diff options
Diffstat (limited to 'login-utils/setpwnam.c')
| -rw-r--r-- | login-utils/setpwnam.c | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/login-utils/setpwnam.c b/login-utils/setpwnam.c new file mode 100644 index 0000000..3e3c1ab --- /dev/null +++ b/login-utils/setpwnam.c @@ -0,0 +1,216 @@ +/* + * setpwnam.c -- edit an entry in a password database. + * + * (c) 1994 Salvatore Valente <svalente@mit.edu> + * This file is free software; you can redistribute it and/or + * modify it under the terms of the GNU Library General Public License as + * published by the Free Software Foundation; either version 2 of the + * License, or (at your option) any later version. + * + * Edited 11/10/96 (DD/MM/YY ;-) by Nicolai Langfeldt (janl@math.uio.no) + * to read /etc/passwd directly so that passwd, chsh and chfn can work on + * machines that run NIS (previously YP). Changes will not be made to + * usernames starting with +. + * + * This file is distributed with no warranty. + * + * Usage: + * 1) get a struct passwd * from getpwnam(). + * You should assume a struct passwd has an infinite number of fields, so + * you should not try to create one from scratch. + * 2) edit the fields you want to edit. + * 3) call setpwnam() with the edited struct passwd. + * + * A _normal user_ program should never directly manipulate etc/passwd but + * /use getpwnam() and (family, as well as) setpwnam(). + * + * But, setpwnam was made to _edit_ the password file. For use by chfn, + * chsh and passwd. _I_ _HAVE_ to read and write /etc/passwd directly. Let + * those who say nay be forever silent and think about how getpwnam (and + * family) works on a machine running YP. + * + * Added checks for failure of malloc() and removed error reporting to + * stderr, this is a library function and should not print on the screen, + * but return appropriate error codes. + * 27-Jan-97 - poe@daimi.aau.dk + * + * Thanks to "two guys named Ian". + * + * $Author: poer $ + * $Revision: 1.13 $ + * $Date: 1997/06/23 08:26:29 $ + */ + +#undef DEBUG + +#include <errno.h> +#include <fcntl.h> +#include <paths.h> +#include <pwd.h> +#include <shadow.h> +#include <signal.h> +#include <stdbool.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/resource.h> +#include <sys/stat.h> +#include <sys/types.h> +#include <unistd.h> + +#include "c.h" +#include "fileutils.h" +#include "closestream.h" +#include "setpwnam.h" + +static void pw_init(void); + +/* + * setpwnam () -- + * takes a struct passwd in which every field is filled in and valid. + * If the given username exists in the passwd file, the entry is + * replaced with the given entry. + */ +int setpwnam(struct passwd *pwd, const char *prefix) +{ + FILE *fp = NULL, *pwf = NULL; + int save_errno, rc; + uint8_t found = 0; + size_t namelen; + size_t contlen; + size_t buflen = 256; + char *linebuf = NULL; + char *tmpname = NULL; + + pw_init(); + + if ((fp = xfmkstemp(&tmpname, "/etc", prefix)) == NULL) + return -1; + + /* ptmp should be owned by root.root or root.wheel */ + if (fchown(fileno(fp), (uid_t) 0, (gid_t) 0) < 0) + goto fail; + + /* acquire exclusive lock */ + if (lckpwdf() < 0) + goto fail; + pwf = fopen(PASSWD_FILE, "r"); + if (!pwf) + goto fail; + + namelen = strlen(pwd->pw_name); + + linebuf = malloc(buflen); + if (!linebuf) + goto fail; + + /* parse the passwd file */ + /* Do you wonder why I don't use getpwent? Read comments at top of + * file */ + while (fgets(linebuf, buflen, pwf) != NULL) { + contlen = strlen(linebuf); + while (linebuf[contlen - 1] != '\n' && !feof(pwf)) { + char *tmp; + /* Extend input buffer if it failed getting the whole line, + * so now we double the buffer size */ + buflen *= 2; + tmp = realloc(linebuf, buflen); + if (tmp == NULL) + goto fail; + linebuf = tmp; + /* And fill the rest of the buffer */ + if (fgets(&linebuf[contlen], buflen / 2, pwf) == NULL) + break; + contlen = strlen(linebuf); + /* That was a lot of work for nothing. Gimme perl! */ + } + + /* Is this the username we were sent to change? */ + if (!found && linebuf[namelen] == ':' && + !strncmp(linebuf, pwd->pw_name, namelen)) { + /* Yes! So go forth in the name of the Lord and + * change it! */ + if (putpwent(pwd, fp) < 0) + goto fail; + found = 1; + continue; + } + /* Nothing in particular happened, copy input to output */ + fputs(linebuf, fp); + } + + /* xfmkstemp is too restrictive by default for passwd file */ + if (fchmod(fileno(fp), 0644) < 0) + goto fail; + rc = close_stream(fp); + fp = NULL; + if (rc != 0) + goto fail; + + fclose(pwf); /* I don't think I want to know if this failed */ + pwf = NULL; + + if (!found) { + errno = ENOENT; /* give me something better */ + goto fail; + } + + /* we don't care if we can't remove the backup file */ + unlink(PASSWD_FILE ".OLD"); + /* we don't care if we can't create the backup file */ + ignore_result(link(PASSWD_FILE, PASSWD_FILE ".OLD")); + /* we DO care if we can't rename to the passwd file */ + if (rename(tmpname, PASSWD_FILE) < 0) + goto fail; + /* finally: success */ + ulckpwdf(); + free(linebuf); + return 0; + + fail: + save_errno = errno; + ulckpwdf(); + if (fp != NULL) + fclose(fp); + if (tmpname != NULL) + unlink(tmpname); + free(tmpname); + if (pwf != NULL) + fclose(pwf); + free(linebuf); + errno = save_errno; + return -1; +} + +/* Set up the limits so that we're not foiled */ +static void pw_init(void) +{ + struct rlimit rlim; + + /* Unlimited resource limits. */ + rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY; + setrlimit(RLIMIT_CPU, &rlim); + setrlimit(RLIMIT_FSIZE, &rlim); + setrlimit(RLIMIT_STACK, &rlim); + setrlimit(RLIMIT_DATA, &rlim); + setrlimit(RLIMIT_RSS, &rlim); + +#ifndef DEBUG + /* Don't drop core (not really necessary, but GP's). */ + rlim.rlim_cur = rlim.rlim_max = 0; + setrlimit(RLIMIT_CORE, &rlim); +#endif + + /* Turn off signals. */ + signal(SIGALRM, SIG_IGN); + signal(SIGHUP, SIG_IGN); + signal(SIGINT, SIG_IGN); + signal(SIGPIPE, SIG_IGN); + signal(SIGQUIT, SIG_IGN); + signal(SIGTERM, SIG_IGN); + signal(SIGTSTP, SIG_IGN); + signal(SIGTTOU, SIG_IGN); + + /* Create with exact permissions. */ + umask(0); +} |