userns: Store uid and gid values in struct cred with kuid_t and kgid_t types

cred.h and a few trivial users of struct cred are changed. The rest of the users
of struct cred are left for other patches as there are too many changes to make
in one go and leave the change reviewable. If the user namespace is disabled and
CONFIG_UIDGID_STRICT_TYPE_CHECKS are disabled the code will contiue to compile
and behave correctly.

Acked-by: Serge Hallyn <[e-mail]>
Signed-off-by: Eric W. Biederman <[e-mail]>

arch/x86/mm/fault.c

···
 		pte_t *pte = lookup_address(address, &level);
 
 		if (pte && pte_present(*pte) && !pte_exec(*pte))
-			printk(nx_warning, current_uid());
+			printk(nx_warning, from_kuid(&init_user_ns, current_uid()));
 	}
 
 	printk(KERN_ALERT "BUG: unable to handle kernel ");

fs/ioprio.c

···
 				break;
 
 			do_each_thread(g, p) {
-				const struct cred *tcred = __task_cred(p);
-				kuid_t tcred_uid = make_kuid(tcred->user_ns, tcred->uid);
-				if (!uid_eq(tcred_uid, uid))
+				if (!uid_eq(task_uid(p), uid))
 					continue;
 				ret = set_task_ioprio(p, ioprio);
 				if (ret)
···
 				break;
 
 			do_each_thread(g, p) {
-				const struct cred *tcred = __task_cred(p);
-				kuid_t tcred_uid = make_kuid(tcred->user_ns, tcred->uid);
-				if (!uid_eq(tcred_uid, user->uid))
+				if (!uid_eq(task_uid(p), user->uid))
 					continue;
 				tmpio = get_task_ioprio(p);
 				if (tmpio < 0)

include/linux/cred.h

···
 #define CRED_MAGIC	0x43736564
 #define CRED_MAGIC_DEAD	0x44656144
 #endif
-	uid_t		uid;		/* real UID of the task */
-	gid_t		gid;		/* real GID of the task */
-	uid_t		suid;		/* saved UID of the task */
-	gid_t		sgid;		/* saved GID of the task */
-	uid_t		euid;		/* effective UID of the task */
-	gid_t		egid;		/* effective GID of the task */
-	uid_t		fsuid;		/* UID for VFS ops */
-	gid_t		fsgid;		/* GID for VFS ops */
+	kuid_t		uid;		/* real UID of the task */
+	kgid_t		gid;		/* real GID of the task */
+	kuid_t		suid;		/* saved UID of the task */
+	kgid_t		sgid;		/* saved GID of the task */
+	kuid_t		euid;		/* effective UID of the task */
+	kgid_t		egid;		/* effective GID of the task */
+	kuid_t		fsuid;		/* UID for VFS ops */
+	kgid_t		fsgid;		/* GID for VFS ops */
 	unsigned	securebits;	/* SUID-less security management */
 	kernel_cap_t	cap_inheritable; /* caps our children can inherit */
 	kernel_cap_t	cap_permitted;	/* caps we're permitted */

include/linux/user_namespace.h

···
 #endif
 
 static inline uid_t user_ns_map_uid(struct user_namespace *to,
-	const struct cred *cred, uid_t uid)
+	const struct cred *cred, kuid_t uid)
 {
-	return from_kuid_munged(to, make_kuid(cred->user_ns, uid));
+	return from_kuid_munged(to, uid);
 }
 
 static inline gid_t user_ns_map_gid(struct user_namespace *to,
-	const struct cred *cred, gid_t gid)
+	const struct cred *cred, kgid_t gid)
 {
-	return from_kgid_munged(to, make_kgid(cred->user_ns, gid));
+	return from_kgid_munged(to, gid);
 }
 
 #endif /* _LINUX_USER_H */

kernel/cred.c

···
 	.subscribers		= ATOMIC_INIT(2),
 	.magic			= CRED_MAGIC,
 #endif
+	.uid			= GLOBAL_ROOT_UID,
+	.gid			= GLOBAL_ROOT_GID,
+	.suid			= GLOBAL_ROOT_UID,
+	.sgid			= GLOBAL_ROOT_GID,
+	.euid			= GLOBAL_ROOT_UID,
+	.egid			= GLOBAL_ROOT_GID,
+	.fsuid			= GLOBAL_ROOT_UID,
+	.fsgid			= GLOBAL_ROOT_GID,
 	.securebits		= SECUREBITS_DEFAULT,
 	.cap_inheritable	= CAP_EMPTY_SET,
 	.cap_permitted		= CAP_FULL_SET,
···
 	get_cred(new); /* we will require a ref for the subj creds too */
 
 	/* dumpability changes */
-	if (old->euid != new->euid ||
-	    old->egid != new->egid ||
-	    old->fsuid != new->fsuid ||
-	    old->fsgid != new->fsgid ||
+	if (!uid_eq(old->euid, new->euid) ||
+	    !gid_eq(old->egid, new->egid) ||
+	    !uid_eq(old->fsuid, new->fsuid) ||
+	    !gid_eq(old->fsgid, new->fsgid) ||
 	    !cap_issubset(new->cap_permitted, old->cap_permitted)) {
 		if (task->mm)
 			set_dumpable(task->mm, suid_dumpable);
···
 	}
 
 	/* alter the thread keyring */
-	if (new->fsuid != old->fsuid)
+	if (!uid_eq(new->fsuid, old->fsuid))
 		key_fsuid_changed(task);
-	if (new->fsgid != old->fsgid)
+	if (!gid_eq(new->fsgid, old->fsgid))
 		key_fsgid_changed(task);
 
 	/* do it
···
 	alter_cred_subscribers(old, -2);
 
 	/* send notifications */
-	if (new->uid   != old->uid  ||
-	    new->euid  != old->euid ||
-	    new->suid  != old->suid ||
-	    new->fsuid != old->fsuid)
+	if (!uid_eq(new->uid,   old->uid)  ||
+	    !uid_eq(new->euid,  old->euid) ||
+	    !uid_eq(new->suid,  old->suid) ||
+	    !uid_eq(new->fsuid, old->fsuid))
 		proc_id_connector(task, PROC_EVENT_UID);
 
-	if (new->gid   != old->gid  ||
-	    new->egid  != old->egid ||
-	    new->sgid  != old->sgid ||
-	    new->fsgid != old->fsgid)
+	if (!gid_eq(new->gid,   old->gid)  ||
+	    !gid_eq(new->egid,  old->egid) ||
+	    !gid_eq(new->sgid,  old->sgid) ||
+	    !gid_eq(new->fsgid, old->fsgid))
 		proc_id_connector(task, PROC_EVENT_GID);
 
 	/* release the old obj and subj refs both */

kernel/signal.c

···
 	if (SI_FROMKERNEL(info))
 		return;
 
-	info->si_uid = user_ns_map_uid(task_cred_xxx(t, user_ns),
-					current_cred(), info->si_uid);
+	rcu_read_lock();
+	info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
+					make_kuid(current_user_ns(), info->si_uid));
+	rcu_read_unlock();
 }
 #else
 static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
···
 			q->info.si_code = SI_USER;
 			q->info.si_pid = task_tgid_nr_ns(current,
 							task_active_pid_ns(t));
-			q->info.si_uid = current_uid();
+			q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
 			break;
 		case (unsigned long) SEND_SIG_PRIV:
 			q->info.si_signo = sig;
···
 	info.si_signo = signr;
 	info.si_code = exit_code;
 	info.si_pid = task_pid_vnr(current);
-	info.si_uid = current_uid();
+	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
 
 	/* Let the debugger run.  */
 	ptrace_stop(exit_code, why, 1, &info);
···
 	info.si_errno = 0;
 	info.si_code = SI_USER;
 	info.si_pid = task_tgid_vnr(current);
-	info.si_uid = current_uid();
+	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
 
 	return kill_something_info(sig, &info, pid);
 }
···
 	info.si_errno = 0;
 	info.si_code = SI_TKILL;
 	info.si_pid = task_tgid_vnr(current);
-	info.si_uid = current_uid();
+	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
 
 	return do_send_specific(tgid, pid, sig, &info);
 }

kernel/sys.c

···
 	const struct cred *cred = current_cred();
 	int error = -EINVAL;
 	struct pid *pgrp;
-	kuid_t cred_uid;
 	kuid_t uid;
 
 	if (which > PRIO_USER || which < PRIO_PROCESS)
···
 			} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
 			break;
 		case PRIO_USER:
-			cred_uid = make_kuid(cred->user_ns, cred->uid);
 			uid = make_kuid(cred->user_ns, who);
 			user = cred->user;
 			if (!who)
-				uid = cred_uid;
-			else if (!uid_eq(uid, cred_uid) &&
+				uid = cred->uid;
+			else if (!uid_eq(uid, cred->uid) &&
 				 !(user = find_user(uid)))
 				goto out_unlock;	/* No processes for this user */
 
 			do_each_thread(g, p) {
-				const struct cred *tcred = __task_cred(p);
-				kuid_t tcred_uid = make_kuid(tcred->user_ns, tcred->uid);
-				if (uid_eq(tcred_uid, uid))
+				if (uid_eq(task_uid(p), uid))
 					error = set_one_prio(p, niceval, error);
 			} while_each_thread(g, p);
-			if (!uid_eq(uid, cred_uid))
+			if (!uid_eq(uid, cred->uid))
 				free_uid(user);		/* For find_user() */
 			break;
 	}
···
 	const struct cred *cred = current_cred();
 	long niceval, retval = -ESRCH;
 	struct pid *pgrp;
-	kuid_t cred_uid;
 	kuid_t uid;
 
 	if (which > PRIO_USER || which < PRIO_PROCESS)
···
 			} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
 			break;
 		case PRIO_USER:
-			cred_uid = make_kuid(cred->user_ns, cred->uid);
 			uid = make_kuid(cred->user_ns, who);
 			user = cred->user;
 			if (!who)
-				uid = cred_uid;
-			else if (!uid_eq(uid, cred_uid) &&
+				uid = cred->uid;
+			else if (!uid_eq(uid, cred->uid) &&
 				 !(user = find_user(uid)))
 				goto out_unlock;	/* No processes for this user */
 
 			do_each_thread(g, p) {
-				const struct cred *tcred = __task_cred(p);
-				kuid_t tcred_uid = make_kuid(tcred->user_ns, tcred->uid);
-				if (uid_eq(tcred_uid, uid)) {
+				if (uid_eq(task_uid(p), uid)) {
 					niceval = 20 - task_nice(p);
 					if (niceval > retval)
 						retval = niceval;
 				}
 			} while_each_thread(g, p);
-			if (!uid_eq(uid, cred_uid))
+			if (!uid_eq(uid, cred->uid))
 				free_uid(user);		/* for find_user() */
 			break;
 	}
···
 {
 	struct user_struct *new_user;
 
-	new_user = alloc_uid(make_kuid(new->user_ns, new->uid));
+	new_user = alloc_uid(new->uid);
 	if (!new_user)
 		return -EAGAIN;
 

kernel/user_namespace.c

···
 int create_user_ns(struct cred *new)
 {
 	struct user_namespace *ns, *parent_ns = new->user_ns;
-	kuid_t owner = make_kuid(new->user_ns, new->euid);
-	kgid_t group = make_kgid(new->user_ns, new->egid);
+	kuid_t owner = new->euid;
+	kgid_t group = new->egid;
 
 	/* The creator needs a mapping in the parent user namespace
 	 * or else we won't be able to reasonably tell userspace who

mm/oom_kill.c

···
 		}
 
 		pr_info("[%5d] %5d %5d %8lu %8lu %3u     %3d         %5d %s\n",
-			task->pid, task_uid(task), task->tgid,
-			task->mm->total_vm, get_mm_rss(task->mm),
+			task->pid, from_kuid(&init_user_ns, task_uid(task)),
+			task->tgid, task->mm->total_vm, get_mm_rss(task->mm),
 			task_cpu(task), task->signal->oom_adj,
 			task->signal->oom_score_adj, task->comm);
 		task_unlock(task);

security/commoncap.c

···
 {
 	for (;;) {
 		/* The owner of the user namespace has all caps. */
-		if (targ_ns != &init_user_ns && uid_eq(targ_ns->owner,
-						       make_kuid(cred->user_ns, cred->euid)))
+		if (targ_ns != &init_user_ns && uid_eq(targ_ns->owner, cred->euid))
 			return 0;
 
 		/* Do we have the necessary capabilities? */