userns: Convert the audit loginuid to be a kuid

Always store audit loginuids in type kuid_t.

Print loginuids by converting them into uids in the appropriate user
namespace, and then printing the resulting uid.

Modify audit_get_loginuid to return a kuid_t.

Modify audit_set_loginuid to take a kuid_t.

Modify /proc/<pid>/loginuid on read to convert the loginuid into the
user namespace of the opener of the file.

Modify /proc/<pid>/loginud on write to convert the loginuid
rom the user namespace of the opener of the file.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Paris <eparis@redhat.com>
Cc: Paul Moore <paul@paul-moore.com> ?
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

1 files changed, 10 insertions, 2 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 1b6c84cbdb73..138cff4b05dd 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1089,7 +1089,8 @@ static ssize_t proc_loginuid_read(struct file * file, char __user * buf,
         if (!task)
                 return -ESRCH;
         length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
-                                audit_get_loginuid(task));
+                           from_kuid(file->f_cred->user_ns,
+                                     audit_get_loginuid(task)));
         put_task_struct(task);
         return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
 }
@@ -1101,6 +1102,7 @@ static ssize_t proc_loginuid_write(struct file * file, const char __user * buf,
         char *page, *tmp;
         ssize_t length;
         uid_t loginuid;
+        kuid_t kloginuid;
 
         rcu_read_lock();
         if (current != pid_task(proc_pid(inode), PIDTYPE_PID)) {
@@ -1130,7 +1132,13 @@ static ssize_t proc_loginuid_write(struct file * file, const char __user * buf,
                 goto out_free_page;
 
         }
-        length = audit_set_loginuid(loginuid);
+        kloginuid = make_kuid(file->f_cred->user_ns, loginuid);
+        if (!uid_valid(kloginuid)) {
+                length = -EINVAL;
+                goto out_free_page;
+        }
+
+        length = audit_set_loginuid(kloginuid);
         if (likely(length == 0))
                 length = count;