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sandboxed-api/sandboxed_api/sandbox2/regs.cc

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// Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Implementation of the sandbox2::Regs class.
#include "sandboxed_api/sandbox2/regs.h"
#include <elf.h> // IWYU pragma: keep // used for NT_PRSTATUS inside an ifdef
#include <sys/ptrace.h>
#include <sys/uio.h> // IWYU pragma: keep // used for iovec
#include <cerrno>
#include <cstdint>
#include "absl/base/optimization.h"
#include "absl/status/status.h"
#include "absl/strings/str_cat.h"
#include "sandboxed_api/config.h"
namespace sandbox2 {
#ifndef NT_ARM_SYSTEM_CALL
#define NT_ARM_SYSTEM_CALL 0x404
#endif
absl::Status Regs::Fetch() {
#ifdef SAPI_X86_64
if (ptrace(PTRACE_GETREGS, pid_, 0, &user_regs_) == -1L) {
return absl::ErrnoToStatus(
errno, absl::StrCat("ptrace(PTRACE_GETREGS, pid=", pid_, ") failed"));
}
#endif
if constexpr (sapi::host_cpu::IsPPC64LE() || sapi::host_cpu::IsArm64() ||
sapi::host_cpu::IsArm()) {
iovec pt_iov = {&user_regs_, sizeof(user_regs_)};
if (ptrace(PTRACE_GETREGSET, pid_, NT_PRSTATUS, &pt_iov) == -1L) {
return absl::ErrnoToStatus(
errno,
absl::StrCat("ptrace(PTRACE_GETREGSET, pid=", pid_, ") failed"));
}
if (pt_iov.iov_len != sizeof(user_regs_)) {
return absl::InternalError(absl::StrCat(
"ptrace(PTRACE_GETREGSET, pid=", pid_,
") size returned: ", pt_iov.iov_len,
" different than sizeof(user_regs_): ", sizeof(user_regs_)));
}
// On AArch64, we are not done yet. Read the syscall number.
if constexpr (sapi::host_cpu::IsArm64()) {
iovec sys_iov = {&syscall_number_, sizeof(syscall_number_)};
if (ptrace(PTRACE_GETREGSET, pid_, NT_ARM_SYSTEM_CALL, &sys_iov) == -1L) {
return absl::ErrnoToStatus(
errno, absl::StrCat("ptrace(PTRACE_GETREGSET, pid=", pid_,
", NT_ARM_SYSTEM_CALL)"));
}
if (sys_iov.iov_len != sizeof(syscall_number_)) {
return absl::InternalError(absl::StrCat(
"ptrace(PTRACE_GETREGSET, pid=", pid_,
", NT_ARM_SYSTEM_CALL) size returned: ", sys_iov.iov_len,
" different than sizeof(syscall_number_): ",
sizeof(syscall_number_)));
}
}
}
return absl::OkStatus();
}
absl::Status Regs::Store() {
#ifdef SAPI_X86_64
if (ptrace(PTRACE_SETREGS, pid_, 0, &user_regs_) == -1) {
return absl::ErrnoToStatus(
errno, absl::StrCat("ptrace(PTRACE_SETREGS, pid=", pid_, ")"));
}
#endif
if constexpr (sapi::host_cpu::IsPPC64LE() || sapi::host_cpu::IsArm64() ||
sapi::host_cpu::IsArm()) {
iovec pt_iov = {&user_regs_, sizeof(user_regs_)};
if (ptrace(PTRACE_SETREGSET, pid_, NT_PRSTATUS, &pt_iov) == -1L) {
return absl::ErrnoToStatus(
errno,
absl::StrCat("ptrace(PTRACE_SETREGSET, pid=", pid_, ") failed"));
}
// Store syscall number on AArch64.
if constexpr (sapi::host_cpu::IsArm64()) {
iovec sys_iov = {&syscall_number_, sizeof(syscall_number_)};
if (ptrace(PTRACE_SETREGSET, pid_, NT_ARM_SYSTEM_CALL, &sys_iov) == -1L) {
return absl::ErrnoToStatus(
errno, absl::StrCat("ptrace(PTRACE_SETREGSET, pid=", pid_,
", NT_ARM_SYSTEM_CALL) failed"));
}
}
}
return absl::OkStatus();
}
absl::Status Regs::SkipSyscallReturnValue(uintptr_t value) {
#if defined(SAPI_X86_64)
user_regs_.orig_rax = -1;
user_regs_.rax = value;
#elif defined(SAPI_PPC64_LE)
user_regs_.gpr[0] = -1;
user_regs_.gpr[3] = value;
#elif defined(SAPI_ARM64)
syscall_number_ = -1;
user_regs_.regs[0] = value;
#elif defined(SAPI_ARM)
user_regs_.orig_x0 = -1;
user_regs_.regs[7] = value;
#endif
return Store();
}
Syscall Regs::ToSyscall(sapi::cpu::Architecture syscall_arch) const {
#if defined(SAPI_X86_64)
if (ABSL_PREDICT_TRUE(syscall_arch == sapi::cpu::kX8664)) {
auto syscall = user_regs_.orig_rax;
Syscall::Args args = {user_regs_.rdi, user_regs_.rsi, user_regs_.rdx,
user_regs_.r10, user_regs_.r8, user_regs_.r9};
auto sp = user_regs_.rsp;
auto ip = user_regs_.rip;
return Syscall(syscall_arch, syscall, args, pid_, sp, ip);
}
if (syscall_arch == sapi::cpu::kX86) {
auto syscall = user_regs_.orig_rax & 0xFFFFFFFF;
Syscall::Args args = {
user_regs_.rbx & 0xFFFFFFFF, user_regs_.rcx & 0xFFFFFFFF,
user_regs_.rdx & 0xFFFFFFFF, user_regs_.rsi & 0xFFFFFFFF,
user_regs_.rdi & 0xFFFFFFFF, user_regs_.rbp & 0xFFFFFFFF};
auto sp = user_regs_.rsp & 0xFFFFFFFF;
auto ip = user_regs_.rip & 0xFFFFFFFF;
return Syscall(syscall_arch, syscall, args, pid_, sp, ip);
}
#elif defined(SAPI_PPC64_LE)
if (ABSL_PREDICT_TRUE(syscall_arch == sapi::cpu::kPPC64LE)) {
auto syscall = user_regs_.gpr[0];
Syscall::Args args = {user_regs_.orig_gpr3, user_regs_.gpr[4],
user_regs_.gpr[5], user_regs_.gpr[6],
user_regs_.gpr[7], user_regs_.gpr[8]};
auto sp = user_regs_.gpr[1];
auto ip = user_regs_.nip;
return Syscall(syscall_arch, syscall, args, pid_, sp, ip);
}
#elif defined(SAPI_ARM64)
if (ABSL_PREDICT_TRUE(syscall_arch == sapi::cpu::kArm64)) {
Syscall::Args args = {
// First argument should be orig_x0, which is not available to ptrace on
// AArch64 (see
// https://undo.io/resources/arm64-vs-arm32-whats-different-linux-programmers/),
// as it will have been overwritten. For our use case, though, using
// regs[0] is fine, as we are always called on syscall entry and never
// on exit.
user_regs_.regs[0], user_regs_.regs[1], user_regs_.regs[2],
user_regs_.regs[3], user_regs_.regs[4], user_regs_.regs[5],
};
auto sp = user_regs_.sp;
auto ip = user_regs_.pc;
return Syscall(syscall_arch, syscall_number_, args, pid_, sp, ip);
}
#elif defined(SAPI_ARM)
if (ABSL_PREDICT_TRUE(syscall_arch == sapi::cpu::kArm)) {
Syscall::Args args = {
user_regs_.orig_x0, user_regs_.regs[1], user_regs_.regs[2],
user_regs_.regs[3], user_regs_.regs[4], user_regs_.regs[5],
};
auto sp = user_regs_.regs[13];
auto ip = user_regs_.pc;
return Syscall(syscall_arch, user_regs_.regs[7], args, pid_, sp, ip);
}
#endif
return Syscall(pid_);
}
int64_t Regs::GetReturnValue(sapi::cpu::Architecture syscall_arch) const {
#if defined(SAPI_X86_64)
if (ABSL_PREDICT_TRUE(syscall_arch == sapi::cpu::kX8664)) {
return static_cast<int64_t>(user_regs_.rax);
}
if (syscall_arch == sapi::cpu::kX86) {
return static_cast<int32_t>(user_regs_.rax & 0xFFFFFFFF);
}
#elif defined(SAPI_PPC64_LE)
if (ABSL_PREDICT_TRUE(syscall_arch == sapi::cpu::kPPC64LE)) {
return static_cast<int64_t>(user_regs_.gpr[3]);
}
#elif defined(SAPI_ARM64)
if (ABSL_PREDICT_TRUE(syscall_arch == sapi::cpu::kArm64)) {
return static_cast<int64_t>(user_regs_.regs[0]);
}
#elif defined(SAPI_ARM)
if (ABSL_PREDICT_TRUE(syscall_arch == sapi::cpu::kArm)) {
return static_cast<int32_t>(user_regs_.regs[0]);
}
#endif
return -1;
}
void Regs::StoreRegisterValuesInProtobuf(RegisterValues* values) const {
#if defined(SAPI_X86_64)
RegisterX8664* regs = values->mutable_register_x86_64();
regs->set_r15(user_regs_.r15);
regs->set_r14(user_regs_.r14);
regs->set_r13(user_regs_.r13);
regs->set_r12(user_regs_.r12);
regs->set_rbp(user_regs_.rbp);
regs->set_rbx(user_regs_.rbx);
regs->set_r11(user_regs_.r11);
regs->set_r10(user_regs_.r10);
regs->set_r9(user_regs_.r9);
regs->set_r8(user_regs_.r8);
regs->set_rax(user_regs_.rax);
regs->set_rcx(user_regs_.rcx);
regs->set_rdx(user_regs_.rdx);
regs->set_rsi(user_regs_.rsi);
regs->set_rdi(user_regs_.rdi);
regs->set_orig_rax(user_regs_.orig_rax);
regs->set_rip(user_regs_.rip);
regs->set_cs(user_regs_.cs);
regs->set_eflags(user_regs_.eflags);
regs->set_rsp(user_regs_.rsp);
regs->set_ss(user_regs_.ss);
regs->set_fs_base(user_regs_.fs_base);
regs->set_gs_base(user_regs_.gs_base);
regs->set_ds(user_regs_.ds);
regs->set_es(user_regs_.es);
regs->set_fs(user_regs_.fs);
regs->set_gs(user_regs_.gs);
#elif defined(SAPI_PPC64_LE)
RegisterPowerpc64* regs = values->mutable_register_powerpc64();
for (int i = 0; i < ABSL_ARRAYSIZE(user_regs_.gpr); ++i) {
regs->add_gpr(user_regs_.gpr[i]);
}
regs->set_nip(user_regs_.nip);
regs->set_msr(user_regs_.msr);
regs->set_orig_gpr3(user_regs_.orig_gpr3);
regs->set_ctr(user_regs_.ctr);
regs->set_link(user_regs_.link);
regs->set_xer(user_regs_.xer);
regs->set_ccr(user_regs_.ccr);
regs->set_softe(user_regs_.softe);
regs->set_trap(user_regs_.trap);
regs->set_dar(user_regs_.dar);
regs->set_dsisr(user_regs_.dsisr);
regs->set_result(user_regs_.result);
regs->set_zero0(user_regs_.zero0);
regs->set_zero1(user_regs_.zero1);
regs->set_zero2(user_regs_.zero2);
regs->set_zero3(user_regs_.zero3);
#elif defined(SAPI_ARM64)
RegisterAarch64* regs = values->mutable_register_aarch64();
for (int i = 0; i < ABSL_ARRAYSIZE(user_regs_.regs); ++i) {
regs->add_regs(user_regs_.regs[i]);
}
regs->set_sp(user_regs_.sp);
regs->set_pc(user_regs_.pc);
regs->set_pstate(user_regs_.pstate);
#elif defined(SAPI_ARM)
RegisterArm* regs = values->mutable_register_arm();
for (int i = 0; i < ABSL_ARRAYSIZE(user_regs_.regs); ++i) {
regs->add_regs(user_regs_.regs[i]);
}
regs->set_pc(user_regs_.pc);
regs->set_cpsr(user_regs_.cpsr);
regs->set_orig_x0(user_regs_.orig_x0);
#endif
}
} // namespace sandbox2
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