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- /* chsh.c - Change login shell.
- *
- * Copyright 2021 Michael Christensen
- *
- * See http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/chsh.html
- USE_CHSH(NEWTOY(chsh, "s:", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_STAYROOT))
- config CHSH
- bool "chsh"
- default n
- help
- usage: chsh [-s SHELL] [USER]
- Change user's login shell.
- -s Use SHELL instead of prompting
- Non-root users can only change their own shell to one listed in /etc/shells.
- */
- #define FOR_chsh
- #include "toys.h"
- GLOBALS(
- char *s;
- )
- void chsh_main()
- {
- FILE *file;
- char *user, *line, *shell, *encrypted;
- struct passwd *passwd_info;
- struct spwd *shadow_info;
- // Get uid user information, may be discarded later
- if ((user = *toys.optargs)) {
- passwd_info = xgetpwnam(user);
- if (geteuid() && strcmp(passwd_info->pw_name, user))
- error_exit("Permission denied\n");
- } else {
- passwd_info = xgetpwuid(getuid());
- user = passwd_info->pw_name;
- }
- // Get a password, encrypt it, wipe it, and check it
- if (mlock(toybuf, sizeof(toybuf))) perror_exit("mlock");
- if (!(shadow_info = getspnam(passwd_info->pw_name))) perror_exit("getspnam");
- if (read_password(toybuf, sizeof(toybuf), "Password: ")) perror_exit("woaj"); //xexit();
- if (!(encrypted = crypt(toybuf, shadow_info->sp_pwdp))) perror_exit("crypt");
- memset(toybuf, 0, sizeof(toybuf));
- munlock(toybuf, sizeof(toybuf)); // prevents memset from "optimizing" away.
- if (strcmp(encrypted, shadow_info->sp_pwdp)) perror_exit("Bad password");
- // Get new shell (either -s or interactive)
- file = xfopen("/etc/shells", "r");
- if (toys.optflags) shell = TT.s;
- else {
- xprintf("Changing the login shell for %s\n"
- "Enter the new value, or press ENTER for default\n"
- " Login shell [%s]: ", user, passwd_info->pw_shell);
- if (!(shell = xgetline(stdin))) xexit();
- }
- // Verify supplied shell in /etc/shells, or get default shell
- if (strlen(shell))
- while ((line = xgetline(file)) && strcmp(shell, line)) free(line);
- else do line = xgetline(file); while (line && *line != '/');
- if (!line) error_exit("Shell not found in '/etc/shells'");
- // Update /etc/passwd
- passwd_info->pw_shell = line;
- if (-1 == update_password("/etc/passwd", user, NULL)) perror_exit("Failed to remove passwd entry");
- file = xfopen("/etc/passwd", "a");
- if (putpwent(passwd_info, file)) perror_exit("putwent");
- }
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