/* * Copyright (c) 1996, 1998-2005 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. * * Sponsored in part by the Defense Advanced Research Projects * Agency (DARPA) and Air Force Research Laboratory, Air Force * Materiel Command, USAF, under agreement number F39502-99-1-0512. */ /* * Lock the sudoers file for safe editing (ala vipw) and check for parse errors. */ #define _SUDO_MAIN #ifdef __TANDEM # include #endif #include #include #include #include #include #ifndef __TANDEM # include #endif #include #include #ifdef STDC_HEADERS # include # include #else # ifdef HAVE_STDLIB_H # include # endif #endif /* STDC_HEADERS */ #ifdef HAVE_STRING_H # include #else # ifdef HAVE_STRINGS_H # include # endif #endif /* HAVE_STRING_H */ #ifdef HAVE_UNISTD_H #include #endif /* HAVE_UNISTD_H */ #ifdef HAVE_ERR_H # include #else # include "emul/err.h" #endif /* HAVE_ERR_H */ #include #include #if TIME_WITH_SYS_TIME # include #endif #include #include #include #ifndef HAVE_TIMESPEC # include #endif #include "sudo.h" #include "version.h" #ifndef lint __unused static const char rcsid[] = "$Sudo: visudo.c,v 1.166.2.10 2007/09/01 13:39:13 millert Exp $"; #endif /* lint */ struct sudoersfile { char *path; char *tpath; int fd; off_t orig_size; struct timespec orig_mtim; }; /* * Function prototypes */ static void usage __P((void)) __attribute__((__noreturn__)); static char whatnow __P((void)); static RETSIGTYPE Exit __P((int)); static void edit_sudoers __P((struct sudoersfile *, char *, char *, int)); static void visudo __P((struct sudoersfile *, char *, char *)); static void setup_signals __P((void)); static void install_sudoers __P((struct sudoersfile *, int)); static int check_syntax __P(()); static int run_command __P((char *, char **)); static char *get_args __P((char *)); static char *get_editor __P((char **)); static FILE *open_sudoers __P((struct sudoersfile *)); int command_matches __P((char *, char *)); int addr_matches __P((char *)); int hostname_matches __P((char *, char *, char *)); int netgr_matches __P((char *, char *, char *, char *)); int usergr_matches __P((char *, char *, struct passwd *)); int userpw_matches __P((char *, char *, struct passwd *)); void init_parser __P((void)); void yyerror __P((char *)); void yyrestart __P((FILE *)); /* * External globals exported by the parser */ extern FILE *yyin; extern int errorlineno; extern int pedantic; extern int quiet; /* For getopt(3) */ extern char *optarg; extern int optind; /* * Globals */ char **Argv; struct sudo_user sudo_user; int Argc, parse_error = FALSE; static struct sudoersfile sudoers; int main(argc, argv) int argc; char **argv; { char *args, *editor; int ch, checkonly, n, oldperms; /* Initialize sudoers struct. */ sudoers.path = _PATH_SUDOERS; sudoers.tpath = _PATH_SUDOERS_TMP; sudoers.fd = -1; /* Warn about aliases that are used before being defined. */ pedantic = 1; Argv = argv; if ((Argc = argc) < 1) usage(); /* * Arg handling. */ checkonly = oldperms = FALSE; while ((ch = getopt(argc, argv, "Vcf:sq")) != -1) { switch (ch) { case 'V': (void) printf("%s version %s\n", getprogname(), version); exit(0); case 'c': checkonly++; /* check mode */ break; case 'f': /* sudoers file path */ sudoers.path = optarg; easprintf(&sudoers.tpath, "%s.tmp", optarg); oldperms = TRUE; break; case 's': pedantic++; /* strict mode */ break; case 'q': quiet++; /* quiet mode */ break; default: usage(); } } argc -= optind; argv += optind; if (argc) usage(); /* Mock up a fake sudo_user struct. */ user_host = user_shost = user_cmnd = ""; if ((sudo_user.pw = getpwuid(getuid())) == NULL) errx(1, "you don't exist in the passwd database"); /* Setup defaults data structures. */ init_defaults(); if (checkonly) exit(check_syntax()); /* * Open and parse the existing sudoers file(s) in quiet mode to highlight * any existing errors and to pull in editor and env_editor conf values. */ if ((yyin = open_sudoers(&sudoers)) == NULL) err(1, "%s", sudoers.path); n = quiet; quiet = 1; init_parser(); yyparse(); parse_error = FALSE; quiet = n; /* Edit sudoers, check for parse errors and re-edit on failure. */ editor = get_editor(&args); visudo(&sudoers, editor, args); /* Install the new sudoers file. */ install_sudoers(&sudoers, oldperms); exit(0); } /* * Edit the sudoers file. * Returns TRUE on success, else FALSE. */ static void edit_sudoers(sp, editor, args, lineno) struct sudoersfile *sp; char *editor, *args; int lineno; { int ac; /* argument count */ char **av; /* argument vector for run_command */ char *cp; /* scratch char pointer */ char linestr[64]; /* string version of lineno */ struct timespec ts1, ts2; /* time before and after edit */ struct stat sb; /* stat buffer */ /* Make timestamp on temp file match original. */ (void) touch(-1, sp->tpath, &sp->orig_mtim); /* Find the length of the argument vector */ ac = 3 + (lineno > 0); if (args) { int wasblank; ac++; for (wasblank = FALSE, cp = args; *cp; cp++) { if (isblank((unsigned char) *cp)) wasblank = TRUE; else if (wasblank) { wasblank = FALSE; ac++; } } } /* Build up argument vector for the command */ av = emalloc2(ac, sizeof(char *)); if ((av[0] = strrchr(editor, '/')) != NULL) av[0]++; else av[0] = editor; ac = 1; if (lineno > 0) { (void) snprintf(linestr, sizeof(linestr), "+%d", lineno); av[ac++] = linestr; } if (args) { for ((cp = strtok(args, " \t")); cp; (cp = strtok(NULL, " \t"))) av[ac++] = cp; } av[ac++] = sp->tpath; av[ac++] = NULL; /* * Do the edit: * We cannot check the editor's exit value against 0 since * XPG4 specifies that vi's exit value is a function of the * number of errors during editing (?!?!). */ gettime(&ts1); if (run_command(editor, av) != -1) { gettime(&ts2); /* * Sanity checks. */ if (stat(sp->tpath, &sb) < 0) { warnx("cannot stat temporary file (%s), %s unchanged", sp->tpath, sp->path); Exit(-1); } if (sb.st_size == 0) { warnx("zero length temporary file (%s), %s unchanged", sp->tpath, sp->path); Exit(-1); } } else { warnx("editor (%s) failed, %s unchanged", editor, sp->path); Exit(-1); } /* Check to see if the user changed the file. */ if (sp->orig_size == sb.st_size && sp->orig_mtim.tv_sec == mtim_getsec(sb) && sp->orig_mtim.tv_nsec == mtim_getnsec(sb)) { /* * If mtime and size match but the user spent no measurable * time in the editor we can't tell if the file was changed. */ #ifdef HAVE_TIMESPECSUB2 timespecsub(&ts1, &ts2); #else timespecsub(&ts1, &ts2, &ts2); #endif if (timespecisset(&ts2)) { warnx("%s unchanged", sp->tpath); Exit(0); } } } /* * Parse sudoers after editing and re-edit any ones that caused a parse error. * Returns TRUE on success, else FALSE. */ static void visudo(sp, editor, args) struct sudoersfile *sp; char *editor, *args; { int ch; /* * Parse the edited sudoers file and do sanity checking */ do { edit_sudoers(sp, editor, args, errorlineno); yyin = fopen(sp->tpath, "r+"); if (yyin == NULL) { warnx("can't re-open temporary file (%s), %s unchanged.", sp->tpath, sp->path); Exit(-1); } /* Add missing newline at EOF if needed. */ if (fseek(yyin, -1, SEEK_END) == 0 && (ch = fgetc(yyin)) != '\n') fputc('\n', yyin); rewind(yyin); /* Clean slate for each parse */ user_runas = NULL; init_defaults(); init_parser(); /* Parse the sudoers temp file */ yyrestart(yyin); if (yyparse() && parse_error != TRUE) { warnx("unabled to parse temporary file (%s), unknown error", sp->tpath); parse_error = TRUE; } fclose(yyin); /* * Got an error, prompt the user for what to do now */ if (parse_error) { switch (whatnow()) { case 'Q' : parse_error = FALSE; /* ignore parse error */ break; case 'x' : Exit(0); break; } } } while (parse_error); } /* * Set the owner and mode on a sudoers temp file and * move it into place. Returns TRUE on success, else FALSE. */ static void install_sudoers(sp, oldperms) struct sudoersfile *sp; int oldperms; { struct stat sb; /* * Change mode and ownership of temp file so when * we move it to sp->path things are kosher. */ if (oldperms) { /* Use perms of the existing file. */ #ifdef HAVE_FSTAT if (fstat(sp->fd, &sb) == -1) #else if (stat(sp->path, &sb) == -1) #endif err(1, "can't stat %s", sp->path); (void) chown(sp->tpath, sb.st_uid, sb.st_gid); (void) chmod(sp->tpath, sb.st_mode & 0777); } else { if (chown(sp->tpath, SUDOERS_UID, SUDOERS_GID) != 0) { warn("unable to set (uid, gid) of %s to (%d, %d)", sp->tpath, SUDOERS_UID, SUDOERS_GID); Exit(-1); } if (chmod(sp->tpath, SUDOERS_MODE) != 0) { warn("unable to change mode of %s to 0%o", sp->tpath, SUDOERS_MODE); Exit(-1); } } /* * Now that sp->tpath is sane (parses ok) it needs to be * rename(2)'d to sp->path. If the rename(2) fails we try using * mv(1) in case sp->tpath and sp->path are on different file systems. */ if (rename(sp->tpath, sp->path) != 0) { if (errno == EXDEV) { char *av[4]; warnx("%s and %s not on the same file system, using mv to rename", sp->tpath, sp->path); /* Build up argument vector for the command */ if ((av[0] = strrchr(_PATH_MV, '/')) != NULL) av[0]++; else av[0] = _PATH_MV; av[1] = sp->tpath; av[2] = sp->path; av[3] = NULL; /* And run it... */ if (run_command(_PATH_MV, av)) { warnx("command failed: '%s %s %s', %s unchanged", _PATH_MV, sp->tpath, sp->path, sp->path); Exit(-1); } } else { warn("error renaming %s, %s unchanged", sp->tpath, sp->path); Exit(-1); } } } /* * Dummy *_matches routines. * These exist to allow us to use the same parser as sudo(8). */ int command_matches(path, sudoers_args) char *path; char *sudoers_args; { return(TRUE); } int addr_matches(n) char *n; { return(TRUE); } int hostname_matches(s, l, p) char *s, *l, *p; { return(TRUE); } int usergr_matches(g, u, pw) char *g, *u; struct passwd *pw; { return(TRUE); } int userpw_matches(s, u, pw) char *s, *u; struct passwd *pw; { return(TRUE); } int netgr_matches(n, h, sh, u) char *n, *h, *sh, *u; { return(TRUE); } void set_fqdn() { return; } int set_runaspw(user) char *user; { extern int sudolineno, used_runas; if (used_runas) { (void) fprintf(stderr, "%s: runas_default set after old value is in use near line %d\n", pedantic > 1 ? "Error" : "Warning", sudolineno); if (pedantic > 1) yyerror(NULL); } return(TRUE); } int user_is_exempt() { return(TRUE); } void init_envtables() { return; } /* * Assuming a parse error occurred, prompt the user for what they want * to do now. Returns the first letter of their choice. */ static char whatnow() { int choice, c; for (;;) { (void) fputs("What now? ", stdout); choice = getchar(); for (c = choice; c != '\n' && c != EOF;) c = getchar(); switch (choice) { case EOF: choice = 'x'; /* FALLTHROUGH */ case 'e': case 'x': case 'Q': return(choice); default: (void) puts("Options are:"); (void) puts(" (e)dit sudoers file again"); (void) puts(" e(x)it without saving changes to sudoers file"); (void) puts(" (Q)uit and save changes to sudoers file (DANGER!)\n"); } } } /* * Install signal handlers for visudo. */ static void setup_signals() { sigaction_t sa; /* * Setup signal handlers to cleanup nicely. */ sigemptyset(&sa.sa_mask); sa.sa_flags = SA_RESTART; sa.sa_handler = Exit; (void) sigaction(SIGTERM, &sa, NULL); (void) sigaction(SIGHUP, &sa, NULL); (void) sigaction(SIGINT, &sa, NULL); (void) sigaction(SIGQUIT, &sa, NULL); } static int run_command(path, argv) char *path; char **argv; { int status; pid_t pid; sigset_t set, oset; (void) sigemptyset(&set); (void) sigaddset(&set, SIGCHLD); (void) sigprocmask(SIG_BLOCK, &set, &oset); switch (pid = fork()) { case -1: warn("unable to run %s", path); Exit(-1); break; /* NOTREACHED */ case 0: (void) sigprocmask(SIG_SETMASK, &oset, NULL); endpwent(); closefrom(STDERR_FILENO + 1); execv(path, argv); warn("unable to run %s", path); _exit(127); break; /* NOTREACHED */ } #ifdef sudo_waitpid pid = sudo_waitpid(pid, &status, 0); #else pid = wait(&status); #endif (void) sigprocmask(SIG_SETMASK, &oset, NULL); if (pid == -1 || !WIFEXITED(status)) return(-1); return(WEXITSTATUS(status)); } static int check_syntax() { if ((yyin = fopen(sudoers.path, "r")) == NULL) { if (!quiet) warn("unable to open %s", sudoers.path); exit(1); } init_parser(); if (yyparse() && parse_error != TRUE) { if (!quiet) warnx("failed to parse %s file, unknown error", sudoers.path); parse_error = TRUE; } if (!quiet){ if (parse_error) (void) printf("parse error in %s near line %d\n", sudoers.path, errorlineno); else (void) printf("%s file parsed OK\n", sudoers.path); } return(parse_error == TRUE); } static FILE * open_sudoers(sp) struct sudoersfile *sp; { struct stat sb; ssize_t nread; FILE *fp; char buf[PATH_MAX*2]; int tfd; /* Open and lock sudoers. */ sp->fd = open(sp->path, O_RDWR | O_CREAT, SUDOERS_MODE); if (sp->fd == -1) err(1, "%s", sp->path); if (!lock_file(sp->fd, SUDO_TLOCK)) errx(1, "%s busy, try again later", sp->path); if ((fp = fdopen(sp->fd, "r")) == NULL) err(1, "%s", sp->path); /* Stash sudoers size and mtime. */ #ifdef HAVE_FSTAT if (fstat(sp->fd, &sb) == -1) #else if (stat(sp->path, &sb) == -1) #endif err(1, "can't stat %s", sp->path); sp->orig_size = sb.st_size; sp->orig_mtim.tv_sec = mtim_getsec(sb); sp->orig_mtim.tv_nsec = mtim_getnsec(sb); /* Create the temp file. */ tfd = open(sp->tpath, O_WRONLY | O_CREAT | O_TRUNC, 0600); if (tfd < 0) err(1, "%s", sp->tpath); /* Install signal handlers to clean up temp file if we are killed. */ setup_signals(); /* Copy sp->path -> sp->tpath. */ if (sp->orig_size != 0) { while ((nread = read(sp->fd, buf, sizeof(buf))) > 0) if (write(tfd, buf, nread) != nread) { warn("write error"); Exit(-1); } /* Add missing newline at EOF if needed. */ if (nread > 0 && buf[nread - 1] != '\n') { buf[0] = '\n'; write(tfd, buf, 1); } } (void) close(tfd); rewind(fp); return(fp); } static char * get_editor(args) char **args; { char *Editor, *EditorArgs, *EditorPath, *UserEditor, *UserEditorArgs; /* * Check VISUAL and EDITOR environment variables to see which editor * the user wants to use (we may not end up using it though). * If the path is not fully-qualified, make it so and check that * the specified executable actually exists. */ UserEditorArgs = NULL; if ((UserEditor = getenv("VISUAL")) == NULL || *UserEditor == '\0') UserEditor = getenv("EDITOR"); if (UserEditor && *UserEditor == '\0') UserEditor = NULL; else if (UserEditor) { UserEditorArgs = get_args(UserEditor); if (find_path(UserEditor, &Editor, NULL, getenv("PATH")) == FOUND) { UserEditor = Editor; } else { if (def_env_editor) { /* If we are honoring $EDITOR this is a fatal error. */ warnx("specified editor (%s) doesn't exist!", UserEditor); Exit(-1); } else { /* Otherwise, just ignore $EDITOR. */ UserEditor = NULL; } } } /* * See if we can use the user's choice of editors either because * we allow any $EDITOR or because $EDITOR is in the allowable list. */ Editor = EditorArgs = EditorPath = NULL; if (def_env_editor && UserEditor) { Editor = UserEditor; EditorArgs = UserEditorArgs; } else if (UserEditor) { struct stat editor_sb; struct stat user_editor_sb; char *base, *userbase; if (stat(UserEditor, &user_editor_sb) != 0) { /* Should never happen since we already checked above. */ warn("unable to stat editor (%s)", UserEditor); Exit(-1); } EditorPath = estrdup(def_editor); Editor = strtok(EditorPath, ":"); do { EditorArgs = get_args(Editor); /* * Both Editor and UserEditor should be fully qualified but * check anyway... */ if ((base = strrchr(Editor, '/')) == NULL) continue; if ((userbase = strrchr(UserEditor, '/')) == NULL) { Editor = NULL; break; } base++, userbase++; /* * We compare the basenames first and then use stat to match * for sure. */ if (strcmp(base, userbase) == 0) { if (stat(Editor, &editor_sb) == 0 && S_ISREG(editor_sb.st_mode) && (editor_sb.st_mode & 0000111) && editor_sb.st_dev == user_editor_sb.st_dev && editor_sb.st_ino == user_editor_sb.st_ino) break; } } while ((Editor = strtok(NULL, ":"))); } /* * Can't use $EDITOR, try each element of def_editor until we * find one that exists, is regular, and is executable. */ if (Editor == NULL || *Editor == '\0') { efree(EditorPath); EditorPath = estrdup(def_editor); Editor = strtok(EditorPath, ":"); do { EditorArgs = get_args(Editor); if (sudo_goodpath(Editor, NULL)) break; } while ((Editor = strtok(NULL, ":"))); /* Bleah, none of the editors existed! */ if (Editor == NULL || *Editor == '\0') { warnx("no editor found (editor path = %s)", def_editor); Exit(-1); } } *args = EditorArgs; return(Editor); } /* * Split out any command line arguments and return them. */ static char * get_args(cmnd) char *cmnd; { char *args; args = cmnd; while (*args && !isblank((unsigned char) *args)) args++; if (*args) { *args++ = '\0'; while (*args && isblank((unsigned char) *args)) args++; } return(*args ? args : NULL); } /* * Unlink the sudoers temp file (if it exists) and exit. * Used in place of a normal exit() and as a signal handler. * A positive parameter indicates we were called as a signal handler. */ static RETSIGTYPE Exit(sig) int sig; { #define emsg " exiting due to signal.\n" (void) unlink(sudoers.tpath); if (sig > 0) { write(STDERR_FILENO, getprogname(), strlen(getprogname())); write(STDERR_FILENO, emsg, sizeof(emsg) - 1); _exit(sig); } exit(-sig); } static void usage() { (void) fprintf(stderr, "usage: %s [-c] [-q] [-s] [-V] [-f sudoers]\n", getprogname()); exit(1); }