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authorPrarit Bhargava <prarit@redhat.com>2013-11-13 03:08:33 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2013-11-13 07:09:11 +0400
commit3d035f580699feba352f8703cced127fc203f0dd (patch)
tree9469709ea2eda88e66531edb865ab41757615a0d /drivers/char/Kconfig
parent72403b4a0fbdf433c1fe0127e49864658f6f6468 (diff)
downloadlinux-3d035f580699feba352f8703cced127fc203f0dd.tar.xz
drivers/char/hpet.c: allow user controlled mmap for user processes
The CONFIG_HPET_MMAP Kconfig option exposes the memory map of the HPET registers to userspace. The Kconfig help points out that in some cases this can be a security risk as some systems may erroneously configure the map such that additional data is exposed to userspace. This is a problem for distributions -- some users want the MMAP functionality but it comes with a significant security risk. In an effort to mitigate this risk, and due to the low number of users of the MMAP functionality, I've introduced a kernel parameter, hpet_mmap_enable, that is required in order to actually have the HPET MMAP exposed. Signed-off-by: Prarit Bhargava <prarit@redhat.com> Acked-by: Matt Wilson <msw@amazon.com> Signed-off-by: Clemens Ladisch <clemens@ladisch.de> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Tomas Winkler <tomas.winkler@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/char/Kconfig')
-rw-r--r--drivers/char/Kconfig10
1 files changed, 8 insertions, 2 deletions
diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 14219972c745..fa3243d71c76 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -522,10 +522,16 @@ config HPET_MMAP
If you say Y here, user applications will be able to mmap
the HPET registers.
+config HPET_MMAP_DEFAULT
+ bool "Enable HPET MMAP access by default"
+ default y
+ depends on HPET_MMAP
+ help
In some hardware implementations, the page containing HPET
registers may also contain other things that shouldn't be
- exposed to the user. If this applies to your hardware,
- say N here.
+ exposed to the user. This option selects the default (if
+ kernel parameter hpet_mmap is not set) user access to the
+ registers for applications that require it.
config HANGCHECK_TIMER
tristate "Hangcheck timer"