From 82b749b2c65e9d108c1c5598dc0a5f436b525f42 Mon Sep 17 00:00:00 2001
From: Amir Goldstein <amir73il@gmail.com>
Date: Wed, 17 May 2017 00:12:40 +0300
Subject: [PATCH] ovl: check on mount time if upper fs supports setting xattr
xattr are needed by overlayfs for setting opaque dir, redirect dir
and copy up origin.
Check at mount time by trying to set the overlay.opaque xattr on the
workdir and if that fails issue a warning message.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
fs/overlayfs/overlayfs.h | 3 +++
fs/overlayfs/ovl_entry.h | 1 +
fs/overlayfs/super.c | 13 +++++++++++++
fs/overlayfs/util.c | 21 +++++++++++++++++++++
4 files changed, 38 insertions(+)
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index caa36cb9c46de9..ce7c3aba61e46f 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -279,3 +279,6 @@ int ovl_copy_up(struct dentry *dentry);
int ovl_copy_up_flags(struct dentry *dentry, int flags);
int ovl_copy_xattr(struct dentry *old, struct dentry *new);
int ovl_set_attr(struct dentry *upper, struct kstat *stat);
+int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
+ const char *name, const void *value, size_t size,
+ int xerr);
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index b2023ddb853237..ad86c0a302ebea 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -28,6 +28,7 @@ struct ovl_fs {
/* creds of process who forced instantiation of super block */
const struct cred *creator_cred;
bool tmpfile;
+ bool noxattr;
wait_queue_head_t copyup_wq;
/* sb common to all layers */
struct super_block *same_sb;
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 9828b7de89992e..f1647626a882f5 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -891,6 +891,19 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
dput(temp);
else
pr_warn("overlayfs: upper fs does not support tmpfile.\n");
+
+ /*
+ * Check if upper/work fs supports trusted.overlay.*
+ * xattr
+ */
+ err = ovl_do_setxattr(ufs->workdir, OVL_XATTR_OPAQUE,
+ "0", 1, 0);
+ if (err) {
+ ufs->noxattr = true;
+ pr_warn("overlayfs: upper fs does not support xattr.\n");
+ } else {
+ vfs_removexattr(ufs->workdir, OVL_XATTR_OPAQUE);
+ }
}
}
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index cfdea47313a10e..b5a0dc36ee968c 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -303,3 +303,24 @@ void ovl_copy_up_end(struct dentry *dentry)
wake_up_locked(&ofs->copyup_wq);
spin_unlock(&ofs->copyup_wq.lock);
}
+
+int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
+ const char *name, const void *value, size_t size,
+ int xerr)
+{
+ int err;
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+
+ if (ofs->noxattr)
+ return xerr;
+
+ err = ovl_do_setxattr(upperdentry, name, value, size, 0);
+
+ if (err == -EOPNOTSUPP) {
+ pr_warn("overlayfs: cannot set %s xattr on upper\n", name);
+ ofs->noxattr = true;
+ return xerr;
+ }
+
+ return err;
+}
--
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