143 lines
3.1 KiB
C++
143 lines
3.1 KiB
C++
#include <os/ArgumentParser.h>
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#include <pwd.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <termios.h>
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#include <unistd.h>
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static struct termios orig;
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void restore_terminal()
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{
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tcsetattr(STDIN_FILENO, TCSANOW, &orig);
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}
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void signal_handler(int signo)
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{
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restore_terminal();
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raise(signo);
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}
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char* getpass()
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{
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if (!isatty(STDIN_FILENO))
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{
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// FIXME: Just read from /dev/tty (the controlling terminal). Problem: that doesn't exist yet.
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fprintf(stderr, "error: password must be read from a terminal!");
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return nullptr;
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}
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tcsetpgrp(STDIN_FILENO, getpgid(0));
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fputs("Password: ", stdout);
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if (tcgetattr(STDIN_FILENO, &orig) < 0)
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{
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perror("tcgetattr");
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return nullptr;
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}
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struct sigaction sa;
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sa.sa_handler = signal_handler;
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sigemptyset(&sa.sa_mask);
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sa.sa_flags = SA_RESETHAND;
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sigaction(SIGINT, &sa, NULL);
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sigaction(SIGTERM, &sa, NULL);
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sigaction(SIGQUIT, &sa, NULL);
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atexit(restore_terminal);
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struct termios tc = orig;
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tc.c_lflag &= ~ECHO;
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if (tcsetattr(STDIN_FILENO, TCSANOW, &tc) < 0)
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{
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perror("tcsetattr");
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return nullptr;
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}
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static char buf[BUFSIZ];
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char* rc = fgets(buf, sizeof(buf), stdin);
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restore_terminal();
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putchar('\n');
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if (!rc)
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{
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perror("fgets");
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return nullptr;
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}
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char* newline = strrchr(rc, '\n');
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if (newline) *newline = 0;
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return buf;
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}
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Result<int> luna_main(int argc, char** argv)
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{
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StringView name;
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bool prompt_password;
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bool login;
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if (geteuid() != 0)
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{
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fprintf(stderr, "%s must be setuid root!\n", argv[0]);
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return 1;
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}
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os::ArgumentParser parser;
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parser.add_description("Switch to a different user (by default, root)."_sv);
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parser.add_system_program_info("su"_sv);
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parser.add_positional_argument(name, "name"_sv, "root"_sv);
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parser.add_switch_argument(prompt_password, 'p', "prompt", "prompt for a password even if running as root");
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parser.add_switch_argument(login, 'l', "login"_sv, "change directory to the user's home and start a login shell");
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parser.parse(argc, argv);
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struct passwd* entry = getpwnam(name.chars());
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if (!entry)
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{
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fprintf(stderr, "%s: user %s not found!\n", argv[0], name.chars());
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return 1;
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}
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endpwent();
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if ((prompt_password || getuid() != geteuid()) && *entry->pw_passwd)
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{
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signal(SIGTTOU, SIG_IGN);
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char* pass = getpass();
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if (!pass) return 1;
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if (strcmp(pass, entry->pw_passwd))
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{
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fprintf(stderr, "%s: wrong password!\n", argv[0]);
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return 1;
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}
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memset(pass, 0, strlen(pass));
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}
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setgid(entry->pw_gid);
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setuid(entry->pw_uid);
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if (login)
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{
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chdir(entry->pw_dir);
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clearenv();
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setenv("PATH", "/bin:/sbin", 1);
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setpgid(0, 0);
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}
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if (login || entry->pw_uid != 0) setenv("USER", entry->pw_name, 1);
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setenv("HOME", entry->pw_dir, 1);
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setenv("SHELL", entry->pw_shell, 1);
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execl(entry->pw_shell, entry->pw_shell, NULL);
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perror("execl");
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return 1;
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}
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