blob: 9b27f9497f7a77b3aa4e3668656409f9e1c31296 [file] [log] [blame]
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "content/common/sandbox_linux/sandbox_seccomp_bpf_linux.h"
#include <errno.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <memory>
#include "base/command_line.h"
#include "base/logging.h"
#include "base/macros.h"
#include "build/build_config.h"
#include "content/public/common/content_switches.h"
#include "sandbox/linux/bpf_dsl/bpf_dsl.h"
#include "sandbox/sandbox_features.h"
#if BUILDFLAG(USE_SECCOMP_BPF)
#include "base/files/scoped_file.h"
#include "base/posix/eintr_wrapper.h"
#include "content/common/sandbox_linux/bpf_cros_arm_gpu_policy_linux.h"
#include "content/common/sandbox_linux/bpf_gpu_policy_linux.h"
#include "content/common/sandbox_linux/bpf_ppapi_policy_linux.h"
#include "content/common/sandbox_linux/bpf_renderer_policy_linux.h"
#include "content/common/sandbox_linux/bpf_utility_policy_linux.h"
#include "content/common/sandbox_linux/sandbox_bpf_base_policy_linux.h"
#include "sandbox/linux/seccomp-bpf-helpers/baseline_policy.h"
#include "sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h"
#include "sandbox/linux/seccomp-bpf-helpers/syscall_parameters_restrictions.h"
#include "sandbox/linux/seccomp-bpf-helpers/syscall_sets.h"
#include "sandbox/linux/seccomp-bpf/sandbox_bpf.h"
#include "sandbox/linux/system_headers/linux_syscalls.h"
using sandbox::BaselinePolicy;
using sandbox::SandboxBPF;
using sandbox::SyscallSets;
using sandbox::bpf_dsl::Allow;
using sandbox::bpf_dsl::ResultExpr;
#else
// Make sure that seccomp-bpf does not get disabled by mistake. Also make sure
// that we think twice about this when adding a new architecture.
#if !defined(ARCH_CPU_ARM64)
#error "Seccomp-bpf disabled on supported architecture!"
#endif // !defined(ARCH_CPU_ARM64)
#endif //
namespace content {
#if BUILDFLAG(USE_SECCOMP_BPF)
namespace {
// This function takes ownership of |policy|.
void StartSandboxWithPolicy(sandbox::bpf_dsl::Policy* policy,
base::ScopedFD proc_fd) {
// Starting the sandbox is a one-way operation. The kernel doesn't allow
// us to unload a sandbox policy after it has been started. Nonetheless,
// in order to make the use of the "Sandbox" object easier, we allow for
// the object to be destroyed after the sandbox has been started. Note that
// doing so does not stop the sandbox.
SandboxBPF sandbox(policy);
sandbox.SetProcFd(std::move(proc_fd));
CHECK(sandbox.StartSandbox(SandboxBPF::SeccompLevel::SINGLE_THREADED));
}
#if !defined(OS_NACL_NONSFI)
class BlacklistDebugAndNumaPolicy : public SandboxBPFBasePolicy {
public:
BlacklistDebugAndNumaPolicy() {}
~BlacklistDebugAndNumaPolicy() override {}
ResultExpr EvaluateSyscall(int system_call_number) const override;
private:
DISALLOW_COPY_AND_ASSIGN(BlacklistDebugAndNumaPolicy);
};
ResultExpr BlacklistDebugAndNumaPolicy::EvaluateSyscall(int sysno) const {
if (SyscallSets::IsDebug(sysno) || SyscallSets::IsNuma(sysno))
return sandbox::CrashSIGSYS();
return Allow();
}
class AllowAllPolicy : public SandboxBPFBasePolicy {
public:
AllowAllPolicy() {}
~AllowAllPolicy() override {}
ResultExpr EvaluateSyscall(int system_call_number) const override;
private:
DISALLOW_COPY_AND_ASSIGN(AllowAllPolicy);
};
// Allow all syscalls.
// This will still deny x32 or IA32 calls in 64 bits mode or
// 64 bits system calls in compatibility mode.
ResultExpr AllowAllPolicy::EvaluateSyscall(int sysno) const {
return Allow();
}
// nacl_helper needs to be tiny and includes only part of content/
// in its dependencies. Make sure to not link things that are not needed.
#if !defined(IN_NACL_HELPER)
inline bool IsChromeOS() {
#if defined(OS_CHROMEOS)
return true;
#else
return false;
#endif
}
inline bool IsArchitectureArm() {
#if defined(__arm__)
return true;
#else
return false;
#endif
}
// If a BPF policy is engaged for |process_type|, run a few sanity checks.
void RunSandboxSanityChecks(const std::string& process_type) {
if (process_type == switches::kRendererProcess ||
process_type == switches::kGpuProcess ||
process_type == switches::kPpapiPluginProcess) {
int syscall_ret;
errno = 0;
// Without the sandbox, this would EBADF.
syscall_ret = fchmod(-1, 07777);
CHECK_EQ(-1, syscall_ret);
CHECK_EQ(EPERM, errno);
// Run most of the sanity checks only in DEBUG mode to avoid a perf.
// impact.
#if !defined(NDEBUG)
// open() must be restricted.
syscall_ret = open("/etc/passwd", O_RDONLY);
CHECK_EQ(-1, syscall_ret);
CHECK_EQ(SandboxBPFBasePolicy::GetFSDeniedErrno(), errno);
// We should never allow the creation of netlink sockets.
syscall_ret = socket(AF_NETLINK, SOCK_DGRAM, 0);
CHECK_EQ(-1, syscall_ret);
CHECK_EQ(EPERM, errno);
#endif // !defined(NDEBUG)
}
}
std::unique_ptr<SandboxBPFBasePolicy> GetGpuProcessSandbox() {
const base::CommandLine& command_line =
*base::CommandLine::ForCurrentProcess();
if (IsChromeOS() && IsArchitectureArm()) {
bool allow_sysv_shm =
command_line.HasSwitch(switches::kGpuSandboxAllowSysVShm);
return std::unique_ptr<SandboxBPFBasePolicy>(
new CrosArmGpuProcessPolicy(allow_sysv_shm));
} else {
return std::unique_ptr<SandboxBPFBasePolicy>(new GpuProcessPolicy());
}
}
// Initialize the seccomp-bpf sandbox.
bool StartBPFSandbox(const base::CommandLine& command_line,
const std::string& process_type,
base::ScopedFD proc_fd) {
std::unique_ptr<SandboxBPFBasePolicy> policy;
if (process_type == switches::kGpuProcess) {
policy.reset(GetGpuProcessSandbox().release());
} else if (process_type == switches::kRendererProcess) {
policy.reset(new RendererProcessPolicy);
} else if (process_type == switches::kPpapiPluginProcess) {
policy.reset(new PpapiProcessPolicy);
} else if (process_type == switches::kUtilityProcess) {
policy.reset(new UtilityProcessPolicy);
} else {
NOTREACHED();
policy.reset(new AllowAllPolicy);
}
CHECK(policy->PreSandboxHook());
StartSandboxWithPolicy(policy.release(), std::move(proc_fd));
RunSandboxSanityChecks(process_type);
return true;
}
#else // defined(IN_NACL_HELPER)
bool StartBPFSandbox(const base::CommandLine& command_line,
const std::string& process_type) {
NOTREACHED();
return false;
}
#endif // !defined(IN_NACL_HELPER)
#endif // !defined(OS_NACL_NONSFI)
} // namespace
#endif // USE_SECCOMP_BPF
// Is seccomp BPF globally enabled?
bool SandboxSeccompBPF::IsSeccompBPFDesired() {
const base::CommandLine& command_line =
*base::CommandLine::ForCurrentProcess();
if (!command_line.HasSwitch(switches::kNoSandbox) &&
!command_line.HasSwitch(switches::kDisableSeccompFilterSandbox)) {
return true;
} else {
return false;
}
}
#if !defined(OS_NACL_NONSFI)
bool SandboxSeccompBPF::ShouldEnableSeccompBPF(
const std::string& process_type) {
#if BUILDFLAG(USE_SECCOMP_BPF)
const base::CommandLine& command_line =
*base::CommandLine::ForCurrentProcess();
if (process_type == switches::kGpuProcess)
return !command_line.HasSwitch(switches::kDisableGpuSandbox);
return true;
#endif // USE_SECCOMP_BPF
return false;
}
#endif // !defined(OS_NACL_NONSFI)
bool SandboxSeccompBPF::SupportsSandbox() {
#if BUILDFLAG(USE_SECCOMP_BPF)
return SandboxBPF::SupportsSeccompSandbox(
SandboxBPF::SeccompLevel::SINGLE_THREADED);
#endif
return false;
}
#if !defined(OS_NACL_NONSFI)
bool SandboxSeccompBPF::SupportsSandboxWithTsync() {
#if BUILDFLAG(USE_SECCOMP_BPF)
return SandboxBPF::SupportsSeccompSandbox(
SandboxBPF::SeccompLevel::MULTI_THREADED);
#endif
return false;
}
bool SandboxSeccompBPF::StartSandbox(const std::string& process_type,
base::ScopedFD proc_fd) {
#if BUILDFLAG(USE_SECCOMP_BPF)
const base::CommandLine& command_line =
*base::CommandLine::ForCurrentProcess();
if (IsSeccompBPFDesired() && // Global switches policy.
ShouldEnableSeccompBPF(process_type) && // Process-specific policy.
SupportsSandbox()) {
// If the kernel supports the sandbox, and if the command line says we
// should enable it, enable it or die.
bool started_sandbox =
StartBPFSandbox(command_line, process_type, std::move(proc_fd));
CHECK(started_sandbox);
return true;
}
#endif
return false;
}
#endif // !defined(OS_NACL_NONSFI)
bool SandboxSeccompBPF::StartSandboxWithExternalPolicy(
std::unique_ptr<sandbox::bpf_dsl::Policy> policy,
base::ScopedFD proc_fd) {
#if BUILDFLAG(USE_SECCOMP_BPF)
if (IsSeccompBPFDesired() && SupportsSandbox()) {
CHECK(policy);
StartSandboxWithPolicy(policy.release(), std::move(proc_fd));
return true;
}
#endif // BUILDFLAG(USE_SECCOMP_BPF)
return false;
}
#if !defined(OS_NACL_NONSFI)
std::unique_ptr<sandbox::bpf_dsl::Policy>
SandboxSeccompBPF::GetBaselinePolicy() {
#if BUILDFLAG(USE_SECCOMP_BPF)
return std::unique_ptr<sandbox::bpf_dsl::Policy>(new BaselinePolicy);
#else
return std::unique_ptr<sandbox::bpf_dsl::Policy>();
#endif // BUILDFLAG(USE_SECCOMP_BPF)
}
#endif // !defined(OS_NACL_NONSFI)
} // namespace content