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Check old page protections

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This commit is contained in:
Jeremy Rifkin 2024-08-17 19:41:24 -05:00
parent 85647b8334
commit a44cc5239c
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GPG Key ID: 19AA8270105E8EB4
1 changed files with 100 additions and 8 deletions
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108
src/from_current.cpp
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@ -12,11 +12,17 @@
#ifndef _MSC_VER
#include <array>
#include <string.h>
#ifndef _WIN32
#if IS_WINDOWS
#include <windows.h>
#else
#include <sys/mman.h>
#include <unistd.h>
#else
#include <windows.h>
#if IS_APPLE
#include <mach/mach.h>
#else
#include <fstream>
#include <iomanip>
#endif
#endif
#endif
@ -50,7 +56,7 @@ namespace cpptrace {
}
constexpr auto memory_readonly = PAGE_READONLY;
constexpr auto memory_readwrite = PAGE_READWRITE;
void mprotect_page(void* page, int page_size, int protections) {
int mprotect_page_and_return_old_protections(void* page, int page_size, int protections) {
DWORD old_protections;
if(!VirtualProtect(page, page_size, protections, &old_protections)) {
throw std::runtime_error(
@ -60,6 +66,10 @@ namespace cpptrace {
)
);
}
return old_protections;
}
void mprotect_page(void* page, int page_size, int protections) {
mprotect_page_and_return_old_protections(page, page_size, protections);
}
void* allocate_page(int page_size) {
auto page = VirtualAlloc(nullptr, page_size, MEM_COMMIT | MEM_RESERVE, memory_readwrite);
@ -79,11 +89,90 @@ namespace cpptrace {
}
constexpr auto memory_readonly = PROT_READ;
constexpr auto memory_readwrite = PROT_READ | PROT_WRITE;
#if IS_APPLE
int get_page_protections(void* page) {
// https://stackoverflow.com/a/12627784/15675011
vm_size_t vmsize;
vm_address_t address = (vm_address_t)page;
vm_region_basic_info_data_t info;
mach_msg_type_number_t info_count = VM_REGION_BASIC_INFO_COUNT;
memory_object_name_t object;
kern_return_t status = vm_region(
mach_task_self(),
&address,
&vmsize,
VM_REGION_BASIC_INFO,
(vm_region_info_t)&info,
&info_count,
&object
);
if(status == KERN_INVALID_ADDRESS) {
throw std::runtime_error("vm_region failed with KERN_INVALID_ADDRESS");
}
int perms = 0;
if(info.protection & VM_PROT_READ) {
perms |= PROT_READ;
}
if(info.protection & VM_PROT_WRITE) {
perms |= PROT_WRITE;
}
if(info.protection & VM_PROT_EXECUTE) {
perms |= PROT_EXEC;
}
return perms;
}
#else
int get_page_protections(void* page) {
auto page_addr = reinterpret_cast<uintptr_t>(page);
std::ifstream stream("/proc/self/maps");
stream>>std::hex;
while(!stream.eof()) {
uintptr_t start;
uintptr_t stop;
stream>>start;
stream.ignore(1);
stream>>stop;
if(stream.eof()) {
break;
}
if(stream.fail()) {
throw std::runtime_error("Failure reading /proc/self/maps");
}
if(page_addr >= start && page_addr < stop) {
stream.ignore(1);
char r, w, x;
stream>>r>>w>>x;
if(stream.fail() || stream.eof()) {
throw std::runtime_error("Failure reading /proc/self/maps");
}
int perms = 0;
if(r == 'r') {
perms |= PROT_READ;
}
if(w == 'w') {
perms |= PROT_WRITE;
}
if(x == 'x') {
perms |= PROT_EXEC;
}
std::cerr<<"--parsed: "<<std::hex<<start<<" "<<stop<<" "<<r<<w<<x<<std::endl;
return perms;
}
stream.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
}
throw std::runtime_error("Failed to find mapping with page in /proc/self/maps");
}
#endif
void mprotect_page(void* page, int page_size, int protections) {
if(mprotect(page, page_size, protections) != 0) {
throw std::runtime_error(microfmt::format("mprotect call failed: {}", strerror(errno)));
}
}
int mprotect_page_and_return_old_protections(void* page, int page_size, int protections) {
auto old_protections = get_page_protections(page);
mprotect_page(page, page_size, protections);
return old_protections;
}
void* allocate_page(int page_size) {
auto page = mmap(nullptr, page_size, memory_readwrite, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
if(page == MAP_FAILED) {
@ -133,7 +222,7 @@ namespace cpptrace {
// https://github.com/llvm/llvm-project/blob/648f4d0658ab00cf1e95330c8811aaea9481a274/libcxx/include/typeinfo
// https://github.com/llvm/llvm-project/blob/648f4d0658ab00cf1e95330c8811aaea9481a274/libcxxabi/src/private_typeinfo.h
// probably 4096 but out of an abundance of caution
// shouldn't be anything other than 4096 but out of an abundance of caution
auto page_size = get_page_size();
if(page_size <= 0 && (page_size & (page_size - 1)) != 0) {
throw std::runtime_error(
@ -158,10 +247,13 @@ namespace cpptrace {
if(type_info_addr - page_addr + sizeof(void*) > static_cast<unsigned>(page_size)) {
throw std::runtime_error("pointer crosses page boundaries");
}
// TODO: Check perms of page
mprotect_page(reinterpret_cast<void*>(page_addr), page_size, memory_readwrite);
auto old_protections = mprotect_page_and_return_old_protections(
reinterpret_cast<void*>(page_addr),
page_size,
memory_readwrite
);
*static_cast<void**>(type_info_pointer) = static_cast<void*>(new_vtable + 2);
mprotect_page(reinterpret_cast<void*>(page_addr), page_size, memory_readonly);
mprotect_page(reinterpret_cast<void*>(page_addr), page_size, old_protections);
}
void do_prepare_unwind_interceptor() {