diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 23d64d51f331b68464fd0cdac207a1b1b5510abf..35bb956af8e8a2e1c0aa13d66ada81458774cf3b 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -96,11 +96,15 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
WARN_ON_ONCE(stat->dev != lowerstat.dev);
/*
- * Lower hardlinks are broken on copy up to different
+ * Lower hardlinks may be broken on copy up to different
* upper files, so we cannot use the lower origin st_ino
* for those different files, even for the same fs case.
+ * With inodes index enabled, it is safe to use st_ino
+ * of an indexed hardlinked origin. The index validates
+ * that the upper hardlink is not broken.
*/
- if (is_dir || lowerstat.nlink == 1)
+ if (is_dir || lowerstat.nlink == 1 ||
+ ovl_test_flag(OVL_INDEX, d_inode(dentry)))
stat->ino = lowerstat.ino;
}
stat->dev = dentry->d_sb->s_dev;
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index 0c816e9aa50c0337cf434da61bd1b192dbe4a06e..3bec4cb39967804450504bb3da85339a9efebe09 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -378,6 +378,94 @@ int ovl_verify_origin(struct dentry *dentry, struct vfsmount *mnt,
goto out;
}
+/*
+ * Lookup in indexdir for the index entry of a lower real inode or a copy up
+ * origin inode. The index entry name is the hex representation of the lower
+ * inode file handle.
+ *
+ * If the index dentry in negative, then either no lower aliases have been
+ * copied up yet, or aliases have been copied up in older kernels and are
+ * not indexed.
+ *
+ * If the index dentry for a copy up origin inode is positive, but points
+ * to an inode different than the upper inode, then either the upper inode
+ * has been copied up and not indexed or it was indexed, but since then
+ * index dir was cleared. Either way, that index cannot be used to indentify
+ * the overlay inode.
+ */
+int ovl_get_index_name(struct dentry *origin, struct qstr *name)
+{
+ int err;
+ struct ovl_fh *fh;
+ char *n, *s;
+
+ fh = ovl_encode_fh(origin, false);
+ if (IS_ERR(fh))
+ return PTR_ERR(fh);
+
+ err = -ENOMEM;
+ n = kzalloc(fh->len * 2, GFP_TEMPORARY);
+ if (n) {
+ s = bin2hex(n, fh, fh->len);
+ *name = (struct qstr) QSTR_INIT(n, s - n);
+ err = 0;
+ }
+ kfree(fh);
+
+ return err;
+
+}
+
+static struct dentry *ovl_lookup_index(struct dentry *dentry,
+ struct dentry *upper,
+ struct dentry *origin)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ struct dentry *index;
+ struct inode *inode;
+ struct qstr name;
+ int err;
+
+ err = ovl_get_index_name(origin, &name);
+ if (err)
+ return ERR_PTR(err);
+
+ index = lookup_one_len_unlocked(name.name, ofs->indexdir, name.len);
+ if (IS_ERR(index)) {
+ pr_warn_ratelimited("overlayfs: failed inode index lookup (ino=%lu, key=%*s, err=%i);\n"
+ "overlayfs: mount with '-o index=off' to disable inodes index.\n",
+ d_inode(origin)->i_ino, name.len, name.name,
+ err);
+ goto out;
+ }
+
+ if (d_is_negative(index)) {
+ if (upper && d_inode(origin)->i_nlink > 1) {
+ pr_warn_ratelimited("overlayfs: hard link with origin but no index (ino=%lu).\n",
+ d_inode(origin)->i_ino);
+ goto fail;
+ }
+
+ dput(index);
+ index = NULL;
+ } else if (upper && d_inode(index) != d_inode(upper)) {
+ inode = d_inode(index);
+ pr_warn_ratelimited("overlayfs: wrong index found (index ino: %lu, upper ino: %lu).\n",
+ d_inode(index)->i_ino,
+ d_inode(upper)->i_ino);
+ goto fail;
+ }
+
+out:
+ kfree(name.name);
+ return index;
+
+fail:
+ dput(index);
+ index = ERR_PTR(-EIO);
+ goto out;
+}
+
/*
* Returns next layer in stack starting from top.
* Returns -1 if this is the last layer.
@@ -409,6 +497,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
struct ovl_entry *roe = dentry->d_sb->s_root->d_fsdata;
struct path *stack = NULL;
struct dentry *upperdir, *upperdentry = NULL;
+ struct dentry *index = NULL;
unsigned int ctr = 0;
struct inode *inode = NULL;
bool upperopaque = false;
@@ -506,6 +595,18 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
}
}
+ /* Lookup index by lower inode and verify it matches upper inode */
+ if (ctr && !d.is_dir && ovl_indexdir(dentry->d_sb)) {
+ struct dentry *origin = stack[0].dentry;
+
+ index = ovl_lookup_index(dentry, upperdentry, origin);
+ if (IS_ERR(index)) {
+ err = PTR_ERR(index);
+ index = NULL;
+ goto out_put;
+ }
+ }
+
oe = ovl_alloc_entry(ctr);
err = -ENOMEM;
if (!oe)
@@ -515,6 +616,9 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr);
dentry->d_fsdata = oe;
+ if (index && !upperdentry)
+ upperdentry = dget(index);
+
if (upperdentry || ctr) {
err = -ENOMEM;
inode = ovl_get_inode(dentry, upperdentry);
@@ -522,9 +626,12 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
goto out_free_oe;
OVL_I(inode)->redirect = upperredirect;
+ if (index)
+ ovl_set_flag(OVL_INDEX, inode);
}
revert_creds(old_cred);
+ dput(index);
kfree(stack);
kfree(d.redirect);
d_add(dentry, inode);
@@ -535,6 +642,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
dentry->d_fsdata = NULL;
kfree(oe);
out_put:
+ dput(index);
for (i = 0; i < ctr; i++)
dput(stack[i].dentry);
kfree(stack);
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 58bbd135a7b3a64b3eb998f33973431da159a93a..437a0301e1b6d9c829e9828023bc17adfcfcf7fe 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -28,6 +28,7 @@ enum ovl_path_type {
enum ovl_flag {
OVL_IMPURE,
+ OVL_INDEX,
};
/*
@@ -236,6 +237,7 @@ static inline bool ovl_is_impuredir(struct dentry *dentry)
/* namei.c */
int ovl_verify_origin(struct dentry *dentry, struct vfsmount *mnt,
struct dentry *origin, bool is_upper, bool set);
+int ovl_get_index_name(struct dentry *origin, struct qstr *name);
int ovl_path_next(int idx, struct dentry *dentry, struct path *path);
struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags);
bool ovl_lower_positive(struct dentry *dentry);