Remove PTrace

CMakeLists.txt

@@ -15,6 +15,8 @@ if(NOT TRAMPOLINE_HEADERS_ONLY)
     check_symbol_exists("__x86_64__" "" USE_QEMU_TRAMPOLINE)
 
     # Include Correct Sub-Project
+    set(TRAMPOLINE_RPATH "$ORIGIN/../lib/native")
+    set(TRAMPOLINE_EXTRA_LINK_FLAG "--disable-new-dtags")
     if(USE_NATIVE_TRAMPOLINE)
         add_subdirectory(native)
         target_compile_definitions(trampoline-headers INTERFACE MCPI_USE_NATIVE_TRAMPOLINE)

include/trampoline/types.h

@@ -2,11 +2,10 @@
 
 #include <stdint.h>
 
-// Switch Between Pipe/PTrace Mode
+// Maximum Arguments Length
-#define TRAMPOLINE_USE_PIPES_ENV "_MCPI_TRAMPOLINE_USE_PIPES"
+#define MAX_TRAMPOLINE_ARGS_SIZE 2097152 // 2 MiB
 
 // System Call Constants
-#define MAX_TRAMPOLINE_ARGS_SIZE 2097152 // 2 MiB
 #define TRAMPOLINE_SYSCALL 0x1337
 
 // Pipe Constants

native/CMakeLists.txt

@@ -7,7 +7,7 @@ add_executable(trampoline
     src/trampoline.cpp
     src/ptrace/loop.cpp
     src/ptrace/init.cpp
-    src/pipe/pipe.cpp
+    src/pipe.cpp
     src/signals.cpp
 )
 
@@ -18,8 +18,8 @@ target_compile_options(trampoline PRIVATE -Wall -Wextra -Werror -Wpointer-arith
 target_link_libraries(trampoline dl rt trampoline-headers)
 
 # RPath
-set_target_properties(trampoline PROPERTIES INSTALL_RPATH "$ORIGIN/../lib/native")
+set_target_properties(trampoline PROPERTIES INSTALL_RPATH "${TRAMPOLINE_RPATH}")
-target_link_options(trampoline PRIVATE "LINKER:--disable-new-dtags")
+target_link_options(trampoline PRIVATE "LINKER:${TRAMPOLINE_EXTRA_LINK_FLAG}")
 
 # Install
 function(install_trampoline bin_dir)

native/src/main.cpp

@@ -6,8 +6,7 @@
 #include "log.h"
 #include "memory.h"
 #include "trampoline.h"
-#include "ptrace/ptrace.h"
+#include "pipe.h"
-#include "pipe/pipe.h"
 #include "signals.h"
 
 // Main
@@ -16,11 +15,8 @@ int main(__attribute__((unused)) int argc, char *argv[]) {
     if (argc < 2) {
         ERR("Invalid Arguments");
     }
-    bool use_ptrace = getenv(TRAMPOLINE_USE_PIPES_ENV) == nullptr;
     // Setup
-    if (!use_ptrace) {
+    init_pipe_common();
-        init_pipe_common();
-    }
     // Fork
     pid_t pid = fork();
     if (pid == -1) {
@@ -28,11 +24,7 @@ int main(__attribute__((unused)) int argc, char *argv[]) {
     } else if (pid == 0) {
         // Setup
         setpgid(0, 0);
-        if (use_ptrace) {
+        init_pipe_guest();
-            init_ptrace_guest();
-        } else {
-            init_pipe_guest();
-        }
         // Execute Program
         execvp(argv[1], (char *const *) &argv[1]);
         ERR("Unable To Execute Program: %s: %s", argv[1], strerror(errno));
@@ -44,11 +36,7 @@ int main(__attribute__((unused)) int argc, char *argv[]) {
         init_memory(pid);
         init_trampoline();
 
-        // Start PTrace
+        // Start Pipes
-        if (use_ptrace) {
+        init_pipe_host(pid);
-            init_ptrace_host(pid);
-        } else {
-            init_pipe_host(pid);
-        }
     }
 }

native/src/pipe.cpp

@@ -8,9 +8,9 @@
 
 #include "pipe.h"
 
-#include "../log.h"
+#include "log.h"
-#include "../trampoline.h"
+#include "trampoline.h"
-#include "../memory.h"
+#include "memory.h"
 
 // Setup Pipes
 #define PIPE_READ 0

native/src/ptrace/init.cpp

@@ -1,46 +0,0 @@
-#include <linux/seccomp.h>
-#include <linux/filter.h>
-#include <sys/prctl.h>
-#include <cstddef>
-#include <cerrno>
-#include <cstring>
-
-#include <trampoline/types.h>
-
-#include "ptrace.h"
-#include "../log.h"
-
-// Init
-void init_ptrace_host(pid_t guest_pid) {
-    // Wait For PTrace
-    safe_wait(guest_pid, nullptr);
-    // Configure PTrace
-    safe_ptrace(PTRACE_SETOPTIONS, guest_pid, nullptr, (void *) (PTRACE_O_EXITKILL | PTRACE_O_TRACESECCOMP));
-    // Start Loop
-    loop_ptrace(guest_pid);
-}
-void init_ptrace_guest() {
-    // seccomp Filter
-    sock_filter filter[] = {
-        // Load Syscall Number To Accumulator
-        BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(seccomp_data, nr)),
-        // If Syscall Does Not Match The Trampoline, Then Skip The Next Instruction
-        BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, TRAMPOLINE_SYSCALL, 0, 1),
-        // Trigger PTrace And End Filter
-        BPF_STMT(BPF_RET + BPF_K, SECCOMP_RET_TRACE),
-        // Allow Syscall And End Filter
-        BPF_STMT(BPF_RET + BPF_K, SECCOMP_RET_ALLOW)
-    };
-    sock_fprog prog = {
-        .len = (unsigned short) (sizeof(filter) / sizeof(filter[0])),
-        .filter = filter
-    };
-    // Setup PTrace
-    safe_ptrace(PTRACE_TRACEME, 0, nullptr, nullptr);
-    if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) == -1) {
-        ERR("Unable To Prepare Process For Seccomp: %s", strerror(errno));
-    }
-    if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog) == -1) {
-        ERR("Unable To Set Seccomp Filter: %s", strerror(errno));
-    }
-}

native/src/ptrace/loop.cpp

@@ -1,116 +0,0 @@
-#include <sys/wait.h>
-#include <sys/uio.h>
-#include <cstring>
-#include <cerrno>
-#include <elf.h>
-
-#ifndef __aarch64__
-#error "Unsupported Host Architecture"
-#endif
-
-#include "ptrace.h"
-#include "../log.h"
-#include "../trampoline.h"
-#include "../memory.h"
-
-// Helper Functions
-void safe_ptrace(__ptrace_request request, pid_t pid, void *addr, void *data) {
-    if (ptrace(request, pid, addr, data) == -1) {
-        ERR("PTrace Error: %s", strerror(errno));
-    }
-}
-void safe_wait(pid_t guest_pid, int *status) {
-    int real_status;
-    if (waitpid(guest_pid, &real_status, 0) == -1) {
-        ERR("Unable To Wait For Guest");
-    }
-    if (WIFEXITED(real_status)) {
-        // Process Exited
-        exit(WEXITSTATUS(real_status));
-    }
-    if (status != nullptr) {
-        *status = real_status;
-    }
-}
-static void ptrace_wait_syscall(pid_t guest_pid) {
-    while (true) {
-        safe_ptrace(PTRACE_CONT, guest_pid, nullptr, nullptr);
-        int status;
-        safe_wait(guest_pid, &status);
-        if ((status >> 8) == (SIGTRAP | (PTRACE_EVENT_SECCOMP << 8))) {
-            return;
-        }
-    }
-}
-
-// Registers
-struct arm32_pt_regs {
-    uint32_t regs[18];
-};
-static bool check_syscall(pid_t guest_pid, arm32_pt_regs *out) {
-    // Read Registers
-    arm32_pt_regs regs = {};
-    iovec io = {
-        .iov_base = &regs,
-        .iov_len = sizeof(regs)
-    };
-    safe_ptrace(PTRACE_GETREGSET, guest_pid, (void *) NT_PRSTATUS, &io);
-    if (io.iov_len != sizeof(regs)) {
-        ERR("Guest Must Be 32-Bit");
-    }
-    // Check Syscall
-    if (regs.regs[7] != TRAMPOLINE_SYSCALL) {
-        // Not Trampoline
-        return false;
-    }
-    // Block Syscall
-    int new_syscall = -1;
-    iovec syscall_io = {
-        .iov_base = &new_syscall,
-        .iov_len = sizeof(int),
-    };
-    safe_ptrace(PTRACE_SETREGSET, guest_pid, (void *) NT_ARM_SYSTEM_CALL, &syscall_io);
-    // Export Registers
-    *out = regs;
-    // Return
-    return true;
-}
-static void get_arguments(arm32_pt_regs *regs, uint32_t *arg1, uint32_t *arg2, uint32_t *arg3) {
-    *arg1 = regs->regs[0];
-    *arg2 = regs->regs[1];
-    *arg3 = regs->regs[2];
-}
-static void set_syscall_return(pid_t guest_pid, arm32_pt_regs *regs) {
-    regs->regs[0] = 0;
-    iovec io = {
-        .iov_base = regs,
-        .iov_len = sizeof(arm32_pt_regs)
-    };
-    safe_ptrace(PTRACE_SETREGSET, guest_pid, (void *) NT_PRSTATUS, &io);
-}
-
-// Main Loop
-void loop_ptrace(pid_t guest_pid) {
-    while (true) {
-        // Wait For Syscall
-        ptrace_wait_syscall(guest_pid);
-
-        // Handle Syscall
-        arm32_pt_regs regs = {};
-        bool is_trampoline = check_syscall(guest_pid, &regs);
-        if (is_trampoline) {
-            // Get Arguments
-            uint32_t id;
-            uint32_t length;
-            uint32_t args_addr;
-            get_arguments(&regs, &id, &length, &args_addr);
-            unsigned char args[MAX_TRAMPOLINE_ARGS_SIZE];
-            memory_reader(args_addr, args, length);
-            // Run Trampoline
-            const uint32_t ret = trampoline(id, args);
-            memory_writer(args_addr, &ret, sizeof(uint32_t));
-            // Set Syscall Return
-            set_syscall_return(guest_pid, &regs);
-        }
-    }
-}

native/src/ptrace/ptrace.h

@@ -1,10 +0,0 @@
-#pragma once
-
-#include <sys/types.h>
-#include <sys/ptrace.h>
-
-void safe_ptrace(__ptrace_request request, pid_t pid, void *addr, void *data);
-void safe_wait(pid_t guest_pid, int *status);
-void init_ptrace_host(pid_t guest_pid);
-void init_ptrace_guest();
-void loop_ptrace(pid_t guest_pid);

native/src/signals.cpp

@@ -2,10 +2,6 @@
 
 #include "signals.h"
 
-#include <cstdio>
-#include <cstring>
-#include <cerrno>
-
 // Signal Handlers
 static pid_t guest_pid = -1;
 static void exit_handler(__attribute__((unused)) int signal_id) {

qemu/CMakeLists.txt

@@ -36,7 +36,7 @@ ExternalProject_Add(qemu
         "--cross-prefix="
         "--cc=${CMAKE_C_COMPILER}"
         "--cxx=${CMAKE_CXX_COMPILER}"
-        "--extra-ldflags=-ldl -Wl,-rpath=$ORIGIN/../lib/native -Wl,--disable-new-dtags"
+        "--extra-ldflags=-ldl -Wl,-rpath=${TRAMPOLINE_RPATH} -Wl,${TRAMPOLINE_EXTRA_LINK_FLAG}"
         "--disable-debug-info"
         "--target-list=arm-linux-user"
         "--without-default-features"