1 files changed, 106 insertions, 28 deletions

diff --git a/kernel/fs/overlayfs/super.c b/kernel/fs/overlayfs/super.c
index 155989455..000b2ed05 100644
--- a/kernel/fs/overlayfs/super.c
+++ b/kernel/fs/overlayfs/super.c
@@ -9,6 +9,7 @@
 
 #include <linux/fs.h>
 #include <linux/namei.h>
+#include <linux/pagemap.h>
 #include <linux/xattr.h>
 #include <linux/security.h>
 #include <linux/mount.h>
@@ -75,12 +76,14 @@ enum ovl_path_type ovl_path_type(struct dentry *dentry)
 	if (oe->__upperdentry) {
 		type = __OVL_PATH_UPPER;
 
-		if (oe->numlower) {
-			if (S_ISDIR(dentry->d_inode->i_mode))
-				type |= __OVL_PATH_MERGE;
-		} else if (!oe->opaque) {
+		/*
+		 * Non-dir dentry can hold lower dentry from previous
+		 * location. Its purity depends only on opaque flag.
+		 */
+		if (oe->numlower && S_ISDIR(dentry->d_inode->i_mode))
+			type |= __OVL_PATH_MERGE;
+		else if (!oe->opaque)
 			type |= __OVL_PATH_PURE;
-		}
 	} else {
 		if (oe->numlower > 1)
 			type |= __OVL_PATH_MERGE;
@@ -273,8 +276,57 @@ static void ovl_dentry_release(struct dentry *dentry)
 	}
 }
 
+static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags)
+{
+	struct ovl_entry *oe = dentry->d_fsdata;
+	unsigned int i;
+	int ret = 1;
+
+	for (i = 0; i < oe->numlower; i++) {
+		struct dentry *d = oe->lowerstack[i].dentry;
+
+		if (d->d_flags & DCACHE_OP_REVALIDATE) {
+			ret = d->d_op->d_revalidate(d, flags);
+			if (ret < 0)
+				return ret;
+			if (!ret) {
+				if (!(flags & LOOKUP_RCU))
+					d_invalidate(d);
+				return -ESTALE;
+			}
+		}
+	}
+	return 1;
+}
+
+static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags)
+{
+	struct ovl_entry *oe = dentry->d_fsdata;
+	unsigned int i;
+	int ret = 1;
+
+	for (i = 0; i < oe->numlower; i++) {
+		struct dentry *d = oe->lowerstack[i].dentry;
+
+		if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) {
+			ret = d->d_op->d_weak_revalidate(d, flags);
+			if (ret <= 0)
+				break;
+		}
+	}
+	return ret;
+}
+
 static const struct dentry_operations ovl_dentry_operations = {
 	.d_release = ovl_dentry_release,
+	.d_select_inode = ovl_d_select_inode,
+};
+
+static const struct dentry_operations ovl_reval_dentry_operations = {
+	.d_release = ovl_dentry_release,
+	.d_select_inode = ovl_d_select_inode,
+	.d_revalidate = ovl_dentry_revalidate,
+	.d_weak_revalidate = ovl_dentry_weak_revalidate,
 };
 
 static struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
@@ -288,6 +340,20 @@ static struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
 	return oe;
 }
 
+static bool ovl_dentry_remote(struct dentry *dentry)
+{
+	return dentry->d_flags &
+		(DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
+}
+
+static bool ovl_dentry_weird(struct dentry *dentry)
+{
+	return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
+				  DCACHE_MANAGE_TRANSIT |
+				  DCACHE_OP_HASH |
+				  DCACHE_OP_COMPARE);
+}
+
 static inline struct dentry *ovl_lookup_real(struct dentry *dir,
 					     struct qstr *name)
 {
@@ -303,6 +369,10 @@ static inline struct dentry *ovl_lookup_real(struct dentry *dir,
 	} else if (!dentry->d_inode) {
 		dput(dentry);
 		dentry = NULL;
+	} else if (ovl_dentry_weird(dentry)) {
+		dput(dentry);
+		/* Don't support traversing automounts and other weirdness */
+		dentry = ERR_PTR(-EREMOTE);
 	}
 	return dentry;
 }
@@ -350,6 +420,11 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 			goto out;
 
 		if (this) {
+			if (unlikely(ovl_dentry_remote(this))) {
+				dput(this);
+				err = -EREMOTE;
+				goto out;
+			}
 			if (ovl_is_whiteout(this)) {
 				dput(this);
 				this = NULL;
@@ -473,6 +548,7 @@ static void ovl_put_super(struct super_block *sb)
 	mntput(ufs->upper_mnt);
 	for (i = 0; i < ufs->numlower; i++)
 		mntput(ufs->lower_mnt[i]);
+	kfree(ufs->lower_mnt);
 
 	kfree(ufs->config.lowerdir);
 	kfree(ufs->config.upperdir);
@@ -694,25 +770,6 @@ static void ovl_unescape(char *s)
 	}
 }
 
-static bool ovl_is_allowed_fs_type(struct dentry *root)
-{
-	const struct dentry_operations *dop = root->d_op;
-
-	/*
-	 * We don't support:
-	 *  - automount filesystems
-	 *  - filesystems with revalidate (FIXME for lower layer)
-	 *  - filesystems with case insensitive names
-	 */
-	if (dop &&
-	    (dop->d_manage || dop->d_automount ||
-	     dop->d_revalidate || dop->d_weak_revalidate ||
-	     dop->d_compare || dop->d_hash)) {
-		return false;
-	}
-	return true;
-}
-
 static int ovl_mount_dir_noesc(const char *name, struct path *path)
 {
 	int err = -EINVAL;
@@ -727,7 +784,7 @@ static int ovl_mount_dir_noesc(const char *name, struct path *path)
 		goto out;
 	}
 	err = -EINVAL;
-	if (!ovl_is_allowed_fs_type(path->dentry)) {
+	if (ovl_dentry_weird(path->dentry)) {
 		pr_err("overlayfs: filesystem on '%s' not supported\n", name);
 		goto out_put;
 	}
@@ -751,13 +808,21 @@ static int ovl_mount_dir(const char *name, struct path *path)
 	if (tmp) {
 		ovl_unescape(tmp);
 		err = ovl_mount_dir_noesc(tmp, path);
+
+		if (!err)
+			if (ovl_dentry_remote(path->dentry)) {
+				pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n",
+				       tmp);
+				path_put(path);
+				err = -EINVAL;
+			}
 		kfree(tmp);
 	}
 	return err;
 }
 
 static int ovl_lower_dir(const char *name, struct path *path, long *namelen,
-			 int *stack_depth)
+			 int *stack_depth, bool *remote)
 {
 	int err;
 	struct kstatfs statfs;
@@ -774,6 +839,9 @@ static int ovl_lower_dir(const char *name, struct path *path, long *namelen,
 	*namelen = max(*namelen, statfs.f_namelen);
 	*stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
 
+	if (ovl_dentry_remote(path->dentry))
+		*remote = true;
+
 	return 0;
 
 out_put:
@@ -827,6 +895,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 	unsigned int numlower;
 	unsigned int stacklen = 0;
 	unsigned int i;
+	bool remote = false;
 	int err;
 
 	err = -ENOMEM;
@@ -845,6 +914,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 	}
 
 	sb->s_stack_depth = 0;
+	sb->s_maxbytes = MAX_LFS_FILESIZE;
 	if (ufs->config.upperdir) {
 		if (!ufs->config.workdir) {
 			pr_err("overlayfs: missing 'workdir'\n");
@@ -900,7 +970,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 	lower = lowertmp;
 	for (numlower = 0; numlower < stacklen; numlower++) {
 		err = ovl_lower_dir(lower, &stack[numlower],
-				    &ufs->lower_namelen, &sb->s_stack_depth);
+				    &ufs->lower_namelen, &sb->s_stack_depth,
+				    &remote);
 		if (err)
 			goto out_put_lowerpath;
 
@@ -958,7 +1029,10 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 	if (!ufs->upper_mnt)
 		sb->s_flags |= MS_RDONLY;
 
-	sb->s_d_op = &ovl_dentry_operations;
+	if (remote)
+		sb->s_d_op = &ovl_reval_dentry_operations;
+	else
+		sb->s_d_op = &ovl_dentry_operations;
 
 	err = -ENOMEM;
 	oe = ovl_alloc_entry(numlower);
@@ -980,9 +1054,13 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 		oe->lowerstack[i].dentry = stack[i].dentry;
 		oe->lowerstack[i].mnt = ufs->lower_mnt[i];
 	}
+	kfree(stack);
 
 	root_dentry->d_fsdata = oe;
 
+	ovl_copyattr(ovl_dentry_real(root_dentry)->d_inode,
+		     root_dentry->d_inode);
+
 	sb->s_magic = OVERLAYFS_SUPER_MAGIC;
 	sb->s_op = &ovl_super_operations;
 	sb->s_root = root_dentry;