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Commit ab5a91a8 authored by Eric Paris's avatar Eric Paris Committed by James Morris
Browse files

Security: allow capable check to permit mmap or low vm space 



On a kernel with CONFIG_SECURITY but without an LSM which implements
security_file_mmap it is impossible for an application to mmap addresses
lower than mmap_min_addr.  Based on a suggestion from a developer in the
openwall community this patch adds a check for CAP_SYS_RAWIO.  It is
assumed that any process with this capability can harm the system a lot
more easily than writing some stuff on the zero page and then trying to
get the kernel to trip over itself.  It also means that programs like X
on i686 which use vm86 emulation can work even with mmap_min_addr set.

Signed-off-by: default avatarEric Paris <eparis@redhat.com>
Signed-off-by: default avatarJames Morris <jmorris@namei.org>
parent d313f948

security/dummy.c

+1 −1
Original line number Diff line number Diff line
@@ -426,7 +426,7 @@ static int dummy_file_mmap (struct file *file, unsigned long reqprot, 
			    unsigned long addr,

			    unsigned long addr_only)

{

	if (addr < mmap_min_addr)

	if ((addr < mmap_min_addr) && !capable(CAP_SYS_RAWIO))

		return -EACCES;

	return 0;

}