[PATCH 01/35] Revert "capabitlies: ns_capable can use the cap helpers rather than lsm call"

[Eric Paris <eparis@xxxxxxxxxx>]

From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>

This reverts commit d2a7009f0bb03fa22ad08dd25472efa0568126b9.

J. R. Okajima explains:

 "After this commit, I am afraid access(2) on NFS may not work
  correctly.  The scenario based upon my guess.
   - access(2) overrides the credentials.
   - calls inode_permission() -- ... -- generic_permission() --
      ns_capable().
   - while the old ns_capable() calls security_capable(current_cred()),
     the new ns_capable() calls has_ns_capability(current) --
     security_capable(__task_cred(t)).

  current_cred() returns current->cred which is effective (overridden)
  credentials, but __task_cred(current) returns current->real_cred (the
  NFSD's credential).  And the overridden credentials by access(2) lost."

Requested-by: J. R. Okajima <hooanon05@xxxxxxxxxxx>
Acked-by: Eric Paris <eparis@xxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
---
 kernel/capability.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/capability.c b/kernel/capability.c
index 74fb3b6..0b6b229 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -384,7 +384,7 @@ bool ns_capable(struct user_namespace *ns, int cap)
 		BUG();
 	}
 
-	if (has_ns_capability(current, ns, cap)) {
+	if (security_capable(current_cred(), ns, cap) == 0) {
 		current->flags |= PF_SUPERPRIV;
 		return true;
 	}
-- 
1.7.1

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