Aristeu Rozanski d2c2b11cfa device_cgroup: check if exception removal is allowed ... [PATCH v3 1/2] device_cgroup: check if exception removal is allowed When the device cgroup hierarchy was introduced in bd2953ebbb - devcg: propagate local changes down the hierarchy a specific case was overlooked. Consider the hierarchy bellow: A default policy: ALLOW, exceptions will deny access \ B default policy: ALLOW, exceptions will deny access There's no need to verify when an new exception is added to B because in this case exceptions will deny access to further devices, which is always fine. Hierarchy in device cgroup only makes sure B won't have more access than A. But when an exception is removed (by writing devices.allow), it isn't checked if the user is in fact removing an inherited exception from A, thus giving more access to B. Example: # echo 'a' >A/devices.allow # echo 'c 1:3 rw' >A/devices.deny # echo $$ >A/B/tasks # echo >/dev/null -bash: /dev/null: Operation not permitted # echo 'c 1:3 w' >A/B/devices.allow # echo >/dev/null # This shouldn't be allowed and this patch fixes it by making sure to never allow exceptions in this case to be removed if the exception is partially or fully present on the parent. v3: missing '*' in function description v2: improved log message and formatting fixes Cc: cgroups@vger.kernel.org Cc: Li Zefan <lizefan@huawei.com> Cc: stable@vger.kernel.org Signed-off-by: Aristeu Rozanski <arozansk@redhat.com> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Tejun Heo <tj@kernel.org>		2014-05-05 11:20:12 -04:00
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apparmor	security: replace strict_strto*() with kstrto*()	2014-02-06 19:11:04 +11:00
integrity	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2014-04-12 14:49:50 -07:00
keys	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security	2014-04-03 09:26:18 -07:00
selinux	Merge branch 'locks-3.15' of git://git.samba.org/jlayton/linux	2014-04-04 14:21:20 -07:00
smack	Linux 3.13	2014-03-07 11:41:32 -05:00
tomoyo	get rid of pointless checks for NULL ->i_op	2014-04-01 23:19:16 -04:00
yama	yama: Better permission check for ptraceme	2013-03-26 13:17:58 -07:00
capability.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security	2014-04-03 09:26:18 -07:00
commoncap.c	capabilities: allow nice if we are privileged	2013-08-30 23:44:09 -07:00
device_cgroup.c	device_cgroup: check if exception removal is allowed	2014-05-05 11:20:12 -04:00
inode.c	securityfs: fix object creation races	2012-01-10 10:20:35 -05:00
Kconfig	security: select correct default LSM_MMAP_MIN_ADDR on arm on arm64	2014-02-05 14:59:14 +00:00
lsm_audit.c	audit: anchor all pid references in the initial pid namespace	2014-03-20 10:11:55 -04:00
Makefile	security: cleanup Makefiles to use standard syntax for specifying sub-directories	2014-02-17 11:08:04 +11:00
min_addr.c	mmap_min_addr check CAP_SYS_RAWIO only for write	2010-04-23 08:56:31 +10:00
security.c	vfs: add cross-rename	2014-04-01 17:08:43 +02:00