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Merge pull request #8368 from yuwata/nss-systemd-getpwent

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nss-systemd: make dynamic users enumerable by `getent`
This commit is contained in:
Lennart Poettering 2018-03-21 12:36:47 +01:00 committed by GitHub
commit 0ba6791f46
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GPG Key ID: 4AEE18F83AFDEB23
7 changed files with 452 additions and 77 deletions
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3
TODO
View File

@ -27,9 +27,6 @@ Features:
* add proper dbus APIs for the various sd_notify() commands, such as MAINPID=1
and so on, which would mean we could report errors and such.
* nss-systemd: implement enumeration, that shows all dynamic users plus the
synthesized ones if necessary, so that "getent passwd" shows useful data.
* teach tmpfiles.d q/Q logic something sensible in the context of XFS/ext4
project quota

45
src/core/dbus-manager.c
View File

@ -1798,6 +1798,50 @@ static int method_lookup_dynamic_user_by_uid(sd_bus_message *message, void *user
return sd_bus_reply_method_return(message, "s", name);
}
static int method_get_dynamic_users(sd_bus_message *message, void *userdata, sd_bus_error *error) {
_cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
Manager *m = userdata;
DynamicUser *d;
Iterator i;
int r;
assert(message);
assert(m);
assert_cc(sizeof(uid_t) == sizeof(uint32_t));
if (!MANAGER_IS_SYSTEM(m))
return sd_bus_error_setf(error, SD_BUS_ERROR_NOT_SUPPORTED, "Dynamic users are only supported in the system instance.");
r = sd_bus_message_new_method_return(message, &reply);
if (r < 0)
return r;
r = sd_bus_message_open_container(reply, 'a', "(us)");
if (r < 0)
return r;
HASHMAP_FOREACH(d, m->dynamic_users, i) {
uid_t uid;
r = dynamic_user_current(d, &uid);
if (r == -EAGAIN) /* not realized yet? */
continue;
if (r < 0)
return sd_bus_error_setf(error, SD_BUS_ERROR_FAILED, "Failed to lookup a dynamic user.");
r = sd_bus_message_append(reply, "(us)", uid, d->name);
if (r < 0)
return r;
}
r = sd_bus_message_close_container(reply);
if (r < 0)
return r;
return sd_bus_send(NULL, reply, NULL);
}
static int list_unit_files_by_patterns(sd_bus_message *message, void *userdata, sd_bus_error *error, char **states, char **patterns) {
_cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
Manager *m = userdata;
@ -2572,6 +2616,7 @@ const sd_bus_vtable bus_manager_vtable[] = {
SD_BUS_METHOD("SetExitCode", "y", NULL, method_set_exit_code, SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_METHOD("LookupDynamicUserByName", "s", "u", method_lookup_dynamic_user_by_name, SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_METHOD("LookupDynamicUserByUID", "u", "s", method_lookup_dynamic_user_by_uid, SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_METHOD("GetDynamicUsers", NULL, "a(us)", method_get_dynamic_users, SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_SIGNAL("UnitNew", "so", 0),
SD_BUS_SIGNAL("UnitRemoved", "so", 0),

2
src/core/dynamic-user.c
View File

@ -563,7 +563,7 @@ static int dynamic_user_realize(
return 0;
}
static int dynamic_user_current(DynamicUser *d, uid_t *ret) {
int dynamic_user_current(DynamicUser *d, uid_t *ret) {
_cleanup_(unlockfp) int storage_socket0_lock = -1;
_cleanup_close_ int lock_fd = -1;
uid_t uid;

1
src/core/dynamic-user.h
View File

@ -48,6 +48,7 @@ int dynamic_user_serialize(Manager *m, FILE *f, FDSet *fds);
void dynamic_user_deserialize_one(Manager *m, const char *value, FDSet *fds);
void dynamic_user_vacuum(Manager *m, bool close_user);
int dynamic_user_current(DynamicUser *d, uid_t *ret);
int dynamic_user_lookup_uid(Manager *m, uid_t uid, char **ret);
int dynamic_user_lookup_name(Manager *m, const char *name, uid_t *ret);

4
src/core/org.freedesktop.systemd1.conf
View File

@ -140,6 +140,10 @@
send_interface="org.freedesktop.systemd1.Manager"
send_member="LookupDynamicUserByUID"/>
<allow send_destination="org.freedesktop.systemd1"
send_interface="org.freedesktop.systemd1.Manager"
send_member="GetDynamicUsers"/>
<!-- Completely open to anyone: org.freedesktop.systemd1.Unit interface -->
<allow send_destination="org.freedesktop.systemd1"

468
src/nss-systemd/nss-systemd.c
View File

@ -19,13 +19,17 @@
***/
#include <nss.h>
#include <pthread.h>
#include "sd-bus.h"
#include "alloc-util.h"
#include "bus-common-errors.h"
#include "dirent-util.h"
#include "env-util.h"
#include "fd-util.h"
#include "fs-util.h"
#include "list.h"
#include "macro.h"
#include "nss-util.h"
#include "signal-util.h"
@ -34,6 +38,11 @@
#include "user-util.h"
#include "util.h"
#define DYNAMIC_USER_GECOS "Dynamic User"
#define DYNAMIC_USER_PASSWD "*" /* locked */
#define DYNAMIC_USER_DIR "/"
#define DYNAMIC_USER_SHELL "/sbin/nologin"
static const struct passwd root_passwd = {
.pw_name = (char*) "root",
.pw_passwd = (char*) "x", /* see shadow file */
@ -68,8 +77,40 @@ static const struct group nobody_group = {
.gr_mem = (char*[]) { NULL },
};
typedef struct UserEntry UserEntry;
typedef struct GetentData GetentData;
struct UserEntry {
uid_t id;
char *name;
GetentData *data;
LIST_FIELDS(UserEntry, entries);
};
struct GetentData {
/* As explained in NOTES section of getpwent_r(3) as 'getpwent_r() is not really
* reentrant since it shares the reading position in the stream with all other threads',
* we need to protect the data in UserEntry from multithreaded programs which may call
* setpwent(), getpwent_r(), or endpwent() simultaneously. So, each function locks the
* data by using the mutex below. */
pthread_mutex_t mutex;
UserEntry *position;
LIST_HEAD(UserEntry, entries);
};
static GetentData getpwent_data = { PTHREAD_MUTEX_INITIALIZER, NULL, NULL };
static GetentData getgrent_data = { PTHREAD_MUTEX_INITIALIZER, NULL, NULL };
NSS_GETPW_PROTOTYPES(systemd);
NSS_GETGR_PROTOTYPES(systemd);
enum nss_status _nss_systemd_endpwent(void) _public_;
enum nss_status _nss_systemd_setpwent(int stayopen) _public_;
enum nss_status _nss_systemd_getpwent_r(struct passwd *result, char *buffer, size_t buflen, int *errnop) _public_;
enum nss_status _nss_systemd_endgrent(void) _public_;
enum nss_status _nss_systemd_setgrent(int stayopen) _public_;
enum nss_status _nss_systemd_getgrent_r(struct group *result, char *buffer, size_t buflen, int *errnop) _public_;
static int direct_lookup_name(const char *name, uid_t *ret) {
_cleanup_free_ char *s = NULL;
@ -115,6 +156,9 @@ enum nss_status _nss_systemd_getpwnam_r(
char *buffer, size_t buflen,
int *errnop) {
_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
_cleanup_(sd_bus_message_unrefp) sd_bus_message* reply = NULL;
_cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
uint32_t translated;
size_t l;
int bypass, r;
@ -150,16 +194,18 @@ enum nss_status _nss_systemd_getpwnam_r(
bypass = getenv_bool_secure("SYSTEMD_NSS_BYPASS_BUS");
if (bypass <= 0) {
_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
_cleanup_(sd_bus_message_unrefp) sd_bus_message* reply = NULL;
_cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
r = sd_bus_open_system(&bus);
if (r < 0) {
if (r < 0)
bypass = 1;
goto direct_lookup;
}
}
if (bypass > 0) {
r = direct_lookup_name(name, (uid_t*) &translated);
if (r == -ENOENT)
goto not_found;
if (r < 0)
goto fail;
} else {
r = sd_bus_call_method(bus,
"org.freedesktop.systemd1",
"/org/freedesktop/systemd1",
@ -181,16 +227,6 @@ enum nss_status _nss_systemd_getpwnam_r(
goto fail;
}
direct_lookup:
if (bypass > 0) {
/* Access the dynamic UID allocation directly if we are called from dbus-daemon, see above. */
r = direct_lookup_name(name, (uid_t*) &translated);
if (r == -ENOENT)
goto not_found;
if (r < 0)
goto fail;
}
l = strlen(name);
if (buflen < l+1) {
*errnop = ERANGE;
@ -202,10 +238,10 @@ direct_lookup:
pwd->pw_name = buffer;
pwd->pw_uid = (uid_t) translated;
pwd->pw_gid = (uid_t) translated;
pwd->pw_gecos = (char*) "Dynamic User";
pwd->pw_passwd = (char*) "*"; /* locked */
pwd->pw_dir = (char*) "/";
pwd->pw_shell = (char*) "/sbin/nologin";
pwd->pw_gecos = (char*) DYNAMIC_USER_GECOS;
pwd->pw_passwd = (char*) DYNAMIC_USER_PASSWD;
pwd->pw_dir = (char*) DYNAMIC_USER_DIR;
pwd->pw_shell = (char*) DYNAMIC_USER_SHELL;
*errnop = 0;
return NSS_STATUS_SUCCESS;
@ -262,11 +298,20 @@ enum nss_status _nss_systemd_getpwuid_r(
bypass = getenv_bool_secure("SYSTEMD_NSS_BYPASS_BUS");
if (bypass <= 0) {
r = sd_bus_open_system(&bus);
if (r < 0) {
if (r < 0)
bypass = 1;
goto direct_lookup;
}
}
if (bypass > 0) {
r = direct_lookup_uid(uid, &direct);
if (r == -ENOENT)
goto not_found;
if (r < 0)
goto fail;
translated = direct;
} else {
r = sd_bus_call_method(bus,
"org.freedesktop.systemd1",
"/org/freedesktop/systemd1",
@ -288,18 +333,6 @@ enum nss_status _nss_systemd_getpwuid_r(
goto fail;
}
direct_lookup:
if (bypass > 0) {
r = direct_lookup_uid(uid, &direct);
if (r == -ENOENT)
goto not_found;
if (r < 0)
goto fail;
translated = direct;
}
l = strlen(translated) + 1;
if (buflen < l) {
*errnop = ERANGE;
@ -311,10 +344,10 @@ direct_lookup:
pwd->pw_name = buffer;
pwd->pw_uid = uid;
pwd->pw_gid = uid;
pwd->pw_gecos = (char*) "Dynamic User";
pwd->pw_passwd = (char*) "*"; /* locked */
pwd->pw_dir = (char*) "/";
pwd->pw_shell = (char*) "/sbin/nologin";
pwd->pw_gecos = (char*) DYNAMIC_USER_GECOS;
pwd->pw_passwd = (char*) DYNAMIC_USER_PASSWD;
pwd->pw_dir = (char*) DYNAMIC_USER_DIR;
pwd->pw_shell = (char*) DYNAMIC_USER_SHELL;
*errnop = 0;
return NSS_STATUS_SUCCESS;
@ -336,6 +369,9 @@ enum nss_status _nss_systemd_getgrnam_r(
char *buffer, size_t buflen,
int *errnop) {
_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
_cleanup_(sd_bus_message_unrefp) sd_bus_message* reply = NULL;
_cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
uint32_t translated;
size_t l;
int bypass, r;
@ -368,16 +404,18 @@ enum nss_status _nss_systemd_getgrnam_r(
bypass = getenv_bool_secure("SYSTEMD_NSS_BYPASS_BUS");
if (bypass <= 0) {
_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
_cleanup_(sd_bus_message_unrefp) sd_bus_message* reply = NULL;
_cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
r = sd_bus_open_system(&bus);
if (r < 0) {
if (r < 0)
bypass = 1;
goto direct_lookup;
}
}
if (bypass > 0) {
r = direct_lookup_name(name, (uid_t*) &translated);
if (r == -ENOENT)
goto not_found;
if (r < 0)
goto fail;
} else {
r = sd_bus_call_method(bus,
"org.freedesktop.systemd1",
"/org/freedesktop/systemd1",
@ -399,16 +437,6 @@ enum nss_status _nss_systemd_getgrnam_r(
goto fail;
}
direct_lookup:
if (bypass > 0) {
/* Access the dynamic GID allocation directly if we are called from dbus-daemon, see above. */
r = direct_lookup_name(name, (uid_t*) &translated);
if (r == -ENOENT)
goto not_found;
if (r < 0)
goto fail;
}
l = sizeof(char*) + strlen(name) + 1;
if (buflen < l) {
*errnop = ERANGE;
@ -420,7 +448,7 @@ direct_lookup:
gr->gr_name = buffer + sizeof(char*);
gr->gr_gid = (gid_t) translated;
gr->gr_passwd = (char*) "*"; /* locked */
gr->gr_passwd = (char*) DYNAMIC_USER_PASSWD;
gr->gr_mem = (char**) buffer;
*errnop = 0;
@ -478,11 +506,20 @@ enum nss_status _nss_systemd_getgrgid_r(
bypass = getenv_bool_secure("SYSTEMD_NSS_BYPASS_BUS");
if (bypass <= 0) {
r = sd_bus_open_system(&bus);
if (r < 0) {
if (r < 0)
bypass = 1;
goto direct_lookup;
}
}
if (bypass > 0) {
r = direct_lookup_uid(gid, &direct);
if (r == -ENOENT)
goto not_found;
if (r < 0)
goto fail;
translated = direct;
} else {
r = sd_bus_call_method(bus,
"org.freedesktop.systemd1",
"/org/freedesktop/systemd1",
@ -504,17 +541,6 @@ enum nss_status _nss_systemd_getgrgid_r(
goto fail;
}
direct_lookup:
if (bypass > 0) {
r = direct_lookup_uid(gid, &direct);
if (r == -ENOENT)
goto not_found;
if (r < 0)
goto fail;
translated = direct;
}
l = sizeof(char*) + strlen(translated) + 1;
if (buflen < l) {
*errnop = ERANGE;
@ -526,7 +552,7 @@ direct_lookup:
gr->gr_name = buffer + sizeof(char*);
gr->gr_gid = gid;
gr->gr_passwd = (char*) "*"; /* locked */
gr->gr_passwd = (char*) DYNAMIC_USER_PASSWD;
gr->gr_mem = (char**) buffer;
*errnop = 0;
@ -540,3 +566,299 @@ fail:
*errnop = -r;
return NSS_STATUS_UNAVAIL;
}
static void user_entry_free(UserEntry *p) {
if (!p)
return;
if (p->data)
LIST_REMOVE(entries, p->data->entries, p);
free(p->name);
free(p);
}
static int user_entry_add(GetentData *data, const char *name, uid_t id) {
UserEntry *p;
assert(data);
/* This happens when User= or Group= already exists statically. */
if (!uid_is_dynamic(id))
return -EINVAL;
p = new0(UserEntry, 1);
if (!p)
return -ENOMEM;
p->name = strdup(name);
if (!p->name) {
free(p);
return -ENOMEM;
}
p->id = id;
p->data = data;
LIST_PREPEND(entries, data->entries, p);
return 0;
}
static void systemd_endent(GetentData *data) {
UserEntry *p;
assert(data);
while ((p = data->entries))
user_entry_free(p);
data->position = NULL;
}
static enum nss_status nss_systemd_endent(GetentData *p) {
BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
assert_se(pthread_mutex_lock(&p->mutex) == 0);
systemd_endent(p);
assert_se(pthread_mutex_unlock(&p->mutex) == 0);
return NSS_STATUS_SUCCESS;
}
enum nss_status _nss_systemd_endpwent(void) {
return nss_systemd_endent(&getpwent_data);
}
enum nss_status _nss_systemd_endgrent(void) {
return nss_systemd_endent(&getgrent_data);
}
static int direct_enumeration(GetentData *p) {
_cleanup_closedir_ DIR *d = NULL;
struct dirent *de;
int r;
assert(p);
d = opendir("/run/systemd/dynamic-uid/");
if (!d)
return -errno;
FOREACH_DIRENT(de, d, return -errno) {
_cleanup_free_ char *name = NULL;
uid_t uid, verified;
if (!dirent_is_file(de))
continue;
r = parse_uid(de->d_name, &uid);
if (r < 0)
continue;
r = direct_lookup_uid(uid, &name);
if (r == -ENOMEM)
return r;
if (r < 0)
continue;
r = direct_lookup_name(name, &verified);
if (r < 0)
continue;
if (uid != verified)
continue;
r = user_entry_add(p, name, uid);
if (r == -ENOMEM)
return r;
if (r < 0)
continue;
}
return 0;
}
static enum nss_status systemd_setent(GetentData *p) {
_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
_cleanup_(sd_bus_message_unrefp) sd_bus_message* reply = NULL;
_cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
const char *name;
uid_t id;
int bypass, r;
BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
assert(p);
assert_se(pthread_mutex_lock(&p->mutex) == 0);
systemd_endent(p);
if (getenv_bool_secure("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0)
goto finish;
bypass = getenv_bool_secure("SYSTEMD_NSS_BYPASS_BUS");
if (bypass <= 0) {
r = sd_bus_open_system(&bus);
if (r < 0)
bypass = 1;
}
if (bypass > 0) {
r = direct_enumeration(p);
if (r < 0)
goto fail;
goto finish;
}
r = sd_bus_call_method(bus,
"org.freedesktop.systemd1",
"/org/freedesktop/systemd1",
"org.freedesktop.systemd1.Manager",
"GetDynamicUsers",
&error,
&reply,
NULL);
if (r < 0)
goto fail;
r = sd_bus_message_enter_container(reply, 'a', "(us)");
if (r < 0)
goto fail;
while ((r = sd_bus_message_read(reply, "(us)", &id, &name)) > 0) {
r = user_entry_add(p, name, id);
if (r == -ENOMEM)
goto fail;
if (r < 0)
continue;
}
if (r < 0)
goto fail;
r = sd_bus_message_exit_container(reply);
if (r < 0)
goto fail;
finish:
p->position = p->entries;
assert_se(pthread_mutex_unlock(&p->mutex) == 0);
return NSS_STATUS_SUCCESS;
fail:
systemd_endent(p);
assert_se(pthread_mutex_unlock(&p->mutex) == 0);
return NSS_STATUS_UNAVAIL;
}
enum nss_status _nss_systemd_setpwent(int stayopen) {
return systemd_setent(&getpwent_data);
}
enum nss_status _nss_systemd_setgrent(int stayopen) {
return systemd_setent(&getgrent_data);
}
enum nss_status _nss_systemd_getpwent_r(struct passwd *result, char *buffer, size_t buflen, int *errnop) {
enum nss_status ret;
UserEntry *p;
size_t len;
BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
assert(result);
assert(buffer);
assert(errnop);
assert_se(pthread_mutex_lock(&getpwent_data.mutex) == 0);
LIST_FOREACH(entries, p, getpwent_data.position) {
len = strlen(p->name) + 1;
if (buflen < len) {
*errnop = ERANGE;
ret = NSS_STATUS_TRYAGAIN;
goto finalize;
}
memcpy(buffer, p->name, len);
result->pw_name = buffer;
result->pw_uid = p->id;
result->pw_gid = p->id;
result->pw_gecos = (char*) DYNAMIC_USER_GECOS;
result->pw_passwd = (char*) DYNAMIC_USER_PASSWD;
result->pw_dir = (char*) DYNAMIC_USER_DIR;
result->pw_shell = (char*) DYNAMIC_USER_SHELL;
break;
}
if (!p) {
*errnop = ENOENT;
ret = NSS_STATUS_NOTFOUND;
goto finalize;
}
/* On success, step to the next entry. */
p = p->entries_next;
ret = NSS_STATUS_SUCCESS;
finalize:
/* Save position for the next call. */
getpwent_data.position = p;
assert_se(pthread_mutex_unlock(&getpwent_data.mutex) == 0);
return ret;
}
enum nss_status _nss_systemd_getgrent_r(struct group *result, char *buffer, size_t buflen, int *errnop) {
enum nss_status ret;
UserEntry *p;
size_t len;
BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
assert(result);
assert(buffer);
assert(errnop);
assert_se(pthread_mutex_lock(&getgrent_data.mutex) == 0);
LIST_FOREACH(entries, p, getgrent_data.position) {
len = sizeof(char*) + strlen(p->name) + 1;
if (buflen < len) {
*errnop = ERANGE;
ret = NSS_STATUS_TRYAGAIN;
goto finalize;
}
memzero(buffer, sizeof(char*));
strcpy(buffer + sizeof(char*), p->name);
result->gr_name = buffer + sizeof(char*);
result->gr_gid = p->id;
result->gr_passwd = (char*) DYNAMIC_USER_PASSWD;
result->gr_mem = (char**) buffer;
break;
}
if (!p) {
*errnop = ENOENT;
ret = NSS_STATUS_NOTFOUND;
goto finalize;
}
/* On success, step to the next entry. */
p = p->entries_next;
ret = NSS_STATUS_SUCCESS;
finalize:
/* Save position for the next call. */
getgrent_data.position = p;
assert_se(pthread_mutex_unlock(&getgrent_data.mutex) == 0);
return ret;
}

6
src/nss-systemd/nss-systemd.sym
View File

@ -13,7 +13,13 @@
global:
_nss_systemd_getpwnam_r;
_nss_systemd_getpwuid_r;
_nss_systemd_endpwent;
_nss_systemd_setpwent;
_nss_systemd_getpwent_r;
_nss_systemd_getgrnam_r;
_nss_systemd_getgrgid_r;
_nss_systemd_endgrent;
_nss_systemd_setgrent;
_nss_systemd_getgrent_r;
local: *;
};