CRED: Pass credentials through dentry_open()

Pass credentials through dentry_open() so that the COW creds patch can have
SELinux's flush_unauthorized_files() pass the appropriate creds back to itself
when it opens its null chardev.

The security_dentry_open() call also now takes a creds pointer, as does the
dentry_open hook in struct security_operations.

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

1 files changed, 9 insertions, 6 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index cc6e5a3f10cc..f20cbd681ba6 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2150,9 +2150,9 @@ extern struct vfsmount *selinuxfs_mount;
 extern struct dentry *selinux_null;
 
 /* Derived from fs/exec.c:flush_old_files. */
-static inline void flush_unauthorized_files(struct files_struct *files)
+static inline void flush_unauthorized_files(const struct cred *cred,
+                                            struct files_struct *files)
 {
-        const struct cred *cred = current_cred();
         struct avc_audit_data ad;
         struct file *file, *devnull = NULL;
         struct tty_struct *tty;
@@ -2222,7 +2222,10 @@ static inline void flush_unauthorized_files(struct files_struct *files)
                                         if (devnull) {
                                                 get_file(devnull);
                                         } else {
-                                                devnull = dentry_open(dget(selinux_null), mntget(selinuxfs_mount), O_RDWR);
+                                                devnull = dentry_open(
+                                                        dget(selinux_null),
+                                                        mntget(selinuxfs_mount),
+                                                        O_RDWR, cred);
                                                 if (IS_ERR(devnull)) {
                                                         devnull = NULL;
                                                         put_unused_fd(fd);
@@ -2302,6 +2305,7 @@ static void selinux_bprm_apply_creds(struct linux_binprm *bprm, int unsafe)
  */
 static void selinux_bprm_post_apply_creds(struct linux_binprm *bprm)
 {
+        const struct cred *cred = current_cred();
         struct task_security_struct *tsec;
         struct rlimit *rlim, *initrlim;
         struct itimerval itimer;
@@ -2321,7 +2325,7 @@ static void selinux_bprm_post_apply_creds(struct linux_binprm *bprm)
                 return;
 
         /* Close files for which the new task SID is not authorized. */
-        flush_unauthorized_files(current->files);
+        flush_unauthorized_files(cred, current->files);
 
         /* Check whether the new SID can inherit signal state
            from the old SID.  If not, clear itimers to avoid
@@ -3202,9 +3206,8 @@ static int selinux_file_receive(struct file *file)
         return file_has_perm(cred, file, file_to_av(file));
 }
 
-static int selinux_dentry_open(struct file *file)
+static int selinux_dentry_open(struct file *file, const struct cred *cred)
 {
-        const struct cred *cred = current_cred();
         struct file_security_struct *fsec;
         struct inode *inode;
         struct inode_security_struct *isec;