diff options
Diffstat (limited to 'src/login/pam_systemd.c')
| -rw-r--r-- | src/login/pam_systemd.c | 548 |
1 files changed, 548 insertions, 0 deletions
diff --git a/src/login/pam_systemd.c b/src/login/pam_systemd.c new file mode 100644 index 0000000000..262621d43f --- /dev/null +++ b/src/login/pam_systemd.c @@ -0,0 +1,548 @@ +/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ + +/*** + This file is part of systemd. + + Copyright 2010 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 <errno.h> +#include <fcntl.h> +#include <sys/file.h> +#include <pwd.h> +#include <endian.h> +#include <sys/capability.h> + +#include <security/pam_modules.h> +#include <security/_pam_macros.h> +#include <security/pam_modutil.h> +#include <security/pam_ext.h> +#include <security/pam_misc.h> + +#include "util.h" +#include "audit.h" +#include "macro.h" +#include "strv.h" +#include "bus-util.h" +#include "def.h" +#include "socket-util.h" +#include "fileio.h" +#include "bus-error.h" + +static int parse_argv( + pam_handle_t *handle, + int argc, const char **argv, + const char **class, + const char **type, + bool *debug) { + + unsigned i; + + assert(argc >= 0); + assert(argc == 0 || argv); + + for (i = 0; i < (unsigned) argc; i++) { + if (startswith(argv[i], "class=")) { + if (class) + *class = argv[i] + 6; + + } else if (startswith(argv[i], "type=")) { + if (type) + *type = argv[i] + 5; + + } else if (streq(argv[i], "debug")) { + if (debug) + *debug = true; + + } else if (startswith(argv[i], "debug=")) { + int k; + + k = parse_boolean(argv[i] + 6); + if (k < 0) + pam_syslog(handle, LOG_WARNING, "Failed to parse debug= argument, ignoring."); + else if (debug) + *debug = k; + + } else + pam_syslog(handle, LOG_WARNING, "Unknown parameter '%s', ignoring", argv[i]); + } + + return 0; +} + +static int get_user_data( + pam_handle_t *handle, + const char **ret_username, + struct passwd **ret_pw) { + + const char *username = NULL; + struct passwd *pw = NULL; + int r; + + assert(handle); + assert(ret_username); + assert(ret_pw); + + r = pam_get_user(handle, &username, NULL); + if (r != PAM_SUCCESS) { + pam_syslog(handle, LOG_ERR, "Failed to get user name."); + return r; + } + + if (isempty(username)) { + pam_syslog(handle, LOG_ERR, "User name not valid."); + return PAM_AUTH_ERR; + } + + pw = pam_modutil_getpwnam(handle, username); + if (!pw) { + pam_syslog(handle, LOG_ERR, "Failed to get user data."); + return PAM_USER_UNKNOWN; + } + + *ret_pw = pw; + *ret_username = username ? username : pw->pw_name; + + return PAM_SUCCESS; +} + +static int get_seat_from_display(const char *display, const char **seat, uint32_t *vtnr) { + union sockaddr_union sa = { + .un.sun_family = AF_UNIX, + }; + _cleanup_free_ char *p = NULL, *tty = NULL; + _cleanup_close_ int fd = -1; + struct ucred ucred; + int v, r; + + assert(display); + assert(vtnr); + + /* We deduce the X11 socket from the display name, then use + * SO_PEERCRED to determine the X11 server process, ask for + * the controlling tty of that and if it's a VC then we know + * the seat and the virtual terminal. Sounds ugly, is only + * semi-ugly. */ + + r = socket_from_display(display, &p); + if (r < 0) + return r; + strncpy(sa.un.sun_path, p, sizeof(sa.un.sun_path)-1); + + fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0); + if (fd < 0) + return -errno; + + if (connect(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path)) < 0) + return -errno; + + r = getpeercred(fd, &ucred); + if (r < 0) + return r; + + r = get_ctty(ucred.pid, NULL, &tty); + if (r < 0) + return r; + + v = vtnr_from_tty(tty); + if (v < 0) + return v; + else if (v == 0) + return -ENOENT; + + if (seat) + *seat = "seat0"; + *vtnr = (uint32_t) v; + + return 0; +} + +static int export_legacy_dbus_address( + pam_handle_t *handle, + uid_t uid, + const char *runtime) { + +#ifdef ENABLE_KDBUS + _cleanup_free_ char *s = NULL; + int r; + + /* skip export if kdbus is not active */ + if (access("/dev/kdbus", F_OK) < 0) + return PAM_SUCCESS; + + if (asprintf(&s, KERNEL_USER_BUS_FMT ";" UNIX_USER_BUS_FMT, + uid, runtime) < 0) { + pam_syslog(handle, LOG_ERR, "Failed to set bus variable."); + return PAM_BUF_ERR; + } + + r = pam_misc_setenv(handle, "DBUS_SESSION_BUS_ADDRESS", s, 0); + if (r != PAM_SUCCESS) { + pam_syslog(handle, LOG_ERR, "Failed to set bus variable."); + return r; + } +#endif + return PAM_SUCCESS; +} + +_public_ PAM_EXTERN int pam_sm_open_session( + pam_handle_t *handle, + int flags, + int argc, const char **argv) { + + _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL; + _cleanup_bus_message_unref_ sd_bus_message *reply = NULL; + const char + *username, *id, *object_path, *runtime_path, + *service = NULL, + *tty = NULL, *display = NULL, + *remote_user = NULL, *remote_host = NULL, + *seat = NULL, + *type = NULL, *class = NULL, + *class_pam = NULL, *type_pam = NULL, *cvtnr = NULL, *desktop = NULL; + _cleanup_bus_unref_ sd_bus *bus = NULL; + int session_fd = -1, existing, r; + bool debug = false, remote; + struct passwd *pw; + uint32_t vtnr = 0; + uid_t original_uid; + + assert(handle); + + /* Make this a NOP on non-logind systems */ + if (!logind_running()) + return PAM_SUCCESS; + + if (parse_argv(handle, + argc, argv, + &class_pam, + &type_pam, + &debug) < 0) + return PAM_SESSION_ERR; + + if (debug) + pam_syslog(handle, LOG_DEBUG, "pam-systemd initializing"); + + r = get_user_data(handle, &username, &pw); + if (r != PAM_SUCCESS) { + pam_syslog(handle, LOG_ERR, "Failed to get user data."); + return r; + } + + /* Make sure we don't enter a loop by talking to + * systemd-logind when it is actually waiting for the + * background to finish start-up. If the service is + * "systemd-user" we simply set XDG_RUNTIME_DIR and + * leave. */ + + pam_get_item(handle, PAM_SERVICE, (const void**) &service); + if (streq_ptr(service, "systemd-user")) { + _cleanup_free_ char *p = NULL, *rt = NULL; + + if (asprintf(&p, "/run/systemd/users/"UID_FMT, pw->pw_uid) < 0) + return PAM_BUF_ERR; + + r = parse_env_file(p, NEWLINE, + "RUNTIME", &rt, + NULL); + if (r < 0 && r != -ENOENT) + return PAM_SESSION_ERR; + + if (rt) { + r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", rt, 0); + if (r != PAM_SUCCESS) { + pam_syslog(handle, LOG_ERR, "Failed to set runtime dir."); + return r; + } + + r = export_legacy_dbus_address(handle, pw->pw_uid, rt); + if (r != PAM_SUCCESS) + return r; + } + + return PAM_SUCCESS; + } + + /* Otherwise, we ask logind to create a session for us */ + + pam_get_item(handle, PAM_XDISPLAY, (const void**) &display); + pam_get_item(handle, PAM_TTY, (const void**) &tty); + pam_get_item(handle, PAM_RUSER, (const void**) &remote_user); + pam_get_item(handle, PAM_RHOST, (const void**) &remote_host); + + seat = pam_getenv(handle, "XDG_SEAT"); + if (isempty(seat)) + seat = getenv("XDG_SEAT"); + + cvtnr = pam_getenv(handle, "XDG_VTNR"); + if (isempty(cvtnr)) + cvtnr = getenv("XDG_VTNR"); + + type = pam_getenv(handle, "XDG_SESSION_TYPE"); + if (isempty(type)) + type = getenv("XDG_SESSION_TYPE"); + if (isempty(type)) + type = type_pam; + + class = pam_getenv(handle, "XDG_SESSION_CLASS"); + if (isempty(class)) + class = getenv("XDG_SESSION_CLASS"); + if (isempty(class)) + class = class_pam; + + desktop = pam_getenv(handle, "XDG_SESSION_DESKTOP"); + if (isempty(desktop)) + desktop = getenv("XDG_SESSION_DESKTOP"); + + tty = strempty(tty); + + if (strchr(tty, ':')) { + /* A tty with a colon is usually an X11 display, + * placed there to show up in utmp. We rearrange + * things and don't pretend that an X display was a + * tty. */ + + if (isempty(display)) + display = tty; + tty = NULL; + } else if (streq(tty, "cron")) { + /* cron has been setting PAM_TTY to "cron" for a very + * long time and it probably shouldn't stop doing that + * for compatibility reasons. */ + type = "unspecified"; + class = "background"; + tty = NULL; + } else if (streq(tty, "ssh")) { + /* ssh has been setting PAM_TTY to "ssh" for a very + * long time and probably shouldn't stop doing that + * for compatibility reasons. */ + type ="tty"; + class = "user"; + tty = NULL; + } + + /* If this fails vtnr will be 0, that's intended */ + if (!isempty(cvtnr)) + safe_atou32(cvtnr, &vtnr); + + if (!isempty(display) && !vtnr) { + if (isempty(seat)) + get_seat_from_display(display, &seat, &vtnr); + else if (streq(seat, "seat0")) + get_seat_from_display(display, NULL, &vtnr); + } + + if (seat && !streq(seat, "seat0") && vtnr != 0) { + pam_syslog(handle, LOG_DEBUG, "Ignoring vtnr %d for %s which is not seat0", vtnr, seat); + vtnr = 0; + } + + if (isempty(type)) + type = !isempty(display) ? "x11" : + !isempty(tty) ? "tty" : "unspecified"; + + if (isempty(class)) + class = streq(type, "unspecified") ? "background" : "user"; + + remote = !isempty(remote_host) && + !streq_ptr(remote_host, "localhost") && + !streq_ptr(remote_host, "localhost.localdomain"); + + /* Talk to logind over the message bus */ + + r = sd_bus_open_system(&bus); + if (r < 0) { + pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror(-r)); + return PAM_SESSION_ERR; + } + + if (debug) + pam_syslog(handle, LOG_DEBUG, "Asking logind to create session: " + "uid=%u pid=%u service=%s type=%s class=%s desktop=%s seat=%s vtnr=%u tty=%s display=%s remote=%s remote_user=%s remote_host=%s", + pw->pw_uid, getpid(), + strempty(service), + type, class, strempty(desktop), + strempty(seat), vtnr, strempty(tty), strempty(display), + yes_no(remote), strempty(remote_user), strempty(remote_host)); + + r = sd_bus_call_method(bus, + "org.freedesktop.login1", + "/org/freedesktop/login1", + "org.freedesktop.login1.Manager", + "CreateSession", + &error, + &reply, + "uusssssussbssa(sv)", + (uint32_t) pw->pw_uid, + (uint32_t) getpid(), + service, + type, + class, + desktop, + seat, + vtnr, + tty, + display, + remote, + remote_user, + remote_host, + 0); + if (r < 0) { + pam_syslog(handle, LOG_ERR, "Failed to create session: %s", bus_error_message(&error, r)); + return PAM_SYSTEM_ERR; + } + + r = sd_bus_message_read(reply, + "soshusub", + &id, + &object_path, + &runtime_path, + &session_fd, + &original_uid, + &seat, + &vtnr, + &existing); + if (r < 0) { + pam_syslog(handle, LOG_ERR, "Failed to parse message: %s", strerror(-r)); + return PAM_SESSION_ERR; + } + + if (debug) + pam_syslog(handle, LOG_DEBUG, "Reply from logind: " + "id=%s object_path=%s runtime_path=%s session_fd=%d seat=%s vtnr=%u original_uid=%u", + id, object_path, runtime_path, session_fd, seat, vtnr, original_uid); + + r = pam_misc_setenv(handle, "XDG_SESSION_ID", id, 0); + if (r != PAM_SUCCESS) { + pam_syslog(handle, LOG_ERR, "Failed to set session id."); + return r; + } + + if (original_uid == pw->pw_uid) { + /* Don't set $XDG_RUNTIME_DIR if the user we now + * authenticated for does not match the original user + * of the session. We do this in order not to result + * in privileged apps clobbering the runtime directory + * unnecessarily. */ + + r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", runtime_path, 0); + if (r != PAM_SUCCESS) { + pam_syslog(handle, LOG_ERR, "Failed to set runtime dir."); + return r; + } + + r = export_legacy_dbus_address(handle, pw->pw_uid, runtime_path); + if (r != PAM_SUCCESS) + return r; + } + + if (!isempty(seat)) { + r = pam_misc_setenv(handle, "XDG_SEAT", seat, 0); + if (r != PAM_SUCCESS) { + pam_syslog(handle, LOG_ERR, "Failed to set seat."); + return r; + } + } + + if (vtnr > 0) { + char buf[DECIMAL_STR_MAX(vtnr)]; + sprintf(buf, "%u", vtnr); + + r = pam_misc_setenv(handle, "XDG_VTNR", buf, 0); + if (r != PAM_SUCCESS) { + pam_syslog(handle, LOG_ERR, "Failed to set virtual terminal number."); + return r; + } + } + + r = pam_set_data(handle, "systemd.existing", INT_TO_PTR(!!existing), NULL); + if (r != PAM_SUCCESS) { + pam_syslog(handle, LOG_ERR, "Failed to install existing flag."); + return r; + } + + if (session_fd >= 0) { + session_fd = fcntl(session_fd, F_DUPFD_CLOEXEC, 3); + if (session_fd < 0) { + pam_syslog(handle, LOG_ERR, "Failed to dup session fd: %m"); + return PAM_SESSION_ERR; + } + + r = pam_set_data(handle, "systemd.session-fd", INT_TO_PTR(session_fd+1), NULL); + if (r != PAM_SUCCESS) { + pam_syslog(handle, LOG_ERR, "Failed to install session fd."); + safe_close(session_fd); + return r; + } + } + + return PAM_SUCCESS; +} + +_public_ PAM_EXTERN int pam_sm_close_session( + pam_handle_t *handle, + int flags, + int argc, const char **argv) { + + _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL; + _cleanup_bus_unref_ sd_bus *bus = NULL; + const void *existing = NULL; + const char *id; + int r; + + assert(handle); + + /* Only release session if it wasn't pre-existing when we + * tried to create it */ + pam_get_data(handle, "systemd.existing", &existing); + + id = pam_getenv(handle, "XDG_SESSION_ID"); + if (id && !existing) { + + /* Before we go and close the FIFO we need to tell + * logind that this is a clean session shutdown, so + * that it doesn't just go and slaughter us + * immediately after closing the fd */ + + r = sd_bus_open_system(&bus); + if (r < 0) { + pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror(-r)); + return PAM_SESSION_ERR; + } + + r = sd_bus_call_method(bus, + "org.freedesktop.login1", + "/org/freedesktop/login1", + "org.freedesktop.login1.Manager", + "ReleaseSession", + &error, + NULL, + "s", + id); + if (r < 0) { + pam_syslog(handle, LOG_ERR, "Failed to release session: %s", bus_error_message(&error, r)); + return PAM_SESSION_ERR; + } + } + + /* Note that we are knowingly leaking the FIFO fd here. This + * way, logind can watch us die. If we closed it here it would + * not have any clue when that is completed. Given that one + * cannot really have multiple PAM sessions open from the same + * process this means we will leak one FD at max. */ + + return PAM_SUCCESS; +} |