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Kernel/ProcFS: Allow a process directory to have a null Process pointer

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In case we are about to delete the PID directory, we clear the Process
pointer. If someone still holds a reference to the PID directory (by
opening it), we still need to delete the process, but we can't delete
the directory, so we will keep it alive, but any operation on it will
fail by propogating the error to userspace about that the Process was
deleted and therefore there's no meaning to trying to do operations on
the directory.

Fixes #8576.
This commit is contained in:
Liav A 2021-07-10 00:24:47 +03:00 • committed by Andreas Kling
parent d1028f8aed
commit bee75c1f24
4 changed files with 87 additions and 24 deletions
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73
Kernel/ProcessSpecificExposed.cpp
View file

@ -93,7 +93,10 @@ KResultOr<size_t> ProcFSProcessStacks::entries_count() const
auto parent_folder = m_process_folder.strong_ref();
if (parent_folder.is_null())
return KResult(EINVAL);
return parent_folder->m_associated_process->thread_count();
auto process = parent_folder->associated_process();
if (process.is_null())
return KResult(ESRCH);
return process->thread_count();
}
KResult ProcFSProcessStacks::traverse_as_directory(unsigned fsid, Function<bool(FileSystem::DirectoryEntryView const&)> callback) const
@ -105,7 +108,9 @@ KResult ProcFSProcessStacks::traverse_as_directory(unsigned fsid, Function<bool(
callback({ ".", { fsid, component_index() }, 0 });
callback({ "..", { fsid, parent_folder->component_index() }, 0 });
auto process = parent_folder->m_associated_process;
auto process = parent_folder->associated_process();
if (process.is_null())
return KResult(ESRCH);
process->for_each_thread([&](const Thread& thread) {
int tid = thread.tid().value();
InodeIdentifier identifier = { fsid, thread.global_procfs_inode_index() };
@ -120,7 +125,9 @@ RefPtr<ProcFSExposedComponent> ProcFSProcessStacks::lookup(StringView name)
auto parent_folder = m_process_folder.strong_ref();
if (parent_folder.is_null())
return nullptr;
auto process = parent_folder->m_associated_process;
auto process = parent_folder->associated_process();
if (process.is_null())
return nullptr;
RefPtr<ProcFSThreadStack> procfd_stack;
// FIXME: Try to exit the loop earlier
process->for_each_thread([&](const Thread& thread) {
@ -195,7 +202,10 @@ KResultOr<size_t> ProcFSProcessFileDescriptions::entries_count() const
auto parent_folder = m_process_folder.strong_ref();
if (parent_folder.is_null())
return KResult(EINVAL);
return parent_folder->m_associated_process->fds().open_count();
auto process = parent_folder->associated_process();
if (process.is_null())
return KResult(ESRCH);
return process->fds().open_count();
}
KResult ProcFSProcessFileDescriptions::traverse_as_directory(unsigned fsid, Function<bool(FileSystem::DirectoryEntryView const&)> callback) const
{
@ -206,7 +216,9 @@ KResult ProcFSProcessFileDescriptions::traverse_as_directory(unsigned fsid, Func
callback({ ".", { fsid, component_index() }, 0 });
callback({ "..", { fsid, parent_folder->component_index() }, 0 });
auto process = parent_folder->m_associated_process;
auto process = parent_folder->associated_process();
if (process.is_null())
return KResult(ESRCH);
size_t count = 0;
process->fds().enumerate([&](auto& file_description_metadata) {
if (!file_description_metadata.is_valid()) {
@ -225,7 +237,9 @@ RefPtr<ProcFSExposedComponent> ProcFSProcessFileDescriptions::lookup(StringView
auto parent_folder = m_process_folder.strong_ref();
if (parent_folder.is_null())
return nullptr;
auto process = parent_folder->m_associated_process;
auto process = parent_folder->associated_process();
if (process.is_null())
return nullptr;
RefPtr<ProcFSProcessFileDescription> procfd_fd;
// FIXME: Try to exit the loop earlier
size_t count = 0;
@ -259,7 +273,9 @@ private:
auto parent_folder = m_parent_folder.strong_ref();
if (parent_folder.is_null())
return false;
auto process = parent_folder->m_associated_process;
auto process = parent_folder->associated_process();
if (process.is_null())
return false;
JsonObjectSerializer obj { builder };
#define __ENUMERATE_PLEDGE_PROMISE(x) \
if (process->has_promised(Pledge::x)) { \
@ -295,8 +311,11 @@ private:
auto parent_folder = m_parent_folder.strong_ref();
if (parent_folder.is_null())
return false;
auto process = parent_folder->associated_process();
if (process.is_null())
return false;
JsonArraySerializer array { builder };
for (auto& unveiled_path : parent_folder->m_associated_process->unveiled_paths()) {
for (auto& unveiled_path : process->unveiled_paths()) {
if (!unveiled_path.was_explicitly_unveiled())
continue;
auto obj = array.add_object();
@ -337,7 +356,9 @@ private:
auto parent_folder = m_parent_folder.strong_ref();
if (parent_folder.is_null())
return false;
auto process = parent_folder->m_associated_process;
auto process = parent_folder->associated_process();
if (process.is_null())
return false;
if (!process->perf_events()) {
dbgln("ProcFS: No perf events for {}", process->pid());
return false;
@ -364,7 +385,9 @@ private:
if (parent_folder.is_null())
return false;
JsonArraySerializer array { builder };
auto process = parent_folder->m_associated_process;
auto process = parent_folder->associated_process();
if (process.is_null())
return false;
if (process->fds().open_count() == 0) {
array.finish();
return true;
@ -414,7 +437,10 @@ private:
auto parent_folder = m_parent_process_directory.strong_ref();
if (parent_folder.is_null())
return false;
builder.append_bytes(parent_folder->m_associated_process->root_directory_relative_to_global_root().absolute_path().to_byte_buffer());
auto process = parent_folder->associated_process();
if (process.is_null())
return false;
builder.append_bytes(process->root_directory_relative_to_global_root().absolute_path().to_byte_buffer());
return true;
}
WeakPtr<ProcFSProcessDirectory> m_parent_process_directory;
@ -437,7 +463,9 @@ private:
auto parent_folder = m_parent_folder.strong_ref();
if (parent_folder.is_null())
return false;
auto process = parent_folder->m_associated_process;
auto process = parent_folder->associated_process();
if (process.is_null())
return false;
JsonArraySerializer array { builder };
{
ScopedSpinLock lock(process->space().get_lock());
@ -500,7 +528,10 @@ private:
auto parent_folder = m_parent_process_directory.strong_ref();
if (parent_folder.is_null())
return false;
builder.append_bytes(parent_folder->m_associated_process->current_directory().absolute_path().bytes());
auto process = parent_folder->associated_process();
if (process.is_null())
return false;
builder.append_bytes(process->current_directory().absolute_path().bytes());
return true;
}
@ -519,7 +550,10 @@ public:
auto parent_folder = m_parent_process_directory.strong_ref();
if (parent_folder.is_null())
return false;
if (!parent_folder->m_associated_process->executable())
auto process = parent_folder->associated_process();
if (process.is_null())
return false;
if (!process->executable())
return 0;
return ProcFSExposedComponent::required_mode();
}
@ -535,7 +569,10 @@ private:
auto parent_folder = m_parent_process_directory.strong_ref();
if (parent_folder.is_null())
return false;
auto* custody = parent_folder->m_associated_process->executable();
auto process = parent_folder->associated_process();
if (process.is_null())
return false;
auto* custody = process->executable();
if (!custody)
return false;
builder.append(custody->absolute_path().bytes());
@ -582,6 +619,12 @@ NonnullRefPtr<ProcFSProcessDirectory> ProcFSProcessDirectory::create(const Proce
return adopt_ref_if_nonnull(new (nothrow) ProcFSProcessDirectory(process)).release_nonnull();
}
void ProcFSProcessDirectory::prepare_for_deletion()
{
ProcFSExposedDirectory::prepare_for_deletion();
m_associated_process.clear();
}
ProcFSProcessDirectory::ProcFSProcessDirectory(const Process& process)
: ProcFSExposedDirectory(String::formatted("{:d}", process.pid().value()), ProcFSComponentRegistry::the().root_folder())
, m_associated_process(process)