diff options
Diffstat (limited to 'src/nss-systemd')
| l--------- | src/nss-systemd/GNUmakefile | 1 | ||||
| -rw-r--r-- | src/nss-systemd/Makefile | 45 | ||||
| -rw-r--r-- | src/nss-systemd/nss-systemd.c | 523 | ||||
| -rw-r--r-- | src/nss-systemd/nss-systemd.sym | 17 | ||||
| -rw-r--r-- | src/nss-systemd/nss-systemd.xml | 111 |
5 files changed, 697 insertions, 0 deletions
diff --git a/src/nss-systemd/GNUmakefile b/src/nss-systemd/GNUmakefile new file mode 120000 index 0000000000..54fdd42278 --- /dev/null +++ b/src/nss-systemd/GNUmakefile @@ -0,0 +1 @@ +../../GNUmakefile
\ No newline at end of file diff --git a/src/nss-systemd/Makefile b/src/nss-systemd/Makefile new file mode 100644 index 0000000000..90bd0ce886 --- /dev/null +++ b/src/nss-systemd/Makefile @@ -0,0 +1,45 @@ +# -*- Mode: makefile; indent-tabs-mode: t -*- +# +# This file is part of systemd. +# +# Copyright 2010-2012 Lennart Poettering +# Copyright 2010-2012 Kay Sievers +# Copyright 2013 Zbigniew Jędrzejewski-Szmek +# Copyright 2013 David Strauss +# Copyright 2016 Luke Shumaker +# +# systemd is free software; you can redistribute it and/or modify it +# under the terms of the GNU Lesser General Public License as published by +# the Free Software Foundation; either version 2.1 of the License, or +# (at your option) any later version. +# +# systemd is distributed in the hope that it will be useful, but +# WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +# Lesser General Public License for more details. +# +# You should have received a copy of the GNU Lesser General Public License +# along with systemd; If not, see <http://www.gnu.org/licenses/>. +include $(dir $(lastword $(MAKEFILE_LIST)))/../../config.mk +include $(topsrcdir)/build-aux/Makefile.head.mk + +libnss_systemd_la_SOURCES = \ + src/nss-systemd/nss-systemd.sym \ + src/nss-systemd/nss-systemd.c + +libnss_systemd_la_LDFLAGS = \ + -module \ + -export-dynamic \ + -avoid-version \ + -shared \ + -shrext .so.2 \ + -Wl,--version-script=$(srcdir)/nss-systemd.sym + +libnss_systemd_la_LIBADD = \ + libsystemd-internal.la \ + libsystemd-basic.la + +rootlib_LTLIBRARIES += \ + libnss_systemd.la + +include $(topsrcdir)/build-aux/Makefile.tail.mk diff --git a/src/nss-systemd/nss-systemd.c b/src/nss-systemd/nss-systemd.c new file mode 100644 index 0000000000..b23f805631 --- /dev/null +++ b/src/nss-systemd/nss-systemd.c @@ -0,0 +1,523 @@ +/*** + This file is part of systemd. + + Copyright 2016 Lennart Poettering + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + systemd is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with systemd; If not, see <http://www.gnu.org/licenses/>. +***/ + +#include <nss.h> + +#include <systemd/sd-bus.h> + +#include "sd-bus/bus-common-errors.h" +#include "systemd-basic/alloc-util.h" +#include "systemd-basic/env-util.h" +#include "systemd-basic/fs-util.h" +#include "systemd-basic/macro.h" +#include "systemd-basic/nss-util.h" +#include "systemd-basic/signal-util.h" +#include "systemd-basic/stdio-util.h" +#include "systemd-basic/string-util.h" +#include "systemd-basic/user-util.h" +#include "systemd-basic/util.h" + +#ifndef NOBODY_USER_NAME +#define NOBODY_USER_NAME "nobody" +#endif + +#ifndef NOBODY_GROUP_NAME +#define NOBODY_GROUP_NAME "nobody" +#endif + +static const struct passwd root_passwd = { + .pw_name = (char*) "root", + .pw_passwd = (char*) "x", /* see shadow file */ + .pw_uid = 0, + .pw_gid = 0, + .pw_gecos = (char*) "Super User", + .pw_dir = (char*) "/root", + .pw_shell = (char*) "/bin/sh", +}; + +static const struct passwd nobody_passwd = { + .pw_name = (char*) NOBODY_USER_NAME, + .pw_passwd = (char*) "*", /* locked */ + .pw_uid = 65534, + .pw_gid = 65534, + .pw_gecos = (char*) "User Nobody", + .pw_dir = (char*) "/", + .pw_shell = (char*) "/sbin/nologin", +}; + +static const struct group root_group = { + .gr_name = (char*) "root", + .gr_gid = 0, + .gr_passwd = (char*) "x", /* see shadow file */ + .gr_mem = (char*[]) { NULL }, +}; + +static const struct group nobody_group = { + .gr_name = (char*) NOBODY_GROUP_NAME, + .gr_gid = 65534, + .gr_passwd = (char*) "*", /* locked */ + .gr_mem = (char*[]) { NULL }, +}; + +NSS_GETPW_PROTOTYPES(systemd); +NSS_GETGR_PROTOTYPES(systemd); + +static int direct_lookup_name(const char *name, uid_t *ret) { + _cleanup_free_ char *s = NULL; + const char *path; + int r; + + assert(name); + + /* Normally, we go via the bus to resolve names. That has the benefit that it is available from any mount + * namespace and subject to proper authentication. However, there's one problem: if our module is called from + * dbus-daemon itself we really can't use D-Bus to communicate. In this case, resort to a client-side hack, + * and look for the dynamic names directly. This is pretty ugly, but breaks the cyclic dependency. */ + + path = strjoina("/run/systemd/dynamic-uid/direct:", name); + r = readlink_malloc(path, &s); + if (r < 0) + return r; + + return parse_uid(s, ret); +} + +static int direct_lookup_uid(uid_t uid, char **ret) { + char path[strlen("/run/systemd/dynamic-uid/direct:") + DECIMAL_STR_MAX(uid_t) + 1], *s; + int r; + + xsprintf(path, "/run/systemd/dynamic-uid/direct:" UID_FMT, uid); + + r = readlink_malloc(path, &s); + if (r < 0) + return r; + if (!valid_user_group_name(s)) { /* extra safety check */ + free(s); + return -EINVAL; + } + + *ret = s; + return 0; +} + +enum nss_status _nss_systemd_getpwnam_r( + const char *name, + struct passwd *pwd, + char *buffer, size_t buflen, + int *errnop) { + + uint32_t translated; + size_t l; + int r; + + BLOCK_SIGNALS(NSS_SIGNALS_BLOCK); + + assert(name); + assert(pwd); + + if (!valid_user_group_name(name)) { + r = -EINVAL; + goto fail; + } + + /* Synthesize entries for the root and nobody users, in case they are missing in /etc/passwd */ + if (streq(name, root_passwd.pw_name)) { + *pwd = root_passwd; + *errnop = 0; + return NSS_STATUS_SUCCESS; + } + if (streq(name, nobody_passwd.pw_name)) { + *pwd = nobody_passwd; + *errnop = 0; + return NSS_STATUS_SUCCESS; + } + + /* Make sure that we don't go in circles when allocating a dynamic UID by checking our own database */ + if (getenv_bool("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0) + goto not_found; + + if (getenv_bool("SYSTEMD_NSS_BYPASS_BUS") > 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; + + } else { + _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) + goto fail; + + r = sd_bus_call_method(bus, + "org.freedesktop.systemd1", + "/org/freedesktop/systemd1", + "org.freedesktop.systemd1.Manager", + "LookupDynamicUserByName", + &error, + &reply, + "s", + name); + if (r < 0) { + if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_DYNAMIC_USER)) + goto not_found; + + goto fail; + } + + r = sd_bus_message_read(reply, "u", &translated); + if (r < 0) + goto fail; + } + + l = strlen(name); + if (buflen < l+1) { + *errnop = ENOMEM; + return NSS_STATUS_TRYAGAIN; + } + + memcpy(buffer, name, l+1); + + 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"; + + *errnop = 0; + return NSS_STATUS_SUCCESS; + +not_found: + *errnop = 0; + return NSS_STATUS_NOTFOUND; + +fail: + *errnop = -r; + return NSS_STATUS_UNAVAIL; +} + +enum nss_status _nss_systemd_getpwuid_r( + uid_t uid, + struct passwd *pwd, + 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; + _cleanup_free_ char *direct = NULL; + const char *translated; + size_t l; + int r; + + BLOCK_SIGNALS(NSS_SIGNALS_BLOCK); + + if (!uid_is_valid(uid)) { + r = -EINVAL; + goto fail; + } + + /* Synthesize data for the root user and for nobody in case they are missing from /etc/passwd */ + if (uid == root_passwd.pw_uid) { + *pwd = root_passwd; + *errnop = 0; + return NSS_STATUS_SUCCESS; + } + if (uid == nobody_passwd.pw_uid) { + *pwd = nobody_passwd; + *errnop = 0; + return NSS_STATUS_SUCCESS; + } + + if (uid <= SYSTEM_UID_MAX) + goto not_found; + + if (getenv_bool("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0) + goto not_found; + + if (getenv_bool("SYSTEMD_NSS_BYPASS_BUS") > 0) { + + r = direct_lookup_uid(uid, &direct); + if (r == -ENOENT) + goto not_found; + if (r < 0) + goto fail; + + translated = direct; + + } else { + r = sd_bus_open_system(&bus); + if (r < 0) + goto fail; + + r = sd_bus_call_method(bus, + "org.freedesktop.systemd1", + "/org/freedesktop/systemd1", + "org.freedesktop.systemd1.Manager", + "LookupDynamicUserByUID", + &error, + &reply, + "u", + (uint32_t) uid); + if (r < 0) { + if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_DYNAMIC_USER)) + goto not_found; + + goto fail; + } + + r = sd_bus_message_read(reply, "s", &translated); + if (r < 0) + goto fail; + } + + l = strlen(translated) + 1; + if (buflen < l) { + *errnop = ENOMEM; + return NSS_STATUS_TRYAGAIN; + } + + memcpy(buffer, translated, l); + + 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"; + + *errnop = 0; + return NSS_STATUS_SUCCESS; + +not_found: + *errnop = 0; + return NSS_STATUS_NOTFOUND; + +fail: + *errnop = -r; + return NSS_STATUS_UNAVAIL; +} + +enum nss_status _nss_systemd_getgrnam_r( + const char *name, + struct group *gr, + char *buffer, size_t buflen, + int *errnop) { + + uint32_t translated; + size_t l; + int r; + + BLOCK_SIGNALS(NSS_SIGNALS_BLOCK); + + assert(name); + assert(gr); + + if (!valid_user_group_name(name)) { + r = -EINVAL; + goto fail; + } + + /* Synthesize records for root and nobody, in case they are missing form /etc/group */ + if (streq(name, root_group.gr_name)) { + *gr = root_group; + *errnop = 0; + return NSS_STATUS_SUCCESS; + } + if (streq(name, nobody_group.gr_name)) { + *gr = nobody_group; + *errnop = 0; + return NSS_STATUS_SUCCESS; + } + + if (getenv_bool("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0) + goto not_found; + + if (getenv_bool("SYSTEMD_NSS_BYPASS_BUS") > 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; + } else { + + _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) + goto fail; + + r = sd_bus_call_method(bus, + "org.freedesktop.systemd1", + "/org/freedesktop/systemd1", + "org.freedesktop.systemd1.Manager", + "LookupDynamicUserByName", + &error, + &reply, + "s", + name); + if (r < 0) { + if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_DYNAMIC_USER)) + goto not_found; + + goto fail; + } + + r = sd_bus_message_read(reply, "u", &translated); + if (r < 0) + goto fail; + } + + l = sizeof(char*) + strlen(name) + 1; + if (buflen < l) { + *errnop = ENOMEM; + return NSS_STATUS_TRYAGAIN; + } + + memzero(buffer, sizeof(char*)); + strcpy(buffer + sizeof(char*), name); + + gr->gr_name = buffer + sizeof(char*); + gr->gr_gid = (gid_t) translated; + gr->gr_passwd = (char*) "*"; /* locked */ + gr->gr_mem = (char**) buffer; + + *errnop = 0; + return NSS_STATUS_SUCCESS; + +not_found: + *errnop = 0; + return NSS_STATUS_NOTFOUND; + +fail: + *errnop = -r; + return NSS_STATUS_UNAVAIL; +} + +enum nss_status _nss_systemd_getgrgid_r( + gid_t gid, + struct group *gr, + 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; + _cleanup_free_ char *direct = NULL; + const char *translated; + size_t l; + int r; + + BLOCK_SIGNALS(NSS_SIGNALS_BLOCK); + + if (!gid_is_valid(gid)) { + r = -EINVAL; + goto fail; + } + + /* Synthesize records for root and nobody, in case they are missing from /etc/group */ + if (gid == root_group.gr_gid) { + *gr = root_group; + *errnop = 0; + return NSS_STATUS_SUCCESS; + } + if (gid == nobody_group.gr_gid) { + *gr = nobody_group; + *errnop = 0; + return NSS_STATUS_SUCCESS; + } + + if (gid <= SYSTEM_GID_MAX) + goto not_found; + + if (getenv_bool("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0) + goto not_found; + + if (getenv_bool("SYSTEMD_NSS_BYPASS_BUS") > 0) { + + r = direct_lookup_uid(gid, &direct); + if (r == -ENOENT) + goto not_found; + if (r < 0) + goto fail; + + translated = direct; + } else { + r = sd_bus_open_system(&bus); + if (r < 0) + goto fail; + + r = sd_bus_call_method(bus, + "org.freedesktop.systemd1", + "/org/freedesktop/systemd1", + "org.freedesktop.systemd1.Manager", + "LookupDynamicUserByUID", + &error, + &reply, + "u", + (uint32_t) gid); + if (r < 0) { + if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_DYNAMIC_USER)) + goto not_found; + + goto fail; + } + + r = sd_bus_message_read(reply, "s", &translated); + if (r < 0) + goto fail; + } + + l = sizeof(char*) + strlen(translated) + 1; + if (buflen < l) { + *errnop = ENOMEM; + return NSS_STATUS_TRYAGAIN; + } + + memzero(buffer, sizeof(char*)); + strcpy(buffer + sizeof(char*), translated); + + gr->gr_name = buffer + sizeof(char*); + gr->gr_gid = gid; + gr->gr_passwd = (char*) "*"; /* locked */ + gr->gr_mem = (char**) buffer; + + *errnop = 0; + return NSS_STATUS_SUCCESS; + +not_found: + *errnop = 0; + return NSS_STATUS_NOTFOUND; + +fail: + *errnop = -r; + return NSS_STATUS_UNAVAIL; +} diff --git a/src/nss-systemd/nss-systemd.sym b/src/nss-systemd/nss-systemd.sym new file mode 100644 index 0000000000..955078788a --- /dev/null +++ b/src/nss-systemd/nss-systemd.sym @@ -0,0 +1,17 @@ +/*** + This file is part of systemd. + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. +***/ + +{ +global: + _nss_systemd_getpwnam_r; + _nss_systemd_getpwuid_r; + _nss_systemd_getgrnam_r; + _nss_systemd_getgrgid_r; +local: *; +}; diff --git a/src/nss-systemd/nss-systemd.xml b/src/nss-systemd/nss-systemd.xml new file mode 100644 index 0000000000..71aed4df83 --- /dev/null +++ b/src/nss-systemd/nss-systemd.xml @@ -0,0 +1,111 @@ +<?xml version='1.0'?> <!--*-nxml-*--> +<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" + "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> + +<!-- + This file is part of systemd. + + Copyright 2016 Lennart Poettering + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + systemd is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with systemd; If not, see <http://www.gnu.org/licenses/>. +--> + +<refentry id="nss-systemd"> + + <refentryinfo> + <title>nss-systemd</title> + <productname>systemd</productname> + + <authorgroup> + <author> + <contrib>Developer</contrib> + <firstname>Lennart</firstname> + <surname>Poettering</surname> + <email>lennart@poettering.net</email> + </author> + </authorgroup> + </refentryinfo> + + <refmeta> + <refentrytitle>nss-systemd</refentrytitle> + <manvolnum>8</manvolnum> + </refmeta> + + <refnamediv> + <refname>nss-systemd</refname> + <refname>libnss_systemd.so.2</refname> + <refpurpose>Provide UNIX user and group name resolution for dynamic users and groups.</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <para><filename>libnss_systemd.so.2</filename></para> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para><command>nss-systemd</command> is a plug-in module for the GNU Name Service Switch (NSS) functionality of the + GNU C Library (<command>glibc</command>), providing UNIX user and group name resolution for dynamic users and + groups allocated through the <varname>DynamicUser=</varname> option in systemd unit files. See + <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details on + this option.</para> + + <para>This module also ensures that the root and nobody users and groups (i.e. the users/groups with the UIDs/GIDs + 0 and 65534) remain resolvable at all times, even if they aren't listed in <filename>/etc/passwd</filename> or + <filename>/etc/group</filename>, or if these files are missing.</para> + + <para>To activate the NSS module, add <literal>systemd</literal> to the lines starting with + <literal>passwd:</literal> and <literal>group:</literal> in <filename>/etc/nsswitch.conf</filename>.</para> + + <para>It is recommended to place <literal>systemd</literal> after the <literal>files</literal> or + <literal>compat</literal> entry of the <filename>/etc/nsswitch.conf</filename> lines so that + <filename>/etc/passwd</filename> and <filename>/etc/group</filename> based mappings take precedence.</para> + </refsect1> + + <refsect1> + <title>Example</title> + + <para>Here is an example <filename>/etc/nsswitch.conf</filename> file that enables + <command>nss-systemd</command> correctly:</para> + + <programlisting>passwd: compat mymachines <command>systemd</command> +group: compat mymachines <command>systemd</command> +shadow: compat + +hosts: files mymachines resolve [!UNAVAIL=return] dns myhostname +networks: files + +protocols: db files +services: db files +ethers: db files +rpc: db files + +netgroup: nis</programlisting> + + </refsect1> + + <refsect1> + <title>See Also</title> + <para> + <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry><refentrytitle>nss-resolve</refentrytitle><manvolnum>8</manvolnum></citerefentry>, + <citerefentry><refentrytitle>nss-myhostname</refentrytitle><manvolnum>8</manvolnum></citerefentry>, + <citerefentry><refentrytitle>nss-mymachines</refentrytitle><manvolnum>8</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>nsswitch.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>getent</refentrytitle><manvolnum>1</manvolnum></citerefentry> + </para> + </refsect1> + +</refentry> |