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 <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

4 files changed, 41 insertions, 39 deletions

diff --git a/kernel/cred.c b/kernel/cred.c
index 7a0d8066988..eddc5e2e958 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -49,6 +49,14 @@ struct cred init_cred = {
 	.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,
@@ -488,10 +496,10 @@ int commit_creds(struct cred *new)
 	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);
@@ -500,9 +508,9 @@ int commit_creds(struct cred *new)
 	}
 
 	/* 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
@@ -519,16 +527,16 @@ int commit_creds(struct cred *new)
 	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 */
diff --git a/kernel/signal.c b/kernel/signal.c
index e2c5d84f2da..2734dc965f6 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1038,8 +1038,10 @@ static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_str
 	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)
@@ -1106,7 +1108,7 @@ static int __send_signal(int sig, 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;
@@ -1973,7 +1975,7 @@ static void ptrace_do_notify(int signr, int exit_code, int why)
 	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);
@@ -2828,7 +2830,7 @@ SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
 	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);
 }
@@ -2871,7 +2873,7 @@ static int do_tkill(pid_t tgid, pid_t pid, int sig)
 	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);
 }
diff --git a/kernel/sys.c b/kernel/sys.c
index f0c43b4b665..39962818c00 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -175,7 +175,6 @@ SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval)
 	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)
@@ -209,22 +208,19 @@ SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval)
 			} 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;
 	}
@@ -248,7 +244,6 @@ SYSCALL_DEFINE2(getpriority, int, which, int, who)
 	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)
@@ -280,25 +275,22 @@ SYSCALL_DEFINE2(getpriority, int, which, int, who)
 			} 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;
 	}
@@ -641,7 +633,7 @@ static int set_user(struct cred *new)
 {
 	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;
 
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 7eff867bfac..86602316422 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -36,8 +36,8 @@ static bool new_idmap_permitted(struct user_namespace *ns, int cap_setid,
 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