1 files changed, 150 insertions, 0 deletions
diff --git a/FICS/prep_dir_for_privdrop.cpp b/FICS/prep_dir_for_privdrop.cpp
new file mode 100644
index 0000000..399fdb4
--- /dev/null
+++ b/FICS/prep_dir_for_privdrop.cpp
@@ -0,0 +1,150 @@
+// SPDX-FileCopyrightText: 2025 Markus Uhlin <maxxe@rpblc.net>
+// SPDX-License-Identifier: ISC
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <err.h>
+#include <fcntl.h>
+#include <pwd.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <filesystem>
+#include <string>
+
+#include "addgroup.h"
+#include "prep_dir_for_privdrop.h"
+#include "settings.h"
+#include "utils.h"
+
+namespace fs = std::filesystem;
+
+static int
+get_uid_and_gid(uid_t &uid, gid_t &gid)
+{
+	struct passwd *pw = nullptr;
+	int i = 0;
+
+	if ((pw = getpwnam(settings_get("privdrop_user"))) == nullptr ||
+	    !get_group_id(settings_get("sysgroup"), &i)) {
+		uid = 0;
+		gid = 0;
+		return -1;
+	}
+
+	uid = pw->pw_uid;
+	gid = static_cast<gid_t>(i);
+	return 0;
+}
+
+static int
+check_prep_done(const char *p_path)
+{
+	std::string path(p_path);
+
+	path.append("/").append(".prep_done");
+
+	if (file_exists(path.c_str()))
+		return 0;
+	return -1;
+}
+
+static void
+prep_done(const char *p_path)
+{
+	int		fd;
+	std::string	path(p_path);
+	uid_t		uid = 0;
+	gid_t		gid = 0;
+
+	path.append("/").append(".prep_done");
+
+	fd = open(path.c_str(), (O_RDWR|O_CREAT|O_TRUNC), (S_IRUSR|S_IWUSR|
+	    S_IRGRP|S_IROTH));
+	if (fd < 0) {
+		warn("%s: open", __func__);
+		return;
+	}
+
+	dprintf(fd, "FICS dir preparation done.\n"
+	    "Do not remove this file while FICS is installed.\n");
+	close(fd);
+
+	if (get_uid_and_gid(uid, gid) == 0) {
+		if (chown(path.c_str(), uid, gid) != 0)
+			warn("%s: chown", __func__);
+	}
+}
+
+int
+drop_root_privileges(const char *path)
+{
+	struct passwd *pw;
+
+	if ((pw = getpwnam(settings_get("privdrop_user"))) == nullptr) {
+		warnx("%s: password database search failed", __func__);
+		return -1;
+	} else if (chdir(path) != 0) {
+		warn("%s: chdir(%s)", __func__, path);
+		return -1;
+	} else if (setgid(pw->pw_gid) == -1) {
+		warn("%s: setgid", __func__);
+		return -1;
+	} else if (setegid(pw->pw_gid) == -1) {
+		warn("%s: setegid", __func__);
+		return -1;
+	} else if (setuid(pw->pw_uid) == -1) {
+		warn("%s: setuid", __func__);
+		return -1;
+	} else if (seteuid(pw->pw_uid) == -1) {
+		warn("%s: seteuid", __func__);
+		return -1;
+	}
+
+	return 0;
+}
+
+int
+prep_dir_for_privdrop(const char *path)
+{
+	if (path == nullptr || strcmp(path, "") == 0)
+		return -1;
+	else if (check_prep_done(path) == 0)
+		return 0;
+	try {
+		fs::path		v_path = path;
+		fs::directory_iterator	dir_it(v_path);
+		uid_t			uid = 0;
+		gid_t			gid = 0;
+		constexpr mode_t	dir_mode = (S_IRUSR|S_IWUSR|
+					    S_IRGRP|S_IWGRP|S_IROTH);
+		constexpr mode_t	file_mode = (S_IRUSR|S_IWUSR|S_IRGRP|
+					    S_IROTH);
+
+		if (get_uid_and_gid(uid, gid) == -1)
+			throw std::runtime_error("failed to get uid/gid");
+		for (auto const &dir_ent : dir_it) {
+			const std::string str(dir_ent.path().string());
+			
+			if (chown(str.c_str(), uid, gid) != 0) {
+				warn("%s: chown(%s, ...)", __func__,
+				    str.c_str());
+			}
+
+			if (dir_ent.is_directory()) {
+				if (chmod(str.c_str(), dir_mode) != 0)
+					warn("%s: chmod", __func__);
+			} else if (dir_ent.is_regular_file()) {
+				if (chmod(str.c_str(), file_mode) != 0)
+					warn("%s: chmod", __func__);
+			}
+		}
+	} catch (const std::exception &ex) {
+		warnx("%s: %s", __func__, ex.what());
+		return -1;
+	}
+
+	prep_done(path);
+	return 0;
+}