[2725] | 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * utmp/wtmp support routines.
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| 4 | *
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| 5 | * Copyright (C) 2010 Denys Vlasenko
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| 6 | *
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| 7 | * Licensed under GPLv2, see file LICENSE in this source tree.
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| 8 | */
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| 9 | #include "libbb.h"
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| 10 |
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| 11 | static void touch(const char *filename)
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| 12 | {
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| 13 | if (access(filename, R_OK | W_OK) == -1)
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| 14 | close(open(filename, O_WRONLY | O_CREAT, 0664));
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| 15 | }
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| 16 |
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| 17 | void FAST_FUNC write_new_utmp(pid_t pid, int new_type, const char *tty_name, const char *username, const char *hostname)
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| 18 | {
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[3621] | 19 | struct utmpx utent;
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[2725] | 20 | char *id;
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| 21 | unsigned width;
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| 22 |
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| 23 | memset(&utent, 0, sizeof(utent));
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| 24 | utent.ut_pid = pid;
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| 25 | utent.ut_type = new_type;
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| 26 | tty_name = skip_dev_pfx(tty_name);
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| 27 | safe_strncpy(utent.ut_line, tty_name, sizeof(utent.ut_line));
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| 28 | if (username)
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| 29 | safe_strncpy(utent.ut_user, username, sizeof(utent.ut_user));
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| 30 | if (hostname)
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| 31 | safe_strncpy(utent.ut_host, hostname, sizeof(utent.ut_host));
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| 32 | utent.ut_tv.tv_sec = time(NULL);
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| 33 |
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| 34 | /* Invent our own ut_id. ut_id is only 4 chars wide.
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| 35 | * Try to fit something remotely meaningful... */
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| 36 | id = utent.ut_id;
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| 37 | width = sizeof(utent.ut_id);
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| 38 | if (tty_name[0] == 'p') {
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| 39 | /* if "ptyXXX", map to "pXXX" */
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| 40 | /* if "pts/XX", map to "p/XX" */
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| 41 | *id++ = 'p';
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| 42 | width--;
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| 43 | } /* else: usually it's "ttyXXXX", map to "XXXX" */
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| 44 | if (strlen(tty_name) > 3)
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| 45 | tty_name += 3;
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| 46 | strncpy(id, tty_name, width);
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| 47 |
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[3621] | 48 | touch(_PATH_UTMPX);
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| 49 | //utmpxname(_PATH_UTMPX);
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| 50 | setutxent();
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[2725] | 51 | /* Append new one (hopefully, unless we collide on ut_id) */
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[3621] | 52 | pututxline(&utent);
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| 53 | endutxent();
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[2725] | 54 |
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| 55 | #if ENABLE_FEATURE_WTMP
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| 56 | /* "man utmp" says wtmp file should *not* be created automagically */
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| 57 | /*touch(bb_path_wtmp_file);*/
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[3621] | 58 | updwtmpx(bb_path_wtmp_file, &utent);
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[2725] | 59 | #endif
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| 60 | }
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| 61 |
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| 62 | /*
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| 63 | * Read "man utmp" to make sense out of it.
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| 64 | */
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| 65 | void FAST_FUNC update_utmp(pid_t pid, int new_type, const char *tty_name, const char *username, const char *hostname)
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| 66 | {
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[3621] | 67 | struct utmpx utent;
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| 68 | struct utmpx *utp;
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[2725] | 69 |
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[3621] | 70 | touch(_PATH_UTMPX);
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| 71 | //utmpxname(_PATH_UTMPX);
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| 72 | setutxent();
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[2725] | 73 |
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| 74 | /* Did init/getty/telnetd/sshd/... create an entry for us?
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| 75 | * It should be (new_type-1), but we'd also reuse
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| 76 | * any other potentially stale xxx_PROCESS entry */
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[3621] | 77 | while ((utp = getutxent()) != NULL) {
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[2725] | 78 | if (utp->ut_pid == pid
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| 79 | // && ut->ut_line[0]
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| 80 | && utp->ut_id[0] /* must have nonzero id */
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| 81 | && ( utp->ut_type == INIT_PROCESS
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| 82 | || utp->ut_type == LOGIN_PROCESS
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| 83 | || utp->ut_type == USER_PROCESS
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| 84 | || utp->ut_type == DEAD_PROCESS
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| 85 | )
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| 86 | ) {
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| 87 | if (utp->ut_type >= new_type) {
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| 88 | /* Stale record. Nuke hostname */
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| 89 | memset(utp->ut_host, 0, sizeof(utp->ut_host));
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| 90 | }
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[3621] | 91 | /* NB: pututxline (see later) searches for matching utxent
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| 92 | * using getutxid(utent) - we must not change ut_id
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[2725] | 93 | * if we want *exactly this* record to be overwritten!
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| 94 | */
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| 95 | break;
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| 96 | }
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| 97 | }
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[3621] | 98 | //endutxent(); - no need, pututxline can deal with (and actually likes)
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[2725] | 99 | //the situation when utmp file is positioned on found record
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| 100 |
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| 101 | if (!utp) {
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| 102 | if (new_type != DEAD_PROCESS)
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| 103 | write_new_utmp(pid, new_type, tty_name, username, hostname);
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| 104 | else
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[3621] | 105 | endutxent();
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[2725] | 106 | return;
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| 107 | }
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| 108 |
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[3621] | 109 | /* Make a copy. We can't use *utp, pututxline's internal getutxid
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[2725] | 110 | * will overwrite it before it is used! */
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| 111 | utent = *utp;
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| 112 |
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| 113 | utent.ut_type = new_type;
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| 114 | if (tty_name)
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| 115 | safe_strncpy(utent.ut_line, skip_dev_pfx(tty_name), sizeof(utent.ut_line));
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| 116 | if (username)
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| 117 | safe_strncpy(utent.ut_user, username, sizeof(utent.ut_user));
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| 118 | if (hostname)
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| 119 | safe_strncpy(utent.ut_host, hostname, sizeof(utent.ut_host));
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| 120 | utent.ut_tv.tv_sec = time(NULL);
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| 121 |
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| 122 | /* Update, or append new one */
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[3621] | 123 | //setutxent();
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| 124 | pututxline(&utent);
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| 125 | endutxent();
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[2725] | 126 |
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| 127 | #if ENABLE_FEATURE_WTMP
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| 128 | /* "man utmp" says wtmp file should *not* be created automagically */
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| 129 | /*touch(bb_path_wtmp_file);*/
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[3621] | 130 | updwtmpx(bb_path_wtmp_file, &utent);
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[2725] | 131 | #endif
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| 132 | }
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[3621] | 133 |
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| 134 | /* man utmp:
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| 135 | * When init(8) finds that a process has exited, it locates its utmp entry
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| 136 | * by ut_pid, sets ut_type to DEAD_PROCESS, and clears ut_user, ut_host
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| 137 | * and ut_time with null bytes.
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| 138 | * [same applies to other processes which maintain utmp entries, like telnetd]
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| 139 | *
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| 140 | * We do not bother actually clearing fields:
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| 141 | * it might be interesting to know who was logged in and from where
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| 142 | */
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| 143 | void FAST_FUNC update_utmp_DEAD_PROCESS(pid_t pid)
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| 144 | {
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| 145 | update_utmp(pid, DEAD_PROCESS, NULL, NULL, NULL);
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| 146 | }
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