| Message ID | 20240412140122.2607743-2-stefanb@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ima: Fix detection of read/write violations on stacked filesystems | expand |
On Fri, Apr 12, 2024 at 5:01 PM Stefan Berger <stefanb@linux.ibm.com> wrote: > > Define D_REAL_FILEDATA which is to be used as a parameter for d_real() > to return the dentry that is holding the file data, which is either the D_REAL_DATA already does that > upper or the lower denry. The caller is expected to call d_real() again > on the returned dentry to get to lower layers of a stacked filesystem, > if available. > > Signed-off-by: Stefan Berger <stefanb@linux.ibm.com> > --- > fs/overlayfs/super.c | 6 ++++++ > include/linux/dcache.h | 1 + > 2 files changed, 7 insertions(+) > > diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c > index 06a231970cb5..f466ad89b005 100644 > --- a/fs/overlayfs/super.c > +++ b/fs/overlayfs/super.c > @@ -36,6 +36,7 @@ static struct dentry *ovl_d_real(struct dentry *dentry, enum d_real_type type) > switch (type) { > case D_REAL_DATA: > case D_REAL_METADATA: > + case D_REAL_FILEDATA: > break; > default: > goto bug; > @@ -47,6 +48,11 @@ static struct dentry *ovl_d_real(struct dentry *dentry, enum d_real_type type) > } > > upper = ovl_dentry_upper(dentry); > + if (type == D_REAL_FILEDATA) { > + if (ovl_has_upperdata(d_inode(dentry))) > + return upper; This one is already the returned value for D_REAL_DATA > + return ovl_dentry_lower(dentry); And this one is a wrong value, because the lower file's data is at ovl_dentry_lowerdata(), which is what D_REAL_DATA returns. So it is not clear to me what it is that you tried to do here. Thanks, Amir.
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 06a231970cb5..f466ad89b005 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -36,6 +36,7 @@ static struct dentry *ovl_d_real(struct dentry *dentry, enum d_real_type type) switch (type) { case D_REAL_DATA: case D_REAL_METADATA: + case D_REAL_FILEDATA: break; default: goto bug; @@ -47,6 +48,11 @@ static struct dentry *ovl_d_real(struct dentry *dentry, enum d_real_type type) } upper = ovl_dentry_upper(dentry); + if (type == D_REAL_FILEDATA) { + if (ovl_has_upperdata(d_inode(dentry))) + return upper; + return ovl_dentry_lower(dentry); + } if (upper && (type == D_REAL_METADATA || ovl_has_upperdata(d_inode(dentry)))) return upper; diff --git a/include/linux/dcache.h b/include/linux/dcache.h index bf53e3894aae..e4e54fb2cf4e 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -128,6 +128,7 @@ enum dentry_d_lock_class enum d_real_type { D_REAL_DATA, D_REAL_METADATA, + D_REAL_FILEDATA, }; struct dentry_operations {
Define D_REAL_FILEDATA which is to be used as a parameter for d_real() to return the dentry that is holding the file data, which is either the upper or the lower denry. The caller is expected to call d_real() again on the returned dentry to get to lower layers of a stacked filesystem, if available. Signed-off-by: Stefan Berger <stefanb@linux.ibm.com> --- fs/overlayfs/super.c | 6 ++++++ include/linux/dcache.h | 1 + 2 files changed, 7 insertions(+)