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https://github.com/OpenFusionProject/OpenFusion.git
synced 2024-11-24 14:01:05 +00:00
[sandbox] Landlock support
* Support disabling Landlock at compile time or runtime if unsupported, without disabling seccomp * Support older Landlock ABI versions * Support an extra arbitrary RW path, inteded for the coredump dir * Support database locations other than the working directory
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68b56e7c25
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@ -49,6 +49,7 @@ CNShardServer *shardServer = nullptr;
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std::thread *shardThread = nullptr;
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void startShard(CNShardServer* server) {
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sandbox_thread_start();
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server->start();
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}
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@ -150,6 +151,8 @@ int main() {
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/* not reached */
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}
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sandbox_init();
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std::cout << "[INFO] Starting Server Threads..." << std::endl;
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CNLoginServer loginServer(settings::LOGINPORT);
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shardServer = new CNShardServer(settings::SHARDPORT);
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@ -157,6 +160,7 @@ int main() {
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shardThread = new std::thread(startShard, (CNShardServer*)shardServer);
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sandbox_start();
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sandbox_thread_start();
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loginServer.start();
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@ -4,11 +4,16 @@
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#if defined(__linux__) || defined(__OpenBSD__)
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# if !defined(CONFIG_NOSANDBOX)
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void sandbox_init();
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void sandbox_start();
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void sandbox_thread_start();
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# else
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#include <iostream>
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inline void sandbox_init() {}
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inline void sandbox_thread_start() {}
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inline void sandbox_start() {
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std::cout << "[WARN] Built without a sandbox" << std::endl;
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}
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@ -17,5 +22,7 @@ inline void sandbox_start() {
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#else
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// stub for unsupported platforms
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inline void sandbox_init() {}
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inline void sandbox_start() {}
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inline void sandbox_thread_start() {}
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#endif
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@ -13,6 +13,9 @@ static void eunveil(const char *path, const char *permissions) {
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err(1, "unveil");
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}
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void sandbox_init() {}
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void sandbox_thread_start() {}
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void sandbox_start() {
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/*
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* There shouldn't ever be a reason to disable this one, but might as well
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@ -4,6 +4,9 @@
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#include "settings.hpp"
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#include <stdlib.h>
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#include <fcntl.h>
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#include <filesystem>
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#include <sys/prctl.h>
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#include <sys/ptrace.h>
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@ -17,6 +20,10 @@
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#include <linux/audit.h>
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#include <linux/net.h> // for socketcall() args
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#ifndef CONFIG_NOLANDLOCK
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#include <linux/landlock.h>
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#endif
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/*
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* Macros adapted from https://outflux.net/teach-seccomp/
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* Relevant license:
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@ -297,25 +304,178 @@ static sock_fprog prog = {
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ARRLEN(filter), filter
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};
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// our own wrapper for the seccomp() syscall
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// Our own wrapper for the seccomp() syscall.
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int seccomp(unsigned int operation, unsigned int flags, void *args) {
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return syscall(__NR_seccomp, operation, flags, args);
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}
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void sandbox_start() {
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#ifndef CONFIG_NOLANDLOCK
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// Support compilation on systems that only have older Landlock headers.
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#ifndef LANDLOCK_ACCESS_FS_REFER
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#define LANDLOCK_ACCESS_FS_REFER 0
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#endif
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#ifndef LANDLOCK_ACCESS_FS_TRUNCATE
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#define LANDLOCK_ACCESS_FS_TRUNCATE 0
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#endif
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struct landlock_ruleset_attr ruleset_attr = {
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.handled_access_fs = LANDLOCK_ACCESS_FS_READ_FILE
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| LANDLOCK_ACCESS_FS_WRITE_FILE
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| LANDLOCK_ACCESS_FS_READ_DIR
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| LANDLOCK_ACCESS_FS_MAKE_REG
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| LANDLOCK_ACCESS_FS_MAKE_DIR
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| LANDLOCK_ACCESS_FS_MAKE_SYM
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| LANDLOCK_ACCESS_FS_MAKE_SOCK
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| LANDLOCK_ACCESS_FS_MAKE_FIFO
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| LANDLOCK_ACCESS_FS_MAKE_BLOCK
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| LANDLOCK_ACCESS_FS_REMOVE_FILE
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| LANDLOCK_ACCESS_FS_REMOVE_DIR
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| LANDLOCK_ACCESS_FS_TRUNCATE
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| LANDLOCK_ACCESS_FS_REFER
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};
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uint64_t landlock_perms = LANDLOCK_ACCESS_FS_READ_FILE
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| LANDLOCK_ACCESS_FS_WRITE_FILE
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| LANDLOCK_ACCESS_FS_TRUNCATE
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| LANDLOCK_ACCESS_FS_MAKE_REG
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| LANDLOCK_ACCESS_FS_REMOVE_FILE;
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int landlock_fd;
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bool landlock_supported;
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/*
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* Our own wrappers for Landlock syscalls.
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*/
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int landlock_create_ruleset(const struct landlock_ruleset_attr *attr, size_t size, uint32_t flags) {
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return syscall(__NR_landlock_create_ruleset, attr, size, flags);
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}
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int landlock_add_rule(int ruleset_fd, enum landlock_rule_type rule_type, const void *rule_attr, uint32_t flags) {
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return syscall(__NR_landlock_add_rule, ruleset_fd, rule_type, rule_attr, flags);
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}
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int landlock_restrict_self(int ruleset_fd, uint32_t flags) {
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return syscall(__NR_landlock_restrict_self, ruleset_fd, flags);
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}
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static void landlock_path(std::string path, uint32_t perms) {
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struct landlock_path_beneath_attr path_beneath = {
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.allowed_access = perms
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};
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path_beneath.parent_fd = open(path.c_str(), O_PATH|O_CLOEXEC);
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if (path_beneath.parent_fd < 0) {
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perror(path.c_str());
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exit(1);
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}
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if (landlock_add_rule(landlock_fd, LANDLOCK_RULE_PATH_BENEATH, &path_beneath, 0)) {
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perror("landlock_add_rule");
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exit(1);
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}
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close(path_beneath.parent_fd);
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}
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static bool landlock_detect() {
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int abi = landlock_create_ruleset(NULL, 0, LANDLOCK_CREATE_RULESET_VERSION);
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if (abi < 0) {
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if (errno == ENOSYS || errno == EOPNOTSUPP) {
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std::cout << "[WARN] No Landlock support on this system" << std::endl;
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return false;
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}
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perror("landlock_create_ruleset");
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exit(1);
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}
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std::cout << "[INFO] Detected Landlock ABI version: " << abi << std::endl;
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switch (abi) {
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case 1:
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ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_REFER;
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landlock_perms &= ~LANDLOCK_ACCESS_FS_REFER;
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// fallthrough
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case 2:
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ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_TRUNCATE;
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landlock_perms &= ~LANDLOCK_ACCESS_FS_TRUNCATE;
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}
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return true;
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}
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static void landlock_init() {
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std::cout << "[INFO] Setting up Landlock sandbox..." << std::endl;
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landlock_supported = landlock_detect();
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if (!landlock_supported)
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return;
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landlock_fd = landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
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if (landlock_fd < 0) {
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perror("landlock_create_ruleset");
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exit(1);
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}
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std::string dbdir = std::filesystem::path(settings::DBPATH).parent_path();
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// for the DB files (we can't rely on them being in the working directory)
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landlock_path(dbdir == "" ? "." : dbdir, landlock_perms);
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// for writing the gruntwork file
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landlock_path(settings::TDATADIR, landlock_perms);
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// for passowrd salting during account creation
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landlock_path("/dev/urandom", LANDLOCK_ACCESS_FS_READ_FILE);
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// for core dumps, optionally
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if (settings::SANDBOXEXTRAPATH != "")
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landlock_path(settings::SANDBOXEXTRAPATH, landlock_perms);
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}
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#endif // !CONFIG_NOLANDLOCK
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void sandbox_init() {
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if (!settings::SANDBOX) {
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std::cout << "[WARN] Running without a sandbox" << std::endl;
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return;
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}
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#ifndef CONFIG_NOLANDLOCK
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landlock_init();
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#else
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std::cout << "[WARN] Built without Landlock" << std::endl;
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#endif
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}
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void sandbox_start() {
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if (!settings::SANDBOX)
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return;
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std::cout << "[INFO] Starting seccomp-bpf sandbox..." << std::endl;
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// Sandboxing starts in sandbox_thread_start().
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}
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void sandbox_thread_start() {
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if (!settings::SANDBOX)
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return;
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if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) < 0) {
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perror("prctl");
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exit(1);
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}
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if (seccomp(SECCOMP_SET_MODE_FILTER, SECCOMP_FILTER_FLAG_TSYNC, &prog) < 0) {
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#ifndef CONFIG_NOLANDLOCK
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if (landlock_supported) {
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if (landlock_restrict_self(landlock_fd, 0)) {
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perror("landlock_restrict_self");
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exit(1);
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}
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}
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#endif
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if (seccomp(SECCOMP_SET_MODE_FILTER, 0, &prog) < 0) {
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perror("seccomp");
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exit(1);
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}
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@ -9,6 +9,7 @@
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// defaults :)
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int settings::VERBOSITY = 1;
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bool settings::SANDBOX = true;
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std::string settings::SANDBOXEXTRAPATH = "";
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int settings::LOGINPORT = 23000;
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bool settings::APPROVEALLNAMES = true;
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@ -85,6 +86,7 @@ void settings::init() {
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VERBOSITY = reader.GetInteger("", "verbosity", VERBOSITY);
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SANDBOX = reader.GetBoolean("", "sandbox", SANDBOX);
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SANDBOXEXTRAPATH = reader.Get("", "sandboxextrapath", SANDBOXEXTRAPATH);
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LOGINPORT = reader.GetInteger("login", "port", LOGINPORT);
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APPROVEALLNAMES = reader.GetBoolean("login", "acceptallcustomnames", APPROVEALLNAMES);
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AUTOCREATEACCOUNTS = reader.GetBoolean("login", "autocreateaccounts", AUTOCREATEACCOUNTS);
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@ -5,6 +5,7 @@
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namespace settings {
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extern int VERBOSITY;
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extern bool SANDBOX;
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extern std::string SANDBOXEXTRAPATH;
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extern int LOGINPORT;
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extern bool APPROVEALLNAMES;
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extern bool AUTOCREATEACCOUNTS;
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