fs: port ->permission() to pass mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

1 files changed, 48 insertions, 53 deletions

diff --git a/fs/ksmbd/vfs.c b/fs/ksmbd/vfs.c
index 21f420d21b3e..98e07c9f9869 100644
--- a/fs/ksmbd/vfs.c
+++ b/fs/ksmbd/vfs.c
@@ -69,14 +69,14 @@ static void ksmbd_vfs_inherit_owner(struct ksmbd_work *work,
  *
  * the reference count of @parent isn't incremented.
  */
-int ksmbd_vfs_lock_parent(struct user_namespace *user_ns, struct dentry *parent,
+int ksmbd_vfs_lock_parent(struct mnt_idmap *idmap, struct dentry *parent,
 			  struct dentry *child)
 {
 	struct dentry *dentry;
 	int ret = 0;
 
 	inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
-	dentry = lookup_one(user_ns, child->d_name.name, parent,
+	dentry = lookup_one(idmap, child->d_name.name, parent,
 			    child->d_name.len);
 	if (IS_ERR(dentry)) {
 		ret = PTR_ERR(dentry);
@@ -96,20 +96,20 @@ out_err:
 	return ret;
 }
 
-int ksmbd_vfs_may_delete(struct user_namespace *user_ns,
+int ksmbd_vfs_may_delete(struct mnt_idmap *idmap,
 			 struct dentry *dentry)
 {
 	struct dentry *parent;
 	int ret;
 
 	parent = dget_parent(dentry);
-	ret = ksmbd_vfs_lock_parent(user_ns, parent, dentry);
+	ret = ksmbd_vfs_lock_parent(idmap, parent, dentry);
 	if (ret) {
 		dput(parent);
 		return ret;
 	}
 
-	ret = inode_permission(user_ns, d_inode(parent),
+	ret = inode_permission(idmap, d_inode(parent),
 			       MAY_EXEC | MAY_WRITE);
 
 	inode_unlock(d_inode(parent));
@@ -117,7 +117,7 @@ int ksmbd_vfs_may_delete(struct user_namespace *user_ns,
 	return ret;
 }
 
-int ksmbd_vfs_query_maximal_access(struct user_namespace *user_ns,
+int ksmbd_vfs_query_maximal_access(struct mnt_idmap *idmap,
 				   struct dentry *dentry, __le32 *daccess)
 {
 	struct dentry *parent;
@@ -125,26 +125,26 @@ int ksmbd_vfs_query_maximal_access(struct user_namespace *user_ns,
 
 	*daccess = cpu_to_le32(FILE_READ_ATTRIBUTES | READ_CONTROL);
 
-	if (!inode_permission(user_ns, d_inode(dentry), MAY_OPEN | MAY_WRITE))
+	if (!inode_permission(idmap, d_inode(dentry), MAY_OPEN | MAY_WRITE))
 		*daccess |= cpu_to_le32(WRITE_DAC | WRITE_OWNER | SYNCHRONIZE |
 				FILE_WRITE_DATA | FILE_APPEND_DATA |
 				FILE_WRITE_EA | FILE_WRITE_ATTRIBUTES |
 				FILE_DELETE_CHILD);
 
-	if (!inode_permission(user_ns, d_inode(dentry), MAY_OPEN | MAY_READ))
+	if (!inode_permission(idmap, d_inode(dentry), MAY_OPEN | MAY_READ))
 		*daccess |= FILE_READ_DATA_LE | FILE_READ_EA_LE;
 
-	if (!inode_permission(user_ns, d_inode(dentry), MAY_OPEN | MAY_EXEC))
+	if (!inode_permission(idmap, d_inode(dentry), MAY_OPEN | MAY_EXEC))
 		*daccess |= FILE_EXECUTE_LE;
 
 	parent = dget_parent(dentry);
-	ret = ksmbd_vfs_lock_parent(user_ns, parent, dentry);
+	ret = ksmbd_vfs_lock_parent(idmap, parent, dentry);
 	if (ret) {
 		dput(parent);
 		return ret;
 	}
 
-	if (!inode_permission(user_ns, d_inode(parent), MAY_EXEC | MAY_WRITE))
+	if (!inode_permission(idmap, d_inode(parent), MAY_EXEC | MAY_WRITE))
 		*daccess |= FILE_DELETE_LE;
 
 	inode_unlock(d_inode(parent));
@@ -200,7 +200,6 @@ int ksmbd_vfs_create(struct ksmbd_work *work, const char *name, umode_t mode)
 int ksmbd_vfs_mkdir(struct ksmbd_work *work, const char *name, umode_t mode)
 {
 	struct mnt_idmap *idmap;
-	struct user_namespace *user_ns;
 	struct path path;
 	struct dentry *dentry;
 	int err;
@@ -217,7 +216,6 @@ int ksmbd_vfs_mkdir(struct ksmbd_work *work, const char *name, umode_t mode)
 	}
 
 	idmap = mnt_idmap(path.mnt);
-	user_ns = mnt_idmap_owner(idmap);
 	mode |= S_IFDIR;
 	err = vfs_mkdir(idmap, d_inode(path.dentry), dentry, mode);
 	if (err) {
@@ -225,7 +223,7 @@ int ksmbd_vfs_mkdir(struct ksmbd_work *work, const char *name, umode_t mode)
 	} else if (d_unhashed(dentry)) {
 		struct dentry *d;
 
-		d = lookup_one(user_ns, dentry->d_name.name, dentry->d_parent,
+		d = lookup_one(idmap, dentry->d_name.name, dentry->d_parent,
 			       dentry->d_name.len);
 		if (IS_ERR(d)) {
 			err = PTR_ERR(d);
@@ -247,7 +245,7 @@ out:
 	return err;
 }
 
-static ssize_t ksmbd_vfs_getcasexattr(struct user_namespace *user_ns,
+static ssize_t ksmbd_vfs_getcasexattr(struct mnt_idmap *idmap,
 				      struct dentry *dentry, char *attr_name,
 				      int attr_name_len, char **attr_value)
 {
@@ -264,7 +262,7 @@ static ssize_t ksmbd_vfs_getcasexattr(struct user_namespace *user_ns,
 		if (strncasecmp(attr_name, name, attr_name_len))
 			continue;
 
-		value_len = ksmbd_vfs_getxattr(user_ns,
+		value_len = ksmbd_vfs_getxattr(idmap,
 					       dentry,
 					       name,
 					       attr_value);
@@ -287,7 +285,7 @@ static int ksmbd_vfs_stream_read(struct ksmbd_file *fp, char *buf, loff_t *pos,
 	ksmbd_debug(VFS, "read stream data pos : %llu, count : %zd\n",
 		    *pos, count);
 
-	v_len = ksmbd_vfs_getcasexattr(file_mnt_user_ns(fp->filp),
+	v_len = ksmbd_vfs_getcasexattr(file_mnt_idmap(fp->filp),
 				       fp->filp->f_path.dentry,
 				       fp->stream.name,
 				       fp->stream.size,
@@ -411,7 +409,7 @@ static int ksmbd_vfs_stream_write(struct ksmbd_file *fp, char *buf, loff_t *pos,
 				  size_t count)
 {
 	char *stream_buf = NULL, *wbuf;
-	struct user_namespace *user_ns = file_mnt_user_ns(fp->filp);
+	struct mnt_idmap *idmap = file_mnt_idmap(fp->filp);
 	size_t size, v_len;
 	int err = 0;
 
@@ -424,7 +422,7 @@ static int ksmbd_vfs_stream_write(struct ksmbd_file *fp, char *buf, loff_t *pos,
 		count = (*pos + count) - XATTR_SIZE_MAX;
 	}
 
-	v_len = ksmbd_vfs_getcasexattr(user_ns,
+	v_len = ksmbd_vfs_getcasexattr(idmap,
 				       fp->filp->f_path.dentry,
 				       fp->stream.name,
 				       fp->stream.size,
@@ -450,7 +448,7 @@ static int ksmbd_vfs_stream_write(struct ksmbd_file *fp, char *buf, loff_t *pos,
 
 	memcpy(&stream_buf[*pos], buf, count);
 
-	err = ksmbd_vfs_setxattr(user_ns,
+	err = ksmbd_vfs_setxattr(idmap,
 				 fp->filp->f_path.dentry,
 				 fp->stream.name,
 				 (void *)stream_buf,
@@ -586,7 +584,6 @@ int ksmbd_vfs_fsync(struct ksmbd_work *work, u64 fid, u64 p_id)
 int ksmbd_vfs_remove_file(struct ksmbd_work *work, char *name)
 {
 	struct mnt_idmap *idmap;
-	struct user_namespace *user_ns;
 	struct path path;
 	struct dentry *parent;
 	int err;
@@ -602,9 +599,8 @@ int ksmbd_vfs_remove_file(struct ksmbd_work *work, char *name)
 	}
 
 	idmap = mnt_idmap(path.mnt);
-	user_ns = mnt_idmap_owner(idmap);
 	parent = dget_parent(path.dentry);
-	err = ksmbd_vfs_lock_parent(user_ns, parent, path.dentry);
+	err = ksmbd_vfs_lock_parent(idmap, parent, path.dentry);
 	if (err) {
 		dput(parent);
 		path_put(&path);
@@ -744,7 +740,7 @@ static int __ksmbd_vfs_rename(struct ksmbd_work *work,
 	if (ksmbd_override_fsids(work))
 		return -ENOMEM;
 
-	dst_dent = lookup_one(mnt_idmap_owner(dst_idmap), dst_name,
+	dst_dent = lookup_one(dst_idmap, dst_name,
 			      dst_dent_parent, strlen(dst_name));
 	err = PTR_ERR(dst_dent);
 	if (IS_ERR(dst_dent)) {
@@ -777,7 +773,6 @@ int ksmbd_vfs_fp_rename(struct ksmbd_work *work, struct ksmbd_file *fp,
 			char *newname)
 {
 	struct mnt_idmap *idmap;
-	struct user_namespace *user_ns;
 	struct path dst_path;
 	struct dentry *src_dent_parent, *dst_dent_parent;
 	struct dentry *src_dent, *trap_dent, *src_child;
@@ -806,8 +801,7 @@ int ksmbd_vfs_fp_rename(struct ksmbd_work *work, struct ksmbd_file *fp,
 	dget(src_dent);
 	dget(dst_dent_parent);
 	idmap = file_mnt_idmap(fp->filp);
-	user_ns = mnt_idmap_owner(idmap);
-	src_child = lookup_one(user_ns, src_dent->d_name.name, src_dent_parent,
+	src_child = lookup_one(idmap, src_dent->d_name.name, src_dent_parent,
 			       src_dent->d_name.len);
 	if (IS_ERR(src_child)) {
 		err = PTR_ERR(src_child);
@@ -913,22 +907,22 @@ ssize_t ksmbd_vfs_listxattr(struct dentry *dentry, char **list)
 	return size;
 }
 
-static ssize_t ksmbd_vfs_xattr_len(struct user_namespace *user_ns,
+static ssize_t ksmbd_vfs_xattr_len(struct mnt_idmap *idmap,
 				   struct dentry *dentry, char *xattr_name)
 {
-	return vfs_getxattr(user_ns, dentry, xattr_name, NULL, 0);
+	return vfs_getxattr(idmap, dentry, xattr_name, NULL, 0);
 }
 
 /**
  * ksmbd_vfs_getxattr() - vfs helper for smb get extended attributes value
- * @user_ns:	user namespace
+ * @idmap:	idmap
  * @dentry:	dentry of file for getting xattrs
  * @xattr_name:	name of xattr name to query
  * @xattr_buf:	destination buffer xattr value
  *
  * Return:	read xattr value length on success, otherwise error
  */
-ssize_t ksmbd_vfs_getxattr(struct user_namespace *user_ns,
+ssize_t ksmbd_vfs_getxattr(struct mnt_idmap *idmap,
 			   struct dentry *dentry,
 			   char *xattr_name, char **xattr_buf)
 {
@@ -936,7 +930,7 @@ ssize_t ksmbd_vfs_getxattr(struct user_namespace *user_ns,
 	char *buf;
 
 	*xattr_buf = NULL;
-	xattr_len = ksmbd_vfs_xattr_len(user_ns, dentry, xattr_name);
+	xattr_len = ksmbd_vfs_xattr_len(idmap, dentry, xattr_name);
 	if (xattr_len < 0)
 		return xattr_len;
 
@@ -944,7 +938,7 @@ ssize_t ksmbd_vfs_getxattr(struct user_namespace *user_ns,
 	if (!buf)
 		return -ENOMEM;
 
-	xattr_len = vfs_getxattr(user_ns, dentry, xattr_name,
+	xattr_len = vfs_getxattr(idmap, dentry, xattr_name,
 				 (void *)buf, xattr_len);
 	if (xattr_len > 0)
 		*xattr_buf = buf;
@@ -955,7 +949,7 @@ ssize_t ksmbd_vfs_getxattr(struct user_namespace *user_ns,
 
 /**
  * ksmbd_vfs_setxattr() - vfs helper for smb set extended attributes value
- * @user_ns:	user namespace
+ * @idmap:	idmap of the relevant mount
  * @dentry:	dentry to set XATTR at
  * @name:	xattr name for setxattr
  * @value:	xattr value to set
@@ -964,13 +958,13 @@ ssize_t ksmbd_vfs_getxattr(struct user_namespace *user_ns,
  *
  * Return:	0 on success, otherwise error
  */
-int ksmbd_vfs_setxattr(struct user_namespace *user_ns,
+int ksmbd_vfs_setxattr(struct mnt_idmap *idmap,
 		       struct dentry *dentry, const char *attr_name,
 		       void *attr_value, size_t attr_size, int flags)
 {
 	int err;
 
-	err = vfs_setxattr(user_ns,
+	err = vfs_setxattr(idmap,
 			   dentry,
 			   attr_name,
 			   attr_value,
@@ -1080,19 +1074,18 @@ int ksmbd_vfs_fqar_lseek(struct ksmbd_file *fp, loff_t start, loff_t length,
 	return ret;
 }
 
-int ksmbd_vfs_remove_xattr(struct user_namespace *user_ns,
+int ksmbd_vfs_remove_xattr(struct mnt_idmap *idmap,
 			   struct dentry *dentry, char *attr_name)
 {
-	return vfs_removexattr(user_ns, dentry, attr_name);
+	return vfs_removexattr(idmap, dentry, attr_name);
 }
 
 int ksmbd_vfs_unlink(struct mnt_idmap *idmap,
 		     struct dentry *dir, struct dentry *dentry)
 {
 	int err = 0;
-	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 
-	err = ksmbd_vfs_lock_parent(mnt_userns, dir, dentry);
+	err = ksmbd_vfs_lock_parent(idmap, dir, dentry);
 	if (err)
 		return err;
 	dget(dentry);
@@ -1339,7 +1332,7 @@ out:
 	return err;
 }
 
-int ksmbd_vfs_remove_sd_xattrs(struct user_namespace *user_ns,
+int ksmbd_vfs_remove_sd_xattrs(struct mnt_idmap *idmap,
 			       struct dentry *dentry)
 {
 	char *name, *xattr_list = NULL;
@@ -1359,7 +1352,7 @@ int ksmbd_vfs_remove_sd_xattrs(struct user_namespace *user_ns,
 		ksmbd_debug(SMB, "%s, len %zd\n", name, strlen(name));
 
 		if (!strncmp(name, XATTR_NAME_SD, XATTR_NAME_SD_LEN)) {
-			err = ksmbd_vfs_remove_xattr(user_ns, dentry, name);
+			err = ksmbd_vfs_remove_xattr(idmap, dentry, name);
 			if (err)
 				ksmbd_debug(SMB, "remove xattr failed : %s\n", name);
 		}
@@ -1435,11 +1428,12 @@ out:
 }
 
 int ksmbd_vfs_set_sd_xattr(struct ksmbd_conn *conn,
-			   struct user_namespace *user_ns,
+			   struct mnt_idmap *idmap,
 			   struct dentry *dentry,
 			   struct smb_ntsd *pntsd, int len)
 {
 	int rc;
+	struct user_namespace *user_ns = mnt_idmap_owner(idmap);
 	struct ndr sd_ndr = {0}, acl_ndr = {0};
 	struct xattr_ntacl acl = {0};
 	struct xattr_smb_acl *smb_acl, *def_smb_acl = NULL;
@@ -1494,7 +1488,7 @@ int ksmbd_vfs_set_sd_xattr(struct ksmbd_conn *conn,
 		goto out;
 	}
 
-	rc = ksmbd_vfs_setxattr(user_ns, dentry,
+	rc = ksmbd_vfs_setxattr(idmap, dentry,
 				XATTR_NAME_SD, sd_ndr.data,
 				sd_ndr.offset, 0);
 	if (rc < 0)
@@ -1509,11 +1503,12 @@ out:
 }
 
 int ksmbd_vfs_get_sd_xattr(struct ksmbd_conn *conn,
-			   struct user_namespace *user_ns,
+			   struct mnt_idmap *idmap,
 			   struct dentry *dentry,
 			   struct smb_ntsd **pntsd)
 {
 	int rc;
+	struct user_namespace *user_ns = mnt_idmap_owner(idmap);
 	struct ndr n;
 	struct inode *inode = d_inode(dentry);
 	struct ndr acl_ndr = {0};
@@ -1521,7 +1516,7 @@ int ksmbd_vfs_get_sd_xattr(struct ksmbd_conn *conn,
 	struct xattr_smb_acl *smb_acl = NULL, *def_smb_acl = NULL;
 	__u8 cmp_hash[XATTR_SD_HASH_SIZE] = {0};
 
-	rc = ksmbd_vfs_getxattr(user_ns, dentry, XATTR_NAME_SD, &n.data);
+	rc = ksmbd_vfs_getxattr(idmap, dentry, XATTR_NAME_SD, &n.data);
 	if (rc <= 0)
 		return rc;
 
@@ -1583,7 +1578,7 @@ free_n_data:
 	return rc;
 }
 
-int ksmbd_vfs_set_dos_attrib_xattr(struct user_namespace *user_ns,
+int ksmbd_vfs_set_dos_attrib_xattr(struct mnt_idmap *idmap,
 				   struct dentry *dentry,
 				   struct xattr_dos_attrib *da)
 {
@@ -1594,7 +1589,7 @@ int ksmbd_vfs_set_dos_attrib_xattr(struct user_namespace *user_ns,
 	if (err)
 		return err;
 
-	err = ksmbd_vfs_setxattr(user_ns, dentry, XATTR_NAME_DOS_ATTRIBUTE,
+	err = ksmbd_vfs_setxattr(idmap, dentry, XATTR_NAME_DOS_ATTRIBUTE,
 				 (void *)n.data, n.offset, 0);
 	if (err)
 		ksmbd_debug(SMB, "failed to store dos attribute in xattr\n");
@@ -1603,14 +1598,14 @@ int ksmbd_vfs_set_dos_attrib_xattr(struct user_namespace *user_ns,
 	return err;
 }
 
-int ksmbd_vfs_get_dos_attrib_xattr(struct user_namespace *user_ns,
+int ksmbd_vfs_get_dos_attrib_xattr(struct mnt_idmap *idmap,
 				   struct dentry *dentry,
 				   struct xattr_dos_attrib *da)
 {
 	struct ndr n;
 	int err;
 
-	err = ksmbd_vfs_getxattr(user_ns, dentry, XATTR_NAME_DOS_ATTRIBUTE,
+	err = ksmbd_vfs_getxattr(idmap, dentry, XATTR_NAME_DOS_ATTRIBUTE,
 				 (char **)&n.data);
 	if (err > 0) {
 		n.length = err;
@@ -1682,7 +1677,7 @@ int ksmbd_vfs_fill_dentry_attrs(struct ksmbd_work *work,
 				   KSMBD_SHARE_FLAG_STORE_DOS_ATTRS)) {
 		struct xattr_dos_attrib da;
 
-		rc = ksmbd_vfs_get_dos_attrib_xattr(mnt_idmap_owner(idmap), dentry, &da);
+		rc = ksmbd_vfs_get_dos_attrib_xattr(idmap, dentry, &da);
 		if (rc > 0) {
 			ksmbd_kstat->file_attributes = cpu_to_le32(da.attr);
 			ksmbd_kstat->create_time = da.create_time;
@@ -1694,7 +1689,7 @@ int ksmbd_vfs_fill_dentry_attrs(struct ksmbd_work *work,
 	return 0;
 }
 
-ssize_t ksmbd_vfs_casexattr_len(struct user_namespace *user_ns,
+ssize_t ksmbd_vfs_casexattr_len(struct mnt_idmap *idmap,
 				struct dentry *dentry, char *attr_name,
 				int attr_name_len)
 {
@@ -1711,7 +1706,7 @@ ssize_t ksmbd_vfs_casexattr_len(struct user_namespace *user_ns,
 		if (strncasecmp(attr_name, name, attr_name_len))
 			continue;
 
-		value_len = ksmbd_vfs_xattr_len(user_ns, dentry, name);
+		value_len = ksmbd_vfs_xattr_len(idmap, dentry, name);
 		break;
 	}