When lower fs is a nested overlayfs, calling encode_fh() on a lower
directory dentry may trigger copy up and take sb_writers on the upper fs
of the lower nested overlayfs.
The lower nested overlayfs may have the same upper fs as this overlayfs,
so nested sb_writers lock is illegal.
Move all the callers that encode lower fh to before ovl_want_write().
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/copy_up.c | 52 ++++++++++++++++++++++++----------------
fs/overlayfs/namei.c | 37 +++++++++++++++++++++-------
fs/overlayfs/overlayfs.h | 26 ++++++++++++++------
fs/overlayfs/super.c | 20 +++++++++++-----
fs/overlayfs/util.c | 11 ++++++++-
5 files changed, 103 insertions(+), 43 deletions(-)
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index add5861cf06b..c0bac6bd90cf 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -434,29 +434,29 @@ struct ovl_fh *ovl_encode_real_fh(struct ovl_fs *ofs, struct dentry *real,
return ERR_PTR(err);
}
-int ovl_set_origin(struct ovl_fs *ofs, struct dentry *lower,
- struct dentry *upper)
+struct ovl_fh *ovl_get_origin_fh(struct ovl_fs *ofs, struct dentry *origin)
{
- const struct ovl_fh *fh = NULL;
- int err;
-
/*
* When lower layer doesn't support export operations store a 'null' fh,
* so we can use the overlay.origin xattr to distignuish between a copy
* up and a pure upper inode.
*/
- if (ovl_can_decode_fh(lower->d_sb)) {
- fh = ovl_encode_real_fh(ofs, lower, false);
- if (IS_ERR(fh))
- return PTR_ERR(fh);
- }
+ if (!ovl_can_decode_fh(origin->d_sb))
+ return NULL;
+
+ return ovl_encode_real_fh(ofs, origin, false);
+}
+
+int ovl_set_origin_fh(struct ovl_fs *ofs, const struct ovl_fh *fh,
+ struct dentry *upper)
+{
+ int err;
/*
* Do not fail when upper doesn't support xattrs.
*/
err = ovl_check_setxattr(ofs, upper, OVL_XATTR_ORIGIN, fh->buf,
fh ? fh->fb.len : 0, 0);
- kfree(fh);
/* Ignore -EPERM from setting "user.*" on symlink/special */
return err == -EPERM ? 0 : err;
@@ -484,7 +484,7 @@ static int ovl_set_upper_fh(struct ovl_fs *ofs, struct dentry *upper,
*
* Caller must hold i_mutex on indexdir.
*/
-static int ovl_create_index(struct dentry *dentry, struct dentry *origin,
+static int ovl_create_index(struct dentry *dentry, const struct ovl_fh *fh,
struct dentry *upper)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
@@ -510,7 +510,7 @@ static int ovl_create_index(struct dentry *dentry, struct dentry *origin,
if (WARN_ON(ovl_test_flag(OVL_INDEX, d_inode(dentry))))
return -EIO;
- err = ovl_get_index_name(ofs, origin, &name);
+ err = ovl_get_index_name_fh(fh, &name);
if (err)
return err;
@@ -549,6 +549,7 @@ struct ovl_copy_up_ctx {
struct dentry *destdir;
struct qstr destname;
struct dentry *workdir;
+ const struct ovl_fh *origin_fh;
bool origin;
bool indexed;
bool metacopy;
@@ -648,7 +649,7 @@ static int ovl_copy_up_metadata(struct ovl_copy_up_ctx *c, struct dentry *temp)
* hard link.
*/
if (c->origin) {
- err = ovl_set_origin(ofs, c->lowerpath.dentry, temp);
+ err = ovl_set_origin_fh(ofs, c->origin_fh, temp);
if (err)
return err;
}
@@ -771,7 +772,7 @@ static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
goto cleanup;
if (S_ISDIR(c->stat.mode) && c->indexed) {
- err = ovl_create_index(c->dentry, c->lowerpath.dentry, temp);
+ err = ovl_create_index(c->dentry, c->origin_fh, temp);
if (err)
goto cleanup;
}
@@ -889,6 +890,8 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
{
int err;
struct ovl_fs *ofs = OVL_FS(c->dentry->d_sb);
+ struct dentry *origin = c->lowerpath.dentry;
+ struct ovl_fh *fh = NULL;
bool to_index = false;
/*
@@ -905,17 +908,25 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
to_index = true;
}
- if (S_ISDIR(c->stat.mode) || c->stat.nlink == 1 || to_index)
+ if (S_ISDIR(c->stat.mode) || c->stat.nlink == 1 || to_index) {
+ fh = ovl_get_origin_fh(ofs, origin);
+ if (IS_ERR(fh))
+ return PTR_ERR(fh);
+
+ /* origin_fh may be NULL */
+ c->origin_fh = fh;
c->origin = true;
+ }
if (to_index) {
c->destdir = ovl_indexdir(c->dentry->d_sb);
- err = ovl_get_index_name(ofs, c->lowerpath.dentry, &c->destname);
+ err = ovl_get_index_name(ofs, origin, &c->destname);
if (err)
- return err;
+ goto out;
} else if (WARN_ON(!c->parent)) {
/* Disconnected dentry must be copied up to index dir */
- return -EIO;
+ err = -EIO;
+ goto out;
} else {
/*
* Mark parent "impure" because it may now contain non-pure
@@ -925,7 +936,7 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
err = ovl_set_impure(c->parent, c->destdir);
ovl_end_write(c->dentry);
if (err)
- return err;
+ goto out;
}
/* Should we copyup with O_TMPFILE or with workdir? */
@@ -959,6 +970,7 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
out:
if (to_index)
kfree(c->destname.name);
+ kfree(fh);
return err;
}
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index 80391c687c2a..f10ac4ae35f0 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -507,6 +507,19 @@ static int ovl_verify_fh(struct ovl_fs *ofs, struct dentry *dentry,
return err;
}
+int ovl_verify_set_fh(struct ovl_fs *ofs, struct dentry *dentry,
+ enum ovl_xattr ox, const struct ovl_fh *fh,
+ bool is_upper, bool set)
+{
+ int err;
+
+ err = ovl_verify_fh(ofs, dentry, ox, fh);
+ if (set && err == -ENODATA)
+ err = ovl_setxattr(ofs, dentry, ox, fh->buf, fh->fb.len);
+
+ return err;
+}
+
/*
* Verify that @real dentry matches the file handle stored in xattr @name.
*
@@ -515,9 +528,9 @@ static int ovl_verify_fh(struct ovl_fs *ofs, struct dentry *dentry,
*
* Return 0 on match, -ESTALE on mismatch, -ENODATA on no xattr, < 0 on error.
*/
-int ovl_verify_set_fh(struct ovl_fs *ofs, struct dentry *dentry,
- enum ovl_xattr ox, struct dentry *real, bool is_upper,
- bool set)
+int ovl_verify_origin_xattr(struct ovl_fs *ofs, struct dentry *dentry,
+ enum ovl_xattr ox, struct dentry *real,
+ bool is_upper, bool set)
{
struct inode *inode;
struct ovl_fh *fh;
@@ -530,9 +543,7 @@ int ovl_verify_set_fh(struct ovl_fs *ofs, struct dentry *dentry,
goto fail;
}
- err = ovl_verify_fh(ofs, dentry, ox, fh);
- if (set && err == -ENODATA)
- err = ovl_setxattr(ofs, dentry, ox, fh->buf, fh->fb.len);
+ err = ovl_verify_set_fh(ofs, dentry, ox, fh, is_upper, set);
if (err)
goto fail;
@@ -548,6 +559,7 @@ int ovl_verify_set_fh(struct ovl_fs *ofs, struct dentry *dentry,
goto out;
}
+
/* Get upper dentry from index */
struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index,
bool connected)
@@ -684,7 +696,7 @@ int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index)
goto out;
}
-static int ovl_get_index_name_fh(struct ovl_fh *fh, struct qstr *name)
+int ovl_get_index_name_fh(const struct ovl_fh *fh, struct qstr *name)
{
char *n, *s;
@@ -873,20 +885,27 @@ int ovl_path_next(int idx, struct dentry *dentry, struct path *path)
static int ovl_fix_origin(struct ovl_fs *ofs, struct dentry *dentry,
struct dentry *lower, struct dentry *upper)
{
+ const struct ovl_fh *fh;
int err;
if (ovl_check_origin_xattr(ofs, upper))
return 0;
+ fh = ovl_get_origin_fh(ofs, lower);
+ if (IS_ERR(fh))
+ return PTR_ERR(fh);
+
err = ovl_want_write(dentry);
if (err)
- return err;
+ goto out;
- err = ovl_set_origin(ofs, lower, upper);
+ err = ovl_set_origin_fh(ofs, fh, upper);
if (!err)
err = ovl_set_impure(dentry->d_parent, upper->d_parent);
ovl_drop_write(dentry);
+out:
+ kfree(fh);
return err;
}
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 6da49bf78b90..4e8a2b830c71 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -628,11 +628,15 @@ struct dentry *ovl_decode_real_fh(struct ovl_fs *ofs, struct ovl_fh *fh,
int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
struct dentry *upperdentry, struct ovl_path **stackp);
int ovl_verify_set_fh(struct ovl_fs *ofs, struct dentry *dentry,
- enum ovl_xattr ox, struct dentry *real, bool is_upper,
- bool set);
+ enum ovl_xattr ox, const struct ovl_fh *fh,
+ bool is_upper, bool set);
+int ovl_verify_origin_xattr(struct ovl_fs *ofs, struct dentry *dentry,
+ enum ovl_xattr ox, struct dentry *real,
+ bool is_upper, bool set);
struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index,
bool connected);
int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index);
+int ovl_get_index_name_fh(const struct ovl_fh *fh, struct qstr *name);
int ovl_get_index_name(struct ovl_fs *ofs, struct dentry *origin,
struct qstr *name);
struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh);
@@ -644,17 +648,24 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
unsigned int flags);
bool ovl_lower_positive(struct dentry *dentry);
+static inline int ovl_verify_origin_fh(struct ovl_fs *ofs, struct dentry *upper,
+ const struct ovl_fh *fh, bool set)
+{
+ return ovl_verify_set_fh(ofs, upper, OVL_XATTR_ORIGIN, fh, false, set);
+}
+
static inline int ovl_verify_origin(struct ovl_fs *ofs, struct dentry *upper,
struct dentry *origin, bool set)
{
- return ovl_verify_set_fh(ofs, upper, OVL_XATTR_ORIGIN, origin,
- false, set);
+ return ovl_verify_origin_xattr(ofs, upper, OVL_XATTR_ORIGIN, origin,
+ false, set);
}
static inline int ovl_verify_upper(struct ovl_fs *ofs, struct dentry *index,
struct dentry *upper, bool set)
{
- return ovl_verify_set_fh(ofs, index, OVL_XATTR_UPPER, upper, true, set);
+ return ovl_verify_origin_xattr(ofs, index, OVL_XATTR_UPPER, upper,
+ true, set);
}
/* readdir.c */
@@ -819,8 +830,9 @@ int ovl_copy_xattr(struct super_block *sb, const struct path *path, struct dentr
int ovl_set_attr(struct ovl_fs *ofs, struct dentry *upper, struct kstat *stat);
struct ovl_fh *ovl_encode_real_fh(struct ovl_fs *ofs, struct dentry *real,
bool is_upper);
-int ovl_set_origin(struct ovl_fs *ofs, struct dentry *lower,
- struct dentry *upper);
+struct ovl_fh *ovl_get_origin_fh(struct ovl_fs *ofs, struct dentry *origin);
+int ovl_set_origin_fh(struct ovl_fs *ofs, const struct ovl_fh *fh,
+ struct dentry *upper);
/* export.c */
extern const struct export_operations ovl_export_operations;
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index def266b5e2a3..93d500d4fda9 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -881,15 +881,20 @@ static int ovl_get_indexdir(struct super_block *sb, struct ovl_fs *ofs,
{
struct vfsmount *mnt = ovl_upper_mnt(ofs);
struct dentry *indexdir;
+ struct dentry *origin = ovl_lowerstack(oe)->dentry;
+ const struct ovl_fh *fh;
int err;
+ fh = ovl_get_origin_fh(ofs, origin);
+ if (IS_ERR(fh))
+ return PTR_ERR(fh);
+
err = mnt_want_write(mnt);
if (err)
- return err;
+ goto out_free_fh;
/* Verify lower root is upper root origin */
- err = ovl_verify_origin(ofs, upperpath->dentry,
- ovl_lowerstack(oe)->dentry, true);
+ err = ovl_verify_origin_fh(ofs, upperpath->dentry, fh, true);
if (err) {
pr_err("failed to verify upper root origin\n");
goto out;
@@ -921,9 +926,10 @@ static int ovl_get_indexdir(struct super_block *sb, struct ovl_fs *ofs,
* directory entries.
*/
if (ovl_check_origin_xattr(ofs, ofs->indexdir)) {
- err = ovl_verify_set_fh(ofs, ofs->indexdir,
- OVL_XATTR_ORIGIN,
- upperpath->dentry, true, false);
+ err = ovl_verify_origin_xattr(ofs, ofs->indexdir,
+ OVL_XATTR_ORIGIN,
+ upperpath->dentry, true,
+ false);
if (err)
pr_err("failed to verify index dir 'origin' xattr\n");
}
@@ -941,6 +947,8 @@ static int ovl_get_indexdir(struct super_block *sb, struct ovl_fs *ofs,
out:
mnt_drop_write(mnt);
+out_free_fh:
+ kfree(fh);
return err;
}
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 4e67ef0cc8da..5d92252cee30 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -1013,12 +1013,18 @@ static void ovl_cleanup_index(struct dentry *dentry)
struct dentry *index = NULL;
struct inode *inode;
struct qstr name = { };
+ bool got_write = false;
int err;
err = ovl_get_index_name(ofs, lowerdentry, &name);
if (err)
goto fail;
+ err = ovl_want_write(dentry);
+ if (err)
+ goto fail;
+
+ got_write = true;
inode = d_inode(upperdentry);
if (!S_ISDIR(inode->i_mode) && inode->i_nlink != 1) {
pr_warn_ratelimited("cleanup linked index (%pd2, ino=%lu, nlink=%u)\n",
@@ -1056,6 +1062,8 @@ static void ovl_cleanup_index(struct dentry *dentry)
goto fail;
out:
+ if (got_write)
+ ovl_drop_write(dentry);
kfree(name.name);
dput(index);
return;
@@ -1135,6 +1143,8 @@ void ovl_nlink_end(struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
+ ovl_drop_write(dentry);
+
if (ovl_test_flag(OVL_INDEX, inode) && inode->i_nlink == 0) {
const struct cred *old_cred;
@@ -1143,7 +1153,6 @@ void ovl_nlink_end(struct dentry *dentry)
revert_creds(old_cred);
}
- ovl_drop_write(dentry);
ovl_inode_unlock(inode);
}
--
2.34.1
