cosmopolitan/test/libc/calls/unveil_test.c
Gavin Hayes 9c5a7795ad
vista: backport execve escaping and using cocmd as shell for system, etc. (#660)
* Introduce testlib_extract() helper

* Have execve() escape double quotes in cmd.exe's preferred style

This makes it possible for us to use system() and popen() with paths
that redirect to filenames that contain spaces, e.g.

    system("echo.com hello >\"hello there.txt\"")

It's difficult to solve this problem, because WIN32 only allows passing
one single argument when launching programs and each program is allowed
to tokenize that however it wants. Most software follows the convention
of cmd.exe which is poorly documented and positively byzantine.

In the future we're going to solve this by not using cmd.exe at all and
instead embedding the cocmd.com interpreter into the system() function.
In the meantime, our documentation has been updated to help recalibrate
any expectation the user might hold regarding the security of using the
Windows command interpreter.

Fixes #644

* Introduce double quote support in cocmd.com shell

* Add some tests for execve()

* Embed cocmd.com interpreter for system() / open()

This change lets you use system() in an easier and portable way. The
problem with the call in the past has always been that bourne and
cmd.com on Windows have less than nothing in common, so pretty much the
only command system() could be used for across platforms was maybe echo.
cmd.exe is also a security liability due to its escaping rules.

Since cocmd.com implements 85% of what we need from bourne, in a really
tiny way, it makes perfect sense to be embedded in these functionss. We
get a huge performance boost too.

Fixes #644

* Support whitespace after cocmd output redirection

Co-authored-by: Justine Tunney <jtunney@gmail.com>
2022-10-11 21:17:50 -07:00

382 lines
13 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2022 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/calls/landlock.h"
#include "libc/calls/struct/dirent.h"
#include "libc/calls/struct/stat.h"
#include "libc/calls/syscall-sysv.internal.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/intrin/kprintf.h"
#include "libc/mem/io.h"
#include "libc/runtime/gc.h"
#include "libc/runtime/internal.h"
#include "libc/runtime/runtime.h"
#include "libc/sock/sock.h"
#include "libc/stdio/stdio.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/af.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/consts/msync.h"
#include "libc/sysv/consts/o.h"
#include "libc/sysv/consts/prot.h"
#include "libc/sysv/consts/s.h"
#include "libc/sysv/consts/sig.h"
#include "libc/sysv/consts/sock.h"
#include "libc/testlib/subprocess.h"
#include "libc/testlib/testlib.h"
#include "libc/thread/spawn.h"
#include "libc/x/x.h"
#define EACCES_OR_ENOENT (IsOpenbsd() ? ENOENT : EACCES)
char testlib_enable_tmp_setup_teardown;
struct stat st;
static bool SupportsLandlock(void) {
int e = errno;
bool r = landlock_create_ruleset(0, 0, LANDLOCK_CREATE_RULESET_VERSION) >= 0;
errno = e;
return r;
}
void SetUpOnce(void) {
__enable_threads();
if (!(IsLinux() && SupportsLandlock()) && !IsOpenbsd()) exit(0);
}
void SetUp(void) {
// make sure zipos maps executable into memory early
ASSERT_SYS(0, 0, stat("/zip/life.elf", &st));
}
TEST(unveil, api_differences) {
SPAWN(fork);
ASSERT_SYS(0, 0, mkdir("foo", 0755));
ASSERT_SYS(0, 0, unveil("foo", "r"));
if (IsOpenbsd()) {
// openbsd imposes restrictions immediately
ASSERT_SYS(ENOENT, -1, open("/", O_RDONLY | O_DIRECTORY));
} else {
// restrictions on linux don't go into effect until unveil(0,0)
ASSERT_SYS(0, 3, open(".", O_RDONLY | O_DIRECTORY));
ASSERT_SYS(0, 0, close(3));
}
ASSERT_SYS(0, 0, unveil(0, 0));
// error numbers are inconsistent
ASSERT_SYS(EACCES_OR_ENOENT, -1, open("/", O_RDONLY | O_DIRECTORY));
// wut
if (IsLinux()) {
ASSERT_SYS(0, 3, open("/", O_PATH)); // wut
ASSERT_SYS(0, 0, stat("/", &st)); // wut
}
EXITS(0);
}
TEST(unveil, rx_readOnlyPreexistingExecutable_worksFine) {
SPAWN(fork);
ASSERT_SYS(0, 0, mkdir("folder", 0755));
testlib_extract("/zip/life.elf", "folder/life.elf", 0755);
ASSERT_SYS(0, 0, unveil("folder", "rx"));
ASSERT_SYS(0, 0, unveil(0, 0));
SPAWN(fork);
execl("folder/life.elf", "folder/life.elf", 0);
kprintf("execve failed! %s\n", strerror(errno));
_Exit(127);
EXITS(42);
EXITS(0);
}
TEST(unveil, r_noExecutePreexistingExecutable_raisesEacces) {
SPAWN(fork);
ASSERT_SYS(0, 0, mkdir("folder", 0755));
testlib_extract("/zip/life.elf", "folder/life.elf", 0755);
ASSERT_SYS(0, 0, unveil("folder", "r"));
ASSERT_SYS(0, 0, unveil(0, 0));
SPAWN(fork);
ASSERT_SYS(EACCES, -1, execl("folder/life.elf", "folder/life.elf", 0));
EXITS(0);
EXITS(0);
}
TEST(unveil, canBeUsedAgainAfterVfork) {
ASSERT_SYS(0, 0, touch("bad", 0644));
ASSERT_SYS(0, 0, touch("good", 0644));
SPAWN(fork);
SPAWN(vfork);
ASSERT_SYS(0, 0, unveil("bad", "r"));
ASSERT_SYS(0, 0, unveil("good", "r"));
ASSERT_SYS(0, 0, unveil(0, 0));
ASSERT_SYS(0, 3, open("bad", 0));
EXITS(0);
ASSERT_SYS(0, 0, unveil("good", "r"));
ASSERT_SYS(0, 0, unveil(0, 0));
ASSERT_SYS(0, 3, open("good", 0));
ASSERT_SYS(EACCES_OR_ENOENT, -1, open("bad", 0));
EXITS(0);
}
TEST(unveil, rwc_createExecutableFile_isAllowedButCantBeRun) {
SPAWN(fork);
ASSERT_SYS(0, 0, mkdir("folder", 0755));
ASSERT_SYS(0, 0, unveil("folder", "rwc"));
ASSERT_SYS(0, 0, unveil(0, 0));
testlib_extract("/zip/life.elf", "folder/life.elf", 0755);
SPAWN(fork);
ASSERT_SYS(0, 0, stat("folder/life.elf", &st));
ASSERT_SYS(EACCES, -1, execl("folder/life.elf", "folder/life.elf", 0));
EXITS(0);
EXITS(0);
}
TEST(unveil, rwcx_createExecutableFile_canAlsoBeRun) {
SPAWN(fork);
ASSERT_SYS(0, 0, mkdir("folder", 0755));
ASSERT_SYS(0, 0, unveil("folder", "rwcx"));
ASSERT_SYS(0, 0, unveil(0, 0));
testlib_extract("/zip/life.elf", "folder/life.elf", 0755);
SPAWN(fork);
ASSERT_SYS(0, 0, stat("folder/life.elf", &st));
execl("folder/life.elf", "folder/life.elf", 0);
kprintf("execve failed! %s\n", strerror(errno));
_Exit(127);
EXITS(42);
EXITS(0);
}
TEST(unveil, dirfdHacking_doesntWork) {
SPAWN(fork);
ASSERT_SYS(0, 0, mkdir("jail", 0755));
ASSERT_SYS(0, 0, mkdir("garden", 0755));
ASSERT_SYS(0, 0, touch("garden/secret.txt", 0644));
ASSERT_SYS(0, 3, open("garden", O_RDONLY | O_DIRECTORY));
ASSERT_SYS(0, 0, unveil("jail", "rw"));
ASSERT_SYS(0, 0, unveil(0, 0));
ASSERT_SYS(EACCES_OR_ENOENT, -1, openat(3, "secret.txt", O_RDONLY));
EXITS(0);
}
TEST(unveil, mostRestrictivePolicy) {
if (IsOpenbsd()) return; // openbsd behaves oddly; see docs
SPAWN(fork);
ASSERT_SYS(0, 0, mkdir("jail", 0755));
ASSERT_SYS(0, 0, mkdir("garden", 0755));
ASSERT_SYS(0, 0, touch("garden/secret.txt", 0644));
ASSERT_SYS(0, 0, unveil(0, 0));
ASSERT_SYS(EACCES_OR_ENOENT, -1, open("jail", O_RDONLY | O_DIRECTORY));
ASSERT_SYS(EACCES_OR_ENOENT, -1, open("garden/secret.txt", O_RDONLY));
EXITS(0);
}
TEST(unveil, overlappingDirectories_inconsistentBehavior) {
SPAWN(fork);
ASSERT_SYS(0, 0, makedirs("f1/f2", 0755));
testlib_extract("/zip/life.elf", "f1/f2/life.elf", 0755);
ASSERT_SYS(0, 0, unveil("f1", "x"));
ASSERT_SYS(0, 0, unveil("f1/f2", "r"));
ASSERT_SYS(0, 0, unveil(0, 0));
if (IsOpenbsd()) {
// OpenBSD favors the most restrictive policy
SPAWN(fork);
ASSERT_SYS(0, 0, stat("f1/f2/life.elf", &st));
ASSERT_SYS(EACCES, -1, execl("f1/f2/life.elf", "f1/f2/life.elf", 0));
EXITS(0);
} else {
// Landlock (Linux) uses the union of policies
//
// TODO(jart): this test flakes on github actions. it reports an
// exit code of 0! find out why this is happening...
// so far it's happened to MODE=rel and MODE=tiny...
//
// SPAWN(fork);
// ASSERT_SYS(0, 0, stat("f1/f2/life.elf", &st));
// execl("f1/f2/life.elf", "f1/f2/life.elf", 0);
// kprintf("execve failed! %s\n", strerror(errno));
// _Exit(127);
// EXITS(42);
}
EXITS(0);
}
TEST(unveil, usedTwice_allowedOnLinux) {
if (IsOpenbsd()) return;
SPAWN(fork);
ASSERT_SYS(0, 0, mkdir("jail", 0755));
ASSERT_SYS(0, 0, xbarf("jail/ok.txt", "hello", 5));
ASSERT_SYS(0, 0, mkdir("garden", 0755));
ASSERT_SYS(0, 0, xbarf("garden/secret.txt", "hello", 5));
ASSERT_SYS(0, 0, mkdir("heaven", 0755));
ASSERT_SYS(0, 0, xbarf("heaven/verysecret.txt", "hello", 5));
ASSERT_SYS(0, 0, unveil("jail", "rw"));
ASSERT_SYS(0, 0, unveil("garden", "rw"));
ASSERT_SYS(0, 0, unveil(0, 0));
ASSERT_SYS(0, 3, open("garden/secret.txt", O_RDONLY));
ASSERT_SYS(0, 0, unveil("jail", "rw"));
ASSERT_SYS(0, 0, unveil("heaven", "rw")); // not allowed, superset of parent
ASSERT_SYS(0, 0, unveil(0, 0));
ASSERT_SYS(0, 4, open("jail/ok.txt", O_RDONLY));
ASSERT_SYS(EACCES, -1, open("garden/secret.txt", O_RDONLY));
ASSERT_SYS(EACCES, -1, open("heaven/verysecret.txt", O_RDONLY));
EXITS(0);
}
TEST(unveil, truncate_isForbiddenBySeccomp) {
SPAWN(fork);
ASSERT_SYS(0, 0, mkdir("jail", 0755));
ASSERT_SYS(0, 0, mkdir("garden", 0755));
ASSERT_SYS(0, 0, xbarf("garden/secret.txt", "hello", 5));
ASSERT_SYS(0, 0, unveil("jail", "rw"));
ASSERT_SYS(0, 0, unveil(0, 0));
ASSERT_SYS(IsOpenbsd() ? ENOENT : EPERM, -1,
truncate("garden/secret.txt", 0));
if (IsLinux()) {
ASSERT_SYS(0, 0, stat("garden/secret.txt", &st));
ASSERT_EQ(5, st.st_size);
}
EXITS(0);
}
TEST(unveil, ftruncate_isForbidden) {
if (IsOpenbsd()) return; // b/c O_PATH is a Linux thing
SPAWN(fork);
ASSERT_SYS(0, 0, mkdir("jail", 0755));
ASSERT_SYS(0, 0, mkdir("garden", 0755));
ASSERT_SYS(0, 0, xbarf("garden/secret.txt", "hello", 5));
ASSERT_SYS(0, 0, unveil("jail", "rw"));
ASSERT_SYS(0, 0, unveil(0, 0));
ASSERT_SYS(0, 3, open("garden/secret.txt", O_PATH));
ASSERT_SYS(EBADF, -1, ftruncate(3, 0));
ASSERT_SYS(0, 0, close(3));
ASSERT_SYS(0, 0, stat("garden/secret.txt", &st));
ASSERT_EQ(5, st.st_size);
EXITS(0);
}
TEST(unveil, procfs_isForbiddenByDefault) {
if (IsOpenbsd()) return;
SPAWN(fork);
ASSERT_SYS(0, 0, mkdir("jail", 0755));
ASSERT_SYS(0, 0, unveil("jail", "rw"));
ASSERT_SYS(0, 0, unveil(0, 0));
ASSERT_SYS(EACCES, -1, open("/proc/self/cmdline", O_RDONLY));
EXITS(0);
}
int Worker(void *arg, int tid) {
ASSERT_SYS(EACCES_OR_ENOENT, -1, open("garden/secret.txt", O_RDONLY));
return 0;
}
TEST(unveil, isInheritedAcrossThreads) {
struct spawn t;
SPAWN(fork);
ASSERT_SYS(0, 0, mkdir("jail", 0755));
ASSERT_SYS(0, 0, mkdir("garden", 0755));
ASSERT_SYS(0, 0, xbarf("garden/secret.txt", "hello", 5));
ASSERT_SYS(0, 0, unveil("jail", "rw"));
ASSERT_SYS(0, 0, unveil(0, 0));
ASSERT_SYS(0, 0, _spawn(Worker, 0, &t));
EXPECT_SYS(0, 0, _join(&t));
EXITS(0);
}
int Worker2(void *arg, int tid) {
ASSERT_SYS(0, 0, unveil("jail", "rw"));
ASSERT_SYS(0, 0, unveil(0, 0));
ASSERT_SYS(EACCES_OR_ENOENT, -1, open("garden/secret.txt", O_RDONLY));
return 0;
}
TEST(unveil, isThreadSpecificOnLinux_isProcessWideOnOpenbsd) {
struct spawn t;
SPAWN(fork);
ASSERT_SYS(0, 0, mkdir("jail", 0755));
ASSERT_SYS(0, 0, mkdir("garden", 0755));
ASSERT_SYS(0, 0, xbarf("garden/secret.txt", "hello", 5));
ASSERT_SYS(0, 0, _spawn(Worker2, 0, &t));
EXPECT_SYS(0, 0, _join(&t));
if (IsOpenbsd()) {
ASSERT_SYS(ENOENT, -1, open("garden/secret.txt", O_RDONLY));
} else {
ASSERT_SYS(0, 3, open("garden/secret.txt", O_RDONLY));
}
EXITS(0);
}
TEST(unveil, usedTwice_forbidden_worksWithPledge) {
int ws, pid;
bool *gotsome;
ASSERT_NE(-1, (gotsome = _mapshared(FRAMESIZE)));
ASSERT_NE(-1, (pid = fork()));
if (!pid) {
// install our first seccomp filter
ASSERT_SYS(0, 0, pledge("stdio rpath wpath cpath unveil", 0));
ASSERT_SYS(0, 0, mkdir("jail", 0755));
ASSERT_SYS(0, 0, mkdir("garden", 0755));
ASSERT_SYS(0, 0, xbarf("garden/secret.txt", "hello", 5));
ASSERT_SYS(0, 0, unveil("jail", "rw"));
// committing and locking causes a new bpf filter to be installed
ASSERT_SYS(0, 0, unveil(0, 0));
ASSERT_SYS(EACCES_OR_ENOENT, -1, open("garden/secret.txt", O_RDONLY));
// verify the second filter is working
ASSERT_SYS(EACCES_OR_ENOENT, -1, open("garden/secret.txt", O_RDONLY));
// verify the first filter is still working
*gotsome = true;
socket(AF_UNIX, SOCK_STREAM, 0);
_Exit(0);
}
ASSERT_NE(-1, wait(&ws));
ASSERT_TRUE(*gotsome);
ASSERT_TRUE(WIFSIGNALED(ws));
ASSERT_EQ(IsOpenbsd() ? SIGABRT : SIGSYS, WTERMSIG(ws));
EXPECT_SYS(0, 0, munmap(gotsome, FRAMESIZE));
}
TEST(unveil, lotsOfPaths) {
int i, n;
SPAWN(fork);
n = 100;
for (i = 0; i < n; ++i) {
ASSERT_SYS(0, 0, touch(xasprintf("%d", i), 0644));
ASSERT_SYS(0, 0, touch(xasprintf("%d-", i), 0644));
}
for (i = 0; i < n; ++i) {
ASSERT_SYS(0, 0, unveil(xasprintf("%d", i), "rw"));
}
ASSERT_SYS(0, 0, unveil(0, 0));
for (i = 0; i < n; ++i) {
ASSERT_SYS(0, 3, open(xasprintf("%d", i), O_RDONLY));
ASSERT_SYS(0, 0, close(3));
ASSERT_SYS(EACCES_OR_ENOENT, -1, open(xasprintf("%d-", i), O_RDONLY));
}
EXITS(0);
}
TEST(unveil, reparent) {
return; // need abi 2 :'(
SPAWN(fork);
ASSERT_SYS(0, 0, mkdir("x", 0755));
ASSERT_SYS(0, 0, unveil("x", "rwc"));
ASSERT_SYS(0, 0, unveil(0, 0));
ASSERT_SYS(0, 0, mkdir("x/y", 0755));
ASSERT_SYS(0, 0, touch("x/y/z", 0644));
ASSERT_SYS(0, 0, rename("x/y/z", "x/z"));
EXITS(0);
}