689 lines
25 KiB
C
689 lines
25 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#include <endian.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <pwd.h>
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#include <security/_pam_macros.h>
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#include <security/pam_ext.h>
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#include <security/pam_misc.h>
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#include <security/pam_modules.h>
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#include <security/pam_modutil.h>
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#include <sys/file.h>
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#include "alloc-util.h"
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#include "audit-util.h"
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#include "bus-common-errors.h"
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#include "bus-error.h"
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#include "bus-util.h"
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#include "cgroup-util.h"
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#include "def.h"
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#include "fd-util.h"
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#include "fileio.h"
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#include "format-util.h"
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#include "hostname-util.h"
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#include "login-util.h"
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#include "macro.h"
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#include "parse-util.h"
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#include "path-util.h"
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#include "process-util.h"
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#include "socket-util.h"
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#include "strv.h"
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#include "terminal-util.h"
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#include "util.h"
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static int parse_argv(
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pam_handle_t *handle,
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int argc, const char **argv,
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const char **class,
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const char **type,
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const char **desktop,
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bool *debug) {
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unsigned i;
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assert(argc >= 0);
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assert(argc == 0 || argv);
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for (i = 0; i < (unsigned) argc; i++) {
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if (startswith(argv[i], "class=")) {
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if (class)
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*class = argv[i] + 6;
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} else if (startswith(argv[i], "type=")) {
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if (type)
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*type = argv[i] + 5;
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} else if (startswith(argv[i], "desktop=")) {
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if (desktop)
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*desktop = argv[i] + 8;
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} else if (streq(argv[i], "debug")) {
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if (debug)
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*debug = true;
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} else if (startswith(argv[i], "debug=")) {
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int k;
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k = parse_boolean(argv[i] + 6);
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if (k < 0)
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pam_syslog(handle, LOG_WARNING, "Failed to parse debug= argument, ignoring.");
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else if (debug)
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*debug = k;
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} else
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pam_syslog(handle, LOG_WARNING, "Unknown parameter '%s', ignoring", argv[i]);
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}
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return 0;
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}
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static int get_user_data(
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pam_handle_t *handle,
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const char **ret_username,
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struct passwd **ret_pw) {
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const char *username = NULL;
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struct passwd *pw = NULL;
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int r;
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assert(handle);
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assert(ret_username);
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assert(ret_pw);
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r = pam_get_user(handle, &username, NULL);
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if (r != PAM_SUCCESS) {
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pam_syslog(handle, LOG_ERR, "Failed to get user name.");
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return r;
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}
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if (isempty(username)) {
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pam_syslog(handle, LOG_ERR, "User name not valid.");
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return PAM_AUTH_ERR;
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}
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pw = pam_modutil_getpwnam(handle, username);
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if (!pw) {
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pam_syslog(handle, LOG_ERR, "Failed to get user data.");
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return PAM_USER_UNKNOWN;
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}
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*ret_pw = pw;
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*ret_username = username;
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return PAM_SUCCESS;
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}
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static int socket_from_display(const char *display, char **path) {
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size_t k;
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char *f, *c;
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assert(display);
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assert(path);
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if (!display_is_local(display))
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return -EINVAL;
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k = strspn(display+1, "0123456789");
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f = new(char, STRLEN("/tmp/.X11-unix/X") + k + 1);
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if (!f)
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return -ENOMEM;
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c = stpcpy(f, "/tmp/.X11-unix/X");
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memcpy(c, display+1, k);
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c[k] = 0;
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*path = f;
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return 0;
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}
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static int get_seat_from_display(const char *display, const char **seat, uint32_t *vtnr) {
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union sockaddr_union sa = {
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.un.sun_family = AF_UNIX,
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};
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_cleanup_free_ char *p = NULL, *tty = NULL;
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_cleanup_close_ int fd = -1;
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struct ucred ucred;
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int v, r;
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assert(display);
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assert(vtnr);
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/* We deduce the X11 socket from the display name, then use
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* SO_PEERCRED to determine the X11 server process, ask for
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* the controlling tty of that and if it's a VC then we know
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* the seat and the virtual terminal. Sounds ugly, is only
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* semi-ugly. */
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r = socket_from_display(display, &p);
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if (r < 0)
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return r;
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strncpy(sa.un.sun_path, p, sizeof(sa.un.sun_path)-1);
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fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
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if (fd < 0)
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return -errno;
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if (connect(fd, &sa.sa, SOCKADDR_UN_LEN(sa.un)) < 0)
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return -errno;
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r = getpeercred(fd, &ucred);
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if (r < 0)
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return r;
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r = get_ctty(ucred.pid, NULL, &tty);
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if (r < 0)
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return r;
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v = vtnr_from_tty(tty);
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if (v < 0)
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return v;
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else if (v == 0)
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return -ENOENT;
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if (seat)
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*seat = "seat0";
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*vtnr = (uint32_t) v;
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return 0;
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}
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static int append_session_memory_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
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uint64_t val;
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int r;
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if (isempty(limit))
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return 0;
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if (streq(limit, "infinity")) {
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r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", (uint64_t)-1);
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if (r < 0) {
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pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
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return r;
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}
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} else {
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r = parse_percent(limit);
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if (r >= 0) {
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r = sd_bus_message_append(m, "(sv)", "MemoryMaxScale", "u", (uint32_t) (((uint64_t) UINT32_MAX * r) / 100U));
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if (r < 0) {
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pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
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return r;
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}
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} else {
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r = parse_size(limit, 1024, &val);
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if (r >= 0) {
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r = sd_bus_message_append(m, "(sv)", "MemoryMax", "t", val);
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if (r < 0) {
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pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
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return r;
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}
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} else
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pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.limit: %s, ignoring.", limit);
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}
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}
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return 0;
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}
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static int append_session_tasks_max(pam_handle_t *handle, sd_bus_message *m, const char *limit) {
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uint64_t val;
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int r;
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/* No need to parse "infinity" here, it will be set unconditionally later in manager_start_scope() */
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if (isempty(limit) || streq(limit, "infinity"))
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return 0;
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r = safe_atou64(limit, &val);
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if (r >= 0) {
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r = sd_bus_message_append(m, "(sv)", "TasksMax", "t", val);
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if (r < 0) {
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pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
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return r;
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}
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} else
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pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.limit: %s, ignoring.", limit);
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return 0;
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}
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static int append_session_cg_weight(pam_handle_t *handle, sd_bus_message *m, const char *limit, const char *field) {
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uint64_t val;
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int r;
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if (isempty(limit))
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return 0;
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r = cg_weight_parse(limit, &val);
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if (r >= 0) {
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r = sd_bus_message_append(m, "(sv)", field, "t", val);
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if (r < 0) {
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pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
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return r;
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}
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} else if (streq(field, "CPUWeight"))
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pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.cpu_weight: %s, ignoring.", limit);
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else
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pam_syslog(handle, LOG_WARNING, "Failed to parse systemd.io_weight: %s, ignoring.", limit);
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return 0;
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}
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static const char* getenv_harder(pam_handle_t *handle, const char *key, const char *fallback) {
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const char *v;
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assert(handle);
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assert(key);
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/* Looks for an environment variable, preferrably in the environment block associated with the specified PAM
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* handle, falling back to the process' block instead. */
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v = pam_getenv(handle, key);
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if (!isempty(v))
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return v;
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v = getenv(key);
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if (!isempty(v))
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return v;
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return fallback;
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}
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static int update_environment(pam_handle_t *handle, const char *key, const char *value) {
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int r;
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assert(handle);
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assert(key);
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/* Updates the environment, but only if there's actually a value set. Also, log about errors */
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if (isempty(value))
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return PAM_SUCCESS;
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r = pam_misc_setenv(handle, key, value, 0);
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if (r != PAM_SUCCESS)
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pam_syslog(handle, LOG_ERR, "Failed to set environment variable %s.", key);
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return r;
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}
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_public_ PAM_EXTERN int pam_sm_open_session(
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pam_handle_t *handle,
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int flags,
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int argc, const char **argv) {
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_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
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_cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL, *reply = NULL;
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const char
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*username, *id, *object_path, *runtime_path,
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*service = NULL,
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*tty = NULL, *display = NULL,
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*remote_user = NULL, *remote_host = NULL,
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*seat = NULL,
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*type = NULL, *class = NULL,
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*class_pam = NULL, *type_pam = NULL, *cvtnr = NULL, *desktop = NULL, *desktop_pam = NULL,
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*memory_max = NULL, *tasks_max = NULL, *cpu_weight = NULL, *io_weight = NULL;
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_cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
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int session_fd = -1, existing, r;
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bool debug = false, remote;
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struct passwd *pw;
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uint32_t vtnr = 0;
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uid_t original_uid;
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assert(handle);
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/* Make this a NOP on non-logind systems */
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if (!logind_running())
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return PAM_SUCCESS;
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if (parse_argv(handle,
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argc, argv,
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&class_pam,
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&type_pam,
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&desktop_pam,
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&debug) < 0)
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return PAM_SESSION_ERR;
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if (debug)
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pam_syslog(handle, LOG_DEBUG, "pam-systemd initializing");
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r = get_user_data(handle, &username, &pw);
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if (r != PAM_SUCCESS) {
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pam_syslog(handle, LOG_ERR, "Failed to get user data.");
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return r;
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}
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/* Make sure we don't enter a loop by talking to
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* systemd-logind when it is actually waiting for the
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* background to finish start-up. If the service is
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* "systemd-user" we simply set XDG_RUNTIME_DIR and
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* leave. */
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pam_get_item(handle, PAM_SERVICE, (const void**) &service);
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if (streq_ptr(service, "systemd-user")) {
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_cleanup_free_ char *rt = NULL;
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if (asprintf(&rt, "/run/user/"UID_FMT, pw->pw_uid) < 0)
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return PAM_BUF_ERR;
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r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", rt, 0);
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if (r != PAM_SUCCESS) {
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pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");
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return r;
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}
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return PAM_SUCCESS;
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}
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/* Otherwise, we ask logind to create a session for us */
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pam_get_item(handle, PAM_XDISPLAY, (const void**) &display);
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pam_get_item(handle, PAM_TTY, (const void**) &tty);
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pam_get_item(handle, PAM_RUSER, (const void**) &remote_user);
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pam_get_item(handle, PAM_RHOST, (const void**) &remote_host);
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seat = getenv_harder(handle, "XDG_SEAT", NULL);
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cvtnr = getenv_harder(handle, "XDG_VTNR", NULL);
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type = getenv_harder(handle, "XDG_SESSION_TYPE", type_pam);
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class = getenv_harder(handle, "XDG_SESSION_CLASS", class_pam);
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desktop = getenv_harder(handle, "XDG_SESSION_DESKTOP", desktop_pam);
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tty = strempty(tty);
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if (strchr(tty, ':')) {
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/* A tty with a colon is usually an X11 display, placed there to show up in utmp. We rearrange things
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* and don't pretend that an X display was a tty. */
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if (isempty(display))
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display = tty;
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tty = NULL;
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} else if (streq(tty, "cron")) {
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/* cron is setting PAM_TTY to "cron" for some reason (the commit carries no information why, but
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* probably because it wants to set it to something as pam_time/pam_access/… require PAM_TTY to be set
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* (as they otherwise even try to update it!) — but cron doesn't actually allocate a TTY for its forked
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* off processes.) */
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type = "unspecified";
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class = "background";
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tty = NULL;
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} else if (streq(tty, "ssh")) {
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/* ssh has been setting PAM_TTY to "ssh" (for the same reason as cron does this, see above. For further
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* details look for "PAM_TTY_KLUDGE" in the openssh sources). */
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type ="tty";
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class = "user";
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tty = NULL; /* This one is particularly sad, as this means that ssh sessions — even though usually
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* associated with a pty — won't be tracked by their tty in logind. This is because ssh
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* does the PAM session registration early for new connections, and registers a pty only
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* much later (this is because it doesn't know yet if it needs one at all, as whether to
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* register a pty or not is negotiated much later in the protocol). */
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} else
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/* Chop off leading /dev prefix that some clients specify, but others do not. */
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tty = skip_dev_prefix(tty);
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/* If this fails vtnr will be 0, that's intended */
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if (!isempty(cvtnr))
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(void) safe_atou32(cvtnr, &vtnr);
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if (!isempty(display) && !vtnr) {
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if (isempty(seat))
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(void) get_seat_from_display(display, &seat, &vtnr);
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else if (streq(seat, "seat0"))
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(void) get_seat_from_display(display, NULL, &vtnr);
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}
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if (seat && !streq(seat, "seat0") && vtnr != 0) {
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pam_syslog(handle, LOG_DEBUG, "Ignoring vtnr %"PRIu32" for %s which is not seat0", vtnr, seat);
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vtnr = 0;
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}
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if (isempty(type))
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type = !isempty(display) ? "x11" :
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!isempty(tty) ? "tty" : "unspecified";
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if (isempty(class))
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class = streq(type, "unspecified") ? "background" : "user";
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remote = !isempty(remote_host) && !is_localhost(remote_host);
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(void) pam_get_data(handle, "systemd.memory_max", (const void **)&memory_max);
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(void) pam_get_data(handle, "systemd.tasks_max", (const void **)&tasks_max);
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(void) pam_get_data(handle, "systemd.cpu_weight", (const void **)&cpu_weight);
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(void) pam_get_data(handle, "systemd.io_weight", (const void **)&io_weight);
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/* Talk to logind over the message bus */
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r = sd_bus_open_system(&bus);
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if (r < 0) {
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pam_syslog(handle, LOG_ERR, "Failed to connect to system bus: %s", strerror(-r));
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return PAM_SESSION_ERR;
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}
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if (debug) {
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pam_syslog(handle, LOG_DEBUG, "Asking logind to create session: "
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"uid="UID_FMT" pid="PID_FMT" service=%s type=%s class=%s desktop=%s seat=%s vtnr=%"PRIu32" tty=%s display=%s remote=%s remote_user=%s remote_host=%s",
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pw->pw_uid, getpid_cached(),
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strempty(service),
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type, class, strempty(desktop),
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strempty(seat), vtnr, strempty(tty), strempty(display),
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yes_no(remote), strempty(remote_user), strempty(remote_host));
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pam_syslog(handle, LOG_DEBUG, "Session limits: "
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"memory_max=%s tasks_max=%s cpu_weight=%s io_weight=%s",
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strna(memory_max), strna(tasks_max), strna(cpu_weight), strna(io_weight));
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}
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r = sd_bus_message_new_method_call(
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bus,
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&m,
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"org.freedesktop.login1",
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"/org/freedesktop/login1",
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"org.freedesktop.login1.Manager",
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"CreateSession");
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if (r < 0) {
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pam_syslog(handle, LOG_ERR, "Failed to create CreateSession method call: %s", strerror(-r));
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return PAM_SESSION_ERR;
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}
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r = sd_bus_message_append(m, "uusssssussbss",
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(uint32_t) pw->pw_uid,
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(uint32_t) getpid_cached(),
|
|
service,
|
|
type,
|
|
class,
|
|
desktop,
|
|
seat,
|
|
vtnr,
|
|
tty,
|
|
display,
|
|
remote,
|
|
remote_user,
|
|
remote_host);
|
|
if (r < 0) {
|
|
pam_syslog(handle, LOG_ERR, "Failed to append to bus message: %s", strerror(-r));
|
|
return PAM_SESSION_ERR;
|
|
}
|
|
|
|
r = sd_bus_message_open_container(m, 'a', "(sv)");
|
|
if (r < 0) {
|
|
pam_syslog(handle, LOG_ERR, "Failed to open message container: %s", strerror(-r));
|
|
return PAM_SYSTEM_ERR;
|
|
}
|
|
|
|
r = append_session_memory_max(handle, m, memory_max);
|
|
if (r < 0)
|
|
return PAM_SESSION_ERR;
|
|
|
|
r = append_session_tasks_max(handle, m, tasks_max);
|
|
if (r < 0)
|
|
return PAM_SESSION_ERR;
|
|
|
|
r = append_session_cg_weight(handle, m, cpu_weight, "CPUWeight");
|
|
if (r < 0)
|
|
return PAM_SESSION_ERR;
|
|
|
|
r = append_session_cg_weight(handle, m, io_weight, "IOWeight");
|
|
if (r < 0)
|
|
return PAM_SESSION_ERR;
|
|
|
|
r = sd_bus_message_close_container(m);
|
|
if (r < 0) {
|
|
pam_syslog(handle, LOG_ERR, "Failed to close message container: %s", strerror(-r));
|
|
return PAM_SYSTEM_ERR;
|
|
}
|
|
|
|
r = sd_bus_call(bus, m, 0, &error, &reply);
|
|
if (r < 0) {
|
|
if (sd_bus_error_has_name(&error, BUS_ERROR_SESSION_BUSY)) {
|
|
pam_syslog(handle, LOG_DEBUG, "Cannot create session: %s", bus_error_message(&error, r));
|
|
return PAM_SUCCESS;
|
|
} else {
|
|
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 = update_environment(handle, "XDG_SESSION_ID", id);
|
|
if (r != PAM_SUCCESS)
|
|
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 = update_environment(handle, "XDG_RUNTIME_DIR", runtime_path);
|
|
if (r != PAM_SUCCESS)
|
|
return r;
|
|
}
|
|
|
|
/* Most likely we got the session/type/class from environment variables, but might have gotten the data
|
|
* somewhere else (for example PAM module parameters). Let's now update the environment variables, so that this
|
|
* data is inherited into the session processes, and programs can rely on them to be initialized. */
|
|
|
|
r = update_environment(handle, "XDG_SESSION_TYPE", type);
|
|
if (r != PAM_SUCCESS)
|
|
return r;
|
|
|
|
r = update_environment(handle, "XDG_SESSION_CLASS", class);
|
|
if (r != PAM_SUCCESS)
|
|
return r;
|
|
|
|
r = update_environment(handle, "XDG_SESSION_DESKTOP", desktop);
|
|
if (r != PAM_SUCCESS)
|
|
return r;
|
|
|
|
r = update_environment(handle, "XDG_SEAT", seat);
|
|
if (r != PAM_SUCCESS)
|
|
return r;
|
|
|
|
if (vtnr > 0) {
|
|
char buf[DECIMAL_STR_MAX(vtnr)];
|
|
sprintf(buf, "%u", vtnr);
|
|
|
|
r = update_environment(handle, "XDG_VTNR", buf);
|
|
if (r != PAM_SUCCESS)
|
|
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", FD_TO_PTR(session_fd), 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_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
|
|
_cleanup_(sd_bus_flush_close_unrefp) 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 */
|
|
(void) 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;
|
|
}
|