/* * SPDX-License-Identifier: ISC * * Copyright (c) 2011-2018 Todd C. Miller * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ /* * This is an open source non-commercial project. Dear PVS-Studio, please check it. * PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com */ #include #include #include #include #include #include #if defined(HAVE_UTMPS_H) # include #elif defined(HAVE_UTMPX_H) # include #else # include #endif /* HAVE_UTMPS_H */ #ifdef HAVE_GETTTYENT # include #endif #include #include #include #include /* * GCC 8 warns about strncpy() where the size field is the size of the buffer. * However, strings in utmp may not be NUL terminated so this usage is correct. */ #if __GNUC_PREREQ__(8, 0) # pragma GCC diagnostic ignored "-Wstringop-truncation" #endif /* * Simplify handling of different utmp types. */ #if defined(HAVE_GETUTSID) # define sudo_getutline(u) GETUTSLINE(u) # define sudo_pututline(u) PUTUTSLINE(u) # define sudo_setutent() SETUTSENT() # define sudo_endutent() ENDUTSENT() #elif defined(HAVE_GETUTXID) # define sudo_getutline(u) getutxline(u) # define sudo_pututline(u) pututxline(u) # define sudo_setutent() setutxent() # define sudo_endutent() endutxent() #elif defined(HAVE_GETUTID) # define sudo_getutline(u) getutline(u) # define sudo_pututline(u) pututline(u) # define sudo_setutent() setutent() # define sudo_endutent() endutent() #endif #if defined(HAVE_GETUTSID) typedef struct utmps sudo_utmp_t; #elif defined(HAVE_GETUTXID) typedef struct utmpx sudo_utmp_t; #else typedef struct utmp sudo_utmp_t; /* Older systems have ut_name, not ut_user */ # if !defined(HAVE_STRUCT_UTMP_UT_USER) && !defined(ut_user) # define ut_user ut_name # endif #endif /* HP-UX has __e_termination and __e_exit, others may lack the __ */ #if defined(HAVE_STRUCT_UTMP_UT_EXIT_E_TERMINATION) # undef __e_termination # define __e_termination e_termination # undef __e_exit # define __e_exit e_exit #endif #if defined(HAVE_STRUCT_UTMP_UT_ID) /* * Create ut_id from the new ut_line and the old ut_id. */ static void utmp_setid(sudo_utmp_t *old, sudo_utmp_t *new) { const char *line = new->ut_line; size_t idlen; debug_decl(utmp_setid, SUDO_DEBUG_UTMP); /* Skip over "tty" in the id if old entry did too. */ if (old != NULL) { /* cppcheck-suppress uninitdata */ if (strncmp(line, "tty", 3) == 0) { idlen = MIN(sizeof(old->ut_id), 3); if (strncmp(old->ut_id, "tty", idlen) != 0) line += 3; } } /* Store as much as will fit, skipping parts of the beginning as needed. */ /* cppcheck-suppress uninitdata */ idlen = strlen(line); if (idlen > sizeof(new->ut_id)) { line += idlen - sizeof(new->ut_id); idlen = sizeof(new->ut_id); } strncpy(new->ut_id, line, idlen); debug_return; } #endif /* HAVE_STRUCT_UTMP_UT_ID */ /* * Store time in utmp structure. */ static void utmp_settime(sudo_utmp_t *ut) { struct timeval tv; debug_decl(utmp_settime, SUDO_DEBUG_UTMP); if (gettimeofday(&tv, NULL) == 0) { #if defined(HAVE_STRUCT_UTMP_UT_TV) ut->ut_tv.tv_sec = tv.tv_sec; ut->ut_tv.tv_usec = tv.tv_usec; #else ut->ut_time = tv.tv_sec; #endif } debug_return; } /* * Fill in a utmp entry, using an old entry as a template if there is one. */ static void utmp_fill(const char *line, const char *user, sudo_utmp_t *ut_old, sudo_utmp_t *ut_new) { debug_decl(utmp_file, SUDO_DEBUG_UTMP); if (ut_old == NULL) { memset(ut_new, 0, sizeof(*ut_new)); } else if (ut_old != ut_new) { memcpy(ut_new, ut_old, sizeof(*ut_new)); } strncpy(ut_new->ut_user, user, sizeof(ut_new->ut_user)); strncpy(ut_new->ut_line, line, sizeof(ut_new->ut_line)); #if defined(HAVE_STRUCT_UTMP_UT_ID) utmp_setid(ut_old, ut_new); #endif #if defined(HAVE_STRUCT_UTMP_UT_PID) ut_new->ut_pid = getpid(); #endif utmp_settime(ut_new); #if defined(HAVE_STRUCT_UTMP_UT_TYPE) ut_new->ut_type = USER_PROCESS; #endif debug_return; } /* * There are two basic utmp file types: * * POSIX: sequential access with new entries appended to the end. * Manipulated via {get,put}[sx]?utent() * * Legacy: sparse file indexed by ttyslot() * sizeof(struct utmp) */ #if defined(HAVE_GETUTSID) || defined(HAVE_GETUTXID) || defined(HAVE_GETUTID) bool utmp_login(const char *from_line, const char *to_line, int ttyfd, const char *user) { sudo_utmp_t utbuf, *ut_old = NULL; bool ret = false; debug_decl(utmp_login, SUDO_DEBUG_UTMP); /* Strip off /dev/ prefix from line as needed. */ if (strncmp(to_line, _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0) to_line += sizeof(_PATH_DEV) - 1; sudo_setutent(); if (from_line != NULL) { if (strncmp(from_line, _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0) from_line += sizeof(_PATH_DEV) - 1; /* Lookup old line. */ memset(&utbuf, 0, sizeof(utbuf)); strncpy(utbuf.ut_line, from_line, sizeof(utbuf.ut_line)); ut_old = sudo_getutline(&utbuf); sudo_setutent(); } utmp_fill(to_line, user, ut_old, &utbuf); if (sudo_pututline(&utbuf) != NULL) ret = true; sudo_endutent(); debug_return_bool(ret); } bool utmp_logout(const char *line, int status) { bool ret = false; sudo_utmp_t *ut, utbuf; debug_decl(utmp_logout, SUDO_DEBUG_UTMP); /* Strip off /dev/ prefix from line as needed. */ if (strncmp(line, _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0) line += sizeof(_PATH_DEV) - 1; memset(&utbuf, 0, sizeof(utbuf)); strncpy(utbuf.ut_line, line, sizeof(utbuf.ut_line)); if ((ut = sudo_getutline(&utbuf)) != NULL) { memset(ut->ut_user, 0, sizeof(ut->ut_user)); # if defined(HAVE_STRUCT_UTMP_UT_TYPE) ut->ut_type = DEAD_PROCESS; # endif # if defined(HAVE_STRUCT_UTMP_UT_EXIT) ut->ut_exit.__e_termination = WIFSIGNALED(status) ? WTERMSIG(status) : 0; ut->ut_exit.__e_exit = WIFEXITED(status) ? WEXITSTATUS(status) : 0; # endif utmp_settime(ut); if (sudo_pututline(ut) != NULL) ret = true; } debug_return_bool(ret); } #else /* !HAVE_GETUTSID && !HAVE_GETUTXID && !HAVE_GETUTID */ /* * Find the slot for the specified line (tty name and file descriptor). * Returns a slot suitable for seeking into utmp on success or <= 0 on error. * If getttyent() is available we can use that to compute the slot. */ # ifdef HAVE_GETTTYENT static int utmp_slot(const char *line, int ttyfd) { int slot = 1; struct ttyent *tty; debug_decl(utmp_slot, SUDO_DEBUG_UTMP); setttyent(); while ((tty = getttyent()) != NULL) { if (strcmp(line, tty->ty_name) == 0) break; slot++; } endttyent(); debug_return_int(tty ? slot : 0); } # elif defined(HAVE_TTYSLOT) static int utmp_slot(const char *line, int ttyfd) { int sfd, slot; debug_decl(utmp_slot, SUDO_DEBUG_UTMP); /* * Temporarily point stdin to the tty since ttyslot() * doesn't take an argument. */ if ((sfd = dup(STDIN_FILENO)) == -1) sudo_fatal("%s", U_("unable to save stdin")); if (dup2(ttyfd, STDIN_FILENO) == -1) sudo_fatal("%s", U_("unable to dup2 stdin")); slot = ttyslot(); if (dup2(sfd, STDIN_FILENO) == -1) sudo_fatal("%s", U_("unable to restore stdin")); close(sfd); debug_return_int(slot); } # else /* !HAVE_TTYSLOT */ static int utmp_slot(const char *line, int ttyfd) { return -1; } # endif /* HAVE_GETTTYENT */ bool utmp_login(const char *from_line, const char *to_line, int ttyfd, const char *user) { sudo_utmp_t utbuf, *ut_old = NULL; bool ret = false; int slot; FILE *fp; debug_decl(utmp_login, SUDO_DEBUG_UTMP); /* Strip off /dev/ prefix from line as needed. */ if (strncmp(to_line, _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0) to_line += sizeof(_PATH_DEV) - 1; /* Find slot for new entry. */ slot = utmp_slot(to_line, ttyfd); if (slot <= 0) goto done; if ((fp = fopen(_PATH_UTMP, "r+")) == NULL) goto done; if (from_line != NULL) { if (strncmp(from_line, _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0) from_line += sizeof(_PATH_DEV) - 1; /* Lookup old line. */ while (fread(&utbuf, sizeof(utbuf), 1, fp) == 1) { # ifdef HAVE_STRUCT_UTMP_UT_ID if (utbuf.ut_type != LOGIN_PROCESS && utbuf.ut_type != USER_PROCESS) continue; # endif if (utbuf.ut_user[0] && !strncmp(utbuf.ut_line, from_line, sizeof(utbuf.ut_line))) { ut_old = &utbuf; break; } } } utmp_fill(to_line, user, ut_old, &utbuf); if (fseeko(fp, slot * (off_t)sizeof(utbuf), SEEK_SET) == 0) { if (fwrite(&utbuf, sizeof(utbuf), 1, fp) == 1) ret = true; } fclose(fp); done: debug_return_bool(ret); } bool utmp_logout(const char *line, int status) { sudo_utmp_t utbuf; bool ret = false; FILE *fp; debug_decl(utmp_logout, SUDO_DEBUG_UTMP); if ((fp = fopen(_PATH_UTMP, "r+")) == NULL) debug_return_int(ret); /* Strip off /dev/ prefix from line as needed. */ if (strncmp(line, _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0) line += sizeof(_PATH_DEV) - 1; while (fread(&utbuf, sizeof(utbuf), 1, fp) == 1) { if (!strncmp(utbuf.ut_line, line, sizeof(utbuf.ut_line))) { memset(utbuf.ut_user, 0, sizeof(utbuf.ut_user)); # if defined(HAVE_STRUCT_UTMP_UT_TYPE) utbuf.ut_type = DEAD_PROCESS; # endif utmp_settime(&utbuf); /* Back up and overwrite record. */ if (fseeko(fp, (off_t)0 - (off_t)sizeof(utbuf), SEEK_CUR) == 0) { if (fwrite(&utbuf, sizeof(utbuf), 1, fp) == 1) ret = true; } break; } } fclose(fp); debug_return_bool(ret); } #endif /* HAVE_GETUTSID || HAVE_GETUTXID || HAVE_GETUTID */