Remove malloc() dependency on pledge() / unveil()

This change also fixes a bug with gettid() being incorrect after fork().
We now implement the ENOENT behavior for getauxval(). The getuid() etc.
system calls are now faster too. Plus issetugid() will work on BSDs.
This commit is contained in:
Justine Tunney 2022-07-24 19:40:32 -07:00
parent c921dc78f0
commit 3d2cf95af1
33 changed files with 270 additions and 100 deletions

View file

@ -0,0 +1,419 @@
/*-*- 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/dce.h"
#include "libc/errno.h"
#include "libc/intrin/kprintf.h"
#include "libc/mem/io.h"
#include "libc/runtime/gc.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/testlib.h"
#include "libc/thread/spawn.h"
#include "libc/x/x.h"
STATIC_YOINK("zip_uri_support");
#define EACCES_OR_ENOENT (IsOpenbsd() ? ENOENT : EACCES)
#define SPAWN(METHOD) \
{ \
int ws, pid; \
ASSERT_NE(-1, (pid = METHOD())); \
if (!pid) {
#define EXITS(rc) \
_Exit(0); \
} \
ASSERT_NE(-1, wait(&ws)); \
ASSERT_TRUE(WIFEXITED(ws)); \
ASSERT_EQ(rc, WEXITSTATUS(ws)); \
}
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;
}
__attribute__((__constructor__)) static void init(void) {
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));
}
int extract(const char *from, const char *to, int mode) {
int fdin, fdout;
if ((fdin = open(from, O_RDONLY)) == -1) return -1;
if ((fdout = creat(to, mode)) == -1) {
close(fdin);
return -1;
}
if (_copyfd(fdin, fdout, -1) == -1) {
close(fdout);
close(fdin);
return -1;
}
return close(fdout) | close(fdin);
}
TEST(unveil, api_differences) {
SPAWN(fork);
ASSERT_SYS(0, 0, stat("/", &st));
ASSERT_SYS(0, 0, unveil(".", "rw"));
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));
ASSERT_SYS(0, 0, 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));
ASSERT_SYS(0, 0, 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));
ASSERT_SYS(0, 0, 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));
ASSERT_SYS(0, 0, 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));
ASSERT_SYS(0, 0, 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 = mmap(0, FRAMESIZE, PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_ANONYMOUS, -1, 0)));
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;
ASSERT_SYS(EPERM, -1, socket(AF_UNIX, SOCK_STREAM, 0));
if (IsLinux()) {
ASSERT_SYS(0, 0, stat("garden/secret.txt", &st));
ASSERT_EQ(5, st.st_size); // wut linux metadata is accessible
}
_Exit(0);
}
ASSERT_NE(-1, wait(&ws));
ASSERT_TRUE(*gotsome);
if (IsOpenbsd()) {
ASSERT_TRUE(WIFSIGNALED(ws));
ASSERT_EQ(SIGABRT, WTERMSIG(ws));
} else {
ASSERT_TRUE(WIFEXITED(ws));
ASSERT_EQ(0, WEXITSTATUS(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);
}