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Use SyscallTrap in NetworkProxy

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PiperOrigin-RevId: 491891500
Change-Id: I2e70dbc44aa264247c217ca88a4de1c0867383fd
This commit is contained in:
Wiktor Garbacz 2022-11-30 05:47:09 -08:00 committed by Copybara-Service
parent 5bf9b1aef0
commit bd5769d40a
4 changed files with 27 additions and 121 deletions
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3
sandboxed_api/sandbox2/network_proxy/BUILD.bazel
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@ -43,11 +43,10 @@ cc_library(
copts = sapi_platform_copts(),
visibility = ["//visibility:public"],
deps = [
"//sandboxed_api:config",
"//sandboxed_api/sandbox2:comms",
"//sandboxed_api/sandbox2/util:syscall_trap",
"//sandboxed_api/util:status",
"@com_google_absl//absl/log",
"@com_google_absl//absl/log:check",
"@com_google_absl//absl/status",
"@com_google_absl//absl/synchronization",
],

3
sandboxed_api/sandbox2/network_proxy/CMakeLists.txt
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@ -49,12 +49,11 @@ add_library(sandbox2_network_proxy_client ${SAPI_LIB_TYPE}
)
add_library(sandbox2::network_proxy_client ALIAS sandbox2_network_proxy_client)
target_link_libraries(sandbox2_network_proxy_client PRIVATE
absl::check
absl::strings
absl::synchronization
absl::log
sandbox2::comms
sapi::config
sandbox2::syscall_trap
sapi::strerror
sapi::base
sapi::status

128
sandboxed_api/sandbox2/network_proxy/client.cc
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@ -18,50 +18,18 @@
#include <linux/seccomp.h>
#include <stdio.h>
#include <syscall.h>
#include <ucontext.h>
#include <cerrno>
#include <iostream>
#include <memory>
#include "absl/log/check.h"
#include "absl/log/log.h"
#include "absl/status/status.h"
#include "sandboxed_api/config.h"
#include "sandboxed_api/sandbox2/util/syscall_trap.h"
#include "sandboxed_api/util/status_macros.h"
namespace sandbox2 {
#ifndef SYS_SECCOMP
constexpr int SYS_SECCOMP = 1;
#endif
#if defined(SAPI_X86_64)
constexpr int kRegResult = REG_RAX;
constexpr int kRegSyscall = REG_RAX;
constexpr int kRegArg0 = REG_RDI;
constexpr int kRegArg1 = REG_RSI;
constexpr int kRegArg2 = REG_RDX;
#elif defined(SAPI_PPC64_LE)
constexpr int kRegResult = 3;
constexpr int kRegSyscall = 0;
constexpr int kRegArg0 = 3;
constexpr int kRegArg1 = 4;
constexpr int kRegArg2 = 5;
#elif defined(SAPI_ARM64)
constexpr int kRegResult = 0;
constexpr int kRegSyscall = 8;
constexpr int kRegArg0 = 0;
constexpr int kRegArg1 = 1;
constexpr int kRegArg2 = 2;
#elif defined(SAPI_ARM)
constexpr int kRegResult = 0;
constexpr int kRegSyscall = 8;
constexpr int kRegArg0 = 0;
constexpr int kRegArg1 = 1;
constexpr int kRegArg2 = 2;
#endif
int NetworkProxyClient::ConnectHandler(int sockfd, const struct sockaddr* addr,
socklen_t addrlen) {
absl::Status status = Connect(sockfd, addr, addrlen);
@ -124,104 +92,52 @@ absl::Status NetworkProxyClient::ReceiveRemoteResult() {
return absl::OkStatus();
}
namespace {
static NetworkProxyHandler* g_network_proxy_handler = nullptr;
void SignalHandler(int nr, siginfo_t* info, void* void_context) {
g_network_proxy_handler->ProcessSeccompTrap(nr, info, void_context);
}
} // namespace
NetworkProxyClient* NetworkProxyHandler::network_proxy_client_ = nullptr;
absl::Status NetworkProxyHandler::InstallNetworkProxyHandler(
NetworkProxyClient* npc) {
if (g_network_proxy_handler) {
if (network_proxy_client_ != nullptr) {
return absl::AlreadyExistsError(
"Network proxy handler is already installed");
}
g_network_proxy_handler = new NetworkProxyHandler(npc);
network_proxy_client_ = npc;
if (!SyscallTrap::Install([](int nr, SyscallTrap::Args args, uintptr_t* rv) {
return ProcessSeccompTrap(nr, args, rv);
})) {
return absl::InternalError("Could not install syscall trap");
}
return absl::OkStatus();
}
void NetworkProxyHandler::InvokeOldAct(int nr, siginfo_t* info,
void* void_context) {
if (oldact_.sa_flags & SA_SIGINFO) {
if (oldact_.sa_sigaction) {
oldact_.sa_sigaction(nr, info, void_context);
}
} else if (oldact_.sa_handler == SIG_IGN) {
return;
} else if (oldact_.sa_handler == SIG_DFL) {
sigaction(SIGSYS, &oldact_, nullptr);
raise(SIGSYS);
} else if (oldact_.sa_handler) {
oldact_.sa_handler(nr);
}
} // namespace sandbox2
void NetworkProxyHandler::ProcessSeccompTrap(int nr, siginfo_t* info,
void* void_context) {
if (info->si_code != SYS_SECCOMP) {
InvokeOldAct(nr, info, void_context);
return;
}
auto* ctx = static_cast<ucontext_t*>(void_context);
if (!ctx) {
return;
}
#if defined(SAPI_X86_64)
auto* registers = ctx->uc_mcontext.gregs;
#elif defined(SAPI_PPC64_LE)
auto* registers = ctx->uc_mcontext.gp_regs;
#elif defined(SAPI_ARM64)
auto* registers = ctx->uc_mcontext.regs;
#elif defined(SAPI_ARM)
auto* registers = &ctx->uc_mcontext.arm_r0;
#endif
int syscall = registers[kRegSyscall];
bool NetworkProxyHandler::ProcessSeccompTrap(int nr, SyscallTrap::Args args,
uintptr_t* rv) {
int sockfd;
const struct sockaddr* addr;
socklen_t addrlen;
if (syscall == __NR_connect) {
sockfd = static_cast<int>(registers[kRegArg0]);
addr = reinterpret_cast<const struct sockaddr*>(registers[kRegArg1]);
addrlen = static_cast<socklen_t>(registers[kRegArg2]);
if (nr == __NR_connect) {
sockfd = static_cast<int>(args[0]);
addr = reinterpret_cast<const struct sockaddr*>(args[1]);
addrlen = static_cast<socklen_t>(args[2]);
#if defined(SAPI_PPC64_LE)
} else if (syscall == __NR_socketcall &&
static_cast<int>(registers[kRegArg0]) == SYS_CONNECT) {
auto* connect_args = reinterpret_cast<uint64_t*>(registers[kRegArg1]);
} else if (nr == __NR_socketcall &&
static_cast<int>(args[0]) == SYS_CONNECT) {
auto* connect_args = reinterpret_cast<uint64_t*>(args[1]);
sockfd = static_cast<int>(connect_args[0]);
addr = reinterpret_cast<const struct sockaddr*>(connect_args[1]);
addrlen = static_cast<socklen_t>(connect_args[2]);
#endif
} else {
InvokeOldAct(nr, info, void_context);
return;
return false;
}
absl::Status result = network_proxy_client_->Connect(sockfd, addr, addrlen);
if (result.ok()) {
registers[kRegResult] = 0;
*rv = 0;
} else {
registers[kRegResult] = -errno;
*rv = -errno;
}
}
void NetworkProxyHandler::InstallSeccompTrap() {
sigset_t mask;
sigemptyset(&mask);
sigaddset(&mask, SIGSYS);
struct sigaction act = {};
act.sa_sigaction = &SignalHandler;
act.sa_flags = SA_SIGINFO;
CHECK_EQ(sigaction(SIGSYS, &act, &oldact_), 0);
CHECK_EQ(sigprocmask(SIG_UNBLOCK, &mask, nullptr), 0);
return true;
}
} // namespace sandbox2

14
sandboxed_api/sandbox2/network_proxy/client.h
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@ -16,11 +16,11 @@
#define SANDBOXED_API_SANDBOX2_NETWORK_PROXY_CLIENT_H_
#include <netinet/in.h>
#include <signal.h>
#include "absl/status/status.h"
#include "absl/synchronization/mutex.h"
#include "sandboxed_api/sandbox2/comms.h"
#include "sandboxed_api/sandbox2/util/syscall_trap.h"
namespace sandbox2 {
@ -57,17 +57,9 @@ class NetworkProxyHandler {
// if this connection is allowed and sends the connected socket to us.
static absl::Status InstallNetworkProxyHandler(NetworkProxyClient* npc);
void ProcessSeccompTrap(int nr, siginfo_t* info, void* void_context);
static bool ProcessSeccompTrap(int nr, SyscallTrap::Args args, uintptr_t* rv);
private:
NetworkProxyHandler(NetworkProxyClient* npc) : network_proxy_client_(npc) {
InstallSeccompTrap();
}
void InvokeOldAct(int nr, siginfo_t* info, void* void_context);
void InstallSeccompTrap();
struct sigaction oldact_;
NetworkProxyClient* network_proxy_client_;
static NetworkProxyClient* network_proxy_client_;
};
} // namespace sandbox2