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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: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
This commit is contained in:
Eric Paris 2007-11-26 18:47:46 -05:00 committed by James Morris
parent d313f94830
commit ab5a91a836
1 changed files with 1 additions and 1 deletions
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2
security/dummy.c
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@ -426,7 +426,7 @@ static int dummy_file_mmap (struct file *file, unsigned long reqprot,
unsigned long addr, unsigned long addr,
unsigned long addr_only) unsigned long addr_only)
{ {
if (addr < mmap_min_addr) if ((addr < mmap_min_addr) && !capable(CAP_SYS_RAWIO))
return -EACCES; return -EACCES;
return 0; return 0;
} }