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| author | Amir Goldstein <amir73il@gmail.com> | 2017-06-21 15:28:38 +0300 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2017-07-04 23:03:17 +0300 |
| commit | 54fb347e836faadaed2a5617fb4dd4a4597d0490 (patch) | |
| tree | 776d77e3848edf181ebeeda5bea8169c8937c6bc /fs/overlayfs/copy_up.c | |
| parent | 8b88a2e6403638b56556ed5b1c60d9318eefea9c (diff) | |
| download | linux-54fb347e836faadaed2a5617fb4dd4a4597d0490.tar.xz | |
ovl: verify index dir matches upper dir
An index dir contains persistent hardlinks to files in upper dir.
Therefore, we must never mount an existing index dir with a differnt
upper dir.
Store the upper root dir file handle in index dir inode when index
dir is created and verify the file handle before using an existing
index dir on mount.
Add an 'is_upper' flag to the overlay file handle encoding and set it
when encoding the upper root file handle. This is not critical for index
dir verification, but it is good practice towards a standard overlayfs
file handle format for NFS export.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/overlayfs/copy_up.c')
| -rw-r--r-- | fs/overlayfs/copy_up.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index 42807cb57da0..5e8fd99557e1 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -233,7 +233,7 @@ int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat) return err; } -struct ovl_fh *ovl_encode_fh(struct dentry *lower) +struct ovl_fh *ovl_encode_fh(struct dentry *lower, bool is_upper) { struct ovl_fh *fh; int fh_type, fh_len, dwords; @@ -272,6 +272,14 @@ struct ovl_fh *ovl_encode_fh(struct dentry *lower) fh->magic = OVL_FH_MAGIC; fh->type = fh_type; fh->flags = OVL_FH_FLAG_CPU_ENDIAN; + /* + * When we will want to decode an overlay dentry from this handle + * and all layers are on the same fs, if we get a disconncted real + * dentry when we decode fid, the only way to tell if we should assign + * it to upperdentry or to lowerstack is by checking this flag. + */ + if (is_upper) + fh->flags |= OVL_FH_FLAG_PATH_UPPER; fh->len = fh_len; fh->uuid = *uuid; memcpy(fh->fid, buf, buflen); @@ -293,7 +301,7 @@ static int ovl_set_origin(struct dentry *dentry, struct dentry *lower, * up and a pure upper inode. */ if (ovl_can_decode_fh(lower->d_sb)) { - fh = ovl_encode_fh(lower); + fh = ovl_encode_fh(lower, false); if (IS_ERR(fh)) return PTR_ERR(fh); } |