Albert S
c4072a7e95
While interesitng in theory, there is nothing to be gained here, because we don't really have user input at those early stages. As we are also not a privileged process, those early stage sandboxes in the end are not worth it, since they increase complexity while there is no benefit in practise. So, reduce those 3 stages to a single one (enable()), which we activate after CLI server has launched.
83 line
2.5 KiB
C++
83 line
2.5 KiB
C++
#include <vector>
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#include <initializer_list>
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#include <string.h>
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#include <sched.h>
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#include <unistd.h>
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#include <fstream>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <string.h>
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#include <filesystem>
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#include <sys/mount.h>
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#include <sys/capability.h>
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#include <qssb.h>
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#include "../logger.h"
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#include "../utils.h"
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#include "../random.h"
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#include "sandbox-linux.h"
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/* TODO: make a whitelist approach. So far we simply blacklist
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* obvious systemcalls. To whitelist, we need to analyse our
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* dependencies (http library, sqlite wrapper, sqlite lib etc.) */
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bool SandboxLinux::supported()
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{
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std::fstream stream;
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stream.open("/proc/sys/kernel/unprivileged_userns_clone");
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if(stream.is_open())
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{
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std::string str;
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stream >> str;
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if(str[0] == '0')
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{
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Logger::error() << "Please write '1' to /proc/sys/kernel/unprivileged_userns_clone in order to enable "
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"sandboxing support on this system";
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return false;
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}
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}
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return true;
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}
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bool SandboxLinux::enable(std::vector<std::string> fsPaths)
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{
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std::sort(fsPaths.begin(), fsPaths.end(),
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[](const std::string &a, const std::string &b) { return a.length() < b.length(); });
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struct qssb_policy *policy = qssb_init_policy();
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if(policy == NULL)
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{
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Logger::error() << "Failed to init sandboxing policy (worker) ";
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return false;
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}
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for(unsigned int i = 0; i < fsPaths.size(); i++)
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{
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qssb_append_path_policy(policy, QSSB_FS_ALLOW_READ | QSSB_FS_ALLOW_WRITE, fsPaths[i].c_str());
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}
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policy->drop_caps = 1;
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policy->not_dumpable = 1;
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policy->no_new_privs = 1;
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policy->mount_path_policies_to_chroot = 1;
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/* TODO: as said, a whitelist approach is better. As such, this list is bound to be incomplete in the
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* sense that more could be listed here and some critical ones are probably missing */
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/* TODO: use qssb groups */
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long blacklisted_syscalls[] = {QSSB_SYS(setuid), QSSB_SYS(connect), QSSB_SYS(chroot), QSSB_SYS(pivot_root),
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QSSB_SYS(mount), QSSB_SYS(setns), QSSB_SYS(unshare), QSSB_SYS(ptrace),
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QSSB_SYS(personality), QSSB_SYS(prctl), QSSB_SYS(execveat), QSSB_SYS(execve),
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QSSB_SYS(fork)};
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qssb_append_syscalls_policy(policy, QSSB_SYSCALL_DENY_KILL_PROCESS, blacklisted_syscalls,
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sizeof(blacklisted_syscalls) / sizeof(blacklisted_syscalls[0]));
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qssb_append_syscall_default_policy(policy, QSSB_SYSCALL_ALLOW);
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if(qssb_enable_policy(policy) != 0)
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{
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Logger::error() << "Sandbox: Activation of seccomp blacklist failed!";
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qssb_free_policy(policy);
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return false;
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}
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qssb_free_policy(policy);
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return true;
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}
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