userns: user namespaces: convert several capable() calls

CAP_IPC_OWNER and CAP_IPC_LOCK can be checked against current_user_ns(),
because the resource comes from current's own ipc namespace.

setuid/setgid are to uids in own namespace, so again checks can be against
current_user_ns().

Changelog:
	Jan 11: Use task_ns_capable() in place of sched_capable().
	Jan 11: Use nsown_capable() as suggested by Bastian Blank.
	Jan 11: Clarify (hopefully) some logic in futex and sched.c
	Feb 15: use ns_capable for ipc, not nsown_capable
	Feb 23: let copy_ipcs handle setting ipc_ns->user_ns
	Feb 23: pass ns down rather than taking it from current

[akpm@linux-foundation.org: coding-style fixes]
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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 16 insertions, 10 deletions

diff --git a/ipc/util.c b/ipc/util.c
index 69a0cc13d966..8fd1b891ec0c 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -329,12 +329,14 @@ retry:
  *
  *      It is called with ipc_ids.rw_mutex and ipcp->lock held.
  */
-static int ipc_check_perms(struct kern_ipc_perm *ipcp, struct ipc_ops *ops,
-                        struct ipc_params *params)
+static int ipc_check_perms(struct ipc_namespace *ns,
+                           struct kern_ipc_perm *ipcp,
+                           struct ipc_ops *ops,
+                           struct ipc_params *params)
 {
         int err;
 
-        if (ipcperms(ipcp, params->flg))
+        if (ipcperms(ns, ipcp, params->flg))
                 err = -EACCES;
         else {
                 err = ops->associate(ipcp, params->flg);
@@ -396,7 +398,7 @@ retry:
                                  * ipc_check_perms returns the IPC id on
                                  * success
                                  */
-                                err = ipc_check_perms(ipcp, ops, params);
+                                err = ipc_check_perms(ns, ipcp, ops, params);
                 }
                 ipc_unlock(ipcp);
         }
@@ -610,10 +612,12 @@ void ipc_rcu_putref(void *ptr)
  *
  *      Check user, group, other permissions for access
  *      to ipc resources. return 0 if allowed
+ *
+ *      @flag will most probably be 0 or S_...UGO from <linux/stat.h>
  */
  
-int ipcperms (struct kern_ipc_perm *ipcp, short flag)
-{       /* flag will most probably be 0 or S_...UGO from <linux/stat.h> */
+int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
+{
         uid_t euid = current_euid();
         int requested_mode, granted_mode;
 
@@ -627,7 +631,7 @@ int ipcperms (struct kern_ipc_perm *ipcp, short flag)
                 granted_mode >>= 3;
         /* is there some bit set in requested_mode but not in granted_mode? */
         if ((requested_mode & ~granted_mode & 0007) && 
-            !capable(CAP_IPC_OWNER))
+            !ns_capable(ns->user_ns, CAP_IPC_OWNER))
                 return -1;
 
         return security_ipc_permission(ipcp, flag);
@@ -765,6 +769,7 @@ void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
 
 /**
  * ipcctl_pre_down - retrieve an ipc and check permissions for some IPC_XXX cmd
+ * @ids:  the ipc namespace
  * @ids:  the table of ids where to look for the ipc
  * @id:   the id of the ipc to retrieve
  * @cmd:  the cmd to check
@@ -779,7 +784,8 @@ void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
  *  - returns the ipc with both ipc and rw_mutex locks held in case of success
  *    or an err-code without any lock held otherwise.
  */
-struct kern_ipc_perm *ipcctl_pre_down(struct ipc_ids *ids, int id, int cmd,
+struct kern_ipc_perm *ipcctl_pre_down(struct ipc_namespace *ns,
+                                      struct ipc_ids *ids, int id, int cmd,
                                       struct ipc64_perm *perm, int extra_perm)
 {
         struct kern_ipc_perm *ipcp;
@@ -799,8 +805,8 @@ struct kern_ipc_perm *ipcctl_pre_down(struct ipc_ids *ids, int id, int cmd,
                                          perm->gid, perm->mode);
 
         euid = current_euid();
-        if (euid == ipcp->cuid ||
-            euid == ipcp->uid  || capable(CAP_SYS_ADMIN))
+        if (euid == ipcp->cuid || euid == ipcp->uid  ||
+            ns_capable(ns->user_ns, CAP_SYS_ADMIN))
                 return ipcp;
 
         err = -EPERM;