ovl: use ovl_copy_{real,upper}attr() wrappers

When copying inode attributes from the upper or lower layer to ovl inodes
we need to take the upper or lower layer's mount's idmapping into
account. In a lot of places we call ovl_copyattr() only on upper inodes and
in some we call it on either upper or lower inodes. Split this into two
separate helpers.

The first one should only be called on upper
inodes and is thus called ovl_copy_upperattr(). The second one can be
called on upper or lower inodes. We add ovl_copy_realattr() for this
task. The new helper makes use of the previously added ovl_i_path_real()
helper. This is needed to support idmapped base layers with overlay.

When overlay copies the inode information from an upper or lower layer
to the relevant overlay inode it will apply the idmapping of the upper
or lower layer when doing so. The ovl inode ownership will thus always
correctly reflect the ownership of the idmapped upper or lower layer.

All idmapping helpers are nops when no idmapped base layers are used.

Cc: <linux-unionfs@vger.kernel.org>
Tested-by: Giuseppe Scrivano <gscrivan@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 3d58fa721fccb362452bc8a4263d0223463d3e2c..6b03457f72bb10b3ca0cb4532e6e12eb4ff7cb64 100644 (file)
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -884,7 +884,6 @@ static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 {
        int err;
        const struct cred *old_cred;
-       struct dentry *upperdentry;
        bool lower_positive = ovl_lower_positive(dentry);
        LIST_HEAD(list);
 
@@ -927,9 +926,8 @@ static int ovl_do_remove(struct dentry *dentry, bool is_dir)
         * Note: we fail to update ctime if there was no copy-up, only a
         * whiteout
         */
-       upperdentry = ovl_dentry_upper(dentry);
-       if (upperdentry)
-               ovl_copyattr(d_inode(upperdentry), d_inode(dentry));
+       if (ovl_dentry_upper(dentry))
+               ovl_copyattr(d_inode(dentry));
 
 out_drop_write:
        ovl_drop_write(dentry);
@@ -1277,9 +1275,9 @@ static int ovl_rename(struct user_namespace *mnt_userns, struct inode *olddir,
                         (d_inode(new) && ovl_type_origin(new)));
 
        /* copy ctime: */
-       ovl_copyattr(d_inode(olddentry), d_inode(old));
+       ovl_copyattr(d_inode(old));
        if (d_inode(new) && ovl_dentry_upper(new))
-               ovl_copyattr(d_inode(newdentry), d_inode(new));
+               ovl_copyattr(d_inode(new));
 
 out_dput:
        dput(newdentry);

diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 9250e04e97af86495109711013983e5790d03b92..1d9bcc56737346390124193766da273c9a071874 100644 (file)
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -277,7 +277,7 @@ static void ovl_aio_cleanup_handler(struct ovl_aio_req *aio_req)
                __sb_writers_acquired(file_inode(iocb->ki_filp)->i_sb,
                                      SB_FREEZE_WRITE);
                file_end_write(iocb->ki_filp);
-               ovl_copyattr(ovl_inode_real(inode), inode);
+               ovl_copyattr(inode);
        }
 
        orig_iocb->ki_pos = iocb->ki_pos;
@@ -360,7 +360,7 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
 
        inode_lock(inode);
        /* Update mode */
-       ovl_copyattr(ovl_inode_real(inode), inode);
+       ovl_copyattr(inode);
        ret = file_remove_privs(file);
        if (ret)
                goto out_unlock;
@@ -385,7 +385,7 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
                                     ovl_iocb_to_rwf(ifl));
                file_end_write(real.file);
                /* Update size */
-               ovl_copyattr(ovl_inode_real(inode), inode);
+               ovl_copyattr(inode);
        } else {
                struct ovl_aio_req *aio_req;
 
@@ -435,12 +435,11 @@ static ssize_t ovl_splice_write(struct pipe_inode_info *pipe, struct file *out,
        struct fd real;
        const struct cred *old_cred;
        struct inode *inode = file_inode(out);
-       struct inode *realinode = ovl_inode_real(inode);
        ssize_t ret;
 
        inode_lock(inode);
        /* Update mode */
-       ovl_copyattr(realinode, inode);
+       ovl_copyattr(inode);
        ret = file_remove_privs(out);
        if (ret)
                goto out_unlock;
@@ -456,7 +455,7 @@ static ssize_t ovl_splice_write(struct pipe_inode_info *pipe, struct file *out,
 
        file_end_write(real.file);
        /* Update size */
-       ovl_copyattr(realinode, inode);
+       ovl_copyattr(inode);
        revert_creds(old_cred);
        fdput(real);
 
@@ -530,7 +529,7 @@ static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len
        revert_creds(old_cred);
 
        /* Update size */
-       ovl_copyattr(ovl_inode_real(inode), inode);
+       ovl_copyattr(inode);
 
        fdput(real);
 
@@ -602,7 +601,7 @@ static loff_t ovl_copyfile(struct file *file_in, loff_t pos_in,
        revert_creds(old_cred);
 
        /* Update size */
-       ovl_copyattr(ovl_inode_real(inode_out), inode_out);
+       ovl_copyattr(inode_out);
 
        fdput(real_in);
        fdput(real_out);

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index f29e137e6d6073ea1985a0851f281a1e909c777a..bfe7ee0aa51f7738bf9f43f5ee44f517493a0372 100644 (file)
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -81,7 +81,7 @@ int ovl_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
                err = ovl_do_notify_change(ofs, upperdentry, attr);
                revert_creds(old_cred);
                if (!err)
-                       ovl_copyattr(upperdentry->d_inode, dentry->d_inode);
+                       ovl_copyattr(dentry->d_inode);
                inode_unlock(upperdentry->d_inode);
 
                if (winode)
@@ -379,7 +379,7 @@ int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
        revert_creds(old_cred);
 
        /* copy c/mtime */
-       ovl_copyattr(d_inode(realdentry), inode);
+       ovl_copyattr(inode);
 
 out_drop_write:
        ovl_drop_write(dentry);
@@ -581,7 +581,7 @@ int ovl_fileattr_set(struct user_namespace *mnt_userns,
                inode_set_flags(inode, flags, OVL_COPY_I_FLAGS_MASK);
 
                /* Update ctime */
-               ovl_copyattr(ovl_inode_real(inode), inode);
+               ovl_copyattr(inode);
        }
        ovl_drop_write(dentry);
 out:
@@ -791,7 +791,7 @@ void ovl_inode_init(struct inode *inode, struct ovl_inode_params *oip,
                oi->lowerdata = igrab(d_inode(oip->lowerdata));
 
        realinode = ovl_inode_real(inode);
-       ovl_copyattr(realinode, inode);
+       ovl_copyattr(inode);
        ovl_copyflags(realinode, inode);
        ovl_map_ino(inode, ino, fsid);
 }

diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 7b4db563260088b2b3c25c9ba74a7510053d56a7..4f34b7e02eeeb5659345c7929afa147646a4f594 100644 (file)
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -621,16 +621,7 @@ bool ovl_lookup_trap_inode(struct super_block *sb, struct dentry *dir);
 struct inode *ovl_get_trap_inode(struct super_block *sb, struct dentry *dir);
 struct inode *ovl_get_inode(struct super_block *sb,
                            struct ovl_inode_params *oip);
-static inline void ovl_copyattr(struct inode *from, struct inode *to)
-{
-       to->i_uid = from->i_uid;
-       to->i_gid = from->i_gid;
-       to->i_mode = from->i_mode;
-       to->i_atime = from->i_atime;
-       to->i_mtime = from->i_mtime;
-       to->i_ctime = from->i_ctime;
-       i_size_write(to, i_size_read(from));
-}
+void ovl_copyattr(struct inode *to);
 
 /* vfs inode flags copied from real to ovl inode */
 #define OVL_COPY_I_FLAGS_MASK  (S_SYNC | S_NOATIME | S_APPEND | S_IMMUTABLE)

diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 5fdaa9408c84877271030f9a73f426ab1489496a..10032f7c5aa35552f792f47e242eed28cf0a2d5f 100644 (file)
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -470,7 +470,7 @@ static void ovl_dir_version_inc(struct dentry *dentry, bool impurity)
 void ovl_dir_modified(struct dentry *dentry, bool impurity)
 {
        /* Copy mtime/ctime */
-       ovl_copyattr(d_inode(ovl_dentry_upper(dentry)), d_inode(dentry));
+       ovl_copyattr(d_inode(dentry));
 
        ovl_dir_version_inc(dentry, impurity);
 }
@@ -1086,3 +1086,33 @@ int ovl_sync_status(struct ovl_fs *ofs)
 
        return errseq_check(&mnt->mnt_sb->s_wb_err, ofs->errseq);
 }
+
+/*
+ * ovl_copyattr() - copy inode attributes from layer to ovl inode
+ *
+ * When overlay copies inode information from an upper or lower layer to the
+ * relevant overlay inode it will apply the idmapping of the upper or lower
+ * layer when doing so ensuring that the ovl inode ownership will correctly
+ * reflect the ownership of the idmapped upper or lower layer. For example, an
+ * idmapped upper or lower layer mapping id 1001 to id 1000 will take care to
+ * map any lower or upper inode owned by id 1001 to id 1000. These mapping
+ * helpers are nops when the relevant layer isn't idmapped.
+ */
+void ovl_copyattr(struct inode *inode)
+{
+       struct path realpath;
+       struct inode *realinode;
+       struct user_namespace *real_mnt_userns;
+
+       ovl_i_path_real(inode, &realpath);
+       realinode = d_inode(realpath.dentry);
+       real_mnt_userns = mnt_user_ns(realpath.mnt);
+
+       inode->i_uid = i_uid_into_mnt(real_mnt_userns, realinode);
+       inode->i_gid = i_gid_into_mnt(real_mnt_userns, realinode);
+       inode->i_mode = realinode->i_mode;
+       inode->i_atime = realinode->i_atime;
+       inode->i_mtime = realinode->i_mtime;
+       inode->i_ctime = realinode->i_ctime;
+       i_size_write(inode, i_size_read(realinode));
+}