < 0)
+                return r;
+
+        if (!streq_ptr(p.service, "io.systemd.Machine"))
+                return varlink_error(link, "io.systemd.UserDatabase.BadService", NULL);
+
+        if (uid_is_valid(p.uid))
+                r = user_lookup_uid(m, p.uid, &found_name, &found_real_name);
+        else if (p.user_name)
+                r = user_lookup_name(m, p.user_name, &found_uid, &found_real_name);
+        else
+                return varlink_error(link, "io.systemd.UserDatabase.EnumerationNotSupported", NULL);
+        if (r == -ESRCH)
+                return varlink_error(link, "io.systemd.UserDatabase.NoRecordFound", NULL);
+        if (r < 0)
+                return r;
+
+        uid = uid_is_valid(found_uid) ? found_uid : p.uid;
+        un = found_name ?: p.user_name;
+
+        if (!user_match_lookup_parameters(&p, un, uid))
+                return varlink_error(link, "io.systemd.UserDatabase.ConflictingRecordFound", NULL);
+
+        r = build_user_json(un, uid, found_real_name, &v);
+        if (r < 0)
+                return r;
+
+        return varlink_reply(link, v);
+}
+
+static int build_group_json(const char *group_name, gid_t gid, JsonVariant **ret) {
+        assert(group_name);
+        assert(gid_is_valid(gid));
+        assert(ret);
+
+        return json_build(ret, JSON_BUILD_OBJECT(
+                                   JSON_BUILD_PAIR("record", JSON_BUILD_OBJECT(
+                                       JSON_BUILD_PAIR("groupName", JSON_BUILD_STRING(group_name)),
+                                       JSON_BUILD_PAIR("gid", JSON_BUILD_UNSIGNED(gid)),
+                                       JSON_BUILD_PAIR("service", JSON_BUILD_STRING("io.systemd.Machine")),
+                                       JSON_BUILD_PAIR("disposition", JSON_BUILD_STRING("container"))))));
+    }
+
+static bool group_match_lookup_parameters(LookupParameters *p, const char *name, gid_t gid) {
+        assert(p);
+
+        if (p->group_name && !streq(name, p->group_name))
+                return false;
+
+        if (gid_is_valid(p->gid) && gid != p->gid)
+                return false;
+
+        return true;
+}
+
+static int group_lookup_gid(Manager *m, gid_t gid, char **ret_name) {
+        _cleanup_free_ char *n = NULL;
+        gid_t converted_gid;
+        Machine *machine;
+        int r;
+
+        assert(m);
+        assert(gid_is_valid(gid));
+        assert(ret_name);
+
+        if (gid < 0x10000) /* Host GID range */
+                return -ESRCH;
+
+        r = manager_find_machine_for_gid(m, gid, &machine, &converted_gid);
+        if (r < 0)
+                return r;
+        if (!r)
+                return -ESRCH;
+
+        if (asprintf(&n, "vg-%s-" GID_FMT, machine->name, converted_gid) < 0)
+                return -ENOMEM;
+
+        if (!valid_user_group_name(n, 0))
+                return -ESRCH;
+
+        *ret_name = TAKE_PTR(n);
+        return 0;
+}
+
+static int group_lookup_name(Manager *m, const char *name, gid_t *ret_gid) {
+        _cleanup_free_ char *mn = NULL;
+        gid_t gid, converted_gid;
+        Machine *machine;
+        const char *e, *d;
+        int r;
+
+        assert(m);
+
+        if (!valid_user_group_name(name, 0))
+                return -ESRCH;
+
+        e = startswith(name, "vg-");
+        if (!e)
+                return -ESRCH;
+
+        d = strrchr(e, '-');
+        if (!d)
+                return -ESRCH;
+
+        if (parse_gid(d + 1, &gid) < 0)
+                return -ESRCH;
+
+        mn = strndup(e, d - e);
+        if (!mn)
+                return -ENOMEM;
+
+        machine = hashmap_get(m->machines, mn);
+        if (!mn)
+                return -ESRCH;
+
+        if (machine->class != MACHINE_CONTAINER)
+                return -ESRCH;
+
+        r = machine_translate_gid(machine, gid, &converted_gid);
+        if (r < 0)
+                return r;
+
+        *ret_gid = converted_gid;
+        return 0;
+}
+
+static int vl_method_get_group_record(Varlink *link, JsonVariant *parameters, VarlinkMethodFlags flags, void *userdata) {
+
+        static const JsonDispatch dispatch_table[] = {
+                { "gid",       JSON_VARIANT_UNSIGNED, json_dispatch_uid_gid,      offsetof(LookupParameters, gid),        0         },
+                { "groupName", JSON_VARIANT_STRING,   json_dispatch_const_string, offsetof(LookupParameters, group_name), JSON_SAFE },
+                { "service",   JSON_VARIANT_STRING,   json_dispatch_const_string, offsetof(LookupParameters, service),    0         },
+                {}
+        };
+
+        _cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
+        LookupParameters p = {
+                .gid = GID_INVALID,
+        };
+        _cleanup_free_ char *found_name = NULL;
+        uid_t found_gid = GID_INVALID, gid;
+        Manager *m = userdata;
+        const char *gn;
+        int r;
+
+        assert(parameters);
+        assert(m);
+
+        r = json_dispatch(parameters, dispatch_table, NULL, 0, &p);
+        if (r < 0)
+                return r;
+
+        if (!streq_ptr(p.service, "io.systemd.Machine"))
+                return varlink_error(link, "io.systemd.UserDatabase.BadService", NULL);
+
+        if (gid_is_valid(p.gid))
+                r = group_lookup_gid(m, p.gid, &found_name);
+        else if (p.group_name)
+                r = group_lookup_name(m, p.group_name, (uid_t*) &found_gid);
+        else
+                return varlink_error(link, "io.systemd.UserDatabase.EnumerationNotSupported", NULL);
+        if (r == -ESRCH)
+                return varlink_error(link, "io.systemd.UserDatabase.NoRecordFound", NULL);
+        if (r < 0)
+                return r;
+
+        gid = gid_is_valid(found_gid) ? found_gid : p.gid;
+        gn = found_name ?: p.group_name;
+
+        if (!group_match_lookup_parameters(&p, gn, gid))
+                return varlink_error(link, "io.systemd.UserDatabase.ConflictingRecordFound", NULL);
+
+        r = build_group_json(gn, gid, &v);
+        if (r < 0)
+                return r;
+
+        return varlink_reply(link, v);
+}
+
+static int vl_method_get_memberships(Varlink *link, JsonVariant *parameters, VarlinkMethodFlags flags, void *userdata) {
+
+        static const JsonDispatch dispatch_table[] = {
+                { "userName",  JSON_VARIANT_STRING, json_dispatch_const_string, offsetof(LookupParameters, user_name),  JSON_SAFE },
+                { "groupName", JSON_VARIANT_STRING, json_dispatch_const_string, offsetof(LookupParameters, group_name), JSON_SAFE },
+                { "service",   JSON_VARIANT_STRING, json_dispatch_const_string, offsetof(LookupParameters, service),    0         },
+                {}
+        };
+
+        LookupParameters p = {};
+        int r;
+
+        assert(parameters);
+
+        r = json_dispatch(parameters, dispatch_table, NULL, 0, &p);
+        if (r < 0)
+                return r;
+
+        if (!streq_ptr(p.service, "io.systemd.Machine"))
+                return varlink_error(link, "io.systemd.UserDatabase.BadService", NULL);
+
+        /* We don't support auxiliary groups for machines. */
+        return varlink_error(link, "io.systemd.UserDatabase.NoRecordFound", NULL);
+}
+
+int manager_varlink_init(Manager *m) {
+        _cleanup_(varlink_server_unrefp) VarlinkServer *s = NULL;
+        int r;
+
+        assert(m);
+
+        if (m->varlink_server)
+                return 0;
+
+        r = varlink_server_new(&s, VARLINK_SERVER_ACCOUNT_UID);
+        if (r < 0)
+                return log_error_errno(r, "Failed to allocate varlink server object: %m");
+
+        varlink_server_set_userdata(s, m);
+
+        r = varlink_server_bind_method_many(
+                        s,
+                        "io.systemd.UserDatabase.GetUserRecord",  vl_method_get_user_record,
+                        "io.systemd.UserDatabase.GetGroupRecord", vl_method_get_group_record,
+                        "io.systemd.UserDatabase.GetMemberships", vl_method_get_memberships);
+        if (r < 0)
+                return log_error_errno(r, "Failed to register varlink methods: %m");
+
+        (void) mkdir_p("/run/systemd/userdb", 0755);
+
+        r = varlink_server_listen_address(s, "/run/systemd/userdb/io.systemd.Machine", 0666);
+        if (r < 0)
+                return log_error_errno(r, "Failed to bind to varlink socket: %m");
+
+        r = varlink_server_attach_event(s, m->event, SD_EVENT_PRIORITY_NORMAL);
+        if (r < 0)
+                return log_error_errno(r, "Failed to attach varlink connection to event loop: %m");
+
+        m->varlink_server = TAKE_PTR(s);
+        return 0;
+}
+
+void manager_varlink_done(Manager *m) {
+        assert(m);
+
+        m->varlink_server = varlink_server_unref(m->varlink_server);
+}

src/machine/machined-varlink.h

@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+#pragma once
+
+#include "machined.h"
+
+int manager_varlink_init(Manager *m);
+void manager_varlink_done(Manager *m);

src/machine/machined.c

@@ -20,6 +20,7 @@
 #include "hostname-util.h"
 #include "label.h"
 #include "machine-image.h"
+#include "machined-varlink.h"
 #include "machined.h"
 #include "main-func.h"
 #include "process-util.h"
@@ -86,6 +87,8 @@ static Manager* manager_unref(Manager *m) {
 
         bus_verify_polkit_async_registry_free(m->polkit_registry);
 
+        manager_varlink_done(m);
+
         sd_bus_flush_close_unref(m->bus);
         sd_event_unref(m->event);
 
@@ -272,6 +275,11 @@ static int manager_startup(Manager *m) {
         if (r < 0)
                 return r;
 
+        /* Set up Varlink service */
+        r = manager_varlink_init(m);
+        if (r < 0)
+                return r;
+
         /* Deserialize state */
         manager_enumerate_machines(m);
 
@@ -291,6 +299,9 @@ static bool check_idle(void *userdata) {
         if (m->operations)
                 return false;
 
+        if (varlink_server_current_connections(m->varlink_server) > 0)
+                return false;
+
         manager_gc(m, true);
 
         return hashmap_isempty(m->machines);

src/machine/machined.h

@@ -14,6 +14,7 @@ typedef struct Manager Manager;
 #include "machine-dbus.h"
 #include "machine.h"
 #include "operation.h"
+#include "varlink.h"
 
 struct Manager {
         sd_event *event;
@@ -36,6 +37,8 @@ struct Manager {
         unsigned n_operations;
 
         sd_event_source *nscd_cache_flush_event;
+
+        VarlinkServer *varlink_server;
 };
 
 int manager_add_machine(Manager *m, const char *name, Machine **_machine);

src/machine/meson.build

@@ -6,14 +6,16 @@ systemd_machined_sources = files('''
 '''.split())
 
 libmachine_core_sources = files('''
-        machine.c
-        machine.h
-        machined-dbus.c
-        machined-core.c
-        machine-dbus.c
-        machine-dbus.h
         image-dbus.c
         image-dbus.h
+        machine-dbus.c
+        machine-dbus.h
+        machine.c
+        machine.h
+        machined-core.c
+        machined-dbus.c
+        machined-varlink.c
+        machined-varlink.h
         operation.c
         operation.h
 '''.split())