fs: port ->setattr() 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>

4 files changed, 9 insertions, 10 deletions

diff --git a/include/linux/evm.h b/include/linux/evm.h
index 7a9ee2157f69..1f8f806dd0d1 100644
--- a/include/linux/evm.h
+++ b/include/linux/evm.h
@@ -21,7 +21,7 @@ extern enum integrity_status evm_verifyxattr(struct dentry *dentry,
 					     void *xattr_value,
 					     size_t xattr_value_len,
 					     struct integrity_iint_cache *iint);
-extern int evm_inode_setattr(struct user_namespace *mnt_userns,
+extern int evm_inode_setattr(struct mnt_idmap *idmap,
 			     struct dentry *dentry, struct iattr *attr);
 extern void evm_inode_post_setattr(struct dentry *dentry, int ia_valid);
 extern int evm_inode_setxattr(struct user_namespace *mnt_userns,
@@ -90,7 +90,7 @@ static inline enum integrity_status evm_verifyxattr(struct dentry *dentry,
 }
 #endif
 
-static inline int evm_inode_setattr(struct user_namespace *mnt_userns,
+static inline int evm_inode_setattr(struct mnt_idmap *idmap,
 				    struct dentry *dentry, struct iattr *attr)
 {
 	return 0;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 7aa302d2ce39..24e378e2835f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2152,8 +2152,7 @@ struct inode_operations {
 		      umode_t,dev_t);
 	int (*rename) (struct user_namespace *, struct inode *, struct dentry *,
 			struct inode *, struct dentry *, unsigned int);
-	int (*setattr) (struct user_namespace *, struct dentry *,
-			struct iattr *);
+	int (*setattr) (struct mnt_idmap *, struct dentry *, struct iattr *);
 	int (*getattr) (struct user_namespace *, const struct path *,
 			struct kstat *, u32, unsigned int);
 	ssize_t (*listxattr) (struct dentry *, char *, size_t);
@@ -3313,7 +3312,7 @@ extern int dcache_dir_open(struct inode *, struct file *);
 extern int dcache_dir_close(struct inode *, struct file *);
 extern loff_t dcache_dir_lseek(struct file *, loff_t, int);
 extern int dcache_readdir(struct file *, struct dir_context *);
-extern int simple_setattr(struct user_namespace *, struct dentry *,
+extern int simple_setattr(struct mnt_idmap *, struct dentry *,
 			  struct iattr *);
 extern int simple_getattr(struct user_namespace *, const struct path *,
 			  struct kstat *, u32, unsigned int);
@@ -3368,9 +3367,9 @@ extern void generic_set_encrypted_ci_d_ops(struct dentry *dentry);
 
 int may_setattr(struct user_namespace *mnt_userns, struct inode *inode,
 		unsigned int ia_valid);
-int setattr_prepare(struct user_namespace *, struct dentry *, struct iattr *);
+int setattr_prepare(struct mnt_idmap *, struct dentry *, struct iattr *);
 extern int inode_newsize_ok(const struct inode *, loff_t offset);
-void setattr_copy(struct user_namespace *, struct inode *inode,
+void setattr_copy(struct mnt_idmap *, struct inode *inode,
 		  const struct iattr *attr);
 
 extern int file_update_time(struct file *file);
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index d92fdfd2444c..7c9628dc61a3 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -405,7 +405,7 @@ extern int nfs_clear_invalid_mapping(struct address_space *mapping);
 extern bool nfs_mapping_need_revalidate_inode(struct inode *inode);
 extern int nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping);
 extern int nfs_revalidate_mapping_rcu(struct inode *inode);
-extern int nfs_setattr(struct user_namespace *, struct dentry *, struct iattr *);
+extern int nfs_setattr(struct mnt_idmap *, struct dentry *, struct iattr *);
 extern void nfs_setattr_update_inode(struct inode *inode, struct iattr *attr, struct nfs_fattr *);
 extern void nfs_setsecurity(struct inode *inode, struct nfs_fattr *fattr);
 extern struct nfs_open_context *get_nfs_open_context(struct nfs_open_context *ctx);
diff --git a/include/linux/security.h b/include/linux/security.h
index 5b67f208f7de..1ba1f4e70b50 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -356,7 +356,7 @@ int security_inode_readlink(struct dentry *dentry);
 int security_inode_follow_link(struct dentry *dentry, struct inode *inode,
 			       bool rcu);
 int security_inode_permission(struct inode *inode, int mask);
-int security_inode_setattr(struct user_namespace *mnt_userns,
+int security_inode_setattr(struct mnt_idmap *idmap,
 			   struct dentry *dentry, struct iattr *attr);
 int security_inode_getattr(const struct path *path);
 int security_inode_setxattr(struct user_namespace *mnt_userns,
@@ -862,7 +862,7 @@ static inline int security_inode_permission(struct inode *inode, int mask)
 	return 0;
 }
 
-static inline int security_inode_setattr(struct user_namespace *mnt_userns,
+static inline int security_inode_setattr(struct mnt_idmap *idmap,
 					 struct dentry *dentry,
 					 struct iattr *attr)
 {