From: Miklos Szeredi <mszeredi@xxxxxxx>
[ Upstream commit cc6f67bcafcb6bbbb2d1be1603dcd95125a52800 ]
OpenWRT folks reported that overlayfs fails to mount if upper fs is full,
because workdir can't be created. Wordir creation can fail for various
other reasons too.
There's no reason that the mount itself should fail, overlayfs can work
fine without a workdir, as long as the overlay isn't modified.
So mount it read-only and don't allow remounting read-write.
Add a couple of WARN_ON()s for the impossible case of workdir being used
despite being read-only.
Reported-by: Bastian Bittorf <bittorf@xxxxxxxxxxxxxx>
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v3.18+
Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
fs/overlayfs/copy_up.c | 3 +++
fs/overlayfs/dir.c | 9 +++++++++
fs/overlayfs/super.c | 22 ++++++++++++++++++++++
3 files changed, 34 insertions(+)
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index ea10a87..b7d6dc3 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -300,6 +300,9 @@ int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
struct cred *override_cred;
char *link = NULL;
+ if (WARN_ON(!workdir))
+ return -EROFS;
+
ovl_path_upper(parent, &parentpath);
upperdir = parentpath.dentry;
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 8ffc4b9..00d6583 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -222,6 +222,9 @@ static struct dentry *ovl_clear_empty(struct dentry *dentry,
struct kstat stat;
int err;
+ if (WARN_ON(!workdir))
+ return ERR_PTR(-EROFS);
+
err = ovl_lock_rename_workdir(workdir, upperdir);
if (err)
goto out;
@@ -322,6 +325,9 @@ static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
struct dentry *newdentry;
int err;
+ if (WARN_ON(!workdir))
+ return -EROFS;
+
err = ovl_lock_rename_workdir(workdir, upperdir);
if (err)
goto out;
@@ -506,6 +512,9 @@ static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
struct dentry *opaquedir = NULL;
int err;
+ if (WARN_ON(!workdir))
+ return -EROFS;
+
if (is_dir) {
opaquedir = ovl_check_empty_and_clear(dentry);
err = PTR_ERR(opaquedir);
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index f16d318..e2c21a5 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -723,11 +723,30 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
goto out_put_workpath;
}
+<<<<<<< HEAD
ufs->upper_mnt = clone_private_mount(&upperpath);
err = PTR_ERR(ufs->upper_mnt);
if (IS_ERR(ufs->upper_mnt)) {
pr_err("overlayfs: failed to clone upperpath\n");
goto out_put_workpath;
+=======
+ if (ufs->config.upperdir) {
+ ufs->upper_mnt = clone_private_mount(&upperpath);
+ err = PTR_ERR(ufs->upper_mnt);
+ if (IS_ERR(ufs->upper_mnt)) {
+ pr_err("overlayfs: failed to clone upperpath\n");
+ goto out_put_lowerpath;
+ }
+
+ ufs->workdir = ovl_workdir_create(ufs->upper_mnt, workpath.dentry);
+ err = PTR_ERR(ufs->workdir);
+ if (IS_ERR(ufs->workdir)) {
+ pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n",
+ ufs->config.workdir, OVL_WORKDIR_NAME, -err);
+ sb->s_flags |= MS_RDONLY;
+ ufs->workdir = NULL;
+ }
+>>>>>>> 2577f42... ovl: mount read-only if workdir can't be created
}
ufs->lower_mnt = clone_private_mount(&lowerpath);
@@ -784,9 +803,12 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
out_put_workdir:
dput(ufs->workdir);
+<<<<<<< HEAD
out_put_lower_mnt:
mntput(ufs->lower_mnt);
out_put_upper_mnt:
+=======
+>>>>>>> 2577f42... ovl: mount read-only if workdir can't be created
mntput(ufs->upper_mnt);
out_put_workpath:
path_put(&workpath);
--
2.1.0
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