runuser,drop: drop runuser, tweak drop

Remove the runuser applet, leaving only drop.  Move drop from
util-linux to miscutils.

A command of the form 'drop -c command' causes the BusyBox shell
to be used, just like 'drop' without any arguments.  A simple
OpenSSH configuration with 'drop.exe' as DefaultShell and no
DefaultShellArguments now works both for interactive login and
to run a command.  This is useful for older versions of OpenSSH
which don't support DefaultShellArguments.

Saves 208-232 bytes.

1 files changed, 0 insertions, 164 deletions

diff --git a/util-linux/runuser.c b/util-linux/runuser.c
deleted file mode 100644
index 993a4ed68..000000000
--- a/util-linux/runuser.c
+++ /dev/null
@@ -1,164 +0,0 @@
-/* vi: set sw=4 ts=4: */
-/*
- * runuser - run a shell without elevated privileges.
- * This is a much restricted, Windows-specific reimplementation of
- * runuser from util-linux.
- *
- * Copyright (c) 2023 Ronald M Yorston
- *
- * Licensed under GPLv2 or later, see file LICENSE in this source tree.
- */
-//config:config RUNUSER
-//config:       bool "runuser"
-//config:       default y
-//config:       depends on PLATFORM_MINGW32 && SH_IS_ASH
-//config:       help
-//config:       Run a shell without elevated privileges
-//config:
-//config:config DROP
-//config:       bool "drop"
-//config:       default y
-//config:       depends on PLATFORM_MINGW32 && SH_IS_ASH
-//config:       help
-//config:       Run a command without elevated privileges
-
-//applet:IF_RUNUSER(APPLET(runuser, BB_DIR_USR_BIN, BB_SUID_DROP))
-//applet:IF_DROP(APPLET_ODDNAME(drop, runuser, BB_DIR_USR_BIN, BB_SUID_DROP, drop))
-
-//kbuild:lib-$(CONFIG_RUNUSER) += runuser.o
-//kbuild:lib-$(CONFIG_DROP) += runuser.o
-
-//usage:#define runuser_trivial_usage
-//usage:        "USER [ARG...]"
-//usage:#define runuser_full_usage "\n\n"
-//usage:        "Run a shell without elevated privileges. The user name\n"
-//usage:        "must be that of the user who was granted those privileges.\n"
-//usage:        "Any arguments are passed to the shell.\n"
-
-//usage:#define drop_trivial_usage
-//usage:        "[COMMAND [ARG...]]"
-//usage:#define drop_full_usage "\n\n"
-//usage:        "Run a command without elevated privileges. Run the BusyBox\n"
-//usage:        "shell if no COMMAND is provided. Any arguments are passed\n"
-//usage:        "to the command.\n"
-
-#include "libbb.h"
-#include <winsafer.h>
-#include <lazyload.h>
-
-int runuser_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
-int runuser_main(int argc, char **argv)
-{
-#if ENABLE_RUNUSER && ENABLE_DROP
-        int is_runuser = strcmp(applet_name, "runuser") == 0;
-#else
-        const int is_runuser = ENABLE_RUNUSER;
-#endif
-        const char *user, *exe;
-        SAFER_LEVEL_HANDLE safer;
-        HANDLE token;
-        STARTUPINFO si;
-        PROCESS_INFORMATION pi;
-        TOKEN_MANDATORY_LABEL TIL;
-        // Medium integrity level S-1-16-8192
-        unsigned char medium[12] = {
-                0x01, 0x01, 0x00, 0x00,
-                0x00, 0x00, 0x00, 0x10,
-                0x00, 0x20, 0x00, 0x00
-        };
-        char *cmd, *q, *newcmd, **a;
-        DWORD code;
-        // This shouldn't be necessary but without it the binary complains
-        // it can't find CreateProcessAsUserA on older versions of Windows.
-        DECLARE_PROC_ADDR(BOOL, CreateProcessAsUserA, HANDLE, LPCSTR, LPSTR,
-                        LPSECURITY_ATTRIBUTES, LPSECURITY_ATTRIBUTES, BOOL, DWORD,
-                        LPVOID, LPCSTR, LPSTARTUPINFOA, LPPROCESS_INFORMATION);
-
-        if (!INIT_PROC_ADDR(advapi32.dll, CreateProcessAsUserA))
-                bb_simple_error_msg_and_die("not supported");
-
-        if (is_runuser) {
-                if (getuid() != 0)
-                        bb_simple_error_msg_and_die("may not be used by non-root users");
-
-                if (argc < 2)
-                        bb_show_usage();
-
-                user = get_user_name();
-                if (user == NULL || strcmp(argv[1], user) != 0)
-                        bb_simple_error_msg_and_die("invalid user");
-        }
-
-        /*
-         * Run a shell using a token with reduced privilege.  Hints from:
-         *
-         *    https://stackoverflow.com/questions/17765568/
-         */
-        if (SaferCreateLevel(SAFER_SCOPEID_USER, SAFER_LEVELID_NORMALUSER,
-                                        SAFER_LEVEL_OPEN, &safer, NULL) &&
-                        SaferComputeTokenFromLevel(safer, NULL, &token, 0, NULL)) {
-
-                // Set medium integrity
-                TIL.Label.Sid = (PSID)medium;
-                TIL.Label.Attributes = SE_GROUP_INTEGRITY;
-                if (SetTokenInformation(token, TokenIntegrityLevel, &TIL,
-                                                sizeof(TOKEN_MANDATORY_LABEL))) {
-
-                        if (is_runuser || argc == 1) {
-                                exe = bb_busybox_exec_path;
-                                cmd = xstrdup("sh");
-                        } else {
-                                char *file;
-
-#if ENABLE_FEATURE_PREFER_APPLETS
-                                if (!has_path(argv[1]) && find_applet_by_name(argv[1]) >= 0) {
-                                        file = xstrdup(bb_busybox_exec_path);
-                                } else
-#endif
-                                if (has_path(argv[1])) {
-                                        file = file_is_win32_exe(argv[1]);
-                                } else {
-                                        file = find_first_executable(argv[1]);
-                                }
-
-                                if (file == NULL) {
-                                        xfunc_error_retval = 127;
-                                        bb_error_msg_and_die("can't find '%s'", argv[1]);
-                                }
-
-                                slash_to_bs(file);
-                                exe = file;
-                                cmd = quote_arg(argv[1]);
-                        }
-
-                        // Build the command line
-                        for (a = argv + 1 + (argc != 1); *a; ++a) {
-                                q = quote_arg(*a);
-                                newcmd = xasprintf("%s %s", cmd, q);
-                                free(q);
-                                free(cmd);
-                                cmd = newcmd;
-                        }
-
-                        ZeroMemory(&si, sizeof(STARTUPINFO));
-                        si.cb = sizeof(STARTUPINFO);
-                        si.hStdInput = GetStdHandle(STD_INPUT_HANDLE);
-                        si.hStdOutput = GetStdHandle(STD_OUTPUT_HANDLE);
-                        si.hStdError = GetStdHandle(STD_ERROR_HANDLE);
-                        si.dwFlags = STARTF_USESTDHANDLES;
-
-                        if (!CreateProcessAsUserA(token, exe, cmd, NULL, NULL, TRUE,
-                                                0, NULL, NULL, &si, &pi)) {
-                                xfunc_error_retval = 126;
-                                bb_error_msg_and_die("can't execute '%s'", exe);
-                        }
-
-                        WaitForSingleObject(pi.hProcess, INFINITE);
-                        if (GetExitCodeProcess(pi.hProcess, &code)) {
-                                return (int)code;
-                        }
-                }
-        }
-
-        return EXIT_FAILURE;
-}