kernel/vm: restrict permission changes on shared file-mapped areas

a protection_max attribute is added in VMArea.
a read-only opened file already can't be mapped shared read-write at the moment,
but can later be changed to read-write with mprotect() or set_area_protection().
When creating the VMArea, the actual maximum protection is stored in the area,
so that it can be checked when needed.
this fixes a VM TODO.

Change-Id: I33b144c192034eeb059f1dede5dbef5af947280d
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3804
Reviewed-by: Adrien Destugues <[email protected]>

This commit is contained in:

Jérôme Duval

2021-03-23 17:40:31 +00:00

committed by

Adrien Destugues

parent 99806fe3d6

commit 45872f7f9c

3 changed files with 44 additions and 20 deletions

									
										headers/private/kernel/vm/VMArea.h
									
		+1
		
												View File
												
				@@ -100,6 +100,7 @@ public:

					area_id					id;

					char					name[B_OS_NAME_LENGTH];

					uint32					protection;

					uint32					protection_max;

					uint16					wiring;

				private: