[KernelCache] Set segment flags based on how XNU initially maps them#7519
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[KernelCache] Set segment flags based on how XNU initially maps them#7519
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… them XNU maps kernel cache segments in with different permissions than the load commands indicate. For instance, `__DATA_CONST` is initially mapped as read-write before later being re-mapped as read-only. Treating it as read-only results in analysis falsely assuming that global variables cannot change. To work around this we maintain a mapping from segment name to initial permissions (i.e., most lax permissions) and favor them over permissions derived from the segment load command. Section semantics are also derived from the segment's permissions when the segment is present in the mapping. The mapping is based on the initial permissions established by `arm_vm_prot_init` within the XNU source.
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…y maps them This was done for kernel cache in #7519, and is now being extended to Mach-O images that appear to be XNU kernels (that is, they contain `__KLD` segments). This improves the experience when opening kernels from the macOS Kernel Debug Kit.
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…y maps them This was done for kernel cache in #7519, and is now being extended to Mach-O images that appear to be XNU kernels (that is, they contain `__KLD` segments). This improves the experience when opening kernels from the macOS Kernel Debug Kit.
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XNU maps kernel cache segments in with different permissions than the load commands indicate. For instance,
__DATA_CONSTis initially mapped as read-write before later being re-mapped as read-only. Treating it as read-only results in analysis falsely assuming that global variables cannot change.To work around this we maintain a mapping from segment name to initial permissions (i.e., most lax permissions) and favor them over permissions derived from the segment load command. Section semantics are also derived from the segment's permissions when the segment is present in the mapping.
The mapping is based on the initial permissions established by
arm_vm_prot_initwithin the XNU source.Related to #6718.