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Kernel: Work using copies of specific region data during a coredump

This limits our interaction with the "real" region tree (and therefore
its lock) to the time where we actually read from the user address
space.
This commit is contained in:
Tim Schumacher 2022-08-23 20:51:42 +02:00 committed by Andreas Kling
parent 066c5acee1
commit 32a03cffeb
2 changed files with 148 additions and 75 deletions

View file

@ -25,9 +25,23 @@
namespace Kernel {
[[maybe_unused]] static bool looks_like_userspace_heap_region(Memory::Region const& region)
bool Coredump::FlatRegionData::looks_like_userspace_heap_region() const
{
return region.name().starts_with("LibJS:"sv) || region.name().starts_with("malloc:"sv);
return name().starts_with("LibJS:"sv) || name().starts_with("malloc:"sv);
}
bool Coredump::FlatRegionData::is_consistent_with_region(Memory::Region const& region) const
{
if (m_access != region.access())
return false;
if (m_page_count != region.page_count() || m_size != region.size())
return false;
if (m_vaddr != region.vaddr())
return false;
return true;
}
ErrorOr<NonnullOwnPtr<Coredump>> Coredump::try_create(NonnullLockRefPtr<Process> process, StringView output_path)
@ -37,27 +51,37 @@ ErrorOr<NonnullOwnPtr<Coredump>> Coredump::try_create(NonnullLockRefPtr<Process>
return EPERM;
}
Vector<FlatRegionData> regions;
size_t number_of_regions = process->address_space().with([](auto& space) {
return space->region_tree().regions().size();
});
TRY(regions.try_ensure_capacity(number_of_regions));
TRY(process->address_space().with([&](auto& space) -> ErrorOr<void> {
for (auto& region : space->region_tree().regions())
TRY(regions.try_empend(region, TRY(KString::try_create(region.name()))));
return {};
}));
auto description = TRY(try_create_target_file(process, output_path));
return adopt_nonnull_own_or_enomem(new (nothrow) Coredump(move(process), move(description)));
return adopt_nonnull_own_or_enomem(new (nothrow) Coredump(move(process), move(description), move(regions)));
}
Coredump::Coredump(NonnullLockRefPtr<Process> process, NonnullLockRefPtr<OpenFileDescription> description)
Coredump::Coredump(NonnullLockRefPtr<Process> process, NonnullLockRefPtr<OpenFileDescription> description, Vector<FlatRegionData> regions)
: m_process(move(process))
, m_description(move(description))
, m_regions(move(regions))
{
m_num_program_headers = 0;
m_process->address_space().with([&](auto& space) {
for (auto& region : space->region_tree().regions()) {
for (auto& region : m_regions) {
#if !INCLUDE_USERSPACE_HEAP_MEMORY_IN_COREDUMPS
if (looks_like_userspace_heap_region(region))
continue;
if (region.looks_like_userspace_heap_region())
continue;
#endif
if (region.access() == Memory::Region::Access::None)
continue;
++m_num_program_headers;
}
});
if (region.access() == Memory::Region::Access::None)
continue;
++m_num_program_headers;
}
++m_num_program_headers; // +1 for NOTE segment
}
@ -135,39 +159,36 @@ ErrorOr<void> Coredump::write_elf_header()
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()) {
for (auto& region : m_regions) {
#if !INCLUDE_USERSPACE_HEAP_MEMORY_IN_COREDUMPS
if (looks_like_userspace_heap_region(region))
continue;
if (region.looks_like_userspace_heap_region())
continue;
#endif
if (region.access() == Memory::Region::Access::None)
continue;
if (region.access() == Memory::Region::Access::None)
continue;
ElfW(Phdr) phdr {};
ElfW(Phdr) phdr {};
phdr.p_type = PT_LOAD;
phdr.p_offset = offset;
phdr.p_vaddr = region.vaddr().get();
phdr.p_paddr = 0;
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_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;
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;
offset += phdr.p_filesz;
[[maybe_unused]] auto rc = m_description->write(UserOrKernelBuffer::for_kernel_buffer(reinterpret_cast<uint8_t*>(&phdr)), sizeof(ElfW(Phdr)));
}
});
[[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;
@ -188,27 +209,35 @@ 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());
for (auto& region : m_regions) {
VERIFY(!region.is_kernel());
#if !INCLUDE_USERSPACE_HEAP_MEMORY_IN_COREDUMPS
if (looks_like_userspace_heap_region(region))
continue;
if (region.looks_like_userspace_heap_region())
continue;
#endif
if (region.access() == Memory::Region::Access::None)
continue;
if (region.access() == Memory::Region::Access::None)
continue;
TRY(m_process->address_space().with([&](auto& space) -> ErrorOr<void> {
auto* real_region = space->region_tree().regions().find(region.vaddr().get());
if (!real_region)
return Error::from_string_view("Failed to find matching region in the process"sv);
if (!region.is_consistent_with_region(*real_region))
return Error::from_string_view("Found region does not match stored metadata"sv);
// 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;
if (!real_region->is_mapped())
return {};
region.set_readable(true);
region.remap();
real_region->set_readable(true);
real_region->remap();
for (size_t i = 0; i < region.page_count(); i++) {
auto page = region.physical_page(i);
auto page = real_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);
@ -217,9 +246,12 @@ ErrorOr<void> Coredump::write_regions()
}();
TRY(m_description->write(src_buffer.value(), PAGE_SIZE));
}
}
return {};
});
return {};
}));
}
return {};
}
ErrorOr<void> Coredump::write_notes_segment(ReadonlyBytes notes_segment)
@ -279,35 +311,33 @@ ErrorOr<void> Coredump::create_notes_threads_data(auto& builder) const
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()) {
for (auto const& region : m_regions) {
#if !INCLUDE_USERSPACE_HEAP_MEMORY_IN_COREDUMPS
if (looks_like_userspace_heap_region(region))
continue;
if (region.looks_like_userspace_heap_region())
continue;
#endif
if (region.access() == Memory::Region::Access::None)
continue;
if (region.access() == Memory::Region::Access::None)
continue;
ELF::Core::MemoryRegionInfo info {};
info.header.type = ELF::Core::NotesEntryHeader::Type::MemoryRegionInfo;
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++;
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) }));
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 {};
});
// 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