| /*** |
| 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 "sd-bus.h" |
| |
| #include "alloc-util.h" |
| #include "bus-common-errors.h" |
| #include "env-util.h" |
| #include "fs-util.h" |
| #include "macro.h" |
| #include "nss-util.h" |
| #include "signal-util.h" |
| #include "stdio-util.h" |
| #include "string-util.h" |
| #include "user-util.h" |
| #include "util.h" |
| |
| 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 bypass, r; |
| |
| BLOCK_SIGNALS(NSS_SIGNALS_BLOCK); |
| |
| assert(name); |
| assert(pwd); |
| |
| /* If the username is not valid, then we don't know it. Ideally libc would filter these for us anyway. We don't |
| * generate EINVAL here, because it isn't really out business to complain about invalid user names. */ |
| if (!valid_user_group_name(name)) |
| goto not_found; |
| |
| /* Synthesize entries for the root and nobody users, in case they are missing in /etc/passwd */ |
| if (getenv_bool_secure("SYSTEMD_NSS_BYPASS_SYNTHETIC") <= 0) { |
| 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_secure("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0) |
| goto not_found; |
| |
| 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) { |
| bypass = 1; |
| goto direct_lookup; |
| } |
| |
| 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; |
| } |
| |
| 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; |
| 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 bypass, r; |
| |
| BLOCK_SIGNALS(NSS_SIGNALS_BLOCK); |
| |
| if (!uid_is_valid(uid)) |
| goto not_found; |
| |
| /* Synthesize data for the root user and for nobody in case they are missing from /etc/passwd */ |
| if (getenv_bool_secure("SYSTEMD_NSS_BYPASS_SYNTHETIC") <= 0) { |
| 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_secure("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0) |
| goto not_found; |
| |
| bypass = getenv_bool_secure("SYSTEMD_NSS_BYPASS_BUS"); |
| if (bypass <= 0) { |
| r = sd_bus_open_system(&bus); |
| if (r < 0) { |
| bypass = 1; |
| goto direct_lookup; |
| } |
| |
| 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; |
| } |
| |
| 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; |
| 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 bypass, r; |
| |
| BLOCK_SIGNALS(NSS_SIGNALS_BLOCK); |
| |
| assert(name); |
| assert(gr); |
| |
| if (!valid_user_group_name(name)) |
| goto not_found; |
| |
| /* Synthesize records for root and nobody, in case they are missing form /etc/group */ |
| if (getenv_bool_secure("SYSTEMD_NSS_BYPASS_SYNTHETIC") <= 0) { |
| 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_secure("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0) |
| goto not_found; |
| |
| 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) { |
| bypass = 1; |
| goto direct_lookup; |
| } |
| |
| 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; |
| } |
| |
| 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; |
| 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 bypass, r; |
| |
| BLOCK_SIGNALS(NSS_SIGNALS_BLOCK); |
| |
| if (!gid_is_valid(gid)) |
| goto not_found; |
| |
| /* Synthesize records for root and nobody, in case they are missing from /etc/group */ |
| if (getenv_bool_secure("SYSTEMD_NSS_BYPASS_SYNTHETIC") <= 0) { |
| 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_secure("SYSTEMD_NSS_DYNAMIC_BYPASS") > 0) |
| goto not_found; |
| |
| bypass = getenv_bool_secure("SYSTEMD_NSS_BYPASS_BUS"); |
| if (bypass <= 0) { |
| r = sd_bus_open_system(&bus); |
| if (r < 0) { |
| bypass = 1; |
| goto direct_lookup; |
| } |
| |
| 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; |
| } |
| |
| 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; |
| 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; |
| } |