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

[ Upstream commit 2878dffc7db0b5a51e308ccb6b571296b57c82e7 ]

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>
Stable-dep-of: b306e90ffabd ("ovl: remove privs in ovl_copyfile()")
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index f18490813170af41375c24360ba6e136a841b30a..3fc86c51e260c15fff2a31f7266bbdff60724f4e 100644 (file)
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -880,7 +880,6 @@ 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);
 
@@ -923,9 +922,8 @@ 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);
@@ -1272,9 +1270,9 @@ 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 44fea16751f1db104869f8191621cac35bacfcd7..535da9eb4d8bd0ad709fd2f2425ce53e08caabd8 100644 (file)
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -273,7 +273,7 @@ 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;
@@ -356,7 +356,7 @@ 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;
@@ -381,7 +381,7 @@ 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;
 
@@ -431,12 +431,11 @@ 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;
@@ -452,7 +451,7 @@ 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);
 
@@ -526,7 +525,7 @@ 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);
 
@@ -598,7 +597,7 @@ 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 06479bc88b7ed5370de9f446cb0eef33917f44dd..d41f0c8e0e2a5fa283d7382f7f59f10698c8a158 100644 (file)
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -80,7 +80,7 @@ int ovl_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
                err = notify_change(&init_user_ns, upperdentry, attr, NULL);
                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)
@@ -377,7 +377,7 @@ 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);
@@ -579,7 +579,7 @@ 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:
@@ -789,7 +789,7 @@ 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 27f22196266539a868a5bf25bda1d07699ca1a31..2df3e74cdf0f7eaacf8ae58de0fa93beab1df95d 100644 (file)
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -522,16 +522,7 @@ 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 2567918dc6842b9fcd724610768df30431400bd4..9d33ce385bef0b7add3ceb7e9554496cbf1ce899 100644 (file)
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -456,7 +456,7 @@ 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);
 }
@@ -1073,3 +1073,33 @@ 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));
+}