CRED: Separate task security context from task_struct

Separate the task security context from task_struct.  At this point, the
security data is temporarily embedded in the task_struct with two pointers
pointing to it.

Note that the Alpha arch is altered as it refers to (E)UID and (E)GID in
entry.S via asm-offsets.

With comment fixes Signed-off-by: Marc Dionne <marc.c.dionne@gmail.com>

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 9 insertions, 8 deletions

diff --git a/fs/open.c b/fs/open.c
index 500cc0c54762..b1238e195e7e 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -425,6 +425,7 @@ out:
  */
 asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode)
 {
+        struct cred *cred = current->cred;
         struct path path;
         struct inode *inode;
         int old_fsuid, old_fsgid;
@@ -434,18 +435,18 @@ asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode)
         if (mode & ~S_IRWXO)    /* where's F_OK, X_OK, W_OK, R_OK? */
                 return -EINVAL;
 
-        old_fsuid = current->fsuid;
-        old_fsgid = current->fsgid;
+        old_fsuid = cred->fsuid;
+        old_fsgid = cred->fsgid;
 
-        current->fsuid = current->uid;
-        current->fsgid = current->gid;
+        cred->fsuid = cred->uid;
+        cred->fsgid = cred->gid;
 
         if (!issecure(SECURE_NO_SETUID_FIXUP)) {
                 /* Clear the capabilities if we switch to a non-root user */
-                if (current->uid)
+                if (current->cred->uid)
                         old_cap = cap_set_effective(__cap_empty_set);
                 else
-                        old_cap = cap_set_effective(current->cap_permitted);
+                        old_cap = cap_set_effective(cred->cap_permitted);
         }
 
         res = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
@@ -484,8 +485,8 @@ asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode)
 out_path_release:
         path_put(&path);
 out:
-        current->fsuid = old_fsuid;
-        current->fsgid = old_fsgid;
+        cred->fsuid = old_fsuid;
+        cred->fsgid = old_fsgid;
 
         if (!issecure(SECURE_NO_SETUID_FIXUP))
                 cap_set_effective(old_cap);