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Kernel: Add a way to specify which memory regions can make syscalls

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This patch adds sys$msyscall() which is loosely based on an OpenBSD
mechanism for preventing syscalls from non-blessed memory regions.

It works similarly to pledge and unveil, you can call it as many
times as you like, and when you're finished, you call it with a null
pointer and it will stop accepting new regions from then on.

If a syscall later happens and doesn't originate from one of the
previously blessed regions, the kernel will simply crash the process.
This commit is contained in:
Andreas Kling 2021-02-02 19:56:11 +01:00
parent d57b4128a1
commit 823186031d
10 changed files with 43 additions and 1 deletions
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2
Kernel/VM/Region.cpp
View file

@ -105,6 +105,7 @@ OwnPtr<Region> Region::clone(Process& new_owner)
region->copy_purgeable_page_ranges(*this);
region->set_mmap(m_mmap);
region->set_shared(m_shared);
region->set_syscall_region(is_syscall_region());
return region;
}
@ -127,6 +128,7 @@ OwnPtr<Region> Region::clone(Process& new_owner)
ASSERT(vmobject().is_anonymous());
clone_region->set_stack(true);
}
clone_region->set_syscall_region(is_syscall_region());
clone_region->set_mmap(m_mmap);
return clone_region;
}

4
Kernel/VM/Region.h
View file

@ -247,6 +247,9 @@ public:
RefPtr<Process> get_owner();
bool is_syscall_region() const { return m_syscall_region; }
void set_syscall_region(bool b) { m_syscall_region = b; }
private:
bool do_remap_vmobject_page_range(size_t page_index, size_t page_count);
@ -282,6 +285,7 @@ private:
bool m_stack : 1 { false };
bool m_mmap : 1 { false };
bool m_kernel : 1 { false };
bool m_syscall_region : 1 { false };
WeakPtr<Process> m_owner;
};