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ladybird/Kernel/Coredump.cpp
Andreas Kling da24a937f5 Kernel: Don't wrap AddressSpace's RegionTree in SpinlockProtected 
Now that AddressSpace itself is always SpinlockProtected, we don't
need to also wrap the RegionTree. Whoever has the AddressSpace locked
is free to poke around its tree.
2022-08-24 14:57:51 +02:00

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/*
* Copyright (c) 2019-2020, Jesse Buhagiar <jooster669@gmail.com>
* Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
* Copyright (c) 2020-2021, Linus Groh <linusg@serenityos.org>
* Copyright (c) 2021, Andreas Kling <klingi@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/ByteBuffer.h>
#include <AK/JsonObjectSerializer.h>
#include <Kernel/Coredump.h>
#include <Kernel/FileSystem/Custody.h>
#include <Kernel/FileSystem/OpenFileDescription.h>
#include <Kernel/FileSystem/VirtualFileSystem.h>
#include <Kernel/KLexicalPath.h>
#include <Kernel/Locking/Spinlock.h>
#include <Kernel/Memory/ScopedAddressSpaceSwitcher.h>
#include <Kernel/Process.h>
#include <Kernel/RTC.h>
#include <LibC/elf.h>
#include <LibELF/Core.h>
#define INCLUDE_USERSPACE_HEAP_MEMORY_IN_COREDUMPS 0
namespace Kernel {
[[maybe_unused]] static bool looks_like_userspace_heap_region(Memory::Region const& region)
{
return region.name().starts_with("LibJS:"sv) || region.name().starts_with("malloc:"sv);
}
ErrorOr<NonnullOwnPtr<Coredump>> Coredump::try_create(NonnullLockRefPtr<Process> process, StringView output_path)
{
if (!process->is_dumpable()) {
dbgln("Refusing to generate coredump for non-dumpable process {}", process->pid().value());
return EPERM;
}
auto description = TRY(try_create_target_file(process, output_path));
return adopt_nonnull_own_or_enomem(new (nothrow) Coredump(move(process), move(description)));
}
Coredump::Coredump(NonnullLockRefPtr<Process> process, NonnullLockRefPtr<OpenFileDescription> description)
: m_process(move(process))
, m_description(move(description))
{
m_num_program_headers = 0;
m_process->address_space().with([&](auto& space) {
for (auto& region : space->region_tree().regions()) {
#if !INCLUDE_USERSPACE_HEAP_MEMORY_IN_COREDUMPS
if (looks_like_userspace_heap_region(region))
continue;
#endif
if (region.access() == Memory::Region::Access::None)
continue;
++m_num_program_headers;
}
});
++m_num_program_headers; // +1 for NOTE segment
}
ErrorOr<NonnullLockRefPtr<OpenFileDescription>> Coredump::try_create_target_file(Process const& process, StringView output_path)
{
auto output_directory = KLexicalPath::dirname(output_path);
auto dump_directory = TRY(VirtualFileSystem::the().open_directory(Process::current().credentials(), output_directory, VirtualFileSystem::the().root_custody()));
auto dump_directory_metadata = dump_directory->inode().metadata();
if (dump_directory_metadata.uid != 0 || dump_directory_metadata.gid != 0 || dump_directory_metadata.mode != 040777) {
dbgln("Refusing to put coredump in sketchy directory '{}'", output_directory);
return EINVAL;
}
auto process_credentials = process.credentials();
return TRY(VirtualFileSystem::the().open(
Process::current().credentials(),
KLexicalPath::basename(output_path),
O_CREAT | O_WRONLY | O_EXCL,
S_IFREG, // We will enable reading from userspace when we finish generating the coredump file
*dump_directory,
UidAndGid { process_credentials->uid(), process_credentials->gid() }));
}
ErrorOr<void> Coredump::write_elf_header()
{
ElfW(Ehdr) elf_file_header;
elf_file_header.e_ident[EI_MAG0] = 0x7f;
elf_file_header.e_ident[EI_MAG1] = 'E';
elf_file_header.e_ident[EI_MAG2] = 'L';
elf_file_header.e_ident[EI_MAG3] = 'F';
#if ARCH(I386)
elf_file_header.e_ident[EI_CLASS] = ELFCLASS32;
#elif ARCH(X86_64) || ARCH(AARCH64)
elf_file_header.e_ident[EI_CLASS] = ELFCLASS64;
#else
# error Unknown architecture
#endif
elf_file_header.e_ident[EI_DATA] = ELFDATA2LSB;
elf_file_header.e_ident[EI_VERSION] = EV_CURRENT;
elf_file_header.e_ident[EI_OSABI] = 0; // ELFOSABI_NONE
elf_file_header.e_ident[EI_ABIVERSION] = 0;
elf_file_header.e_ident[EI_PAD + 1] = 0;
elf_file_header.e_ident[EI_PAD + 2] = 0;
elf_file_header.e_ident[EI_PAD + 3] = 0;
elf_file_header.e_ident[EI_PAD + 4] = 0;
elf_file_header.e_ident[EI_PAD + 5] = 0;
elf_file_header.e_ident[EI_PAD + 6] = 0;
elf_file_header.e_type = ET_CORE;
#if ARCH(I386)
elf_file_header.e_machine = EM_386;
#elif ARCH(X86_64)
elf_file_header.e_machine = EM_X86_64;
#elif ARCH(AARCH64)
elf_file_header.e_machine = EM_AARCH64;
#else
# error Unknown architecture
#endif
elf_file_header.e_version = 1;
elf_file_header.e_entry = 0;
elf_file_header.e_phoff = sizeof(ElfW(Ehdr));
elf_file_header.e_shoff = 0;
elf_file_header.e_flags = 0;
elf_file_header.e_ehsize = sizeof(ElfW(Ehdr));
elf_file_header.e_shentsize = sizeof(ElfW(Shdr));
elf_file_header.e_phentsize = sizeof(ElfW(Phdr));
elf_file_header.e_phnum = m_num_program_headers;
elf_file_header.e_shnum = 0;
elf_file_header.e_shstrndx = SHN_UNDEF;
TRY(m_description->write(UserOrKernelBuffer::for_kernel_buffer(reinterpret_cast<uint8_t*>(&elf_file_header)), sizeof(ElfW(Ehdr))));
return {};
}
ErrorOr<void> Coredump::write_program_headers(size_t notes_size)
{
size_t offset = sizeof(ElfW(Ehdr)) + m_num_program_headers * sizeof(ElfW(Phdr));
m_process->address_space().with([&](auto& space) {
for (auto& region : space->region_tree().regions()) {
#if !INCLUDE_USERSPACE_HEAP_MEMORY_IN_COREDUMPS
if (looks_like_userspace_heap_region(region))
continue;
#endif
if (region.access() == Memory::Region::Access::None)
continue;
ElfW(Phdr) phdr {};
phdr.p_type = PT_LOAD;
phdr.p_offset = offset;
phdr.p_vaddr = region.vaddr().get();
phdr.p_paddr = 0;
phdr.p_filesz = region.page_count() * PAGE_SIZE;
phdr.p_memsz = region.page_count() * PAGE_SIZE;
phdr.p_align = 0;
phdr.p_flags = region.is_readable() ? PF_R : 0;
if (region.is_writable())
phdr.p_flags |= PF_W;
if (region.is_executable())
phdr.p_flags |= PF_X;
offset += phdr.p_filesz;
[[maybe_unused]] auto rc = m_description->write(UserOrKernelBuffer::for_kernel_buffer(reinterpret_cast<uint8_t*>(&phdr)), sizeof(ElfW(Phdr)));
}
});
ElfW(Phdr) notes_pheader {};
notes_pheader.p_type = PT_NOTE;
notes_pheader.p_offset = offset;
notes_pheader.p_vaddr = 0;
notes_pheader.p_paddr = 0;
notes_pheader.p_filesz = notes_size;
notes_pheader.p_memsz = notes_size;
notes_pheader.p_align = 0;
notes_pheader.p_flags = 0;
TRY(m_description->write(UserOrKernelBuffer::for_kernel_buffer(reinterpret_cast<uint8_t*>(&notes_pheader)), sizeof(ElfW(Phdr))));
return {};
}
ErrorOr<void> Coredump::write_regions()
{
u8 zero_buffer[PAGE_SIZE] = {};
return m_process->address_space().with([&](auto& space) -> ErrorOr<void> {
for (auto& region : space->region_tree().regions()) {
VERIFY(!region.is_kernel());
#if !INCLUDE_USERSPACE_HEAP_MEMORY_IN_COREDUMPS
if (looks_like_userspace_heap_region(region))
continue;
#endif
if (region.access() == Memory::Region::Access::None)
continue;
// If we crashed in the middle of mapping in Regions, they do not have a page directory yet, and will crash on a remap() call
if (!region.is_mapped())
continue;
region.set_readable(true);
region.remap();
for (size_t i = 0; i < region.page_count(); i++) {
auto page = region.physical_page(i);
auto src_buffer = [&]() -> ErrorOr<UserOrKernelBuffer> {
if (page)
return UserOrKernelBuffer::for_user_buffer(reinterpret_cast<uint8_t*>((region.vaddr().as_ptr() + (i * PAGE_SIZE))), PAGE_SIZE);
// If the current page is not backed by a physical page, we zero it in the coredump file.
return UserOrKernelBuffer::for_kernel_buffer(zero_buffer);
}();
TRY(m_description->write(src_buffer.value(), PAGE_SIZE));
}
}
return {};
});
}
ErrorOr<void> Coredump::write_notes_segment(ReadonlyBytes notes_segment)
{
TRY(m_description->write(UserOrKernelBuffer::for_kernel_buffer(const_cast<u8*>(notes_segment.data())), notes_segment.size()));
return {};
}
ErrorOr<void> Coredump::create_notes_process_data(auto& builder) const
{
ELF::Core::ProcessInfo info {};
info.header.type = ELF::Core::NotesEntryHeader::Type::ProcessInfo;
TRY(builder.append_bytes(ReadonlyBytes { (void*)&info, sizeof(info) }));
{
auto process_obj = TRY(JsonObjectSerializer<>::try_create(builder));
TRY(process_obj.add("pid"sv, m_process->pid().value()));
TRY(process_obj.add("termination_signal"sv, m_process->termination_signal()));
TRY(process_obj.add("executable_path"sv, m_process->executable() ? TRY(m_process->executable()->try_serialize_absolute_path())->view() : ""sv));
{
auto arguments_array = TRY(process_obj.add_array("arguments"sv));
for (auto const& argument : m_process->arguments())
TRY(arguments_array.add(argument.view()));
TRY(arguments_array.finish());
}
{
auto environment_array = TRY(process_obj.add_array("environment"sv));
for (auto const& variable : m_process->environment())
TRY(environment_array.add(variable.view()));
TRY(environment_array.finish());
}
TRY(process_obj.finish());
}
TRY(builder.append('\0'));
return {};
}
ErrorOr<void> Coredump::create_notes_threads_data(auto& builder) const
{
for (auto const& thread : m_process->threads_for_coredump({})) {
ELF::Core::ThreadInfo info {};
info.header.type = ELF::Core::NotesEntryHeader::Type::ThreadInfo;
info.tid = thread.tid().value();
if (thread.current_trap())
copy_kernel_registers_into_ptrace_registers(info.regs, thread.get_register_dump_from_stack());
TRY(builder.append_bytes(ReadonlyBytes { &info, sizeof(info) }));
}
return {};
}
ErrorOr<void> Coredump::create_notes_regions_data(auto& builder) const
{
size_t region_index = 0;
return m_process->address_space().with([&](auto& space) -> ErrorOr<void> {
for (auto const& region : space->region_tree().regions()) {
#if !INCLUDE_USERSPACE_HEAP_MEMORY_IN_COREDUMPS
if (looks_like_userspace_heap_region(region))
continue;
#endif
if (region.access() == Memory::Region::Access::None)
continue;
ELF::Core::MemoryRegionInfo info {};
info.header.type = ELF::Core::NotesEntryHeader::Type::MemoryRegionInfo;
info.region_start = region.vaddr().get();
info.region_end = region.vaddr().offset(region.size()).get();
info.program_header_index = region_index++;
TRY(builder.append_bytes(ReadonlyBytes { (void*)&info, sizeof(info) }));
// NOTE: The region name *is* null-terminated, so the following is ok:
auto name = region.name();
if (name.is_empty())
TRY(builder.append('\0'));
else
TRY(builder.append(name.characters_without_null_termination(), name.length() + 1));
}
return {};
});
}
ErrorOr<void> Coredump::create_notes_metadata_data(auto& builder) const
{
ELF::Core::Metadata metadata {};
metadata.header.type = ELF::Core::NotesEntryHeader::Type::Metadata;
TRY(builder.append_bytes(ReadonlyBytes { (void*)&metadata, sizeof(metadata) }));
{
auto metadata_obj = TRY(JsonObjectSerializer<>::try_create(builder));
TRY(m_process->for_each_coredump_property([&](auto& key, auto& value) -> ErrorOr<void> {
TRY(metadata_obj.add(key.view(), value.view()));
return {};
}));
TRY(metadata_obj.finish());
}
TRY(builder.append('\0'));
return {};
}
ErrorOr<void> Coredump::create_notes_segment_data(auto& builder) const
{
TRY(create_notes_process_data(builder));
TRY(create_notes_threads_data(builder));
TRY(create_notes_regions_data(builder));
TRY(create_notes_metadata_data(builder));
ELF::Core::NotesEntryHeader null_entry {};
null_entry.type = ELF::Core::NotesEntryHeader::Type::Null;
TRY(builder.append(ReadonlyBytes { &null_entry, sizeof(null_entry) }));
return {};
}
ErrorOr<void> Coredump::write()
{
ScopedAddressSpaceSwitcher switcher(m_process);
auto builder = TRY(KBufferBuilder::try_create());
TRY(create_notes_segment_data(builder));
TRY(write_elf_header());
TRY(write_program_headers(builder.bytes().size()));
TRY(write_regions());
TRY(write_notes_segment(builder.bytes()));
return m_description->chmod(Process::current().credentials(), 0600); // Make coredump file read/writable
}
}
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