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// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "sandbox/linux/seccomp-bpf-helpers/syscall_parameters_restrictions.h"
#include <errno.h>
#include <fcntl.h>
#include <linux/net.h>
#include <sched.h>
#include <signal.h>
#include <stdint.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/prctl.h>
#include <sys/ptrace.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
#include "base/allocator/partition_alloc_features.h"
#include "base/feature_list.h"
#include "base/features.h"
#include "base/notreached.h"
#include "base/synchronization/synchronization_buildflags.h"
#include "build/build_config.h"
#include "sandbox/linux/bpf_dsl/bpf_dsl.h"
#include "sandbox/linux/bpf_dsl/seccomp_macros.h"
#include "sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h"
#include "sandbox/linux/seccomp-bpf/sandbox_bpf.h"
#include "sandbox/linux/system_headers/linux_futex.h"
#include "sandbox/linux/system_headers/linux_prctl.h"
#include "sandbox/linux/system_headers/linux_ptrace.h"
#include "sandbox/linux/system_headers/linux_syscalls.h"
#include "sandbox/linux/system_headers/linux_time.h"
#if BUILDFLAG(IS_LINUX) && !defined(__arm__) && !defined(__aarch64__) && !defined(__powerpc64__) && \
!defined(PTRACE_GET_THREAD_AREA)
// Also include asm/ptrace-abi.h since ptrace.h in older libc (for instance
// the one in Ubuntu 16.04 LTS) is missing PTRACE_GET_THREAD_AREA.
// asm/ptrace-abi.h doesn't exist on arm32 and PTRACE_GET_THREAD_AREA isn't
// defined on aarch64, so don't try to include this on those platforms.
#include <asm/ptrace-abi.h>
#endif
// On PPC64, TCGETS is defined in terms of struct termios, so we must include termios.h
#ifdef __powerpc64__
#include <termios.h>
#endif
#if BUILDFLAG(IS_ANDROID)
#if !defined(F_DUPFD_CLOEXEC)
#define F_DUPFD_CLOEXEC (F_LINUX_SPECIFIC_BASE + 6)
#endif
#endif // BUILDFLAG(IS_ANDROID)
#if defined(__arm__) && !defined(MAP_STACK)
#define MAP_STACK 0x20000 // Daisy build environment has old headers.
#endif
#if defined(__mips__) && !defined(MAP_STACK)
#define MAP_STACK 0x40000
#endif
// Temporary definitions for Arm's Memory Tagging Extension (MTE) and Branch
// Target Identification (BTI).
#if defined(ARCH_CPU_ARM64)
#define PROT_MTE 0x20
#define PROT_BTI 0x10
#endif
namespace {
inline bool IsArchitectureX86_64() {
#if defined(__x86_64__)
return true;
#else
return false;
#endif
}
inline bool IsArchitectureI386() {
#if defined(__i386__)
return true;
#else
return false;
#endif
}
inline bool IsAndroid() {
#if BUILDFLAG(IS_ANDROID)
return true;
#else
return false;
#endif
}
inline bool IsArchitectureMips() {
#if defined(__mips__)
return true;
#else
return false;
#endif
}
inline bool IsArchitecturePPC64() {
#if defined(__powerpc64__)
return true;
#else
return false;
#endif
}
// Ubuntu's version of glibc has a race condition in sem_post that can cause
// it to call futex(2) with bogus op arguments. To workaround this, we need
// to allow those futex(2) calls to fail with EINVAL, instead of crashing the
// process. See crbug.com/598471.
inline bool IsBuggyGlibcSemPost() {
#if defined(LIBC_GLIBC) && !BUILDFLAG(IS_CHROMEOS)
return true;
#else
return false;
#endif
}
} // namespace.
using sandbox::bpf_dsl::Allow;
using sandbox::bpf_dsl::Arg;
using sandbox::bpf_dsl::BoolExpr;
using sandbox::bpf_dsl::Error;
using sandbox::bpf_dsl::If;
using sandbox::bpf_dsl::ResultExpr;
namespace sandbox {
// Allow Glibc's and Android pthread creation flags, crash on any other
// thread creation attempts and EPERM attempts to use neither
// CLONE_VM nor CLONE_THREAD (all fork implementations), unless CLONE_VFORK is
// present (as in newer versions of posix_spawn).
ResultExpr RestrictCloneToThreadsAndEPERMFork() {
const Arg<unsigned long> flags(0);
// TODO(mdempsky): Extend DSL to support (flags & ~mask1) == mask2.
const uint64_t kAndroidCloneMask = CLONE_VM | CLONE_FS | CLONE_FILES |
CLONE_SIGHAND | CLONE_THREAD |
CLONE_SYSVSEM;
const uint64_t kObsoleteAndroidCloneMask = kAndroidCloneMask | CLONE_DETACHED;
const uint64_t kGlibcPthreadFlags =
CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND | CLONE_THREAD |
CLONE_SYSVSEM | CLONE_SETTLS | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID;
const BoolExpr glibc_test = flags == kGlibcPthreadFlags;
const BoolExpr android_test =
AnyOf(flags == kAndroidCloneMask, flags == kObsoleteAndroidCloneMask,
flags == kGlibcPthreadFlags);
// The following two flags are the two important flags in any vfork-emulating
// clone call. EPERM any clone call that contains both of them.
const uint64_t kImportantCloneVforkFlags = CLONE_VFORK | CLONE_VM;
const BoolExpr is_fork_or_clone_vfork =
AnyOf((flags & (CLONE_VM | CLONE_THREAD)) == 0,
(flags & kImportantCloneVforkFlags) == kImportantCloneVforkFlags);
return If(IsAndroid() ? android_test : glibc_test, Allow())
.ElseIf(is_fork_or_clone_vfork, Error(EPERM))
.Else(CrashSIGSYSClone());
}
#ifndef PR_PAC_RESET_KEYS
#define PR_PAC_RESET_KEYS 54
#endif
ResultExpr RestrictPrctl() {
// Will need to add seccomp compositing in the future. PR_SET_PTRACER is
// used by breakpad but not needed anymore.
const Arg<int> option(0), arg(1);
return Switch(option)
.Cases({PR_GET_NAME, PR_SET_NAME, PR_GET_DUMPABLE, PR_SET_DUMPABLE
#if BUILDFLAG(IS_ANDROID)
, PR_SET_PTRACER, PR_SET_TIMERSLACK
, PR_GET_NO_NEW_PRIVS
#if defined(ARCH_CPU_ARM64)
,
PR_PAC_RESET_KEYS
// PR_GET_TAGGED_ADDR_CTRL is used by debuggerd to report
// whether memory tagging is active.
,
PR_GET_TAGGED_ADDR_CTRL
// PR_PAC_GET_ENABLED_KEYS is used by debuggerd to report
// whether pointer authentication is enabled and which keys (A
// or B) are active.
,
PR_PAC_GET_ENABLED_KEYS
#endif
// Enable PR_SET_TIMERSLACK_PID, an Android custom prctl which is used in:
// https://android.googlesource.com/platform/system/core/+/lollipop-release/libcutils/sched_policy.c.
// Depending on the Android kernel version, this prctl may have different
// values. Since we don't know the correct value for the running kernel, we must
// allow them all.
//
// The effect is:
// On 3.14 kernels, this allows PR_SET_TIMERSLACK_PID and 43 and 127 (invalid
// prctls which will return EINVAL)
// On 3.18 kernels, this allows PR_SET_TIMERSLACK_PID, PR_SET_THP_DISABLE, and
// 127 (invalid).
// On 4.1 kernels and up, this allows PR_SET_TIMERSLACK_PID, PR_SET_THP_DISABLE,
// and PR_MPX_ENABLE_MANAGEMENT.
// https://android.googlesource.com/kernel/common/+/android-3.14/include/uapi/linux/prctl.h
#define PR_SET_TIMERSLACK_PID_1 41
// https://android.googlesource.com/kernel/common/+/android-3.18/include/uapi/linux/prctl.h
#define PR_SET_TIMERSLACK_PID_2 43
// https://android.googlesource.com/kernel/common/+/android-4.1/include/uapi/linux/prctl.h and up
#define PR_SET_TIMERSLACK_PID_3 127
, PR_SET_TIMERSLACK_PID_1
, PR_SET_TIMERSLACK_PID_2
, PR_SET_TIMERSLACK_PID_3
#endif // BUILDFLAG(IS_ANDROID)
},
Allow())
.Cases({PR_SET_VMA},
If(arg == PR_SET_VMA_ANON_NAME, Allow()).Else(CrashSIGSYSPrctl()))
.Default(
If(option == PR_SET_PTRACER, Error(EPERM)).Else(CrashSIGSYSPrctl()));
}
ResultExpr RestrictIoctl() {
const Arg<int> request(1);
return Switch(request).Cases({TCGETS, FIONREAD}, Allow()).Default(
CrashSIGSYSIoctl());
}
ResultExpr RestrictMmapFlags() {
#if BUILDFLAG(IS_ANDROID) && defined(__x86_64__)
const uint64_t kArchSpecificAllowedMask = MAP_32BIT;
#else
const uint64_t kArchSpecificAllowedMask = 0;
#endif
// The flags MAP_HUGETLB and MAP_POPULATE are specifically not permitted.
// TODO(davidung), remove MAP_DENYWRITE with updated Tegra libraries.
const uint64_t kAllowedMask = MAP_SHARED | MAP_PRIVATE | MAP_ANONYMOUS |
MAP_STACK | MAP_NORESERVE | MAP_FIXED |
MAP_DENYWRITE | MAP_LOCKED |
kArchSpecificAllowedMask;
const Arg<int> flags(3);
return If((flags & ~kAllowedMask) == 0, Allow()).Else(CrashSIGSYS());
}
ResultExpr RestrictMprotectFlags() {
// The flags you see are actually the allowed ones, and the variable is a
// "denied" mask because of the negation operator.
// Significantly, we don't permit weird undocumented flags such as
// PROT_GROWSDOWN.
#if defined(ARCH_CPU_ARM64)
// Allows PROT_MTE and PROT_BTI (as explained higher up) on only Arm
// platforms.
const uint64_t kArchSpecificFlags = PROT_MTE | PROT_BTI;
#else
const uint64_t kArchSpecificFlags = 0;
#endif
const uint64_t kAllowedMask =
PROT_READ | PROT_WRITE | PROT_EXEC | kArchSpecificFlags;
const Arg<int> prot(2);
return If((prot & ~kAllowedMask) == 0, Allow()).Else(CrashSIGSYS());
}
ResultExpr RestrictFcntlCommands() {
// We also restrict the flags in F_SETFL. We don't want to permit flags with
// a history of trouble such as O_DIRECT. The flags you see are actually the
// allowed ones, and the variable is a "denied" mask because of the negation
// operator.
// Glibc overrides the kernel's O_LARGEFILE value. Account for this.
uint64_t kOLargeFileFlag = O_LARGEFILE;
if (IsArchitectureX86_64() || IsArchitectureI386() || IsArchitectureMips() \
|| IsArchitecturePPC64())
kOLargeFileFlag = 0100000;
const Arg<int> cmd(1);
const Arg<long> long_arg(2);
const uint64_t kAllowedMask = O_ACCMODE | O_APPEND | O_NONBLOCK | O_SYNC |
kOLargeFileFlag | O_CLOEXEC | O_NOATIME;
#if BUILDFLAG(IS_ANDROID)
const uint64_t kOsSpecificSeals = F_SEAL_FUTURE_WRITE;
#else
const uint64_t kOsSpecificSeals = 0;
#endif
const uint64_t kAllowedSeals = F_SEAL_SEAL | F_SEAL_GROW | F_SEAL_SHRINK |
kOsSpecificSeals;
// clang-format off
return Switch(cmd)
.Cases({F_GETFL,
F_GETFD,
F_GET_SEALS,
F_SETFD,
F_SETLK,
F_SETLKW,
F_GETLK,
F_DUPFD,
F_DUPFD_CLOEXEC
#if defined(__powerpc64__)
// On PPC64, F_SETLK, F_GETLK, F_SETLKW are defined as the 64-bit variants
// but glibc will sometimes still use the 32-bit versions. Allow both.
,
5, /* F_GETLK (32) */
6, /* F_SETLK (32) */
7 /* F_SETLKW (32) */
#endif
},
Allow())
.Case(F_SETFL,
If((long_arg & ~kAllowedMask) == 0, Allow()).Else(CrashSIGSYS()))
.Case(F_ADD_SEALS,
If((long_arg & ~kAllowedSeals) == 0, Allow()).Else(CrashSIGSYS()))
.Default(CrashSIGSYS());
// clang-format on
}
#if defined(__i386__) || defined(__mips__) || defined(__powerpc64__)
ResultExpr RestrictSocketcallCommand() {
// Unfortunately, we are unable to restrict the first parameter to
// socketpair(2). Whilst initially sounding bad, it's noteworthy that very
// few protocols actually support socketpair(2). The scary call that we're
// worried about, socket(2), remains blocked.
const Arg<int> call(0);
return Switch(call)
.Cases({SYS_SOCKETPAIR,
SYS_SHUTDOWN,
SYS_RECV,
SYS_SEND,
SYS_RECVFROM,
SYS_SENDTO,
SYS_RECVMSG,
SYS_SENDMSG},
Allow())
.Default(Error(EPERM));
}
#endif
ResultExpr RestrictKillTarget(pid_t target_pid, int sysno) {
switch (sysno) {
case __NR_kill:
case __NR_tgkill: {
const Arg<pid_t> pid(0);
return If(pid == target_pid, Allow()).Else(CrashSIGSYSKill());
}
case __NR_tkill:
return CrashSIGSYSKill();
default:
NOTREACHED();
}
}
ResultExpr RestrictFutex() {
const uint64_t kAllowedFutexFlags = FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME;
ResultExpr error = IsBuggyGlibcSemPost() ? Error(EINVAL) : CrashSIGSYSFutex();
const Arg<int> op(1);
return Switch(op & ~kAllowedFutexFlags)
.Cases({FUTEX_WAIT, FUTEX_WAKE, FUTEX_REQUEUE, FUTEX_CMP_REQUEUE,
FUTEX_WAKE_OP, FUTEX_WAIT_BITSET, FUTEX_WAKE_BITSET},
Allow())
#if BUILDFLAG(ENABLE_MUTEX_PRIORITY_INHERITANCE)
// Priority-inheritance futex operations are enabled only on Android
// kernels 6.1+. Bionic uses the PI variants of the futex operations
// (FUTEX_LOCK_PI2, FUTEX_UNLOCK_PI) to implement priority inheriting
// mutexes.
.Cases({FUTEX_LOCK_PI, FUTEX_UNLOCK_PI, FUTEX_TRYLOCK_PI,
FUTEX_WAIT_REQUEUE_PI, FUTEX_CMP_REQUEUE_PI, FUTEX_LOCK_PI2},
(base::KernelSupportsPriorityInheritanceFutex() &&
(base::FeatureList::IsEnabled(
base::features::kUsePriorityInheritanceMutex) ||
base::FeatureList::IsEnabled(
base::features::
kPartitionAllocUsePriorityInheritanceLocks))
? Allow()
: error))
#endif // BUILDFLAG(ENABLE_MUTEX_PRIORITY_INHERITANCE)
.Default(error);
}
ResultExpr RestrictGetSetpriority(pid_t target_pid) {
const Arg<int> which(0);
const Arg<int> who(1);
return If(which == PRIO_PROCESS,
Switch(who).Cases({0, target_pid}, Allow()).Default(Error(EPERM)))
.Else(CrashSIGSYS());
}
ResultExpr RestrictSchedTarget(pid_t target_pid, int sysno) {
switch (sysno) {
case __NR_sched_getaffinity:
case __NR_sched_getattr:
case __NR_sched_getparam:
case __NR_sched_getscheduler:
case __NR_sched_rr_get_interval:
#if defined(__i386__) || defined(__arm__) || \
(defined(ARCH_CPU_MIPS_FAMILY) && defined(ARCH_CPU_32_BITS))
case __NR_sched_rr_get_interval_time64:
#endif
case __NR_sched_setaffinity:
case __NR_sched_setattr:
case __NR_sched_setparam:
case __NR_sched_setscheduler: {
const Arg<pid_t> pid(0);
return Switch(pid)
.Cases({0, target_pid}, Allow())
.Default(RewriteSchedSIGSYS());
}
default:
NOTREACHED();
}
}
ResultExpr RestrictPrlimit64(pid_t target_pid) {
const Arg<pid_t> pid(0);
return Switch(pid).Cases({0, target_pid}, Allow()).Default(CrashSIGSYS());
}
ResultExpr RestrictGetrusage() {
const Arg<int> who(0);
return If(AnyOf(who == RUSAGE_SELF, who == RUSAGE_THREAD), Allow())
.Else(CrashSIGSYS());
}
ResultExpr RestrictClockID() {
static_assert(4 == sizeof(clockid_t), "clockid_t is not 32bit");
const Arg<clockid_t> clockid(0);
// Clock IDs < 0 are per pid/tid or are clockfds.
const unsigned int kIsPidBit = 1u<<31;
return
If((clockid & kIsPidBit) == 0,
Switch(clockid).Cases({
CLOCK_BOOTTIME,
CLOCK_MONOTONIC,
CLOCK_MONOTONIC_COARSE,
CLOCK_MONOTONIC_RAW,
CLOCK_PROCESS_CPUTIME_ID,
CLOCK_REALTIME,
CLOCK_REALTIME_COARSE,
CLOCK_THREAD_CPUTIME_ID},
Allow())
.Default(CrashSIGSYS()))
#if BUILDFLAG(IS_ANDROID)
// Allow per-pid and per-tid clocks.
.ElseIf((clockid & CPUCLOCK_CLOCK_MASK) != CLOCKFD, Allow())
#endif
.Else(CrashSIGSYS());
}
#if !defined(GRND_NONBLOCK)
#define GRND_NONBLOCK 1
#endif
#if !defined(GRND_INSECURE)
#define GRND_INSECURE 4
#endif
ResultExpr RestrictGetRandom() {
const Arg<unsigned int> flags(2);
const unsigned int kGoodFlags = GRND_NONBLOCK | GRND_INSECURE;
return If((flags & ~kGoodFlags) == 0, Allow()).Else(CrashSIGSYS());
}
ResultExpr RestrictPrlimit(pid_t target_pid) {
const Arg<pid_t> pid(0);
// Only allow operations for the current process.
return If(AnyOf(pid == 0, pid == target_pid), Allow()).Else(Error(EPERM));
}
ResultExpr RestrictPrlimitToGetrlimit(pid_t target_pid) {
const Arg<pid_t> pid(0);
const Arg<uintptr_t> new_limit(2);
// Only allow operations for the current process, and only with |new_limit|
// set to null.
return If(AllOf(new_limit == 0, AnyOf(pid == 0, pid == target_pid)), Allow())
.Else(Error(EPERM));
}
ResultExpr RestrictPtrace() {
const Arg<int> request(0);
#if defined(__aarch64__)
const Arg<uintptr_t> addr(2);
#endif
return Switch(request)
.Cases({
#if !defined(__aarch64__) && !defined(__powerpc64__)
PTRACE_GETREGS, PTRACE_GETFPREGS, PTRACE_GET_THREAD_AREA,
PTRACE_GETREGSET,
#endif
#if defined(__arm__)
PTRACE_GETVFPREGS,
#endif
PTRACE_PEEKDATA, PTRACE_ATTACH, PTRACE_DETACH},
Allow())
#if defined(__aarch64__)
.Case(
PTRACE_GETREGSET,
If(AllOf(addr != NT_ARM_PACA_KEYS, addr != NT_ARM_PACG_KEYS), Allow())
.Else(CrashSIGSYSPtrace()))
#endif
.Default(CrashSIGSYSPtrace());
}
ResultExpr RestrictPkeyAllocFlags() {
const Arg<int> flags(0);
return If(flags == 0, Allow()).Else(CrashSIGSYS());
}
ResultExpr RestrictGoogle3Threading(int sysno) {
DCHECK(sysno == __NR_getitimer || sysno == __NR_setitimer);
const Arg<int> which(0);
return If(which == ITIMER_PROF, Allow()).Else(Error(EPERM));
}
ResultExpr RestrictPipe2() {
const Arg<int> flags(1);
return If((flags & ~(O_CLOEXEC|O_DIRECT|O_NONBLOCK)) == 0, Allow())
.Else(CrashSIGSYS());
}
} // namespace sandbox.
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