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authorSerge E. Hallyn <serge@hallyn.com>2011-03-23 16:43:17 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-03-23 19:47:02 -0700
commit3486740a4f32a6a466f5ac931654d154790ba648 (patch)
treeac5d968a66057fa84933b8f89fd3e916270dffed /security/selinux
parent59607db367c57f515183cb203642291bb14d9c40 (diff)
userns: security: make capabilities relative to the user namespace
- Introduce ns_capable to test for a capability in a non-default user namespace. - Teach cap_capable to handle capabilities in a non-default user namespace. The motivation is to get to the unprivileged creation of new namespaces. It looks like this gets us 90% of the way there, with only potential uid confusion issues left. I still need to handle getting all caps after creation but otherwise I think I have a good starter patch that achieves all of your goals. Changelog: 11/05/2010: [serge] add apparmor 12/14/2010: [serge] fix capabilities to created user namespaces Without this, if user serge creates a user_ns, he won't have capabilities to the user_ns he created. THis is because we were first checking whether his effective caps had the caps he needed and returning -EPERM if not, and THEN checking whether he was the creator. Reverse those checks. 12/16/2010: [serge] security_real_capable needs ns argument in !security case 01/11/2011: [serge] add task_ns_capable helper 01/11/2011: [serge] add nsown_capable() helper per Bastian Blank suggestion 02/16/2011: [serge] fix a logic bug: the root user is always creator of init_user_ns, but should not always have capabilities to it! Fix the check in cap_capable(). 02/21/2011: Add the required user_ns parameter to security_capable, fixing a compile failure. 02/23/2011: Convert some macros to functions as per akpm comments. Some couldn't be converted because we can't easily forward-declare them (they are inline if !SECURITY, extern if SECURITY). Add a current_user_ns function so we can use it in capability.h without #including cred.h. Move all forward declarations together to the top of the #ifdef __KERNEL__ section, and use kernel-doc format. 02/23/2011: Per dhowells, clean up comment in cap_capable(). 02/23/2011: Per akpm, remove unreachable 'return -EPERM' in cap_capable. (Original written and signed off by Eric; latest, modified version acked by him) [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: export current_user_ns() for ecryptfs] [serge.hallyn@canonical.com: remove unneeded extra argument in selinux's task_has_capability] Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Acked-by: Daniel Lezcano <daniel.lezcano@free.fr> Acked-by: David Howells <dhowells@redhat.com> Cc: James Morris <jmorris@namei.org> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'security/selinux')
-rw-r--r--security/selinux/hooks.c13
1 files changed, 8 insertions, 5 deletions
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 6475e1f0223e..c67f863d3546 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -79,6 +79,7 @@
#include <linux/mutex.h>
#include <linux/posix-timers.h>
#include <linux/syslog.h>
+#include <linux/user_namespace.h>
#include "avc.h"
#include "objsec.h"
@@ -1846,11 +1847,11 @@ static int selinux_capset(struct cred *new, const struct cred *old,
*/
static int selinux_capable(struct task_struct *tsk, const struct cred *cred,
- int cap, int audit)
+ struct user_namespace *ns, int cap, int audit)
{
int rc;
- rc = cap_capable(tsk, cred, cap, audit);
+ rc = cap_capable(tsk, cred, ns, cap, audit);
if (rc)
return rc;
@@ -1931,7 +1932,8 @@ static int selinux_vm_enough_memory(struct mm_struct *mm, long pages)
{
int rc, cap_sys_admin = 0;
- rc = selinux_capable(current, current_cred(), CAP_SYS_ADMIN,
+ rc = selinux_capable(current, current_cred(),
+ &init_user_ns, CAP_SYS_ADMIN,
SECURITY_CAP_NOAUDIT);
if (rc == 0)
cap_sys_admin = 1;
@@ -2834,7 +2836,8 @@ static int selinux_inode_getsecurity(const struct inode *inode, const char *name
* and lack of permission just means that we fall back to the
* in-core context value, not a denial.
*/
- error = selinux_capable(current, current_cred(), CAP_MAC_ADMIN,
+ error = selinux_capable(current, current_cred(),
+ &init_user_ns, CAP_MAC_ADMIN,
SECURITY_CAP_NOAUDIT);
if (!error)
error = security_sid_to_context_force(isec->sid, &context,
@@ -2968,7 +2971,7 @@ static int selinux_file_ioctl(struct file *file, unsigned int cmd,
case KDSKBENT:
case KDSKBSENT:
error = task_has_capability(current, cred, CAP_SYS_TTY_CONFIG,
- SECURITY_CAP_AUDIT);
+ SECURITY_CAP_AUDIT);
break;
/* default case assumes that the command will go