diff --git a/Makefile-man.am b/Makefile-man.am index 8ab733360d..3ac1906a4a 100644 --- a/Makefile-man.am +++ b/Makefile-man.am @@ -23,6 +23,7 @@ MANPAGES += \ man/localtime.5 \ man/machine-id.5 \ man/machine-info.5 \ + man/nss-systemd.8 \ man/os-release.5 \ man/sd-bus-errors.3 \ man/sd-bus.3 \ @@ -255,6 +256,7 @@ MANPAGES_ALIAS += \ man/SD_WARNING.3 \ man/init.1 \ man/journald.conf.d.5 \ + man/libnss_systemd.so.2.8 \ man/poweroff.8 \ man/reboot.8 \ man/sd_bus_creds_get_audit_login_uid.3 \ @@ -587,6 +589,7 @@ man/SD_NOTICE.3: man/sd-daemon.3 man/SD_WARNING.3: man/sd-daemon.3 man/init.1: man/systemd.1 man/journald.conf.d.5: man/journald.conf.5 +man/libnss_systemd.so.2.8: man/nss-systemd.8 man/poweroff.8: man/halt.8 man/reboot.8: man/halt.8 man/sd_bus_creds_get_audit_login_uid.3: man/sd_bus_creds_get_pid.3 @@ -1071,6 +1074,9 @@ man/init.html: man/systemd.html man/journald.conf.d.html: man/journald.conf.html $(html-alias) +man/libnss_systemd.so.2.html: man/nss-systemd.html + $(html-alias) + man/poweroff.html: man/halt.html $(html-alias) @@ -2519,6 +2525,7 @@ EXTRA_DIST += \ man/nss-myhostname.xml \ man/nss-mymachines.xml \ man/nss-resolve.xml \ + man/nss-systemd.xml \ man/os-release.xml \ man/pam_systemd.xml \ man/resolved.conf.xml \ diff --git a/Makefile.am b/Makefile.am index 3d5ce1e2c3..a4241122d5 100644 --- a/Makefile.am +++ b/Makefile.am @@ -5001,6 +5001,27 @@ test_nss_LDADD = \ manual_tests += \ test-nss +# ------------------------------------------------------------------------------ +libnss_systemd_la_SOURCES = \ + src/nss-systemd/nss-systemd.sym \ + src/nss-systemd/nss-systemd.c + +libnss_systemd_la_LDFLAGS = \ + $(AM_LDFLAGS) \ + -module \ + -export-dynamic \ + -avoid-version \ + -shared \ + -shrext .so.2 \ + -Wl,--version-script=$(top_srcdir)/src/nss-systemd/nss-systemd.sym + +libnss_systemd_la_LIBADD = \ + libsystemd-internal.la \ + libbasic.la + +lib_LTLIBRARIES += \ + libnss_systemd.la + # ------------------------------------------------------------------------------ if HAVE_MYHOSTNAME libnss_myhostname_la_SOURCES = \ diff --git a/README b/README index ca8993cb12..19c15a70b0 100644 --- a/README +++ b/README @@ -201,7 +201,7 @@ USERS AND GROUPS: "systemd-coredump" system user and group to exist. NSS: - systemd ships with three NSS modules: + systemd ships with four glibc NSS modules: nss-myhostname resolves the local hostname to locally configured IP addresses, as well as "localhost" to @@ -210,15 +210,22 @@ NSS: nss-resolve enables DNS resolution via the systemd-resolved DNS/LLMNR caching stub resolver "systemd-resolved". - nss-mymachines enables resolution of all local containers - registered with machined to their respective IP addresses. + nss-mymachines enables resolution of all local containers registered + with machined to their respective IP addresses. It also maps UID/GIDs + ranges used by containers to useful names. - To make use of these NSS modules, please add them to the - "hosts: " line in /etc/nsswitch.conf. The "resolve" module - should replace the glibc "dns" module in this file. + nss-systemd enables resolution of all dynamically allocated service + users. (See the DynamicUser= setting in unit files.) - The three modules should be used in the following order: + To make use of these NSS modules, please add them to the "hosts:", + "passwd:" and "group:" lines in /etc/nsswitch.conf. The "resolve" + module should replace the glibc "dns" module in this file (and don't + worry, it chain-loads the "dns" module if it can't talk to resolved). + The four modules should be used in the following order: + + passwd: compat mymachines systemd + group: compat mymachines systemd hosts: files mymachines resolve myhostname SYSV INIT.D SCRIPTS: diff --git a/man/nss-myhostname.xml b/man/nss-myhostname.xml index a920ec334f..b1daaba02b 100644 --- a/man/nss-myhostname.xml +++ b/man/nss-myhostname.xml @@ -106,8 +106,8 @@ Here is an example /etc/nsswitch.conf file that enables nss-myhostname correctly: -passwd: compat mymachines -group: compat mymachines +passwd: compat mymachines systemd +group: compat mymachines systemd shadow: compat hosts: files mymachines resolve myhostname @@ -138,6 +138,7 @@ netgroup: nis See Also systemd1, + nss-systemd8, nss-resolve8, nss-mymachines8, nsswitch.conf5, diff --git a/man/nss-mymachines.xml b/man/nss-mymachines.xml index ec047449bf..a70119e256 100644 --- a/man/nss-mymachines.xml +++ b/man/nss-mymachines.xml @@ -82,8 +82,8 @@ Here is an example /etc/nsswitch.conf file that enables nss-mymachines correctly: - passwd: compat mymachines -group: compat mymachines + passwd: compat mymachines systemd +group: compat mymachines systemd shadow: compat hosts: files mymachines resolve myhostname @@ -103,6 +103,7 @@ netgroup: nis systemd1, systemd-machined.service8, + nss-systemd8, nss-resolve8, nss-myhostname8, nsswitch.conf5, diff --git a/man/nss-resolve.xml b/man/nss-resolve.xml index d9e56453e8..e6cc1d982a 100644 --- a/man/nss-resolve.xml +++ b/man/nss-resolve.xml @@ -81,8 +81,8 @@ Here is an example /etc/nsswitch.conf file that enables nss-resolve correctly: -passwd: compat mymachines -group: compat mymachines +passwd: compat mymachines systemd +group: compat mymachines systemd shadow: compat hosts: files mymachines resolve myhostname @@ -102,8 +102,9 @@ netgroup: nis systemd1, systemd-resolved8, - nss-mymachines8, + nss-systemd8, nss-myhostname8, + nss-mymachines8, nsswitch.conf5 diff --git a/man/nss-systemd.xml b/man/nss-systemd.xml new file mode 100644 index 0000000000..4228372e51 --- /dev/null +++ b/man/nss-systemd.xml @@ -0,0 +1,107 @@ + + + + + + + + + nss-systemd + systemd + + + + Developer + Lennart + Poettering + lennart@poettering.net + + + + + + nss-systemd + 8 + + + + nss-systemd + libnss_systemd.so.2 + Provide UNIX user and group name resolution for dynamic users and groups. + + + + libnss_systemd.so.2 + + + + Description + + nss-systemd is a plug-in module for the GNU Name Service Switch (NSS) functionality of the + GNU C Library (glibc), providing UNIX user and group name resolution for dynamic users and + groups allocated through the DynamicUser= option in systemd unit files. See + systemd.exec5 for details on + this option. + + To activate the NSS module, add systemd to the lines starting with + passwd: and group: in /etc/nsswitch.conf. + + It is recommended to place systemd after the files or + compat entry of the /etc/nsswitch.conf lines so that + /etc/passwd and /etc/group based mappings take precedence. + + + + Example + + Here is an example /etc/nsswitch.conf file that enables + nss-systemd correctly: + + passwd: compat mymachines systemd +group: compat mymachines systemd +shadow: compat + +hosts: files mymachines resolve myhostname +networks: files + +protocols: db files +services: db files +ethers: db files +rpc: db files + +netgroup: nis + + + + + See Also + + systemd1, + systemd.exec5, + nss-resolve8, + nss-myhostname8, + nss-mymachines8, + nsswitch.conf5, + getent1 + + + + diff --git a/src/core/execute.c b/src/core/execute.c index c186f2a705..26e9cd5339 100644 --- a/src/core/execute.c +++ b/src/core/execute.c @@ -1670,6 +1670,12 @@ static int exec_child( if (context->dynamic_user && dcreds) { + /* Make sure we bypass our own NSS module for any NSS checks */ + if (putenv((char*) "SYSTEMD_NSS_DYNAMIC_BYPASS=1") != 0) { + *exit_status = EXIT_USER; + return -errno; + } + r = dynamic_creds_realize(dcreds, &uid, &gid); if (r < 0) { *exit_status = EXIT_USER; diff --git a/src/nss-systemd/Makefile b/src/nss-systemd/Makefile new file mode 120000 index 0000000000..d0b0e8e008 --- /dev/null +++ b/src/nss-systemd/Makefile @@ -0,0 +1 @@ +../Makefile \ No newline at end of file diff --git a/src/nss-systemd/nss-systemd.c b/src/nss-systemd/nss-systemd.c new file mode 100644 index 0000000000..e7a4393bb0 --- /dev/null +++ b/src/nss-systemd/nss-systemd.c @@ -0,0 +1,332 @@ +/*** + 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 . +***/ + +#include + +#include "sd-bus.h" + +#include "bus-common-errors.h" +#include "env-util.h" +#include "macro.h" +#include "nss-util.h" +#include "signal-util.h" +#include "user-util.h" +#include "util.h" + +NSS_GETPW_PROTOTYPES(systemd); +NSS_GETGR_PROTOTYPES(systemd); + +enum nss_status _nss_systemd_getpwnam_r( + const char *name, + 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; + uint32_t translated; + size_t l; + int r; + + BLOCK_SIGNALS(NSS_SIGNALS_BLOCK); + + assert(name); + assert(pwd); + + /* 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; + + 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; + const char *translated; + size_t l; + int r; + + BLOCK_SIGNALS(NSS_SIGNALS_BLOCK); + + if (!uid_is_valid(uid)) { + r = -EINVAL; + goto fail; + } + + if (uid <= SYSTEM_UID_MAX) + goto not_found; + + if (getenv_bool("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0) + goto not_found; + + 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) { + + _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 r; + + BLOCK_SIGNALS(NSS_SIGNALS_BLOCK); + + assert(name); + assert(gr); + + if (getenv_bool("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0) + goto not_found; + + 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; + const char *translated; + size_t l; + int r; + + BLOCK_SIGNALS(NSS_SIGNALS_BLOCK); + + if (!gid_is_valid(gid)) { + r = -EINVAL; + goto fail; + } + + if (gid <= SYSTEM_GID_MAX) + goto not_found; + + if (getenv_bool("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0) + goto not_found; + + 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: *; +};