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Kernel: Guard Process "protected data" with a spinlock

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This ensures that both mutable and immutable access to the protected
data of a process is serialized.

Note that there may still be multiple TOCTOU issues around this, as we
have a bunch of convenience accessors that make it easy to introduce
them. We'll need to audit those as well.
This commit is contained in:
Andreas Kling 2022-08-21 12:18:26 +02:00
parent 728c3fbd14
commit 8ed06ad814
11 changed files with 348 additions and 300 deletions
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9
Kernel/Syscalls/umask.cpp
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@ -12,10 +12,11 @@ ErrorOr<FlatPtr> Process::sys$umask(mode_t mask)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
TRY(require_promise(Pledge::stdio));
auto old_mask = m_protected_values.umask;
ProtectedDataMutationScope scope { *this };
m_protected_values.umask = mask & 0777;
return old_mask;
return with_mutable_protected_data([&](auto& protected_data) -> ErrorOr<FlatPtr> {
auto old_mask = protected_data.umask;
protected_data.umask = mask & 0777;
return old_mask;
});
}
}