mozilla-central/security/sandbox/test/browser_content_sandbox_syscalls.js (file symbol)

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Test Info: Warnings

/* Any copyright is dedicated to the Public Domain.
/* import-globals-from browser_content_sandbox_utils.js */
"use strict";
Services.scriptloader.loadSubScript(
"security/sandbox/test/browser_content_sandbox_utils.js",
this
);
const lazy = {};
/* getLibcConstants is only present on *nix */
ChromeUtils.defineLazyGetter(lazy, "LIBC", () =>
ChromeUtils.getLibcConstants()
);
/*
* This test is for executing system calls in content processes to validate
* that calls that are meant to be blocked by content sandboxing are blocked.
* We use the term system calls loosely so that any OS API call such as
* fopen could be included.
*/
// Calls the native execv library function. Include imports so this can be
// safely serialized and run remotely by ContentTask.spawn.
function callExec(args) {
const { ctypes } = ChromeUtils.importESModule(
"resource://gre/modules/ctypes.sys.mjs"
);
let { lib, cmd } = args;
let libc = ctypes.open(lib);
let exec = libc.declare(
"execv",
ctypes.default_abi,
ctypes.int,
ctypes.char.ptr
);
let rv = exec(cmd);
libc.close();
return rv;
}
// Calls the native fork syscall.
function callFork(args) {
const { ctypes } = ChromeUtils.importESModule(
"resource://gre/modules/ctypes.sys.mjs"
);
let { lib } = args;
let libc = ctypes.open(lib);
let fork = libc.declare("fork", ctypes.default_abi, ctypes.int);
let rv = fork();
libc.close();
return rv;
}
// Calls the native sysctl syscall.
function callSysctl(args) {
const { ctypes } = ChromeUtils.importESModule(
"resource://gre/modules/ctypes.sys.mjs"
);
let { lib, name } = args;
let libc = ctypes.open(lib);
let sysctlbyname = libc.declare(
"sysctlbyname",
ctypes.default_abi,
ctypes.int,
ctypes.char.ptr,
ctypes.voidptr_t,
ctypes.size_t.ptr,
ctypes.voidptr_t,
ctypes.size_t.ptr
);
let rv = sysctlbyname(name, null, null, null, null);
libc.close();
return rv;
}
function callPrctl(args) {
const { ctypes } = ChromeUtils.importESModule(
"resource://gre/modules/ctypes.sys.mjs"
);
let { lib, option } = args;
let libc = ctypes.open(lib);
let prctl = libc.declare(
"prctl",
ctypes.default_abi,
ctypes.int,
ctypes.int, // option
ctypes.unsigned_long, // arg2
ctypes.unsigned_long, // arg3
ctypes.unsigned_long, // arg4
ctypes.unsigned_long // arg5
);
let rv = prctl(option, 0, 0, 0, 0);
if (rv == -1) {
rv = ctypes.errno;
}
libc.close();
return rv;
}
// Calls the native open/close syscalls.
function callOpen(args) {
const { ctypes } = ChromeUtils.importESModule(
"resource://gre/modules/ctypes.sys.mjs"
);
let { lib, path, flags } = args;
let libc = ctypes.open(lib);
let open = libc.declare(
"open",
ctypes.default_abi,
ctypes.int,
ctypes.char.ptr,
ctypes.int
);
let close = libc.declare("close", ctypes.default_abi, ctypes.int, ctypes.int);
let fd = open(path, flags);
close(fd);
libc.close();
return fd;
}
// Verify faccessat2
function callFaccessat2(args) {
const { ctypes } = ChromeUtils.importESModule(
"resource://gre/modules/ctypes.sys.mjs"
);
let { lib, dirfd, path, mode, flag } = args;
let libc = ctypes.open(lib);
let faccessat = libc.declare(
"faccessat",
ctypes.default_abi,
ctypes.int,
ctypes.int, // dirfd
ctypes.char.ptr, // path
ctypes.int, // mode
ctypes.int // flag
);
let rv = faccessat(dirfd, path, mode, flag);
if (rv == -1) {
rv = ctypes.errno;
}
libc.close();
return rv;
}
// Returns the name of the native library needed for native syscalls
function getOSLib() {
switch (Services.appinfo.OS) {
case "WINNT":
return "kernel32.dll";
case "Darwin":
return "libc.dylib";
case "Linux":
return "libc.so.6";
default:
Assert.ok(false, "Unknown OS");
return 0;
}
}
// Reading a header might be weird, but the alternatives to read a stable
// version number we can easily check against are not much more fun
async function getKernelVersion() {
let header = await IOUtils.readUTF8("/usr/include/linux/version.h");
let hr = header.split("\n");
for (let line in hr) {
let hrs = hr[line].split(" ");
if (hrs[0] === "#define" && hrs[1] === "LINUX_VERSION_CODE") {
return Number(hrs[2]);
}
}
throw Error("No LINUX_VERSION_CODE");
}
// This is how it is done in /usr/include/linux/version.h
function computeKernelVersion(major, minor, dot) {
return (major << 16) + (minor << 8) + dot;
}
function getGlibcVersion() {
const { ctypes } = ChromeUtils.importESModule(
"resource://gre/modules/ctypes.sys.mjs"
);
let libc = ctypes.open(getOSLib());
let gnu_get_libc_version = libc.declare(
"gnu_get_libc_version",
ctypes.default_abi,
ctypes.char.ptr
);
let rv = gnu_get_libc_version().readString();
libc.close();
let ar = rv.split(".");
// return a number made of MAJORMINOR
return Number(ar[0] + ar[1]);
}
// Returns a harmless command to execute with execv
function getOSExecCmd() {
Assert.ok(!isWin());
return "/bin/cat";
}
// Returns true if the current content sandbox level, passed in
// the |level| argument, supports syscall sandboxing.
function areContentSyscallsSandboxed(level) {
let syscallsSandboxMinLevel = 0;
// Set syscallsSandboxMinLevel to the lowest level that has
// syscall sandboxing enabled. For now, this varies across
// Windows, Mac, Linux, other.
switch (Services.appinfo.OS) {
case "WINNT":
syscallsSandboxMinLevel = 1;
break;
case "Darwin":
syscallsSandboxMinLevel = 1;
break;
case "Linux":
syscallsSandboxMinLevel = 1;
break;
default:
Assert.ok(false, "Unknown OS");
}
return level >= syscallsSandboxMinLevel;
}
//
// Drive tests for a single content process.
//
// Tests executing OS API calls in the content process. Limited to Mac
// and Linux calls for now.
//
add_task(async function () {
// This test is only relevant in e10s
if (!gMultiProcessBrowser) {
ok(false, "e10s is enabled");
info("e10s is not enabled, exiting");
return;
}
let level = 0;
let prefExists = true;
// Read the security.sandbox.content.level pref.
// If the pref isn't set and we're running on Linux on !isNightly(),
// exit without failing. The Linux content sandbox is only enabled
// on Nightly at this time.
// eslint-disable-next-line mozilla/use-default-preference-values
try {
level = Services.prefs.getIntPref("security.sandbox.content.level");
} catch (e) {
prefExists = false;
}
ok(prefExists, "pref security.sandbox.content.level exists");
if (!prefExists) {
return;
}
info(`security.sandbox.content.level=${level}`);
Assert.greater(level, 0, "content sandbox is enabled.");
let areSyscallsSandboxed = areContentSyscallsSandboxed(level);
// Content sandbox enabled, but level doesn't include syscall sandboxing.
ok(areSyscallsSandboxed, "content syscall sandboxing is enabled.");
if (!areSyscallsSandboxed) {
info("content sandbox level too low for syscall tests, exiting\n");
return;
}
let browser = gBrowser.selectedBrowser;
let lib = getOSLib();
// use execv syscall
// (causes content process to be killed on Linux)
if (isMac()) {
// exec something harmless, this should fail
let cmd = getOSExecCmd();
let rv = await SpecialPowers.spawn(browser, [{ lib, cmd }], callExec);
Assert.equal(rv, -1, `exec(${cmd}) is not permitted`);
}
// use open syscall
if (isLinux() || isMac()) {
// open a file for writing in $HOME, this should fail
let path = fileInHomeDir().path;
let flags = lazy.LIBC.O_CREAT | lazy.LIBC.O_WRONLY;
let fd = await SpecialPowers.spawn(
browser,
[{ lib, path, flags }],
callOpen
);
Assert.less(fd, 0, "opening a file for writing in home is not permitted");
}
// use open syscall
if (isLinux() || isMac()) {
// open a file for writing in the content temp dir, this should fail on
// macOS and Linux. The open handler in the content process closes the file
// for us
let path = fileInTempDir().path;
let flags = lazy.LIBC.O_CREAT | lazy.LIBC.O_WRONLY;
let fd = await SpecialPowers.spawn(
browser,
[{ lib, path, flags }],
callOpen
);
Assert.strictEqual(
fd,
-1,
"opening a file for writing in content temp is not permitted"
);
}
// use fork syscall
if (isLinux() || isMac()) {
let rv = await SpecialPowers.spawn(browser, [{ lib }], callFork);
Assert.equal(rv, -1, "calling fork is not permitted");
}
// On macOS before 10.10 the |sysctl-name| predicate didn't exist for
// filtering |sysctl| access. Check the Darwin version before running the
// tests (Darwin 14.0.0 is macOS 10.10). This branch can be removed when we
// remove support for macOS 10.9.
if (isMac() && Services.sysinfo.getProperty("version") >= "14.0.0") {
let rv = await SpecialPowers.spawn(
browser,
[{ lib, name: "kern.boottime" }],
callSysctl
);
Assert.equal(rv, -1, "calling sysctl('kern.boottime') is not permitted");
rv = await SpecialPowers.spawn(
browser,
[{ lib, name: "net.inet.ip.ttl" }],
callSysctl
);
Assert.equal(rv, -1, "calling sysctl('net.inet.ip.ttl') is not permitted");
rv = await SpecialPowers.spawn(
browser,
[{ lib, name: "hw.ncpu" }],
callSysctl
);
Assert.equal(rv, 0, "calling sysctl('hw.ncpu') is permitted");
}
if (isLinux()) {
// These constants are not portable.
// verify we block PR_CAPBSET_READ with EINVAL
let option = lazy.LIBC.PR_CAPBSET_READ;
let rv = await SpecialPowers.spawn(browser, [{ lib, option }], callPrctl);
Assert.strictEqual(
rv,
lazy.LIBC.EINVAL,
"prctl(PR_CAPBSET_READ) is blocked"
);
const kernelVersion = await getKernelVersion();
const glibcVersion = getGlibcVersion();
// faccessat2 is only used with kernel 5.8+ by glibc 2.33+
if (glibcVersion >= 233 && kernelVersion >= computeKernelVersion(5, 8, 0)) {
info("Linux v5.8+, glibc 2.33+, checking faccessat2");
const dirfd = 0;
const path = "/";
const mode = 0;
// the value 0x01 is just one we know should get rejected
let rv = await SpecialPowers.spawn(
browser,
[{ lib, dirfd, path, mode, flag: 0x01 }],
callFaccessat2
);
Assert.strictEqual(
rv,
lazy.LIBC.ENOSYS,
"faccessat2 (flag=0x01) was blocked with ENOSYS"
);
rv = await SpecialPowers.spawn(
browser,
[{ lib, dirfd, path, mode, flag: lazy.LIBC.AT_EACCESS }],
callFaccessat2
);
Assert.strictEqual(
rv,
lazy.LIBC.EACCES,
"faccessat2 (flag=0x200) was allowed, errno=EACCES"
);
} else {
info(
"Unsupported kernel (" +
kernelVersion +
" )/glibc (" +
glibcVersion +
"), skipping faccessat2"
);
}
}
});