For a merge dir that was copied up before v4.12 or that was hand crafted
offline (e.g. mkdir {upper/lower}/dir), upper dir does not contain the
'trusted.overlay.origin' xattr. In that case, stat(2) on the merge dir
returns the lower dir st_ino, but getdents(2) returns the upper dir d_ino.
After this change, on merge dir lookup, missing origin xattr on upper
dir will be fixed and 'impure' xattr will be fixed on parent of the legacy
merge dir.
Suggested-by: zhangyi (F) <yi.zhang@xxxxxxxxxx>
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
Zhangyi,
Please review/test this patch.
I ended up applying it at the bottom of verify_dir [1] series,
so it could be merged to v4.15 and/or easily backported to v4.14
(where consistent d_ino was merged) if Miklos thinks this is an important
use case to fix.
Thanks,
Amir.
[1] https://github.com/amir73il/linux/commits/ovl-verify-dir
fs/overlayfs/namei.c | 36 +++++++++++++++++++++++++++++++-----
fs/overlayfs/overlayfs.h | 2 +-
fs/overlayfs/super.c | 5 +++--
3 files changed, 35 insertions(+), 8 deletions(-)
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index 9cf15463754c..bd7375c05f7d 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -343,13 +343,13 @@ static int ovl_verify_origin_fh(struct dentry *dentry, const struct ovl_fh *fh)
/*
* Verify that an inode matches the origin file handle stored in upper inode.
*
- * If @set is true and there is no stored file handle, encode and store origin
- * file handle in OVL_XATTR_ORIGIN.
+ * If @set is non-null and there is no stored file handle, set *@set to true
+ * and try to encode and store origin file handle in OVL_XATTR_ORIGIN.
*
- * Return 0 on match, -ESTALE on mismatch, < 0 on error.
+ * Return 0 on match or successful set, -ESTALE on mismatch, < 0 on error.
*/
int ovl_verify_origin(struct dentry *dentry, struct dentry *origin,
- bool is_upper, bool set)
+ bool is_upper, bool *set)
{
struct inode *inode;
struct ovl_fh *fh;
@@ -361,8 +361,13 @@ int ovl_verify_origin(struct dentry *dentry, struct dentry *origin,
goto fail;
err = ovl_verify_origin_fh(dentry, fh);
- if (set && err == -ENODATA)
+ if (set && err == -ENODATA) {
+ *set = true;
err = ovl_do_setxattr(dentry, OVL_XATTR_ORIGIN, fh, fh->len, 0);
+ if (err)
+ goto fail;
+ }
+
if (err)
goto fail;
@@ -674,6 +679,27 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
if (!this)
continue;
+ /*
+ * If no origin fh is stored in upper of a merge dir, store fh
+ * of upper most lower dir and set upper parent "impure".
+ */
+ if (upperdentry && !ctr) {
+ bool set = false;
+
+ err = ovl_verify_origin(upperdentry, this, false, &set);
+ if (set && !err) {
+ err = ovl_set_impure(dentry->d_parent,
+ upperdentry->d_parent);
+ }
+ if (set && err)
+ goto out_put;
+
+ /*
+ * Ignore merge dir origin mismatch, which may have
+ * been caused by copying layers
+ */
+ }
+
stack[ctr].dentry = this;
stack[ctr].layer = lower.layer;
ctr++;
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index b489099ccd49..6620db670afa 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -250,7 +250,7 @@ static inline bool ovl_is_impuredir(struct dentry *dentry)
/* namei.c */
int ovl_verify_origin(struct dentry *dentry, struct dentry *origin,
- bool is_upper, bool set);
+ bool is_upper, bool *set);
int ovl_verify_index(struct dentry *index, struct ovl_path *lower,
unsigned int numlower);
int ovl_get_index_name(struct dentry *origin, struct qstr *name);
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 76440feb79f6..f548717e3388 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1026,11 +1026,12 @@ static int ovl_get_workdir(struct ovl_fs *ofs, struct path *upperpath)
static int ovl_get_indexdir(struct ovl_fs *ofs, struct ovl_entry *oe,
struct path *upperpath)
{
+ bool set;
int err;
/* Verify lower root is upper root origin */
err = ovl_verify_origin(upperpath->dentry, oe->lowerstack[0].dentry,
- false, true);
+ false, &set);
if (err) {
pr_err("overlayfs: failed to verify upper root origin\n");
goto out;
@@ -1040,7 +1041,7 @@ static int ovl_get_indexdir(struct ovl_fs *ofs, struct ovl_entry *oe,
if (ofs->indexdir) {
/* Verify upper root is index dir origin */
err = ovl_verify_origin(ofs->indexdir, upperpath->dentry,
- true, true);
+ true, &set);
if (err)
pr_err("overlayfs: failed to verify index dir origin\n");
--
2.7.4
--
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