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Kernel: Remove "has made executable exception for dynamic loader" flag

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As Idan pointed out, this flag is actually not needed, since we don't
allow transitioning from previously-executable to writable anyway.
This commit is contained in:
Andreas Kling 2021-01-30 10:06:52 +01:00
parent 5b37c0a71a
commit e55ef70e5e
2 changed files with 4 additions and 32 deletions
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26
Kernel/Syscalls/mmap.cpp
View file

@ -46,10 +46,6 @@ static bool should_make_executable_exception_for_dynamic_loader(bool make_readab
// The exception is only made if all the following criteria is fulfilled:
// This exception has not been made for the same region already
if (region.has_made_executable_exception_for_dynamic_loader())
return false;
// The region must be RW
if (!(region.is_readable() && region.is_writable() && !region.is_executable()))
return false;
@ -84,11 +80,8 @@ static bool should_make_executable_exception_for_dynamic_loader(bool make_readab
return true;
}
static bool validate_mmap_prot(int prot, bool map_stack, bool map_anonymous, const Region* region = nullptr, bool* is_making_executable_exception_for_dynamic_loader = nullptr)
static bool validate_mmap_prot(int prot, bool map_stack, bool map_anonymous, const Region* region = nullptr)
{
if (is_making_executable_exception_for_dynamic_loader)
*is_making_executable_exception_for_dynamic_loader = false;
bool make_readable = prot & PROT_READ;
bool make_writable = prot & PROT_WRITE;
bool make_executable = prot & PROT_EXEC;
@ -111,11 +104,8 @@ static bool validate_mmap_prot(int prot, bool map_stack, bool map_anonymous, con
return false;
if (make_executable && region->has_been_writable()) {
if (should_make_executable_exception_for_dynamic_loader(make_readable, make_writable, make_executable, *region)) {
ASSERT(is_making_executable_exception_for_dynamic_loader);
*is_making_executable_exception_for_dynamic_loader = true;
if (should_make_executable_exception_for_dynamic_loader(make_readable, make_writable, make_executable, *region))
return true;
}
return false;
}
@ -293,8 +283,7 @@ int Process::sys$mprotect(void* addr, size_t size, int prot)
if (auto* whole_region = find_region_from_range(range_to_mprotect)) {
if (!whole_region->is_mmap())
return -EPERM;
bool is_making_executable_exception_for_dynamic_loader = false;
if (!validate_mmap_prot(prot, whole_region->is_stack(), whole_region->vmobject().is_anonymous(), whole_region, &is_making_executable_exception_for_dynamic_loader))
if (!validate_mmap_prot(prot, whole_region->is_stack(), whole_region->vmobject().is_anonymous(), whole_region))
return -EINVAL;
if (whole_region->access() == prot_to_region_access_flags(prot))
return 0;
@ -306,9 +295,6 @@ int Process::sys$mprotect(void* addr, size_t size, int prot)
whole_region->set_writable(prot & PROT_WRITE);
whole_region->set_executable(prot & PROT_EXEC);
if (is_making_executable_exception_for_dynamic_loader)
whole_region->set_has_made_executable_exception_for_dynamic_loader();
whole_region->remap();
return 0;
}
@ -317,8 +303,7 @@ int Process::sys$mprotect(void* addr, size_t size, int prot)
if (auto* old_region = find_region_containing(range_to_mprotect)) {
if (!old_region->is_mmap())
return -EPERM;
bool is_making_executable_exception_for_dynamic_loader = false;
if (!validate_mmap_prot(prot, old_region->is_stack(), old_region->vmobject().is_anonymous(), old_region, &is_making_executable_exception_for_dynamic_loader))
if (!validate_mmap_prot(prot, old_region->is_stack(), old_region->vmobject().is_anonymous(), old_region))
return -EINVAL;
if (old_region->access() == prot_to_region_access_flags(prot))
return 0;
@ -337,9 +322,6 @@ int Process::sys$mprotect(void* addr, size_t size, int prot)
new_region.set_writable(prot & PROT_WRITE);
new_region.set_executable(prot & PROT_EXEC);
if (is_making_executable_exception_for_dynamic_loader)
new_region.set_has_made_executable_exception_for_dynamic_loader();
// Unmap the old region here, specifying that we *don't* want the VM deallocated.
old_region->unmap(Region::ShouldDeallocateVirtualMemoryRange::No);
deallocate_region(*old_region);

10
Kernel/VM/Region.h
View file

@ -50,8 +50,6 @@ class Region final
MAKE_SLAB_ALLOCATED(Region)
public:
// 76543210
// eXWR xwr
enum Access : u8 {
Read = 1,
Write = 2,
@ -59,7 +57,6 @@ public:
HasBeenReadable = 16,
HasBeenWritable = 32,
HasBeenExecutable = 64,
HasMadeExecutableExceptionForDynamicLoader = 128,
};
static NonnullOwnPtr<Region> create_user_accessible(Process*, const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const StringView& name, u8 access, bool cacheable, bool shared);
@ -78,13 +75,6 @@ public:
bool has_been_writable() const { return m_access & Access::HasBeenWritable; }
bool has_been_executable() const { return m_access & Access::HasBeenExecutable; }
bool has_made_executable_exception_for_dynamic_loader() const { return m_access & Access::HasMadeExecutableExceptionForDynamicLoader; }
void set_has_made_executable_exception_for_dynamic_loader()
{
ASSERT(!has_made_executable_exception_for_dynamic_loader());
m_access |= Access::HasMadeExecutableExceptionForDynamicLoader;
}
bool is_cacheable() const { return m_cacheable; }
const String& name() const { return m_name; }
unsigned access() const { return m_access; }