Userland: Add passwd utility

Meta/build-root-filesystem.sh

@@ -37,6 +37,7 @@ chown $window_uid:$window_gid mnt/etc/WindowServer/WindowServer.ini
 echo "/bin/sh" > mnt/etc/shells
 
 chown 0:$wheel_gid mnt/bin/su
+chown 0:$wheel_gid mnt/bin/passwd
 chown 0:$phys_gid mnt/bin/keymap
 chown 0:$phys_gid mnt/bin/shutdown
 chown 0:$phys_gid mnt/bin/reboot
@@ -45,6 +46,7 @@ chown 0:0 mnt/res/kernel.map
 chmod 0400 mnt/res/kernel.map
 chmod 0400 mnt/boot/Kernel
 chmod 4750 mnt/bin/su
+chmod 4755 mnt/bin/passwd
 chmod 4755 mnt/bin/ping
 chmod 4750 mnt/bin/reboot
 chmod 4750 mnt/bin/shutdown

Userland/CMakeLists.txt

@@ -29,6 +29,7 @@ target_link_libraries(md LibMarkdown)
 target_link_libraries(notify LibGUI)
 target_link_libraries(open LibDesktop)
 target_link_libraries(pape LibGUI)
+target_link_libraries(passwd LibCrypt)
 target_link_libraries(paste LibGUI)
 target_link_libraries(pro LibProtocol)
 target_link_libraries(test-crypto LibCrypto LibTLS LibLine)

Userland/passwd.cpp

@@ -0,0 +1,145 @@
+/*
+ * Copyright (c) 2020, Peter Elliott <pelliott@ualberta.ca>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/Base64.h>
+#include <AK/StringBuilder.h>
+#include <AK/Types.h>
+#include <LibCore/ArgsParser.h>
+#include <LibCore/File.h>
+#include <LibCore/GetPassword.h>
+#include <pwd.h>
+#include <string.h>
+#include <unistd.h>
+
+static String get_salt()
+{
+    char random_data[12];
+    arc4random_buf(random_data, sizeof(random_data));
+
+    StringBuilder builder;
+    builder.append("$5$");
+    builder.append(encode_base64(ReadonlyBytes(random_data, sizeof(random_data))));
+
+    return builder.build();
+}
+
+static void write_passwd_file(struct passwd* pwd)
+{
+    StringBuilder new_passwd_file;
+
+    setpwent();
+
+    struct passwd* p;
+    while ((p = getpwent())) {
+        if (p->pw_uid == pwd->pw_uid) {
+            p = pwd;
+        }
+
+        new_passwd_file.appendf("%s:%s:%u:%u:%s:%s:%s\n",
+            p->pw_name, p->pw_passwd, p->pw_uid, p->pw_gid, p->pw_gecos, p->pw_dir, p->pw_shell);
+    }
+    endpwent();
+
+    auto file = Core::File::open("/etc/passwd", Core::IODevice::OpenMode::WriteOnly);
+    if (file.is_error()) {
+        fprintf(stderr, "Core::File::open: %s\n", file.error().characters());
+        exit(1);
+    }
+    file.value()->write(new_passwd_file.build());
+}
+
+int main(int argc, char** argv)
+{
+    if (geteuid() != 0) {
+        fprintf(stderr, "Not running as root :^(\n");
+        return 1;
+    }
+
+    if (pledge("stdio wpath rpath cpath tty", nullptr) < 0) {
+        perror("pledge");
+        return 1;
+    }
+
+    if (unveil("/etc/passwd", "rwc") < 0) {
+        perror("unveil");
+        return 1;
+    }
+
+    unveil(nullptr, nullptr);
+
+    bool del = false;
+    bool lock = false;
+    bool unlock = false;
+    const char* username = nullptr;
+
+    auto args_parser = Core::ArgsParser();
+    args_parser.add_option(del, "Delete password", "delete", 'd');
+    args_parser.add_option(lock, "Lock password", "lock", 'l');
+    args_parser.add_option(unlock, "Unlock password", "unlock", 'u');
+    args_parser.add_positional_argument(username, "Username", "username", Core::ArgsParser::Required::No);
+
+    args_parser.parse(argc, argv);
+
+    uid_t current_user = getuid();
+
+    struct passwd pwd;
+    if (username) {
+        pwd = *getpwnam(username);
+        if (current_user != 0 && current_user != pwd.pw_uid) {
+            fprintf(stderr, "You can't modify passwd for %s.\n", username);
+            return 1;
+        }
+    } else {
+        pwd = *getpwuid(current_user);
+    }
+
+    String pw_string;
+    if (del) {
+        pwd.pw_passwd = const_cast<char*>("");
+    } else if (lock) {
+        StringBuilder builder;
+        builder.append('!');
+        builder.append(pwd.pw_passwd);
+        pw_string = builder.build();
+        pwd.pw_passwd = const_cast<char*>(pw_string.characters());
+    } else if (unlock) {
+        if (pwd.pw_passwd[0] == '!') {
+            pwd.pw_passwd += 1;
+        }
+    } else {
+        auto new_password = Core::get_password("New password: ");
+        if (new_password.is_error()) {
+            fprintf(stderr, strerror(new_password.error()));
+            return 1;
+        }
+
+        pwd.pw_passwd = crypt(new_password.value().characters(), get_salt().characters());
+    }
+
+    write_passwd_file(&pwd);
+
+    return 0;
+}