4.15-stable review patch. If anyone has any objections, please let me know.
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From: Amir Goldstein amir73il@gmail.com
commit 2ba9d57e65044859f7ff133bcb0a902769bf3bc6 upstream.
There are several write operations on upper fs not covered by mnt_want_write():
- test set/remove OPAQUE xattr - test create O_TMPFILE - set ORIGIN xattr in ovl_verify_origin() - cleanup of index entries in ovl_indexdir_cleanup()
Some of these go way back, but this patch only applies over the v4.14 re-factoring of ovl_fill_super().
Signed-off-by: Amir Goldstein amir73il@gmail.com Signed-off-by: Miklos Szeredi mszeredi@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/overlayfs/super.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-)
--- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -520,10 +520,6 @@ static struct dentry *ovl_workdir_create bool retried = false; bool locked = false;
- err = mnt_want_write(mnt); - if (err) - goto out_err; - inode_lock_nested(dir, I_MUTEX_PARENT); locked = true;
@@ -588,7 +584,6 @@ retry: goto out_err; } out_unlock: - mnt_drop_write(mnt); if (locked) inode_unlock(dir);
@@ -930,12 +925,17 @@ out:
static int ovl_make_workdir(struct ovl_fs *ofs, struct path *workpath) { + struct vfsmount *mnt = ofs->upper_mnt; struct dentry *temp; int err;
+ err = mnt_want_write(mnt); + if (err) + return err; + ofs->workdir = ovl_workdir_create(ofs, OVL_WORKDIR_NAME, false); if (!ofs->workdir) - return 0; + goto out;
/* * Upper should support d_type, else whiteouts are visible. Given @@ -945,7 +945,7 @@ static int ovl_make_workdir(struct ovl_f */ err = ovl_check_d_type_supported(workpath); if (err < 0) - return err; + goto out;
/* * We allowed this configuration and don't want to break users over @@ -969,6 +969,7 @@ static int ovl_make_workdir(struct ovl_f if (err) { ofs->noxattr = true; pr_warn("overlayfs: upper fs does not support xattr.\n"); + err = 0; } else { vfs_removexattr(ofs->workdir, OVL_XATTR_OPAQUE); } @@ -980,7 +981,9 @@ static int ovl_make_workdir(struct ovl_f pr_warn("overlayfs: upper fs does not support file handles, falling back to index=off.\n"); }
- return 0; +out: + mnt_drop_write(mnt); + return err; }
static int ovl_get_workdir(struct ovl_fs *ofs, struct path *upperpath) @@ -1027,8 +1030,13 @@ out: static int ovl_get_indexdir(struct ovl_fs *ofs, struct ovl_entry *oe, struct path *upperpath) { + struct vfsmount *mnt = ofs->upper_mnt; int err;
+ err = mnt_want_write(mnt); + if (err) + return err; + /* Verify lower root is upper root origin */ err = ovl_verify_origin(upperpath->dentry, oe->lowerstack[0].dentry, false, true); @@ -1056,6 +1064,7 @@ static int ovl_get_indexdir(struct ovl_f pr_warn("overlayfs: try deleting index dir or mounting with '-o index=off' to disable inodes index.\n");
out: + mnt_drop_write(mnt); return err; }