1 files changed, 682 insertions, 846 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 0087cf9..d0066e1 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -136,7 +136,7 @@ static int do_getname(const char __user *filename, char *page)
 	return retval;
 }
 
-char * getname(const char __user * filename)
+static char *getname_flags(const char __user * filename, int flags)
 {
 	char *tmp, *result;
 
@@ -147,14 +147,21 @@ char * getname(const char __user * filename)
 
 		result = tmp;
 		if (retval < 0) {
-			__putname(tmp);
-			result = ERR_PTR(retval);
+			if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) {
+				__putname(tmp);
+				result = ERR_PTR(retval);
+			}
 		}
 	}
 	audit_getname(result);
 	return result;
 }
 
+char *getname(const char __user * filename)
+{
+	return getname_flags(filename, 0);
+}
+
 #ifdef CONFIG_AUDITSYSCALL
 void putname(const char *name)
 {
@@ -176,6 +183,9 @@ static int acl_permission_check(struct inode *inode, int mask, unsigned int flag
 
 	mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
 
+	if (current_user_ns() != inode_userns(inode))
+		goto other_perms;
+
 	if (current_fsuid() == inode->i_uid)
 		mode >>= 6;
 	else {
@@ -189,6 +199,7 @@ static int acl_permission_check(struct inode *inode, int mask, unsigned int flag
 			mode >>= 3;
 	}
 
+other_perms:
 	/*
 	 * If the DACs are ok we don't need any capability check.
 	 */
@@ -230,7 +241,7 @@ int generic_permission(struct inode *inode, int mask, unsigned int flags,
 	 * Executable DACs are overridable if at least one exec bit is set.
 	 */
 	if (!(mask & MAY_EXEC) || execute_ok(inode))
-		if (capable(CAP_DAC_OVERRIDE))
+		if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
 			return 0;
 
 	/*
@@ -238,7 +249,7 @@ int generic_permission(struct inode *inode, int mask, unsigned int flags,
 	 */
 	mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
 	if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE)))
-		if (capable(CAP_DAC_READ_SEARCH))
+		if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
 			return 0;
 
 	return -EACCES;
@@ -401,9 +412,11 @@ static int nameidata_drop_rcu(struct nameidata *nd)
 {
 	struct fs_struct *fs = current->fs;
 	struct dentry *dentry = nd->path.dentry;
+	int want_root = 0;
 
 	BUG_ON(!(nd->flags & LOOKUP_RCU));
-	if (nd->root.mnt) {
+	if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
+		want_root = 1;
 		spin_lock(&fs->lock);
 		if (nd->root.mnt != fs->root.mnt ||
 				nd->root.dentry != fs->root.dentry)
@@ -414,7 +427,7 @@ static int nameidata_drop_rcu(struct nameidata *nd)
 		goto err;
 	BUG_ON(nd->inode != dentry->d_inode);
 	spin_unlock(&dentry->d_lock);
-	if (nd->root.mnt) {
+	if (want_root) {
 		path_get(&nd->root);
 		spin_unlock(&fs->lock);
 	}
@@ -427,7 +440,7 @@ static int nameidata_drop_rcu(struct nameidata *nd)
 err:
 	spin_unlock(&dentry->d_lock);
 err_root:
-	if (nd->root.mnt)
+	if (want_root)
 		spin_unlock(&fs->lock);
 	return -ECHILD;
 }
@@ -454,9 +467,11 @@ static int nameidata_dentry_drop_rcu(struct nameidata *nd, struct dentry *dentry
 {
 	struct fs_struct *fs = current->fs;
 	struct dentry *parent = nd->path.dentry;
+	int want_root = 0;
 
 	BUG_ON(!(nd->flags & LOOKUP_RCU));
-	if (nd->root.mnt) {
+	if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
+		want_root = 1;
 		spin_lock(&fs->lock);
 		if (nd->root.mnt != fs->root.mnt ||
 				nd->root.dentry != fs->root.dentry)
@@ -476,7 +491,7 @@ static int nameidata_dentry_drop_rcu(struct nameidata *nd, struct dentry *dentry
 	parent->d_count++;
 	spin_unlock(&dentry->d_lock);
 	spin_unlock(&parent->d_lock);
-	if (nd->root.mnt) {
+	if (want_root) {
 		path_get(&nd->root);
 		spin_unlock(&fs->lock);
 	}
@@ -490,7 +505,7 @@ err:
 	spin_unlock(&dentry->d_lock);
 	spin_unlock(&parent->d_lock);
 err_root:
-	if (nd->root.mnt)
+	if (want_root)
 		spin_unlock(&fs->lock);
 	return -ECHILD;
 }
@@ -498,8 +513,16 @@ err_root:
 /* Try to drop out of rcu-walk mode if we were in it, otherwise do nothing.  */
 static inline int nameidata_dentry_drop_rcu_maybe(struct nameidata *nd, struct dentry *dentry)
 {
-	if (nd->flags & LOOKUP_RCU)
-		return nameidata_dentry_drop_rcu(nd, dentry);
+	if (nd->flags & LOOKUP_RCU) {
+		if (unlikely(nameidata_dentry_drop_rcu(nd, dentry))) {
+			nd->flags &= ~LOOKUP_RCU;
+			if (!(nd->flags & LOOKUP_ROOT))
+				nd->root.mnt = NULL;
+			rcu_read_unlock();
+			br_read_unlock(vfsmount_lock);
+			return -ECHILD;
+		}
+	}
 	return 0;
 }
 
@@ -518,7 +541,8 @@ static int nameidata_drop_rcu_last(struct nameidata *nd)
 
 	BUG_ON(!(nd->flags & LOOKUP_RCU));
 	nd->flags &= ~LOOKUP_RCU;
-	nd->root.mnt = NULL;
+	if (!(nd->flags & LOOKUP_ROOT))
+		nd->root.mnt = NULL;
 	spin_lock(&dentry->d_lock);
 	if (!__d_rcu_to_refcount(dentry, nd->seq))
 		goto err_unlock;
@@ -539,14 +563,6 @@ err_unlock:
 	return -ECHILD;
 }
 
-/* Try to drop out of rcu-walk mode if we were in it, otherwise do nothing.  */
-static inline int nameidata_drop_rcu_last_maybe(struct nameidata *nd)
-{
-	if (likely(nd->flags & LOOKUP_RCU))
-		return nameidata_drop_rcu_last(nd);
-	return 0;
-}
-
 /**
  * release_open_intent - free up open intent resources
  * @nd: pointer to nameidata
@@ -590,42 +606,8 @@ do_revalidate(struct dentry *dentry, struct nameidata *nd)
 	return dentry;
 }
 
-static inline struct dentry *
-do_revalidate_rcu(struct dentry *dentry, struct nameidata *nd)
-{
-	int status = d_revalidate(dentry, nd);
-	if (likely(status > 0))
-		return dentry;
-	if (status == -ECHILD) {
-		if (nameidata_dentry_drop_rcu(nd, dentry))
-			return ERR_PTR(-ECHILD);
-		return do_revalidate(dentry, nd);
-	}
-	if (status < 0)
-		return ERR_PTR(status);
-	/* Don't d_invalidate in rcu-walk mode */
-	if (nameidata_dentry_drop_rcu(nd, dentry))
-		return ERR_PTR(-ECHILD);
-	if (!d_invalidate(dentry)) {
-		dput(dentry);
-		dentry = NULL;
-	}
-	return dentry;
-}
-
-static inline int need_reval_dot(struct dentry *dentry)
-{
-	if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE)))
-		return 0;
-
-	if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)))
-		return 0;
-
-	return 1;
-}
-
 /*
- * force_reval_path - force revalidation of a dentry
+ * handle_reval_path - force revalidation of a dentry
  *
  * In some situations the path walking code will trust dentries without
  * revalidating them. This causes problems for filesystems that depend on
@@ -639,27 +621,28 @@ static inline int need_reval_dot(struct dentry *dentry)
  * invalidate the dentry. It's up to the caller to handle putting references
  * to the path if necessary.
  */
-static int
-force_reval_path(struct path *path, struct nameidata *nd)
+static inline int handle_reval_path(struct nameidata *nd)
 {
+	struct dentry *dentry = nd->path.dentry;
 	int status;
-	struct dentry *dentry = path->dentry;
 
-	/*
-	 * only check on filesystems where it's possible for the dentry to
-	 * become stale.
-	 */
-	if (!need_reval_dot(dentry))
+	if (likely(!(nd->flags & LOOKUP_JUMPED)))
 		return 0;
 
+	if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE)))
+		return 0;
+
+	if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)))
+		return 0;
+
+	/* Note: we do not d_invalidate() */
 	status = d_revalidate(dentry, nd);
 	if (status > 0)
 		return 0;
 
-	if (!status) {
-		d_invalidate(dentry);
+	if (!status)
 		status = -ESTALE;
-	}
+
 	return status;
 }
 
@@ -675,6 +658,7 @@ force_reval_path(struct path *path, struct nameidata *nd)
 static inline int exec_permission(struct inode *inode, unsigned int flags)
 {
 	int ret;
+	struct user_namespace *ns = inode_userns(inode);
 
 	if (inode->i_op->permission) {
 		ret = inode->i_op->permission(inode, MAY_EXEC, flags);
@@ -687,7 +671,8 @@ static inline int exec_permission(struct inode *inode, unsigned int flags)
 	if (ret == -ECHILD)
 		return ret;
 
-	if (capable(CAP_DAC_OVERRIDE) || capable(CAP_DAC_READ_SEARCH))
+	if (ns_capable(ns, CAP_DAC_OVERRIDE) ||
+			ns_capable(ns, CAP_DAC_READ_SEARCH))
 		goto ok;
 
 	return ret;
@@ -728,6 +713,7 @@ static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *l
 		path_put(&nd->path);
 		nd->path = nd->root;
 		path_get(&nd->root);
+		nd->flags |= LOOKUP_JUMPED;
 	}
 	nd->inode = nd->path.dentry->d_inode;
 
@@ -757,19 +743,42 @@ static inline void path_to_nameidata(const struct path *path,
 	nd->path.dentry = path->dentry;
 }
 
+static inline void put_link(struct nameidata *nd, struct path *link, void *cookie)
+{
+	struct inode *inode = link->dentry->d_inode;
+	if (!IS_ERR(cookie) && inode->i_op->put_link)
+		inode->i_op->put_link(link->dentry, nd, cookie);
+	path_put(link);
+}
+
 static __always_inline int
-__do_follow_link(const struct path *link, struct nameidata *nd, void **p)
+follow_link(struct path *link, struct nameidata *nd, void **p)
 {
 	int error;
 	struct dentry *dentry = link->dentry;
 
 	BUG_ON(nd->flags & LOOKUP_RCU);
 
+	if (link->mnt == nd->path.mnt)
+		mntget(link->mnt);
+
+	if (unlikely(current->total_link_count >= 40)) {
+		*p = ERR_PTR(-ELOOP); /* no ->put_link(), please */
+		path_put(&nd->path);
+		return -ELOOP;
+	}
+	cond_resched();
+	current->total_link_count++;
+
 	touch_atime(link->mnt, dentry);
 	nd_set_link(nd, NULL);
 
-	if (link->mnt == nd->path.mnt)
-		mntget(link->mnt);
+	error = security_inode_follow_link(link->dentry, nd);
+	if (error) {
+		*p = ERR_PTR(error); /* no ->put_link(), please */
+		path_put(&nd->path);
+		return error;
+	}
 
 	nd->last_type = LAST_BIND;
 	*p = dentry->d_inode->i_op->follow_link(dentry, nd);
@@ -780,56 +789,18 @@ __do_follow_link(const struct path *link, struct nameidata *nd, void **p)
 		if (s)
 			error = __vfs_follow_link(nd, s);
 		else if (nd->last_type == LAST_BIND) {
-			error = force_reval_path(&nd->path, nd);
-			if (error)
+			nd->flags |= LOOKUP_JUMPED;
+			nd->inode = nd->path.dentry->d_inode;
+			if (nd->inode->i_op->follow_link) {
+				/* stepped on a _really_ weird one */
 				path_put(&nd->path);
+				error = -ELOOP;
+			}
 		}
 	}
 	return error;
 }
 
-/*
- * This limits recursive symlink follows to 8, while
- * limiting consecutive symlinks to 40.
- *
- * Without that kind of total limit, nasty chains of consecutive
- * symlinks can cause almost arbitrarily long lookups. 
- */
-static inline int do_follow_link(struct inode *inode, struct path *path, struct nameidata *nd)
-{
-	void *cookie;
-	int err = -ELOOP;
-
-	/* We drop rcu-walk here */
-	if (nameidata_dentry_drop_rcu_maybe(nd, path->dentry))
-		return -ECHILD;
-	BUG_ON(inode != path->dentry->d_inode);
-
-	if (current->link_count >= MAX_NESTED_LINKS)
-		goto loop;
-	if (current->total_link_count >= 40)
-		goto loop;
-	BUG_ON(nd->depth >= MAX_NESTED_LINKS);
-	cond_resched();
-	err = security_inode_follow_link(path->dentry, nd);
-	if (err)
-		goto loop;
-	current->link_count++;
-	current->total_link_count++;
-	nd->depth++;
-	err = __do_follow_link(path, nd, &cookie);
-	if (!IS_ERR(cookie) && path->dentry->d_inode->i_op->put_link)
-		path->dentry->d_inode->i_op->put_link(path->dentry, nd, cookie);
-	path_put(path);
-	current->link_count--;
-	nd->depth--;
-	return err;
-loop:
-	path_put_conditional(path, nd);
-	path_put(&nd->path);
-	return err;
-}
-
 static int follow_up_rcu(struct path *path)
 {
 	struct vfsmount *parent;
@@ -968,8 +939,7 @@ static int follow_managed(struct path *path, unsigned flags)
 		if (managed & DCACHE_MANAGE_TRANSIT) {
 			BUG_ON(!path->dentry->d_op);
 			BUG_ON(!path->dentry->d_op->d_manage);
-			ret = path->dentry->d_op->d_manage(path->dentry,
-							   false, false);
+			ret = path->dentry->d_op->d_manage(path->dentry, false);
 			if (ret < 0)
 				return ret == -EISDIR ? 0 : ret;
 		}
@@ -1034,7 +1004,7 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
 		struct vfsmount *mounted;
 		if (unlikely(path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) &&
 		    !reverse_transit &&
-		    path->dentry->d_op->d_manage(path->dentry, false, true) < 0)
+		    path->dentry->d_op->d_manage(path->dentry, true) < 0)
 			return false;
 		mounted = __lookup_mnt(path->mnt, path->dentry, 1);
 		if (!mounted)
@@ -1068,7 +1038,7 @@ static int follow_dotdot_rcu(struct nameidata *nd)
 
 			seq = read_seqcount_begin(&parent->d_seq);
 			if (read_seqcount_retry(&old->d_seq, nd->seq))
-				return -ECHILD;
+				goto failed;
 			inode = parent->d_inode;
 			nd->path.dentry = parent;
 			nd->seq = seq;
@@ -1081,8 +1051,15 @@ static int follow_dotdot_rcu(struct nameidata *nd)
 	}
 	__follow_mount_rcu(nd, &nd->path, &inode, true);
 	nd->inode = inode;
-
 	return 0;
+
+failed:
+	nd->flags &= ~LOOKUP_RCU;
+	if (!(nd->flags & LOOKUP_ROOT))
+		nd->root.mnt = NULL;
+	rcu_read_unlock();
+	br_read_unlock(vfsmount_lock);
+	return -ECHILD;
 }
 
 /*
@@ -1093,7 +1070,7 @@ static int follow_dotdot_rcu(struct nameidata *nd)
  * Care must be taken as namespace_sem may be held (indicated by mounting_here
  * being true).
  */
-int follow_down(struct path *path, bool mounting_here)
+int follow_down(struct path *path)
 {
 	unsigned managed;
 	int ret;
@@ -1114,7 +1091,7 @@ int follow_down(struct path *path, bool mounting_here)
 			BUG_ON(!path->dentry->d_op);
 			BUG_ON(!path->dentry->d_op->d_manage);
 			ret = path->dentry->d_op->d_manage(
-				path->dentry, mounting_here, false);
+				path->dentry, false);
 			if (ret < 0)
 				return ret == -EISDIR ? 0 : ret;
 		}
@@ -1216,68 +1193,85 @@ static int do_lookup(struct nameidata *nd, struct qstr *name,
 {
 	struct vfsmount *mnt = nd->path.mnt;
 	struct dentry *dentry, *parent = nd->path.dentry;
-	struct inode *dir;
+	int need_reval = 1;
+	int status = 1;
 	int err;
 
 	/*
-	 * See if the low-level filesystem might want
-	 * to use its own hash..
-	 */
-	if (unlikely(parent->d_flags & DCACHE_OP_HASH)) {
-		err = parent->d_op->d_hash(parent, nd->inode, name);
-		if (err < 0)
-			return err;
-	}
-
-	/*
 	 * Rename seqlock is not required here because in the off chance
 	 * of a false negative due to a concurrent rename, we're going to
 	 * do the non-racy lookup, below.
 	 */
 	if (nd->flags & LOOKUP_RCU) {
 		unsigned seq;
-
 		*inode = nd->inode;
 		dentry = __d_lookup_rcu(parent, name, &seq, inode);
-		if (!dentry) {
-			if (nameidata_drop_rcu(nd))
-				return -ECHILD;
-			goto need_lookup;
-		}
+		if (!dentry)
+			goto unlazy;
+
 		/* Memory barrier in read_seqcount_begin of child is enough */
 		if (__read_seqcount_retry(&parent->d_seq, nd->seq))
 			return -ECHILD;
-
 		nd->seq = seq;
+
 		if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
-			dentry = do_revalidate_rcu(dentry, nd);
-			if (!dentry)
-				goto need_lookup;
-			if (IS_ERR(dentry))
-				goto fail;
-			if (!(nd->flags & LOOKUP_RCU))
-				goto done;
+			status = d_revalidate(dentry, nd);
+			if (unlikely(status <= 0)) {
+				if (status != -ECHILD)
+					need_reval = 0;
+				goto unlazy;
+			}
 		}
 		path->mnt = mnt;
 		path->dentry = dentry;
 		if (likely(__follow_mount_rcu(nd, path, inode, false)))
 			return 0;
-		if (nameidata_drop_rcu(nd))
-			return -ECHILD;
-		/* fallthru */
+unlazy:
+		if (dentry) {
+			if (nameidata_dentry_drop_rcu(nd, dentry))
+				return -ECHILD;
+		} else {
+			if (nameidata_drop_rcu(nd))
+				return -ECHILD;
+		}
+	} else {
+		dentry = __d_lookup(parent, name);
 	}
-	dentry = __d_lookup(parent, name);
-	if (!dentry)
-		goto need_lookup;
-found:
-	if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
-		dentry = do_revalidate(dentry, nd);
-		if (!dentry)
-			goto need_lookup;
-		if (IS_ERR(dentry))
-			goto fail;
+
+retry:
+	if (unlikely(!dentry)) {
+		struct inode *dir = parent->d_inode;
+		BUG_ON(nd->inode != dir);
+
+		mutex_lock(&dir->i_mutex);
+		dentry = d_lookup(parent, name);
+		if (likely(!dentry)) {
+			dentry = d_alloc_and_lookup(parent, name, nd);
+			if (IS_ERR(dentry)) {
+				mutex_unlock(&dir->i_mutex);
+				return PTR_ERR(dentry);
+			}
+			/* known good */
+			need_reval = 0;
+			status = 1;
+		}
+		mutex_unlock(&dir->i_mutex);
 	}
-done:
+	if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval)
+		status = d_revalidate(dentry, nd);
+	if (unlikely(status <= 0)) {
+		if (status < 0) {
+			dput(dentry);
+			return status;
+		}
+		if (!d_invalidate(dentry)) {
+			dput(dentry);
+			dentry = NULL;
+			need_reval = 1;
+			goto retry;
+		}
+	}
+
 	path->mnt = mnt;
 	path->dentry = dentry;
 	err = follow_managed(path, nd->flags);
@@ -1287,39 +1281,113 @@ done:
 	}
 	*inode = path->dentry->d_inode;
 	return 0;
+}
+
+static inline int may_lookup(struct nameidata *nd)
+{
+	if (nd->flags & LOOKUP_RCU) {
+		int err = exec_permission(nd->inode, IPERM_FLAG_RCU);
+		if (err != -ECHILD)
+			return err;
+		if (nameidata_drop_rcu(nd))
+			return -ECHILD;
+	}
+	return exec_permission(nd->inode, 0);
+}
 
-need_lookup:
-	dir = parent->d_inode;
-	BUG_ON(nd->inode != dir);
+static inline int handle_dots(struct nameidata *nd, int type)
+{
+	if (type == LAST_DOTDOT) {
+		if (nd->flags & LOOKUP_RCU) {
+			if (follow_dotdot_rcu(nd))
+				return -ECHILD;
+		} else
+			follow_dotdot(nd);
+	}
+	return 0;
+}
 
-	mutex_lock(&dir->i_mutex);
-	/*
-	 * First re-do the cached lookup just in case it was created
-	 * while we waited for the directory semaphore, or the first
-	 * lookup failed due to an unrelated rename.
-	 *
-	 * This could use version numbering or similar to avoid unnecessary
-	 * cache lookups, but then we'd have to do the first lookup in the
-	 * non-racy way. However in the common case here, everything should
-	 * be hot in cache, so would it be a big win?
-	 */
-	dentry = d_lookup(parent, name);
-	if (likely(!dentry)) {
-		dentry = d_alloc_and_lookup(parent, name, nd);
-		mutex_unlock(&dir->i_mutex);
-		if (IS_ERR(dentry))
-			goto fail;
-		goto done;
+static void terminate_walk(struct nameidata *nd)
+{
+	if (!(nd->flags & LOOKUP_RCU)) {
+		path_put(&nd->path);
+	} else {
+		nd->flags &= ~LOOKUP_RCU;
+		if (!(nd->flags & LOOKUP_ROOT))
+			nd->root.mnt = NULL;
+		rcu_read_unlock();
+		br_read_unlock(vfsmount_lock);
 	}
+}
+
+static inline int walk_component(struct nameidata *nd, struct path *path,
+		struct qstr *name, int type, int follow)
+{
+	struct inode *inode;
+	int err;
 	/*
-	 * Uhhuh! Nasty case: the cache was re-populated while
-	 * we waited on the semaphore. Need to revalidate.
+	 * "." and ".." are special - ".." especially so because it has
+	 * to be able to know about the current root directory and
+	 * parent relationships.
 	 */
-	mutex_unlock(&dir->i_mutex);
-	goto found;
+	if (unlikely(type != LAST_NORM))
+		return handle_dots(nd, type);
+	err = do_lookup(nd, name, path, &inode);
+	if (unlikely(err)) {
+		terminate_walk(nd);
+		return err;
+	}
+	if (!inode) {
+		path_to_nameidata(path, nd);
+		terminate_walk(nd);
+		return -ENOENT;
+	}
+	if (unlikely(inode->i_op->follow_link) && follow) {
+		if (nameidata_dentry_drop_rcu_maybe(nd, path->dentry))
+			return -ECHILD;
+		BUG_ON(inode != path->dentry->d_inode);
+		return 1;
+	}
+	path_to_nameidata(path, nd);
+	nd->inode = inode;
+	return 0;
+}
 
-fail:
-	return PTR_ERR(dentry);
+/*
+ * This limits recursive symlink follows to 8, while
+ * limiting consecutive symlinks to 40.
+ *
+ * Without that kind of total limit, nasty chains of consecutive
+ * symlinks can cause almost arbitrarily long lookups.
+ */
+static inline int nested_symlink(struct path *path, struct nameidata *nd)
+{
+	int res;
+
+	BUG_ON(nd->depth >= MAX_NESTED_LINKS);
+	if (unlikely(current->link_count >= MAX_NESTED_LINKS)) {
+		path_put_conditional(path, nd);
+		path_put(&nd->path);
+		return -ELOOP;
+	}
+
+	nd->depth++;
+	current->link_count++;
+
+	do {
+		struct path link = *path;
+		void *cookie;
+
+		res = follow_link(&link, nd, &cookie);
+		if (!res)
+			res = walk_component(nd, path, &nd->last,
+					     nd->last_type, LOOKUP_FOLLOW);
+		put_link(nd, &link, cookie);
+	} while (res > 0);
+
+	current->link_count--;
+	nd->depth--;
+	return res;
 }
 
 /*
@@ -1339,30 +1407,18 @@ static int link_path_walk(const char *name, struct nameidata *nd)
 	while (*name=='/')
 		name++;
 	if (!*name)
-		goto return_reval;
-
-	if (nd->depth)
-		lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE);
+		return 0;
 
 	/* At this point we know we have a real path component. */
 	for(;;) {
-		struct inode *inode;
 		unsigned long hash;
 		struct qstr this;
 		unsigned int c;
+		int type;
 
 		nd->flags |= LOOKUP_CONTINUE;
-		if (nd->flags & LOOKUP_RCU) {
-			err = exec_permission(nd->inode, IPERM_FLAG_RCU);
-			if (err == -ECHILD) {
-				if (nameidata_drop_rcu(nd))
-					return -ECHILD;
-				goto exec_again;
-			}
-		} else {
-exec_again:
-			err = exec_permission(nd->inode, 0);
-		}
+
+		err = may_lookup(nd);
  		if (err)
 			break;
 
@@ -1378,52 +1434,43 @@ exec_again:
 		this.len = name - (const char *) this.name;
 		this.hash = end_name_hash(hash);
 
+		type = LAST_NORM;
+		if (this.name[0] == '.') switch (this.len) {
+			case 2:
+				if (this.name[1] == '.') {
+					type = LAST_DOTDOT;
+					nd->flags |= LOOKUP_JUMPED;
+				}
+				break;
+			case 1:
+				type = LAST_DOT;
+		}
+		if (likely(type == LAST_NORM)) {
+			struct dentry *parent = nd->path.dentry;
+			nd->flags &= ~LOOKUP_JUMPED;
+			if (unlikely(parent->d_flags & DCACHE_OP_HASH)) {
+				err = parent->d_op->d_hash(parent, nd->inode,
+							   &this);
+				if (err < 0)
+					break;
+			}
+		}
+
 		/* remove trailing slashes? */
 		if (!c)
 			goto last_component;
 		while (*++name == '/');
 		if (!*name)
-			goto last_with_slashes;
+			goto last_component;
 
-		/*
-		 * "." and ".." are special - ".." especially so because it has
-		 * to be able to know about the current root directory and
-		 * parent relationships.
-		 */
-		if (this.name[0] == '.') switch (this.len) {
-			default:
-				break;
-			case 2:
-				if (this.name[1] != '.')
-					break;
-				if (nd->flags & LOOKUP_RCU) {
-					if (follow_dotdot_rcu(nd))
-						return -ECHILD;
-				} else
-					follow_dotdot(nd);
-				/* fallthrough */
-			case 1:
-				continue;
-		}
-		/* This does the actual lookups.. */
-		err = do_lookup(nd, &this, &next, &inode);
-		if (err)
-			break;
-		err = -ENOENT;
-		if (!inode)
-			goto out_dput;
+		err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW);
+		if (err < 0)
+			return err;
 
-		if (inode->i_op->follow_link) {
-			err = do_follow_link(inode, &next, nd);
+		if (err) {
+			err = nested_symlink(&next, nd);
 			if (err)
-				goto return_err;
-			nd->inode = nd->path.dentry->d_inode;
-			err = -ENOENT;
-			if (!nd->inode)
-				break;
-		} else {
-			path_to_nameidata(&next, nd);
-			nd->inode = inode;
+				return err;
 		}
 		err = -ENOTDIR; 
 		if (!nd->inode->i_op->lookup)
@@ -1431,209 +1478,109 @@ exec_again:
 		continue;
 		/* here ends the main loop */
 
-last_with_slashes:
-		lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
 last_component:
 		/* Clear LOOKUP_CONTINUE iff it was previously unset */
 		nd->flags &= lookup_flags | ~LOOKUP_CONTINUE;
-		if (lookup_flags & LOOKUP_PARENT)
-			goto lookup_parent;
-		if (this.name[0] == '.') switch (this.len) {
-			default:
-				break;
-			case 2:
-				if (this.name[1] != '.')
-					break;
-				if (nd->flags & LOOKUP_RCU) {
-					if (follow_dotdot_rcu(nd))
-						return -ECHILD;
-				} else
-					follow_dotdot(nd);
-				/* fallthrough */
-			case 1:
-				goto return_reval;
-		}
-		err = do_lookup(nd, &this, &next, &inode);
-		if (err)
-			break;
-		if (inode && unlikely(inode->i_op->follow_link) &&
-		    (lookup_flags & LOOKUP_FOLLOW)) {
-			err = do_follow_link(inode, &next, nd);
-			if (err)
-				goto return_err;
-			nd->inode = nd->path.dentry->d_inode;
-		} else {
-			path_to_nameidata(&next, nd);
-			nd->inode = inode;
-		}
-		err = -ENOENT;
-		if (!nd->inode)
-			break;
-		if (lookup_flags & LOOKUP_DIRECTORY) {
-			err = -ENOTDIR; 
-			if (!nd->inode->i_op->lookup)
-				break;
-		}
-		goto return_base;
-lookup_parent:
 		nd->last = this;
-		nd->last_type = LAST_NORM;
-		if (this.name[0] != '.')
-			goto return_base;
-		if (this.len == 1)
-			nd->last_type = LAST_DOT;
-		else if (this.len == 2 && this.name[1] == '.')
-			nd->last_type = LAST_DOTDOT;
-		else
-			goto return_base;
-return_reval:
-		/*
-		 * We bypassed the ordinary revalidation routines.
-		 * We may need to check the cached dentry for staleness.
-		 */
-		if (need_reval_dot(nd->path.dentry)) {
-			if (nameidata_drop_rcu_last_maybe(nd))
-				return -ECHILD;
-			/* Note: we do not d_invalidate() */
-			err = d_revalidate(nd->path.dentry, nd);
-			if (!err)
-				err = -ESTALE;
-			if (err < 0)
-				break;
-			return 0;
-		}
-return_base:
-		if (nameidata_drop_rcu_last_maybe(nd))
-			return -ECHILD;
+		nd->last_type = type;
 		return 0;
-out_dput:
-		if (!(nd->flags & LOOKUP_RCU))
-			path_put_conditional(&next, nd);
-		break;
 	}
-	if (!(nd->flags & LOOKUP_RCU))
-		path_put(&nd->path);
-return_err:
+	terminate_walk(nd);
 	return err;
 }
 
-static inline int path_walk_rcu(const char *name, struct nameidata *nd)
-{
-	current->total_link_count = 0;
-
-	return link_path_walk(name, nd);
-}
-
-static inline int path_walk_simple(const char *name, struct nameidata *nd)
-{
-	current->total_link_count = 0;
-
-	return link_path_walk(name, nd);
-}
-
-static int path_walk(const char *name, struct nameidata *nd)
-{
-	struct path save = nd->path;
-	int result;
-
-	current->total_link_count = 0;
-
-	/* make sure the stuff we saved doesn't go away */
-	path_get(&save);
-
-	result = link_path_walk(name, nd);
-	if (result == -ESTALE) {
-		/* nd->path had been dropped */
-		current->total_link_count = 0;
-		nd->path = save;
-		path_get(&nd->path);
-		nd->flags |= LOOKUP_REVAL;
-		result = link_path_walk(name, nd);
-	}
-
-	path_put(&save);
-
-	return result;
-}
-
-static void path_finish_rcu(struct nameidata *nd)
-{
-	if (nd->flags & LOOKUP_RCU) {
-		/* RCU dangling. Cancel it. */
-		nd->flags &= ~LOOKUP_RCU;
-		nd->root.mnt = NULL;
-		rcu_read_unlock();
-		br_read_unlock(vfsmount_lock);
-	}
-	if (nd->file)
-		fput(nd->file);
-}
-
-static int path_init_rcu(int dfd, const char *name, unsigned int flags, struct nameidata *nd)
+static int path_init(int dfd, const char *name, unsigned int flags,
+		     struct nameidata *nd, struct file **fp)
 {
 	int retval = 0;
 	int fput_needed;
 	struct file *file;
 
 	nd->last_type = LAST_ROOT; /* if there are only slashes... */
-	nd->flags = flags | LOOKUP_RCU;
+	nd->flags = flags | LOOKUP_JUMPED;
 	nd->depth = 0;
+	if (flags & LOOKUP_ROOT) {
+		struct inode *inode = nd->root.dentry->d_inode;
+		if (*name) {
+			if (!inode->i_op->lookup)
+				return -ENOTDIR;
+			retval = inode_permission(inode, MAY_EXEC);
+			if (retval)
+				return retval;
+		}
+		nd->path = nd->root;
+		nd->inode = inode;
+		if (flags & LOOKUP_RCU) {
+			br_read_lock(vfsmount_lock);
+			rcu_read_lock();
+			nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
+		} else {
+			path_get(&nd->path);
+		}
+		return 0;
+	}
+
 	nd->root.mnt = NULL;
-	nd->file = NULL;
 
 	if (*name=='/') {
-		struct fs_struct *fs = current->fs;
-		unsigned seq;
-
-		br_read_lock(vfsmount_lock);
-		rcu_read_lock();
-
-		do {
-			seq = read_seqcount_begin(&fs->seq);
-			nd->root = fs->root;
-			nd->path = nd->root;
-			nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
-		} while (read_seqcount_retry(&fs->seq, seq));
-
+		if (flags & LOOKUP_RCU) {
+			br_read_lock(vfsmount_lock);
+			rcu_read_lock();
+			set_root_rcu(nd);
+		} else {
+			set_root(nd);
+			path_get(&nd->root);
+		}
+		nd->path = nd->root;
 	} else if (dfd == AT_FDCWD) {
-		struct fs_struct *fs = current->fs;
-		unsigned seq;
+		if (flags & LOOKUP_RCU) {
+			struct fs_struct *fs = current->fs;
+			unsigned seq;
 
-		br_read_lock(vfsmount_lock);
-		rcu_read_lock();
-
-		do {
-			seq = read_seqcount_begin(&fs->seq);
-			nd->path = fs->pwd;
-			nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
-		} while (read_seqcount_retry(&fs->seq, seq));
+			br_read_lock(vfsmount_lock);
+			rcu_read_lock();
 
+			do {
+				seq = read_seqcount_begin(&fs->seq);
+				nd->path = fs->pwd;
+				nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
+			} while (read_seqcount_retry(&fs->seq, seq));
+		} else {
+			get_fs_pwd(current->fs, &nd->path);
+		}
 	} else {
 		struct dentry *dentry;
 
-		file = fget_light(dfd, &fput_needed);
+		file = fget_raw_light(dfd, &fput_needed);
 		retval = -EBADF;
 		if (!file)
 			goto out_fail;
 
 		dentry = file->f_path.dentry;
 
-		retval = -ENOTDIR;
-		if (!S_ISDIR(dentry->d_inode->i_mode))
-			goto fput_fail;
+		if (*name) {
+			retval = -ENOTDIR;
+			if (!S_ISDIR(dentry->d_inode->i_mode))
+				goto fput_fail;
 
-		retval = file_permission(file, MAY_EXEC);
-		if (retval)
-			goto fput_fail;
+			retval = file_permission(file, MAY_EXEC);
+			if (retval)
+				goto fput_fail;
+		}
 
 		nd->path = file->f_path;
-		if (fput_needed)
-			nd->file = file;
-
-		nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
-		br_read_lock(vfsmount_lock);
-		rcu_read_lock();
+		if (flags & LOOKUP_RCU) {
+			if (fput_needed)
+				*fp = file;
+			nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
+			br_read_lock(vfsmount_lock);
+			rcu_read_lock();
+		} else {
+			path_get(&file->f_path);
+			fput_light(file, fput_needed);
+		}
 	}
+
 	nd->inode = nd->path.dentry->d_inode;
 	return 0;
 
@@ -1643,60 +1590,23 @@ out_fail:
 	return retval;
 }
 
-static int path_init(int dfd, const char *name, unsigned int flags, struct nameidata *nd)
+static inline int lookup_last(struct nameidata *nd, struct path *path)
 {
-	int retval = 0;
-	int fput_needed;
-	struct file *file;
-
-	nd->last_type = LAST_ROOT; /* if there are only slashes... */
-	nd->flags = flags;
-	nd->depth = 0;
-	nd->root.mnt = NULL;
-
-	if (*name=='/') {
-		set_root(nd);
-		nd->path = nd->root;
-		path_get(&nd->root);
-	} else if (dfd == AT_FDCWD) {
-		get_fs_pwd(current->fs, &nd->path);
-	} else {
-		struct dentry *dentry;
-
-		file = fget_light(dfd, &fput_needed);
-		retval = -EBADF;
-		if (!file)
-			goto out_fail;
-
-		dentry = file->f_path.dentry;
-
-		retval = -ENOTDIR;
-		if (!S_ISDIR(dentry->d_inode->i_mode))
-			goto fput_fail;
-
-		retval = file_permission(file, MAY_EXEC);
-		if (retval)
-			goto fput_fail;
+	if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len])
+		nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
 
-		nd->path = file->f_path;
-		path_get(&file->f_path);
-
-		fput_light(file, fput_needed);
-	}
-	nd->inode = nd->path.dentry->d_inode;
-	return 0;
-
-fput_fail:
-	fput_light(file, fput_needed);
-out_fail:
-	return retval;
+	nd->flags &= ~LOOKUP_PARENT;
+	return walk_component(nd, path, &nd->last, nd->last_type,
+					nd->flags & LOOKUP_FOLLOW);
 }
 
 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
-static int do_path_lookup(int dfd, const char *name,
+static int path_lookupat(int dfd, const char *name,
 				unsigned int flags, struct nameidata *nd)
 {
-	int retval;
+	struct file *base = NULL;
+	struct path path;
+	int err;
 
 	/*
 	 * Path walking is largely split up into 2 different synchronisation
@@ -1712,44 +1622,78 @@ static int do_path_lookup(int dfd, const char *name,
 	 * be handled by restarting a traditional ref-walk (which will always
 	 * be able to complete).
 	 */
-	retval = path_init_rcu(dfd, name, flags, nd);
-	if (unlikely(retval))
-		return retval;
-	retval = path_walk_rcu(name, nd);
-	path_finish_rcu(nd);
-	if (nd->root.mnt) {
-		path_put(&nd->root);
-		nd->root.mnt = NULL;
+	err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base);
+
+	if (unlikely(err))
+		return err;
+
+	current->total_link_count = 0;
+	err = link_path_walk(name, nd);
+
+	if (!err && !(flags & LOOKUP_PARENT)) {
+		err = lookup_last(nd, &path);
+		while (err > 0) {
+			void *cookie;
+			struct path link = path;
+			nd->flags |= LOOKUP_PARENT;
+			err = follow_link(&link, nd, &cookie);
+			if (!err)
+				err = lookup_last(nd, &path);
+			put_link(nd, &link, cookie);
+		}
 	}
 
-	if (unlikely(retval == -ECHILD || retval == -ESTALE)) {
-		/* slower, locked walk */
-		if (retval == -ESTALE)
-			flags |= LOOKUP_REVAL;
-		retval = path_init(dfd, name, flags, nd);
-		if (unlikely(retval))
-			return retval;
-		retval = path_walk(name, nd);
-		if (nd->root.mnt) {
-			path_put(&nd->root);
-			nd->root.mnt = NULL;
+	if (nd->flags & LOOKUP_RCU) {
+		/* went all way through without dropping RCU */
+		BUG_ON(err);
+		if (nameidata_drop_rcu_last(nd))
+			err = -ECHILD;
+	}
+
+	if (!err) {
+		err = handle_reval_path(nd);
+		if (err)
+			path_put(&nd->path);
+	}
+
+	if (!err && nd->flags & LOOKUP_DIRECTORY) {
+		if (!nd->inode->i_op->lookup) {
+			path_put(&nd->path);
+			err = -ENOTDIR;
 		}
 	}
 
+	if (base)
+		fput(base);
+
+	if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
+		path_put(&nd->root);
+		nd->root.mnt = NULL;
+	}
+	return err;
+}
+
+static int do_path_lookup(int dfd, const char *name,
+				unsigned int flags, struct nameidata *nd)
+{
+	int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd);
+	if (unlikely(retval == -ECHILD))
+		retval = path_lookupat(dfd, name, flags, nd);
+	if (unlikely(retval == -ESTALE))
+		retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd);
+
 	if (likely(!retval)) {
 		if (unlikely(!audit_dummy_context())) {
 			if (nd->path.dentry && nd->inode)
 				audit_inode(name, nd->path.dentry);
 		}
 	}
-
 	return retval;
 }
 
-int path_lookup(const char *name, unsigned int flags,
-			struct nameidata *nd)
+int kern_path_parent(const char *name, struct nameidata *nd)
 {
-	return do_path_lookup(AT_FDCWD, name, flags, nd);
+	return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd);
 }
 
 int kern_path(const char *name, unsigned int flags, struct path *path)
@@ -1773,29 +1717,10 @@ int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
 		    const char *name, unsigned int flags,
 		    struct nameidata *nd)
 {
-	int retval;
-
-	/* same as do_path_lookup */
-	nd->last_type = LAST_ROOT;
-	nd->flags = flags;
-	nd->depth = 0;
-
-	nd->path.dentry = dentry;
-	nd->path.mnt = mnt;
-	path_get(&nd->path);
-	nd->root = nd->path;
-	path_get(&nd->root);
-	nd->inode = nd->path.dentry->d_inode;
-
-	retval = path_walk(name, nd);
-	if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry &&
-				nd->inode))
-		audit_inode(name, nd->path.dentry);
-
-	path_put(&nd->root);
-	nd->root.mnt = NULL;
-
-	return retval;
+	nd->root.dentry = dentry;
+	nd->root.mnt = mnt;
+	/* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */
+	return do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, nd);
 }
 
 static struct dentry *__lookup_hash(struct qstr *name,
@@ -1810,17 +1735,6 @@ static struct dentry *__lookup_hash(struct qstr *name,
 		return ERR_PTR(err);
 
 	/*
-	 * See if the low-level filesystem might want
-	 * to use its own hash..
-	 */
-	if (base->d_flags & DCACHE_OP_HASH) {
-		err = base->d_op->d_hash(base, inode, name);
-		dentry = ERR_PTR(err);
-		if (err < 0)
-			goto out;
-	}
-
-	/*
 	 * Don't bother with __d_lookup: callers are for creat as
 	 * well as unlink, so a lot of the time it would cost
 	 * a double lookup.
@@ -1832,7 +1746,7 @@ static struct dentry *__lookup_hash(struct qstr *name,
 
 	if (!dentry)
 		dentry = d_alloc_and_lookup(base, name, nd);
-out:
+
 	return dentry;
 }
 
@@ -1846,28 +1760,6 @@ static struct dentry *lookup_hash(struct nameidata *nd)
 	return __lookup_hash(&nd->last, nd->path.dentry, nd);
 }
 
-static int __lookup_one_len(const char *name, struct qstr *this,
-		struct dentry *base, int len)
-{
-	unsigned long hash;
-	unsigned int c;
-
-	this->name = name;
-	this->len = len;
-	if (!len)
-		return -EACCES;
-
-	hash = init_name_hash();
-	while (len--) {
-		c = *(const unsigned char *)name++;
-		if (c == '/' || c == '\0')
-			return -EACCES;
-		hash = partial_name_hash(c, hash);
-	}
-	this->hash = end_name_hash(hash);
-	return 0;
-}
-
 /**
  * lookup_one_len - filesystem helper to lookup single pathname component
  * @name:	pathname component to lookup
@@ -1881,14 +1773,34 @@ static int __lookup_one_len(const char *name, struct qstr *this,
  */
 struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
 {
-	int err;
 	struct qstr this;
+	unsigned long hash;
+	unsigned int c;
 
 	WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex));
 
-	err = __lookup_one_len(name, &this, base, len);
-	if (err)
-		return ERR_PTR(err);
+	this.name = name;
+	this.len = len;
+	if (!len)
+		return ERR_PTR(-EACCES);
+
+	hash = init_name_hash();
+	while (len--) {
+		c = *(const unsigned char *)name++;
+		if (c == '/' || c == '\0')
+			return ERR_PTR(-EACCES);
+		hash = partial_name_hash(c, hash);
+	}
+	this.hash = end_name_hash(hash);
+	/*
+	 * See if the low-level filesystem might want
+	 * to use its own hash..
+	 */
+	if (base->d_flags & DCACHE_OP_HASH) {
+		int err = base->d_op->d_hash(base, base->d_inode, &this);
+		if (err < 0)
+			return ERR_PTR(err);
+	}
 
 	return __lookup_hash(&this, base, NULL);
 }
@@ -1897,7 +1809,7 @@ int user_path_at(int dfd, const char __user *name, unsigned flags,
 		 struct path *path)
 {
 	struct nameidata nd;
-	char *tmp = getname(name);
+	char *tmp = getname_flags(name, flags);
 	int err = PTR_ERR(tmp);
 	if (!IS_ERR(tmp)) {
 
@@ -1939,11 +1851,15 @@ static inline int check_sticky(struct inode *dir, struct inode *inode)
 
 	if (!(dir->i_mode & S_ISVTX))
 		return 0;
+	if (current_user_ns() != inode_userns(inode))
+		goto other_userns;
 	if (inode->i_uid == fsuid)
 		return 0;
 	if (dir->i_uid == fsuid)
 		return 0;
-	return !capable(CAP_FOWNER);
+
+other_userns:
+	return !ns_capable(inode_userns(inode), CAP_FOWNER);
 }
 
 /*
@@ -2077,12 +1993,16 @@ int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
 	return error;
 }
 
-int may_open(struct path *path, int acc_mode, int flag)
+static int may_open(struct path *path, int acc_mode, int flag)
 {
 	struct dentry *dentry = path->dentry;
 	struct inode *inode = dentry->d_inode;
 	int error;
 
+	/* O_PATH? */
+	if (!acc_mode)
+		return 0;
+
 	if (!inode)
 		return -ENOENT;
 
@@ -2119,7 +2039,7 @@ int may_open(struct path *path, int acc_mode, int flag)
 	}
 
 	/* O_NOATIME can only be set by the owner or superuser */
-	if (flag & O_NOATIME && !is_owner_or_cap(inode))
+	if (flag & O_NOATIME && !inode_owner_or_capable(inode))
 		return -EPERM;
 
 	/*
@@ -2151,34 +2071,6 @@ static int handle_truncate(struct file *filp)
 }
 
 /*
- * Be careful about ever adding any more callers of this
- * function.  Its flags must be in the namei format, not
- * what get passed to sys_open().
- */
-static int __open_namei_create(struct nameidata *nd, struct path *path,
-				int open_flag, int mode)
-{
-	int error;
-	struct dentry *dir = nd->path.dentry;
-
-	if (!IS_POSIXACL(dir->d_inode))
-		mode &= ~current_umask();
-	error = security_path_mknod(&nd->path, path->dentry, mode, 0);
-	if (error)
-		goto out_unlock;
-	error = vfs_create(dir->d_inode, path->dentry, mode, nd);
-out_unlock:
-	mutex_unlock(&dir->d_inode->i_mutex);
-	dput(nd->path.dentry);
-	nd->path.dentry = path->dentry;
-
-	if (error)
-		return error;
-	/* Don't check for write permission, don't truncate */
-	return may_open(&nd->path, 0, open_flag & ~O_TRUNC);
-}
-
-/*
  * Note that while the flag value (low two bits) for sys_open means:
  *	00 - read-only
  *	01 - write-only
@@ -2202,126 +2094,115 @@ static inline int open_to_namei_flags(int flag)
 	return flag;
 }
 
-static int open_will_truncate(int flag, struct inode *inode)
-{
-	/*
-	 * We'll never write to the fs underlying
-	 * a device file.
-	 */
-	if (special_file(inode->i_mode))
-		return 0;
-	return (flag & O_TRUNC);
-}
-
-static struct file *finish_open(struct nameidata *nd,
-				int open_flag, int acc_mode)
-{
-	struct file *filp;
-	int will_truncate;
-	int error;
-
-	will_truncate = open_will_truncate(open_flag, nd->path.dentry->d_inode);
-	if (will_truncate) {
-		error = mnt_want_write(nd->path.mnt);
-		if (error)
-			goto exit;
-	}
-	error = may_open(&nd->path, acc_mode, open_flag);
-	if (error) {
-		if (will_truncate)
-			mnt_drop_write(nd->path.mnt);
-		goto exit;
-	}
-	filp = nameidata_to_filp(nd);
-	if (!IS_ERR(filp)) {
-		error = ima_file_check(filp, acc_mode);
-		if (error) {
-			fput(filp);
-			filp = ERR_PTR(error);
-		}
-	}
-	if (!IS_ERR(filp)) {
-		if (will_truncate) {
-			error = handle_truncate(filp);
-			if (error) {
-				fput(filp);
-				filp = ERR_PTR(error);
-			}
-		}
-	}
-	/*
-	 * It is now safe to drop the mnt write
-	 * because the filp has had a write taken
-	 * on its behalf.
-	 */
-	if (will_truncate)
-		mnt_drop_write(nd->path.mnt);
-	path_put(&nd->path);
-	return filp;
-
-exit:
-	path_put(&nd->path);
-	return ERR_PTR(error);
-}
-
 /*
- * Handle O_CREAT case for do_filp_open
+ * Handle the last step of open()
  */
 static struct file *do_last(struct nameidata *nd, struct path *path,
-			    int open_flag, int acc_mode,
-			    int mode, const char *pathname)
+			    const struct open_flags *op, const char *pathname)
 {
 	struct dentry *dir = nd->path.dentry;
+	struct dentry *dentry;
+	int open_flag = op->open_flag;
+	int will_truncate = open_flag & O_TRUNC;
+	int want_write = 0;
+	int acc_mode = op->acc_mode;
 	struct file *filp;
-	int error = -EISDIR;
+	int error;
+
+	nd->flags &= ~LOOKUP_PARENT;
+	nd->flags |= op->intent;
 
 	switch (nd->last_type) {
 	case LAST_DOTDOT:
-		follow_dotdot(nd);
-		dir = nd->path.dentry;
 	case LAST_DOT:
-		if (need_reval_dot(dir)) {
-			int status = d_revalidate(nd->path.dentry, nd);
-			if (!status)
-				status = -ESTALE;
-			if (status < 0) {
-				error = status;
-				goto exit;
-			}
-		}
+		error = handle_dots(nd, nd->last_type);
+		if (error)
+			return ERR_PTR(error);
 		/* fallthrough */
 	case LAST_ROOT:
-		goto exit;
+		if (nd->flags & LOOKUP_RCU) {
+			if (nameidata_drop_rcu_last(nd))
+				return ERR_PTR(-ECHILD);
+		}
+		error = handle_reval_path(nd);
+		if (error)
+			goto exit;
+		audit_inode(pathname, nd->path.dentry);
+		if (open_flag & O_CREAT) {
+			error = -EISDIR;
+			goto exit;
+		}
+		goto ok;
 	case LAST_BIND:
+		/* can't be RCU mode here */
+		error = handle_reval_path(nd);
+		if (error)
+			goto exit;
 		audit_inode(pathname, dir);
 		goto ok;
 	}
 
+	if (!(open_flag & O_CREAT)) {
+		int symlink_ok = 0;
+		if (nd->last.name[nd->last.len])
+			nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
+		if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW))
+			symlink_ok = 1;
+		/* we _can_ be in RCU mode here */
+		error = walk_component(nd, path, &nd->last, LAST_NORM,
+					!symlink_ok);
+		if (error < 0)
+			return ERR_PTR(error);
+		if (error) /* symlink */
+			return NULL;
+		/* sayonara */
+		if (nd->flags & LOOKUP_RCU) {
+			if (nameidata_drop_rcu_last(nd))
+				return ERR_PTR(-ECHILD);
+		}
+
+		error = -ENOTDIR;
+		if (nd->flags & LOOKUP_DIRECTORY) {
+			if (!nd->inode->i_op->lookup)
+				goto exit;
+		}
+		audit_inode(pathname, nd->path.dentry);
+		goto ok;
+	}
+
+	/* create side of things */
+
+	if (nd->flags & LOOKUP_RCU) {
+		if (nameidata_drop_rcu_last(nd))
+			return ERR_PTR(-ECHILD);
+	}
+
+	audit_inode(pathname, dir);
+	error = -EISDIR;
 	/* trailing slashes? */
 	if (nd->last.name[nd->last.len])
 		goto exit;
 
 	mutex_lock(&dir->d_inode->i_mutex);
 
-	path->dentry = lookup_hash(nd);
-	path->mnt = nd->path.mnt;
-
-	error = PTR_ERR(path->dentry);
-	if (IS_ERR(path->dentry)) {
+	dentry = lookup_hash(nd);
+	error = PTR_ERR(dentry);
+	if (IS_ERR(dentry)) {
 		mutex_unlock(&dir->d_inode->i_mutex);
 		goto exit;
 	}
 
-	if (IS_ERR(nd->intent.open.file)) {
-		error = PTR_ERR(nd->intent.open.file);
-		goto exit_mutex_unlock;
-	}
+	path->dentry = dentry;
+	path->mnt = nd->path.mnt;
 
 	/* Negative dentry, just create the file */
-	if (!path->dentry->d_inode) {
+	if (!dentry->d_inode) {
+		int mode = op->mode;
+		if (!IS_POSIXACL(dir->d_inode))
+			mode &= ~current_umask();
 		/*
 		 * This write is needed to ensure that a
-		 * ro->rw transition does not occur between
+		 * rw->ro transition does not occur between
 		 * the time when the file is created and when
 		 * a permanent write count is taken through
 		 * the 'struct file' in nameidata_to_filp().
@@ -2329,22 +2210,21 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
 		error = mnt_want_write(nd->path.mnt);
 		if (error)
 			goto exit_mutex_unlock;
-		error = __open_namei_create(nd, path, open_flag, mode);
-		if (error) {
-			mnt_drop_write(nd->path.mnt);
-			goto exit;
-		}
-		filp = nameidata_to_filp(nd);
-		mnt_drop_write(nd->path.mnt);
-		path_put(&nd->path);
-		if (!IS_ERR(filp)) {
-			error = ima_file_check(filp, acc_mode);
-			if (error) {
-				fput(filp);
-				filp = ERR_PTR(error);
-			}
-		}
-		return filp;
+		want_write = 1;
+		/* Don't check for write permission, don't truncate */
+		open_flag &= ~O_TRUNC;
+		will_truncate = 0;
+		acc_mode = MAY_OPEN;
+		error = security_path_mknod(&nd->path, dentry, mode, 0);
+		if (error)
+			goto exit_mutex_unlock;
+		error = vfs_create(dir->d_inode, dentry, mode, nd);
+		if (error)
+			goto exit_mutex_unlock;
+		mutex_unlock(&dir->d_inode->i_mutex);
+		dput(nd->path.dentry);
+		nd->path.dentry = dentry;
+		goto common;
 	}
 
 	/*
@@ -2374,7 +2254,40 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
 	if (S_ISDIR(nd->inode->i_mode))
 		goto exit;
 ok:
-	filp = finish_open(nd, open_flag, acc_mode);
+	if (!S_ISREG(nd->inode->i_mode))
+		will_truncate = 0;
+
+	if (will_truncate) {
+		error = mnt_want_write(nd->path.mnt);
+		if (error)
+			goto exit;
+		want_write = 1;
+	}
+common:
+	error = may_open(&nd->path, acc_mode, open_flag);
+	if (error)
+		goto exit;
+	filp = nameidata_to_filp(nd);
+	if (!IS_ERR(filp)) {
+		error = ima_file_check(filp, op->acc_mode);
+		if (error) {
+			fput(filp);
+			filp = ERR_PTR(error);
+		}
+	}
+	if (!IS_ERR(filp)) {
+		if (will_truncate) {
+			error = handle_truncate(filp);
+			if (error) {
+				fput(filp);
+				filp = ERR_PTR(error);
+			}
+		}
+	}
+out:
+	if (want_write)
+		mnt_drop_write(nd->path.mnt);
+	path_put(&nd->path);
 	return filp;
 
 exit_mutex_unlock:
@@ -2382,197 +2295,103 @@ exit_mutex_unlock:
 exit_dput:
 	path_put_conditional(path, nd);
 exit:
-	path_put(&nd->path);
-	return ERR_PTR(error);
+	filp = ERR_PTR(error);
+	goto out;
 }
 
-/*
- * Note that the low bits of the passed in "open_flag"
- * are not the same as in the local variable "flag". See
- * open_to_namei_flags() for more details.
- */
-struct file *do_filp_open(int dfd, const char *pathname,
-		int open_flag, int mode, int acc_mode)
+static struct file *path_openat(int dfd, const char *pathname,
+		struct nameidata *nd, const struct open_flags *op, int flags)
 {
+	struct file *base = NULL;
 	struct file *filp;
-	struct nameidata nd;
-	int error;
 	struct path path;
-	int count = 0;
-	int flag = open_to_namei_flags(open_flag);
-	int flags;
-
-	if (!(open_flag & O_CREAT))
-		mode = 0;
-
-	/* Must never be set by userspace */
-	open_flag &= ~FMODE_NONOTIFY;
-
-	/*
-	 * O_SYNC is implemented as __O_SYNC|O_DSYNC.  As many places only
-	 * check for O_DSYNC if the need any syncing at all we enforce it's
-	 * always set instead of having to deal with possibly weird behaviour
-	 * for malicious applications setting only __O_SYNC.
-	 */
-	if (open_flag & __O_SYNC)
-		open_flag |= O_DSYNC;
-
-	if (!acc_mode)
-		acc_mode = MAY_OPEN | ACC_MODE(open_flag);
-
-	/* O_TRUNC implies we need access checks for write permissions */
-	if (open_flag & O_TRUNC)
-		acc_mode |= MAY_WRITE;
-
-	/* Allow the LSM permission hook to distinguish append 
-	   access from general write access. */
-	if (open_flag & O_APPEND)
-		acc_mode |= MAY_APPEND;
-
-	flags = LOOKUP_OPEN;
-	if (open_flag & O_CREAT) {
-		flags |= LOOKUP_CREATE;
-		if (open_flag & O_EXCL)
-			flags |= LOOKUP_EXCL;
-	}
-	if (open_flag & O_DIRECTORY)
-		flags |= LOOKUP_DIRECTORY;
-	if (!(open_flag & O_NOFOLLOW))
-		flags |= LOOKUP_FOLLOW;
+	int error;
 
 	filp = get_empty_filp();
 	if (!filp)
 		return ERR_PTR(-ENFILE);
 
-	filp->f_flags = open_flag;
-	nd.intent.open.file = filp;
-	nd.intent.open.flags = flag;
-	nd.intent.open.create_mode = mode;
+	filp->f_flags = op->open_flag;
+	nd->intent.open.file = filp;
+	nd->intent.open.flags = open_to_namei_flags(op->open_flag);
+	nd->intent.open.create_mode = op->mode;
 
-	if (open_flag & O_CREAT)
-		goto creat;
-
-	/* !O_CREAT, simple open */
-	error = do_path_lookup(dfd, pathname, flags, &nd);
+	error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base);
 	if (unlikely(error))
 		goto out_filp;
-	error = -ELOOP;
-	if (!(nd.flags & LOOKUP_FOLLOW)) {
-		if (nd.inode->i_op->follow_link)
-			goto out_path;
-	}
-	error = -ENOTDIR;
-	if (nd.flags & LOOKUP_DIRECTORY) {
-		if (!nd.inode->i_op->lookup)
-			goto out_path;
-	}
-	audit_inode(pathname, nd.path.dentry);
-	filp = finish_open(&nd, open_flag, acc_mode);
-	release_open_intent(&nd);
-	return filp;
-
-creat:
-	/* OK, have to create the file. Find the parent. */
-	error = path_init_rcu(dfd, pathname,
-			LOOKUP_PARENT | (flags & LOOKUP_REVAL), &nd);
-	if (error)
-		goto out_filp;
-	error = path_walk_rcu(pathname, &nd);
-	path_finish_rcu(&nd);
-	if (unlikely(error == -ECHILD || error == -ESTALE)) {
-		/* slower, locked walk */
-		if (error == -ESTALE) {
-reval:
-			flags |= LOOKUP_REVAL;
-		}
-		error = path_init(dfd, pathname,
-				LOOKUP_PARENT | (flags & LOOKUP_REVAL), &nd);
-		if (error)
-			goto out_filp;
 
-		error = path_walk_simple(pathname, &nd);
-	}
+	current->total_link_count = 0;
+	error = link_path_walk(pathname, nd);
 	if (unlikely(error))
 		goto out_filp;
-	if (unlikely(!audit_dummy_context()))
-		audit_inode(pathname, nd.path.dentry);
 
-	/*
-	 * We have the parent and last component.
-	 */
-	nd.flags = flags;
-	filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname);
+	filp = do_last(nd, &path, op, pathname);
 	while (unlikely(!filp)) { /* trailing symlink */
 		struct path link = path;
-		struct inode *linki = link.dentry->d_inode;
 		void *cookie;
-		error = -ELOOP;
-		if (!(nd.flags & LOOKUP_FOLLOW))
-			goto exit_dput;
-		if (count++ == 32)
-			goto exit_dput;
-		/*
-		 * This is subtle. Instead of calling do_follow_link() we do
-		 * the thing by hands. The reason is that this way we have zero
-		 * link_count and path_walk() (called from ->follow_link)
-		 * honoring LOOKUP_PARENT.  After that we have the parent and
-		 * last component, i.e. we are in the same situation as after
-		 * the first path_walk().  Well, almost - if the last component
-		 * is normal we get its copy stored in nd->last.name and we will
-		 * have to putname() it when we are done. Procfs-like symlinks
-		 * just set LAST_BIND.
-		 */
-		nd.flags |= LOOKUP_PARENT;
-		error = security_inode_follow_link(link.dentry, &nd);
-		if (error)
-			goto exit_dput;
-		error = __do_follow_link(&link, &nd, &cookie);
-		if (unlikely(error)) {
-			if (!IS_ERR(cookie) && linki->i_op->put_link)
-				linki->i_op->put_link(link.dentry, &nd, cookie);
-			/* nd.path had been dropped */
-			nd.path = link;
-			goto out_path;
+		if (!(nd->flags & LOOKUP_FOLLOW)) {
+			path_put_conditional(&path, nd);
+			path_put(&nd->path);
+			filp = ERR_PTR(-ELOOP);
+			break;
 		}
-		nd.flags &= ~LOOKUP_PARENT;
-		filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname);
-		if (linki->i_op->put_link)
-			linki->i_op->put_link(link.dentry, &nd, cookie);
-		path_put(&link);
+		nd->flags |= LOOKUP_PARENT;
+		nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
+		error = follow_link(&link, nd, &cookie);
+		if (unlikely(error))
+			filp = ERR_PTR(error);
+		else
+			filp = do_last(nd, &path, op, pathname);
+		put_link(nd, &link, cookie);
 	}
 out:
-	if (nd.root.mnt)
-		path_put(&nd.root);
-	if (filp == ERR_PTR(-ESTALE) && !(flags & LOOKUP_REVAL))
-		goto reval;
-	release_open_intent(&nd);
+	if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT))
+		path_put(&nd->root);
+	if (base)
+		fput(base);
+	release_open_intent(nd);
 	return filp;
 
-exit_dput:
-	path_put_conditional(&path, &nd);
-out_path:
-	path_put(&nd.path);
 out_filp:
 	filp = ERR_PTR(error);
 	goto out;
 }
 
-/**
- * filp_open - open file and return file pointer
- *
- * @filename:	path to open
- * @flags:	open flags as per the open(2) second argument
- * @mode:	mode for the new file if O_CREAT is set, else ignored
- *
- * This is the helper to open a file from kernelspace if you really
- * have to.  But in generally you should not do this, so please move
- * along, nothing to see here..
- */
-struct file *filp_open(const char *filename, int flags, int mode)
+struct file *do_filp_open(int dfd, const char *pathname,
+		const struct open_flags *op, int flags)
 {
-	return do_filp_open(AT_FDCWD, filename, flags, mode, 0);
+	struct nameidata nd;
+	struct file *filp;
+
+	filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU);
+	if (unlikely(filp == ERR_PTR(-ECHILD)))
+		filp = path_openat(dfd, pathname, &nd, op, flags);
+	if (unlikely(filp == ERR_PTR(-ESTALE)))
+		filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL);
+	return filp;
+}
+
+struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
+		const char *name, const struct open_flags *op, int flags)
+{
+	struct nameidata nd;
+	struct file *file;
+
+	nd.root.mnt = mnt;
+	nd.root.dentry = dentry;
+
+	flags |= LOOKUP_ROOT;
+
+	if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN)
+		return ERR_PTR(-ELOOP);
+
+	file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU);
+	if (unlikely(file == ERR_PTR(-ECHILD)))
+		file = path_openat(-1, name, &nd, op, flags);
+	if (unlikely(file == ERR_PTR(-ESTALE)))
+		file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL);
+	return file;
 }
-EXPORT_SYMBOL(filp_open);
 
 /**
  * lookup_create - lookup a dentry, creating it if it doesn't exist
@@ -2634,7 +2453,8 @@ int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
 	if (error)
 		return error;
 
-	if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
+	if ((S_ISCHR(mode) || S_ISBLK(mode)) &&
+	    !ns_capable(inode_userns(dir), CAP_MKNOD))
 		return -EPERM;
 
 	if (!dir->i_op->mknod)
@@ -3111,7 +2931,11 @@ int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_de
 		return error;
 
 	mutex_lock(&inode->i_mutex);
-	error = dir->i_op->link(old_dentry, dir, new_dentry);
+	/* Make sure we don't allow creating hardlink to an unlinked file */
+	if (inode->i_nlink == 0)
+		error =  -ENOENT;
+	else
+		error = dir->i_op->link(old_dentry, dir, new_dentry);
 	mutex_unlock(&inode->i_mutex);
 	if (!error)
 		fsnotify_link(dir, inode, new_dentry);
@@ -3133,15 +2957,27 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
 	struct dentry *new_dentry;
 	struct nameidata nd;
 	struct path old_path;
+	int how = 0;
 	int error;
 	char *to;
 
-	if ((flags & ~AT_SYMLINK_FOLLOW) != 0)
+	if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0)
 		return -EINVAL;
+	/*
+	 * To use null names we require CAP_DAC_READ_SEARCH
+	 * This ensures that not everyone will be able to create
+	 * handlink using the passed filedescriptor.
+	 */
+	if (flags & AT_EMPTY_PATH) {
+		if (!capable(CAP_DAC_READ_SEARCH))
+			return -ENOENT;
+		how = LOOKUP_EMPTY;
+	}
+
+	if (flags & AT_SYMLINK_FOLLOW)
+		how |= LOOKUP_FOLLOW;
 
-	error = user_path_at(olddfd, oldname,
-			     flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0,
-			     &old_path);
+	error = user_path_at(olddfd, oldname, how, &old_path);
 	if (error)
 		return error;
 
@@ -3578,7 +3414,7 @@ EXPORT_SYMBOL(page_readlink);
 EXPORT_SYMBOL(__page_symlink);
 EXPORT_SYMBOL(page_symlink);
 EXPORT_SYMBOL(page_symlink_inode_operations);
-EXPORT_SYMBOL(path_lookup);
+EXPORT_SYMBOL(kern_path_parent);
 EXPORT_SYMBOL(kern_path);
 EXPORT_SYMBOL(vfs_path_lookup);
 EXPORT_SYMBOL(inode_permission);