userns: Convert setting and getting uid and gid system calls to use k…

…uid and kgid

Convert setregid, setgid, setreuid, setuid,
setresuid, getresuid, setresgid, getresgid, setfsuid, setfsgid,
getuid, geteuid, getgid, getegid,
waitpid, waitid, wait4.

Convert userspace uids and gids into kuids and kgids before
being placed on struct cred.  Convert struct cred kuids and
kgids into userspace uids and gids when returning them.

Signed-off-by: Eric W. Biederman <[email protected]>

kernel/exit.c

@@ -1214,7 +1214,7 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
 	unsigned long state;
 	int retval, status, traced;
 	pid_t pid = task_pid_vnr(p);
-	uid_t uid = __task_cred(p)->uid;
+	uid_t uid = from_kuid_munged(current_user_ns(), __task_cred(p)->uid);
 	struct siginfo __user *infop;
 
 	if (!likely(wo->wo_flags & WEXITED))
@@ -1427,7 +1427,7 @@ static int wait_task_stopped(struct wait_opts *wo,
 	if (!unlikely(wo->wo_flags & WNOWAIT))
 		*p_code = 0;
 
-	uid = task_uid(p);
+	uid = from_kuid_munged(current_user_ns(), __task_cred(p)->uid);
 unlock_sig:
 	spin_unlock_irq(&p->sighand->siglock);
 	if (!exit_code)
@@ -1500,7 +1500,7 @@ static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
 	}
 	if (!unlikely(wo->wo_flags & WNOWAIT))
 		p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
-	uid = task_uid(p);
+	uid = from_kuid_munged(current_user_ns(), __task_cred(p)->uid);
 	spin_unlock_irq(&p->sighand->siglock);
 
 	pid = task_pid_vnr(p);