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kernel: Enforce W^X protection for kernel areas.

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We already adhere to this in the kernel itself as well as all
in-tree drivers, so we might as well actually enforce it now.
This commit is contained in:
Augustin Cavalier
2018-12-09 15:19:08 -05:00
parent f232d9d22c
commit cb0977326d
1 changed files with 5 additions and 0 deletions
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src/system/kernel/vm/vm.cpp
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@@ -4914,6 +4914,7 @@ vm_set_area_memory_type(area_id id, phys_addr_t physicalBase, uint32 type)
/*! This function enforces some protection properties: /*! This function enforces some protection properties:
- kernel areas must be W^X
- if B_WRITE_AREA is set, B_KERNEL_WRITE_AREA is set as well - if B_WRITE_AREA is set, B_KERNEL_WRITE_AREA is set as well
- if only B_READ_AREA has been set, B_KERNEL_READ_AREA is also set - if only B_READ_AREA has been set, B_KERNEL_READ_AREA is also set
- if no protection is specified, it defaults to B_KERNEL_READ_AREA - if no protection is specified, it defaults to B_KERNEL_READ_AREA
@@ -4922,6 +4923,10 @@ vm_set_area_memory_type(area_id id, phys_addr_t physicalBase, uint32 type)
static void static void
fix_protection(uint32* protection) fix_protection(uint32* protection)
{ {
if ((*protection & B_KERNEL_WRITE_AREA) != 0
&& (*protection & B_KERNEL_EXECUTE_AREA) != 0)
panic("kernel areas cannot be both writable and executable!");
if ((*protection & B_KERNEL_PROTECTION) == 0) { if ((*protection & B_KERNEL_PROTECTION) == 0) {
if ((*protection & B_USER_PROTECTION) == 0 if ((*protection & B_USER_PROTECTION) == 0
|| (*protection & B_WRITE_AREA) != 0) || (*protection & B_WRITE_AREA) != 0)