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784e3de7cd
passwd, ps, purge, shutdown, stty, upper, and vi. These sources are for the versions of the utils shipped with GNO v2.0.4.
210 lines
5.8 KiB
C
210 lines
5.8 KiB
C
/************************************************************
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**
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** passwd - change user passwords
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**
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** Programmed by: Eric Shepherd
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** Date: September 6, 1993
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**
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** Requires GNO 2.0
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**
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**===========================================================
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** Revision history:
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**
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** 1.0: Updated version numbers to final.
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** 1.0b1: Changed the sleep(1) call to an asm { cop
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** 0x7F };. Also removed the "conflict" error
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** message. Instead, if the call to remove
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** /etc/passwd fails, we sleep and retry until
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** it succeeds, thus eliminating the problem...
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** there's no significant reason why that file
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** will stay open longer than a moment or two.
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** 1.0a4: Now uses getpass(), since it's been fixed.
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** 1.0a3: Adjusted closing code to shrink the window
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** during which the system is vulnerable to
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** becoming unprotected. Also added code to
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** retry renaming passwd.new until it succeeds.
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** 1.0a2: Optimized code, added optimize and stacksize
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** pragmas, added new error message for the
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** off chance that the rename could fail. Code
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** size reduced by about 2K.
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** 1.0a1: Works completely, except that getpass()
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** crashes all the time, so I don't use it.
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** Also, due to apparent login bug, sometimes
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** the /etc/passwd file doesn't get updated --
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** the corrected file is in /etc/passwd.new.
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*************************************************************/
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#pragma optimize -1
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#pragma stacksize 512
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#include <stdio.h>
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#include <string.h>
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#include <gno/gno.h>
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#include <sys/types.h>
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#include <getopt.h>
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#include <pwd.h>
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#include <ctype.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <sys/stat.h>
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extern char *crypt(char *key, char *salt);
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extern char *getpass(char *prompt);
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char entry[129];
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static unsigned char salttab[] = /* table of chars. for salt */
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"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
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void usage(void) {
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fprintf(stderr, "usage: passwd [-v|?] [username]\n");
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}
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void makesalt(char *salt, long seed) {
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int num = 2;
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while (--num >= 0) {
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*salt++ = salttab[seed&0x3f];
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seed >= 6;
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}
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}
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void main(int argc, char **argv) {
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extern int optind;
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int ch, uid, tries;
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char password[9]; /* password string (8+\0) */
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char *p, *t;
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char salt[3];
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FILE *passfile, *newpass; /* file /etc/newpasswd */
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char *uname; /* pointer to username to change passwd of */
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struct passwd *passwdRec;
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while ((ch = getopt(argc, argv, "v?")) != EOF)
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switch (ch) {
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case 'v':
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fprintf(stderr, "GNO passwd v1.0 by Eric Shepherd (September 6, 1993)\n");
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exit(1);
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case '?':
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usage();
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exit(1);
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}
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argc -= optind; /* move to next option */
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argv += optind;
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/* if no username supplied, use the current user's name */
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uid = getuid(); /* get the user's ID */
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switch(argc) {
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case 1:
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uname = argv[0];
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if (!(passwdRec = getpwnam(uname))) {
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fprintf(stderr, "Unknown user %s.\n", uname);
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exit(1);
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}
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/* the following code verifies that the user only tries to
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change his own password, unless he is superuser */
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if (uid && uid != passwdRec->pw_uid) {
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fprintf(stderr, "You can't change other users' passwords.\n");
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exit(1);
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}
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break;
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case 0:
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passwdRec = getpwuid(uid);
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break;
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default:
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usage();
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exit(1);
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}
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uname = passwdRec->pw_name; /* make sure we have the right one */
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/* Here's the code to handle changing passwords */
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printf("Changing password for user %s.\n", uname);
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if (uid && strlen(passwdRec->pw_passwd) &&
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strcmp(crypt(getpass("Old password:"), passwdRec->pw_passwd),
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passwdRec->pw_passwd)) {
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fprintf(stderr,"Password incorrect.\n");
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exit(1);
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}
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for (password[0] = '\0', tries = 0;;) {
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p = getpass("New password:");
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if (!*p) {
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printf("Password unchanged.\n");
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exit(0);
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}
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if (strlen(p) <= 5 && (uid != 0 || ++tries < 2)) {
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printf("Please enter a longer password.\n");
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continue;
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}
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/* Let only root assign easy passwords */
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for (t = p; *t && islower(*t); ++t);
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if (!*t && (uid != 0 || ++tries < 2)) {
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printf("All-lower-case passwords can be easy to break. Please use unusual\ncapitalization, control characters, and digits.\n");
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continue;
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}
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strcpy(password, p); /* snag a copy of the password */
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if (!strcmp(password, getpass("Retype new password:")))
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break; /* ah! got it! */
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printf("That's not what you typed the first time. Please start over, or\nhit CTRL-@ to quit.\n");
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}
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/* create salt randomly after seeding the random number generator */
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srand((int) time((time_t *) NULL));
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makesalt(&salt[0], rand());
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/* Copy /etc/passwd to /etc/passwd.new, line-by-line, skipping
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the entry for the user whose password is changing -- insert
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the new entry instead. */
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if (!(passfile = fopen("/etc/passwd", "r"))) {
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fprintf(stderr, "Unable to open /etc/passwd.\n");
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exit(1);
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}
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if (!(newpass = fopen("/etc/passwd.new", "w"))) {
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fclose(passfile); /* it's already open, so close it -- unlike login :) */
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fprintf(stderr, "Unable to write new /etc/passwd.\n");
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exit(1);
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}
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while (!feof(passfile)) {
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if (strncmp(passwdRec->pw_name, fgets(entry, 129, passfile),
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strlen(passwdRec->pw_name)))
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fputs(entry, newpass); /* not us -- just copy it */
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else
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fprintf(newpass, "%s:%s:%d:%d:%s:%s:%s\n", passwdRec->pw_name,
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crypt(password, salt), passwdRec->pw_uid, passwdRec->pw_gid,
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passwdRec->pw_comment, passwdRec->pw_dir, passwdRec->pw_shell);
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}
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fclose(passfile);
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asm { cop 0x7F }; /* Jawaid sez this is better than sleep(1) */
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/* Erase the old file and rename the new one */
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while (remove("/etc/passwd"))
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sleep(1); /* Keep trying */
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fclose(newpass); /* NOW close the new file */
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/* As long as the rename fails, wait a moment, then try again */
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while (rename("/etc/passwd.new", "/etc/passwd"))
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sleep(1); /* sleep one second before trying again */
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}
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