X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=fs%2Fnamei.c;h=2c226559c637e4f16f693b9aef040fc73feef1f5;hb=11fbe69aa25a787aa3f3dea5dad9eb4f6944bc70;hp=ac6d214da82790a8f16671e59dfffaf49e4c75bd;hpb=5c24d8b2bf99ee93049a6f8154ef9cd7897a6e36;p=pandora-kernel.git

diff --git a/fs/namei.c b/fs/namei.c
index ac6d214da827..2c226559c637 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -398,6 +398,24 @@ void path_put(struct path *path)
 }
 EXPORT_SYMBOL(path_put);
 
+/**
+ * path_connected - Verify that a path->dentry is below path->mnt.mnt_root
+ * @path: nameidate to verify
+ *
+ * Rename can sometimes move a file or directory outside of a bind
+ * mount, path_connected allows those cases to be detected.
+ */
+static bool path_connected(const struct path *path)
+{
+	struct vfsmount *mnt = path->mnt;
+
+	/* Only bind mounts can have disconnected paths */
+	if (mnt->mnt_root == mnt->mnt_sb->s_root)
+		return true;
+
+	return is_subdir(path->dentry, mnt->mnt_root);
+}
+
 /*
  * Path walking has 2 modes, rcu-walk and ref-walk (see
  * Documentation/filesystems/path-lookup.txt).  In situations when we can't
@@ -554,24 +572,22 @@ static int complete_walk(struct nameidata *nd)
 
 static __always_inline void set_root(struct nameidata *nd)
 {
-	if (!nd->root.mnt)
-		get_fs_root(current->fs, &nd->root);
+	get_fs_root(current->fs, &nd->root);
 }
 
 static int link_path_walk(const char *, struct nameidata *);
 
-static __always_inline void set_root_rcu(struct nameidata *nd)
+static __always_inline unsigned set_root_rcu(struct nameidata *nd)
 {
-	if (!nd->root.mnt) {
-		struct fs_struct *fs = current->fs;
-		unsigned seq;
+	struct fs_struct *fs = current->fs;
+	unsigned seq, res;
 
-		do {
-			seq = read_seqcount_begin(&fs->seq);
-			nd->root = fs->root;
-			nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
-		} while (read_seqcount_retry(&fs->seq, seq));
-	}
+	do {
+		seq = read_seqcount_begin(&fs->seq);
+		nd->root = fs->root;
+		res = __read_seqcount_begin(&nd->root.dentry->d_seq);
+	} while (read_seqcount_retry(&fs->seq, seq));
+	return res;
 }
 
 static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
@@ -582,7 +598,8 @@ static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *l
 		goto fail;
 
 	if (*link == '/') {
-		set_root(nd);
+		if (!nd->root.mnt)
+			set_root(nd);
 		path_put(&nd->path);
 		nd->path = nd->root;
 		path_get(&nd->root);
@@ -852,7 +869,7 @@ static int follow_managed(struct path *path, unsigned flags)
 		mntput(path->mnt);
 	if (ret == -EISDIR)
 		ret = 0;
-	return ret;
+	return ret < 0 ? ret : need_mntput;
 }
 
 int follow_down_one(struct path *path)
@@ -900,6 +917,7 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
 			break;
 		path->mnt = mounted;
 		path->dentry = mounted->mnt_root;
+		nd->flags |= LOOKUP_JUMPED;
 		nd->seq = read_seqcount_begin(&path->dentry->d_seq);
 		/*
 		 * Update the inode too. We don't need to re-check the
@@ -911,22 +929,11 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
 	return true;
 }
 
-static void follow_mount_rcu(struct nameidata *nd)
-{
-	while (d_mountpoint(nd->path.dentry)) {
-		struct vfsmount *mounted;
-		mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1);
-		if (!mounted)
-			break;
-		nd->path.mnt = mounted;
-		nd->path.dentry = mounted->mnt_root;
-		nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
-	}
-}
-
 static int follow_dotdot_rcu(struct nameidata *nd)
 {
-	set_root_rcu(nd);
+	struct inode *inode = nd->inode;
+	if (!nd->root.mnt)
+		set_root_rcu(nd);
 
 	while (1) {
 		if (nd->path.dentry == nd->root.dentry &&
@@ -938,19 +945,32 @@ static int follow_dotdot_rcu(struct nameidata *nd)
 			struct dentry *parent = old->d_parent;
 			unsigned seq;
 
+			inode = parent->d_inode;
 			seq = read_seqcount_begin(&parent->d_seq);
 			if (read_seqcount_retry(&old->d_seq, nd->seq))
 				goto failed;
 			nd->path.dentry = parent;
 			nd->seq = seq;
+			if (unlikely(!path_connected(&nd->path)))
+				goto failed;
 			break;
 		}
 		if (!follow_up_rcu(&nd->path))
 			break;
+		inode = nd->path.dentry->d_inode;
 		nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
 	}
-	follow_mount_rcu(nd);
-	nd->inode = nd->path.dentry->d_inode;
+	while (d_mountpoint(nd->path.dentry)) {
+		struct vfsmount *mounted;
+		mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1);
+		if (!mounted)
+			break;
+		nd->path.mnt = mounted;
+		nd->path.dentry = mounted->mnt_root;
+		inode = nd->path.dentry->d_inode;
+		nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
+	}
+	nd->inode = inode;
 	return 0;
 
 failed:
@@ -1027,9 +1047,10 @@ static void follow_mount(struct path *path)
 	}
 }
 
-static void follow_dotdot(struct nameidata *nd)
+static int follow_dotdot(struct nameidata *nd)
 {
-	set_root(nd);
+	if (!nd->root.mnt)
+		set_root(nd);
 
 	while(1) {
 		struct dentry *old = nd->path.dentry;
@@ -1042,6 +1063,10 @@ static void follow_dotdot(struct nameidata *nd)
 			/* rare case of legitimate dget_parent()... */
 			nd->path.dentry = dget_parent(nd->path.dentry);
 			dput(old);
+			if (unlikely(!path_connected(&nd->path))) {
+				path_put(&nd->path);
+				return -ENOENT;
+			}
 			break;
 		}
 		if (!follow_up(&nd->path))
@@ -1049,6 +1074,7 @@ static void follow_dotdot(struct nameidata *nd)
 	}
 	follow_mount(&nd->path);
 	nd->inode = nd->path.dentry->d_inode;
+	return 0;
 }
 
 /*
@@ -1093,8 +1119,10 @@ static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentr
 	struct dentry *old;
 
 	/* Don't create child dentry for a dead directory. */
-	if (unlikely(IS_DEADDIR(inode)))
+	if (unlikely(IS_DEADDIR(inode))) {
+		dput(dentry);
 		return ERR_PTR(-ENOENT);
+	}
 
 	old = inode->i_op->lookup(inode, dentry, nd);
 	if (unlikely(old)) {
@@ -1213,6 +1241,8 @@ retry:
 		path_put_conditional(path, nd);
 		return err;
 	}
+	if (err)
+		nd->flags |= LOOKUP_JUMPED;
 	*inode = path->dentry->d_inode;
 	return 0;
 }
@@ -1236,7 +1266,7 @@ static inline int handle_dots(struct nameidata *nd, int type)
 			if (follow_dotdot_rcu(nd))
 				return -ECHILD;
 		} else
-			follow_dotdot(nd);
+			return follow_dotdot(nd);
 	}
 	return 0;
 }
@@ -1499,7 +1529,7 @@ static int path_init(int dfd, const char *name, unsigned int flags,
 		if (flags & LOOKUP_RCU) {
 			br_read_lock(vfsmount_lock);
 			rcu_read_lock();
-			set_root_rcu(nd);
+			nd->seq = set_root_rcu(nd);
 		} else {
 			set_root(nd);
 			path_get(&nd->root);
@@ -1555,7 +1585,15 @@ static int path_init(int dfd, const char *name, unsigned int flags,
 	}
 
 	nd->inode = nd->path.dentry->d_inode;
-	return 0;
+	if (!(flags & LOOKUP_RCU))
+		return 0;
+	if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq)))
+		return 0;
+	if (!(nd->flags & LOOKUP_ROOT))
+		nd->root.mnt = NULL;
+	rcu_read_unlock();
+	br_read_unlock(vfsmount_lock);
+	return -ECHILD;
 
 fput_fail:
 	fput_light(file, fput_needed);
@@ -2134,7 +2172,7 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
 		/* sayonara */
 		error = complete_walk(nd);
 		if (error)
-			return ERR_PTR(-ECHILD);
+			return ERR_PTR(error);
 
 		error = -ENOTDIR;
 		if (nd->flags & LOOKUP_DIRECTORY) {
@@ -2146,6 +2184,10 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
 	}
 
 	/* create side of things */
+	/*
+	 * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED has been
+	 * cleared when we got to the last component we are about to look up
+	 */
 	error = complete_walk(nd);
 	if (error)
 		return ERR_PTR(error);
@@ -2214,6 +2256,9 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
 	if (error < 0)
 		goto exit_dput;
 
+	if (error)
+		nd->flags |= LOOKUP_JUMPED;
+
 	error = -ENOENT;
 	if (!path->dentry->d_inode)
 		goto exit_dput;
@@ -2223,6 +2268,10 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
 
 	path_to_nameidata(path, nd);
 	nd->inode = path->dentry->d_inode;
+	/* Why this, you ask?  _Now_ we might have grown LOOKUP_JUMPED... */
+	error = complete_walk(nd);
+	if (error)
+		return ERR_PTR(error);
 	error = -EISDIR;
 	if (S_ISDIR(nd->inode->i_mode))
 		goto exit;